US20080190775A1 - Method of electrodeposition coating on a hub - Google Patents
Method of electrodeposition coating on a hub Download PDFInfo
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- US20080190775A1 US20080190775A1 US11/765,549 US76554907A US2008190775A1 US 20080190775 A1 US20080190775 A1 US 20080190775A1 US 76554907 A US76554907 A US 76554907A US 2008190775 A1 US2008190775 A1 US 2008190775A1
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- United States
- Prior art keywords
- coating
- hub
- section
- cylindrical section
- coating liquid
- Prior art date
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
- B60B27/00—Hubs
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D13/00—Electrophoretic coating characterised by the process
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D13/00—Electrophoretic coating characterised by the process
- C25D13/12—Electrophoretic coating characterised by the process characterised by the article coated
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D13/00—Electrophoretic coating characterised by the process
- C25D13/12—Electrophoretic coating characterised by the process characterised by the article coated
- C25D13/14—Tubes; Rings; Hollow bodies
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C19/00—Bearings with rolling contact, for exclusively rotary movement
- F16C19/02—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
- F16C19/14—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load
- F16C19/18—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/30—Parts of ball or roller bearings
- F16C33/58—Raceways; Race rings
- F16C33/64—Special methods of manufacture
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Rolling Contact Bearings (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
Abstract
A method is realized for easily performing, without using a masking tape, an operation to accurately form a coating film 31 only on a coated section (α8) partly formed on the surface of a hub main body 13 a.
The upper end face of a rubber closed end cylindrical masking cover 32 is elastically pressed against the outside end surface of a cylindrical section 16 forming the hub main body 13 a. As a result a border section between the coated section (α8) and the portion adjacent to the coated section (α8) can be made liquid-tight. In this state, coating particles are electrodeposited on the coated section (α8) by bringing a coating liquid 28 discharged from a liquid supply tube 29 into contact with the coated section (α8). By adopting such a method, the problems can be solved.
Description
- A method of electrodeposition coating on a hub according to the present invention is used for forming an antirust coating film on a surface of a cylindrical section provided on an outside end section of a hub that constitutes a wheel support hub unit.
- A
wheel 1 that constitutes a vehicle wheel and arotor 2 that constitutes a disk brake, which is a braking rotating member serving as a braking device, are rotatably supported on a knuckle 3 that constitutes a suspension device, by a structure shown inFIG. 25 for example. That is, anouter ring 6 that constitutes a wheelsupport hub unit 5 is fixed by a plurality of bolts 7 to a circular shaped support hole 4 formed in this knuckle 3. Meanwhile, thewheel 1 and therotor 2 are joined and fixed by a plurality of studs 9 and nuts 10 onto ahub 8 that constitutes this wheelsupport hub unit 5. - A double-row of
outer ring raceways outer ring 6, and ajoint flange 12 is formed on an outer peripheral surface. Such anouter ring 6 is fixed on the knuckle 3 by fixing thejoint flange 12 by the respective bolts 7 onto the knuckle 3. - Meanwhile, the
hub 8 is constructed with a hubmain body 13 and aninner ring 14. Anattachment flange 15 is formed on a part projecting from an outside end opening of theouter ring 6 on one part of the outer peripheral surface of the hubmain body 13. (“Outside” in an axial direction refers to downside in each diagram except forFIG. 5 ,FIG. 25 andFIG. 26 and left side inFIG. 25 andFIG. 26 , which is the outside in a width direction of a vehicle when assembled in an automobile. On the other hand, “inside” in the axial direction refers to the upper side in each diagram except forFIG. 5 ,FIG. 25 andFIG. 26 and right side inFIG. 25 andFIG. 26 , which is the center side in the width direction of the vehicle when assembled in an automobile. This applies to the entire present specification and the entire claims.) Moreover, acylindrical section 16 called a pilot section is provided on the outer end section of the hubmain body 13 so as to be concentric with the hubmain body 13. Thewheel 1 and therotor 2, having been positioned in a radial direction by being fitted onto thiscylindrical section 16, are joined and fixed by the respective studs 9 and nuts 10 onto an outside surface of theattachment flange 15. - Moreover, an
inner ring raceway 17 a opposing to theouter ring raceway 11 a on the outside of the double-row ofouter ring raceways main body 13, and a smalldiameter step section 18 is formed on the inner end section of the same. Theinner ring 14 is fitted onto this smalldiameter step section 18. Aninner ring raceway 17 b opposing to theouter ring raceway 11 b on the inside of the double-row of theouter ring raceways inner ring 14. Such aninner ring 14 is fixed onto this hubmain body 13 by a crimpedsection 19 formed by plastically deforming the inside end section of the hubmain body 13 outward in the radial direction. A plurality ofrolling bodies 20 are respectively rollably provided between the respectiveouter ring raceways inner ring raceways inner ring raceway 17 a on the outside is directly formed on the middle section of the outer peripheral surface of the hubmain body 13, however, thisinner ring raceway 17 a on the outside may be formed on the outer peripheral surface of a separateinner ring 14 a that is fitted onto the middle section of the hubmain body 13 as shown inFIG. 25 with a double-dashed chain line (imaginary line). Moreover, in the example shown in the diagram, a ball is used as each of therolling bodies 20, however, a tapered roller may be used in the case of a hub unit for a heavy automobile. Furthermore, opening sections of both ends of a cylindrical shaped space in which the respectiverolling bodies 20 have been installed are respectively sealed byseal rings - Furthermore, in the example shown in the diagram, since it is a wheel
support hub unit 5 for a driving wheel (front wheels of FF vehicle, rear wheels of FR/RR vehicle, or all wheels of 4WD vehicle), aspline hole 22 is formed in a center section of thehub 8. Aspline shaft 24 fixed on an outside end surface of a constant velocity jointouter ring 23 is inserted in thisspline hole 22. Along with this, by screwing anut 25 onto a tip end section of thisspline shaft 24 and further tightening it, the hubmain body 13 is tightly held between thisnut 25 and the constant velocity jointouter ring 23. - Next,
FIG. 26 shows a second example of a conventionally known wheel support hub unit for a driven wheel (rear wheels of a FF vehicle and front wheels of a FR/RR vehicle). Since a wheelsupport hub unit 5 a of this second example is for a driven wheel, the spline hole is not provided in the center section of the hubmain body 13 a that constitutes ahub 8 a. Also in the case of the present example, theinner ring raceway 17 a on the outside is directly formed in the middle section of the outer peripheral surface of the hubmain body 13 a, however, theinner ring raceway 17 a on the outside may be formed on an outer peripheral surface of a separate inner ring (not shown in the diagram) that is fitted onto the middle section of the hubmain body 13 a. Moreover, in the example shown in the diagram, the inside end surface of theinner ring 14 is held by the crimpedsection 19 provided on the inside end section of the hubmain body 13 a, however, the inside end surface of theinner ring 14 may be held by a nut screwed onto the inside end surface of the hubmain body 13 a. In this case, a male screw section is provided on the inside end section of the hubmain body 13 a for screwing the nut. Other constructions and effects of the other parts are similar to those of the first example described above. - Incidentally, in the case of the wheel
support hub units cylindrical section 16 in the hubmain bodies FIG. 27 for example, depending on the purpose of the coating film. Moreover, as a method of forming a coating film on the surface to be coated, various methods such as a brush coating method or an electrodeposition coating method are conventionally known (for example, refer toPatent Documents -
FIG. 28 shows an example of the electrodeposition coating method disclosed inPatent Document 2. In the case of the present example, the surface to be coated is a part shown with the broken line α1 inFIG. 28 andFIG. 27 (A), that is, an outer peripheral surface of an outside half part, an inner peripheral surface of the outside half part, and an outside end surface, of thecylindrical section 16 that constitutes the hubmain body 13. When forming a coating film on such a surface to be coated (α1), first, preprocessing such as degreasing cleaning is carried out on this surface to be coated (α1). Next, as shown inFIG. 28 , with an electrode 30 a fixed on a top surface of a supportingbase 26 brought into contact with the hubmain body 13 and an outside surface of theattachment flange 15 that constitutes this hubmain body 13 supported on a supporting base not shown in the diagram, the outside half part of thecylindrical section 16 is dipped in acoating liquid 28 filled in acoating liquid tank 27. Thus, thiscoating liquid 28 is brought into contact with the entire surface to be coated (α1). The operation of dipping at this time is carried out by continuously supplying the coatingliquid 28 into the coatingliquid tank 27 through aliquid supply pipe 29 while overflowing thiscoating liquid 28 from a top end edge of this coatingliquid tank 27. The reason for carrying out the dipping operation in this way is to maintain the position of the liquid surface of thecoating liquid 28 and to appropriately regulate a coating range of thecylindrical section 16. - Once the
coating liquid 28 has come into contact with the entire surface to be coated (α1) as described above, subsequently, in this state, a voltage is applied between anelectrode 30 b installed in thecoating liquid 28 and the electrode 30 a in contact with the hub main body 13 (for example, respectively, theelectrode side 30 b is connected to a positive pole and the electrode 30 a side is connected to a negative pole). As a result, anundried coating film 31 is formed on the surface to be coated (α1) by ionizing the coating particles in the coatingliquid 28 and electrodepositing these ionized coating particles on the surface to be coated (α1). Next, thecylindrical section 16 is taken out from thecoating liquid 28, this undriedcoating film 31 is heated to dry it, and thereby thiscoating film 31 is baked onto the surface to be coated (α1). Lastly, thiscoating film 31 is cooled and coating operation is complete. In the example shown in the diagram, thiscoating film 31 is shown with a heavy line for the sake of simplicity, however, the width of this heavy line does not represent the thickness of thiscoating film 31. The actual thickness of thecoating film 31 is, for example, approximately several μm once it has been subjected to baking, depending on the length of time for which the above mentioned electric voltage has been applied. This point is the same as that in another conventional method described later and as that in the embodiments of the present invention. - As described above, in the case of the conventional electrodeposition coating method shown in
FIG. 28 , as a method of bringing the surface to be coated into contact with thecoating liquid 28, a method of simply dipping a part of the hubmain body 13 in thecoating liquid 28 filled in the coatingliquid tank 27 is employed. In such a conventional electrodeposition coating method, in the case where the entire surface of the dipped part becomes a surface to be coated when a part of the hubmain body 13 is dipped in the coating liquid 28 (for example, in the case of forming thecoating film 31 on this surface to be coated up to a same position in the axial direction on both the inner and outer peripheral surfaces of thecylindrical section 16 as shown inFIG. 27 (A) andFIG. 28 with broken line α1), there will be no particular problem. However, in the case where only one part of the surface of the dipped part becomes the surface to be coated (for example, when the positions of the end sections of thecoating film 31 of this surface to be coated on both the inner and outer peripheral surfaces of thecylindrical section 16 differ from each other in an axial direction as shown inFIG. 27 (B) to (H) with broken lines α2 to α8), the coating range cannot be appropriately regulated as parts other than this surface to be coated also come into contact with thecoating liquid 28. In this case, only the surface to be coated can be brought into contact with thecoating liquid 28 if dipping is carried out with a masking tape attached to the parts other than the surface to be coated, however, since there is a need for carrying out operations of attaching and removing the masking tape before and after the dipping operation, the coating operation becomes troublesome. - Furthermore, in the case where the coating film is formed by means of electrodeposition coating on the outside end portion to middle portion of the outer peripheral surface, the outside end surface, and the inner peripheral surface of the
cylindrical section 16 and on the part of the outside end surface of the hubmain body 13, the circumference of which is surrounded by the cylindrical section 16 (the part shown with the broken line α6), first, preprocessing such as degreasing cleaning is carried out on the part shown with the broken line α6. - Next, the operation of electrodepositing coating particles on the part shown with the broken line α6 (the operation of forming an undried coating film 54) is carried out using a
coating device 46 such as is shown inFIG. 30 for example. Thecoating device 46 is provided with: a coatingliquid tank 48 that is filled with acoating liquid 47 and has an opening on the top end thereof; arecovery tank 49 that is provided around this coatingliquid tank 48 to collect thecoating liquid 47 that is overflowed from the top end edge of this coatingliquid tank 48; and anozzle 52 that is provided in a vertical direction passing through center sections of respectivebottom plate sections liquid tank 48 and therecovery tank 49 so as to be air-tight and liquid-tight, and that injects thecoating liquid 47 from the top end opening thereof by action of a pump not shown in the diagram. On the top end section of thisnozzle 52, aguide section 53 is provided with a shape in which this entire top end section has been bent back outward in the radial direction into a U-shape. Moreover, the top end edge of thisnozzle 52 is arranged above the surface of thecoating liquid 47 filled in the coatingliquid tank 48. - In the case where the coating particles are electrodeposited on the part shown with die broken line α6 using such a
coating device 46, as shown in the diagram, the outside end portion to middle portion of thecylindrical section 16 is dipped in thecoating liquid 47 filled in the coatingliquid tank 48. Meanwhile, an outer surface of theguide section 53 provided on the top end section of thenozzle 52 is made to oppose across its entirety the part of the outside end surface of the hubmain body 13 a, the circumference of which is surrounded by thecylindrical section 16, and the inner peripheral surface of thiscylindrical section 16. In this state, by ejectingcoating liquid 47 upwards from the top end opening of thenozzle 52, this ejectedcoating liquid 47 is made to flow through a gap part between the above-mentioned surfaces opposing to each other, in a state where this gap part is entirely filled with thecoating liquid 47. Thus, Hiscoating liquid 47 is brought into contact respectively with the entire part of the outside end surface of the hubmain body 13 a, the circumference of which is surrounded by thecylindrical section 16, and with the entire inner peripheral surface of thecylindrical section 16. Thus, the entire part shown with the broken line α6 is brought into contact with thecoating liquid 47. - Moreover, the
coating liquid 47 ejected from the top end opening of thenozzle 52 as described above is poured into the interior of the coatingliquid tank 48. Then the coatingliquid 47 filled in thecoating liquid tank 48 overflows by the amount that has been poured in this way to the exterior from the top end edge of thecoating liquid tank 48. Thecoating liquid 47 overflowed like this is recovered by therecovery tank 49, and it is re-used as thecoating liquid 47 to be ejected from the top end opening of thenozzle 52. - Once the entire part shown with the broken line α6 has been brought into contact with the
coating liquid 47 as described above, subsequently, in this state, an electric voltage is applied between an electrode, not shown in the diagram, in contact with another part of thiscoating liquid 47 and the hubmain body 13 a (for example, the electrode side is connected to a positive pole and the hub main body side is connected to a negative pole). As a result, by ionizing the coating particles in thecoating liquid 47 and electrodepositing these ionized coating particles on the part shown with the broken line α6, anundried coating film 54 is formed on this part. Once theundried coating film 54 has been formed as described above, thereafter, thiscoating film 54 is baked onto the abovementioned surface by heating thisundried coating film 54 to dry it, and then thiscoating film 54 is cooled down to complete the coating operation. - In the case where the operation of electrodepositing the coating particles on the part shown with the broken line α6 is carried out as described above within one step, undulations occur on the part of the surface of the
coating liquid 47 filled in thiscoating liquid tank 48 in the radial direction outer side of thecylindrical section 16, depending on a liquid flow of thecoating liquid 47 when it is ejected from the top end opening of thenozzle 52 and poured into thecoating liquid tank 48. As a result, a range of thecoating liquid 47 that comes in contact with the outer peripheral surface of thecylindrical section 16 changes in response to the movement of the above undulations, the shape of the edge of thecoating film 54 to be formed on the outer peripheral surface of thiscylindrical section 16 does not become a straight line when seen from the radial direction outer side of thecylindrical section 16 and becomes corrugated, and thecoating film 54 may not be accurately formed on a part on which thecoating film 54 is to be formed. - Moreover, in the case of forming a coating film on the surface of the
cylindrical section 16 that constitutes the hubmain bodies main bodies cylindrical section 16 is in contact with the coating liquid. Thus, an undried coating film is formed on the surface of thecylindrical section 16 by ionizing the coating particles in the coating liquid and electrodepositing these ionized coating particles onto this surface. Subsequently, this undried coating film is heated to dry it, thereby baking this coating film onto the above surface, and then this coating film is cooled to complete the coating operation. - Incidentally, when baking the coating film onto the surface of the
cylindrical section 16 as described above, inappropriate heating of the undried coating film gives rise to the following problems. Specifically, a hardened layer is formed on at least one part of the middle section to the section close to the inside end of the outer peripheral surface of the hubmain bodies attachment flange 15, a part on which theinner ring raceway 17 a has been formed, and a part with which theinner rings support hub units bodies 20 rises excessively as a result of inappropriate heating of this undried coating film, a problem of this grease degrading occurs. - Patent Document 1: Japanese Patent Application Publication No. 2003-136902
- Patent Document 2: Japanese Patent Application Publication No. 2003-342793
- In consideration of the above described problems, a method of electrodeposition coating on a hub according to a first aspect of the present invention has been invented to realize an easy operation of forming a coating film only in a desired range on a surface of a hub without using masking tape.
- Moreover, in consideration of the above described problems, a method of electrodeposition coating on a hub according to a second aspect of the present invention has been invented to realize a method that enables accurate formation of a coating film in a desired range including at least a surface of a cylindrical section among the surfaces of the hub.
- Moreover, in consideration of the above described problems, a method of electrodeposition coating on a hub according to third and fourth aspects of the present invention has been invented to realize a method that can prevent an excessive increase in temperature of a part on an outer peripheral surface of the hub on which a hardened layer has been formed by means of high frequency hardening processing, or that can prevent an excessive increase in the temperature of grease enclosed in a rolling body installation section, in the case of applying heat to an undried coating film to bake the coating film onto the surface of the cylindrical section that constitutes the hub.
- In a method of electrodeposition coating on a hub according to a first aspect of the present invention, in order to form a coating film on a desired range that includes at least one part of a surface of a cylindrical section among the surfaces of a hub that constitutes a wheel support hub unit that is respectively provided with an attachment flange on a part close to an outside end of an outer peripheral surface for supporting and fixing a wheel and a braking rotating member, and with the cylindrical section for externally engaging at least one of the wheel and the braking rotating member on an outside end section, coating particles in a coating liquid are electrodeposited on this desired range, with the desired range in contact with the coating liquid.
- In particular, in the method of electrodeposition coating on a hub according to the first aspect of the present invention, the operation of electrodepositing the coating particles on the desired range is carried out with a masking cover in contact with or closely opposing to a border part on the surface of the hub between the desired range and a range adjacent to this desired range.
- An opposing clearance in the case of having the masking cover closely opposed to the border part is to be made as small as machine adjustment allows (preferably no greater than 1 mm (more preferably no greater than 0.5 mm)) so that even in the case where the coating liquid leaks from a gap created in this opposing section, a leak amount becomes minute.
- Moreover, the method of electrodeposition coating on a hub according to the first aspect of the present invention may be carried out for a hub (single hub body) prior to assembly of the wheel support hub unit, and it may also be carried out for a hub in a condition where this wheel support hub unit has been assembled.
- In a method of electrodeposition coating on a hub according to a second aspect of the present invention, in order to form a coating film on a desired range that includes at least a surface of a cylindrical section among the surfaces of a hub that constitutes a wheel support hub unit that is respectively provided with an attachment flange on a part close to an outside end of an outer peripheral surface for supporting and fixing a wheel and a braking rotating member, and with the cylindrical section for externally engaging at least one of the wheel and the braking rotating member on an outside end section, coating particles in a coating liquid are electrodeposited on this desired range, with the desired range in contact with the coating liquid.
- In particular, in the method of electrodeposition coating on a hub according to the second aspect of the present invention, a plurality of partial ranges that respectively become a range of one part of the desired range are set, and the operation of electrodepositing the coating particles on the desired range is carried out in separate processes for each of the partial ranges.
- Furthermore, in the case of setting the plurality of partial ranges, as long as all of the partial ranges together cover the above entire desired range, overlaps between the respective partial ranges do not cause a problem.
- Moreover, the method of electrodeposition coating on a hub according to the second aspect of the present invention may be carried out for a single hub body prior to assembly of the wheel support hub unit, and it may be carried out for a hub in a condition where this wheel support hub unit has been assembled.
- In a method of electrodeposition coating on a hub according to third and fourth aspects of the present invention, after forming an undried coating film on a surface of a cylindrical section among the surfaces of a hub that constitutes a wheel support hub unit respectively provided with an attachment flange on a part close to an outside end of an outer peripheral surface for supporting and fixing a wheel and a braking rotating member, and with the cylindrical section for externally engaging at least one of the wheel and the braking rotating member on an outside end section, by electrodeposition (ionized) coating particles onto the surface, the coating film is baked onto the surface of the cylindrical section by heating the undried coating film to dry it.
- In particular, in the method of electrodeposition coating on a hub according to the third aspect of the present invention, the heating temperature of the undried coating film is below 140° C.
- Moreover, in the method of electrodeposition coating on a hub according to the fourth aspect of the present invention, the heating temperature of the undried coating film is between 140° C. and 220° C., and the operation of heating the undried coating film is carried out while the hub is being cooled from an inside end side (the part of this hub on the inside end side of the cylindrical section).
- Moreover, the method of electrodeposition coating on a hub according to the third and fourth aspects of the present invention may be carried out for a single hub body prior to assembly of the wheel support hub unit, and it may be carried out for a hub in a condition where this wheel support hub unit has been assembled.
- As described above, in the case of the method of electrodeposition coating on a hub according to the first aspect of the present invention, the operation of electrodepositing coating particles onto a desired range is carried out with a masking cover in contact with or closely opposed to a border part between the desired ranged of the surface of the hub and the range adjacent to this desired range (with these both ranges separated from each other). Therefore, during this operation, coating liquid that has been brought into contact with this desired range can be prevented from coming into contact with the range adjacent to this desired range. In particular, in the case of the present invention, the above described prevention effect can be achieved without attaching masking tape to this adjacent range, by only placing the masking cover in contact with, or in a condition closely opposing to, the border part. Therefore, according to the present invention, the operation of forming a coating film only on the desired range can be carried out easily.
- As described above, in the case of the method of electrodeposition coating on a hub according to the second aspect of the present invention, since the operation of electrodepositing the coating particles on the desired range of the surface of the hub is carried out in separate processes for each of a plurality of partial ranges, coating of each of the partial ranges can be accurately carried out. Therefore, coating of the entire desired range can be accurately carried out.
- Furthermore, according to the method of electrodeposition coating on a hub according to the third and fourth aspects of the present invention described above, when heating the undried coating film to bake the coating film onto the surface of the cylindrical section, the temperature of a hardened layer, which is a part on the outer peripheral surface of the hub upon which high frequency hardening processing has been carried out, does not rise excessively (the temperature does not rise to a temperature at which a softening effect such as annealing or tempering starts to occur in this hardened layer), and an excessive increase in the temperature of grease enclosed in a rolling body installation section that constitutes the wheel support hub unit (the temperature does not rise to a temperature at which this grease degrades) can be prevented.
- Specifically, in the case of the wheel support hub unit shown in
FIG. 25 andFIG. 26 mentioned above, the tempering temperature in the case of forming the hardened layer with furnace heating is between 150° C. and 180° C. Therefore, depending on a length of time for which the hardened layer is to be exposed to the temperature, as long as the temperature is maintained below 150° C., a softening effect such as tempering does not occur in the hardened layer within the length of time required for drying of the undried coating film. For example, even if the hardened layer has been exposed for 30 minutes at 140° C., a softening effect such as tempering does not occur in the hardened layer. Furthermore, in the case of the wheel support hub unit shown inFIG. 25 andFIG. 26 mentioned above, if the temperature of the grease enclosed in the rolling body installation section reaches dropping point (this varies depending on the type of grease, but an example would be about 260° C.), the grease degrades regardless of exposure time, however, up to approximately 120° C. the grease does not degrade regardless of exposure time, and at approximately 140° C. it does not degrade within a length of time required for drying the coating film (for example, no more than 30 minutes). - On the other hand, as described above, in the case of the method of electrodeposition coating on a hub according to the third aspect of the present invention, the heating temperature of the coating film is low and no greater than 140° C. Therefore, even in the case where the heat applied to this coating film is transmitted to the above hardened layer, the temperature of this hardened layer does not rise excessively. Moreover, even if this heat is transmitted to the grease, the temperature of this grease does not rise to the temperature at which degradation starts to occur.
- Furthermore, as described above, in the case of the method of electrodeposition coating on a hub according to the fourth aspect of the present invention, the heating temperature of the undried coating film is raised comparatively high, within a range 140° C. to 220° C., however, the operation of heating the undried coating film is carried out while the hub is being cooled from the inside end side. As a result, an increase in the temperature of the hardened layer and in the grease due to the heat applied to the coating film can be suppressed. Therefore, softening in the hardened layer due to an excessive temperature increase, or degradation in the grease due to an excessive temperature increase can be prevented. Furthermore, in the case of the method of electrodeposition coating on a hub according to the fourth aspect of the present invention, since the heating temperature of the undried coating film is raise comparatively high, a length of time required for baking this coating film can be shortened.
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FIG. 1 is a sectional view that shows a first embodiment of the present invention in a state where a surface to be coated is brought into contact with coating liquid. -
FIG. 2 is a sectional view that shows a state after the state inFIG. 1 where the coating liquid is drained from interior of a masking cover and air is blown into an outside end opening of a cylindrical section. -
FIG. 3 is a sectional view showing a second embodiment of the present invention. -
FIG. 4 is a sectional view showing a third embodiment of the present invention. -
FIG. 5 is a top view of the masking cover seen from above inFIG. 3 . -
FIG. 6 is a sectional view for explaining a problem that occurs in the case where liquid drain passages such as cutouts on a top end edge portion of the masking cover are not provided. -
FIG. 7 is a sectional view showing a fourth embodiment of the present invention. -
FIG. 8 is a sectional view showing a fifth embodiment of the present invention. -
FIG. 9 is a sectional view showing a sixth embodiment of the present invention. -
FIG. 10 is a sectional view showing a seventh embodiment of the present invention. -
FIG. 11 is a sectional view that shows an eighth embodiment in a state where a first process operation of electrodeposition coating is being carried out. -
FIG. 12 is a sectional view that shows the same embodiment in a state where a second process operation of electrodeposition coating is being carried out. -
FIG. 13 is a sectional view that shows a ninth embodiment of the present invention in a state where a first process operation of electrodeposition coating is being carried out. -
FIG. 14 is a sectional view that shows the same embodiment in a state Where a second process operation of electrodeposition coating is being carried out. -
FIG. 15 is a sectional view that shows a tenth embodiment of the present invention in a state where a first process operation of electrodeposition coating is being carried out. -
FIG. 16 is a sectional view that shows the same embodiment in a state where a second process operation of electrodeposition coating is being carried out. -
FIG. 17 is a sectional view that shows an eleventh embodiment of the present invention in a state where a first process operation of electrodeposition coating is being carried out. -
FIG. 18 is a sectional view that shows the same embodiment in a state where a second process operation of electrodeposition coating is being carried out. -
FIG. 19 is a sectional view of a hub main body to which electrodeposition coating is to be applied, showing a twelfth embodiment of the present invention. -
FIG. 20 is a sectional view of the hub main body shown in a state where an undried coating film has been formed on a surface of the cylindrical section. -
FIG. 21 is a sectional view of the hub main body that shows a process of baking this coating film on the surface of the cylindrical section by heating the undried coating film. -
FIG. 22 is a sectional view of the hub main body that shows a process of cooling the coating film that has been baked on the surface of the cylindrical section. -
FIG. 23 is a sectional view of the hub main body that shows a process of baking a coating film on the surface of the cylindrical section by heating this undried coating film in a thirteenth embodiment of the present invention. -
FIG. 24 is a sectional view of the hub main body that shows a process of cooling the coating film that has been baked on the surface of the cylindrical section. -
FIG. 25 is a sectional view that shows one example of a wheel support hub unit for a driving wheel in a state of being assembled to a knuckle. -
FIG. 26 is a sectional view that shows an example of the wheel support hub unit for a driven wheel. -
FIG. 27 is a diagram showing eight examples of ranges in which the coating film is to be formed. -
FIG. 28 is a sectional view that shows a first example of a conventional electrodeposition coating method. -
FIG. 29 is a sectional view of the hub main body that constitutes the wheel support hub unit for the driven wheel shown inFIG. 26 . -
FIG. 30 is a sectional view that shows a second example of a conventional electrodeposition coating method. - A method of electrodeposition coating on a hub according to a first aspect of the present invention can be carried out where a border section, which is to come into contact with, or closely oppose, the masking cover, is a periphery part (outer periphery part or inner periphery part) of an outside end surface of a cylindrical section that constitutes the hub.
- Moreover, in the case where a hole that passes through this hub in an axial direction is provided in a center section of the hub, the above-mentioned method can be carried out where a border section, which is to come into contact with, or closely oppose, the masking cover, is an annular section that surrounds an outside end opening of the above hole of the outside end surface of the hub which is surrounded by the cylindrical section.
- Furthermore, when carrying out these embodiments of the present invention after coating particles in a coating liquid have been electrodeposited onto an inner surface of the cylindrical section in a state where the radial direction inner side of the cylindrical section that constitutes the hub is filled with the coating liquid, this coating liquid is drained to the exterior of this cylindrical section through the outside end opening of the cylindrical section, after which gas (such as air) may be blown into the outside end opening of this cylindrical section.
- As a result, when draining the coating liquid from the cylindrical section, even in the case where a film of the coating liquid is formed on the outside end opening section of this cylindrical section, the above coating liquid film can be ruptured by the gas blown into this outside end opening before the masking cover is separated from the outside end opening section of this cylindrical section. Therefore, when separating the masking cover from the outside end opening of the cylindrical section, a problem of splashing the coating liquid around the hub due to the coating liquid film ruptures can be prevented.
- Furthermore, when carrying out the invention mentioned above, a masking cover may be used, which has an entirely cylindrical shape, a section on the outer peripheral surface thereof close to a tip end that can be pressed against the entire inner periphery part of the outside end surface of the cylindrical section that constitutes the hub so as to be liquid-tight, and a liquid drain passage formed on a part of the tip end section able to enter within the cylindrical section that connects the outer peripheral surface and inner peripheral surface of the portion.
- As a result, having electrodeposited the coating particles in the coating liquid on the inner peripheral surface of this cylindrical section in a state where the radial direction inner side of this cylindrical section is filled with the coating liquid, and after draining this coating liquid to the exterior of the cylindrical section through the outside end opening of the cylindrical section, the coating liquid can be prevented from pooling in a gap section between the outer peripheral surface of the tip end section of the masking cover and the inner peripheral surface of the cylindrical section. Therefore, a problem of coating liquid pooled in the gap section falling on surrounding objects and splashing when separating the hub and the masking cover in the vertical direction while keeping the cylindrical section facing downward, and thereby becoming attached to sections other than the coated section on the surface of the hub, can be prevented.
- Furthermore, when carrying out the method of electrodeposition coating on a hub according to a second aspect of the present invention, as one of the respective processes, it is preferable to employ a process of electrodepositing the coating particles onto a section among the surfaces of the cylindrical section that is in contact with the coating liquid while only the cylindrical section is dipped in the coating liquid contained in a coating liquid tank having an open top section.
- As a result, when electrodepositing the coating particles onto the outer peripheral surface of the cylindrical section while only the cylindrical section is being dipped in the coating liquid contained in the coating liquid tank, undulation can be prevented from occurring on the surface of the coating liquid. Therefore, a coating film can be accurately formed in desired places on the outer peripheral surface of the cylindrical section.
- Moreover, when carrying out these embodiments of the present invention, for example, a plurality of coating devices at least provided with coating liquid tanks that contain the coating liquid, and having an open top end, are prepared, and one coating device is selected among the respective coating devices for each process, and the selected coating device is used to carry out the process.
- Furthermore, when carrying out the above invention a method may be adopted wherein, for example, one coating device provided with a coating liquid tank that contains coating liquid and that has an open top end, and a nozzle that sprays the coating liquid upwards is prepared, and each process is performed using only this coating device.
- Furthermore, when carrying out the present invention, for example, the relative positions of the liquid levels of the coating liquid contained in the coating liquid tank, and of the nozzle to the hub, and a way of spraying the coating liquid to be sprayed from this nozzle are changed for each of the steps.
-
FIG. 1 andFIG. 2 show anembodiment 1 of the present invention. In the present embodiment, a hubmain body 13 a that constitutes the wheelsupport hub unit 5 a shown inFIG. 26 mentioned above is an object of the embodiment. An inner peripheral surface of acylindrical section 16 that constitutes the hubmain body 13 a and a part of the outside end surface of the hubmain body 13 a, the circumference of which is surrounded by the cylindrical section 16 (the portion shown with the broken line α8 inFIGS. 1 and 2 andFIG. 27 (H)), is the surface to be coated. In order to form acoating film 31 on this surface to be coated (α8), first, preprocessing such as degreasing cleaning is carried out on this surface to be coated (α8). - Next, an operation of electrodepositing the coating particles on the surface to be coated (α8) is carried out. In the case of the present embodiment, when carrying out this operation, a closed end
cylindrical masking cover 32, which is made of rubber and has a top end opening, is used. That is, when carrying out the above operation, first, as shown inFIG. 1 , a top end surface of the maskingcover 32 is elastically pressed against the outside end surface of thecylindrical section 16 around the entire circumference thereof. Accordingly, the border section between the outside end surface of thecylindrical section 16 and the surface to be coated (α8) is separated so as to be liquid-tight. In this state, coatingliquid 28 is continuously supplied into the space surrounded by the surface to be coated (α8) and the inner surface of the maskingcover 32 through aliquid supply pipe 29 provided to pass through a center section of abottom section 33 of the maskingcover 32 so as to be liquid tight. As a result, the air in this space is drained to the exterior through adrain hole 34 provided on a portion on one section of thebottom section 33 away from theliquid supply pipe 29, and the above space is filled with thecoating liquid 28. Accordingly, thiscoating liquid 28 is brought into contact with the entire surface to be coated (α8). - Moreover, the
coating liquid 28 supplied from theliquid supply pipe 29 into the space is subsequently discharged to the exterior through theabove drain hole 34, and it is reused as thecoating liquid 28 to be supplied through theliquid supply pipe 29 into the space. As a result, in the case of the present embodiment, since thecoating liquid 28 is continuously supplied into the above space, liquid flow can be generated in this space, so that even if gas bubbles were to remain inside this space, these gas bubbles could be prevented from staying in one place of the surface to be coated (α8). - Once the
coating liquid 28 has come into contact with the entire surface to be coated (α8) as described above, subsequently, in this state, a voltage is applied between a first electrode (not shown in the diagram) installed in thecoating liquid 28 and a second electrode (not shown in the diagram) in contact with the hubmain body 13 a (for example, respectively, the first electrode side is connected to a positive pole and the second electrode side is connected to a negative pole). As a result, anundried coating film 31 is formed on the surface to be coated (α8) by ionizing the coating particles in thecoating liquid 28 and electrodepositing these ionized coating particles on the surface to be coated (α8). - Once the
undried coating film 31 has been formed on the surface to be coated (α8), subsequently, supply of thecoating liquid 28 from theliquid supply pipe 29 into the space is stopped and thecoating liquid 28 within the space is drained to the exterior through thedrain hole 34 as shown inFIG. 2 . Moreover, when thecoating liquid 28 within the space is drained to the exterior, the interior of this space becomes substantially a vacuum and a thin film of thecoating liquid 28 is formed on the outside end opening section of thecylindrical section 16, blocking this outside end opening section. While in this state, if the outside end surface of thecylindrical section 16 is separated from the top end surface of the maskingcover 32, at that moment the abovementioned thin film is rupture and drops of thecoating liquid 28 are splashed into an exterior space. The occurrence of such a phenomenon is not preferable in terms of maintaining the cleanliness of the exterior space and in terms of preventing thecoating liquid 28 from attaching to places other than the surface to be coated (α8) on the surface of the hubmain body 13 a. - Therefore, in the case of the present embodiment, once the coating
liquid 28 has been drained to the exterior from the space as described above, next, air ejected from a tip end section of anair nozzle 35 provided passing through a portion close to the top end of the maskingcover 32 is blown to the outside end opening section of thecylindrical section 16. As a result, the thin film of thecoating liquid 28 formed on the outside end opening section of thecylindrical section 16 is ruptured and a pressure inside the above space is brought close to (preferably equal to) the exterior pressure. Next, the outside end surface of thecylindrical section 16 is separated from the top end surface of the maskingcover 32, and by heating theundried coating film 31 to dry it, thecoating film 31 is baked onto the surface to be coated (α8). Lastly, thiscoating film 31 is cooled and the coating operation is complete. - As described above, in the case of the method of electrodeposition coating on a hub of the present embodiment, an operation of electrodepositing the coating particles on the surface to be coated (α8) is carried out while the surface to be coated (α8) is in contact with the
coating liquid 28, in a state where the border section between the surface to be coated (α8) and the area adjacent to this surface to be coated (α8) (outside end surface of the cylindrical section 16) is separated by the maskingcover 32 so as to be liquid-tight. Therefore, during this operation, thecoating liquid 28 in contact with the surface to be coated (α8) can be prevented from coming in contact with places other than this surface to be coated (α8) on the surface of the hubmain body 13 a. In particular, in the case of the present embodiment, the prevention effect described above can be achieved by only pressing the maskingcover 32 against the above border section so as to be liquid tight, and without having to attach masking tape to places other than this surface to be coated (α8). Therefore, in the case of the present embodiment, the operation of forming thecoating film 31 only on the surface to be coated (α8) can be easily carried out. - In the
embodiment 1 described above, in order to have the surface to be coated (α8) in contact with thecoating liquid 28, a method in which thecoating liquid 28 is supplied into the space surrounded by the surface to be coated (α8) and the inner surface of the maskingcover 32, filling the interior of this space with thecoating liquid 28, is employed. However, when carrying out the present invention, instead of this method, a method in which thecoating liquid 28 is continuously discharged upward with force from the top end opening of the aboveliquid supply pipe 29 to make this ejectedcoating liquid 28 continuously contact with the entire surface to be coated (α8) may also be employed. - Next,
FIG. 3 shows anembodiment 2 of the present invention. In the present embodiment, a hubmain body 13 that constitutes a wheelsupport hub unit 5 for a driving wheel shown inFIG. 25 mentioned above is an object of the embodiment. An inner peripheral surface of acylindrical section 16 that constitutes the hubmain body 13 and a radial direction outer half portion of a part of the outside end surface of the hubmain body 13, the circumference of which is surrounded by the cylindrical section 16 (the part shown with the broken line α9 inFIG. 3 ) is the surface to be coated. In the case of the present embodiment, the reason why a radial direction inner half portion of the part of the outside end surface of the hubmain body 13 surrounded by thecylindrical section 16 is not included in the surface to be coated is because this radial direction inner half portion is a bearing surface of a nut 25 (refer toFIG. 25 ) and if this radial direction inner half portion is subjected to electrodeposition coating, thenut 25 is likely to become loose. - Therefore, in the case of the present embodiment, when carrying out an operation of electrodepositing the coating particles on the surface to be coated (α9), as is the case with the
embodiment 1 described above, a border section separates the outside end surface of thecylindrical section 16 and the surface to be coated (α9) so as to be liquid-tight by elastically pressing the top end surface of the maskingcover 32 against the outside end surface of thecylindrical section 16 as shown in the diagram. Meanwhile, a top end surface of a rubber madesecond masking cover 36 supported and fixed on the top end section of theliquid supply pipe 29 is elastically pressed against the radial direction inner half portion of a part of the outside end surface of the hubmain body 13 surrounded by thecylindrical section 16. Thus, the border section between this radial direction inner half portion and the surface to be coated (α9) is separated by thesecond masking cover 36 so as to be liquid-tight, and an outside end opening of aspline hole 22 provided in the center section of the hubmain body 13 is blocked. Then, in this state, thecoating liquid 28 is continuously supplied through theliquid supply pipe 29 and through aliquid supply passage 37 provided in thesecond masking cover 36 into the space surrounded by the surface to be coated (α9) and the inner surface of the maskingcover 32. As a result, the air within this space is drained through thedrain hole 34 to the exterior and the interior of this space is filled with thecoating liquid 28. Consequently, thiscoating liquid 28 is brought into contact with the entire surface to be coated (α9). - In the case of the present embodiment, the tip end section of the
air nozzle 35 for blowing air after the completion of the operation of electrodepositing the coating particles on the surface to be coated (α9) in order to prevent the coating liquid from splashing, is arranged in an inside end section of the spline hole. When the electrodepositing operation is complete, the maskingcover 32 and thesecond masking cover 36 are lowered while compressed air is discharged from theair nozzle 35. At this time, the coating liquid attached on a contact section of the top surface of thesecond masking cover 36 and the outside end surface of the hubmain body 13 does not splash into the periphery thereof (particularly in the spline hole 22). Moreover, excessive coating liquid attached on the inner peripheral surface of thiscylindrical section 16 is collected into the maskingcover 32 by air flowing downward along the inner peripheral surface of thiscylindrical section 16. Other constructions and effects are similar to those of theembodiment 1 described above. - Furthermore, in the
embodiment 2 described above, thesecond masking cover 36 is supported and fixed on the top end section of theliquid supply pipe 29, however, when carrying out the present invention, thesecond masking cover 36 may also be supported and fixed on a separate supporting member. Moreover, with respect to theembodiment 2 described above, in the case of the present invention, by carrying out the electrodepositing operation while thecylindrical section 16 is dipped in coating liquid contained in a coating liquid tank instead of pressing the maskingcover 32 against the outside end surface of thecylindrical section 16, the coating particles can also be electrodeposited on the outside end surface and outer peripheral surface (the part dipped in the coating liquid) of thecylindrical section 16 in addition to the part shown with the broken line α9. - Next,
FIG. 4 andFIG. 5 show an embodiment 3 of the present invention. As is the case with theembodiment 1 shown inFIG. 1 andFIG. 2 , in the present embodiment, a hubmain body 13 b that constitutes the wheel support hub unit for a driven wheel is an object of the embodiment. However, in the case of the hubmain body 13 b, which is the object of the present embodiment, amale screw section 38 for screwing into a nut used for pressing the inside end surface of an inner ring 14 (refer toFIG. 26 ) is provided in an inside end section of this hubmain body 13 b. Also, in the case of the present embodiment, as with theembodiment 1 described above, an inner peripheral surface of acylindrical section 16 that constitutes the hubmain body 13 b and a part of the outside end surface of the hubmain body 13 b, the circumference of which is surrounded by the cylindrical section 16 (the part shown with the broken line α8 inFIG. 4 andFIG. 27 (H)), is the surface to be coated. - In the case of the present embodiment, a masking
cover 32 a used when carrying out the operation of electrodepositing the coating particles on the surface to be coated (α8) is constructed in a substantially cylindrical shape and is joined and fixed on a top end opening section of a closed-endedcylindrical container 39 manufactured from metal material. Accordingly, in the case of the present embodiment, theliquid supply pipe 29 is provided passing through the center section of abottom section 40 of thecontainer 39 so as to be liquid-tight. Moreover, thedrain hole 34 is provided in a part on thisbottom section 40 away from theliquid supply pipe 29. - Furthermore, in the case of the present embodiment, a top half section of the masking
cover 32 a is a conicalcylindrical section 41 inclined in a direction such that the radial dimension becomes smaller as it gets closer to the top side. An outer diameter dimension D41 of the greater diameter side end of this conicalcylindrical section 41 is greater than an inner diameter dimension d16 of the above cylindrical section 16 (D41>d16), and an outer diameter dimension d41 of the smaller diameter side end of this conicalcylindrical section 41 is smaller than the inner diameter dimension d16 of the cylindrical section 16 (d41<d16). Moreover,cutouts 42 that open on the smaller diameter side periphery are respectively provided in a plurality of places in a circumferential direction (six places in the example in the diagram) of a part of a smaller diameter side section of the conicalcylindrical section 41 the outer diameter dimension of which is smaller than the inner diameter dimension d16 of the cylindrical section 16 (the part on the radial direction inner side of the broken chain line inFIG. 5 ). In the case of the present embodiment, each of thesecutouts 42 respectively correspond to “oil discharging passages”. - In the case of the present embodiment, when carrying out the operation of electrodepositing the coating particles on the surface to be coated (α8), as shown in the diagram, the smaller diameter side end section of the conical
cylindrical section 41 that constitutes the maskingcover 32 a is inserted into the interior of thecylindrical section 16, and the outer peripheral surface of this conicalcylindrical section 41 is elastically pressed against the border section between the outside end surface of thiscylindrical section 16 and the surface to be coated (α8). As a result, this border section is made liquid-tight. In this state, thecoating liquid 28 is continuously supplied through theliquid supply pipe 29 into the space surrounded by the surface to be coated (α8) and the inner surfaces of the maskingcover 32 a and thecontainer 39. As a result, the air within this space is drained through thedrain hole 34 to the exterior, and the interior of this space is filled with thecoating liquid 28. Consequently, thiscoating liquid 28 is brought into contact with the entire surface to be coated (α8). - In the case of the present embodiment, since the smaller diameter side end section of the
conical cylinder section 41 is inserted into the interior of thecylindrical section 16, an annularliquid pool section 43 whose cross section is triangular shaped is formed between the outer peripheral surface of the conicalcylindrical section 41 and the inner peripheral surface of thecylindrical section 16, and the coating liquid 28 pools in thisliquid pool section 43. However, thecoating liquid 28 pooled in thisliquid pool section 43 is drained to the radial direction inner side of the conicalcylindrical section 41 through the inner sides of therespective cutouts 42 when thecoating liquid 28 in the space is drained to the exterior through thedrain hole 34. As a result, in the case of the present embodiment, thereafter, when the inner periphery of the outside end section of thecylindrical section 16 is separated from the outer peripheral surface of the conicalcylindrical section 41, defacement of the surrounding sections by the coating liquid due to thecoating liquid 28 pooled in theliquid pool section 43 can be prevented. On the other hand, if therespective cutouts 42 are not formed, as shown with an arrow inFIG. 6 , there would be a problem of thecoating liquid 28 pooled in theliquid pool section 43 dripping from the outside end periphery of thecylindrical section 16 to the outer peripheral surface of the conicalcylindrical section 41 and so forth, and furthermore, of splash-back from these places and attachment onto parts on the surface of the hubmain body 13 b other than the surface to be coated (α8). Other constructions and effects are similar to those of theembodiment 1 shown inFIG. 1 andFIG. 2 described above. - Next,
FIG. 7 shows an embodiment 4 of the present invention. In the case of the present embodiment, the tip end section (top end section inFIG. 7 ) of theair nozzle 35 provided passing through thebottom section 40 of thecontainer 39 so as to be liquid-tight is arranged on the radial direction inner side of thecylindrical section 16 that constitutes the hubmain body 13 b. Meanwhile, the top end opening of theair nozzle 35 is made to oppose to the outside end surface of the hubmain body 13 b. As a result, the air ejected from the top end opening of theair nozzle 35 is made to flow along the outside end surface of the hubmain body 13 b and the inner peripheral surface of thecylindrical section 16 to blow from above on the coating liquid pooled in theliquid pool section 43. Accordingly the coating liquid pooled in thisliquid pool section 43 is able to be easily drained to the radial direction inner side of this maskingcover 32 a through the plurality ofcutouts 42 provided in the top end edge of the maskingcover 32 a. Other constructions and effects are similar to those of the embodiment 3 described above. - Next,
FIG. 8 shows anembodiment 5 of the present invention. In the case of the present embodiment, the outside end surface and inner peripheral surface of thecylindrical section 16 that constitutes the hubmain body 13 b, and a part of the outside end surface of the hubmain body 13 a, the circumference of which is surrounded by the cylindrical section 16 (the part shown with the broken line α7 inFIG. 8 andFIG. 27 (G)), is the surface to be coated. Accordingly, in the case of the present embodiment, when carrying out the operation of electrodepositing the coating particles on this surface to be coated (α7), as shown in the diagram, the part close to the top end of the inner peripheral surface of the maskingcover 32 b, which is constructed in a substantially cylindrical shape, is elastically pressed against the entire outer periphery part of the outside end surface of thecylindrical section 16. Accordingly, the border section between the surface to be coated (α7) and the outer peripheral surface of thecylindrical section 16 is separated so as to be liquid tight. Other constructions and effects are similar to those of the embodiment 3 shown inFIG. 4 described above. - Next,
FIG. 9 shows anembodiment 6 of the present invention. In the case of the present embodiment, when carrying out the operation of electrodepositing the coating particles on the surface to be coated (α7) of the hubmain body 13 a, as shown in the diagram, the top end edge part of the maskingcover 32 c, which is constructed in a substantially cylindrical shape, is made to oppose closely the entire outer periphery part of the outside end surface of thecylindrical section 16 that constitutes the hubmain body 13 a with an interval of approximately 0.5 mm for example. The electrodepositing operation is carried out, while allowing a small amount of thecoating liquid 28 that has filled the space surrounded by the maskingcover 32 c and the hubmain body 13 a to flow out into the exterior space through aminute gap 45 formed between the top end edge part of the maskingcover 32 c and the outer periphery part of the outside end surface of thecylindrical section 16. - In the case of the present embodiment in which the electrodepositing operation is carried out in this way, since the space (interior space) surrounded by the masking
cover 32 c and the hubmain body 13 a and the exterior space are connected via theminute gap 45, even if thecoating liquid 28 filled in the space is drained to the exterior through a drain hole (not shown in the diagram), this interior space does not become vacuum. As a result, thereafter, when separating the maskingcover 32 andcylindrical section 16 from each other, a problem of thecoating liquid 28 attached on the surface to be coated (α7) splashing around can be prevented. Other constructions and effects of the other parts are similar to those of theembodiment 5 described above. - Moreover, in the
embodiment 6 described above, when carrying out the electrodepositing operation, the top end edge part of the maskingcover 32 c is closely opposed to the entire outer periphery part of the outside end surface of thecylindrical section 16, however, instead of this, even in the case where only one part in the circumferential direction is closely opposed and the remaining part in the circumferential direction is liquid-tightly pressed, a similar effect can be achieved. This also applies to theembodiments 1 to 4 described above. - Next,
FIG. 10 shows an embodiment 7 of the present invention. In the case of the present embodiment, an outer peripheral surface of an outside half section and outside end surface of thecylindrical section 16 that constitutes the hubmain body 13 b (the part shown with the broken line α2 inFIG. 10 andFIG. 27 (B)) is the surface to be coated. In the case of the present embodiment, when carrying out the operation of electrodepositing the coating particles on this surface to be coated (α2), as is the case with the conventional method shown inFIG. 28 and described above, the outside half section of the cylindrical section is dipped in thecoating liquid 28 contained in acoating liquid tank 27 a. However, in the case of the present embodiment, this dipping operation is carried out with the inner periphery part of the outside end surface of thecylindrical section 16 elastically pressed against the entire outer peripheral surface of a maskingcover 32 d constructed in a closed-ended conical cylindrical shape. Thus, during this dipping operation, the surface to be coated (α2) and the inner peripheral surface of thecylindrical section 16 are separated by the border section so as to be liquid-tight, so that the inner peripheral surface of thiscylindrical section 16 does not come into contact with thecoating liquid 28. The maskingcover 32 d is supported and fixed on a top surface of a supportingbase 44 fixed to thecoating liquid tank 27 a. - Moreover, in the case of the present embodiment, due to the
coating liquid 28 being supplied and drained into thecoating liquid tank 27 a through theliquid supply pipe 29, the position of the liquid level of thecoating liquid 28 contained in thiscoating liquid tank 27 a can be raised or lowered. In the case of the present embodiment, when pressing the inner periphery part of the outside end surface of thecylindrical section 16 against the outer peripheral surface of the maskingcover 32 d in order to carry out the operation of electrodepositing the coating particles on the surface to be coated (α2) as described above, the position of the level of the coating liquid is set lower than the bottom surface of the maskingcover 32 d. Then after the masking cover has been pressed as described above, the liquid level is raised up to the level of the top end edge of thecoating liquid tank 27 a as shown in the drawing (thecoating liquid 28 is overflowed above this top end edge). Moreover, after completion of the above electrodepositing operation, the position of the liquid level is lowered to below the bottom surface of the maskingcover 32 d, and then the inner periphery part of the outside end surface of thecylindrical section 16 is separated from the outer peripheral surface of the maskingcover 32 d. Other constructions and effects are similar to those of the respective embodiments described above. - In the respective embodiments described above, a method is employed in which the operation of forming a coating film by electrodeposition coating is carried out for a single hub body prior to assembly of a wheel support hub unit. However, in the case of carrying out a method of electrodeposition coating on a hub according to the first aspect of the present invention, as is the case with the conventional method shown in
FIG. 28 and described above, the operation of forming the coating film by means of electrodeposition coating may also be carried out for an assembled wheel support hub unit. -
FIG. 11 andFIG. 12 show anembodiment 8 of the present invention. In the present embodiment, the hubmain body 13 a that constitutes the wheelsupport hub unit 5 a shown inFIG. 26 and described above is the object of the embodiment, and electrodeposition coating is carried out on the outside end portion to middle portion of the outer peripheral surface, and the outside end surface and inner peripheral surface of thecylindrical section 16 that constitutes this hubmain body 13 a, and on the part of the outside end surface of the hubmain body 13 a, the circumference of which is surrounded by the cylindrical section 16 (the part shown with the broken line α6 inFIG. 11 andFIG. 12 and inFIG. 27 (F)). Therefore, in the case of the present embodiment, first, degreasing cleaning is carried out on the part shown with the broken line α6, and then preprocessing such as chromate treatment is carried out as necessary (this may be omitted). Next, the operation of electrodepositing the coating particles on the part shown with the broken line α6 is carried out. In the case of the present embodiment, this operation is carried out in two separate processes (first process, second process). - An operation of the first step is carried out using a
coating device 46 shown inFIG. 30 mentioned above (hereinafter, referred to as “first coating device 46”). Specifically, as shown inFIG. 11 , the entire outside end surface of thecylindrical section 16 that constitutes the hubmain body 13 a is brought into contact with the surface of thecoating liquid 28 filled in acoating liquid tank 48 that constitutes thisfirst coating device 46. Meanwhile, an outer surface of aguide section 53 provided on a top end section of anozzle 52 is made to oppose across its entirety the part of the outside end surface of this hubmain body 13 a, the circumference of which is surrounded by thecylindrical section 16, and the inner peripheral surface of thiscylindrical section 16. In this state, by ejectingcoating liquid 47 upwards from the top end opening of thisnozzle 52, this ejectedcoating liquid 47 is made to flow through a gap part between the abovementioned surfaces opposing to each other, in a state where this gap part is entirely filled with thecoating liquid 47. Thus, thiscoating liquid 47 is brought into contact respectively with the entire part of the outside end surface of the hubmain body 13 a, the circumference of which is surrounded by thecylindrical section 16, and with the entire inner peripheral surface of thiscylindrical section 16. - Moreover, having passed the gap part between the surfaces opposing to each other, the
coating liquid 47 discharged upwards from the top end opening of thenozzle 52 as described above is poured into thecoating liquid 47 filled in thecoating liquid tank 48. Then the coatingliquid 47 in thecoating liquid tank 48 overflows by the amount that has been poured in this way to the exterior from the top end edge of thecoating liquid tank 48. Thecoating liquid 47 overflowed like this is recovered by arecovery tank 49 that constitutes thefirst coating device 46, and it is re-used as thecoating liquid 47 to be discharged from the top end opening of thenozzle 52. This method of using thecoating liquid 47 is commonly used in all of the coating devices used in the present embodiment and in embodiments 9 to 11 described later. In the example shown in the diagram, since the outside end surface of thecylindrical section 16 is in contact with the surface of thecoating liquid 47 filled in thecoating liquid tank 48 as described above, thecoating liquid 47 splashed into the place on this surface into which thecoating liquid 47 is poured can be prevented from splashing into the space out of thecylindrical section 16. - As described above, once the outside end surface and inner peripheral surface of the
cylindrical section 16 and the part of the outside end surface of the hubmain body 13 a, the circumference of which is surrounded by thecylindrical section 16 have been brought into contact with thecoating liquid 47, subsequently, in this state, an electric voltage is applied between an electrode not shown in the diagram that is in contact with another part of thiscoating liquid 47 and the hubmain body 13 a (for example, this electrode side is connected to a positive pole and the hubmain body 13 a side is connected to a negative pole). As a result, by ionizing the coating particles in thecoating liquid 47 and electrodepositing these ionized coating particles on the part in contact with thecoating liquid 47, anundried coating film 54 is formed on this part. The operation up to here is the operation of the first process. - Having completed the operation of the first process in as described above, the process proceeds to the operation of the second process. The operation of this second process is carried out using a
second coating device 46 a such as is shown inFIG. 12 . A basic construction of this second coating device is substantially the same as that of the first coating device mentioned above. However, in the case of thesecond coating device 46 a, the shape of a top end section of anozzle 52 a is a simple cylindrical shape, and a top end edge of thisnozzle 52 a is arranged below the liquid level of thecoating liquid 47 filled in thecoating liquid tank 48. - When carrying out the second process using this
second coating device 46 a, thecoating liquid 47 is continuously supplied into thecoating liquid tank 48 from the top end opening of thenozzle 52 a. As a result, while thecoating liquid 47 filled in thecoating liquid tank 48 is overflowed to the exterior from the top end edge of thiscoating liquid tank 48, the outside end portion to middle portion of thecylindrical section 16 that constitutes the hubmain body 13 a is dipped in thecoating liquid 47. The reason for dipping thecylindrical section 16 while thecoating liquid 47 is overflowed is to maintain a constant position of the liquid level of thiscoating liquid 47 and to appropriately regulate a range to be coated on the outer peripheral surface of thecylindrical section 16. Moreover, in the case of the present embodiment, in order to reduce the likelihood of undulation occurring on the part on radial direction outer side of thecylindrical section 16, the top end opening of thenozzle 52 a is arranged on the radial direction inner side of thecylindrical section 16 and thecoating liquid 47 is gently discharged from the top end opening of thisnozzle 52 a. - Once the outside end surface and the outside end portion to middle portion of the outer peripheral surface and inner peripheral surface of this
cylindrical section 16 have been brought into contact with thecoating liquid 47 by dipping the outside end portion to middle portion of thecylindrical section 16 in thecoating liquid 47 filled in thecoating tank 48 as descried above, subsequently, in this state, an electric voltage is applied between an electrode not shown in the diagram that is in contact with another part of thecoating liquid 47 and the hubmain body 13 a (for examples this electrode side is connected to a positive pole and the hubmain body 13 a side is connected to a negative pole). As a result, by ionizing the coating particles in thecoating liquid 47 and electrodepositing these ionized coating particles on the part in contact with thecoating liquid 47, anundried coating film 54 is formed on this part. The operation up to here is the operation of the second step. - Once the
undried coating film 54 has been formed entirely on the part shown with the broken line α6 as described above, thereafter, thiscoating film 54 is baked onto the abovementioned surface by heating thisundried coating film 54 to dry it, and then thiscoating film 54 is cooled down to complete the coating operation. - As described above, in the case of the method of electrodeposition coating on a hub of the present embodiment, the operation of pouring the
coating liquid 47 discharged from the top end opening of thenozzle 52 on the part of the outside end surface of the hubmain body 13 a, the circumference of which is surrounded by thecylindrical section 16 and on the inner peripheral surface of the cylindrical section 16 (first process) and the operation of dipping the outside end portion to middle portion of thecylindrical section 16 in thecoating liquid 47 filled in the coating liquid tank 48 (second process) are separately carried out. As a result, when carrying out the operation of this second process, a problem of thecoating liquid 47 discharged from the top end opening of the nozzle 52 (52 a) being poured down on thecoating liquid 47 filled in thecoating liquid tank 48 causing undulations on thiscoating liquid 47 can be prevented. Therefore, when carrying out the operation of the second process, the state in which the outside end portion to middle portion of the outer peripheral surface of thecylindrical section 16 is in contact with thecoating liquid 47 can be stabilized. As a result, in the case of the present embodiment, thecoating film 54 can be accurately formed on the entire part shown with the broken line α6 including the outside end portion to middle portion of the outer peripheral surface of thecylindrical section 16. -
FIG. 13 andFIG. 14 show an embodiment 9 of the present invention. In the present embodiment, the hubmain body 13 that constitutes the wheelsupport hub unit 5 shown inFIG. 25 and described above is the object of the embodiment, and electrodeposition coating is done on the outside end portion to middle portion of the outer peripheral surface, the outside end surface and inner peripheral surface of thecylindrical section 16 that constitutes this hubmain body 13, and on the radial direction outer half portion of the part of the outside end surface of the hubmain body 13, the circumference of which is surrounded by the cylindrical section 16 (the part shown with the broken line α4 inFIG. 13 andFIG. 14 and inFIG. 27 (F)). The reason for not carrying out electrodepositing on the radial direction inner half portion of the part on the outside end surface of the hubmain body 13, the circumference of which is surrounded by the cylindrical section is that this radial direction inner half portion is a bearing surface of a nut 25 (refer toFIG. 25 ) and if this radial direction inner half section is subjected to electrodeposition coating, thenut 25 is likely to become loose. - Consequently, in the case of the present embodiment, in order not to have the
coating liquid 47 discharged from the top end section of thenozzle 52 b that constitutes afirst coating device 46 b come into contact with the radial direction inner half section when carrying out the operation of the first process as shown inFIG. 13 (and furthermore in order not to have thecoating liquid 47 come into contact with the inner peripheral surface of a spline hole 22), the radial direction inner half section and an outside end opening of thespline hole 22 are covered by a maskingcover 55. This maskingcover 55 is manufactured from elastic materials such as rubber and synthetic resin, in a truncated cone shape, and abottom plate section 56, which is an end section on a smaller diameter side (down side inFIG. 13 ), is supported and fixed on the top end section of thenozzle 52 b, and its opening periphery on a greater diameter side (upper side inFIG. 13 ) is pressed entirely against the outside end surface of the hubmain body 13 so as to be liquid-tight. Moreover, amesh section 57 through which thecoating liquid 47 can pass freely is provided in a part between the maskingcover 55 and theguide section 53 around the entire circumference on the top end section of thenozzle 52 b. Thecoating liquid 47 can be discharged from the top end section of thenozzle 52 b through thismesh section 57. In the case of the present embodiment, as is the case with theembodiment 8 described above, the operation of the following second step is carried out using thesecond coating device 46 a as shown inFIG. 14 . Other constructions and effects are similar to those of theembodiment 8 described above. - Next,
FIG. 15 andFIG. 16 show anembodiment 10 of the present invention. In theembodiment 8 shown inFIG. 11 andFIG. 12 mentioned above, a method of carrying out the operation of the first process and the operation of the second process respectively usingdifferent coating devices coating device 46 c such as is shown inFIG. 15 andFIG. 16 is employed. The basic construction of thecoating device 46 c used in the present embodiment is substantially the same as that of thefirst coating device 46 used in theembodiment 8 mentioned above. However, in the case of thecoating device 46 c of the present embodiment, thenozzle 52 can be shifted in an axial direction (vertical direction inFIG. 15 andFIG. 16 ) with respect to thecoating liquid tank 48 and therecovery tank 49. Therefore, in the case of the present embodiment,annular sealing devices 60 are respectively installed on the inner peripheries of throughholes bottom plate sections coating liquid tank 48 and therecovery tank 49, and the inner peripheries of therespective sealing devices 60 are respectively brought into contact with an outer peripheral surface of a middle section of thenozzle 52 to secure sufficient sealing while allowing sliding in the axial direction. - In the case of the present embodiment, when carrying out the operation of the first process using the coating device 26 c, as shown in
FIG. 15 , the top end opening of thenozzle 52 is arranged above the surface of thecoating liquid 47 filled in thecoating liquid tank 48. In this state, as shown in the same diagram, the operation of the first process is carried out in a similar manner to theembodiment 8 described above. Subsequently, when carrying out the operation of the second process, as shown inFIG. 15 andFIG. 16 , by shifting the top end opening of thenozzle 52 downward, the top end opening of thisnozzle 52 is arranged below the liquid surface of thecoating liquid 47 filled in thecoating liquid tank 48. Meanwhile, by shifting either one of thecoating device 46 c or the hubmain body 13 a, or both of them in a direction such that they move relatively closer to each other in the axial direction (vertical direction inFIG. 15 andFIG. 16 ), the outside end portion to middle portion of thecylindrical section 16 that constitutes the hubmain body 13 a is dipped in thecoating liquid 47. In this state, as shown inFIG. 16 , the operation of the second process is carried out in a similar manner to theembodiment 8 described above. - In the case of the present embodiment described above, since the operations of the first and second processes are carried out using the
single coating device 46 c, a reduction in operation time, operation space and cost of the operation device can be achieved compared to the case of theembodiment 8 described above. Other constructions and effects are similar to those of theembodiment 8 described above. - Next,
FIG. 17 andFIG. 18 show an embodiment 11 of the present invention. In the embodiment 9 shown inFIG. 13 andFIG. 14 mentioned above, a method of carrying out the operation of the first process and the operation of the second process respectively using thedifferent coating devices coating device 46 d such as is shown inFIG. 17 andFIG. 18 is employed. The basic construction of thecoating device 46 d used in the present embodiment is substantially the same as that of thefirst coating device 46 b used in the embodiment 9 mentioned above. However, in the case of thecoating device 46 d of the present embodiment, thenozzle 52 b can be shifted in an axial direction (vertical direction inFIG. 17 andFIG. 18 ) with respect to thecoating liquid tank 48 and therecovery tank 49. Therefore, in the case of the present embodiment,annular sealing devices 60 are respectively installed on the inner peripheries of throughholes bottom plate sections coating liquid tank 48 and therecovery tank 49, and the inner peripheries of therespective sealing devices 60 are respectively brought into contact with an outer peripheral surface of a middle section of thenozzle 52 b to secure sufficient sealing while allowing sliding in the axial direction. - In the case of the present embodiment, when carrying out the operation of the first process using the
coating device 46 d, as shown inFIG. 17 , themesh section 57 being the top end opening of thenozzle 52 b is arranged above the liquid surface of thecoating liquid 47 filled in thecoating liquid tank 48. In this state, as shown in the same diagram, the operation of the first step is carried out in a similar manner to the embodiment 9 described above. Subsequently, when carrying out the operation of the second process, as shown inFIG. 17 andFIG. 18 , by shifting thenozzle 52 b downward, theguide section 53 and themesh section 57 provided on the top end portion of thisnozzle 52 b are arranged below the liquid level of thecoating liquid 47 filled in thecoating liquid tank 48. However, at this time, at least the top end section of the maskingcover 55 is arranged above the liquid level of thecoating liquid 47 so as not to allow thecoating liquid 47 to enter the interior (in a concaved section provided on the top surface) of this maskingcover 55. Meanwhile, by shifting either one of thecoating device 46 d or the hubmain body 13, or both of them in a direction such that they move relatively closer to each other in the axial direction (vertical direction inFIG. 17 andFIG. 18 ), the outside end portion to middle portion of thecylindrical section 16 that constitutes the hubmain body 13 is dipped in thecoating liquid 47. In this state, as shown inFIG. 18 , the operation of the second process is carried out in a similar manner to the embodiment 9 described above. - In the case of the present embodiment described above, since the operations of the first and second processes are carried out using the
single coating device 46 d, a reduction in operation time, operation space and cost of the operation device can be achieved compared to the case of the embodiment 9 described above. Other constructions and effects are similar to those of the embodiment 9 described above. - In the
embodiments 8 to 11 described above, as thenozzles coating devices nozzles guide section 53 provided on the top end sections thereof are used, however, thisguide section 53 may be omitted. This also applies to thenozzle 52 that constitutes thecoating device 46 shown inFIG. 30 described above. - Moreover, in the
embodiments 8 to 11 mentioned above, the method of electrodeposition coating on a hub according to the second aspect of the present invention is carried out for a hub (hubmain body 13 a) that constitutes a wheelsupport hub unit 5 a for a driven wheel shown inFIG. 26 mentioned above, and for a hub (hub main body 13) that constitutes a wheelsupport hub unit 5 for a driving wheel shown inFIG. 25 mentioned above. However, the method of electrodeposition coating on a hub according to the second aspect of the present invention is not limited to these and may also be carried out for a hub that constitutes a wheel support hub unit having various kinds of structure (including one in which an outside inner ring raceway is directly formed on the middle section of the outer peripheral surface of the hub, and one in which this outside inner ring raceway is formed on the outer peripheral surface of a separate inner ring that is fitted onto the middle section of the hub). - Furthermore, in the
embodiments 8 to 11 described above, a method is employed in which the operation of forming a coating film by electrodeposition coating is carried out for a single hub body prior to assembly of a wheel support hub unit. However, in the case of carrying out the method of electrodeposition coating on a hub according to the second aspect of the present invention, the operation of forming the coating film by means of electrodeposition coating may also be carried out for an assembled wheel support hub unit. - When manufacturing the respective wheel
support hub units FIG. 25 andFIG. 26 mentioned above, by carrying out a forging process such as rolling press processing to a cylindrical section present at an inside end section of the hubmain bodies section 19 in this part. In the case where the operation of forming such acrimped section 19 is carried out after carrying out any of theembodiments 8 to 11 described above for example, if the part on which thecoating film 54 has been formed (for example, the part of the outside end surface of the respective hubmain bodies cylindrical section 16 and the inner peripheral surface of this cylindrical section 16) is employed as an abutment (a surface that comes in contact with a seat), the force applied during processing may peel off thecoating film 54. Therefore, in order to prevent this kind of problem from occurring, it is preferable that a part on which thecoating film 54 is not formed (for example, an outside surface of an attachment flange 15) be employed as the abutment. -
FIG. 19 toFIG. 22 show anembodiment 12 of the present invention. In the present embodiment the hubmain body 13 a shown inFIG. 19 is an object of the embodiment. The hubmain body 13 a is a constructing member of the wheelsupport hub unit 5 a shown inFIG. 26 mentioned above. In the example shown in the diagram, a high frequency hardening processing is applied to the entirety of the middle section of the outer peripheral surface of the hubmain body 13 a including aninner ring raceway 17 a (the part shown in cross hatching pattern) to form ahardened layer 61 on this part. By forming such ahardened layer 61, the durability of the hubmain body 13 a is increased. - In the case of the present embodiment, electrodeposition coating is carried out on the outer peripheral surface, inner peripheral surface and outside end surface of the
cylindrical section 16 provided on the outside end section of the hubmain body 13 a, and the radial direction middle section of the outside end surface of this hubmain body 13 a (the part shown with the broken line α inFIG. 19 ). Therefore in the case of the present embodiment, first, a predetermined preprocessing such as degreasing cleaning is carried out on the part shown with the broken line α, and then with this part shown with the broken line α in contact with (dipped in) the coating liquid (not shown in the diagram), an electric voltage is applied between an electrode (not shown in the diagram) in contact with another part of this coating liquid and another electrode (not shown in the diagram) in contact with the hubmain body 13 a (the coating liquid side is connected to a positive pole and the hubmain body 13 a side is connected to a negative pole). As a result, by ionizing the coating particles in the coating liquid and electrodepositing these ionized coating particles on the part shown with the broken line α, anundried coating film 62 is formed on this part. In the example shown in the diagram, thiscoating film 62 is shown with a heavy line for the sake of simplicity, however, the width of this heavy line does not represent the thickness of thiscoating film 62. The actual thickness of thecoating film 62 is, for example, approximately several μm after being subjected to baking, depending on the length of time for which the above mentioned electric voltage has been applied. - Then, having formed the
undried coating film 62 as described above, thisundried coating film 62 is heated using far-infrared radiation emitted from aceramic heater 63 as shown inFIG. 21 . As a result, theundried coating film 62 is dried and thiscoating film 62 is baked onto the surface of the hubmain body 13 a. In the case of the present embodiment, the temperature to which thecoating film 62 is heated at this time is no greater than 140° C. - Once the
coating film 62 has been baked onto the surface of the hubmain body 13 a as described above, subsequently, thiscoating film 62 is cooled down by blowing cold air ejected from a cooler 64 onto thecoating film 62, as shown inFIG. 22 , to complete the coating operation. - As described above, in the case of the method of electrodeposition coating on a hub according to the present embodiment, the heating temperature of the
undried coating film 62 is low, no greater than 140° C. As a result, even in the case where the heat applied to thiscoating film 62 is transmitted to thehardened layer 61 formed on the middle section of the outer peripheral surface of the hubmain body 13 a, the temperature of thishardened layer 31 does not excessively rise (does not rise to a temperature where a softening effect such as annealing or tempering starts to occur in this hardened layer 61). Therefore, in the case of the present embodiment, when forming thecoating film 62, a decrease in the hardness of thehardened layer 61 can be prevented. - Next,
FIG. 23 andFIG. 24 show anembodiment 13 of the present invention. In the case of the present embodiment, a procedure of the operation for forming theundried coating film 62 on the part shown with the broken line α inFIG. 19 mentioned above, as shown inFIG. 20 mentioned above, by electrodepositing ionized coating particles on the part in question, is similar to that in the case of theembodiment 12 described above. - In the case of the present embodiment, having formed the
undried coating film 62 as described above, cold air ejected from a cooler 64 a is blown onto the middle section (the part on which the hardenedlayer 61 has been formed) to the inside end section of the hubmain body 13 a as shown inFIG. 23 . Thus, while cooling down this part, theundried coating film 62 is heated by the far-infrared radiation emitted from theceramic heater 63. As a result, thecoating film 62 is dried and thiscoating film 62 is baked onto the surface of the hubmain body 13 a. In the case of the present embodiment, the heating temperature of thecoating film 62 at this time is regulated within a range of 140° C. to 220° C. - Then, once the
coating film 62 has been baked onto the surface of the hubmain body 13 a as described above, subsequently, thecoating film 62 is cooled down by blowing cold air discharged from the cooler 64 a on the middle section to the inside end section (the section on which the hardenedlayer 61 is formed) of the hubmain body 13 a, while cold air discharged from the cooler 64 is directly blown onto thecoating film 62, to complete the coating operation. - As described above, in the case of the method of electrodeposition coating on a hub according to the present embodiment, the heating temperature for the
undried coating film 62 is raised comparatively high within a range from 140° C. to 220° C., however, the operation of heating theundried coating film 62 is carried out while cooling the middle section to the inside end section of the hubmain body 13 a. As a result, an increase in the temperature of thehardened layer 61 due to the heat applied to thecoating film 62 can be suppressed. Therefore, an excessive increase in the temperature of thehardened layer 61 can be prevented (such that it does not rise to the temperature where a softening effect such as annealing or tempering starts to occur in this hardened layer 61). As a result, in the case of the present embodiment also, when forming thecoating film 62, a decrease in the hardness of thehardened layer 61 can be prevented. Furthermore, in the case of the present embodiment, since the heating temperature of theundried coating film 62 is raised comparatively high, a length of time required for baking thiscoating film 62 can be shortened compared to the case of theembodiment 12 described above. - Moreover, in the
embodiments main body 13 a) that constitutes the wheel support hub unit for a driven wheel shown inFIG. 26 mentioned above. However, the method of electrodeposition coating on a hub according to the third and fourth aspects of the present invention may also be carried out for a hub (hub main body 13) that constitutes the wheelsupport hub unit 5 for a driving wheel shown inFIG. 25 mentioned above. Furthermore, the method of electrodeposition coating on a hub is not limited to this and may also be carried out for a hub that constitutes a wheel support hub unit that has various kinds of structure (including one in which an outside inner ring raceway is directly formed on the middle section of the outer peripheral surface of the hub, and one in which this outside inner ring raceway is formed on the outer peripheral surface of a separate inner ring that externally engages with the middle section of the hub). - Furthermore, in the
embodiments 12 to 13 described above, a method is employed in which the operation of forming a coating film by electrodeposition coating is carried out for a single hub body prior to assembly of a wheel support hub unit. However, in the case of carrying out the method of electrodeposition coating on a hub according to the third and fourth aspects of the present invention, the operation of forming the coating film by means of electrodeposition coating may also be carried out for an assembled wheel support hub unit. In the case of carrying out the method of electrodeposition coating on a hub for an assembled wheel support hub unit as mentioned above, in addition to the effects described in theaforementioned embodiments - An antirust coating film can be accurately formed only within a desired range on a cylindrical section provided on an outside end section of a hub that constitutes a wheel support hub unit by means of electrodeposition coating, without using masking tape, and without influencing a part of an outer peripheral surface of the hub on which a hardened layer has been formed by means of high frequency hardening processing, nor grease enclosed in a rolling body installation section.
Claims (12)
1. A method of electrodeposition coating on a hub where in order to form a coating film on a desired range that includes at least one part of a surface of a cylindrical section among the surfaces of a hub that constitutes a wheel support hub unit that is respectively provided with an attachment flange on a part close to an outside end of an outer peripheral surface for supporting and fixing a wheel and a braking rotating member, and with the cylindrical section for externally engaging at least one of the wheel and the braking rotating member on an outside end section, coating particles in a coating liquid are electrodeposited on this desired range, with the desired range in contact with the coating liquids
wherein the operation of electrodepositing the coating particles on the desired range is carried out with a masking cover in contact with or closely opposing to a border part on the surface of the hub between the desired range and a range adjacent to this desired range.
2. A method of electrodeposition coating on a hub according to claim 1 , wherein a border sections which is to come into contact with, or closely oppose, the masking cover, is a periphery part of an outside end surface of a cylindrical section that constitutes the hub.
3. A method of electrodeposition coating on a hub according to claim 1 , wherein a hole that passes through the hub in an axial direction is provided in a center section of the hub, and a border section, which is to come into contact with, or closely oppose, the masking cover, is an annular section that surrounds an outside end opening of the hole of the outside end surface of the hub which is surrounded by the cylindrical section.
4. A method of electrodeposition coating on a hub according to claim 2 , wherein after coating particles in a coating liquid have been electrodeposited onto an inner surface of a cylindrical section that constitutes the hub in a state where a radial direction inner side of the cylindrical section is filled with the coating liquid, this coating liquid is drained to the exterior of this cylindrical section through an outside end opening of the cylindrical section, after which gas is blown into the outside end opening of this cylindrical section.
5. A method of electrodeposition coating on a hub according to claim 1 , wherein, as the masking cover, a masking cover is used, which has an entirely cylindrical shape, a section on the outer peripheral surface thereof close to a tip end that can be pressed against the entire inner periphery part of the outside end surface of the cylindrical section that constitutes the hub so as to be liquid-tight, and a liquid drained passage formed on a part of the tip end section able to enter within the cylindrical section that connects the outer peripheral surface and inner peripheral surface of said portion.
6. A method of electrodeposition coating on a hub where in order to form a coating film on a desired range that includes at least a surface of a cylindrical section among the surfaces of a hub that constitutes a wheel support hub unit that is respectively provided with an attachment flange on a part close to an outside end of an outer peripheral surface for supporting and fixing a wheel and a braking rotating member, and with the cylindrical section for externally engaging at least one of these wheel and braking rotating member on an outside end section, coating particles in a coating liquid are electrodeposited on this desired range, with the desired range in contact with the coating liquid,
wherein a plurality of partial ranges that respectively become a range of one part of the desired range are set, and the operation of electrodepositing said coating particles on the desired range is carried out in separate processes for each of said partial ranges.
7. A method of electrodeposition coating on a hub according to claim 6 , wherein one of the respective processes is a process of electrodepositing the coating particles onto a section among the surfaces of the cylindrical section that is in contact with the coating liquid while only the cylindrical section is dipped in the coating liquid contained in a coating liquid tank having an open top section.
8. A method of electrodeposition coating on a hub according to claim 6 , wherein a plurality of coating devices at least provided with coating liquid tanks that contain the coating liquid, and having an open top end, are prepared, and one coating device is selected among the respective coating devices for each process, and the selected coating device is used to carry out the process.
9. A method of electrodeposition coating on a hub according to claim 6 , wherein one coating device provided with a coating liquid tank that contains coating liquid and that has an open top end, and a nozzle that sprays the coating liquid upwards is prepared, and each step is performed using only this coating device.
10. A method of electrodeposition coating on a hub according to claim 9 , wherein relative positions of liquid levels of the coating liquid contained in the coating liquid tank and of the nozzle to the hub, and a way of spraying the coating liquid to be sprayed from this nozzle are changed for each of the steps.
11. A method of electrodeposition coating on a hub where, after forming an undried coating film on a surface of a cylindrical section among the surfaces of a hub that constitutes a wheel support hub unit respectively provided with an attachment flange on a part close to an outside end of an outer peripheral surface for supporting and fixing a wheel and a braking rotating member, and with the cylindrical section for externally engaging at least one of the wheel and the braking rotating member on an outside end section, by electrodepositing coating particles onto the surface, the coating film is baked onto the surface of the cylindrical section by heating the undried coating film to dry it,
wherein the heating temperature of the undried coating film is below 140° C.
12. A method of electrodeposition coating on a hub where, after forming an undried coating film on a surface of a cylindrical section among the surfaces of a hub that constitutes a wheel support hub unit respectively provided with an attachment flange on a part close to an outside end of an outer peripheral surface for supporting and fixing a wheel and a braking rotating member, and with the cylindrical section for externally engaging at least one of the wheel and the braking rotating member on an outside end section, by electrodepositing coating particles onto the surface, the coating film is baked onto the surface of the cylindrical section by heating the undried coating film to dry it,
wherein the heating temperature of the undried coating film is between 140° C. and 220° C., and the operation of heating the undried coating film is carried out while the hub is being cooled from an inside end side.
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
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JP2004367107A JP2006169608A (en) | 2004-12-20 | 2004-12-20 | Electrodeposition coating method for hub |
JP2004367107 | 2004-12-20 | ||
JP2004376005 | 2004-12-27 | ||
JP2004376005A JP2006183077A (en) | 2004-12-27 | 2004-12-27 | Electrodeposition coating method for hub |
JP2005007118 | 2005-01-14 | ||
JP2005007118A JP2006193788A (en) | 2005-01-14 | 2005-01-14 | Electrodeposition coating method for hub |
Publications (1)
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US20080190775A1 true US20080190775A1 (en) | 2008-08-14 |
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US11/765,549 Abandoned US20080190775A1 (en) | 2004-12-20 | 2007-06-20 | Method of electrodeposition coating on a hub |
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US (1) | US20080190775A1 (en) |
DE (1) | DE112005003201T5 (en) |
GB (1) | GB2435600B (en) |
WO (1) | WO2006068097A1 (en) |
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JPH0853798A (en) * | 1994-08-10 | 1996-02-27 | Toyota Motor Corp | Masking method for plating cylinder and device therefor |
JP2003136902A (en) * | 2001-10-31 | 2003-05-14 | Nsk Ltd | Hub unit bearing |
JP3889315B2 (en) * | 2002-05-23 | 2007-03-07 | 日本精工株式会社 | Electrodeposition coating method for automotive hubs |
-
2005
- 2005-12-19 DE DE112005003201T patent/DE112005003201T5/en not_active Ceased
- 2005-12-19 WO PCT/JP2005/023282 patent/WO2006068097A1/en active Application Filing
- 2005-12-19 GB GB0712396A patent/GB2435600B/en active Active
-
2007
- 2007-06-20 US US11/765,549 patent/US20080190775A1/en not_active Abandoned
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4240880A (en) * | 1978-07-25 | 1980-12-23 | Sumitomo Metal Mining Co., Ltd. | Method and apparatus for selectively plating a material |
US4283755A (en) * | 1980-02-05 | 1981-08-11 | The United States Of America As Represented By The Secretary Of The Air Force | Modulator multilayer detector |
US4675093A (en) * | 1985-01-31 | 1987-06-23 | Sumitomo Metal Mining Company Limited | Selectively plating apparatus for forming an annular coated area |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100301666A1 (en) * | 2008-01-23 | 2010-12-02 | Ntn Corporation | Bearing device for wheel |
US10092922B2 (en) * | 2017-02-25 | 2018-10-09 | Citic Dicastal Co., Ltd | Intelligent flexible hub powder spraying line and process |
Also Published As
Publication number | Publication date |
---|---|
WO2006068097A1 (en) | 2006-06-29 |
GB2435600B (en) | 2010-10-20 |
GB2435600A (en) | 2007-08-29 |
GB0712396D0 (en) | 2007-08-01 |
GB2435600A8 (en) | 2007-08-28 |
DE112005003201T5 (en) | 2007-10-31 |
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Owner name: NSK LTD., JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KAWAMURA, KATSUYUKI;INOUE, YOSHIO;ENDO, SATORU;AND OTHERS;REEL/FRAME:019705/0159;SIGNING DATES FROM 20070710 TO 20070711 Owner name: NSK LTD., JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KAWAMURA, KATSUYUKI;INOUE, YOSHIO;ENDO, SATORU;AND OTHERS;SIGNING DATES FROM 20070710 TO 20070711;REEL/FRAME:019705/0159 |
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STCB | Information on status: application discontinuation |
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