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Publication numberWO1999047287 A2
Publication typeApplication
Application numberPCT/US1999/005897
Publication date23 Sep 1999
Filing date18 Mar 1999
Priority date18 Mar 1998
Also published asWO1999047287A3, WO1999047287A8
Publication numberPCT/1999/5897, PCT/US/1999/005897, PCT/US/1999/05897, PCT/US/99/005897, PCT/US/99/05897, PCT/US1999/005897, PCT/US1999/05897, PCT/US1999005897, PCT/US199905897, PCT/US99/005897, PCT/US99/05897, PCT/US99005897, PCT/US9905897, WO 1999/047287 A2, WO 1999047287 A2, WO 1999047287A2, WO 9947287 A2, WO 9947287A2, WO-A2-1999047287, WO-A2-9947287, WO1999/047287A2, WO1999047287 A2, WO1999047287A2, WO9947287 A2, WO9947287A2
InventorsJohn L. Knapp
ApplicantHuynh, Oanh, Cai, Hue
Export CitationBiBTeX, EndNote, RefMan
External Links: Patentscope, Espacenet
Tube-forming machine and method
WO 1999047287 A2
Abstract
A tube-forming machine (10) permits the formation of tubing (14) from a flat strip of material (12) using a continuous in-line process. In this manner, tube (14) may be formed from flat strip material (12) without transferring the preformed strip from one set of former rolls to a second, third, fourth, and in some cases fifth set for further forming. The resulting tubing (14) is of a high quality and the properties of the material have been substantially preserved so that, if necessary, the output tubing (14) from the present tube-forming machine (10) may be further processed into a desired finished product.
Claims  (OCR text may contain errors)
CLAIMS I claim:
1. A tube-forming apparatus for forming a tube from a flat strip of material in a single operation, said apparatus comprising a payoff unit supplying said flat strip of material; a forming unit receiving said flat strip of material and creating said tube from said flat strip of material; and a tube puller advancing said material from said payoff unit and through said forming unit at a predetermined speed.
2. The tube-forming apparatus of claim 1, wherein said payoff unit comprises a vertically-oriented coil of said flat strip material, and further wherein said coil is rotatably mounted on a stand.
3. The tube-forming apparatus of claim 1 wherein said tube puller comprises a collection spool having an axis of rotation, an attachment cable fixed to said collection spool for rotation therewith, and a motor to rotate said collection spool.
4. The tube-forming apparatus of claim 3 wherein said collection spool further comprises a plurality of pins whose longitudinal axes are arranged substantially parallel to and radially spaced from said axis of rotation of said collection spool.
5. The tube-forming apparatus of claim 4, wherein said attachment cable comprises a first end fixedly mounted to said collection spool and a free end having a clamp mounted thereto, whereby, when said clamp is clamped upon said material, rotation of said collection spool by said motor pulls said material through said forming unit.
6. The tube-forming apparatus of claim 1 wherein said forming unit comprises a form box, a weld box, and a sink box.
7. The tube-forming apparatus of claim 6 wherein said form box comprises a first tube-forming die mounted adjacent an input end of said form box, a plug draw die mounted downstream of said tube-forming die, and a reduction die mounted downstream of said plug draw die, and wherein said form box further comprises a lubrication system.
8. The tube-forming apparatus of claim 7 wherein said forming unit further comprises a cleaning station downstream of said form box and upstream of said a weld box.
9. The tube-forming apparatus of claim 8 wherein said forming unit further comprises a wiping station downstream of said cleaning station and upstream of said a weld box.
10. The tube-forming apparatus of claim 9 wherein said lubrication system comprises a first lubrication network including a first lubricant reservoir, a first lubricant pump, a first lubricant supply line, at least one drip dispenser, a first pick-up drain, and a first lubricant return line.
11. The tube-forming apparatus of claim 9 wherein said lubrication system further comprises a first drip dispenser and a second drip dispenser, wherein said first drip dispenser dispenses lubricant upstream of said first tube-forming die and said second drip dispenser dispenses lubricant downstream of said first drip dispenser and upstream of said reduction die.
12. The tube-forming apparatus of claim 11 further comprising alignment plates upstream of said form box and downstream of said payoff unit.
13. The tube-forming apparatus of claim 12 further comprising a cooling and fume-extraction system downstream of said weld box and upstream of said sink box.
14. The tube-forming apparatus of claim 13 further comprising an air- pressure cooling tube downstream of said cooling and fume-extraction system and upstream of said sink box.
15. The tube-forming apparatus of claim 14, wherein said sink box comprises a final die and a second lubrication network.
16. The tube-forming apparatus of claim 15 wherein said second lubrication network further comprises a second lubricant reservoir, a second lubricant pump, a second lubricant supply line, a third drip dispenser, a second pickup drain, and a second lubricant return line.
17. The tube-forming apparatus of claim 9, wherein said lubrication system comprises a plurality of drip dispensers including a first drip dispenser and a second drip dispenser lubricating said material as it passes through said form box, and a third drip dispenser lubricating said material as it passes through said sink box.
18. The tube-forming apparatus of claim 16, wherein said weld box comprises a welding torch and a cyclomatic arc voltage control unit for said welding torch.
19. The tube-forming apparatus of claim 18, wherein said voltage control unit pulses an arc of said welding torch at approximately 2000 times per second.
20. The tube-forming apparatus of claim 19 wherein said weld box further comprises a cooling jacket having a fluid circulating therein.
21. The tube-forming apparatus of claim 20 wherein said cooling fluid is water that enters said cooling jacket through an input tube and exits said cooling jacket through an output tube.
22. The tube-forming apparatus of claim 21 wherein an air line is connected to said input tube adjacent said cooling jacket.
23. The tube-forming apparatus of claim 22 wherein each of said input tube, said output tube, and said air line has an on-off valve operably associated therewith.
24. The tube-forming apparatus of claim 23 wherein said cleaning station and said wiping station are self-aligning.
25. The tube-forming apparatus of claim 24, wherein said flat strip of material is stainless steel that is approximately 0.225 inches wide and approximately 0.004 inches thick, and further wherein said tube is approximately 0.070 inches in diameter and has approximately a 0.004 inches thick wall.
26. An in-line tube-forming apparatus comprising an input end and an output end, wherein a substantially flat strip of material, having an initial strip width, an initial strip thickness, and a strip longitudinal axis, enters said input end and then moves forwardly through said apparatus from said input end to said output end, wherefrom a final tube of said material, having a final outside diameter, a final wall thickness, and a tube longitudinal axis, exits.
27. The in-line tube-forming apparatus of claim 26 wherein said substantially flat strip of material further comprises a first longitudinal edge and a second longitudinal edge, and wherein said tube-forming apparatus further comprises a tube-forming die for bending said flat strip into an arc about an axis parallel to said stip longitudinal axis, said arc having an arc length of less than 360 degrees, said tube-forming die arranged between said input end and said output end, and positioned substantially adjacent said input end; a plug-draw die for increasing said arc length to substantially 360 degrees, bringing said first longitudinal edge adjacent said second longitudinal edge in a substantially abutting relationship, thereby forming a precursor tube having an initial diameter, said plug-draw die arranged between said tube-forming die and said output end; a welding means for welding said first longitudinal edge of said strip to said second longitudinal edge of said strip, thereby forming a tube from said precursor tube, said tube having an outside diameter, a wall thickness, and said tube longitudinal axis; and a final die for further reducing said outside diameter to a final outside diameter, said final die arranged between said welding means and said output end.
28. The in-line tube-forming apparatus of claim 27 further comprising a reduction die for reducing said initial diameter of said precursor tube to an intermediate diameter, wherein said reduction die is downstream of said plug-draw die and upstream of said welding means.
29. The in-line tube-forming apparatus of claim 28 further comprising a form box and a sink box, said form box comprising a first die holder and a second die holder, and said sink box comprising a third die holder, wherein said tube-forming die and said plug-draw die are mounted in said first die holder, said reduction die is mounted in said second die holder, and said final die is mounted in said third die holder.
30. The in-line tube-forming apparatus of claim 29, wherein said at least one welding means comprises a welding torch, a cyclomatic arc voltage control unit for said welding torch, and a welding power supply.
31. The tube-forming apparatus of claim 30, wherein said welding power supply pulses said an arc of welding torch at substantially 2000 times per second.
32. A method using an in-line tube-forming apparatus to form a final tube having a final outside diameter and a final wall thickness from a substantially flat strip of material having two longitudinal edges, said method comprising the steps of a) setting up said tube-forming apparatus for operation; b) forming a precursor tube with a tube-forming die; c) modifying said precursor tube with a plug draw die to move said strip longitudinal edges into an abutting relationship; d) welding said strip longitudinal edges together to form an initial tube having an initial outside diameter; and e) reducing with a sink die said initial outside diameter to said final outside diameter.
33. The method of claim 32, wherein said welding step further comprises generating a type of T weld along said abutted longitudinal edges.
34. The method of claim 32, wherein said setting up step further comprises a) threading said flat strip material through said tube-forming apparatus; and b) loading a plug into said precursor tube.
35. The method of claim 34, wherein said substantially flat strip of material further comprises a leading edge, and wherein said threading step further comprising the steps of a) trimming said leading edge to fit through a preform box; b) feeding said trimmed leading edge through a preform box; c) connecting a pull chain to said leading edge; d) pulling an additional length of said strip through said preform box; e) disconnecting said pull chain from said leading edge; f) pulling said additional length back out from said preform box; g) inserting said leading edge through said forming unit; and h) reattaching said pull chain to said leading edge.
36. A method of forming a tube from a substantially flat strip of material using an in-line process, said method comprising the step of placing a coil of flat strip material that has been rolled to a specific thickness and slit to a specific width on a payoff unit in a vertical orientation; preforming a section of tube; inserting a tube-forming die in a first die holder of a form box; insert a plug draw die in said first die holder of said form box; insert a reduction die in a second die holder of said form box; feeding preformed tube manually through dies in form box and through a weld box; dripping lubricant over the tube just prior to said tube forming die and said reduction die in said form box; insert a plug for said plug draw die into an inside of said preformed tube just prior to said first die holder; pushing said plug into said plug die; adjusting an electrode of a welding torch to a predetermined height above a top of said preformed tube; attaching a puller clamp and cable to lead end of said tube downstream of said sink box; ramping up tube puller to a predetermined tube line speed; applying power to said welding torch and ramping said power up to a predetermined amperage setting; establishing a desired weld integrity by adjusting said welding power and said tube line speed; and collecting tube on a collection spool of said tube puller.
37. A method employing an in-line tube-forming apparatus to form a tube from a substantially flat strip of material having two longitudinal edges, said method comprising the steps of a) setting up said tube-forming apparatus for operation; b) forming a precursor tube with a form box; c) cleaning said precursor tube with a cleaning station; d) welding said precursor tube into a tube in a weld box; and e) collecting said tube.
38. The method of claim 37 further comprising the steps of passing said tube through a sink die after said welding step and before said collecting step to refine an outside diameter of said tube.
Description  (OCR text may contain errors)

TUBE-FORMING MACHINE AND METHOD

CROSS-REFERENCE TO RELATED APPLICATION

This application is a nonprovisional, which claims priority to provisional application Serial No. 60/076,427, filed 24 February 1998, and to provisional application Serial No. 60/078,604, filed 18 March 1998. The '427 and '604 applications are hereby incorporated by reference as though fully set forth herein.

BACKGROUND OF THE INVENTION a. Field of the Invention

The instant invention is directed toward an apparatus and method of forming tubes and pertains generally to tube-forming devices. More specifically, it relates to machines and methods of automatically making tubes from flat stock material.

b. Background Art

It is well known in the art to form a tube of metallic material from a flat strip of material. Heretofore, however, the process has required the use of multiple sets of former rolls. A roll-form machine, for example, may use ten roll stands to initially shape the strip of metal into a generally tubular form. The material may be sent through three sets of pinch rolls in the weld box for welding the longitudinal edges of the strip to form a generally tubular shape. Subsequently, the material may be passed through a series of five roll stands to reduce and pull the welded tube through the forming and weld operations.

In addition to the prior art method of making tubes from flat strip material requiring the use of multiple sets of forming rolls, prior methods of welding the strip longitudinal edges together to form the initial tubular configuration have also left room for improvement. Namely, in the known method of shaping the flat strip into a generally tubular configuration, the longitudinal edges of the flat strip do not squarely abut. Rather, these edges, in the rolled configuration, before the longitudinal edges are welded together, meet in a V-shape. When the joint between the longitudinal edges is N-shaped, this requires a wedge weld to fill the V-shaped gap. This large R weld bead reduces tube integrity since the weld bead is metallurgically the weakest portion of the tube cross section.

SUMMARY OF THE INVENTION It is an object of the disclosed invention to provide an improved apparatus and method for forming tubular material from substantially flat strip material.

It is desirable, therefore, to be able to form a tube of material in a process involving a minimum number of forming operations to reduce the amount of time and material wasted transferring the preformed strip from one set of former rolls to a second, third, fourth, and in some cases fifth set for further processing. It is also desirable to weld the longitudinal edges of the substantially flat strip material while attempting to minimize the size of the weld bead.

The invention comprises an apparatus for forming a tube from a flat strip of material in a single operation. A payoff unit supplies the flat strip of material to a forming unit receiving. The forming unit creates the tube from the flat strip of material. Finally a tube puller is used to advance the material from the payoff unit and through the forming unit at a predetermined speed.

In another form, the invention comprises an in-line tube-forming apparatus that has an input end and an output end. A a substantially flat strip of material, having an initial strip width, an initial strip thickness, and a strip longitudinal axis, enters the input end and then moves forwardly through the apparatus from the input end to the output end. At the output end a final tube of the material, having a final outside diameter, a final wall thickness, and a tube longitudinal axis, exits.

The invention also comprises a method of using an in-line tube-forming apparatus to form a final tube having a final outside diameter and a final wall thickness from a substantially flat strip of material having two longitudinal edges. The method includes the steps of (a) setting up the tube-forming apparatus for operation; (b) forming a precursor tube with a tube-forming die; (c) modifying the precursor tube with a plug draw die to move the strip longitudinal edges into an abutting relationship; (d) welding the strip longitudinal edges together to form an initial tube having an initial outside diameter; and (e) reducing with a sink die the initial outside diameter to the final outside diameter.

In another form, the method of the present invention includes forming a tube from a substantially flat strip of material using an in-line process. The process includes the steps of placing a coil of flat strip material that has been rolled to a specific thickness and slit to a specific width on a payoff unit in a vertical orientation. Then a section of tube is preformed. Subsequently, a tube-forming die is inserted in a first die holder of a form box; a plug draw die is insert in the first die holder of the form box; and a reduction die is insert in a second die holder of the form box. Then, the preformed tube is feeding manually through the dies in the form box and through a weld box. A lubricant is dripped over the tube just prior to the tube forming die and the reduction die in the form box. A plug for the plug draw die is inserted into an inside of the preformed tube just prior to the first die holder, and the plug is pushed into the plug die. The next step required adjusting an electrode of a welding torch to a predetermined height above a top of the preformed tube. Then a puller clamp and cable are attached to lead end of the tube when it is downstream of the sink box. The tube puller is ramped up to a predetermined tube line speed, and power is applied to the welding torch and is ramped up to a predetermined amperage setting. A desired weld integrity is established by adjusting the welding power and the tube line speed. Finally, the tube is collected on a collection spool of the tube puller.

In yet another method of the present invention, an in-line tube-forming apparatus is used to form a tube from a substantially flat strip of material having two longitudinal edges. This method involves (a) setting up the tube-forming apparatus for operation; (b) forming a precursor tube with a form box; (c) cleaning the precursor tube with a cleaning station; (d) welding the precursor tube into a tube in a weld box; and (e) collecting the tube.

A more detailed explanation of the invention is provided in the following description and claims and is illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of the invention shown with a portion of the collection spool broken away;

Fig. 2 is a schematic top view of the forming unit and a portion of the collection spool, showing the path of the material through the tube-forming machine; Fig. 3 is a side view of the invention;

Fig. 4 is a side view in cross-section of the alignment or guide plates and the forming unit showing the dies comprising part of the forming unit;

Fig. 5 is a cross-sectional view along line 5-5 of Fig. 4, depicting the precursor tube before it enters a first tube-forming die of the preferred embodiment; Fig. 6 is a cross-sectional view along line 6-6 of Fig. 4, depicting the precursor tube at the nib of a first tube-forming die;

Fig. 7 is a cross-sectional view along line 7-7 of Fig. 4, depicting the precursor tube between the nib of the plug draw die and a floating plug;

Fig. 8 is a cross-sectional view along line 8-8 of Fig. 4, depicting the precursor tube at the nib of a reduction die;

Fig. 9 is a top view along line 9-9 of Fig. 3, depicting a cleaning station;

Fig. 10 is a cross-sectional side view taken along line 10-10 of Fig. 9, depicting the tube passing through a cleaning station;

Fig. 11 is a top view along line 11-11 of Fig. 3, depicting a wiping station; Fig. 12 is a cross-sectional side view along line 12-12 of Fig. 11, depicting passage of the tube through a wiping station;

Fig. 13 is a perspective view of the front, top, and right side of the weld box shown broken away from the remainder of the tube-forming machine;

Fig. 14 is a cross-sectional view of the weld box along line 14-14 of Fig. 13, showing the tip of the electrode riding above the tube as it passes through the weld box;

Fig. 15 is a partial cross-sectional view along line 15-15 of Fig. 14, depicting pinch blocks inside the weld box;

Fig. 16 is a partial cross-sectional view along line 16-16 of Fig. 14, depicting the pinch blocks pinching the tube together as it passes under the welding torch; Fig. 17 is a schematic cross-sectional view of the precursor tube as it would look just prior to the welding operation;

Fig. 18 is a schematic cross-sectional view of the tube, depicting the placement of the welding torch electrode directly above the tube seam to be welded; Fig. 19 is a schematic cross-sectional view of the tube after its longitudinal edges have been joined by the welding operation, showing the "T" type weld joint;

Fig. 20 is a partial cross-sectional view along line 20-20 of Fig. 2, depicting the cooling and fume-extraction system;

Fig. 21 is a partial cross-sectional view along line 21-21 of Fig. 2, depicting the air-pressure cooling tube;

Fig. 22 is a partial cross-sectional view along line 22-22 of Fig. 2, depicting a sink box;

Fig. 23 is a partial cross-sectional view along line 23-23 of Fig. 22, depicting the tube as it passes through the nib of the final die; Fig. 24 depicts a possible method of preparing the strip material for initial threading through the forming unit; and

Fig. 25 is a schematic representation of a portion of the weld box cooling system.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the preferred embodiment of the tube-forming apparatus 10 (Fig. 1) depicted in the accompanying drawings, a strip of substantially flat material 12 (Fig. 1) (e.g., stainless steel) is formed into a tube 14 (Fig. 1) having a desired diameter and desired wall thickness in a single, in-line process. As best shown in Figs. 1 and 3, flat strip material 12 is fed into an input end 16 of a forming unit 18, which can comprise a plurality of forming dies, plug draw dies, sink dies, and welders; and a tube 14 meeting the desired specifications is collected on a collection spool 20 as it leaves an output end 22 of the forming unit 18. Thus, it is possible to make tubing 14 meeting strict requirements at a rapid rate using a single in-line process that is capable of running continuously. Referring first to Figs. 1-3, the preferred embodiment of the invention will next be described. In the preferred embodiment a payoff unit 24 (Fig. 3) is rotatably mounted on a stand 26. On the payoff unit 24 is a vertically-oriented coil 28 of flat strip material 12. In the preferred embodiment, the coiled material 28 is freely fed into the forming unit 18 at a preferred processing rate. The preferred processing rate is a function of how quickly a tube puller 46 is capable of pulling the material through the forming unit 18. The speed at which the material may be processed is also a function of how quickly a welding torch 49 mounted above a weld box 38 can join the longitudinal edges 66, 68 (Fig. 5) of the strip material 12. As the strip material 12 exits the payoff unit 24, it first passes through a pair of alignment or guide plates 30.

It then enters a form box 32 mounted on a left-hand end of a table 56 comprising part of the forming unit 18. The details of the alignment plates 30 and the form box 32 will be described below. The form box 32 initially shapes the flat strip of material 12 into a precursor tube 13 (e.g., Fig. 4). That precursor tube 13 then passes through a series of cleaning 34 and wiping 36 stations before entering the weld box 38. The details of the cleaning and wiping stations 34, 36 and of the weld box 38 will be described below. The weld box 38 joins the longitudinal edges 66, 68 of the strip 12 to form a tube 14 from the precursor tube 13. After the weld box 38, the tube passes through a cooling and fume-extraction system 40 and an air-pressure cooling tube 42 before entering a sink box 44. In the sink box 44, the diameter of the tube 14 is reduced, resulting in the finished tube 14 to be collected. This finished tube 14 is collected on the collection spool 20 mounted on the tube puller 46, which provides the force that pulls the material through the forming unit 18.

Referring to Fig. 3, the payoff unit 24 of the preferred embodiment is next described. The payoff unit 24 comprises a base plate (not shown) with a vertical post or stand 26 attached to it. The upper end of the vertical post 26 has an axis 27 associated with it on which the coil 28 of strip material 12 is rotatably mounted.

Referring next to Figs. 4-8, details of the alignment plates 30 and the form box 32 mounted on the table 56 of the forming unit 18 are next described. Shown at the left-hand side of Fig. 4 are the alignment or guide plates 30. It is important to align the strip of material 12 as it passes through the machine 10 (Fig. 1). To ensure that the strip 12 enters the form box 32 in a precise, horizontal orientation, the alignment plates 30 are mounted adjacent the input end 16 of the forming unit 18 (Fig. 3). These alignment plates 30 vertically align the strip material 12 as it enters the form box 32. It is important, particularly for later forming and welding processes, that the strip material 12 entering the forming unit 18 is horizontally oriented and has a feed path that is vertically aligned with the form box 32 and weld box 38 comprising part of the forming unit 18 (Fig. 1). An adjustment screw 50 is operably associated with the alignment plates 30 to control the pressure that these plates 30 place on the strip material 12 and the vertical alignment of the path of the strip material 12 into the form box 32.

After the material 12 passes through the alignment plates 30, it enters the form box 32 where it is shaped into a precursor tube 13. The form box 32 is mounted to the table 56 of the forming unit 18 by bolts 52 (Fig. 4). In the preferred embodiment, the height of the form box 32 above the table 56 is controlled by machining at initial fabrication with precision machines holding tolerances to a millionth of an inch.

Alternatively, appropriate support blocks or shims 54 may be placed between the form box 32 and the table 56, but proper alignment is much more difficult to achieve in this manner. As the strip material 12 enters the form box 32, it passes through a first tube- forming die 58. Before the material 12 passes through this first tube-forming die 58, lubricant is dripped along path 60 onto the strip 12 from a first drip dispenser 62. In the preferred embodiment, the lubricant used is JO 8801, sold by Hangster fer, Ogoen Rd., Mantua, New Jersey 08051. Two other lubricants have been used successfully. These alternative lubricants are Motor Up and Gear Up, which are sold by Motor Up, P.O. Box 803377, Dallas, TX 75380, (732) 748-1323. These products have been discussed in various television infomercials. These alternative lubricants could be used individually or in combination. In the preferred embodiment, the lubricant is also dripped onto the strip material 12 from two additional first drip dispensers 63 and 160 (Fig. 22), as shown to best advantage in Fig. 3. Two of these three dispensers 62, 63 are clearly depicted in Fig. 4. Referring again to Fig. 4, the first tube-forming die 58 is mounted in a first die holder 64, which itself is mounted in the form box 32. A preferred material from which to make the nib of the first tube-forming die 58 (i.e., the portion of the die that actually has the hole in it including the angled surfaces that do the work) is synthetic or natural diamonds. The nib made from this diamond material may then be held in place inside a steel shell or case using powder as is normally done. All of the dies used in the preferred embodiment may be formed using these materials and techniques. As shown in Fig. 6, which is a cross-sectional view along line 6-6 of Fig. 4, as the strip material 12 passes through the nib of the first tube-forming die 58, the first and second longitudinal edges 66, 68, respectively, of the strip material 12 are brought toward each other. As shown in Fig. 5, which is a cross-sectional view along line 5-5 of Fig. 4, the strip material 12 begins to take on an arcuate shape in advance of entering the first tube-forming die 58 due to the influence of the first tube-forming die 58 on the strip material 12.

After passing through the first tube-forming die 58, the precursor tube 13 next passes through a plug draw die 70. The plug draw die helps form the strip 12 into a circular cross-section wherein the first and second longitudinal edges 66, 68 are as parallel as possible before the precursor tube 13 enters the weld box 38. This plug draw die 70 is also mounted in the first die holder 64. At the first plug draw die 70, the precursor tube 13 is worked between the plug draw die 70 itself and a floating plug 72 riding inside of the precursor tube 13. The interaction between the plug draw die 70 and the floating plug 72 brings the first and second longitudinal edges 66, 68 of the precursor tube 13 into contact (an abutting relationship), as best shown in Fig. 7, which is a partial cross-sectional view along line 7-7 of Fig. 4, and Fig. 17. As clearly visible in Fig. 7, formation of the precursor tube 13 is substantially complete as the precursor tube 13 passes through the nib of the plug draw die 70. The first and second longitudinal edges 66, 68 of the strip material 12 are forced together in this section of the forming unit 18 by slightly stretching the outside of the tube material in the plug draw die 70. The plug 72 helps stretch the outer surface of the precursor tube 13 slightly more than the inner surface of the precursor tube 13 so that the first and second longitudinal edges 66, 68 end up being almost precisely parallel when the precursor tube 13 later enters the weld box 38. Although plug draw die 70 may be used to reduce wall thickness, in the preferred embodiment of the present invention, the wall thickness of the tubing only reduces by about 1/10,000 of an inch as it passes through the plug draw die 70. The plug 72 is not used, therefore, specifically to reduce the wall thickness. Rather, the plug 72 permits the machine 10 to square up the first and second longitudinal edges 66, 68 of the strip 12 so that there is virtually no gap or V-shaped groove between these edges before the precursor tube 13 enters the weld block 38.

Continuing to refer to Fig. 4, as the precursor tube 13 exits the plug draw die 70, additional lubricant is dripped along path 65 onto the precursor tube 13 from a second drip dispenser 63 before the precursor tube 13 enters a reduction die 74 located near the right-hand side of the form box 32 as depicted in Fig. 4. The reduction die 74 is mounted in a second die holder 76, which itself is mounted in the form box 32. A small amount of the lubricant may reach the inside of the precursor tube 13 since the seam created by the first tube-forming die 58 and the plug draw die 70 is located on the top of the precursor tube 13, directly below the second drip dispenser 63. Due to the close proximity of the first and second longitudinal edges 66, 68, the amount of lubricant entering the interior of the precursor tube 13 at the second drip dispenser 63 is, however, minimal. In the reduction die 74, the precursor tube 13 enters the nib, and the diameter of the precursor tube 13 is thereby slightly reduced, as best shown in Fig. 8, which is a partial cross-sectional view along line 8-8 of Fig. 4. As best shown in Fig. 4, a channel 78 is formed through the form box 32 to permit lubricant from the second drip dispenser 63 to make its way to a pickup drain 80 located substantially below the first drip dispenser 62. The pickup drain 80 is part of a first lubricant circulation network 82, depicted in Fig. 3. As shown in Fig. 3, the pickup drain 80 routes the lubricant from the first and second drip dispensers 62, 63 into a first lubricant reservoir 84 via a first lubricant return line 86. When the first lubrication pump 88 is switched on, it draws the lubricant from the first lubricant reservoir 84 and circulates it under pressure back to the first and second drip dispensers 62, 63 via a first lubricant supply line 90. By monitoring the first lubricant reservoir 84, additional lubricant may be added if the supply of lubricant diminishes or becomes contaminated. The amount of lubricant reaching each of the first and second drip dispensers 62, 63 may be regulated by either the first lubricant pump 88 or valves 67 associated with each drip dispenser, or by a combination of these. The first lubricant return line 86 and the first lubricant supply line 90 may be made from, for example, PVC pipes.

Referring next to Figs. 1, 2, 3, 9, and 10, the cleaning stations 34 are described next. After the precursor tube 13 exits the form box 32 (Fig. 4), it enters a series of cleaning stations 34 (see, e.g., Figs. 1-3). In the preferred embodiment, there are two identical cleaning stations 34. Fig. 9 is a top view along line 9-9 of Fig. 3, depicting a cleaning station 34. As shown in Fig. 3, one or more solvent reservoirs 92 are mounted in a housing 94 such that the solvent may be gravitationally fed to a series of solvent drip dispensers 93. In the depicted embodiment, there are three solvent reservoirs 92 and each contains isopropyl alcohol. The isopropyl alcohol is gravitationally fed to two solvent drip dispensers 93 associated with each cleaning station 34. Each solvent drip dispenser 93, which may operate similar to an TV used in the medical profession, supplies the solvent to a drip tube 96. Each drip tube 96 is detachably associated with one of a plurality of drip ports 98. The plurality of drip ports 98 are arranged along a line that is substantially perpendicular to the direction of travel 100 of the tube 13 through the forming unit 18 (as best shown in Fig. 9). Referring now particularly to Figs. 9 and 10, the details of the cleaning stations 34 are described. Each cleaning station 34 comprises a mounting pad 102, which is slidably mounted between first and second guide bars 104, 106. These guide bars 104, 106 in turn are attached to the table 56 of the forming unit by bolts 107. Each mounting pad 102 may slide between the first and second guide bars 104, 106 in a direction indicated by arrow 108 of Fig. 9 and substantially perpendicular to the direction of travel 100 of the tube 13 through the forming unit 18. The ability to move the mounting pads 102 in this manner permits the relative path of the tube 13 through the cleaning station 34 to be changed during continuous operation of the tube- forming machine 10. Each cleaning station 34 also comprises a first plate 112 and a second plate 114. The first and second plates 112, 114 are removably attached to each other in overlapping configuration by four bolts 115. When the first and second plates 112, 114 are attached by the bolts 115, they are separated by cleaning pads 110 mounted to each plate 112, 114. The cleaning pads 110 are connected to each of the plates 112, 114 using a plurality of threaded pins 116 and nuts 118 to press a pinch strip 120 against the cleaning pads 110 to hold them to a respective plate 112, 114. For example, the first plate 112 is prepared for use by taking a cleaning pad 110, which is slightly longer than the first plate 112 and wrapping it around a longitudinal end of the plate 112 so that each end of the cleaning pad 110 may be pressed over four of the eight threaded pins 116 used in the preferred embodiment. With the cleaning pad 110 thus stretched over a surface of the plate 112 and held in position by being forced onto the eight threaded pins 116, the two pinch strips 120 are then placed over the threaded pins 116, and the nuts 118 are then threaded onto the threaded pins 116 and tightened against the pinch strips 120 to hold the cleaning pads 110 in position over the first plate 112. The cleaning pad 110 associated with the second plate 114 is mounted in a similar fashion.

Once the cleaning pads 110 are mounted onto the first and second plates 112, 114 as just described, the first and second plates 112, 114 are placed in overlapping configuration, and four bolts 115 are used to connect the first and second plates 112,

114 together. Clearly, more or fewer than four bolts 115 could be used, or a different method of attaching the first and second plates 112, 114 to one another could be used. Since the precursor tube 13 passes between the cleaning pads 110 mounted on the first and second plates 112, 114, the tension or pressure applied to the precursor tube 13 as it passes between the first and second plates 112, 114 may be controlled by the four attachment bolts 115. The first plate 112 differs from the second plate 114 in that the first plate 112 has the plurality of drip ports 98 formed therein.

Once the sandwich formed of the first plate 112, the second plate 114, and the respective cleaning pads 110 is formed, it is then attached to the mounting pad 102 by a pair of mounting bolts 123 (Fig. 10 shows one of these bolts). Each mounting bolt

123 passes through an upper plate 122 of the mounting pad 102 and threads into a plate 124 slidingly engaged in the underside of the second plate 114. The two mounting bolts 123 thus mount the sandwich comprising the first and second plates 112, 114 and their respective cleaning pads 110 to the mounting pad 102. Since the plate 124 is not fixedly mounted in the second plate 114, but rather is capable of sliding up and down vertically in the mounting hole cut in the second plate 122, the sandwich is capable of floating vertically up and down slightly. This vertical movement permits the sandwich to move slightly and thereby prevents the cleaning station 34 from putting unnecessary loads or pressure on the precursor tube 13 as it passes therethrough. Continuing to refer most particularly to Figs. 9 and 10, if the cleaning pads

110 become soiled, it is desirable and possible to move the mounting pad 102 and thereby the first and second plates 112, 114 in order to place a clean section of the cleaning pads 110 around the precursor tube 13 passing through the cleaning station 34. This step of moving the mounting pads 102 may be performed while the machine 10 is operating. To place fresh cleaning pads 110 over or around the precursor tube

13, the drip tubes 96 are removed from the particular drip port 98 to which they are attached. Then, the mounting pad 102 is moved along path 108 until a clean section of the pads 110 is placed over and around the precursor tube 13. In the preferred embodiment, this requires a movement of the mounting pads 102 of approximately 1/8 inch along line 108. Once the mounting pad 102 has been appropriately placed or positioned, the drip tubes 96 are then reattached to an alternate drip port 98 above the path 100 of travel of the precursor tube 13 through the cleaning station 34. Since the preferred solvent is isopropyl alcohol, and since the isopropyl alcohol is dripped slowly through the drip tubes 96 and drip ports 98, in the preferred embodiment it is unnecessary to have a capture or recovery system for the alcohol on the underside of the cleaning stations 34. The small amount of isopropyl alcohol dripped onto the cleaning pads 110 evaporates quickly and thus does not need to be collected.

The second cleaning station 34 of the preferred embodiment is the same as the first. As shown to best advantage in Fig. 2, the two cleaning stations 34 need not be positioned identically relative to the path 100 of travel of the precursor tube 13 through the forming unit 18. Further, it is unnecessary for the cleaning stations 34 to be moved or adjusted at the same temporal or distance intervals. This is particularly true since the first cleaning station 34 may become soiled more quickly than the second cleaning station 34 of the preferred embodiment. Thus, for example, the position of the first cleaning station 34 may require an adjustment frequency that is different from the adjustment frequency of the second cleaning station 34. After the precursor tube 13 passes through the two cleaning stations 34 of the preferred embodiment, it passes through a pair of wiping stations 36 (Figs. 1-3, 11, and 12). The wiping stations 36 wipe solvent, lubricant, and other contaminants from the exterior of the precursor tube 13. In the preferred embodiment, these wiping stations 36 are substantially identical. Fig. 11 is a top view along line 11-11 of Fig. 3, depicting one of the wiping stations 36. Fig. 12 is a partial cross-sectional view along line 12-12 of Fig. 11, showing the path 100 of the precursor tube 13 through the wiping station 36. These two wiping stations 36 are substantially similar to the cleaning stations 34 just described. They are, however, slightly smaller than the cleaning stations 34 in the preferred embodiment. As previously discussed in connection with the cleaning stations 34, a first cleaning pad 110' is attached to a first plate 112', and a second cleaning pad 110' is attached to a second plate 114' using threaded pins 116', pinch strips 120', and nuts 118'. The cleaning pads 110' of the wiping stations 36 are attached to their respective plates 112', 114' in the same manner as are the cleaning pads 110 in the cleaning stations 34. The first and second plates 112', 114' are then attached to each other in overlapping configuration using four bolts 115'. The only difference between the wiping stations 36 and the cleaning stations 34 in the preferred embodiment, other than the fact that the wiping stations 36 are slightly smaller than the cleaning stations 34, is the fact that the wiping stations 36 do not comprise drip ports 98 through the first or upper plate 112. Since no solvent is dripped onto the cleaning pads 110' at the wiping stations 36, the drip ports 98 used in connection with the cleaning stations 34 are unnecessary. lithe cleaning pads 110' associated with the wiping stations 36 become soiled, the mounting pads 102' on which the first and second plates 112', 114' are mounted may be moved in the direction of arrow 126 on Fig. 11 to place fresh cleaning pad

110' material over the precursor tube 13 passing through the respective wiping station 36. Again, in the preferred embodiment, the mounting pads 102' are moved approximately 1/8 inch to place fresh cleaning pad 110' material over the path 100 of the precursor tube 13 through the forming unit 18. The cleaning stations 34 and the wiping stations 36 thus have self-aligning features making them capable of aligning themselves both horizontally and vertically. As used herein, "vertically" means in a direction generally perpendicular to the top of the table 56 of the forming unit 18. The term "horizontally" refers to a direction generally parallel to the top of the table 56 of the forming unit 18. Referring to Figs. 9 and 11, horizontal adjustment involves movement along path 108 (Fig. 9) or path 126 (Fig. 11). Since the mounting pad 102 or 102' "floats" between the first and second guide rails 104, 106 (or 104', 106') for both the cleaning stations 34 and the wiping stations 36, the cleaning and wiping stations 34, 36 self-align to avoid putting excessive load on the precursor tube 13 perpendicular to its direction of travel 100 (i.e., perpendicular to its longitudinal axis). The cleaning stations 34 and wiping stations 36 are also capable of floating vertically about the mounting bolts 123, 123'

(see, e.g., Figs. 10 and 12). By permitting the cleaning stations 34 and wiping stations 36 to move or "float" both horizontally and vertically in this manner, the precursor tube 13 is less likely to bend or otherwise deform during operation of the tube- forming machine 10. After the precursor tube 13 exits the wiping stations 36, it next enters the weld box 38, clearly depicted in Figs. 1-3 and 13-16. Referring to these figures, several features of a preferred welding power supply 128 may be described. The weld box 38 has the welding torch 49 mounted above it, and a cyclomatic arc voltage control unit 129 for the welding torch 49 associated with it. In the preferred embodiment, the control unit 129 is like the Model 90A/4613A sold by PowCon Inc., 8123 Miralani

Drive, San Diego, California 92126, (619) 621-6300. The Model 90A is a control unit 129 used in combination with a 4613A probe. In the preferred embodiment, the welding power supply 128 causes the arc to pulse (i.e., cycles on and off) 2000 times per second. This high pulse rate stirs up the weld puddle, which improves penetration into the seam to assist in obtaining the "T" weld (Fig. 19) and results in a smooth weld bead. The welding power supply 128 for the welding torch 49 comprises various control knobs for adjusting, for example, the intensity of the welding torch 49 and the shape of the weld bead. A motor 129 is associated with the welding torch 49 for adjusting the position of the tip of the electrode 51 above the seam between the first and second longitudinal edges 66, 68 of the precursor tube 13. It is also possible to manually adjust the position of the tip of the electrode 51 above the seam using a control knob (not shown). Satisfactory tubing 14 has been made using a Tungsten inert gas (TIG) welder. The 4613 A probe of the preferred embodiment is a water- cooled unit, requiring cooling water hookups. The input 130 and output 132 tubes depicted in Fig. 13 provide the circulating cooling system for successful operation of the 4613A probe.

Also associated with the weld box 38 are two viewing windows: a front view window 133 and an angled end view window 135. The end view window 135 in the preferred embodiment provides a view of the orientation of the welding torch 49 relative to the tube 14 so that the position of the welding torch 49 above the tube 14 may be adjusted. Since this end view window 135 (Figs. 13 and 14) is angled, the tube 14 exiting the weld box 38 is not in the way as one looks through the end view window 135. The welding torch 49 itself is mounted to a bracket 137.

As shown to best advantage in Figs. 14 and 15, the weld box 38 comprises a cooling jacket having channels 139 therein to circulate a cooling fluid. The cooling jacket surrounds four of the six walls comprising the weld box 38. The cooling fluid circulating in this cooling jacket reduces the temperature of the weld box 38. The cooling fluid in the preferred embodiment is non-recirculating tap water, but any of numerous types of fluid and circulation systems could be used. For example, a closed circulation system could be used whereby the cooling fluid exiting the cooling jacket is itself cooled by a fan or a radiator before re-entering the cooling jacket. In the preferred embodiment, the cooling fluid never directly contacts the precursor tube 13 or tube 14 as it passes through the weld box 38. As best shown in Fig. 14, the cooling fluid enters the channels of the cooling jacket through an input line 130 (shown in phantom in Fig. 14 and shown schematically in Fig. 25) connected to the cooling jacket by an input port 131 near the bottom of the back side of the weld box 38. An air line 134 (shown schematically in Fig. 25) is associated with the cooling fluid input line 130 to mix a predetermined, desired amount of air with the cooling fluid to aid circulation and permit percolation of the cooling fluid within the cooling jacket. After being circulated through the cooling jacket of the weld box 38, the cooling fluid exits the cooling jacket through an output port near the top of the back side of the weld box

38. This output port is mounted on the back side of the weld box 38 in the preferred embodiment and connects to an output line 145 (shown schematically in Fig. 25). It is desirable that the air line 134, the input line 130, and the output line 145 associated with the cooling fluid each has an on/off valve (not shown) associated with it. By adjusting these valves, it is possible to regulate the temperature of the cooling fluid in the cooling jacket.

Referring more particularly to Figs. 14-16, the welding operation is described in more detail. Fig. 14 is a partial cross-sectional view along line 14-14 of Fig. 13 and shows the placement of the welding torch 49 relative to the tube 14. The 143 includes four probes 141 (two of which are clearly visible in Fig. 14) that are offset from each other at 90 and are adjacent to the tip of the welding torch 49. A donut 143 around the welding torch 49 contains a coil. This interaction between the coil and the probes 141, assists in stabilizing and controlling the welding arc. The position of the four probes 141 relative to the welding torch 49 and the path 100 of the tube 14 through the forming unit 18 is configured according to the instructions available from, for example, PowCon Inc. If the probes 141 are properly oriented relative to the welding torch 49 and the path of travel 100 of the tube 14 through the tube-forming machine 18, it is possible to more accurately control the shape and location of the generated weld bead.

As discussed above, after the precursor tube 13 passes through the form box 32 (Fig. 4), the first and second longitudinal edges 66, 68 of the strip 12 are oriented in substantially abutting configuration (see, e.g., Figs. 7 and 8). It remains, however, necessary to hold the first and second longitudinal edges 66, 68 against each other to obtain a weld of the desired integrity. This holding together of the first and second longitudinal edges 66, 68 is accomplished by a pair of pinch blocks 136 (or tube seam closure blocks), which are shown to best advantage in Figs. 15 and 16. In the preferred embodiment, the pinch blocks 136 are approximately 1/4 inch thick and 1 inch square and are made from bronze. A pinch pressure control knob 138 is threadedly attached to each of the pinch blocks 136. The details of the pinch pressure control knobs 138 are clearly visible in Figs. 13, 15, and 16. As shown in Fig. 15, an end of each pinch pressure control knob 138 protrudes from the weld box 38. One pinch pressure control knob 138 protrudes from the front surface of the weld box 38 as shown in Fig. 13, and the other pinch pressure control knob 138 (visible, for example, in Fig. 15) protrudes from the rear surface of the weld box 38.

Each pinch pressure control knob 138 is rotatably mounted to the weld box 38 so that rotation of each pinch pressure control knob 138 drives the pinch blocks 136 toward or away from each other along the paths 140 and 142 depicted in Fig. 16.

These paths 140, 142 are substantially perpendicular to the direction of travel 100 of the tube 14. Through appropriate adjustment of each pinch pressure control knob 138, a desired amount of pressure may be applied to the outside of the precursor tube 13 to hold the first and second longitudinal edges 66, 68 against each other before the welding step. It is also possible to adjust the position of the precursor tube 13 relative to the welding torch 49 by appropriate adjustment of the pinch pressure control knobs 138. It is particularly important that the seam between the first and second longitudinal edges 66, 68 be precisely on top of the precursor tube 13 as the unwelded precursor tube 13 enters the weld box 38 since the welding torch 49 is in a fixed position after initial setup of the machine 10 when the position of the welding torch

49 above the tube 14 is adjusted using the motor 129 or manual adjustment knob.

Referring next to Figs. 17-19, further details concerning the welding operation are discussed. Fig. 17 is a schematic cross-sectional view of the precursor tube 13 as it enters the weld box 38 As shown by Fig. 17, the first and second longitudinal edges 66, 68 of what was formerly a strip of material 12 fed into the forming unit 18 from the payoff unit 24 are oriented substantially parallel to each other as the precursor tube 13 enters the weld box 38. Fig. 18 is a schematic cross-sectional view of the precursor tube 13 in position below the welding torch 49. As shown in Figs. 16 and 18, the welding electrode 51 is positioned close to the precursor tube 13 for the welding operation. Fig. 19 is a schematic cross-sectional view of the tube 14 after the welding step. As shown in Fig. 19, the welding step completely joins the first and second longitudinal edges 66, 68 of the strip material 12, and the bead does not project substantially above the exterior or below the interior surfaces of the tube 14. Referring next to Figs. 1-3, and 20, the cooling and fume-extraction system 40 of the present invention is described next. As the tube 14 exits the weld box 38, it enters a substantially horizontal cooling tube 144 comprising part of the cooling and fume-extraction system 40. This horizontal cooling tube passes through a portion of a vertical tube 146 also comprising part of the cooling and fume-extraction system 40. One or more ports 147 permit gas flow from the horizontal cooling tube 144 to the vertical tube 146 of the cooling and fume-extraction system 40. Fresh compressed air is piped along path 148 into the vertical tube 146 through an air port 149 located above the horizontal cooling tube 144. The fresh compressed air is then forced upward along path 150 (Figs. 3 and 20). This fresh compressed air flow creates a low pressure region which draws the fumes 151 upward through the vertical tube 146 of the cooling and fume-extraction system 40. The mixed fresh air and fumes 151 may then be routed to the atmosphere or a filter system (not shown). This procedure allows the just- welded tube 14 to cool down without discoloration.

After passing through the cooling and fume-extraction system 40, the tube 14 next passes into an air-pressure cooling tube 42, best depicted in Figs. 1, 3 and 21. A vortex unit (not shown) operated by compressed air supplies very cold, pressurized air to an input line 152. This very cold air then follows path 154 through an input port

155 in the air-pressure cooling tube 42. The cold air entering through the input port 155 ultimately exits the air-pressure cooling tube 42 and vents to the atmosphere along paths 156 and 158. Such air-pressure cooling tubes 42 are known in the art. It is important to cool the tubing 14 as quickly as possible after the welding step. For example, if the tube 14 is formed from stainless steel, the more rapidly the stainless steel tube 14 is cooled after the welding step, the more ductile the tube remains. Since stainless steel can become brittle without the cooling step, this is an important aspect if the output from the tube-forming machine 10 of the present invention will be further processed in other machines. For example, if very fine needles are to be made from the stainless steel tubing 14 resulting from the operation of the tube-forming machine 10 of the present invention, the output tube 14 from the present invention must remain ductile so that it will be possible to further assist the tube sinking process.

Upon leaving the air-pressure cooling tube 42, the tube 14 next enters the sink box 44 (see, e.g., Figs. 1-3, 22, and 23) mounted on a shelf 157 of the tube puller 46.

Referring most particularly to Fig. 22, further details concerning the sink box 44 are now described. As the tube 14 enters the sink box 44, lubricant is dripped along path 159 onto the tube 14 from a third drip dispenser 160. As with the other drip dispensers 62, 63, the third drip dispenser 160 may have a valve 67 associated with it to regulate the amount of lubrication dripped onto the exterior surface of the tube 14 before it enters a final die 162 (sink die). The tube 14 is then pulled through the final die 162 mounted in a third die holder 164, which is in turn mounted in the sink box 44. As the tube 14 passes through the nib of the final die 162, the desired output diameter for the tube 14 is obtained, and any ridge or rough area resulting from the welding step is smoothed. In the preferred embodiment, the tube's wall thickness is left unchanged in the final die 162.

Fig. 22 also clearly depicts a second pickup drain 166 located in the bottom of the sink box 44 to collect lubricant from the third drip dispenser 160. This second pickup drain 166 comprises part of a second lubricant circulation network 168 depicted, for example, in Fig. 3. The second lubricant circulation network 168 comprises a second lubricant reservoir 170 connected to the second pickup drain 166 via a second lubricant return line 172. A second lubricant pump 174 pumps lubricant from the second lubricant reservoir 170 back to the third lubricant drip dispenser 160 via a second lubricant supply line 176. As discussed previously, the amount of lubricant delivered to any drip dispenser 62, 63, 160 may be controlled by operation of the lubricant pump 88 or 179 or valve 67 associated with the drip dispenser, or by a combination of the lubricant pump and the valve. Clearly, a single lubricant circulation network could supply lubricant to all of the lubricant drip dispensers if the same lubricant was used.

The vertical position of the sink box 44 is adjustable. A pair of support blocks or shims 54' (Fig. 22) are located below the sink box 44 between the sink box 44 and the shelf 157. By placing appropriately sized support blocks 54' between the sink box 44 and the shelf 157, a desired height of the sink box 44 above the shelf 157 may be achieved. Bolts 178 connect the sink box 44 to the shelf 157. Fig. 23 is a partial cross-sectional view along line 23-23 of Fig. 22. This figure depicts the cross- sectional shape of the tube 14 as it passes through the nib of the final die 162. As clearly shown in Fig. 23, at this station in the process, a fully formed tube 14 is present.

Since it can be difficult to properly align the precursor tube 13 relative to the form box 32, the cleaning stations 34, the wiping stations 36, the weld box 38, and the sink box 44, to facilitate the single in-line processing of the material from a flat strip

12 into a tube 14, the position of the sink box 44 may be adjustable using other known adjustment means that permit the position of the sink box 44 to be more precisely controlled. For example, the linear position and angular orientation of the sink box 44 relative to the path 100 of the tube through the tube-forming machine 10 may be adjustable. Through such adjustment of the linear position and angular orientation of the sink box 44 relative to the path 100 of the tube, it is possible to influence the path of the tube 14 through the entire tube-forming machine 10. This manipulation may be used, for example, to assist in properly aligning the path 100 of the tube 14 through the weld box 38. Such an orientation control system associated with the sink box 44 may also be used to put a slight bias in the tube 14 exiting the sink box 44 to facilitate coiling of the tube 14 onto the collection spool 20 and handling of the resulting coil of tubing 28 after it is removed from the collection spool 20. Off-the-shelf systems are available to manipulate the orientation of the sink box 44 in this manner.

In operation, the tube-forming machine 10 must first be threaded before it can begin continuous operation. In the preferred embodiment, the strip material 12 is prepared for threading by removing material from the leading edge of the strip 12 as shown in Fig. 24. For example, the strip 12 may be tapered by removing material from the first twelve to fifteen inches of the strip material 12 to form a blunt point 47. One could also prepare the leading edge of the strip 12 by manually bending the strip of material 12 into a tubular shape having a sufficiently small cross section to fit through a preform box 180 (Fig. 1). Once the leading portion of the strip 12 has been reduced in size, it is passed through the preform box 180 mounted next to the form box 32 on the table 56 of the forming unit 18 (see Fig. 1). This preform box 180 creates a tubular configuration from the strip material 12 similar to what is done by the form box 32 during actual operation. A clamp or attachment block connected to a pull chain or cable secured to the collection spool 20 of the tube puller 46 is attached to the leading edge of the strip 12. Subsequently, a motor (not shown) that drives the tube puller 46 is activated to rotate the collection spool 20 and thereby pull enough of the strip material 12 through the preform box 180 to reach the collecting spool 20 as shown by the dashed line in Fig. 1. Then, this preliminarily formed section of strip material 12 is manually pulled backward through the preform box 180 and fed forward through the operational path of the tube-forming machine 10. In other words, the section of pre-formed tube is backed out of the preform box 180 and fed through the form box 32, the cleaning stations 34, the wiping stations 36, the weld box 38, the cooling and fume-extraction system 40, the air-pressure cooling tube 42, and the sink box 44. This preliminarily formed section of tubing is then reconnected to the clamp or attachment block on the end of the pull chain or cable secured to the collection spool 20 of the tube puller 46. Clearly, the preliminarily formed section of tubing must be small enough to pass through all of the stations of the tube-forming machine, including the final die 162 located in the sink box 44. Thus, the preform box 180 must form the flat strip material 12 into a precursor tube 13 (Fig. 4) that is capable of passing through the entire tube-forming machine 10 so that it may be connected to the collection spool 20 as just described.

The remaining steps for setting up the machine for continuous operation include inserting the floating plug 72 (Fig. 4) of the plug draw die 70 located in the form box 32 into the interior of the precursor tube 13. This plug 72 is pushed forward into the plug draw die 70 using a small diameter rod if necessary. Once an appropriate section of strip material 12 has been threaded through the tube-forming machine 10, and the floating plug 72 is in place, the next step is to adjust the pinch blocks 136 in the weld box 38 (Figs. 15 and 16) to hold the tube seam closed for welding. The final step for setting up the machine for continuous operation is to adjust the welding torch electrode 51 to a predetermined height above the top of the tube 14, as best seen in Figs. 14, 16, and 18. The welding power supply 128 for the welding torch 49 coordinates the welding power with the tube processing line speed. The welding power is adjusted until a satisfactory "T" weld bead (see Fig. 19) is produced at the location where the first and second longitudinal edges 66, 68 of what used to be the flat strip 12 abut.

Once the tube-forming machine 10 has been fully set up, it can operate continuously until the material on the vertically oriented coil 28 of the payoff unit 24 is exhausted. During operation, the lubricant is continuously dripped over the tube 14 via the three drip dispensers 62, 63, 160. Thus, the material 12 is continuously lubricated before entering the various dies. A small amount of lubricant is also dripped by the first drip dispenser 62 onto the inside of the precursor tube 13 so that the floating plug 72 of the plug draw die 70 will slide against the inside of the precursor tube 13. The plug 72 keeps a substantial amount of the lubrication from passing downstream of the form box 32.

The collection spool 20 on the tube puller 46 may use one or more pins or rods parallel to and spaced radially from the axis of rotation of the collection spool 20 to facilitate easy removal of the formed and welded tubing 14 from the collection spool 20. Four such pins are used in the preferred embodiment. As the tube 14 exits the output end 22 of the forming unit 18, its path onto the collection spool 20 is controlled by the sink box 44. If the sink box 44 has a fixed position, the tube 14 comes off of the output end 22 of the forming unit 18 without changing paths. As the tube 14 is wound onto the collection spool 20, it is pushed toward the outside edge of the collection spool 20 by the new tube 14 being wound onto the collection spool 20.

As the material reaches the outside lip of the collection spool 20, it is then pushed off of this lip and collected on the four pins. In this manner, it is possible to easily remove the tubing 14 from the tube puller 46. Since the tube-forming machine 10 operates under tension, if the finished tubing 14 is simply collected on the collection spool 20 — like thread or yarn on a bobbin — it may be difficult, if not impossible, to remove the high tension tube 14 from the collection spool 20. If this system is used, the tube 14 itself facilitates its own removal from the collection spool 20 by driving the finished product outwardly on the collection spool 20 and onto the collection pins. If a system is used to manipulate the orientation of the sink box 44, as previously discussed, the path of the finished tubing 14 from the sink box 44 onto the collection spool 20 can be controlled. With the above-described tube-forming machine 10, it is possible to form a tube 14 that is 0.070 inches in diameter and having walls that are 0.004 inches thick from a strip of stainless steel that is 0.225 inches wide and 0.004 inches thick. The machine 10 described is not limited to this type of input strip size or output tube size, but this is a combination which has been successfully used in connection with this machine 10. The tubing 14 that is collected as the finished product of this machine 10 may become the raw product for a further process. During that further process, the tube 14 may, for example, have its wall thickness or its diameter reduced by drawing, such as plug drawing. Although a preferred embodiment of this invention has been described above, those skilled in the art could make numerous alterations to the disclosed embodiment without departing from the spirit or scope of this invention. For example, any number of form boxes or die boxes could be used to shape the material. There is no requirement that the apparatus be limited to the form box 32 and the sink box 44 used in the preferred embodiment. Also, more than one plug draw die could be used to obtain the shape where the first and second longitudinal edges 66, 68 of the strip 12 abut. It is also possible that more than one weld box 38 could be used. An important feature of this invention is that a single, in-line process is used to form a tube 14 of material from a flat strip 12. The machine is capable of operating continuously. All directional references (e.g., upper, lower, upward, downward, forward, backward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) above are only used for identification purposes to aid the reader's understanding of the present invention, and do not create limitations, particularly as to the position, orientation, or use of the invention. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting.

Patent Citations
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
CN102172663A *27 Jan 20117 Sep 2011江苏龙城洪力液压设备有限公司Production technology and equipment for composite steel tubes
EP1304176A2 *27 Sep 200223 Apr 2003NexansMethod for the continuous production of longitudinally seam welded metal tubes
EP1304176A3 *27 Sep 200230 Jun 2004NexansMethod for the continuous production of longitudinally seam welded metal tubes
EP1551591A1 *1 Jul 200213 Jul 2005McCrink, Edward J.Seam-welded air hardenable steel tubing
EP1551591A4 *1 Jul 200212 Mar 2008Edward J MccrinkSeam-welded air hardenable steel tubing
US754040210 Jan 20082 Jun 2009Kva, Inc.Method for controlling weld metal microstructure using localized controlled cooling of seam-welded joints
US761850317 Jan 200817 Nov 2009Mccrink Edward JMethod for improving the performance of seam-welded joints using post-weld heat treatment
Classifications
International ClassificationB21C37/08
Cooperative ClassificationB21C37/08
European ClassificationB21C37/08
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