US3198926A

US3198926A - Method for upsetting elongated articles

Info

Publication number: US3198926A
Application number: US136662A
Authority: US
Inventors: Robert B Melmoth
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1961-09-07
Filing date: 1961-09-07
Publication date: 1965-08-03
Anticipated expiration: 1982-08-03
Also published as: GB934977A

Description

' g- 3, 1965 R. a MELMOTH 3,198,926

IETHOD FOR UPSBTTING BLONGATBD ARTICLES a s i 8 8 AIR PRESSURE ROBERT B. MELWTH INVENTUR.

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ATTORNEYS SCURCE R i r V/////////2/////////////////// Aug. 3, 1965 R. B. MELMOTH METHOD FOR UPSETTING ELONGATED ARTICLES Filed Sept. 7, 1961 3 Sheets-Sheet 2 ROBERT B. MELMOT H INVENTOR.

womDOw mmBQm ATTORNEYS Aug. 3, 1965 R. B. MELMOTH 3,198,925

METHOD FOR UPSETTING ELONGATED ARTICLES Filed Sept. '7, 1961 5 Sheets-Sheet 3 POWER SOURCE AIR PRESSURE SOURCE FIG. 3

ROBERT B. MEL MOTH INVENTOR.

ATTORNEYS United States Patent 3,1fi3fi26 METHGD FUR ELONGATED Robert B. Melmoth, Detroit, Mich, assiguor to Ford Motor Company, Dearhcrn, Mich a corporation of Delaware Filed Sept. 7, 1961, Ser. No. 136,662 4 Claims. (Cl. 2i9--75) This invention relates to a method of modifying the cross sectional area of an elongated article and more particularly to an improvement of a method of upsetting articles such as steel bars without the use of an enclosing die.

The conventional practice of upsetting steel bars comprises the steps of heating a portion of the bar to be upset to a forging temperature of 1,800 P, to 2,000" F. in a stationary heating chamber, and then feeding the heated portion into a die cavity. This is followed by the application of an axial force to the bar so that the heated por tion is enlarged until it fills out the die cavity.

An improvement of the conventional practice of upsetting a segment of an elongated article intermediate its ends is disclosed in a copending application Serial No. 134,236 filed on August 28, 1961.

This disclosed improvement of the conventional practice eliminates the use of an enclosing die by locally heating a first portion of the article with a heating means to render that portion substantially weaker structurally than the remainder of the article. The article is partially supported against radial displacement by a guide means before an axial thrust is applied to the article. Then a secend portion of the article is heated to render the second portion substantially weaker structurally than the remainder of the article. The guide means and the heating means are progressively moved with respect to the elongated article at a predetermined rate while the axial thrust is maintained on the article to upset the second portion so that the second portion forms a continuous upset mass with the first portion.

It has been found that this improved method of upsetting an elongated article without an enclosing die is a considerable improvement over the conventional prac- .tice, but it is still relatively time consuming, thereby preventing its application to mass production techniques.

The rate of relative movement of the guide means and heating means has to be accurately controlled at a relatively slow rate because the portions of the article have to be uniformly heated to a forging temperature throughout their entire mass to assure an upset segment of a uniform diameter. It has been found that a cold center in the heated portions may occur which will induce column failure and buckling of the upset segment of the article.

Also, the relative movement has to be relatively slow to permit the first portion to cool sufiiciently to prevent its further upset to a nonuniform diameter upon the application of the axial thrust to the article.

The method of this invention improves the method of upsetting the elongated article Without an enclosing die as disclosed in a copending application Serial No. 134,236 by impinging a cooling medium on the surface of the portion being heated and rotating the elongated article during the upsetting operation.

The impinging of a cooling medium on the surface of the article tends to promote uniformity of temperature from the exterior of the article to its interior. Also, the cooling medium engulfs the first portion adjacent to the second portion being heated, thereby increasing the rate of cooling of the previously upset portion by convection.

The rotation of the elongated article assures more uniform heating of the segment to be upset, which results in a more uniform diameter for the upset segment intermediate the ends of the elongated article.

An object of this invention is to provide an improved method for upsetting an elongated article without utilizing an enclosing die in a minimum time period.

A further object is to improve the method of upsetting elongated articles by maintaining concentricity of the upset portions of an elongated article.

A further object of this invention is to provide a method for locally upset-ting elongated articles in which the upset segment is of a uniform diameter.

Further objects and advantages of this invention will become more apparent as this description proceeds, particularly when considered in connection with the accompanying drawings in which:

FIGURE 1 is a schematic view partially in section of an apparatus depicting the first phase of the method of this invention;

FIGURE 2 is a schematic view partially in section of the same apparatus as seen in FIGURE 1 depicting the second phase of the method of this invention; and,

FIGURE 3 is a sectional view of a further embodiment of this invention which may be employed with the apparatus shown in FIGURES 1 and 2.

In FIGURE 1 can be seen a bar 1 1 which is to be upset by the improved method of this invention. The cross section of this bar 11 is usually circular, but it can be of any desired configuration. The bar 11 is supported against radial displacement by end support 1'2 secured to a base 1-3. A clamping means 14 grips the bar 11, thereby preventing its axial movement when an axial thrust is applied to the bar 11 by a rotatable chuck 15.

The clamping means 14 is mounted in a pillow block 16 attached to the base 1'3. Bearings 17 in the pillow block 16 permit the free rotation of the clamping means 14 with respect to the pillow block 16 but also prevent the axial movement of the clamping means 14 when an axial thrust is applied to the bar 11.

The rotatable chuck 1'5 firmly grips the end portion of the bar 11. This chuck may be mounted on a spindle of a drilling machine (not shown) so that it imparts rotation and an axial thrust to the bar 11 simultaneously. Any combined rotating and feed mechanism known in the art may be applied to provide rotational and axial forces to the bar 11.

Two guide rods 18 are disposed parallel to the bar 11 between the pillow block 16 and the end support 12. A spacer plate 19 attached to the guide rods 18 assures uniform spacing of the guide rods 18 between their end supports.

A guide means 20 is mounted coaxially with the bar 11 and is carried by the guide rods 13. The guide means 20 has a bushing 21 through which the bar 11 may be passed with sufiicient clearance to permit the axial movement of the guide means 29 relative to the bar 11. A cavity 22 in the guide means 20 houses an inductor 23 and a toroidal cooling means 24, both encircling the bar 11. The inductor 23, which may be water cooled if desired, is connected to a high frequency power source 25 of sufiicient capacity to heat a first portion 26 of the bar 11 encircled by the inductor 23 to a temperature ranging between 1,800 F. and 2,000 F. in a minimum time interval.

The toroidal cooling means 24 may be of an annular tubular configuration with jets 27 in the tubular wall to direct some of the cooling medium towards the surface of the first portion 26. Air, which has been found quite effective as a cooling medium in the application of the method of this invention, is conveyed through conduit 28 from an air pressure source 29 to the toroidal cooling means 24.

The guide means 20 has an integral link 30 which supports a threaded bushing 31. An externally threaded rod 32 which is supported by the base 13 is operatively connected to the bushing 31. Rotation of the threaded rod 32 moves the guide means along the guide rods 18 between the pillow block 16 and the end support 12. The threaded rod 32 can be rotated in either a clockwise or counterclockwise direction by a handle 33 or any other suitable means to impart movement to the guide means 20.

In FIGURE 2 is seen a cross sectional view of the same apparatus as seen in FIGURE 1 except that the first portion 26 of the bar 11 has already been upset and the inductor 23 and the toroidal cooling means 24 now encircle a second portion 34 of the same bar 11. The jets 27 are positioned in the toroidal cooling means 24 to direct the cooling medium to the surface of the second portion 34 being upset as well as to the surface of the first portion 26 previously upset. The guide means 20 and its associated inductor 23 and toroidal cooling means 24 have moved relative to the bar 11 in the direction of the arrow.

The rotatable chuck 15, which places an axial thrust on the bar 11, has displaced the end of the bar 11 axially in a direction opposite to the movement of the guide means 20. This is due to the upsetting of the first portion 26 of the bar which has reduced the length of the bar 11 accordingly.

in FIGURE 3 is seen an alternate embodiment of an inductor and toroidal cooling means which may be employed in the method of this invention.

In this embodiment, the inductor is a tubular copper coil 35 which is mounted in the cavity 22 of the guide means 20. This tubular coil 35 is connected to the high frequency power source to permit heating of a portion of the bar 11 by induction. The coil is also connected to the air pressure source 29. Jets 36 are placed in the internal diameter wall of the coil 35 at preselected positions to cause air or any other suitable cooling medium to impinge upon the surfaces of the bar 11. The utilization of an inductor as a quenching means is known in the state of the art as shown by U.S. Patent 2,170,130.

This embodiment has the advantage of combining the heating and cooling means in the cavity 22 of the guide means 20 to optimize the heating cycle during the upsetting operation. Another advantage of this embodiment lies in the prevention of overheating of the tubular coil 35 since the air passes through the interior of coil 35. Additional jets 3'7 may be placed in the end ring of the coil 35 to permit the directing of additional air to the surface of the portion of the bar 11 previously upset. The coil 35 may be of a double wall design to permit additional cooling of the coil 35 by water circulated between the walls.

A torsion bar spring for a motor vehicle front suspension system, for instance, calls for a .845 inch diameter spring steel bar (SAE5160) to have an upset segment of 1.062 inches diameter at its center over a length of 4 inches. The enlarged diameter has to be achieved Within a .031 inch tolerance.

In em loying the method of this invention utilizing the apparatus shown in FIGURE 1 to form the upset, the .845 inch diameter bar 11 is placed through the center opening provided in the clamping means 14, guide means 20, spacer plate 19, and the end support 12. Then the bar 11 is firmly gripped by the jaws of the clamping means 14 and by the jaws of the rotatable chuck 15.

The inductor 23 housed in the cavity 22 as seen in FIGURE 1 was machined from a 1 inch thick, 4 inch wide copper plate with an internal diameter of 1.25 inches. The inductor 23 in this instance was connected through a multiple ratio transformer to a 125 kw., 9,600 cycle motor generator. A 440 volt, 300 kva. capacitor was used in combination with the transformer.

The .845 inch diameter bar 11 was inductively heated to 1,800 F. in 6 seconds by applying a capacitance of 210 kva. to the inductor 23 through a 17:1 transformer ratio. An axial thrust of 4,000 pounds per square inch was applied to the end of the bar 11 by the rotatable chuck 15 which rotated the bar 11 at approximately revolutions per minute. Rotation of the threaded rod 32 moved the guide means 20 relative to the bar 11 at a rate of 1.53 inches per minute. The bushing 21 carried by the guide means 20 circumscribes the periphery of a segment of the bar 11 adjacent the portion being upset. This bushing 21 may provide partial support for the bar 11 at its most critical region as heat is conducted from the portion being upset to this adjacent segment which, thereby, may also be weakened structurally.

Air was supplied from the air pressure source 29 to the toroidal cooling means 24 at a pressure of 90 pounds per square inch.

Within 2 /2 minutes, a segment of the .845 inch diameter bar 11 was upset to the 1.060 inches diameter dimension with the segment being approximately 4 inches long. The upset segment obtained had a uniform diameter with a smooth tapering transition on each end of the upset segment.

By varying the temperature, the axial thrust, and the rate of relative movement between the bar 11 and the guide means 20, a segment of the steel bar 11 may be upset to any reasonable dimension over a predetermined distance by the method of this invention.

It is to be understood that the movement of the guide means 20 relative to the bar 11 can also be obtained if the guide means 20 remains fixed and the bar 11 is moved with respect to the guide means 20. The rate of relative movement may be controlled by manual or automatic means if so desired to permit the application of the method of this invention to the forming of upset segments on a repetitious basis.

I claim:

1. A method of upsetting an elongated metallic article in a plane perpendicular to its axis comprising the steps of rotating said elongated article, heating a first portion of said article to soften said first portion, securing the article on one side of said first portion against axial displacement, impinging a cooling fiuid upon the surface of said first portion, partially supporting said article against radial displacement only by guide means adjacent to said first portion, applying an axial thrust to said article from the other side of said first portion, heating a second portion of said article sufficiently to soften said second portion, impinging a cooling fluid upon the surface of said second portion, progressively moving said guide means away from said upset first portion with respect to said elongated article through successive portions at a predetermined rate while maintaining the axial thrust on and rotation of said article to upset said second portion so that said second portion forms a continuous mass with said first portion.

2. A method of upsetting a steel bar in a plane perpendicular to its axis comprising the steps of rotating said steel bar, heating a first portion of said steel bar to a temperature ranging between 1800 F. and 2000 F., securing the steel bar on one side of said first portion against axiel displacement, impinging a gaseous cooling fluid upon the surface of said first portion, partially supporting said steel bar against radial displacement only by guide means adjacent to said first portion, applying an axial thrust to the steel bar from the other side of said first portion to upset the latter, heating a second portion of said article to a temperature ranging between 1800 F. and 2000 F, impinging a gaseous cooling fluid upon the surface of said second portion, progressively and continuously moving said guide means away from said upset first portion with respect to said steel bar through succesive portions at a predetermined rate while maintaining the axial thrust on and rotation of said bar to upset said second portion so that said second portion forms a continuous upset mass with said first portion.

3. A method of upsetting a steel bar in a plane perendicular to its axis comprising the steps of rotating said steel bar, heating a first portion of said steel bar to a temperature ranging between 1800 F, and 2000 F. with an induction heating means, securing said steel bar on one side of said first portion against axial displacement, impinging a gaseous cooling fluid from a toroidal cooling means upon the surface of said first portion, partially supporting said steel bar against radial displacement only by guide means adjacent to said first portion, said induction heating means and toroidal cooling means carried by said guide means, applying an axial thrust to said steel bar from the other side of said first portion to upset the latter, heating a second portion of said steel bar to a temperature ranging between 1800 F. and 2000 F. with said induction heating means, impinging a gaseous cooling fluid from said toroidal cooling means upon the surfaces of said first and second portions, progressively and continuously moving said means away from said upset first portion with respect to said steel bar through successive portions at a predetermined rate while maintaining the axial thrust on and rotation of said steel bar to upset said second portion so that said second portion forms a continuous upset mass with said first portion.

4. A method of upsetting a steel bar in a plane perpendicular to its axis comprising the steps of rotating said steel bar, heating a first portion of said steel bar to a temperature ranging between 1800 F. and 2000 F. with an incluction heating coil, said induction heating coil having jets, securing the steel bar on one side of said first portion against axial displacement, passing a gaseous cooling fluid through the jets of said induction heating coil to cause said cooling fluid to impinge upon the surface of said first portion, partially supporting said steel bar against radial displacement only by guide means adjacent to said first portion, applying an axial thrust to said steel bar from the other side of said first portion, heating a second portion of said steel bar to a temperature ranging between 1800 F. and 2000 F. with said induction heating coil, passing a gaseous cooling fluid through the jets in said induction heating coil to cause the cooling fluid to impinge upon the surfaces of said first and second portions, progressively and continuously moving said guide means away from said upset first portion with respect to said steel bar through successive portions at a predetermined rate while maintaining the axial thrust on and rotation of said steel bar to upset said second portion so that said second portion forms a continuous upset mass with said first portion.

References Cited by the Examiner UNITED STATES PATENTS 1,945,092. 1/34 Storer. 2,405,478 8/46 Westin et a1. 2,473,245 6/49 Hanna. 2,495,060 1/50 Hanna 29552.4 X 2,780,000 2/57 Huet 29552.2 X

FOREIGN PATENTS 756,141 8/56 Great Britain.

WHITMORE A. WILTZ, Primary Examiner.

HYLAND BIZOT, Examiner.

Claims

1. A METHOD OF UPSETTING AN ELONGATED METALLIC ARTICLE IN A PLANE PERPENDICULAR TO ITS AXIS COMPRISING THE STEPS OF ROTATING SAID ELONGATED ARTICLE, HEATING A FIRST PORTION OF SAID ARTICLE TO SOFTEN SAID FIRST PORTION, SECURING THE ARTICLE ON ONE SIDE OF SAID FIRST PORTION AGAINST AXIAL DISPLACEMENT, IMPINGING A COOLING FLUID UPON THE SURFACE OF SAID FIRST PORTION, PARTIALLY SUPPORTING SAID ARTICLE AGAINST RADIAL DISPLACEMENT ONLY BY GUIDE MEANS ADJACENT TO SAID FIRST PORTION, APPLYING AN AXIAL THRUST TO SAID ARTICLE FROM THE OTHER SIDE OF SAID FIRST PORTION, HEATING A SECOND PORTION OF SAID ARTICLE SUFFICIENTLY TO SOFTEN SAID SECOND PORTION, IMPINGING A COOLING FLUID UPON THE SURFACE OF SAID SECOND PORTION, PROGRESSIVELY MOVING SAID GUIDE MEANS AWAY FROM SAID UPSET FIRST PORTION WITH RESPECT TO SAID ELONGATED ARTICLE THROUGH SUCCESSIVE PORTIONS AT A PREDETERMINED RATE WHILE MAINTAINING THE AXIAL THRUST ON AND ROTATION OF SAID ARTICLE TO UPSET SAID SECOND PORTION SO THAT SAID SECOND PORTION FORMS A CONTINUOUS MASS WITH SAID FIRST PORTION.