US3789650A

US3789650A - Method for forming reduced diameter ends on elongated workpieces

Info

Publication number: US3789650A
Application number: US00275923A
Authority: US
Inventors: P Alexoff
Original assignee: Mitchell Co
Current assignee: Mitchell Co
Priority date: 1972-07-28
Filing date: 1972-07-28
Publication date: 1974-02-05
Anticipated expiration: 1991-02-05

Abstract

Method for forming reduced diameter ends on elongated workpieces, particularly tubing, characterized in that a tube is positioned between opposed dies aligned with the tube, one die being movable toward and away from a tube end while the other die is preferably fixed. Forcing the movable die against one end of the tube forces the other end into the fixed die and also forces the movable die over the first end, resulting in a reduction in diameter at both ends of the tube during a single power stroke of the movable die. Also described is a novel means for extracting a tube end from a reducing die after the die is forced over the tube end.

Description

eme

Feb. 5, 1974 METHOD FOR FORMING REDUCED DIAMETER ENDS ON ELONGATED WORKPIECES a Peter Alexoff, Poland, Ohio George A. Mitchell Company, Youngstown, Ohio July 28, 1972 [75] Inventor:

[73] Assignee:

US. Cl. 72/360, 72/377 Int. Cl 821d 41/04 Field of Search 72/345, 360, 377, 418

[ 56 References Cited UNITED STATES PATENTS 2,309,181 1/1943 Franck 72/360 Primary Examiner-Lowell A. Larson Attorney, Agent, or FirmThomas 1-1. Murray et a1.

[ ABSTRACT Method for forming reduced diameter ends on elongated workpieces, particularly tubing, characterized in that a tube is positioned between opposed dies aligned with the tube, one die being movable toward and away from a tube end while the other die is preferably fixed. Forcing the movable die against one end of the tube forces the other end into the fixed die and also forces the movable die over the first end, resulting in a reduction in diameter at both ends of the tube during a single power stroke of the movable die. Also described is a novel means for extracting a tube end from a reducing die after the die is forced over the tube end.

10 Claims, 14 Drawing Figures Pmmm w' 51914 meanest) sum 1 OF. A

PATENTED 51974 31 789,650

SHEU 30F Q FIG.

FIG. 45. 24 30 I2 36 FIG. 4F.

BACKGROUND OF THE INVENTION As is known, there are certain applications where an end of a relatively large diameter, heavy-walled steel tube must be reduced in diameter. For example, where a large steel tube of this type is to be drawn on a drawbench, its end must be reduced in diameter so that it can be passed through a drawing die and engaged by gripper jaws carried on a dolly or draw carriage which travels on a track on one side of the die. Another application is in the manufacture of vehicle axles which comprise tubular members having integral, reduced diameter ends to which are welded spindles for the wheels.

In the past, reduced diameter tube ends of this type have been formed by heating the end of the tube and subjecting it to a hammer swaging or upsetting operation. Both of these methods, however, require heating equipment for the tube ends and are relatively expensive. A tube swaging operation, for example,-is noisy and time consuming, and also requires high maintenance on the swaging machine. Furthermore, in the case of a vehicle axle or the like wherein both ends of the tube must be reduced in diameter, prior art swaging or upsetting equipment was capable of pointing only one end of a tube at a time. That is, one end of the tube had to be heated and then subjected to a hammer swaging or upsetting operation. Thereafter, the other end of the tube was heated and the hammer swaging or upsetting operation repeated.

SUMMARY OF THE INVENTION In accordance with the present invention, a new and improved method is provided for forming reduced diameter ends on elongated workpieces, particularly tubing, by forcing a die of cross-sectional area less than the original cross-sectional area of the workpiece over an unheated end of the workpiece to thereby reduce its diameter.

More specifically, the invention resides in the provision of a method for simultaneously reducing to a predetermined length the diameter of both ends of an unheated workpiece between fixed and movable dies by aligning the workpiece with the dies and thereafter forcing the movable die toward the workpiece such that the respective ends of the workpiece are forced 'into the fixed and movable dies, either by movement of the tube into a fixed die or movement over an end of the .tube by a movable die.

Further, in accordance with the invention, a method is provided for extracting a tube end from a die of the i type described above at the completion of a reducing operation. In this respect, ithas been found that when a die is forced over the cold end of-a tube to reduce its diameter, the forward end of the tube flares outwardly after the die has passed thereover. Consequently, when an attempt is made to remove the tube from the die, the flared end, which is larger in diameter than the die opening, tends to prevent its extraction from the die. In carrying out the invention, an elongated workpiece, usually a tube, is positioned between and coaxial with a pair of dies having facing, tapered die openings for receiving the respective ends of the workpiece. After the workpiece is thus positioned, at least one of the dies is moved toward the other until the opposite ends of the workpiece engage the tapered openings of the respective dies. At this point, sufficient pressure is applied to at least one of the dies to move it toward the other until both ends'of the workpiece are received within the respective dies with the ends of the workpiece reduced in diameter. Finally, one of the dies is then moved away from the other after the ends of the workpiece have been reduced in diameter to extract I the reduced diameter ends from the dies.

In the preferred embodiment of the invention shown herein,'one of the dies is fixed in position while the other is movable toward and away from it. In the usual case, the movable die will initially engage one end of a tube between the dies, and push it against the tapered opening in the other die. Continued movement of the movable die toward the fixed die under the force of a hydraulic cylinder, for example, will then push one end of the tube into the fixed die; whereupon the movable die passes over the other end. However, it makes little difference whether the movable die passes over the tube end before the other end is forced into the fixed die. In either case, the force exerted by the hydraulic cylinder on the movable die will eventually cause both dies to pass over the ends of the tube.

As was mentioned above, when a die is forced over the cold end of a tubular workpiece, the forward end of the reduced diameter end will flare outwardly. This is an inherent characteristic which results from pushing a die over a tube end. The flared end will prevent extraction of the workpiece from the die without the application of force thereto. In the present invention, and

assuming that reduced diameter ends are formed on both ends ofa workpiece, the problem of a flared end in the fixed die is eliminated by providing at the bottom of the fixed die a tapered orifice into which the flared 'end is forced during the reducing operation. In this manner, the flared end is reduced to the point where it can easily be extracted from the die.

A flared end is also formed on the reduced diameter end of the tube which the movable die is forced. While its flared end could also be eliminated by causing it to pass into a tapered die, the flared end is permitted to remain such that upon retraction of the movable die away from the fixed die, the end of the workpiece can easily move out of the fixed die by virtue of the fact that upon the retraction stroke, the flared end will engage the die opening in the movable die and pull the workpiece backwardly. Thereafter, a plunger within the movable die forces the workpiece out of the movable die opening such that it is discharged and assumes an exact and preset position on skids or the like regardless of the starting workpiece length.

This latter feature of a movable plunger to extract the flared end from the die can also be used in a pointing operation where, for example, a movable die is forced against an unclamped tube which abuts against a fixed stop at its end opposite the die. In both cases, the movable plunger acts to extract the tube end from the die in order that it can be transferred to a receiving station.

The above and other objects and features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification, and in which:

FIG. 1 is an elevational view of the tube end reducing apparatus of the invention as applied to equipment for forming reduced diameter ends on both ends ofa workpiece;

FIG. 2 is a cross-sectional view of the movable die and crosshead utilized in the apparatus of FIG. 1;

FIG. 3 is a cross-sectional view of the fixed die utilized in the apparatus of FIG. 1;

FIGS. 4A-4G schematically illustrate the sequence of operations utilized in the device of FIG. 1 for forming reduced diameter ends on both ends of a tube with a single power stroke;

FIGS. 5A-5C schematically illustrate the operation of apparatus for forming a reduced diameter portion or point on one end of a tube incorporating the movable plunger extraction apparatus of the invention; and

FIG. 6 is an illustration of the hydraulic system for the cylinder actuating means of the plunger apparatus of FIGS. SA-SC.

With reference now to the drawings, and particularly to FIG. 1, there is shown a pair of crossheads l0 and 12 interconnected by means of upper and lower slabs l4 and 16 which act, in essence, as tie rods between the two crossheads. The assembly is supported by means of a pair of platforms or

leg assemblies

18 and 20, substantially as shown. Adjacent the fixed crosshead at the left end of the machine as viewed in FIG. 1 is a stationary die assembly 22, hereinafter described in detail. At the right end of the apparatus is a movable die assembly 24 which can reciprocate back and forth along

guideways

26 and 28 provided on the

slabs

14 and 16, respectively. The die assembly 24 includes a movable crosshead 30 connected to the piston rods 32 and 34 (FIG. 4) of two

hydraulic cylinders

36 and 38, respectively. As will be appreciated, only one cylinder 38 is shown in FIG. 1. Between the

cylinders

36 and 38, and as again shown in FIG. 4, is a third, small diameter cylinder 40, the purpose of which will hereinafter be explained.

The workpiece whose ends are to be reduced as indicated by the reference numeral 42 in FIG. 1 rests on two sets of

roller devices

44 and 46. These preferably comprises balls carried within sockets and having protruding portions which engage the side wall of the workpiece; however any other suitable roller device can be employed. The devices 44 are fixed to the slab 16 adjacent the stationary die assembly 22; whereas the roller devices 46 are carried on a carriage 47 provided with rollers 50 which can move along guideways on the slab 16 such that the roller devices 46 will move inwardly or outwardly with the movable crosshead 30 and die assembly 24 as the

cylinders

36 and 38 are pressurized at one end or the other.

With reference now to FIG. 2, the movable die assembly 24 includes a block 48 provided with a die cavity 49 which receives the reducing die 52 itself as well as a pair of annular shims or

spacers

54 and 56. The

spacers

54 and 56 can be positioned either ahead of the die 52 as shown in FIG. 2 or behind it, thereby enabling the die to be shifted forwardly or backwardly to change the length of reduction as the end product dictates. The unit can compensate for a difference in starting lengths of approximately Z-Vz inches without effecting the length of reduction. Bolted to the block 48 is the crosshead 30. Between the crosshead 30 and the inner peripheral portion of the die 52 is an annular shim or spacer 60.

Reciprocable within the die 52 and the

spacers

54 and 56 is a plunger or rod 62 having an enlarged diameter end 64, the diameter D1 of the enlarged end 64 being slightly smaller than the diameter D2 of the die opening. The plunger 62 passes through an opening 66 in the crosshead 30 and is connected to the piston rod 68 of cylinder 40 (FIG. 4), this piston rod 68 projecting through an opening 70 in the stationary crosshead 12 to which the piston of cylinder 40 is connected. Suitable packings are provided between the piston rod 68 and the opening 70 as well as between the plunger 62 and the opening 66 in crosshead 30. Likewise, suitable packings 71 are provided between the block 48 and the

guideways

26 and 28 on slabs l4 and 16 on which it reciprocates.

With the arrangement shown, and assuming that the end of the tube enters the cavity formed by

annular spacers

54 and 56, it will engage the tapered surface 72 of the die 52. Furthermore, and assuming that the opposite end of the tube is fixed, continued movement of the die 52 under the force of

cylinders

36 and 38 will force the die over the end of the tube, thereby reducing its diameter to the diameter D2. During this time, and as will be explained hereinafter, the plunger 62 and its enlarged end 64 are retracted out of the die cavity to permit the tube to freely pass through the die. At the completion of the reducing operation, however, the plunger 62 acts to force the end ofthe reduced diameter end back out through the die opening.

With reference now to FIG. 3, the details of the stationary die assembly 22 are shown. It again includes a block 74 having a die opening 76 which receives the die 78 itself as well as a pair of

annular spacers

80 and 82 which serve the same purpose as

spacers

54 and 56 shown in FIG. 2. The length of reduction is restricted or governed by the distance of the die bearing or land to the positive abutment or the face of the plunger in its retracted position. Behind the block 74 is a second block 84 which abuts the crosshead 10 and is bolted thereto. Carried behind the die 78 in the block 74 is a tapered die element 86 which abuts against theblock 84. A plug 88 is carried in a recess provided in the block 84 and abuts against the edge of the tapered orifice 86 as shown.

With the arrangement described, and assuming that a tube is forced into the die cavity formed by elements 78-80, the end of the tube will initially engage tapered surface 90 and then by reduced inwardly to the diameter D2 of the die opening. Continued movement of the tube into the die will force the end of the reduced diameter portion of the tube against the tapered element 86. As was explained above, it is a characteristic of tubular elements passing through a die that the forward end of the reduced diameter portion will flare outwardly. That is, the outermost end of the tube will be of diameter greater than diameter D2. Under these circumstances, therefore, the tube cannot be readily withdrawn from the die cavity since the flared end will engage the die opening and prevent its removal. However, by virtue of the fact that the end of the tube is forced against the tapered element 86, the extreme end of the tube is forced radially inwardly, thereby eliminating the flare or bulge to enable the tube to be readily withdrawn from the die.

The sequence of operations in reducing the diameters of both ends of the tube with a single power stroke is shown in FIGS. 4A-4G. At the beginning of the cycle, the workpiece 42 is positioned on the

roller devices

44 and 46, not shown in FIGS. 4A-4G, such that it is axially aligned with the stationary and

movable die assemblies

22 and 24, respectively. At this time, it will be noted that the enlarged diameter end 64 of the plunger 62 is directly in the die opening of the movable die assembly 24.

In order to start a reducing operation, the

cylinders

36 and 38 are pressurized to force the crosshead 30 and the movable die assembly 24 to the left as viewed in FIG. 4B. In this process, the right end of the tube is engaged by the tapered surface 72 of the movable die assembly; and upon continued movement of die assembly 24, the tube is pushed to the left until its left end engages the tapered surface 90 of the stationary die assembly 22. The plunger 62 is held back by virtue of a constant pressure applied to the rod end of the center cylinder 40 urging the plunger backwardly. Continued force the left end of the tube through the die opening of thestationary die assembly 22 as shown in FIG. 48 until the extreme left end of the tube engages the tapered element 86 such that the flare or bulge produced on the end of the tube passing through the die is eliminated. Note that as the crosshead 30 and die assembly 24 move to the left as shown in FIG. 4B, the plunger 62 remains stationary until it abuts against the crosshead 30, whereupon it is forced to move to the left along with the die assembly 24 under the force of

cylinders

36 and 38.

Continued pressure on the crosshead 30 will force the movable die assembly 24 over the right end of the workpiece 42 as shown in FIG. 4C. That is, themovable die assembly 24 will move to the left until the extreme right end of the tube abuts against the enlarged diameter end 64 of the plunger 62, which is now retracted backwardly into abutment with crosshead 30. The extreme right end of the tube at this time is flared outwardly; however no provision is made for eliminating the flare at this time.

The next step in the process is shown in FIG. 4D wherein the opposite sides of the pistons in

cylinders

36 and 38 are pressurized to move the crosshead 30 and die assembly 24 backwardly. The die assembly 24 will move backwardly relative to the workpiece 42 until the die opening engages the right, flared end of the workpiece. At this point, continued backward movement of pressure on the crosshead 30 and die assembly 24 will the die assembly will pull the left end of the workpiece out of the stationary die assembly 22. The left end of the workpiece easily passes through the die opening of assembly 22 since the flare or bulge at the extreme left end of the tube has been removed by the tapered element 86 as explained above.

workpiece 42 is now extracted from fixed die assembly 22 and is essentially trapped between the flared reduced end and the forming die in movable head assembly 24.

Plunger 62 is larger in diameter than cylinder rod 68. Continued backward movement of crosshead 30 will cause plunger 62 to strike the inside face of fixed crosshead 12 causing the plunger to stop and create a fixed ram. Still further backward movement of crosshead 12 will force the enlarged plunger face 64 to pass through die assembly 24 and consequently force the reduced right hand flared end of workpiece 42 through the forming die in crosshead 24. It now remains to eject the right end of the workpiece from within the die opening of assembly 24. This is accomplished by pressurizing diameter end 64 to the left as viewed in FIG. 4F, thereby pushing the right end of the workpiece out of the movable die assembly 24 to a fixed point and into a position where it can be transferred sideways out of the apparatus as shown in FIG. 1. Thereafter, the plunger 62 and its enlarged diameter end 64 are retracted into their original positions as shown in FIG. 4G preparatory to a succeeding reducing operation.

With reference to FIGS, SA-SC, another embodiment of the invention is shown for producing a point on one end of a tube, such as that required for a subsequent drawing operation as explained above. In this case, the tube 94 abuts against a fixed stop 96. A movable crosshead 98 carrying a die 100 is adapted to be forced toward the right end of the tube as viewed in FIGS. 5A-5C by means of a pair of

hydraulic cylinders

102 and 104. A plug 106 extends through the die opening of die 100 and is provided with an enlarged diameter portion 108 which abuts against the backside of the die. Suitable means, not shown, are provided for holding the die 100 within the crosshead 98. The plug 106 is connected through a plunger, schematically illustrated at 110, to a hydraulic cylinder 112.

The control system for the hydraulic cylinder 112 is shown in FIG. 6. It comprises an air-over-oil system including a tank 114 connected through valve 116 to a suitable air supply 118. Oil 120 in the bottom of the tank 114 is adapted to flow through tubing 122 and check valve 124 to the right side of the cylinder 112. The fluid discharged from the right side of the cylinder 112, however, cannot flow back through the check valve 124 but must-rather flow through a throttling valve 126 which maintains a pressure greater than that required to strip the flared end through the die but less than the return capacity of the crosshead. With the arrangement shown, therefore, the plug 106 is continually urged into engagement with the die 100 or the end of the reduced diameter portion of the tube, as the case may be.

Reverting again to FIGS. 5A-5C, at the beginning of a pointing operation the tube 94 abuts against the fixed stop 96 and is aligned with the opening in die 100. Thereafter, the crosshead 98 is forced to the left as viewed in FIG. 5B, forcing the die over the right end of tube 94. This forms a point or reduced diameter end on the tube 94. The extreme right end of the point 95 is flared outwardly as at 97 in the manner described above, the flare being exaggerated in FIG. 5B for purposes of illustration. As the crosshead 98 and the die move to the left as viewed in FIG. 5B, the plug 106 will engage the forward end of the tube and remain stationary or possibly move back somewhat.

After the point 95 has thus been formed on the tube,

the

cylinders

102 and 104 are pressurized in the opposite sense to retract the crosshead 98 and the die 100. If it were'not for the plug 106, the flared end 97 would not pass through the opening of die 100. However, by virtue of the plug and the fact that a pressure of sufficient restraining capacity is exerted thereon by the hydraulic system shown in FIG. 6, it will maintain the tube 94 stationary as the die passes over the flared end so as to extract the tube as shown in FIG. 5C. The principle employed, of course, is the same as that utilized on the .movable die assembly in the embodiments of FIGS.

1-4, the plugs in the die acting to extract the tube end as the crosshead is retracted. I

Although the invention has been shown in connection with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention. 1 claim as my invention: 1. In the method for forming reduced diameter ends on an elongated cylindrical workpiece, the steps of:

positioning said workpiece between and coaxial with a pair of dies through which ends of the workpiece can pass, the dies having facing tapered die openings for receiving the respective ends of the workpiece, moving at least one of said dies toward the other die until the opposite ends of the workpiece engage the tapered openings of the respective dies,

thereafter forcing at least one of said dies toward the 7 other die until both ends of the workpiece have passed through the respective dies with the ends of the workpiece comprising cylindrical portions reduced in diameter with respect to the original diameter of the workpiece and having radiallyoutwardly flared ends, and

retracting said one die from the workpiece while exerting a force on said radially-outwardly flared end tending to move it through said one die in a direction opposite to the retracting movement of the die to extricate said end from the one die.

2. The method of claim 1 including the step of moving at least one of said dies away from the other after the ends of the workpiece have been reduced in diameter to extract said ends from the dies.

3. The method of claim 1 wherein said workpiece is positioned between the dies in an unclamped condition such that it can move toward one die under the force of the other die.

4. The method of claim 1 wherein one of said dies is fixed while the other is reciprocable toward and way from the fixed die.

5. In the method for forming reduced diameter ends on an elongated workpiece, the steps of:

positioning said workpiece between and coaxial with a pair of dies through which ends of the workpiece can pass, the dies having facing tapered die openings for receiving the respective ends of the workpiece, one of said dies being fixed and the other being reciprocable toward and away from said fixed die;

moving said reciprocable die toward the fixed die while pushing the workpiece toward the fixed die until the opposite ends of the workpiece are received within the respective die openings; continuing movement of the reciprocable die toward the fixed die while exerting sufficient pressure on the reciprocable die to force it over one end of the workpiece with the end of the workpiece projecting through the die while forcing the other end of the workpiece through the fixed die to form cylindrical portions on the ends of the workpiece which are reduced in diameter with respect to the original diameter of the workpiece, the ends of the workpiece being flared radially outwardly in passing through the dies, and

retracting the reciprocable die while exerting a force on the flared end of the workpiece in the reciprocable die in a direction opposite to the direction of retraction to extricate the end of the workpiece from said reciprocable die.

6. The method of claim 5 including the step of forcing the end of the workpiece entering the fixed die against a tapered surface to compensate for said flared end, whereby the end of the workpiece in the fixed die can be easily retracted therefrom upon movement of the movable die away from the fixed die which engages the flared end of the workpiece in said movable die.

7. The method of claim 6 including the step of forcing said flared end out of said movable die and after the opposite end of the workpiece has been removed from the fixed die upon retraction of the movable die.

8. The method of claim 7 including the step of forcing a plug into engagement with a reduced diameter end of the workpiece as the reciprocable die is forced thereover, and maintaining pressure on said plug tending to move it against the workpiece as said reciprocable die is retracted from the reduced diameter end whereby the plug will force the end of the tube through the die opening.

9. In the method of forming a reduced diameter end of an elongated workpiece, the steps of forcing a reciprocal die over said end of the workpiece such that the wrokpiece projects through the die and has a radiallyoutwardly flared end, the die having a diameter less than that of the original diameter of the workpiece, forcing a plug to move with the die under fluid pressure and into engagement with the reduced diameter end of the workpiece as said reciprocal die is forced thereover, providing a portion on said plug which will engage the die and limit movement of the plug through the die, exerting a force on said die to retract it from the end of the workpiece, and maintaining pressure on said plug tending to move it against the workpiece as said reciprocal die is retracted from the reduced diameter end whereby the plug will force the end of the tube through the die opening, the pressure maintained on said plug during the retraction of the die being sufficient to strip the die from the flared end of the workpiece but insufficient to prevent retraction of the die and plug when said portion of the plug engages the die during retraction.

10. Themethod of claim 9 including the step of initially aligning said workpiece with the die and causing said plug to move with the die as it approaches the end of the tube, the plug continually moving with the die until it engages the end of the workpiece passing through the die.

Claims

1. In the method for forming reduced diameter ends on an elongated cylindrical workpiece, the steps of: positioning said workpiece between and coaxial with a pair of dies through which ends of the workpiece can pass, the dies having facing tapered die openings for receiving the respective ends of the workpiece, moving at least one of said dies toward the other die until the opposite ends of the workpiece engage the tapered openings of the respective dies, thereafter forcing at least one of said dies toward the other die until both ends of the workpiece have passed through the respective dies with the ends of the workpiece comprising cylindrical portions reduced in diameter with respect to the original diameter of the workpiece and having radiallyoutwardly flared ends, and retracting said one die from the workpiece while exerting a force on said radially-outwardly flared end tending to move it through said one die in a direction opposite to the retracting movement of the die to extricate said end from the one die.

5. In the method for forming reduced diameter ends on an elongated workpiece, the steps of: positioning said workpiece between and coaxial with a pair of dies through which ends of the workpiece can pass, the dies having facing tapered die openings for receiving the respective ends of the workpiece, one of said dies being fixed and the other being reciprocable toward and away from said fixed die; moving said reciprocable die toward tHe fixed die while pushing the workpiece toward the fixed die until the opposite ends of the workpiece are received within the respective die openings; continuing movement of the reciprocable die toward the fixed die while exerting sufficient pressure on the reciprocable die to force it over one end of the workpiece with the end of the workpiece projecting through the die while forcing the other end of the workpiece through the fixed die to form cylindrical portions on the ends of the workpiece which are reduced in diameter with respect to the original diameter of the workpiece, the ends of the workpiece being flared radially outwardly in passing through the dies, and retracting the reciprocable die while exerting a force on the flared end of the workpiece in the reciprocable die in a direction opposite to the direction of retraction to extricate the end of the workpiece from said reciprocable die.

9. In the method of forming a reduced diameter end of an elongated workpiece, the steps of forcing a reciprocal die over said end of the workpiece such that the wrokpiece projects through the die and has a radially-outwardly flared end, the die having a diameter less than that of the original diameter of the workpiece, forcing a plug to move with the die under fluid pressure and into engagement with the reduced diameter end of the workpiece as said reciprocal die is forced thereover, providing a portion on said plug which will engage the die and limit movement of the plug through the die, exerting a force on said die to retract it from the end of the workpiece, and maintaining pressure on said plug tending to move it against the workpiece as said reciprocal die is retracted from the reduced diameter end whereby the plug will force the end of the tube through the die opening, the pressure maintained on said plug during the retraction of the die being sufficient to strip the die from the flared end of the workpiece but insufficient to prevent retraction of the die and plug when said portion of the plug engages the die during retraction.

10. The method of claim 9 including the step of initially aligning said workpiece with the die and causing said plug to move with the die as it approaches the end of the tube, the plug continually moving with the die until it engages the end of the workpiece passing through the die.