US3476911A - Process for electrically upsetting rod-shaped metal blanks,and die for carrying out the process - Google Patents

Description

NOV. 4, 1969 M NN 3,476,911

PROCESS FOR ELECTRICALLY UPSETTING ROD-SHAPED METAL BLANKS, AND DIE FOR CARRYING OUT THE PROCESS Filed Feb. 9, 1967 5 Sheets-Sheet 1 7 1 I2 .9 /guide electrode Fly 3 I I ram ram g l9 I -onvil elecrrode ll. i r;:# "7 "7- Fi I A A} l 1 l H t i J 10 i "I T lnven/ar:

HORST BACHMANN ATTORNEYS Nov. 4, 1969 Filed Feb. 9, '1967 H. BACHMANN 3,476,911

PROCESS FOR ELECTRICALLY UPSETTING ROD-SHAPED METAL BLANKS, AND DIE FOR CARRYING OUT THE PROCESS s Sheets-Sheet z In venfar HORST BACHMANN AT TORNE Y5 NOV. 4, 1969 BACHMANN 3,476,911

PROCESS FOR-ELECTRICALLY UPSETTING ROD-SHAPED METAL BLANKS, AND DIE FOR CARRYINGIOUT THE PROCESS Filed Feb 9, 196'? I 3 Sheets-Sheet 5 In van/or HORST BACHMANN M, ma

A T TORNEYS United States Patent 8 48 Int. Cl. Hb I/OO; B21d 37/16; G01k 1/14 U.S. Cl. 219-151 14 Claims ABSTRACT OF THE DISCLOSURE Electrically upsetting generally rod-shaped metal blanks in a die is done by a ram exerting the upsetting force, and a block carrying an anvil electrode and movable in the die in the direction of the upsetting force, to produce the counter-thrust required for upsetting. The die is movable in an outer sleeve. Initially, the die is held stationary within the sleeve while performing a predetermined partial stroke of the block in the direction of upset. Then the outer sleeve is moved co-directionally with the continuing movement of the block, as by mechanically locking the die to the block, after the latter has completed its predetermined partial stroke. The mechanical connection may include an abutment on the block and a counterstop aligned with the abutment for releasing the locking means.

The invention relates to a process for electrically upsetting generally rod-shaped metal blanks in a die by means of a ram exerting the upsetting pressure, and a block movable in the die in the direction of upset producing the counter-thrust required for upsetting.

Electrical upsetting makes it possible to produce trueto-size workpieces and is often superior to forging in the die because, in contrast to the latter method, there is no significant scaling or burning-up which prevent accurate measurements of the raw volume, particularly if intermediate heating is employed. Also, due to the abrasive efiect of these waste materials, forging tools are subject to rapid wear.

In electrical upsetting, the blanks are heated by electrical current flowing through them and upset in the same operation, mostly by means of hydraulic power. The method is suitable for rods of round, oval, prismatic or plane cross section. It is a particular advantage of the electrical upsetting method that any desired lengths of blank can be upset in a single uninterrupted operation. Even if the upset workpiece must be finally stamped in the die, the electrical upsetting method offers the advantage that the workpiece need not be reheated, and final stamping is carried out in the same heat.

As a result of the particular type of electrical resistance heating from within and the resulting high speed of heating, the workpiece remains substantially free of scale. Once proper adjustment has been made, eXcess heating or underheating is avoided. This eliminates burn-up or waste due to excessive or inappropriate heating. Thus, it becomes possible to so accurately limit the volume of upset that, after final stamping, workpieces are obtained which are extraordinarily true to size and require little or no additional machining. During the electrical upsetting, the rod-shaped blank is held by the clamping jaws of a guide electrode and firmly urged by the upsetting force acting on the free trailing end of the rod against an anvil electrode which in most cases is provided with a wearing plate. When the heating current is turned on, it heats the portion of the workpiece located between the Patented Nov. 4, 1969 tWo electrodes to forging temperature, and the workpiece is deformed by the force acting on the trailing end of the blank.

To produce workpieces with any desired length of upset; the anvil electrode is restracted into the die when the upsetting operation is performed in the die, or in the case of "free upsetting, the anvil electrode with its plate are retracted, thus affording more space for the upset head to thicken without reaching the buckling limit of the heated rod.

With conventional upsetting methods, workpieces can only be produced whose upset portion has the same diameter over its entire length. It is an object of the present invention to provide in simple manner a deformation method which permits the manufacture of a workpiece whose upset portion comprises segments of different diameters. In accordance with the invention, this problem is solved in that a die-sleeve moving in an outer die is at first held stationary with the die and, after the block has performed a predetermined partial stroke in the direction of upset, the sleeve is moved in the same direction as the" continuing movement of the block. After the block has, completed the predetermined partial stroke, the diesleeve is preferably automatically connected thereto. Since during the movement of the die-sleeve a segment of the outer die is exposed, a thicker segment of upset workpiece is formed corresponding to the larger inner diameter of the outer die. The outer die, which at first is covered, thus actually becomes effective as a die over its exposed part. A plurality of sleevelike dies may be mounted inside one another and released successively for movement with the block, if it is desired to produce a workpiece with multiple offsets.

The invention further relates to a die for carrying out the process. In accordance with the invention, the die is constructed so that at least one inner sleeve is disposed therein, the sleeve moving in the same direction as the block, after a latch locking it against the stationary outside die has been released. With such a die, the leading end of the workpiece in direction of upsetting is at first upset to a diameter corresponding to that of the inner sleeve. However, as soon as the lock of the inner sleeve which is movable in the direction of upset has been released and the sleeve can retreat together with the block, a larger free cross section obtains at the input end of the die and is filled with the oncoming upset material. The finished workpiece thus comprises a part of smaller diameter which has been upset first, and a connecting part of larger diameter, the length of the two parts depending on the length of upset obtaining when the locking of the inner sleeve is released.

The locking can be released at the appropriate moment automatically and simply by providing the block with an abutment which, after traversing a predetermined path, runs against and pushes out a counter-stop to release the lock. The counter-stop may project through a slot in the inner sleeve into the path of movement of the abutment connected to the block.

A cam secured to a rocking lever may also be used to serve as the counter-abutment, the rocking lever compris ing a locking notch abutting against a supporting surface of the inner sleeve. By suitably constructing the rocking lever, the speed ratio between the deflection of the counter-stop and the movement of the locking notch into unlatching position can be influenced so that unlatching occurs promptly, whereby greater accuracy of the length of the workpiece head is achieved.

In order to eliminate the necessity of the workpiece transmitting the power for moving the inner sleeve codirectionally with the block via the front wall of the sleeve, a contact surface is preferably provided in back of the counter-stop, seen in the direction of stroke, which is fixedly connected with the inner sleeve and onto which the abutment runs after deflection of the counter-stop. The block thereby automatically entrains the sleeve in the same direction, and undesired bulgelike obstructions of the material in the heating zone in front of the die inlet is avoided. If a head of small diameter is to be upset, followed by a segment of larger diameter, upsetting of the thinner head, because of the lesser upsetting ratio, requires a greater speed of deflection of the counter-stop than is the case when upsetting the thicker segment. Different workpiece segments must be upset with a variable pressure and/or heating current. A simple device for adjusting these operational values comprises a control member actuated by the counter-stop and controlling the speed of deviation, the upsetting pressure, and the heating current. In general, an electrical limit switch is used which triggers the required impulses.

In a logical application of the inventive concept, if workpieces are being produced which comprise a plurality of segments of diameters increasing in the direction of upset, more than one longitudinally movable inner sleeve may be provided. The sleeves, fitting into one another, are at first secured in their starting position against longitudinal movement and, when the segment which is in the process of being upset has reached the desired length, they are released successively for movement co-directionally with the block.

The invention is described hereinbelow in greater detail in connection with the drawings.

In the drawings:

FIG. 1 is a view in longitudinal section through a die embodying the principles of the invention.

FIG. 2 is a fragmentary view in section taken along the line 11-11 of FIG. 1.

FIG. 3 is a sectional diagram of the die of FIG. 1, during upsetting of the first segment of the workpiece...

FIG. 4 is a similar view of the device of FIG. 3 during upsetting of a second workpiece segment of larger diameter.

FIG. 5 is a view in longitudinal section of a modified embodiment of the invention.

FIG. 6 is a view in cross section of the device of FIG. 5 taken along the line VIVI in FIG. 5.

In FIG. 1, a die holder 1 is suitably mounted on the frame of a conventional electrical upsetting machine, not shown. A die 2 is secured in the holder 1 by means of a holding plate 3, the die 2 being exchangeable, as necessary, after release of screws 4. The holding plate 3 preferably has a tubular extension 5.

An inner sleeve 6, also acting as a die, is disposed in the die 2, and its leading end (reading in the direction of upset) is connected with an extension 7, as by means of a screw coupling 8. The entire inner sleeve 6 is thus exchangeable. At its input end, the sleeve 6 is provided with a wearing member 6a. Since wear is heaviest at the inlet end of the sleeve *6 which acts as a die, the wearing member 6a is also exchangeable, for example, by means of a screw connection. The sleeve 6 and the extension 7 are axially movable in the die 2 and its extension 5.

A block 9 equipped with a wearing plate 9a at its end facing the opening of the die moves in the interior of the sleeve 6. The block 9 and the wearing plate 9a form an anvil electrode.

At its end opposite the die opening, the block 9 is equipped with a piston 10 which is guided in a pressuremedium cylinder (not shown). Usually, the constant pressure of the pressure medium urges the piston 10 in the direction of the upsetting stroke, while the required counter-pressure is generated in the opposite cylinder chamber by an adjustable constant-pressure valve. The block 9 may thus be moved from the starting position shown in FIG. 1 to the left against a force generating the counterpressure needed for upsetting and, after termination of the upsetting process, the block 9 may be returned into its starting position, for example, by reversing the pressure-medium cylinder.

.4 An abutment 11 is secured to the block 9 and projects radially past the periphery of the block 9. The abutment 11 engages in an elongated slot 12 in the extension 7 of the sleeve 6. At the forward end of the elongated slot 12, seen in the direction of upset, a transverse slot 13 is provided in the extension 7, the slot 12 terminating in the slot 13. A latching cam 14, projects into the slot 13, its end disposed inside the slot having an inclined surface 15 onto which the abutment 11 runs as soon as the block 9 has moved to the left, during upsetting, by a length corresponding to that of the slot 12. As soon as the abutment 11 has forced the latching cam 14 outwardly against the action of a spring 16 which urges it inwardly, the cam 14 comes out of engagement with the holding surfaces formed laterally of the point of transition of the elongated slot 12 into the transverse slot 13. This releases the sleeve 6 from the position shown in FIG. 1, and it can also move to the left under the influence of the pressure transmitted by the workpiece. A larger cross-sectional area is thereby exposed at the input end of the die and is thereupon filled with the material of the workpiece.

The arrangement of the lock illustrated in the embodiment of FIG. 1 is shown in FIG. 2 on an enlarged scale and in partial cross section. It will be seen that the cam 14, which is movable radially of the die, is guided in a housing 17 connected with the extension 5 and closed by a cover 18. FIG. 2 also shows the holding surfaces with which the cam 14 secures the sleeve 6 against longitudinal displacement, so long as the lock has not been cleared. The latching surfaces are located between the lateral boundaries of the elongated slot 12 and the circumferential ends of the transverse slot 13.

The operation of the die in accordance with the invention is illustrated schematically in FIGS. 3 and 4. A rodshaped blank 19 is introduced into the die through the clamping jaws of a guide electrode 21 by means of a ram 20 which may be, for example, hydraulically actuated. The leading end of the blank 19 abuts on the anvil electrode or block 9 so that, when the current is turned on, it heats the part of the blank 19 between the forward end of the block 9 and the guide electrode 21. As the blank 19 is advanced by means of the ram 20 while the block 9 retreats, though at a lesser speed, a thickened upset portion 19a is formed.

As soon as the part 19a of the blank 19 has reached the desired length and the abutment 11 on the block 9 has cleared the lock 14 holding the sleeve 6, the sleeve 6 begins to move co-directionally with the block 9. The cross-sectional area at the input end of the die is thereby enlarged so that, as upsetting of the blank proceeds, a segment 19b (FIG. 4) is formed which has a larger diameter than the part 19a. The upsetting process is terminated when the part 19b has also attained the desired length. Since the part of the blank 19 located between the guide electrode 21 and the ram 20 is not heated, any desired lengths of rod-shaped blank 19 may be processed.

FIGS. 5 and 6 illustrate a modified embodiment of the arrangement of the die holder in the machine frame 22 in further detail. To avoid excessive heating and thereby premature wear of the die, the part most affected by the heat is cooled. Hollow spaces are provided for this purpose in the interior of a sheath surrounding the die holder 1A, for passing cooling fluid therethrough. The die holder 1A is equipped with cooling ribs at 1a. The cooling medium is supplied and discharged through pipe connections 1b and 1c.

The axially displaceable block 9 is provided with an exchangeable anvil electrode 9a at its end facing the workpiece.

As in the previously described embodiment, the twopart die comprises an outer sleeve-like member 2 and an inner sleeve 6. The inner sleeve 6 is secured as by threading 8 to a tubular extension 7. The sleeve 6 together with the extension 7 is secured in starting position against longitudinal displacement by a lock in the form of an angled rocking lever or toggle 23. As shown in FIG. 6, the toggle lever 23 is in the form of a transverse U, so that the part equipped with a locking notch 25 (FIG. 5) and directed against the direction of upset, engages in the elongated slot 12 in the extension 7 and abuts against a holding surface 7b formed at :the leading end of the slot 12.

The lever 23 is equipped in back of the locking notch 25, seen in direction of the working stroke, with a control cam 26 which also engages in the elongated slot 12. A double-cone thickening 11a on the block 9 forms an abutment which, after having completed a predetermined stroke, runs up the control cam 26 and presses the toggle lever 23 upwardly. The toggle lever 23 rotates about a pivot pin 24 disposed between supporting brackets 24a on the machine frame 22. As the abutment 11a swivels the toggle lever 23, the notch 25 comes out of contact with the holding surface 7b, so that the sleeve 6 participates in the longitudinal movement of the block 9. The sleeve 6 is automatically entrained at the same speed because, after dislocating the toggle lever 23, the abutment 11a abuts against a bearing surface 70. The bearing surface 7a is formed by a collet 70 at the trailing end of the tubular extension 7 and serves simultaneously for guiding the block 9 during the first part of the upsetting process.

An actuating pin 27 abuts against the upper side of the top arm of the toggle lever 23 and moves longitudinally in a screw plug 38, transversely to the direction of stroke of the block 9. Between the screw plug 38 and a head 27a at the lower end of the actuating pin 27, a spring 37 is provided which maintains the pin 27 in constant abutment against the toggle lever 23 and also takes care that the toggle lever 23 should properly engage in the elongated slot 12 when the die is in its starting position.

The upper end of the actuating pin 27 is provided with a conical point 29 which acts on an actuating member 30 when the pin is moved upwardly as the lever 23 is dislocated. The member 30 belongs to a limit switch 28 which, as shown in the drawing, is actuated when the abutment 11a swivels the toggle lever 23 from its starting position into releasing position and thereby releases the sleeve 6 for axial movement.

The limit switch 28 changes the speed of deviation of the block 9, for example, by displacing a pressure-medium cylinder actuating a constant-pressure valve on the block 9. Since during the first part of the upsetting process, the workpiece is upset to a smaller diameter than in the second part thereof, the block 9 must, because of the lesser upsetting ratio, have a greater speed of deviation (i.e., speed relative to the speed of the workpiece) during the first part of the process than during the second part thereof, because the larger diameter upset during the second part requires the feed of a larger amount of material per unit of time.

If desired, the limit switch 28 may also vary the heating current coming from the electrodes and/ or the upsetting pressure exerted by the ram 20. Increased heating current supply and/or pressure during upsetting of the workpiece segment of larger diameter may be necessary in order to carry out the process without lags even when working is done at a greater upsetting ratio.

Since the spring-loaded actuating pin 27 seeks to maintain the toggle lever 23 in engagement with the elongated slot 12, yet the toggle lever 23 must be swiveled into releasing position when the die is to be removed from its hold, for example after loosening the screws 4 in accordance with FIG. 5 in the direction toward the viewer, a device is provided which lifts the pin 27 against the action of the spring 37 and maintains it in raised position. The device comprises a manual lever 32 disposed in a bearisg 34 and swiveling about a horizontal axis. The end of the lever 32 facing the pin 27 is bifurcated, and in these forked ends, oblong holes 33 are provided which are substantially parallel with the pin 27. A transverse pin 31 secured to the pin 27 engages in said oblong holes 33. The oblong hole 33 is so shaped that, in the position of the lever 32 shown in FIG. 5, the pin 27 may move up and down for actuating the terminal switch 28. When the end of the lever 32 facing away from the pin 27 is depressed, it lifts the pin 27. To secure the lever 32 in this position, a latching device is provided. In the illustrated embodiment, it comprises a resiliently swiveling hook 36 which, when the right end of thgeslever 32 is depressed, is lowered over a projecting pin FIG. 5 shows the laterally twice-angled or stepped shape of the toggle lever 23. The locking notch 25 and the control cam 26 are mounted at the upper, horizontally extending arm of the lever 23, both standing above the elongated slot 12, or engaging therein during the first part of the upsetting process. Below the die, the pivot pin 24 is mounted between the support brackets 24a, the lever 23 swiveling about them when the abutment 11a impinges on the control cam 26.

The advantage of the releasable lock shown in FIGS. 5 and 6 as compared with the embodiment of FIGS. 1 and 2 is that no frictional resistance need be overcome when the toggle lever is swiveled, as is the case when displacing the locking cam 14 in accordance with FIGS. 1 and 2.

To those skilled in the art to which this invention relates, many changes in construction and widely difiering embodiments and applications of the inventions will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

I claim:

1. In an apparatus for upsetting metal rods and the like in a die by means of a ram exerting the upsetting force and anvil means movable in the die in the direction of the upsetting force and providing the counter-thrust required for upsetting the improvement comprising at least one inner sleeve disposed in said die and movable codirectionally with said anvil means, and holding means for locking said sleeve against said die during at least some portion of the movement of said anvil means.

2. The apparatus of claim 1 wherein said anvil means has an abutment, means defining a predetermined path for said abutment, and counter-stop means aligned with said abutment for releasing said holding means.

3. The apparatus of claim 2 wherein said inner sleeve has a slot, said counter-stop means projecting through said slot into the path of movement of said abutment.

4. The apparatus of claim 3 wherein said sleeve has a first elongated slot and a second slot following said first elongated slot when moving in the direction of upset, said abutment engaging in said first slot, a locking member in said second slot having a holding surface located at the transition of the elongated slot into said second slot, said holding surface being effective between said inner sleeve and said holding member.

5. The apparatus of claim 4 wherein said holding member comprises a spring and a cam displaceable transversely to the direction of movement of said inner sleeve against the action of said spring, said cam having an inclined surface rising against the direction of movement of said anvil means and projecting into the path of movement of said abutment.

6. The apparatus of claim 3 including a rocking lever, said counter-stop comprising a cam secured to said rocking lever, said rocking lever having a locking notch abutting against a holding surface of said inner sleeve.

7. The apparatus of claim 6 including a bearing surface in back of said counter-stop and fixedly connected to said sleeve, said abutment engaging said bearing surface after said counter-stop has been deflected.

8. The apparatus of claim 7, including a switch member actuated by said counter-stop for controlling any of the speed of deflection of said anvil means, the upsetting pressure, and the heating current.

9. In an apparatus for electrically upsetting generally rod-shaped metal blanks in a stationary outside die by means of a ram exerting the upsetting force and a block movable in the die in the direction of the upsetting force which produces the counter-thrust required for upsetting and means for electrically heating the blank being upset, the improvement comprising: at least one inner sleeve disposed in said die and movable co-directionally with said block, and means for locking said sleeve against said stationary outside die during at least some movement of said block.

10. The apparatus as described in claim 9 including an abutment on said block; means forming a predetermined path for said abutment; and a counter-stop aligned with said abutment for releasing the locking means, said counter-stop projecting through a slot in said inner sleeve into the path of movement of said abutment.

11. A method for upsetting metal rods and the like in a die by means of a ram exerting the upsetting force, and a block movable in the die in the direction of the upsetting force to produce the counter-thrust required for upsetting said die moving in an outer sleeve, comprising the steps of:

initially holding the die stationary within said sleeve while performing a predetermined partial stroke of the block in the direction of upset, and

then moving said outer sleeve co-directionally with the continuing movement of the block.

12. The method of claim 11 including the step of mechanically connecting the die to the block after the latter has completed the predetermined partial stroke.

13. A method for electrically upsetting generally rodshaped metal blanks in a die by means of a ram exerting the upsetting force, and a block movable in the die in the direction of the upsetting force which produces the counter-thrust required for upsetting, comprising the Steps of:

providing an outer sleeve within which said die can move;

electrically heating the end of each metal blank;

initially holding the die stationary within said sleeve While performing a predetermined partial stroke of the block in the direction of upset, and

moving said outer sleeve co-directionally With the continuing movement of the block.

14. The method as described in claim 13 including the step of mechanically connecting the die to the block after the latter has completed the predetermined partial stroke.

References Cited UNITED STATES PATENTS 2,581,774 l/1952 Stone et al. 219-151 2,621,344 12/1952 Friedman 72-354 X 3,283,556 11/1966 Putetti et a1. 72354 X 3,347,081 10/1967 Bachmann 72-342 FOREIGN PATENTS 475,573 4/1929' Germany. 863,588 1/1953 Germany. 26,150 11/1963 Germany.

JOSEPH V. TRUHE, Primary Examiner B. A. STEIN, Assistant Examiner US. Cl. X.R.

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