US2195775A - Electric forging and apparatus therefor - Google Patents

Description

April 2, 1940. E. GASPAR ELECTRIC FQRGING AND APPARATUS THEREFOR Filed June 30, 1939 3 Sheets-Sheet 1 4w X QQ hi; m w 1% WI P I I: III w 1 a I h mmxmawfi R Q fimwfi RN w 3 April 2, 1940. E. GASPAR ELECTRIC FORGING AND APPARATUS THEREFOR Filed June 30, 1939 3 Sheets-Sheet 2 Ap" 2, 1940. E. GASPAR ELECTRIC FORGING AND APPARATUS THEREFOR Filed June 30, 1939 3 Sheets-$heet 5 g www ANN wmw @w 5. @w ENE Qmw Qww & $1 I fi v k I I I I 1 1 Y 1% Q% Patented Apr. 2, 1940 EIECTRIC FOBGING AND APPARATUS Emeric Gaspar, London, England,

, London, England, a British Omes Limited company a-ignor to Application Jane 30, 1939, Serial No. 283,244 In Great Britain April :1, 1938 This application corresponds to the application of Gaspar and Omes Limited, Serial No. 12,637/1938 which was filed in Great Britain on April 27, 1938.

This invention comprises improvements in or relating to electric forging and apparatus therefor. It has previously been proposed to forge rods to a point by electrically heating while under tension so that as soon as the material becomes softened it is drawn out until it breaks.

It has been found, however, that in some cases in tension forging the structure of the steel may be damaged by overheating and burning, and also that the points produced are not always identical in shape with one another. For

some purposes, such for example as the manufacture of projectiles, the points produced are too rounded and with some steels the points may break of! flat after reduction of the section has proceeded to a certain degree. Again, steel should not be deformed unless it is hot enough, otherwise the structure of the metal will be damaged. With the previously existing apparatus however in which the tension was applied at the same time as the initiation of the heating current, or otherwise controlled solely at the will of the operator, it was probable that deformation would be started before the proper forging temperature was reached, 'It is an object of the present invention to improve the process in these According to the present invention a process of electric forging under tension is characterised by the fact that the tension is applied only after a the piece to be forged has reached a predetermined forging heat and that the heating current is cut oil, or at least reduced, prior to the application of the deformation under tension. It is found that in this way the forging operation can be caused to take place within the limits of forging temperature of the steel under treatment and satisfactory tapered shapes can be produced, including particularly shapes corresponding to the pointed ends of projectiles. I

45 The application of tension to a workpiece may be initiated automatically by a heat-responsive element in the neighbourhood of or in contact with the heated portion of the workpiece. Again, the reduction or cutting-oft of the heating current 50 may be controlled, so as to occur automatically, by a heat-sensitive device in the neighbourhood of or in contact with the heated portion of the workpiece.

The invention further comprises an electric u forging apparatus comprising in combination two work-holding vices for gripping the workpiece at separated points along its length, means for supplying electric current to the workpiece through the work-holding vices to heat it, means for moving the vices apart so asto app y tension to the 5 workpiece and a device for simultaneously cutting of! or reducing the heating current and initiating the operation of the means for moving the vices apart.

The heat-responsive element above referred 10 to may consist of an electric eye" which is electrically connected to a relay, operation of which cuts off or reduces the heating current and initiates the forging movement. The tension for forging may be applied by means of an hydraulic 15 ram operatively connected to one of the vices and under the control of an hydraulic valve which is magnet-actuated, the magnet being controlled by the heat-responsive element.

In some instances instead of, or in addition to 2 applying tension to the workpieces the forging of the point can be effected by swaging tools which are applied at a time (corresponding to that of the application of the tension to the workpiece above described) after the workpiece 5 has been brought to the desired heat and the forging operation is (as before) so conducted that the current is diminished or cut off before the reduction of the cross-section of the workpiece has proceeded too far. 30

The following is a description by way of example of one form of apparatus in accordance with the invention and of the process of the invention as carried out therein.

In the accompanying drawings- 5 Figure 1 is a side elevation and Figure 2 a plan of a forging machine;

Figure 3 is a diagrammatic representation of the working parts and of the electrical and hydraulic connections; 40

Figure 4 is a diagrammatic plan of an alternative construction,

Figure 5 shows the pointed structure produced, Figure 6 is a vertical sectional view taken substantially on the line 6-6 of Figure 4.

Referring to Figures 1 and 2.the forging machine comprises a bed plate il having longitudinal guideways I! supported on a framework i3 within which are located, behind louvred cover plates H, the electrical step-down transformer for supplying heating current and an electrically driven pump for hydraulic powerfi These latter parts are not illustrated in detail as they are common practice in forging machines.

Upon the longitudinal guideways ii there are mounted two work-holding vices I, I! which are capable of movement along the guideways. The vice I1 is insulated from the lathe bed and the two vices are connected to the terminals of the step-down transformer above referred to so that when a workpiece II is gripped so that it extends between the vices, the portion of the workpiece which spans the interval between them becomes heated to forging temperature.

Each of the vices comprises a body portion which supports a lower vice jaw I! and an hydraulic cylinder 28 containing a ram 2i which is connected to an upper movable vice jaw 22.

The vice jaws is, I! are made removable from the portions of the vice which hold them and they are interchangeable with other vice jaws, the various vice jaws being shaped, where they meet together, so as to grip various desired shapes of workpieces. The jaw members ll, 22 are aligned with one another in a direction parallel with the guideways of the bed plate so that the workpiece ll, when gripped, is parallel with the guideways. The vices I 4, ii are made of bronze or some other good electrical conductor. The vice i! is adjustably secured on the guideways by means of side rods 23 which are insulated from the vice and are connected to a crosshead 24 operated by a screw 25. The screw 25 passes through a screwed nut 28 which is journalled in a transverse bracket 21 at the end of the machine bed. The nut 26 carries at one end wormwheel teeth 28 which mesh with a worm 29 mounted on a shaft Ill. The shaft 30 carries a sprocket 3! which is rotated by means of a chain 32 from a handwheel N and thus the vice I! can be set, by rotation of the handwheel, at any desired position along the bed.

The other vice i8 is connected by rods 34 to a crosshead 35 which is made capable of sliding along the guideways i2 and is secured on the end of a ram 36 working in an hydraulic cylinder 31. The cylinder is bolted by flanges 34 to the bed plate ii. The hydraulic cylinder 31 is made double-acting so that it caniorce the vice iS'to move in either direction. The vices i6, i1

are given suiiicient gripping force upon the workpiece to enable them to prevent the workpiece from sliding through the jaws under the tension required for forging. Any other additional means for gripping the ends of the workpieces and preventing them from sliding through the vice jaws may be provided if this is found desirable or necessary.

Between the vices and arranged in a position so that it points toward the central portion of the workpiece i8 where it spans the interval from vice to vice there is a photo-electric cell 40 which is sensitive to the rise of temperature brought about in the workpiece by the heating current. Such a photo-electric cell is sometimes known as an electric eye." The cell 40 is so positioned and adjusted that upon the workpiece reaching the desired forging temperature it will actuate a relay 4| (Figure 3). The relay is energised by a supply circuit 42. The combination of electric eye and relay is well-known in itself and therefore the construction of these parts is not indicated in detail in the drawing. The relay 4!, when actuated, serves to break a circuit 43, 44, 45 which normally supplies with current a magnet 48 of a clapper switch 41. The switch 41 controls the circuit of the primary winding 48 of the step-down transformer before referred to which is shown at 49 in Figure 3 and has a secondary winding 50. The circuit of the primary winding 44 is energised from a power supply I. When the relay It operates to break the circuit 43, 44, 45 the clapper switch magnet 44 is deenergised and the clapper switch opens, thus cutting oi! the supply of power to the transformer 4| and thereby cutting of! the heating current from the workpiece II.

The relay 4! at the same time energises a control solenoid I! through the circuit ill, I44. The control solenoid I2 is connected by a rod ll to a control lever II which projects from a valve box II. This lever and the valve box can also be seen in the plan, Figure 2. The object of the energisation of the solenoid i2 is to cause the ram 84 to be retracted and apply tension to the workpiece in order to draw it into a pointed shape between the vices I, ii. For this purpose the valve box II is supplied with oil under pressure from a pump is through a supply pipe 81. It is not necessary to describe in detail the construction of the valves but is suiiicient for the present purpose to explain that on depression of the lever 84, either by hand or by the action of the solenoid 82, the oil pressure is directed into the pipe II which leads through a throttle valve 59 to the front end of the hydraulic cylinder 31. At the same time the pipe 6!, which is in communication with the back end of the cylinder through a throttle valve I, is connected by the action of the lever '4 in the valve box 55 with an exhaust pipe 62 leading to an oil return sump 63 from which the pump 56 draws its supply of oil. On the other hand, if the lever 54 is raised, the pipe 54 is connected to the exhaust pipe 62 and the pipe I to the oil pressure supply, thereby reversing the movement of the ram 36 and causing it to advance. The lever 54 is urged upwardly by a spring 64 and the latch 65 is capable of holding it down. The latch 65 is connected to a sliding rod 46 mounted at the side of the machine bed ll so as to extend parallel to the ram 36. The rod 68 is urged by a spring 61 in such a direction as to cause the latch to tend to slip over the lever 54 and hold it down as soon as it is depressed. Upon the rod 66 is a collar 64 which can be set at any desired position and held by a screw. The colbar 68 is in line witha striker 68 carried on the crosshead 35 and thus, when the ram 34 is caused to be retracted by depression of the lever 54, the movement will proceed until the striker 68 engages the collar 68 and withdraws the latch 65. Thereupon (since the relay 4i will have been de-energised in the meantime by the fact that the workpiece has been severed and that the electric eye" 40 is no longer focussed upon a fully heated portion of the workpiece) the lever 54 will be forced upwardly by the spring 64 and the movement of the ram will be reversed so as to bring it forward into position ready to operate upon a new workpiece. The throttle valves 59 and Bi serve to regulate the speed of movement of the ram, the one in the one direction and the other in the other and thus to determine the speed of the forging operation and the time taken for the return movement, which latter should be sumcient to permit the operator to prepare for the insertion of another workpiece.

The extent of the movements of the ram in both directions is limited by stops. The adjustable rod 10 which is able to slide in a boss Ii on the top of the cylinder 31 constitutes a back stop to prevent undue retraction of the vice l6 and the two screwed rods I2 which pass through the the crosshead 'II are provided with heads I! to constitute a front stop. The heads ll carry sprockets II which are connected by chains II and one of the spockets has a handle II. By this means the two screws 12 can be simultaneously rotated to an equal extent and brought into any desired position of adjustment.

The vices I8, H are controlled from the valve box I! by a lever 11 parallel to the lever l. The lever 'II operates the valves in the valve box I! which serve to admit fluid under pressure to the pipe ll leading to the upper endof the cylinders 2| when the lever is depressed, while at the same time connecting the pipe IO, connected to the lower ends of the cylinders, to the exhaust pipe 62. Depression of the lever II will therefore close the vices I6. II simultaneously upon the workpiece. On the other hand, when the lever ;is raised into the position indicated in Figure 3 the connections of the pipes and I! to pressure and exhaust respectively will be reversed and the vices will be opened to release the workpiece, or rather the portions of it which remain in the vices after the forging operation.

The pressure which is applied for holding the workpiece and for the forging operation can be regulated by means of a by-pass relief valve .0

on the delivery side of the pump 56. The relief valve has a screwed stem ll screwing down of which modifies the pressure of the relief valve spring and thus determines the hydraulic pressure at which the system operates.

On a branch 82 from the pipe 18 there is connected a switch control cylinder 83. This contains a piston and a return spring 84 and serves to operate a piston rod 85 in such a way that the presence of hydraulic pressure will cause the rod II to be pressed forward out of the cylinder into the position shown in the drawings. The rod 85 is connected to two switch arms 88, 81 of a double-pole switch in the supply circuit to the transformer winding 48. Failure of the hydraulic pressure will therefore lead immediately-to the current being cut of! but as long as the pressure is maintained in the pipe I8 and the vices are therefore closed, the transformer will be energized, subject of course to the control of the clapper switch 41 already described.

In addition to the controls already described there is a push button 90 which normally closes the circuit leading from the relay through the wires 43, 44, but which, when pushed, breaks this circuit and makes another through the wires 9|, 92 which by-passes the relay II and energizes the solenoid 52 as an alternative to the energisation of this solenoid by the relay. Consequently the operator, if he desires, can cut out of operation the "electric eye" 40 and cause the transformer '48 to be tie-energised by operating the push button 90, at the same time applying the tension forging force to the workpiece through the action of the solenoid 52. In this case the control of the operations is effected by hand instead of automatically by the electric eye."

In the operation of the apparatus therefore the operator begins with the levers 54, II in their uppermost position as indicated in Figure 3. The vice jaws I9, 22 of both vices will then be open and the ram 36 will be advanced to its full extent. After placing a workpiece I8 in position, the operator depresses the lever I'I, thus closing the vices and actuating the hydraulic switch 81 to close the transformer circuit. As soon as the work reaches forging temperature the electric eye ll operates the relay ll and breaks the transformer circuit by de-energising the clapper switch magnet it. At the same time the relay Menergises the solenoid l2 and draws a down the lever ll, thereby setting the ram in movement to draw the vice I6 away from the vice a I1 and cause the work to be drawn out. with the normal setting of the parts, this movement will continue until the workpiece is drawn out to 7 two pointed pieces somewhat similar to the lilustration in Figure 5, although the degree of 10 taper of the point depends not only upon the temperature of the workpiece but also upon the distance apart of the vices before the'operation is commenced and the speed of the 'drawing-operation, which latter can be regulated by means of the throttle valves '59, ii. If it is desired merely to forge a thinner place in the workpiece, and not completely to sever it, the stop III is adjusted to terminate the motion before the workpiece has been fully severed.- Immedigo ately before the'end of the movement of retraction of the ram 36 the striker 69 is made to engage the collar 60 and, withdraw the latch 65, thereby permitting the lever 54 to rise and causeing the ram I8 to stop and to begin a forward movement. The operator raises the lever ll, thus opening the vices I6, I1 and removes the workpiece. If the throttle valve 6| is suitably adjusted he will have time to insert another workpiece before the ram 36 completes its forgo ward movement, upon the termination of which he will lower the lever 11 again and thereby close the vices upon the workpiece. Thereafter the recommencement of the drawing operation depends upon the workpiece acquiring the appro- 86 priate temperature which is observed by the "electric eye I, or altemativelyby the operator. A

It should be observed that if desired the screw 25, which serves to adiust the vice Il, may be made hollow so that a long length of bar can be fed into the vice jaws through the screw, and in that case a series of workpieces could be severed one after another by feeding in a fresh piece of bar between the vices after each severing'opa workpiece III may be held and heated as already described. In addition to the clamping jaws the vices have supporting ball bearings I20 which surround the workpiece and are able to support it for rotation even after the vice jaws 9 have been released. Between the vices H8, 5

I I! there are mounted two cradles I2I, I22 which are pivoted below the workpiece and extend upwardly one at the front and one at the rear as illustrated in Figure 4 and carry at their upper ends on each side of the workpiece rotatable swaging rollers I23. The swaging rollers are mounted on spindles the axes of which are parallel to the axis of the workpiece Ill and the spindles I24 carry at their ends sprockets I25. The sprockets are driven bychains I28 from a larger sprocket coaxial with the pivot of the cradles I2I, I22. The cradles are capable of being rocked so as to advance the swaging rollers I23 into contact with the workpiece II! by means of a rightand left-hand screw I21 which 1' piece similar to the electric eye" ll ofl'igures 1 to 3. In the operation oi the device the workpiece is first heated by applying the current after the vices H6, ill have been closed together upon the workpiece. As soon as the work becomes hot enough for forging, the electric eye" operates a relay similar to the relay 4i and the vices are so connected that the vice Jaws II! are released from the workpiece, thus freeing itfor rotation. At the same time the rollers I23 are set in motion and the operator, as soon as he sees these events happen, actuates the hand-wheel I28 to close the swaging rollers I23 upon the workpiece. The swaging rollers, since they are being rotated and the workpiece is rotatably mounted in the bearings iZG, will cause the workpiece to rotate while they are being forced inwardly into it and as a result the workpiece is swaged to a shape similar to that shown in Figure 5 and the two halves are separated from one another. Thereafter the swaging rollers are withdrawn and the workpiece is taken out of the electrodes H6, H1. It will be understood that with this arrangement the vice jaws do not move along the bed on which they are mounted and, except for some means of longitudinal adjustment, no necessity exists for such longitudinal movement. The cylinder 3! and ram 36 would therefore be omitted from such a construction.

While a particular shape of swaging roller has been illustrated which is adapted to produce points like the end of a projectile, it will be understood that any other shape of swaging roller could be'adopted if desired. The action of the rollers can be assisted if desired, by applying tension, providing the vice I I6 is made longitudinally movable. Tension applying means similar to that hereinbefore described may be employed for this purpose.

I claim:

1. An electric forging apparatus comprising in combination two work-holding vices for gripping a workpiece at separated points along its length, means for supplying electric current to the workthe workpiece through said gripping means to heat the workpiece, means for applying force to the workpiece to deform and reduce the section thereof, and means responsive to a predetermined increase in temperature of said workpiece for simultaneously reducing the supply of electric current thereto and initiating operation oi said force applying means thereon.

3. Electric forging apparatus comprising in combination two work-holding vices for gripping a workpiece at separated points along its length, means for supplying electric current through the work-holding vices to the workpiece to heat the latter, means for rotating the workpiece about its own axis, swaging rollers mounted so as to be applied to the workpiece to reduce the section thereof, and means responsive to a predetermined increase in temperature of the workpiece for reducing the heating current, for applying the swaging rollers to the workpiece, and for initiating operation of said workpiece rotating means.

4. In an electric forging apparatus, the combination with means operable to grip a workpiece, of means for supplying electric current to the workpiece through said gripping means to heat the workpiece, means for applying force to the workpiece to deform and reduce the section thereof, electrical means for simultaneously initiating operation of said force applying means and reducing said heating current, means including a thermal device responsive to rise in temperature of said workpiece for energizing said electrical means, and manually controlled means for energizing said electrical means independently of the operation of said thermal device.

ELAERIC GASPAR.

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