US2422928A

US2422928A - Electrical forging machine

Info

Publication number: US2422928A
Application number: US604684A
Authority: US
Inventors: Rogati Carlo
Original assignee: OMES Ltd
Current assignee: OMES Ltd
Priority date: 1944-04-20
Filing date: 1945-07-12
Publication date: 1947-06-24
Anticipated expiration: 1964-06-24

Description

June 24, 1947. i ROGATI 2,422,928

ELECTRICAL FORGING MACHINE Filed July` l2, 1945 5 Sheets-Sheet l LL N si I I June 24, 19047. CQ ROGATI ELECTRICAL FRGING MACHINE 5 sheets-sheetl 2 'Filed July'lZ; 1945 INve/vrok @wld 54a wma-W, v I i um June 1947. Q ROSAT;

ELECTRICAL FORGING MACHINE 5 sheets-sheet 3 Filed July 12, 1.945

INvefvTof? Patented June 24, 1947 ELECTRICAL FORGING MACHINE Carlo Rogati, London, England, assignor to Omes Limited, London, England, a British company Application July 12, 1945, Serial No. 604,684 In Great Britain April 20, 1944 5 Claims.

This invention comprises improvements in or relating to electrical forging machines. It has?, always been difficult, in electrically heating workpieces which are held between electrodes, to ensure that the electric current enter-s the workpieces symmetrically, that is to say equally from opposite sides and especially is this the case when large workpieces are operated upon. One reason for this is that under the low voltages employed and with the very large currents necessary, small diiierences of resistance in the current leads orV at the contacts or elsewhere have a marked effect; another reason is that the use of alternating current is a necessity and with large alternating currents under low voltages any difference in length of path of the current to different sides of the workpiece results in a difference in the inductive impedance to the current flow and therefore to a corresponding difference in the current distribution. Inasmuch as the transformer which supplies the current must be located to one side of the Work, these differences are diicult to obviate. Especially at work-holding vices, which are also used as electrodes, there is difficulty in ensuring that both vice-jaws supply equal amounts of current to the work.

The present invention comprises, in an electrical forging machine the combination of a viceelectrode having two work-gripping vice-jaws, with a transformer having a secondary winding, one end of which is out symmetrically by the plane of division between the two vice-jaws and iiexibly connected to each of the vice-jaws, the connection to each vice-jaw being taken from the portion of the end of the Winding which lies on the same side of said plane as the jaw to which it is connected.

In one construction according to this invention the vice-electrode may be constituted by jaws of high-conductivity metal held in a viceframe of low-conductivity metal. Hitherto, ordinarily, vice-frames have been made partof the electrode, being made of high-conductivity metal directly secured to transformer terminals, but the use of distinct vice-jaws which constitute the electrode, so that the vice-frame is not directly connected to the transformer secondary, tends to confine the eurent to the jaws and workpieces and to limit irregularities of distribution arising from the necessarily irregular shape of the vice-frame.

When the invention is to be applied in upsetting the ends of workpieces or in heating the ends of billets an anvil-electrode may be provided in line with the vice-electrode,` the other end of the secondary of the transformer being disposed in the same plane as the first, close to the anvilelectrode, and iiexibly connected thereto by connections symmetrical about the said plane.

If billets are to be heated at intermediate points between their ends two vice-electrodes each constructed as already described may be employed for gripping the workpieces at two places..

The following is a description, by way of example, of a construction of an electrical forging machine embodying vice-electrodes according to the present invention.

In the accompanying drawings:

Figure 1 is a front elevation of a complete upstanding machine embodying the present invention;

Figure 2 is a view oi the vice of the machine showing some of the parts illustrated in Figure l as viewed from the right in that figure;

Figure 3 is a detail relating to the current connections to the vice;

Figure 4 is a further detail of the same;

Figure 5 is a detail of the current connections to the anvil.

Figure 6 is a diagram showing the disposition of the transformer.

The machine comprises a base plate II which is intended to rest on the foundations of the machine. On the platform at one end thereof is bolted a headstock, or guide-bar support, I2 which incorporates a cylinder block I3 containing a horizontal hydraulic ram I6 and securing means flor two horizontal guide-bars I4, I5. At the other end of the bed-plate I I is another headstock Il incorporating a cylinder block I8 which contains a second hydraulic ram I9, axially in line with the iirst and securing means for the other ends of the horizontal guide-bars I4, I5. The two horizontal guide-bars I4, I5 are arranged so that one of them lies in a horizontal plane below the level and in front of the cylinder axis and the other is above the cylinder axis but to the rear thereof as can readily be seen in Figure 2. The two guide-bars therefore lie in an inclined plane which extends downwardly towards the front of the bed-plate of the machine; the axis of the ram cylinders I3, I8 is disposed in this inclined plane.

The guide-bars I4, I5 pass through the cylinder blocks I2 and Il from end to end and are secured at the outer end by tension nuts I9, 20. Any compression forces exerted by the rams upon the workpieces held in the machine are wholly taken up by the guide-bars in tension and the reaction does not come upon the machine bed II.

The hydraulic ram I9 of the cylinder block I1, which is at the left-hand end of the bed-plate l I as viewed in Figure 1, is double-acting and has a long stroke; it is used for feeding the stem of the workpiece forward during the upsetting operation. The hydraulic ram I6 at the right-hand end of the bedplate is used to support an anvil 2 I. Upon the bedplate between the two rams and nearer to the ram I there is supported a vicecarrying casting 22. The vice-carrying casting has bosses through which the guide-bars pass and a web 23 connecting the bosses, which web is cut away at 24 in the centre between the upper and lower guide-bar to permit ready insertion of workpieces. A web 25 between and at right angles to the two guide-bars carries a bracket 26 which extends laterally from the web toward the anvil electrode and supports a fixed lower vice-jaw 21. The upper surface of this bracket 26 to which the vice-j aw is bolted is horizontal. Above the bracket and in front of the upper guide-bar I5 there is bolted to the web a vertical ram cylinder 28 carrying a hydraulic ram 29 which projects downwardly and carries a movable upper vice-jaw It will therefore be seen that the vicejaws are sub-divided horizontally and that the Vice lies in effect at the bottom behind the lower guide-bar and at the top in front of the upper guidebar. This arrangement makes for convenience in the insertion of the workpieces by the operator which is not otherwise easily achieved in a construction employing guide-bars. The two vice-jaws 21', 36 are made of high-conductivity copper alloy and have extensions 3I, 32 which pass below the upper guide-bar I4 rearwardly towards a transformer located on the same level at the back of the machine, and shown in Figure The upper and lower high-conductivity vice-jaws are made electrically identical with each other, that is to say they are of the same external dimensions and mass of metal and their connections to the secondary winding 16 of the transformer are made symmetrical so that the same current distribution will proceed to each vice-jaw, a result which has hitherto been difficult to secure. The body of the vice, that is to :ay the bracket the web 23 and the hydraulic cylinder are made cf cast iron or steel.

The extensions Si, 32 terminate in enlarged terminal blocks 1I, 1E rear i'ace of the block 1i. This face has six recesses machined out oi it which are tapered. The tapered recesses are shown in the detail Figure 4 13, in each recess is a thimble 15 and the thimbles 'i5 are soldered to the ends of heavy f stranded copper cables 16. The cables i5 are hunched together and led around the core 6I of the transformer so that the cables themselves constitute the secondary winding of the transformer. The thimbles are held in place in the blocks 1i, 12 by

dat bars

11, 18, 16 which are placed so that they partly overlie the edges of the thimbles and extend close to the stranded cables i6. The

bars

11, 18, 19 are held in place by set screws 86. The thimbles 15 are tapered so that they t the tapered recesses 13, 14 in the backs of the portions 1i, 12 of the extensions 3l, and thus good electrical connection is made to the vice-jaws. This connection is exactly symmetrical to the upper and lower vice-jaw and therefore the two jaws will get an equal amount of current. When, as in the generally adopted previous constructions, the transformer is located below the vice, with guide means for supporting the vice and anvils arranged horizontally on each and Figure 3 shows the f 4 side of the vice, the connections to the upper vicejaw have necessarily been longer than those to the lower vice-jaw so that the current distribution could not be symmetrical to the two jaws.

It will be observed that the vice-jaws 21, 3U contain liners BI, 8i; and these liners may themselves contain bushings 83 which are of such a size as to t the bar which is to be upset. The bushings 3 are made readily renewable. The liners are held in place by means of plates 85 and sliding dogs 86.

On the side of the web 23 of the vice casting there are two bosses 33, 34 in which are secured the ends of control rods 35, 36 which extend parallel with the guide-bars I4, I5 to the headstock I1 of the ram I9, to which headstock they are also secured. The control rods 35, 36 lie in the same inclined plane as the guide-bars and between these bars; they are screwed for a length corresponding to the upsetting stroke and carry two stop nuts each, 31, 38. Mounted to slide upon the guide-barsand working between the stop nuts is a crosshead 3S to which is bolted the ram i9 of the hydraulic feed cylinder. The rain i9 is double-acting, with a large area behind io exert forging pressure when it is moved toward the anvil and a small annular area between the piston rod of the ram and the walls of the cylinder i8 for purposes of retraction. On the crosshead, and coaxial with the ram, there is secured on the side toward the viceq'aw a thrust block 4t and in the thrust block there is screwed work-engaging pad 4I having a recess to fit the end of the workpiece. A number of such or different sizes may be provided to t different workplaces. The stroke of the ram in both directions is limited by the

stop nuts

31, 38 on the control rods 35, 36. It may also be controlied by automatic limit switches or hydraulic pilot valves if desired.

Turning to consider the anvil-carrying ram I6 mounted at the right-hand end of the bed-plate, this ram is also double-acting and is secured to a crosshead 42 which slides upon the guide-bars of the machine between the ram cylinder and the vice already described. To the crosshead there is bolted an anvil carrier 43, the anvil carrier being insulated from the crosshead by appropriate insulating packing 44 and by insulating bushings in the holes which receive the securing bolts 45 or studs. It is this insulated anvil carrier and the anvil 2I clamped to its face alone which are made of high-conductivity material and the carrier 43 is provided with a rearward extension 46 which passes through the space below the upper guide-bar I4 and ends in a terminal block 41 arranged close to, and in the same vertical plane as, the terminal portions 1I, 12 of the upper and lower vice-jaws already described. One end of the secondary winding 16 of the transformer is connected to this terminal block 41 and the other end symmetrically connected to the terminal portions 1I, 12 of the upper and lower vice-jaws. The secondary winding of the transformer is therefore arranged in a horizontal plane as shown in Figure 6 and the magnetic circuit (the core 6I) passes vertically through it. The primary winding of the transformer is indicated at 62. The other ends of the stranded cables 15 from those which are secured to the blocks 1 I, 12 are soldered into thimbles 15 similar to those already described and these are secured in tapered sockets in the terminal block 41 by means of bars11 and set-screws 80 in a similar manner to that already described for the other ends of the cables. This ensures an effective and satisfactory current distribution to the anvil 2|. Although the current enters the side of the anvil carrier 43, it has to travel into the anvil 2| itself in an axial direction and will therefore be transmitted uniformly over the anvil face. Thereforeby the described arrangement of the electrodes of the machine the anvil is symmetrically fed with current as well as the vice-jaws, and the workpieces therefore readily become heated evenly throughout their cross-section.

The crosshead of the anvil-carrying ram has secured in it a pair of control rods 48, 49 which extend rearwardly towards the headstock l2 in which the ram is mounted so that these rods move with the crosshead. They pass through holes in the headstock and carry stop nuts 5D, 5| in front of and behind the lugs, so that the stroke of the ram is limited in both directions and can be adjudged by the operator.

Control valves having hand levers 52, 53 are provided for the two hydraulic rams I6, |9 respectively and a valve having a lever 54 for the vice-electrodes. The control for the vice-electrodes may be linked in known manner with the control for the work-feeding ram I9 so that when the operator closes the vice-jaws on to the work hydraulic pressure is applied to the work-feeding ram to urge the workpiece towards the anvil. As soon as the workpiece reaches forging heat in the space between the vice and the anvil 2|, the ram begins to feed it through the vicejaws and to form an upset head against the anvil 2|. The control 52 of the ram which carries the anvil is independent of the controls 53, 54 l and is so regulated by the operator as to allow the anvil to recede slowly as the upsetting operation progresses so as to provide space for a head of the size desired.

Both the vice-jaws and the anvil can be provided with connections for water-cooling if desired and the vice-jaws may be provided with removable inserts held in place by special clamping means.

An electric motor 60 bolted to the bed-plate drives a hydraulic pump within the bed-plate which supplies the hydraulic fluid under pressure required for operating the rams. The details of the hydraulic connections are common practice and do not require description.

If desired a steady rest 6| may be mounted on the guide-bars I4, |5 between the vice 22 and the crosshead 39 and may be provided with clamping devices for holding the centre of a long bar supported between the vice 22 and the thrust block 4| steady While it is being pressed forward by the ram I9.

I claim:

1. In an electrical forging machine the combination of a frame comprising guides, a vice electrode supported on the guides comprising two work-gripping vice-jaws, one movable toward and from the other and means to operate said movable vice-jaw, the vice-jaws when closed being separated along a, plane of division, a second electrode supported by the frame and insulated from the first electrode, said second electrode being located so as to be symmetrically cut by said plane of division, means to move one electrode along the guides relatively to the other, and a transformer comprising a secondary winding located so that it is symmetrically cut by said plane of division, one end being connected as to the part lying on one side of said plane to one vice-jaw and as to the part lying on the other side of said plane to the other vice-jaw and the other end of said winding being connected to the second electrode.

2. The combination according to claim 1 wherein the second electrode is an anvil-electrode in line with the vice-electrode.

3. The combination according to claim 1 wherein each vice-jaw has a lateral extension terminating in a terminal block having a fan which extends normally to the plane of division between the vice-jaws, the faces of the two terminal blocks being aligned on opposite sides of said plane, and means for attachment of one end of the transformer winding directly to said faces.

4. The combination according to claim 1 wherein the second electrode is provided with a lateral extension terminating in a terminal block having a face which extends normally to the plane of division between the vice-jaws and equally on either side thereof, and means are provided for attachment of one end of the transformer winding directly to said face.

5. The combination according to claim 1 in which the vice-electrode comprises jaws of high-conductivity metal held in a vice-frame of low-conductivity metal.

CARLO ROGATI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,658,056 Phelps et al. Feb. 7, 1928 2,328,742 Rogers et al. Sept. '7, 1945 2,344,939 Bennett Mar. 28, 1944 FOREIGN PATENTS Number Country Date 448,426 Great Britain June 2, 1936