US3271991A

US3271991A - High energy impact machine

Info

Publication number: US3271991A
Application number: US494781A
Authority: US
Inventors: Frederick A Monahan
Original assignee: International Electronic Research Corp
Current assignee: International Electronic Research Corp
Priority date: 1965-10-11
Filing date: 1965-10-11
Publication date: 1966-09-13
Anticipated expiration: 1983-09-13

Description

p 13, 1966 F. A. MONAHAN 3,271,991

HIGH ENERGY IMPACT MACHINE Filed Oct. 11. 1965 4 Sheets-Sheet 1 /I I PROGPHMMEP IOI 70 fvvE/v r02. Eeeosmcx H. Ma/vm/m/ A'rroelvsys.

. p 1966 F. A. MONAHAN 7 3,271,991

HIGH ENERGY IMPACT MACHINE Filed Oct. 11, 1965 4 Sheets-Sheet 2 f FROG/PH Hwy? .f/VVEN r02. E QEDER/c/e AI. MONA/MN I2 15% a M" p 13, 1966 F. A. MONAHAN HIGH ENERGY IMPACT MACHINE 4 Sheets-Sheet 3 E200 Filed Oct. ll, 1965 .lZ r

INVENTOR- FEDEQ/CK H. MON/4H9 (51% y M firroeA/Eys.

p 13, 1966 F. A. MONAHAN HIGH ENERGY IMPACT MACHINE 4 Sheets-Sheet 4 Filed Oct. 11. 1965 flrramvsys.

United States Patent 3,271,991 HIGH ENERGY HVIPACT MACHINE Frederick A. Monahan, Burbank, 'Calif., assignor to International Electronic Research Corp., Burbank, Caliii, a corporation of California Filed Oct. 11, 1965, Ser. No. 494,781 18 Claims. (Cl. 72-453) This is a continuation-in-part of Ser. No. 137,409, filed September 11, 1961, now Patent No. 3,222,914, granted December 14, 1965.

The present invention relates to an impact apparatus, and more particularly to a high energy impact machine for utilizing a fluid medium under pressure to exert controlled impact forces upon a material or workpiece.

Impact formation of materials is a comparatively recent development for forming and shaping certain of the newer, high strength materials which cannot be formed in a practicable manner by any other process. Of the impact devices currently available for impact forming of materials, one of the most eflicient is based upon the counterblow principle, in which a pair of hammers are rapidly brought toward each other to bring dies supported thereon into forcible engagement at very high velocities. The kinetic energy of the hammers is transferred to the workpiece during movement of the hammers so that, depending upon the relative masses of the hammers, very little of the impact forces is transferred to the hammer support structure. Such counterblow devices have certain shortcomings which limit their usefulness and complicate their operation.

More particularly, the counterblow devices of the prior art are substantially all characterized by high initial impact, followed by a very rapid drop-off of follow-up or squeeze pressures, and high initial impact forces frequently' shatter the workpiece or break the dies. Depending upon the nature of the material of the workpiece, the shape of the workpiece, and the forming operation involved, a variety of impact-squeeze relations-hips might be desirable, but prior art devices are not adapted to provide an adjustment of impact-squeeze relationship to suit the momentary need. That is, either the kinetic energy of the hammers is all absorbed by the workpiece in one impact, or this energy is all transferred to the workpieces in a relatively slow squeeze.

Further, the valving arrangements of prior art impact devices commonly employ small area valves which require comparatively long strokes to produce orifice cross sections adequate to pass suflicient pressurized fluid for rapidly driving the impact hammers together. During initial hammer travel the pressure fluid thus flows through a relatively small orifice which gradually increases as the valve opens and the hammer stroke continues. Such valving arrangements have the inherent limitation of being incapable of initially and substantially instantaneously passing a sufiicient volume of fluid under pressure to achieve high final impact velocities for large hammer masses. Desirably, such impact devices should have a large orifice for passage of pressurized fluid after only a short opening movement of the valve or valves, and prior to any appreciable movement of the hammers has occurred.

Therefore, it is an object of the present invent-ion to provide a new and improved high energy impact machine which is adjustable to provide a variety of impact-squeeze relationships for various forming operations and for various materials.

Another object of the invention is to provide a new and improved impact apparatus which includes an annular valve which is arranged about the periphery of the hammer sections to permit achievement of a very large annular orifice area after minimum valve movement, providing maximum pressures substantially instantaneously.

The present impact forming apparatus also, in one embodiment, incorporates the pressure reservoir in one of the hammers so that long connecting conduits and similar fluid pressure limiting devices are eliminated, the fluid pressure being available immediately adjacent the hammers for actuation thereof, the integration of the fluid pressure reservoir in one of the hammers providing a means for adjusting the mass of that hammer, as by dividing the reservoir into two compartments, one for liquid mass and one for pressurized fluid. The object also includes pressurizing the liquid mass to provide the pressurized working fluid, and pressurizing the gaseous material of the other compartment to provide a pressure accumulator arrangement.

Another object of the invention is to provide a new and improved impact apparatus which employs a pair of hammers movable toward each other at very high velocities under the impetus of fluid under pressure, and Wherein one or both of the hammers may be multiple hammers; that is, a hammer including a plurality of hammer sections, wherein each pair of sections defines a pressurizable chamber which enables adjustment of the impactsqueeze work diagram upon the workpiece between the hammers. More particularly, the object includes engagement of the main hammers divided into an impact blow, that is, a blow of relatively short duration, and a squeeze blow of longer duration, according to the magnitude of the pressure within the pressurizable chambers intermediate each pair of the hammer sections of the hammer. Thus, in an embodiment employing an upper hammer opposed by a lower hammer constituted by a pair of hammer sections, the initial impact on the workpiece is provided by the upper section of the lower hammer striking the upper hammer. The subsequent follow-up or squeeze pressure is provided by the mass of the lower hammer section of the lower hammer. The mass of the lower hammer section is effective to provide a steady build-up or squeeze pressure if the pressure in the intermediate chamber is fairly high, or provide a second impact blow closely following the initial impact blow it the intermediate chamber pressure is low.

Another object of the invention is the provision of an impact apparatus which eliminates work spoilage by controlling the rebound or separation of dies subsequent to an impact blow such that any rebound or re-hit occurs between sections of the hammer or hammers rather than between the hammers themselves.

Another object of the. invention is to provide an impact apparatus which is capable of withstanding considerably more eccentric loading than similar apparatus of the prior art, namely by providing large diameter hammer areas which furnish a broader, more stable base for the apparatus wherein the pressure areas are not correspondingly as large because they are made annular in form, thereby avoiding the need for impractical large quantities of pressure fluid.

Another object of the invention is the provision of an impact machine which incorporates damping means for reducing rebound or re-hit oscillations between the impact elements or hammers.

A further object of the invention is to provide an impact apparatus in which the hammers cannot be actuated for an impact stroke except by deliberate operation of a plurality of separate valves, the apparatus being characterized by a fail-safe design such that any malfunction of the valves prevents operation of the impact apparatus,

Another object of the invention is to provide an impact apparatus which is adapted to form and shape workpieces in a controlled atmosphere devoid of workpiece contaminants, and wherein a door seals the workpiece forming area, and also functions as a safety door to protect operators from flying material, such as might occur when the impact apparatus is used for hobbing operations.

Also included among the objects of the invention is to provide a new and improved high energy machine which includes one or more squeeze chamber combinations such as, for example, a squeeze chamber operating in part by hydraulic pressure or a squeeze chamber operating in part by purely mechanical pressure, as for example, by employment of special springs.

Further included among the objects of the invention is to provide a new and improved high energy impact machine wherein one or more multiple type hammers are built in such fashion that the platen, or work carrying plate, is capable of adjustment to lengthen or shorten the blow or, in the alternative, to be completely removable for replacement by a plate member which may include a rubber pad thereby to make possible employment of a high energy machine for sheet metal forming and its attendant advantages.

Also included among the objects of the invention is to provide a high energy impact machine of such design and construction that the main valve is entirely separate and apart from the ram and separately adjustable, and further to provide for the application of work pressure in such fashion that, by use of a programmer if need be, the de vice may be made capable of multiple repeated and successive work strokes of variable magnitude.

Included further among the objects is to provide a new and improved control for a high energy impact machine by means of which the platens can be inched in short increments as they are advanced to a work contacting position by one or another of several expedients thereby to facilitate adjustment of dies in the machine.

With these and other objects in view, the invention consists in the construction, arrangement, and combination of the various parts of the device, whereby the objects contempiated are attained, as hereinafter set forth, pointed out in the appended claims and illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 is a longitudinal sectional view of a diagrammatic representation of the high enregy impact machine showing the hammers in initial or withdrawn position.

FIGURE 2 is a longitudinal sectional view similar to FIGURE 1, but showing the hammers in impact position.

FIGURE 3 is a fragmentary longitudinal sectional view of the midportion of the machine, taken on one side, as for example on the line 3-3 of FIGURE 4.

FIGURE 4 is a fragmentary cross sectional view taken on line 4-4 of FIGURE 3.

FIGURE 5 is a longitudinal sectional view on a reduced scale showing the machine in a horizontal position.

FIGURE 6 is a fragmentary longitudinal sectional view of the upper hammer section wherein the platen has been provided with a rubber impact plate.

FIGURE 7 is a fragmentary longitudinal sectional view of another form of composite lower hammer capable of use with the device when hydraulic squeeze pressure is employed.

FIGURE 8 is a fragmentary cross sectional view taken on the line 88 of FIGURE 7.

i In the field of high velocity press work, wherein one hammer hits another hammer or anvil with a workpiece inbetween, and wherein velocities of impact are far in excess of those encountered with presses using freely falling hammers, the existing art has not yet advanced sufiiciently to provide many desirable operating characteristics. Although such subordinate operating characteristics are relatively simple to provide in theslower moving devices, provision of comparable operating characteristics in high velocity press work encounters many obstacles and exceptional problems. In the forms used in the low velocity art, as evidenced by sundry existing patents, such desirable features would be unworkable in a high velocity application without incorporation of novel modifications specific to the peculiarities of high speed and extremely short time durations which are in the order of th and 1000th of a second.

Although illustrated diagrammatically the diagrammatic representation structurally and functionally follows applicants present commercial form of the machine. As a somewhat broad basic concept, the chosen embodiment of the machine herein depicted for purposes of illustration may be considered as housed within a closed substantially cylindrical frame 10 mounted in a relatively light weight base 11 which in turn rests upon a supporting surface 12. There are two composite hammers mounted in the frame. The upper composite hammer is indicated generally by the reference character 13 and the lower composite hammer is indicated generally by the reference character 14. It will be helpful to understand that the upper composite hammer 13 is housed entirely within a surrounding portion of the lower composite hammer 14 and that these two hammers move-toward and away from each other and also that both hammers move with respect to the frame 10. v

Within the upper portion of the frame 10 is a composite construction of parts in concentric relationship which constitutes a system of valving indicated generally by the reference character 15, some parts of which move with the hammers and other parts of which remain stationary with respect to the fname. The hammers are pneumatically operated and the system of valving is also operated pneumatically. A high pressure supply line 16 introduces air under a high pressure to a reservoir chamber 17 and it is air from this reservoir chamber which is valved to a pressure chamber 18 for the purpose of manipulating the

hammers

13 and 14. Air for operating the system of valving is supplied through an operating fluid supply tube 19. In the chosen embodiment, the hammers are shown, in FIGURE 1, poised and ready to perform work upon a workpiece 20. In this connection, attention is also directed to FIGURE 2 wherein the pressure chamber 18 is shown greatly enlarged as it would be after admission of high pressure air from the reservoir chamber 17. The

upper composite hammer 13 has moved downwardly inside of the lower composite hammer 14 which in turn has moved upwardly, and the workpiece 20 has been deformed into the shape 20' as indicated in cross section in FIGURE 2. After the blow illustrated in FIGURE 2,

air from the pressure chamber 18 is exhausted through a main exhaust passage 21.

In normal position prior to firing, the hammers are separated from each other at rest in the relative positions shown in FIGURE 1. In this position air under relatively high pressure, which may be from 1000 to 2000 pounds per square inch, is introduced through the high pressure supply line 16 to the reservoir work chamber 17. The system of valving 15 is closed. To accomplish this, a sleeve valve 22 is made use of, mounted upon a valve guide 23 by means of a spider 24. The valve guide 23 is slideably supported upon the operating fluid supply tube 19 which is stationary with respect to the frame 10 and which extends downwardly through a top plate 25 of the frame. A series of circumferentially spaced ports 26, two of which are shown in FIGURE 1, are normally closed by the sleeve valve 22. To shift the sleeve valve 22 upwardly in order to open the ports 26, a three-way valve 27 in the operating fluid supply tube 19 is opened and operating fluid is admitted into an operating cavity 28 which is located on the upper side of the upper composite hammer 13. Operating pressure thus acting upon the bottom surface of the valve guide 23 shifts the sleeve valve suddenly upwardly uncovering the ports 26 and air under pressure in the reservoir chamber 17 is immediately released to the ports. Although the outer ends of the ports appear to be covered by a neck 29 on an upper plate 30 there is actually sufficient clearance to permit.

the air under pressure to pass into the pressure chamber 18. There are a suflicient number of ports 26 of large capacity so that as soon as the sleeve valve 22 is shifted to open position substantially the entire content of the reservoir chamber 17 is, in effect, suddenly dumped into the pressure chamber 18 and the composite hammers are substantially instantaneously actuated. When this happens the composite hammers 13 and 14 assume the relative positions shown in FIGURE 2. In doing this, the lower composite hammer 14 moves upwardly, the main portion of the lower composite hammer sliding upwardly within a bore 31 in the frame 10. At the same time, the upper composite hammer 13 moves downwardly, the lower part sliding within a central chamber 32 of the lower composite hammer 14 and a flange 33 sliding within a recess 34. During this portion of the cycle, an exhaust valve 35 in the main exhaust passage 21 is closed.

Thereafter, in order to release the hammers and return them to initial position, the three-way valve 27 is turned from operating position to return position so that the operating fluid in the operating fluid supply tube 19 which was previously connected to a supply tube 36 is now switched to an exhaust tube 37. At the same time and by appropriate interconnecting means (not shown), the exhaust valve 35 is opened and the fluid from the pressure chamber is free to pass outwardly through the main exhaust passage 21.

Initially, prior to the work stroke, air under a very low pressure, namely about zero p.s.i. gage when the machine is in vertical position and p.s.i. gage when it is in horizontal position, was present and trapped in a return pressure compartment 39. As the upper plate 30 of the lower composite hammer 14 moved upwardly during the work stroke air in the return pressure compartment 39 was reduced in volume and compressed. The pressure thus created, when the machine is in horizontal position, compensates for the lack of gravity in the axial direction of the two composite hammers, and assists in returning them to initial position.

Automatic return of the hammers to start position is more particularly the function of an annular pneumatic hammer return pocket 40, acting in conjunction with a composite hammer return shock absorbing pocket, consisting of

parts

41 and 42. In the initial position of FIGURE 1, the

pocket parts

41 and 42 are physically separated but are air connected by small diametrical clearance of the plate 30 relative to frame 10. In the position of FIGURE 2, the

pocket parts

41 and 42 have been joined to each other by displacement of the lower composite hammer 14.

Actually the combined action of the pneumatic return pocket and the two parts of the hammer return shock absorbing pocket serves to not only ultimately to assist in returning the hammers to initial position after a working stroke, but also to snub the falling action of the hammers during the final stages of the working stroke. The combined volume of the hammer return pocket and the two parts of the hammer return snubber pocket remain substantially the same throughout the complete cycle of the machine. The volumes, however do change relatively as the stroke progresses. The pneumatic chamber is precharged through a pneumatic pressure charging line 43 controlled by a valve 44. At the same time, an exhaust line 45 is closed by means of a preset pressure relief valve 46. Notice should be taken of a series of return flow passages 47 which are circumferentially spaced around the hammer return pocket and the shock absorbing pocket part 41, as shown to good advantage in FIGURES 3 and 4. Each of the return pressure supply passages is controlled by a reverse action flow control valve, here identified as clapper valves 48. The clapper valves are, in a sense, partial check valves, in that they permit free out ward flow from the hammer return pocket 40 to the shock absorbing pocket part 41, but restrict flow in a reverse direction without, however, cutting off flow entirely, since a restricted reverse flow of air is provided by partial clos-' ing of the clapper valves 48 controlling flow through bleed passages 47.

As a consequence of the structure above identified, when the power stroke comes on the hammer return pocket 40 is reduced in volume and pressure increases. The increase in pressure is then fed outwardly through the passages 47 into the shock absorbing pocket part 41. At the same time, the shock absorbing pocket part 42 is forced upwardly as a result of the work stroke until the shock absorbing

pocket parts

41 and 42 merge, as the volume continues to increase. An incidental benefit of the operation just described is in inch-ing to adjusting position while the platens are being set by a slow motion operation of the control.

After the work stroke has been completed, the

pockets

40, 41 and 42 continue to function as the action takes place, the upper composite hammer 43 being of lesser mass than the lower composite hammer moves considerably further. This means that the space above a shoulder 49 will enlarge only a relatively small amount since, as previously noted, the aggregate volume of the three pockets remains substantially the same and the volumes individually will divide up and reach roughly a balance. For example, while the hammers are still in closed position, should the pressure be slightly too high in the pockets, the entire hammer assembly will lift slightly before stopping its motion. Should the pressure be slightly too low, the entire hammer assembly will lower slightly before balancing, with the dies still closed. The next step is to open the dies. This is accomplished by exhausting pressure from the pressure chamber 18. Exhaust should not take place instantaneously because in that event, the assembly would fall too fast. Hence, it is prevented from falling too fast by the restricting actions of the clapper valves 48. This results in a partial check in the one direction, as previously described. In addition to this retardation, there is a choking effect between the shock absorbing

pocket parts

41 and 42 as the previous merger of the two ceases to become effective and they become separate parts, as shown in FIGURE 1.

In the horizontal position of the machine, the net effect of this act-ion, with respect to returning the hammer parts to initial position, is that pressure built up in the return pressure compartment 39 during the work stroke tends to lower the lower composite hammer 14 from the uppermost position of FIGURE 2 to the lowermost position of FIGURE 1. While this is taking place, air from the

pocket parts

41 and 42 is being forced through the return pressure passages 47 into the hammer return pocket 40. The action of this is to enlarge the hammer pocket 40 moving the upper composite hammer 13 upwardly from the position of FIGURE 2 to the position of FIGURE 1. During this portion of the cycle, the exhaust valve 35 is open and no appreciable pressure remains in the pressure chamber 18.

One of the functions of a high energy press, of the" type hereunder consideration, is to be capable of forging workpieces without much draft. This means that the dies must be forceably pulled apart after the forging operation. This is accomplished by action of the pneumatic hammer return pocket which has just been described and without which there would be insufficient pulling apart of the dies.

On those occasions where the dies may stick only momentarily and suddenly release, there is an additional problem needing solving, in that the upper composite hammer would rise too rapidly and the lower composite hammer would fall too rapidly. The remedy for this is supplied by the clapper valves which keep the air from entering too rapidly into the hammer return pocket 40. At the same time, the lower composite hammer will not return too fast because it will be cushioned by air trapped above the shoulder 49 in the shock absorbing pocket 42. The last mentioned cushioning or choking effect is, in a sense, a safety feature, in that it reduces the shock although it does not eliminate it entirely.

An additional safety feature is also incorporated in the machine for such occasions as, for example, when restricted return flow valves like the clapper valves 48 areomitted or when they may not be operating properly. At the top of the frame is a snubber compartment 52 lying between the top plate 25 and a plate structure 53 which is, in reality, an extension of the upper composite hammer 13. As the plate structure 53 elevates, the action, obviously, is to cushion the end of the return stroke.

Additionally there is another safety feature in the adjacent upper portion of the frame. This consists of a downwardly open annular snubber recess 54 which surrounds a sleeve 55 connecting the plate structure 53 to the main portion of the upper composite hammer 13. In initial position of the hammers, the snubber recess 54 opens into the return pressure compartment 39. During the work stroke, however, and as the upper plate of the lower composite hammer 14 rises, a flange 56 which fits snugly into the snubber recess 54 seals Off the recess from the return pressure compartment 39 and as it continues to rise, the air trapped in the recess 54 will cushion that portion of the working stroke. Compression of air in the recess 54 also assists in returning the hammer parts from the fully extended position at the end of a work stroke. Actually there is relatively little pressure in the recess last mentioned, but there is so much volume and the movement of the hammers is so fast that cushioning takes place as a result.

To aid further in an understanding of the operation of the parts above described, let it be assumed for example, that the machine is operating in a horizontal position, such as that shown in FIGURE 5. In this position, there will be no gravity action to help return the lower composite hammer to its initial position. Nevertheless, the 15 pounds per square inch pressure in the return pressure compartment 39 will become operative because there is an abudance of area over the upper plate 30 against which the pressure can operate. This will cause return of the lower composite hammer. The upper composite hammer 13 is moved in the same relative direction as heretofore described as a result of pressure present in the hammer return pocket 40.

What has heretofore been described as the upper composite hammer 13 consists in the main of an outer hammer section 60 and an inner hammer section 61. The inner section is threadedly engaged with the outer section and can be moved up or down, as shown in FIGURE 1, in order to change the relative position of the inner hammer section 61. On the lower side of the inner hammer section, which may be described as a platen, is located a typical die 62. A matching die 63 is mounted upon a floating die cap or lower platen 64. The workpiece 20 previously described, normally rests upon the lower die 63 after it has been heated and placed in the machine ready for a forging operation. Should the workpiece, for example, stick in the upper die 62 after forging, it can he removed by an upper knockout ram 65 acting against a knockout rod 64 which engages the workpiece. Air pressure is supplied through a knockout pressure line 67 which operates the knockout ram 65 by piston action. On the other hand, should the workpiece stick to the lower die 63 a lower knockout ram 68 acts against a lower knockout rod 69 in response to pressure in a knockout pressure line 70, substantially as described for the upper knockout mechanism. The knockout mechanism is, in any event, substantially conventional.

As a safety feature, blocks 71 on the upper composite hammer 13 are adapted to strike against complementary blocks 72 on the lower composite hammer section 14 so that, in the event the hammers should be operated without dies in place, the blocks will strike each other and absorb the blow, thereby to prevent damage to the machine in the event of such inadvertent operation.

While there has already been mention of the adjustability of the inner hammer section 61 with respect to the outer hammer 60, the machine also contemplates complete removal of the inner hammer section 61 for replacement by a special inner hammer section 73, shown in detail in FIGURE 6, upon which is mounted a yieldable rubber block 74, adapted to co-operate with a die 75 on those occasions where there may he need for forming a sheet metal workpiece '76. In this fashion, therefore, a high energy impact press can be converted into sheet metal forming where need be for making sheet metal parts of material which is very resistant to normal forming methods, or where it is desired to eliminate matched dies which are expensive.

Although sleeve valves of the general description of the sleeve valve 22 have been employed in sundry other relationships, sleeve valves heretofore have been unknown in a high energy press. Because of their size and because they must slam back and forth so rapidly, the advantages of such a valve cannot be enjoyed in a high energy press without adequate cushioning. This is accomplished in the present device by provision of a snubber cavity located above the upper end of the valve guide 23 and enclosed within a decelerator tube 81. A small orifice 82 interconnects the snubber cavit 80 with a space 83 which, incidentally, is in communication with the reservoir chamber 17. The orifice is so small that it provides a restriction without, however, completely closing ingress and egress to the snubber cavity 80. There is also a slight clearance between the cylindrical interior surface of the snubber cavity 80 and the surrounding exterior surface of the upper end of the valve guide 23.

When the sleeve valve is to be fired, as previously described, pressure is supplied through the operating fluid supply tube 19 by manipulation of the valve 27. It is important to note in this connection, that the valve 27 is entirely outside of the machine and can be located virtually anywhere on the exterior. Pressure thus exerted on the lower surface of the valve guide 23 within the operating cavity 28 drives the valve guide upwardly but it is prevented from slamming by the cushioning effect of the snubber cavity 80. In the event of there being no pressure in the operating fluid supply tube 19, pressure in the reservoir work chamber 17 would tend, because of clearances, to find its way into the snubber cavity 80 and, acting against the surface of the upper end of the valve guide 23 would tend to force the sleeve valve to closed position thereby to inhibit triggering of the machine. Any leaking of this pressure past the lower end of the valve guide 23 and into the operating cavity 28 would tend to exhaust through the exhaust tube 37.

It should be noted, incidentally, that although the pressure in the reservoir chamber 17 is from one source, and that might be a relatively high pressure, whereas the operating pressure in the operating cavity 28 may be relatively lower, because there is a larger area exposed on the lower end of the valve guide 23 than on the upper end and because this differential can be made as large as need be in favor of the area at the lower end, the operating pressure is able to overcome the pressure in the snubber cavity 80 to open the sleeve valve. After operation, however, when pressure is eliminated from the operating cavity 28 the sleeve valve tends to be closed off entirely by any pressure admitted into the snubber cavity 34) which assist in the fail-safe construction of the machine.

The sleeve valve, however, can be adjusted by external means, as for example, by employment of a crank 84. A crank shaft 85 extends downwardly into the reservoir work chamber 17 where a pinion 86 meshes with teeth on a gear wheel 87, journaled in the lower end of a sleeve 88. The inner surface of the gear wheel 87 has a threaded engagement with the decelerator tube 81 and hence, by manipulation of the crank 84, the decelerator tube can be moved up or down, thus changing the position of the 9 snubber cavity 80. By this device, therefore, the action of the sleeve valve can be limited or extended to vary its ability to pass air under pressure through the ports 26. Needless to say, although the crank shaft 85 is journaled in the plate structure 53, it is able to slide freely through the top plate 85 of the frame 10.

As a further means of controlling the operation of the machine, the high pressure supply line 16 may be divided into a first pressure supply branch 89 and a second pressure supply branch 90, controlled by a three-way valve 91. A valve 93 may also be employed in the high pressure supply line 16. The supply branch 89 may be supplied with one pressure and the supply branch 90 with another pressure. Although these can be set for use in the alternative to create either a less powerful stroke or a more powerful stroke, they can also be used in succession automatically by employment of a programmer 94. In fact, an appropriate conventional programmer may be employed operating in such fashion that any combination of strokes possible by using the

supply branches

89 and 90 either consecutively or in the alternative, can be employed so that multiple strokes in succession can be imparted to the hammers without removal of the workpiece, merely by interconnecting the programmer by conventional means to operation of the three-way valve 27 and the exhaust valve 35. Diagrammatic interconnections have been omitted in the interest of clarity.

It is important in a large machine, such as an impact press of the massive constructions necessary, that the hammers be capable of very delicate adjustment when the dies are being placed. The adjusting manipulation is frequently termed inching. Although some control, in this respect, can be exerted as previously indicated by manipulation of the hammer return pocket and the hammer shock absorber pockets. Inching can be, in the alternative, accomplished by an auxiliary control in the main exhaust passage 21. To provide the necessary structure for this, there is employed an auxiliary passage 95 in communication with the main exhaust passage 21 in which is a threeway inching valve 96. A supply pipe 97 supplies the three-way inching valve 96 and an exhaust pipe 98 leads from the valve. The supply in this instance is preferably a very low pressure supply. In this arrangement, with the exhaust valve 35 closed thereby closing the pressure chamber 18, and also incidentally with the sleeve valve 22 in closed position, the three-way inching valve 96 can be manipulated to admit air under low pressure into the pressure chamber 18 in small increments. In this way, the hammers can be gradually inched or moved by degrees toward each other, a fraction of an inch at a time, in order to properly adjust the dies 62 and 63 with relationship with each other.

The annular relationship and construction of the parts of the machine, here under consideration, makes it possible to very adequately control the environment of a space 100 which exists between the inner hammer section 61 and the lower platen or floating die cap 64. An annular seal 101, between the outer hammer section 60 and the central chamber 32 together with an annular seal 102 between the outer cylindrical surface of a cylindrical section 103 of the lower composite hammer 14 and the bore 31 on the interior of the frame 10. Still another annular seal 104, serves as a seal on the opposite side, there being additionally seals 105 and 106 at the locations indicated. An access opening 107 is provided through the cylindrical section 103 and a complementary access opening 108 is provided in the frame 10. A door 109 may be attached by bolts 110 to the exterior of the frame thereby to seal the access openings by employment of a seal 111. A pipe 112 may be provided in the door 109 so that appropriate gases, either hot or cold, and of any desired kind can be introduced into the space 100 which, in effect, comprises the platen chamber where the environment is created for the workpiece 20. In this fashion, the workpiece can be kept hot or its temperature can be varied. It can be 19 forged in a non-oxidizing atmosphere if need be, and by reason of the very fast operation of the press and even a repeated operation of the press by manipulation of the programmer 94. Repeated blows can be had upon the workpiece 20 before any appreciable change, or any undesired change occurs in the condition of the workpiece.

An operation of major importance in an impact press operating at high velocity, like that herein described, is a squeeze effect upon the workpiece 20 following an initial impact blow. The squeeze effect usually needs to be a squeeze of greater pressure than the impact pressure but may, on occasions, be a squeeze pressure of lesser amount. One way to accomplish this is to provide a squeeze chamber 115. The squeeze chamber is located between a lower inner hammer section 116 and a partition 117 extending inwardly from the lower end of the cylindrical section 103 of the lower composite hammer 14. A squeeze pressure line 118 may be connected with the squeeze chamber in order to be certain that it is sup plied with an initial desired pressure condition. A squeeze chamber control orifice 119 leads from the squeeze chamber 115 into an exhaust space 120. A flow restricting valve 121 may also be provided.

If the squeeze chamber 115 solely is relied upon for a squeeze effect, pressure will be built up in the squeeze chamber 115 as the dies strike the workpiece 20 by reason of the lower inner hammer section 116 being stopped and the partition 117 being driven upwardly by continued motion of the lower composite hammer 114. Since the volume of the squeeze chamber 115 would be then diminished, there would be an appreciable increase in pressure in the squeeze chamber which would exert a high pressure squeeze on the workpiece following impact blow;

The squeeze effect can be further modified by employment of an annular somewhat truncated powerful spring 122 of a type commonly known as a Belleville spring. Although a Belleville type spring has been suggested for inclusion, it will be understood that other types of springs are also capable of being used. When a spring is used, opposite sides of the spring initially engage opposite surfaces of the squeeze chamber as exemplified by the available surface 123 of the hammer section 116 on the top and the adjacent available surface 124 on the upper side of the partition 117. As the hammers are driven toward each other in the usual fashion, and the hammer section 116 is stopped by impact, the continued motion of the partition 117 will compress the spring 122 building up energy in the spring which thereafter will be exerted as spring pressure upon the workpiece 20 after impact. This spring actuated squeeze pressure can be in addition to the pneumatic squeeze pressure or, if desired, the squeeze chamber can be vented and spring pressure relied upon alone for squeeze pressure. The net effect of application of squeeze pressure is actually to divide the complete impact between impact pressure and squeeze pressure. Some energy is taken away from the beginning of the impact and moved toward the end of the impact so as to iron out the stroke. We have, in effect, two different masses moving together with a spring connection between them. The spring, incidentally, has to be strong so that we can accelerate the lighter mass which is the upper composite hammer to the same degree that the lower mass, namely the lower composite hammer is accelerated. The snubber and a cushioning action already described serves also in connection with the squeeze operation. Moreover, by the employment of mechanical springs like that suggested here, and particularly a Belleville type spring, where a heavy job is required multiple springs can be used whereas when a lighter job is in process, a single spring or a lighter spring can be employed, without otherwise restricting operation of the machine.

As an alternative to the squeeze operation just described, there is shown in FIGURES 7 and 8 of the drawings, another form of squeeze chamber which can make use of hydraulic squeeze pressure. In this embodiment of the device, the upper portionof the machine is the same as that described in connection with FIGURE 1 and related figures. The lower composite hammer 14 is modified to a degree, in that a platen supporting section 125 has on its lower side an annular surface 126 which lies axially spaced from and opposite an annular surface 127 on a flange 128. These two surfaces form a space between them. An annular partition 129 on an auxiliary section 130 of the lower composite hammer 14 extends into the space. An upper surface 131 of the partition 129 defines with the surface 126 a hydraulic pocket 132. The hydraulic pocket may be supplied with a pre-set oil inlet 133. An air pocket 134 has a pre-set air pressure inlet 135. An exhaust line 136 vents a pin pocket 137.

In the partition 129 is a series of circumferentially spaced pin bores 138, each containing a pin 139 slidably mounted in the respective bore. An annular ring 146 is mounted in the upper end of the air pocket 134 and the lower end of each of the pins 139 rests upon the upper face of the annular ring 140.

In operation, the hydraulic pocket 132 is prefilled with a liquid, such as oil, or water, to a nominal pressure sufficient to fill the chamber and support weight of the platen supporting section 125 together with the lower platen 64. The air pocket 134 is then filled with gas of some kind, such as air, to any desirable pre-set pressure. A typical example is one wherein the air pressure is about 1000 pounds per square inch and this pressure pushes upwardly on the annular ring 140. Since the total area of the ring, subject to air pressure, is greater than the total cross sectional area of all of the pins, the effect of the air pressure is to increase pressure on the oil in the hydraulic pocket 132, in corresponding proportion. If the difference is three to one, therefore, the oil pressure will be raised to 3000 pounds per square inch in the chosen example. Ultimately, when the mass of the platen supporting section 125 and the accompanying lower platen 64 is forced down upon impact of the hammers when they are brought together. The oil forces the pins 139 downwardly and the annular ring 140 also downwardly, which in turn compresses air in the air pocket 134, to a higher pressure proportional to the volume decrease. As the air pressure rises, it raises the oil pressure at a corresponding rate and the not total force is, therefore, increased at that rate. In the chosen example, the force could increase to something in the neighborhood of 4,500,000 pounds. Obviously, by varying the relative areas, or the pressure or volume in the air pocket 134, it would be possible to obtain a large variety of forces applied to the workpiece 20, and to predetermine a force curve optimum for any job to be done.

As has been emphasized herein, the high velocity impact press is a cylindrical press and its relatively axially moving telescoping parts create concentric axial chambers and machine parts which promote a very simple type of construction for a machine capable of such tremendous pressures as are herein involved. The annular construction of parts is very instrumental in permitting the variety of adjustment and the versatility of the force factors, return force factors, snubbing and cushioning factors, and adjustment factors which have been described in detail.

While the invention has herein been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom Within the scope of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices.

Having described the invention, what is claimed as new in support of Letters Patent is:

V 1. In a high velocity impact press for exerting controlled forces on a work piece, the combination of: a frame, a hammer supported upon said frame for axial slidable movement, said hammer including a platen supporting section and an auxiliary section movable relative to each other, said platen supporting section having axially spaced annular surfaces, an annular partition on said auxiliary section located between said surfaces, said partition having annular auxiliary surfaces defining a hydraulic pocket adjacent a platen carrying part of said platen supporting section and a pneumatic pocket on the opposite side of said partition, an annular ring in said pneumatic pocket dividing said pneumatic pocket into a hydraulic side and a pneumatic side, a plurality of circum-ferentially spaced bores through said partition between said pneumatic side and said hydraulic pocket and pins slidably mounted respectively in said bores hav ing one end of each exposed to said hydraulic pocket and the other end of each in engagement with said annular ring, said pockets being productive of a squeeze force on said platen supporting section subsequent to impact.

2. In a high velocity impact press for exerting controlled forces on a work piece, the combination of a frame, a hammer supported upon said frame for axial slidable movement, said hammer including a platen supporting section and an auxiliary section movable relative to each other, said platen supporting section having axially spaced annular interior surfaces, an annular partition on said auxiliary section located between said surfaces, said partition having annular auxiliary surfaces defining a hydraulic pocket adjacent a platen carrying part of said platen supporting section and a pneumatic pocket on the opposite side of said partition, an annular ring in said pneumatic pocket dividing said pneumatic pocket into a hydraulic side and a pneumatic side, a plurality of circumferentially spaced bores through said partition between said hydraulic side and said hydraulic pocket, and pins slidably mounted respectively in said bores having one end of each exposed to said hydraulic pocket and the other end of each in engagement with said annular ring, a source of preset hydraulic fluid in communication with said hydraulic pocket and a source of pneumatic pressure in communication with said pneumatic pocket, said pockets being productive of a squeeze force on said platen supporting section subsequent to impact.

3. In a high velocity impact press for exerting controlled forces on a workpiece the combination of a supporting frame, a pair of hammers axially slideably mounted in said frame for movement relative to each other, said frame having an axial central bore therein, one of said hammers being slideable in said bore, said one hammer having a central chamber and a platen on said one hammer in said chamber, the other hammer being slideably mounted in said chamber opposite said platen and forming a pressure chamber between itself and said one hammer, a snubber pocket complex comprising means forming a first annular substantially closed pocket of variable capacity between the interior of said one hammer and the exterior of the other hammer, means forming a second annular substantially closed multiple part pocket between said frame and said one hammer, passage means between said first and second pockets, and flow control valve means in the passage means having an unrestricted flow condition for flow from said first identified pocket to said second identified pocket and having a semi-restricted flow condition for flow in the opposite direction whereby to modify movement of said hammers relative to each other.

4. In a high velocity impact press for exerting controlled forces on a work piece the combination of a supporting frame, a pair of hammers axially slideably mounted in said frame for movement relative to each other, said frame having an axial central bore therein, one of said hammers being slideable in said bore, said one hammer having a central chamber and a platen on said one hammer in said chamber, the other hammer being slideably mounted in said chamber opposite said platen and forming a pressure chamber between itself and said one hammer, a snubber pocket complex comprising means forming a first annular substantially closed hammer return pocket of variable capacity between the interior of said one hammer and the exterior of the other hammer, means forming a second annular substantially closed multiple part shock absorbing pocket between said frame and said one hammer, passageways between said hammer return pocket and said shock absorbing pocket, and flow control means in the passage means having an unrestricted flow condition for flow from said hammer return pocket to said shock absorbing pocket and having a semi-restricted flow condition for flow in the opposite direction whereby to cushion movement of said hammers relative to each other, a return pressure compartment in the upper portion of said frame at a location above said one hammer, means forming a downwardly open snubber recess in the upper portion of said framein communication with said compartment, and an annular flange on said one hammer having a sliding fit in said snubber recess at the end of a hammer stroke of said one hammer whereby to cushion said end of the hammer stroke.

5. In a high velocity impact press for exerting controlled forces on a work piece the combination of a supporting frame, a pair of hammers axially slidably mounted in said frame for movement relative to each other, said frame having an axial central bore therein, one of said hammers being slideable in said bore, said one hammer having a central chamber and a platen on said one hammer in said chamber located on said one hammer, the other hammer being slidably mounted in said chamber opposite said platen and forming a pressure chamber between itself and said one hammer, a snubber pocket complex comprising means forming a first annular substantially closed hammer return pocket of variable capacity between the interior of said one hammer and the exterior of the other hammer, means forming a second annular substantially closed multiple part shock absorbing pocket between said frame and said one hammer, passageways between said hammer return pocket and said shock absorbing pocket, and flow control valve means in the passageways having an unrestricted fiow condition for flow from said hammer return pocket to said shock absorbing pocket and having a semi-restricted flow condition for flow in the opposite direction whereby to cushion movement of said hammers relative to each other, a pneumatic pressure charging line to one part of said multiple part shock absorbing pocket and an exhaust passage from another part of said multiple part shock absorbing pocket.

6. In a high velocity impact press for exerting controlled forces on a work piece the combination of a supporting frame, a pair of hammers axially slidably mounted in said frame for movement relative to each other, said frame having an axial bore therein, one of said hammers being slidable in said bore, said one hammer having an axial central chamber and a platen on said one hammer in said chamber, the other hammer being slideably mounted in said chamber opposite said platen and forming a pressure chamber between itself and said one hammer, a snubber pocket complex comprising means forming an annular substantially closed pneumatic hammer return pocket of variable capacity between the interior of said one hammer and the exterior of the other hammer, means forming an annular substantially closed multiple part shock absorbing pocket between said frame and said one hammer, passage means betwen said pockets, and flow contol valve means in the passage means having an unrestricted flow condition for flow from said return pocket to said shock absorbing pocket and having a semi-restricted flow condition for flow in the opposite direction whereby to cushion movement of said hammers relative to each other, a pneumatic pressure supply to one part of said multiple part shock I4 absorbing pocket and an exhaust passage from another part of said multiple part shock absorbing pocket, and means forming a secondary snubber compartment between the upper end of said frame and an upper end of said other hammer, said upper end of said hammer being axially slideable in said secondary snubber compartment.

7. In a high velocity impact press for exerting controlled forces on a work piece the combination of a supporting frame, a pair of hammers axially slidably mounted in said frame for movement relative to each other, said frame having a central bore therein, one of said hammers being slideable in said bore, said one hammer having a central chamber and a platen in said chamber located on said one hammer, the other hammer being slideably mounted in said chamber opposite said platen and forming a pressure chamber between itself and said one hammer, means forming a first annular substantially closed pocket of variable capacity between the interior of said one ham-mer and the exterior of the other hammer, means forming a second annular substantially closed multiple part pocket between said frame and said one hammer, passageways between said first and second pockets, and flow control valve means in the passageways acting in unrestricted fashion for flow from said first to .said second pockets and in semi-restricted fashion for flow in the opposite direction whereby to cushion hammer movements relative to each other, and means forming a secondary snubber compartment between the upper end of said frame and an upper end of said other hammer, said upper end of said other hammer being axially slideable in said secondary snubber compartment, a pneumatic presure supply to one part of said multiple part pocket and an exhaust passage from another part of said multiple part pocket, a return pressure compartment in the upper portion of said frame at a location above said one hammer, means forming a downwardly open snubber recess in the upper portion of said frame in communication with said return pressure compartment, and an annular flange on said one hammer having a sliding fit in said snubber recess at the end of a stroke of said one hammer whereby to cushion said end of the hammer stroke.

8. In a high velocity impact press for exerting controlled forces on a work piece the combination of a supporting frame, a pair of hammers axially slidably mounted on said frame for movement relative to each other, said frame having an axial central bore therein, one of said hammers being slidable in said bore, said one hammer having a central chamber and a platen on said one hammer in said chamber, the other hammer being slidably mounted in said chamber opposite said platen and forming a pressure chamber between itself and said one hammer, one of said hammers having an anvil at a location opposite the other hammer, said anvil having an axially movable and removable attachment to the hammer whereby to selectively shift the position of the anvil relative to both said hammers between a removed position and an extreme position of adjustment.

9. In a high velocity impact press for exerting controlled forces on a work piece the combination of a supporting frame, a pair of hammers axially slidably mounted on said frame for movement relative to each other, said frame having an axial central bore therein, one of said hammers being slidable in said bore, said one hammer having a relatively large area at one end and forming between itself and said frame a return pressure compartment, said one hammer having a central chamber and platens in said chamber located respectively on said hammers, the other hammer being slidably mounted in said central chamber and forming a pressure chamber between itself and said one hammer, a portion of said other hammer extending through said one hammer and having a relatively small area, said portion forming between itself and said frame a snubber compartment subject to the same initial pressure as said pressure return compartment, whereby a greater return stroke pressure is exerted on said one hammer than on said other hammer to effect automatic return of said hammers to initial position.

10. In a high velocity impact press for exerting controlled forces on a Work piece the combination of a supporting frame, said frame having a central bore therein, a pair of hammers axially slidably mounted for movement relative to each other, one of said hammers being slidably mounted in said bore, the other of said hammers being slidably mounted in said one hammer and forming a pressure chamber between itself and said one hammer, a reservoir work chamber carried by one of said hammers and ports between said chambers, a sleeve valve axially slidably mounted in said reservoir work chamber in operative relationship with said ports, a central operating fluid supply tube and a tubular valve guide on said sleeve valve slidably mounted on said tube, an operating cavity at one end of the valve guide and a snub'ber cavity at the other end of said valve guide, said guide having a pressure area in the operating cavity greater than the area of said guide in the snubbing cavity whereby operating pressure is adapted to shift said valve to open position against a snubbing action of said other cavity, a decelerator tube around said guide forming one wall of said snubbing cavity and a mechanical positioner on said decelerator tube extending to the exterior of said frame whereby to adjust said sleeve valve movement by change in position of said decelerator tube. 11. In a high velocity impact press for exerting controlled forces on a work piece the combination of a supporting frame, said frame having a central bore therein, a pair of hammers axially slideably mounted for movement relative to each other, one of said hammers being slideably mounted in said bore, the other of said hammers being slideably mounted in said one hammer and forming a pressure chamber between itself and said one hammer, a reservoir work chamber carried by one of said hammers and ports between said chambers, a sleeve valve axially slideably mounted in operative relationship with said ports, a central operating fluid supply tube and a tubular valve guide on said sleeve valve slideably mounted on said tube, an operating cavity at one end of said valve guide and a snubbing cavity at the other end of said valve guide, said guide having a pressure area in the operative cavity greater than the area of said guide in the snubber cavity whereby operating pressure is adapted to shift said valve to open position against a snubbing action of said snubber cavity, a decelerator tube around said guide forming one Wall of said snubber cavity, there being a clearance surrounding said guide forming a communication between said reservoir work chamber and said snubber cavity whereby to urge said sleeve valve to closed position in event of a pressure failure in said operating fluid supply tube.

12. In a high velocity impact press for exerting controlled forces on .a work piece the combination of a supporting frame, said frame having a central bore therein, a pair of hammers axially slideably mounted for movement relative to each other, one of said hammers being slideably mounted in said bore and forming a return pressure compartment between itself and said frame, the other of said hammers being slideably mounted in said one hammer and forming a pressure chamber between itself and said one hammer, a reservoir work chamber carried by one of said hammers and ports between said chambers, a sleeve valve axially slideably mounted in operative relationship with said ports, a central operating fluid supply tube and a tubular valve guide on said sleeve valve slideably mounted on said tube, an operating cavity at one end of said valve guide and a snubbing cavity at the other end of said valve guide, said guide having a pressure area in the operating cavity greater than the area of said guide in the snubbing cavity whereby operating pressure is adapted to shift said valve to open position against a snubbing action of said snubbing cavity, a decelerator tube around said guide forming one wall of said snubbing cavity, there being clearances surrounding said guide and said sleeve valve forming communications between said reservoir work chamber, said return pressure compartment and said snubber cavity whereby to urge said sleeve valve to closed position in event of a pressure failure in said operating fluid supply tube.

13. In a high velocity impact press for exerting controlled forces on a work piece the combination of a supporting frame, a pair of hammers axially slideably mounted on said frame for movement relative to each other, said frame having a central bore therein, one of said hammers being slideable in said bore, said one hammer having a central chamber and a platen on said one hammer in said chamber, the other hammer being slideably mounted in said chamber opposite said platen and forming a pressure chamber between itself and said one hammer, a reservoir work chamber on one of said hammers and operating port means between said reservoir work chamber and said pressure chamber, a control valve for said operating port means, a main exhaust valve from said pressure chamber, a supply line to said reservoir work chamber and valve means in said supply line having multiple inlet ports and an outlet port, a relatively higher pressure supply to one of said inlet ports and a relatively lower pressure supply to another of said inlet ports, and turn-on means for said valve means adapted to select one or the other of said inlet ports whereby to vary the hammer impact on successive strokes.

14. In a high velocity impact press for exerting controlled forces on a work piece the combination of a supporting frame, a pair of hammers axially slideably mounted on said frame for movement relative to each other, said frame having a central bore therein, one of said hammers being slidable in said bore, said one hammer having a cen tral chamber and a platen on said one hammer in said central chamber, the other hammer being slidably mounted in said central chamber and forming a pressure chamber between itself and said one hammer, a reservoir work chamber on said one hammer, a supply port means between said reservoir work chamber and said pressure chamber, a control valve for said supply port means, a main exhaust valve from said pressure chamber, and a supply line to said reservoir :work chamber, a three-way valve in said supply line having multiple inlet ports and an outlet port, a relatively higher pressure supply to one of said inlet ports, a relatively lower pressure supply to another inlet port and automatic programming means on said three-way valve for selectively applying said pressures in sequence to said reservoir work chamber at selected repeated intervals to vary the character of hammer impact in a continuing series of impacts.

15. In a high velocity impact press for exerting controlled forces on a work piece the combination of a supporting frame having an axial bore therein, a pair of hammers axially slidably mounted on said frame for movement relative to each other, one of said hammers being slidable in said bore, and an annular seal between said one hammer and said bore, said one hammer having an annular interior wall forming a central chamber, and an annular seal between said other hammer and said interior wall, said other hammer being slidably mounted in said central chamber and forming a pressure chamber between itself and said one hammer, a platen chamber between platen holding portions of said hammers, said frame and said other hammer having complementary radially facing access openings therethrough in communication with said platen chamber in loading position of said hammers, and a door adapted to close communication through said openings, said door having a sealed position around one of said openings whereby to isolate said platen chamber from the exterior.

16. In a high velocity impact press for exerting controlled f0rs on a. work piece the combination of a supporting frame, a pair of hammers axially slidably mounted on said frame for movement relative to each other, said frame having a central bore therein, one of said hammers being slidable in said bore, said one hammer having a central chamber and a platen in said chamber located on said one hammer, the other hammer being slidably mounted in said chamber opposite said platen and forming a pressure chamber between itself and said one hammer, a reservoir work chamber on one of said one hammers, port means between said reservoir work chamber and said pressure chamber, a control valve for said port means, a main exhaust passage having a shut off valve therein, and an auxiliary exhaust passage between said pressure chamber and atmosphere having a three-way inching valve therein, a supply passage to said inching valve of relatively small capacity and a release passage from another .port of said three-way inching valve, whereby small increments of air under pressure are introduced to the pressure chamber when the main exhaust passage is in closed position to move the hammers toward each other by small increments of limited power for initial setting purposes.

17. In a high velocity impact press for exerting controlled forces on a work piece the combination of a frame, a hammer supported upon said frame for axial slideable movement, said hammer including platen supporting and auxiliary hammer sections movable relative to each other, said platen supporting section having axially spaced annular surfaces defining an annular space, and annular partition on said auxiliary section located between said surfaces, said partition having annular auxiliary surfaces defining respectively a squeeze chamber on the side facing said platen and an exhaust space on the opposite side, an annular spring element in said squeeze pocket, one end of said spring element in initial position of said hammer being expanded under a relatively lesser pressure condition into engagement with an adjacent interior face of one of said hammer sections and the other end of said spring being in engagement with an adjacent face of the other of said hammer sections, said spring having a relatively 18 greater pressure condition and shortened length between said respective sections under impact condition of said hammer whereby mechanical squeeze pressure is applied to said platen after impact pressure.

18. In a high velocity impact press for exerting controlled forces on a work piece the combination of a frame, a hammer supported upon said frame for axial slideable movement, said hammer including platen supporting and auxiliary hammer sections movable relative to each other, said platen supporting section having axially spaced annular surfaces defining an annular space, an annular partition on said auxiliary section located between said surfaces, said partition having annular auxiliary surfaces defining respectively a squeeze chamber on the side facing said platen and an exhaust space on the opposite side, a flow restricted passage means from said squeeze chamber to said exhaust space, at least one annular substantially frusto-conical spring element in said squeeze chamber, one end of said spring in initial position of said hammer being expanded under a relatively lesser pressure condition into engagement with an adjacent interior face of one of said hammer sections and the other end of said spring being in engagement with an adjacent face of the other sections of said hammer, said spring having a relatively greater pressure condition and shortened length between said respective sections under impact condition of said hammer whereby mechanical squeeze pressure is applied to said platen after impact pressure.

References Cited by the Examiner UNITED STATES PATENTS 2,122,899 7/1938 Towler 72453 2,482,280 9/ 1949 Lerma 72-4-33 2,744,315 5/1956 Fitzgerald 72-453 3,108,506 10/1968 Murek 72453 CHARLES W. LANHAM, Primary Examiner.

H. D. HOINKES, Assistant Examiner.

Claims

1. IN A HIGH VELOCITY IMPACT PRESS FOR EXERTING CONTROLLED FORCES ON A WORK PIECE, THE COMBINATION OF: A FRAME, A HAMMER SUPPORTED UPON SAID FRAME FOR AXIAL SLIDABLE MOVEMENT, SAID HAMMER INCLUDING A PLATEN SUPPORTING SECTION AND AN AUXILIARY SECTION MOVABLE RELATIVE TO EACH OTHER, SAID PLATEN SUPPORTING SECTION HAVING AXIALLY SPACED ANNULAR SURFACES, AN ANNULAR PARTITION ON SAID AUXILIARY SECTION LOCATED BETWEEN SAID SURFACES, SAID PARTITION HAVING ANNULAR AUXILIARY SURFACES DEFINING A HYDRAULIC POCKET ADJACENT A PLATEN CARRYING PART OF SAID PLATEN SUPPORTING SECTION AND A PENUMATIC POCKET ON THE OPPOSITE SIDE OF SAID PARTITION, AN ANNULAR POCKET SAID PNEUMATIC POCKET DIVIDING SAID PNEUMATIC POCKET INTO A HYDRAULIC SIDE AND A PNEUMATIC SIDE, A PLURALITY OF CIRCUMFERENTIALLY SPACED BORES THROUGH SAID PARTITION BETWEEN SAID PNEUMATIC SIDE AND SAID HYDRAULIC POCKET AND PINS SLIDABLY MOUNTED RESPECTIVELY IN SAID BORES HAVING ONE END OF EACH EXPOSED TO SAID HYDRAULIC POCKET AND THE OTHER END OF EACH IN ENGAGEMENT WITH SAID ANNULAR RING, SAID POCKETS BEING PRODUCTIVE OF A SQUEEZE FORCE ON SAID PLATEN SUPPORTING SECTION SUBSEQUENT TO IMPACT.