US2780117A - Press for forging metal - Google Patents

Description

Feb. 5, 1957 A. F. BAUER ET AL 2,780,117

PRESS FOR FORGING METAL.

Filed Nov. 25, 1952 2 Shee'ts-Sheet l Q i Q .54

5 LJ 7A 4 76 176 '70 5 525 I E r j! I1150 I 5 I 52 6a a h; 6;

I g 54 Y 74 ed 78 INVENTOR f ,y HLFRED F. BFIUER K BY CHHRLE PACK 66 ATTORNEY 1957 A. F. BAUER ET AL 2,780,117

PRESS FOR FORGING METAL Filed NOV. 25, 1952 2 Sheets-Sheet 2 BY M ATTORN EY CHQR'LES PACK United States Patent PRESS FOR FORGING METAL Alfred Ferdinand Bauer and Charles Pack, Toledo, Ohio, assignors, by mesne assignments, to National Lead Company, New York, N. Y., a corporation of New Jersey Application November 25, 1952, Serial No. 322,456

3 Claims. (Cl. 78-41) This invention relates to presses for forging metal.

The primary object of the present invention is to generally improve the forging of metal to desired shape in separable dies. A more particular object is to provide an improved press which minimizes the hydraulic power consumption for closing the die. With this object in view I employ toggle linkage between the closing cylinder and the movable die. However, the toggle linkage is characterized by rapid motion with little force during the first part of the stroke. It develops tremendous force, theoretically approaching infinite force, as the toggle reaches its locked position, but at that time is characterized by slight movement of the die, theoretically appreaching the infinitesimal. In accordance with a feature and object of the present invention this ditficulty is overcome by forging a metal slug in a closed die cavity by means of a forging ram which is forced into the cavity after the die has been closed. To insure adequate forging pressure the forging cylinder operating on the ram may be large in diameter and subjected to great hydraulic pressure even though working a small diameter forging ram. Inasmuch as the forging stroke may be quite small, say one inch, there is economical use of hydraulic power While at the same time providing a desired wide opening of the die itself while using a closing cylinder the area of which is only a small fraction of that of the forging cylinder. Nevertheless the die is held closed despite the enormous pressure in the die cavity, because of the locked condition of the toggle linkage.

It will be noted that the present press is proportioned almost contrary to usual practice, for in the usual press there is a large diameter closing cylinder and a relative ly small diameter cylinder for transfer of metal or any purpose other than closing. In the present press the closing cylinder is small in diameter, and the forging ram is also small in diameter, but enormous forging pressure is developed by using a very large diameter forging cylinder.

Another object is to simplify the construction of the forging cylinder despite its large diameter, and with this in view the forging cylinder is an open-ended cylinder with an exposed piston. However, forcible withdrawal of the forging ram is desired for reasons explained later, and the press is accordingly provided with a separate re turn cylinder which may itself be open-ended and relatively small in diameter. In accordance with a further feature and object of the invention, a saving in axial length is attained by making the forging piston hollow, and disposing the return cylinder within the hollow piston. Differently expressed, the return cylinder is reentrantly related to the forging cylinder.

To accomplish the foregoing general objects, and other more specific objects which will hereinafter appear, the invention resides in the forging press elements, and their relation one to another, as are hereinafter more particularly described in the following specification. The specification is accompanied by the drawings, in which:

ice

Fig. 1 is a vertical section through a press embodying features of the invention, with the press shown open; and Fig. 2 is a similar view, but showing the die closed.

Referring to the drawing, and more particularly to Fig. 1, the apparatus shown comprises a. stationary platen 12 carrying a stationary die 14, and a movable platen 16 carrying a movable die 18. These dies together form a die cavity, as best shown in Fig. 2, in which the die is closed, and the lower part of which is shown at 20 in Fig. 1. The apparatus further comprises a small diameter forging ram 22 which is slidable in stationary die 14, this ram being movable into the die cavity 20. There is also a small diameter hydraulic closing cylinder 24, and toggle linkage generally designated 26 operated by cylinder 24, to move the movable die l8. The large diameter forging cylinder is shown at 28, and this drives.

a piston 30 to actuate the forging ram 22.

Considering the apparatus in somewhat greater detail, the press is preferably an upright press, the stationary platen 12 being horizontal and supported from the floor by means of appropriate supports 32. The lower end of the press maybe sunk below floor lever as shown, if it be desired to maintain the stationary platen 12 at a convenient operating elevation. A so-called crab 34 near the top of the press is fixedly spaced from stationary platen 12 by means of four main tie rods 36. The upper portions of the tie rods 36 may be threaded to receive locating nuts 38 and 40 which make possible adjustment of the elevation of the crab 34 and consequently the clearance between stationary platen 12 and movable platen 16 to accommodate the particular die being carried in the press. The movable platen 16 is slidable on the tie rods 36. The small diameter closing cylinder 24 is carried by the crab 34, and in the present drawing is shown integrally therewith, for simplicity.

Piston 42 in cylinder 24 is connected by piston rod to a crosshead 46, which in turn carries the inner ends of the spreader links 43. The outer ends of these links are connected to the toggle links and 52. Links 50 areconnected to the crab 34, and links .52 are connected to the movable platen 16.

It will be understood that when theclosing piston 42 is moved from the upper position shown in Fig. 1 to the lower position shown in Fig. 2 the toggle linkage is straightened out, as shown in Fig. 2, the crosshead 46 and spreader links 48 bringingthe toggle links 50.and 52 into alignment. i

The toggle linkage and closing cylinder arrangement are not per se new, having been used already in die castingmachines to close a die prior to the injection of molten metal. The present mechanism may follow the already established practice, and therefore has not been shown in excessive detail, For example, the links 48, 5t) and 52 may be multiple links disposed collaterally in a direction perpendicular to the drawing, or, what is equivalent, may be wide links with their ends slotted-at the pivots to receive the connecting links or the bearings. The piston rod 44 may be extended through the crosshead 46 and its lower end guided in the movableiplaten 16. The crosshead may itself be guided by a pair of slide rods disposed on either side of the crosshead toward and away from the observer in relation to the drawing.

Referring now to the lower part of the press, the forging cylinder 28 is secured to the stationary platen12 by means of tie rods. In the present case the tie rods are extensions of the tie rods 36, the latter being shouldered at 54, and the lower ends receiving nuts 56. The portions of the tie rod extensions between cylinder 28 and platen 12 receive spacers 58. These are important to take the die closing force or toggle reaction when the die is closed, but the forging ram has not yet acted orhas already been withdrawn, as shown in Fig. 2. The forging cylinder 28 is open at its upper end, and piston '30 is a hollow piston which is exposed at the top. It carries a connecting plunger 69, which in turn receives .the forging =ram.22.so.that'the .la'tteris readily removed and changed to another when changing the die. Indeed, properly speaking, the .forging ram 22 is a part of the die and re mains withit when the die is stored.

For positive return of the forging ram, despite the open-ended nature of the forging cylinder 28, the press is additionally provided with a return cylinder 62. This operates on a return piston 64, and inasmuch as they are single-acting, the cylinder. 62 is open-ended and piston 64 isexposed. Toconnectthe return piston to the ram it is provided with a crosshead 66 connected by means of vertical rods 68 to a crosshead or plate 7 at the top of forging piston 30. in practice the plate "id is secured to piston 30, but for simplicity is here shown integral.

Hydraulic fluid is supplied to forging cylinder 28 at a suitable connection 72, and to return cylinder 62 at a suitable-connection 74.

To .minimize the needed axial dimension of the cylinders at the bottom of the press the return cylinder 62 is preferably disposed within the hollow space inside the forging piston 36. Differently expressed, the return cyl- The blank is so dimensioned as to provide at least slightly more metal than is needed for a solid forging, and any excess is forced outward to form flash, indicated at 82 in Fig. 2. An overflow channel 84 (Fig. l) is preferably provided in the die to receive excess flash. The

largest diameter of the forged piece is located at the parting plane of the die, so that it is an easy matter to subsequently trim the flash from the forged piece in a simple triming die.

It will be understood that the drawing has been simplified in respect to the lower end of the press as well as the upper end of the press. For example, packing for the open-ended cylinders has been omitted, as well as means for lubrication, and for detachably securing the stops 76, etc.

While not in limitation of the invention, but by way of illustrating the contrast in relative dimension, it may be stated that in one press embodying the present invention the forging cylinder was 16" in diameter and subjected to an hydraulic pressure of twelve hundred pounds per square inch. The forging being formed was only about 2" in diameter, and the forging ram somewhat less, so'that the forging pressure developed within the die cavity was in the neighborhood of eighty thousand to one hundred thousand pounds per square inch, depending on the shape and dimension of the particular piece being forged.

In contrast with the large diameter of the forging cylinder, the closing cylinder at the top of the press was only 5 in diameter, and this incidentally was also the diameter of the return cylinder 62. Thus the upright press is made relatively stable with the large cylinder 'on bottom and the small cylinder on top, even though the top platen is the movable platen, which is convenient not only to maintain constant the operating height of the bottom die for loading slugs therein, but also in providing ejection at the top die, with consequent gravitational discharge of the forged piece.

'For this purpose the press may be provided with ejection and stripping mechanism, as disclosed in greater detail in a co-pending application Serial No. 322,404, filed on even date herewith. .Briefly, the movable die 18 is provided with a combined ejector and core 90, which is solidly backed at 92 during the forging operation. It may be moved downward by power obtained from an hydraulic cylinder indicated at 94 and connected to a gear rack 96 meshing with a long pinion 98, the other end of which meshes with rack teeth on the ejector 100 carrying the core 90.

The movable die 18 also carries a cylinder 102 connected to a slide 104 movable along rails 106. Slide EM carries a stripper plate 108 which is slotted or bifurcated at its inner end 110 so that it may be slid horizontally along the parting plane of die 18 to a position between the forged piece and the die when the forged piece has been ejected 'by ejector core 90. The latter is then pulled upward, thereby stripping the forged piece.

Slide 104- also carries arms 112 to which an inclined chute 114 is pivotally secured at 116, the lower end of the chute resting on a support roller 118 carried by the stationary platen 12. Thus the chute is moved inward to a position beneath the forged piece at the time it is stripped, thus carrying it out of the press.

The actuation of the various cylinders may be and preferably is controlled automatically, as described in the aforesaid co-pendingapplication Serial No. 322,404, filed on even date herewith. The preferred sequence of operation is to first close the die and then forge the piece. The forging ram is withdrawn before opening the die, as this helps insure retention of the forged piece in the upper die. The die is then opened; the forged piece ejected; the stripper and chute inserted; the ejector retracted; and the stripper and chute removed from their position between the dies 14 and 18, following which another slug of metal is placed in the open lower die cavity 20 preparatory to starting another forging cycle. Because of the positive actuation of the forging ram and the ejector core, substantially all of the surfaces of the forged piece may be made cylindrical, when intended to be cylindrical, instead of being given a substantial taper of, say, three to seven percent solely to facilitate separation from the die. I

The hydraulic power supply to the return cylinder 62 may be handled in either of two ways. By simply connecting the hydrauli supply permanently to theconnection 74 the return cylinder acts as an hydraulic spring and withdraws the forging ram whenever pressure is relieved from the forging cylinder 28. Thus a single valve may be used, controlling the forging cylinder. if, however, it is desired to obtain maximum possible force at the forging ram, the supply to the return cylinder 62 is preferably valved so that pressure thereon is relieved whenever pressure is applied to the forging cylinder, and vice Versa.

The slug may be a cast slug produced as set forth in a companion application Serial No. 315,128, filed Octo her in, 1952, and it may be heated to an optimum temperature for the forging operation. For example, an aluminum alloy containing some copper and silicon for strength may be heated to a temperature of from 700 to 800 F. or more narrowly, from 720 to 780 F. The slug is preferably not heated to a substantially higher tempera ture because it may be formed too easily, that is, there may be fluid components which will flow without elonga tion of the crystal structure or grain of the metal. On the other hand the slug should not be forged too cold because slight cracks or fissures may develop, with conscquent weakening of the forged piece.

The temperature, of course, depends on the particular alloy being forged.

For example, brass may be heated to a temperature of, say, 1300 to 1350" P. On the other hand certain alloys may be so plastic as to be forged without preheating, so that the slug may be placed in the cavity at room temperature.

The forging press may be used to work on any forgeable metal or alloy, although it is primarily intended for use with nornferrous metals and alloys, typically, aluminum, magnesium, brass, bronze, and zinc. The forging step may be performed either hot or cold, and any temperatures mentioned above are solely by way of example, and not in limitation of the invention.

The slug is preferably lubricated, as by daubing it with a mixture of oil and graphite just before the forging step.

Because of the relationship between the travel and the force developed by the toggle linkage, the die is preferably closed without deformation or forging of the slug. The forging step preferably is performed wholly by the forging ram. in most cases there is no difiiculty in so proportioning the diameter and length of the slug as to fit within the closed die cavity and yet provide adequate volume of metal for the finished forging (with some excess going into flash). in certain situations the die and ram design may be modified to insure this result. For example, in an extreme case in which the piece to be forged from a cylindrical slug is a cone, the forging ram may intentionally be given a diameter somewhat larger than the desired slug diameter, so that the slug is readily accommodated in the closed die by suitably adjusting the downward movement of the forging ram to make room for the slug. Of course, this expedient is not unnecessarily resorted to, in order not to unnecessarily consume hydraulic power at the forging cylinder by increasing its stroke, which usually is quite small.

However, despite the foregoing explanation it should not be thought that it is impossible to perform some deformation of the slug in the course of the die closing action. In certain cases the shape of the piece being forged may he so related to the size and shape of the slug that it is both feasible and desirable to squeeze and somewhat deform the slug during the die closing operation, and the force generated by the toggle mechanism is adequate for this, particularly so when the deformation takes place near the end only of the die closing operation. The situation then is that with the present press a slight amount of forging may be caused in the die, but in most cases, and by preference, no deformation takes place during closing of the die.

It is believed that the construction and operation of the improved press for forging metal, as well as the advantages thereof, will be apparent from the foregoing detailed description. It will also be apparent that While the press has been disclosed in a preferred form, changes may be made in the structure disclosed within the scope of the invention, as sought to be defined in the following claims.

What is claimed is:

1. A press for use with a separable metal forging die having a die cavity and a small diameter forging ram movable into the die cavity, said press comprising a sta tionary platen, tie rods extending from said platen to a crab, the portions of said tie rods at the crab being threaded to receive locating nuts to facilitate adjustment of the distance between the platen and the crab, a movable platen slidable on said tie rods, a small diameter closing cylinder carried by said crab, toggle linkage disposed between said crab and said movable platen and actuated by said closing cylinder for moving the platen, a large diameter forging cylinder disposed on the opposite side of said stationary platen, said cylinder being open at the end nearer the platen and carrying a large diameter piston for actuating the small diameter forging ram, a small diameter return cylinder open in opposite direction, a return piston in said return cylinder, and means connecting the outside end of the return piston to the outside end of the forging piston.

2. A press for use with a separable metal forging die having a die cavity and a small diameter forging ram movable into the die cavity, said press comprising a stationary platen, tie rods extending from said platen to a crab, a movable pllaten slidable on said tie rods, a small diameter closing cylinder carried by said crab, toggle linkage disposed between said crab and said movable platen and actuated by said closing cylinder for moving the platen, a large diameter forging cylinder disposed on the opposite side of said stationary platen, said cylinder being open at the end nearer the platen and carrying a large diameter piston for actuating the small diameter forging ram, a small diameter return cylinder connected to said forging cylinder, said return cylinder being disposed re-entrantly within the hollow forging piston and being open in opposite direction, a return piston in said return cylinder, and means connecting the outside end of the return piston to the outside end of the forging piston.

3. A press for use with a separable metal forging die having a die cavity and a small diameter forging nam movable into the die cavity, said press being an upright press comprising a stationary horizontal platen supported from the floor, vertical tie rods extendingupward to a crab, a movable platen slidable on said tie rods, a small diameter closing cylinder carried by said crab, toggle linkage disposed between said crab and said movable platen and actuated by said closing cylinder for moving the platen, a large diameter forging cylinder disposed beneath said stationary platen, said cylinder being open at its upper end and carrying a large diameter hollow piston for actuating the small diameter forging ram, a small diameter return cylinder connected to said forging cylinder, said return cylinder being disposed re-entrantly within the hollow forging piston and being open downwardly, a return piston in said return cylinder, and means connecting the lower end of the return piston to the upper end of the forging piston.

References Cited in the file of this patent UNITED STATES PATENTS 25,588 Sparrow Sept. 27, 1859 544,481 Coyne Feb. 11, 1896 2,185,402 Dinzl Jan. 2, 1940 2,246,414 McIntyre June 17, 1941 2,277,640 Harrington Mar. 24, 1942 2,299,105 Muir Get. 20, 1942 2,585,297 Beuscher Feb. 12, 1952 2,633,765 Glasner Apr. 7, 1953

Images