US2344743A - Forming method and apparatus - Google Patents

Description

March 21, 1944. Q H, JR 2,344,743

' FORMING METHOD AND APPARATUS I Filed May 6, 1941 3 Sheets-Sheet 1' /N VE N TOR/ HENRY COLL/ER 544/ TH, JR.

Y HA RR/J, K/ECH, F0: TER a HARR/J March 1944- H. c. SMITH, JR

FORMING METHOD AND APPARATUS Filed May 6, 1941 3 Sheets-Sheet 5 /NVENTO&/ HENRY C04 L/ER SM/ TH, JR.

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H 6 6 A &6 E w h" M E w v a m m 6 a HA RR/J K75: lllllll e FOR TH FIRM g7 TORLVE K5 Patented Mar. 21, 1944 UNITED STATES PATENT OFFICE FORMING METHOD AND APPARATUS Henry Collier Smith, In, Los Angeles, Calif. Application May a, 1941, Serial No. 392,082

21: Claims. (01. 113-44) My invention relates to procedures for forming objects such as sheet metal blanks, with special reference to deformation by application of pressure, and is directed to a novel forming method adapted to be carried out by a novel forming means.

While the principles of the invention are applicable broadly to problems of forming various types of blanks to desired configurations in various fields of industry, the invention is being initially embodied in a drawing press for shaping sheet metal parts for aircraft and the like. For the purpose of the present disclosure, I elect to describe such an embodiment of the invention, but those skilled in the art will find adequate guidance therein for applying the invention wherever it may have utility.

The general object of the invention is to pro vide an efilcient and relatively inexpensive forming apparatus that is exceptionally flexible in operation and that offers a heretofore unattainable range of deformation in one shaping procedure. My invention involves the employment of fiowable means under pressure to force a blank into intimate contact with a die or forming surface to cause the blank to take the configuration of the die. It is old in the art to provide a body of rubber or other deformable material in a confined space, to place a blank against the deformable body, and to advance a forming die against the blank into the confined space for the purpose of placing the deformable body under su1'-,

ficient pressure to force the blank into intimate contact with the forming die. While this older practice has utility and can meet certain forming tasks satisfactorily, it does have definite limitations and inherent disadvantages that curtail its range of usefulness. It is an object of the .present invention to provide a novel procedure that is largely free of such limitations and consequently is more efflcient and has a wider range of application.

Some of the limitations and disadvantages of the older practice mentioned above are attributable to the fact that the deformable means employed in the older combination is a coherent body nitude of pressure. The fact that a coherent body is employed also makes it impossible to vary the mass of the fiowable material in the confined space in the course oi a forming procedure. As for the engendering of pressure solely through the medium of the die, the fact that the pressure is a function of the die movement more often than not precludes the attainment of an optimum pressure at a desired stage in a die movement and only rarely permits the application of optimum pressures at two diil'erent stages of the die movement.

In contrast, an object of my invention is to provide in such a combination a flowable means of substantially perfect fluidity for efflcient pressure distribution in all directions, and a further object is to provide for close control of the pressure of the fiowable means in completeindependence of die movement, in complete independence of changes in the effective volume of the confined space, and without the necessity of uncovering the confined space or even interrupting an operation cycle. It is my purpose to provide sufliciently close control of both the die movement and the forming pressure to attain exceptional flexibility in the sense of adaptability to a wide range of divergent forming procedures. The end sought is to permit the die maker and the press operator to seek an ideal forming procedure for a given task without compromising to any material degree because of the limitations of the available apparatus.

One of the objects of my invention is to provide for intermittently progressive formation of that is fluid in character only to a limited degree, and other shortcomings are attributable to the fact that pressure in the deformable body is derived solely from the die and is therefore dependent upon movement of the die. The imperfect fluidity of the deformable body prevents uniform distribution of the engendered pressure in all directions and precludes close, control of the pressure or even ascertainment of the maga blank with one set-up of the apparatus and in a single cycle of operations on the part of the apparatus. I propose to shape a blank by definite stages through a progressive series of configurations to a final predetermined configuration without changing dies and without losing time between stages in the forming cycle. By resorting to stepby-step shaping to avoid overstressing the mat'erial being shaped, I attain an exceptional range of deformation without breakage, and by covering the successive stages in a single cycle or Operations I achieve new production economies. In this regard an object in mind is to provid for alternate forming operations in such a cycle, for example, forming pressure on one portion of a blank alternating with forming pressure on another portion of the blank or, for another example, a drawing operation alternating with a straightening or flattening operation.

A further object of the invention relates to the attainment of exceptionally deep draws by a male die. I propose to press the sheet material against the advancin male die with such high pressure and such uniformly distributed pressure: 'as to make the progressively contacting portion of the sheet in 'eifect integral with .the die. thereby avoiding slippage relative to the die with consequent stretching and rupture 'of the sheet material. For the attainment of deep drawing. I tur ther propose to provide for intermittently pressing out wrinkles and ridges in the undrawn por tions of the sheet material.

Broadly described, the invention is characterized by the combination of means providing a forming surface and flowable means including a body of fluid to press a blank into intimate contact with the forming surface. The preferred form of the invention is characterized by the concept of employing a flexible wall or diaphra m of flowable material for the purpose of separating the fluid from the blank and for the purpose of transmitting pressure from the fluid bod to the blank.

One object of the invention is to provide flexible control means for closely regulating the pressure of the fluid body preferably in cooperation with similar means for varying the configur ion of, the forming surface. In one practice of the invention it is contem lated that the configuration cf the forming-surface will be variably controlled by pressure opposing the pressure of the fluid body, and it is proposed to control the forming operation by varying the relative values of these two pressures. Thus it is contemplated that an intermittently progressive forming operas tion may be caused by fluctuating either the die pressure or the opposed pressure of the fluid body. With reference 'to control, a further obliect of the invention is to provide an arrangement that is peculiarly suited for automatic operation throughout a forming cycle.

Certain practices of the invention include the employment of a floating forming member interposed between the blank and the diaphragm that bounds the fluid body, and certain objects of the invention, which will be understood later, relate to the design and function of such a floating member.

A still further object of the invention. is to provide a structure with independently movable telescoped outer and inner rams without any gaps in effective cross-sectional areas.

Other objects and advantages of my invention will be apparent in the more detailed description to follow, taken with the accompanying drawings.

In the drawings. which are to be taken as illustrative only:

Figs. 1 to 7 are diagrammatic views representing successive stages in a forming procedure that may be followed in the practice of my invention;

Figs. 8 and 9 are diagrammatic views representing two stages in a second forming procedure that may be followed;

Figs. 10 and 11 are diagrammatic views reprepractice of the invention;

Fig. 16 is a section taken as indicated by the irregular line |3|8 of Fig. 15: and

Fig. 17 is a simplifled verticaltsection of the apparatus combined with a diagram of a fluid-control system for the apparatus.

Fig. 1 represents an apparatus comprising an upper assembly generally designated 20 and a lower assembly generally designated 2| which are adapted to be brought together as shown in Fig. 2

to form a closed space or chamber 22. It is contemplated that one of the two assemblies 20 and 2| will present forming surfaces on one side of a blank 23 and that the other assembly will harbor a fluid body on the other side of the blank. In the particular. arrangement shown, the upper assembly includes an inner forming member 25 and an outer forming member 26 that cooperate in defining a forming configuration. at least one of the two forming members being movable to permit the operator to vary the forming configuration. The inner forming member 25 which may be termed the inner die has, for example, a forming recess 21 and a cutting recess 28 while the outer forming member which may be termed the outer die has a flat forming face 30 that is annular in plan.

The lower assembly 2| may include the following elements: an open top fluid receptacle 3| having a fluid passage 32; a fluid body 33 in the receptacle, which fluid body may be either gaseous or liquid, but in the preferred form of my invention is a body of oil; a suitable diaphragm 35 spanning the fluid receptacle, which diaphragm may comprise a sheet of rubber or like material; a clamping ring 35 engaging the'margin of the diaphragm; and a guide ring 31 that is in effect an extension of the receptacle 3|.

In the particular practice of the invention representedby Figs. 1-7, a third forming member 38, which may be termed a floating forming member or floating die, rests upon the diaphragm 35 within the guide ring 31. This floating forming member 38 may be in the form of a ring of tapered cross-sectional configuration as indicated in the drawings.

In preparation for the forming procedure represented by Figs. 1 to 7, the upper and lower assemblies 20 and 2| are spaced apart for access to the chamber 22, and the blank 23 that is to be processed is placed in the chamber on top of the floating die 38. The body of oil 33 is, of course, at substantially atmospheric pressure and may be at a relatively low level.

The next step is to bring the two assemblies 20 and 2| together to completely enclose the blank 23 as shown in Fig. 2. While the two assemblies 20 and 2| are being brought together, the inner die 25 may be maintained at a constant spatial relationship to the outer die 26 to deflne a desired initial configuration for the blank 23. In the preferred practice of my invention, however, the two dies 25 and 26 of the upper assembly are independently movable toward the lower assembly. Figs. 1 and 2 indicate the movement of the outer die 26 against the lower assembly 2| to close the chamber 22, and Figs. 2 and 3 represent subsequent movement of the inner die 25 downward to the position relative to the outer die that corresponds to the desired configuration for the blank. In the particular procedure being described, it is contemplated that the blank 23 will be drawn progressively by stages, and to define an initial configuration for the blank the inner die 25 is initially extended below the outer die the fluid body inthe chamber 3| is placed under pressure to cause the diaphragm 33 to press upward against the central portion of the blank 23 and against the floating die 38. The upward pressure of the diaphragm 35 forces the Tcentral areas of the blank to conform to the configurathe blank 'i'rom creeping or stretching, I substantially avoid any tendency of the material or the blank to rupture at the leading edges or along the sides of the inner die 23. By this procedure I i am enabled to make deeper-draws than possible by any prevalent commercial practice. One feature to be noted here is. that the diaphragm 33 tion of the inner die 25, one portion of the blank I being forced into the forming recess 21 and a minor portion of the blank being forced into the cutting recess 28. It will be noted that the edges of the forming recess 21 are not sufllciently abrupt or sharp to sever the blank but that the walls of the cutting recess 28 are substantially vertical to form edges suiflciently abrupt to cause rupture of the blank. As indicated in Fig. 4 the diaphragm drives a severed portion 33 01' the blank against the inner end of the recess.

The upward pressure of the diaphragm 35 also acts against the floating die 38 to drive the floating die upward around the inner die 21 toward the forming surface 30 of the stationary die 26.

In the particular arrangement indicated by Figs. 1 to 'l the forming die 38 is complementary to the inner die 25 with sufllcient clearance to allow for the thickness of the blank 23 and upward movement of the floating die draws the material of the blank by forcing the blank around the exposed portion of the inner die 25. The drawing action of the floating die 38 forms a marginal flange 40 on the blank 23 and the floating die comes to rest against the flange 40 with sufflcient pressure to iron out any wrinkles or ridges that may be formed in the marginal flange by the flange 43 disappears after the flrst stage, but any drawing operation. It is contemplated that the pressure to which the fluid body 33 will be subjected willsufllce for whatever'function ,inironing out the flange of the blank is required on the part of the floating die 38. Inone practice of the invention, about 2000 lbs. per sq. in. will be employed to form metal blanks of 16 gaugejthiek- 1 ness or thicker. In another practice of the inven tion it may be desirable todevelop 5000 lbs. pres{ sure per square inch or more.

After the blank is formed to what may be termed theinitial configuration shown inFig. 4 the pressure and volume of the fluid body 33 are reduced to permit the diaphragm 35 to withdraw to a material extent, asindicated in Fig. 5. The operator 'then advances the inner die 25 into the chamber 22 to extend the exposed surface of the inner die, as indicated in Fig. 6. The volume and is formed or molded with annular corrugations 4i to favor extensive axial flexure for deep draws.

In the procedure illustrated by Figs. 1 to '7 the metal is formed in two stages to the final conflguration shown in Fig." 7, and the marginalnumber of intermediate configurations may be contemplated with the floating die 33 functioning to flatten out the marginal flange after each drawing operation. As will be explained later. provision is made for controlling the inner die 25 and for controlling the pressure and volume of the fluid body 33 without the necessity of opening the chamber 22 so that the described cycle of forming operations may be performed expeditiously by simply manipulating two controls.

Figs. 8 and 9 illustrate a forming procedure that is carried out by the same apparatus with an inner die 42 substituted for the previously described inner die 23. In this second procedure. Fig. 8 corresponds to Fig. 4 and the previously described steps are carried out up to this point of forming a blank 43 to an initial configuration. In this second procedure, however, the remaining steps to shape the blank to a flnal configuration shown in Fig. 9 are carried out without wholly releasing the fluid body 33 from pressure. It is contemplated that the inner die 42 will be progressively advanced, either continuously or intermittently from the position of Fig. 8 to the position of Fig. 9, and that pressure in the fluid body 33 will be maintained to cause the blank 43 to change progressively in configuration in accord with the advance of the inner die. To carry out this procedure, it is merely necessary to have the operating pressure efl'ective on the inner die 42 predominate over the opposing pressure exerted by the fluid body 33.

'In another practice of the invention illustrated by Figs. 10 and 11, a floating member 43 may be employed that is of substantially the same shape as the previously described floating die 38 and. in like manner, rests on the diaphragm 35. The

' ing member 43 on top of the diaphragm 35, as

. with sufllcient force toffreezei the material of the blank to the inner die. Inother words, it is. contemplated that the pressure exerted by, the diaphrag-m willbausei the rnetal' of the blank 23 to act as arr-integral part jlo! the inner Jdi'e, there by preventingrelativefmovementbetween the surface of the inner die-sand thesurrounding ma-f terial of the b1ank;jf; Byemploying high fluid pressure in this manner-to prevent the" material jet indicated in Fig. 10, and then pressure is applied to the fluid body 33 to cause the diaphragm to carry the blank upward into intimate pressural contact with the inner die 41'.

In some practices of my invention, especially practices involving only relatively shallow draws, no floating. die will be employed to cooperate with the diaphragm 33 Fig. 12, for'example,

shows the previously described apparatus without any floating die, the apparatus being set up with'aplain cylindrical inner die 43 to form a blank 30 to theconflguration of a shallow flanged In this practice, the blank is placed on ,thediaphragm and then pressure is applied to the diaphragm to cause the blank to envelop the exposed portion'of the inner die 48. It will be noted that aflmarginal portion 5! of theblank is forced by the diaphragm against the flat forming surface 86 of the'outer die 26.

Among the innumerable forming procedures contemplated in the various practices of my invention is a forming method exemplified by Figs. 13 md 14. The setup, of the apparatus is the same as in Fig. 12 except that an inner die 62 is substituted for the inner die 48. The forming surface of the inner die 62 is restricted to a cylindrical surface 62 presented by an L-shaped or angular extension 66 of the inner die. The object in mind here is to form a blank 66 to a tubular configuration represented by the cylindrical surface 68. In carrying out this procedure, the blank 66 is placed on the diaphragm 86 as shown in Fig. 13 and then the volume and pres-- sure of the fluid body 33 are increased to cause the diaphragm to completely envelop the blank and the die extension 66. The blank is wrapped around the'die. extension-66: into. the form of a tube, which tube is subsequently removed from 68 extending upward from the base and a stationary crown generally designated 66 supported by the tension rods. The previously mentioned lower assembly 2I is stationary on the base 51 while the previously mentioned outer die 26 of theupper assembly 26 is connected with what may be termed an outer ram 6i, and the inner die 26 of the upper assembly is carried by an inner ram 62, the two rams being movably supported from the crown 66. The outer ram BI is forced downward by fluid pressure in an annular hydraulic chamber 68 which may be conveniently termed the outer ram lowering chamber and is retracted upward by hydraulic pressure in a pair of auxiliary lift cylinders 65. For urging the inner die 26 downward, an inner ram lowering chamber 66 is provided within the stationary crown 66, and to raise the inner die a small inner ram lift chamber 61 is provided inside the inner ram 62. It will .be apparent at this point that convenient control means including suitable control valves may be utilized to re-,- ciprocate the inner and outer dies 25 and 26 and to raise and lower the fluid pressure under the diaphragm 35. The structure of the selected embodiment of the invention will now be described in more specific detail.

The base 51 comprises a bed plate 68 unitary with a cylindrical pedestal l6. Resting on the bed plate 68 is the lower assembly 2| which ineludes: the fluid receptacle 8i containing the body of oil 83 and having the previously mentioned passage 82 for communication with the body of oil the diaphragm 35 spanning the receptacle; the clamping ring 86 removably bolted to the receptacle; the guidering l1 resting on the clamping rim; and the floating die 38 resting on the diaphragm inside the guide ring. When set up for use, the lower assembly 2| is immobilized by suitable bolts II extending downward into the bed plate 66 from peripheral lugs 12- on the guide ring 81. For convenience inhandiing, both the fluid receptacle 8| and the guide ring 31 may have peripheral knobs or handles I8.

Each of the tenslon'rods 68 is provided at its opposite ends with reduced portions 16 carrying large retaining nuts I6. The lower ends of the tension rods seat in complementary bores in the bed plate 68 while the upper ends seat in complementary bores in a relatively thick web 11 of the crown 66.

The crown 66 of the press includes the following principal parts: an outer cylinder 86 that is unitary with the web 11 and that slidingly embraces the outer ram 6| an inner cylinder 8i that slldingly embraces. the inner ram 62 and has a' radial wall 62, the wall 82 being anchored to the upper end of the outer cylinder by nuts 63 on studs 86: and a cap 86 closing the top of the inner cylinder 8! and secured thereto by nuts 61 on studs 88. v i

The outer ram 6I has a cylindrical wall 86 for sliding contact with the outer cylinder 86 and has-an-. inner radial wall 8| that slidingly embraces the inner ram 62. The walls 86 and 8| of the outer ram 6i cooperate with the outer and inner cylinders 86 and 8| and the inner ram 62 to form the previously mentioned outer ram lowerin chamber 63. .It will be noted that this chamber 68 includes space within the crown 66 above the outer ram as well as space within the outer ram below the crown and that the cylindrical wall 860! the outer ram provides ample clearance 62 around the inner cylinder 8| for free fluid flow between these two spaces. To minimize leakage from the hydraulic chamber 68, the lower end of the outer cylinder 86 and the lower end of the outer ram 6| may each be recessed to receive suitable annular packing 93 retained by a removable metal packing ring 65. Fluid communication with the outer ram lowering chamber 68 is provided by a passage 96 formed by suitable bores in the radial wall 62 at the top of the chamber.

Suitably-attached to the lower end of the outer ram 6| is what may be termed a lift ring 91 having two opposite lift arms that are attached by nuts I66 tocorresponding lift rods I6I, the lift rods being in turn connected with lift pistons I62 in the previously mentioned lift cylinders 65. Each of the lift cylinders 65, which may be attached to the crown 66 of the press by suitable bolts I68, is provided with a cap I having a vent opening I66, and each cylinder has a lower end wall M1 on which is mounted a suitable packing gland I66 surrounding the corresponding lift rod I6I. In the course of operation, fluid flows into and out of the lift cylinders 65 through suitable ports 6 near the lower ends of the cylinders.

Suitably connected with the outer ram 6|, for example, by attachment to the lift ring 911s a cylindrical extension, to the lower end of which is bolted the previously'mentioned forming die 26. The cylindrical extension III may have vertical slots or windows II2 through which the movements of the inner forming die 25 may be observed. In the preferred form of my invention I provide suitable index means, such as index marks II3, on either the inner forming die or the inner ram to be read with reference to the lower end of one of the windows H2 for ascertaining the position of the inner forming die relative to the outer forming die.

The outer forming die may comprise an outer frusto-conical steel shell H5 and an inner body II6 of some suitable alloy cast into the shell, the shell having inner ribs or flanges I I! to make the cast body unitary with the shell. Such an inner body formed or low melting material may be readily cast to a desired forming configuration and may be melted for recasting whenever a design is changed or abandoned.

It is essential that the upper assembly 20 be held immovable against the lower assembly 2I during an operating cycle, especially if high fluid pressure is developed in the lower assembly. Any liquid that might be employed for exerting pressure in the outer ram lowering chamber 63 will be found to be slightly compressible at exceedingly high pressures and such contraction in the volume or the hydraulic fluid may permit the outer die 28 to retract upwardly from the guide ring 31 to a slight extent. Toprevent any upward retreat of the outer forming die, I may of course employ some positive mechanical means instead or hydraulic means for the actuation of the outer ram 6|, but I prefer to use the hydraulic arrangement shown and to employ a suitable lock or hold-down device whenever exceedingly high pressures are employed.

Such a hold-down device may comprise one or more spacer members adapted for removable insertion between the crown 60 oi! the press and the lift ring 81 of the outer ram assembly when the outer ram is at its lower limit position. It is contemplated that two such spacers will be provided within convenient reach of the operator from the front. As best shown in Fig. 15. each of these spacers may be in the form 01' an inclined bar I20 having a handle I2I, each or the bars being unitary with a pair of spaced rings I22 rotatably embracing one of the tension rods 58. The operator rotates the inclined bars I20 into and out of effective positions about the axes o1 the corresponding tension rods 58. When a bar I20 is swung outward to its ineflective position, it is supported by a collar I 23-fixedly embracing the tension rod 58.

The inner ram 62 is in the form of a closed cylinder, at the lower end of which is a tapered transverse recess I25 for dovetail engagement with a complementary upward projection I26 of the inner forming die 25. After the projection I28 01' the inner forming die is inserted in the recess I25 of the inner ram, a keeper or spacer bar I21 is inserted in the recess to make the inner forming die rigid relative to the inner ram. For occasional access to the interior or the inner ram from below, the inner ram may be provided with a bottom port I28 communicating with the recess I25, the port being normally closed with a removable plug I30.

It will be noted in Fig. 15 that the inner ram lowering chamber 66 is defined by the inner ram 62, the surrounding inner cylinder 8I of the crown 60, and the crown cap 86. In the course of operation fluid flows into and out of the chamber 66 through a suitable passage I3I bored in the radial wall 82 at the top oi! the inner cylinder 8I. prevent leakage between the inner ram lowering chamber 66 and the outer ram lowering chamber 68, I may provide packing assembly comprising a lower metal ri I32 secured to the upper end of the inner ram 62, annular packing material I33,- and an upper removable metal ring I35. Also mounted on the upper end of the inner ram 62 is a bushing I36 carrying a packing gland I31 that slidingly embraces a fixed tube I40.

The fixed tube I40 ispart of structure that may be provided to raise the inner ram, which structure will now be described. The fixed tube I40 i mounted in and extends through a bushing HI in the crown cap 83, and carries at its upper end a hollow fitting I 42 having a lateral passage I43 tor flow or fluid into and out of the fixed tube. On the lower end or the flxed tube I40 inside the inner ram 82 is mounted a fixed piston I45 that is slldingly embraced by a movable cylinder I46 depending from the upper end of the inner ram. In the particular construction shown, the movable cylinder I46 is threaded onto the lower end of the bushing I36. A suitable vent tube I41 substantially longer than the fixed tube I40 extends upwardly axially through the fixed piston I 45, the .iixed tube I40, and a packing gland I48 0n the top of the fitting I42 to provide communication between the atmosphere andthe interior of the inner ram below the fixed piston I45. It will be noted that the inner ram lifting chamber 61 is defined by the fixed piston I45, the movable cylinder I46, and -the bushing I36 at the top of the inner ram, and it will be further noted that the fixed tube I40 is apertured to provide one or more ports I50 for fluid flow into and out of the chamber 61.

The novel relationship in the arrangement of the outer and inner cyhnders and 8|, and the outer and inner rams 6I and 62 is to be noted. The cross-sectional areas or the two rams are complementary with no intermediate gap. Only three annular seals are required: one between the inner ram and outer ram; one between the inner ram and inner cylinder; and one between the outer ram and outer cylinder.

Fig. 1'7 is a simplified vertical section of the same press combined with a diagram of a hydraulic arrangement that may be employed for operating the press in one practice of the invention. A low pressure reservoir I55 for the oil or other hydraulic liquid is connected to a suitable pump I56 that supplies a high pressure tank I51, an adjustable relief valve I58 in a by-pass I60 being provided to set the maximum pressure for the tank I51. A high pressure supply pipe I6I from the high pressure tank I51 branches to various parts or the system.

One branch I62 from the high pressure ipe I6I extends to the fluid passage 32 o! the receptacle 3I and has a three-way control valve I63. In one extreme position of the valve I63, the high pressure tank I51 is placed in direct communication with the receptacle 3|; in the other limit position of the valve the receptacle 3I is placed in communication with a branch I65 of a return flow pipe I66 to the low pressure reservoir I55; and at an intermediate position of the valve the receptacle 3I is cut on from both-the high pressure pipe and the low pressure pipe. To set the maximum pressure for the fluid body 33 in the receptacle 3|, which pressure may be substantially below the pressure in the tank-I51, an adjustable relief valve or pressure regulator valve I61may be provided in a by-pass I58 from the receptacle 3| around the control valve I63 to the return flow pipe I65.

A pipe I10 branching from the high pressure pipe I6I to the fluid passage 36 for the outer ram lowering chamber 63 is provided with a threeway control valve "I. At one limit position of the valve I1I liquid is permitted to flow from the high pressure tank I51 to the press chamber 63' to lower the outer ram 6|. At the opposite limit position of the valve, liquid is released from the chamber 63 through the valve to a branch I12 of the return flow pipe I66. At an intermediate position of the valve th press chamber 63 is cut oil from both the low pressure reservoir I55 and the high pressure tank I51.

To provide for lifting the outer ram 8|, the high pressure pipe I6I leads through a three-way valve I13 to a pipe I15 that has one branch I16 to the fluid port IIO'of one of the lift cylinders 65 and a second branch I11 to the corresponding port of the other lift cylinder 65. The three-way valve-I13 likewise is movable to three positions, a position 'for delivering high pressure liquid to the two lift cylinders, a position for releasing liquid from the two lift cylinders to a branch I18 of the return flow pipe I66, and an intermediate position cutting ofl both lift cylinders from the rest of the system.

In the preferred practice of my invention the two three-way valves HI and I13 associated with movements of the outer ram 6! are operatively connected to a manually operable control member or handle I80, the operative connections being indicated by dotted lines I8I. In the contemplated arrangement, both the valves HI and I13 are at their intermediate positions when the control member I80 is at an intermediate position, and movement of the control member in either direction from its intermediate position causes one of the valves HI and I13 to establish communication between the high pressure tank I51 in the press while causing the other valve to establish communication between the press and the low pressure reservoir I55. It is apparent that the outer ram will become stationary whenever the control member I80 is at its intermediate or 'neutra.l position. Movement of the control member I80 from its neutral position to one of its limit positions will permit liquid to flow from the high pressure tank I51 to the outer ram lowering chamber 63 and simultaneously permit liquid to flow from the two lift cylinders 65 to the low pressure reservoir I55. Movement of the control member I80 from its neutral position to its alternate limit position will permit liquid to flow from the high pressure tank I51 to the ports III) of the lift cylinders 65 and simultaneously permit liquid to flow from the press chamber 63 to the low pressure reservoir I55. Upward movement of the two lift pistons I02 displaces air out of the lift cylinders through the vent openings I06.

A similar valve arrangement for controlling movement of the inner ram 62 includes a threeway valve I82 for lowering the inner ram, a threeway valve I83 for raising the inner ram, and a manually operable control member I85 common to the two valves and operatively connected therewith, as indicated by dotted lines I86. The three-way valve I82 is in a branch I81 of the high pressure pipe I6I that leads to the fluid passage I3I at the upper end of the press chamber 66 and a branch I88 of the return flow pipe I66 is connected to the valve for release of fluid from the press chamber 66. The three-way valve I83 is in a branch I90 from the high pressure pipe I6I that leads to the fluid port I43 at the top of the fixed tube. At the high pressure position of the valve I83, the liquid under high pressure passes down the fixed tube I40 and flows through the ports I50 into the press chamber 61 for lifting the inner ram. When the valve I83 is moved to its opposite position, liquid is released from the press chamber 61 through the pipe I90 to a branch I9I of the return flow pipe I66. Movement of the control member in one direction from its neutral position will cause the inner ram 62 to rise, and movement in the opposite direction will cause the inner ram to descend, the inner ram remaining stationary whenever the control member is in the neutral position.

In one practice of my invention, I provide adjustable means for individually limiting the pressures delivered to the press by each of the three-way control valves I1I, I13, I82, and I83. Such limiting or regulating means may comprise suitable adjustable relief valves or pressure regulator valves in bypasses across the three-way valves. Thus, in Fig. 17 I show a relief valve I92 in a by-pass I93 across the three-way valve ill, a relief valve I95 in a by-pass I96 across the three-way valve I13, a. relief valve I91 in a bypass I98 across the three-way valve I82, and a relief valve 200 in a by-pass 20I across the threeway valve I83.

The capability of the described apparatus to carry out the various forming procedures exemplified by Figs. 1 to 14 is apparent from the foregoing description.

Starting with the apparatus in the disposition corresponding to Fig. l, for example, the operator manipulates the control I to lower the outer ram 6i thereby closing down the outer forming die 26 against the guide ring 31 of the lower assembly 2I. At the end of this step the disposition of the apparatus corresponds to Fig. 2, and the operator then manipulates the control I to lower the inner ram 62 to extend the inner forming die 25 below the outer forming die 26 to the degree shown in Fig. 3, the operator being guided in this manpulation by the index scale I I3. With the two upper dies thus disposed to define the initial drawing configuration of the blank, the operator turns the valve I63 to send high pressure liquid into the receptacle 3I to cause the diaphragm to press the blank upward as indicated in Fig. 4.

To carry out as many additional drawing stages as may be required, the operator watches the index scale H3 and alternately manipulates the control I86 with one hand and the valve I63 with the other hand. The succeeding drawing operations in the cycle follow each o er with so little loss of time that very little of the heat engendered in the blank by one drawing operation is lost before the succeeding drawing operation. Since the metal of the blank remains heated throughout the operating cycle, relatively deep draws may be made without rupture, and there is no necessity for annealing the metal between the succeeding drawing operations.

In one procedure exemplified by Figs. 8 and 9, the liquid pressure upward against the diaphragm 35 is maintained at an effective value throughout the drawing procedure, the inner die being advanced in opposition to such pressure. One manner of carrying out such a procedure involves adjusting the maximum liquid pressure for lowering the inner ram 62 at a sufficiently high value relative to the maximum pressure in the receptacle 3| to cause the inner ram to advance in opposition to the diaphragm pressure. In adjusting the pressure regulating valves for such operation, relative areas affected by the fluid pressure must of course be taken into consideration. The operator first advances the inner .die 42 to the position shown in Fig. 8 and then raises the fluid pressure under the diaphragm to maximum to give the blank an initial configuration. While the inner die is stationary, the operator then raises the liquid pressure in the press chamber 66 without lowering the pressure under blank; applying fiuid pressure to said fiowable means to press the blank against said forming fluctuating one of these pressures to cause the inner die to inch" downward in opposition to pressure from the diaphragm. To carry out this procedure the regulating valves are so adjusted that when the pressure in the press chamber 66 and the pressure in the receptacle 3| are at normal effective values, the tendency of the ram to descend is balanced by opposition from the diaphragm. When such balance of pressure exists, the inner ram is held stationary. The inner ram may be inched downward either by intermittently raising the pressure in the chamber 88 above the normal balancing pressure or by intermittently lowering the pressure in the receptacle 3| below the normal balancing pressure. In my preferred practice I simply oscillate the valve I83 to cause the liquid pressure under the diaphragm to fluctuate and thereby permit the inner die to inch downward with each fluctuation of pressure. In this procedure the transition from the blank configuration of Fig. 8 to the blank configuration of Fig. 9 may be made in relatively small increments in close succession. The oscillation of the valve I63 may be relatively slight to cause only slight drop in the pressure under the diaphragm or may be extreme to drop the receptacle pressure to minimum, but if the valve IE3 is swung to its extreme release position, it must be quickly returned to its pressure applying position to prevent too great an advance of the inner die in one step.

The various operating procedures and a preferred form of my apparatus set forth herein in specific detail for the purpose of illustration and to disclose the principles involved will suggest to those skilled in this art various changes and substitutions that do not depart from the underlying inventive concept; I reserve the right to all such modifications and substitutions that come within the scope of my appended claims.

I claim as my invention:

1. A method of forming a blank to a predetermined configuration including the steps of: providing walls including a forming wall defining a confined space; placing said blank in said confined space with one side of the blank against said forming wall; providing fiowable means including a body of fluid in said space on the other side of said blank; applying pressure to said body of fluid to press the blank against said forming wall; shifting at least a portion of said-forming wall inward toward said blank to provide a new forming configuration; reducing the volume of said fluid body to permit the blank to retreat to accommodate said shift; and applying pressure to the body of fluid to press the blank against said forming wall after the shift.

2. A method of forming a blank to a predetermined configuration including the steps of: providing walls including a movable forming wall defining a confined space; placing said blank in said confined space with one side of the blank facing said forming wall; providing fiowable means in said space on the other side of said wall; applying inwardly directed pressure to said forming wall to resist the outward pressure of said fiowable means; and fluctuating one of said pressures to vary the relative magnitudes of said inward and outward pressures thereby to cause said forming wall to move intermittently to progressively approach a position corresponding to said predetermined configuration.

3. A method of forming a blank to a predetermined configuration including the steps of: providing walls defining a confined space including a movable forming wall and a stationary forming wall; adjusting said'movable forming wall relative to said stationary forming wall to correspond to an initial forming configuration differing from said predetermined configuration; placing said blank in said space with one side of the blank facing said two forming walls; providing fiowable means in said space on the. other side of said blank; applying fluid pressure to said fiowable means to press th blank against said two forming walls; applying inwardly directed pressure to said movable forming wall to substantially balance the outward pressure of said flowable means; and fluctuating one of said pressures to intermittently unbalance said pressures in a direction to cause said movable forming wall to shift progressively to a position relative to said stationary forming wall corresponding to said predetermined configuration.

4. A method of forming a blank to a predetermined configuration including the steps of: providing walls defining a confined space including two contiguous forming wall members corresponding to contiguous portions of said predetermined configuration; adjusting said two forming walls relative to each other to correspond to an initial forming configuration differing from said predetermined configuration; placing said blank in said space with one side of the blank facing said two forming walls; providing fiowable means in said space on the other side of said blank; providing a fioating forming wall complenrentary to one of said two forming walls intermediate said blank and said fiowable means; applying fiuid pressure to said fiowable means to press against the blank and against said-floating forming wall to force the blank into intimate contact with said two forming walls thereby to shape the blank to said initial configuration; applying inwardly directed pressure to at least one of said two forming walls to resist the outward pressure of said fiowable means; and fluctuating one of said pressures to cause relative movement of one of said two forming walls to cause the two forming walls to progress intermittently to relative positions corresponding to said predetermined configuration thereby to change the shape of the blank progressively to said predetermined configurationl 5. An apparatus for forming a blank to a predetermined oonflguration, including: means presenting a forming surface to one side .of the blank; a flexible sheet having one face directed toward the other side of the blank, said sheet being formed with a series of annular corrugations of progressively increasing diameter; a body of fiuid in contact with the other face of said fiexible sheet; and means to place said body of fiuid under pressure to cause said flexible sheet to press said blank into intimate contact with said forming surface.

6. An apparatusfor forming ablank to a predetermined configuration, including: means presenting a forming surface to one side of the blank; walls forming a space on the other side of the blank; a body of fluid in said space; a diaphragm spanning said space and separating said fluid from said blank; a floating forming member interposed between a portion of said blank and a portion of said diaphragm; and means to place said fluid under pressure to exert pressure against said floating member and to force said blank into intimate contact with said forming surface.

7. An apparatus for forming a blank to a predetermined configuration, including: a plurality of forming members having surfaces correspond ing to portions of said predetermined configuration, said members being presented to one side of said blank and at least one of said members being movable; walls forming a space on the other side of the blank; a body of fluid in said space; a diaphragm spanning said space and separating said fluid fromsaid blank; a floating member interposed between a portion of said diaphragm and a portion of said blank, said floating member having a contact surface for the blank complementary to a portion of the surfaces of said plurality of forming members; a first control means operatively associated with 'at least one movable member of said series of forming members to shift the disposition of the forming members from a disposition corresponding to an initial configuration for the blank to a disposition corresponding to said predetermined configuration; and a second control means to place said body of fluid under pressure to press said blank into intimate contact with said forming members at successive dispositions of the forming members.

8. An apparatus for forming a blank to a predetermined configuration, including: forming means presenting a forming surface to one side of the blank; walls forming a space on the other side of the blank; 9. body of fluid in said space; a diaphragm spanning said space and separating said fluid from said blank; means to place said fluid under pressure to force said blank into intimate contact with said forming surface; means to place said forming means under pressure in opposition to said fluid pressure to urge the forming means toward said diaphragm; and means to fluctuate at least one of said pressures to cause said forming means to shift intermittently thereby to shape said blank by progressive stages.

9. An apparatus for forming a blank to a predetermined configuration, including: forming means presenting a forming surface to one side of the blank; walls forming a space on the other side of the blank; a body of fluid in said space; a diaphragm spanning said space and separating said fluid from said blank; means to place said fluid under pressure to force said blank into intimate contact with said forming surface; means to place said forming means under pressure toward said diaphragm substantially balancing the pressure of the body of fluid; and means to fluctuate one of said pressures to unbalance the pressures intermittently to cause said forming means to shift intermittently thereby to shape said blank by progressive stages.

10. An apparatus for forming a blank to a predetermined configuration, including: a plurality of forming members having surfaces corresponding to portions of said predetermined configuration, said members being presented to one side of ing movable; walls forming a space on the other side of the blank; a body of fluid in said space; a diaphragm spanning said space and separating said fluid from said blank; a floating member interposed between a portion of said diaphragm and a portion of said blank, said floating member having a contact surface for the blank complementary to a portion of the surfaces of said plurality of forming members; means to place said body of fluid under pressure to exert pressure on said floating member to press said blank into intimate contact with said forming members; means to place at least one movable member of said plurality of forming members under pressure to substantially balance the pressure of said body of fluid; and means to upset the balance of said pressures intermittently to cause at least said one movable member of said plurality of forming members to shift the relative dispositions of the forming members intermittently and progressively from dispositions corresponding to an initial configuration for the blank to relative dispositions corresponding to said predetermined configuration thereby to cause the blank to be shaped progressively in stages,

11, An apparatus for forming a blank to a predetermined conflguration, including: a movable male die presenting a drawing surface; an adia cent stationary die presenting a stationary forming surface; means to advance the male die against the blank; hydraulic means to press a progressively increasing portion of the blank into intimate contact with the advancing male die with suflicient force to freeze said portion to the male die therebyto prevent rupture of the blank; and a die complementary to said stationary die to press adjacent portions of said blank against said stationary die.

12. An apparatus for forming a blank to a predetermined conflguration, including: a movable male die presenting a drawing surface; a surrounding stationary die presenting a stationary forming surface; means to advance the male die intermittently against a portion of said blank; hydraulic means to press the blank into intimate contact with the advancing male dieto prevent rupture of the blank; and variable means to press marginal portions of said blank against said stationary die during pauses in the advancement of the male die.

13. An apparatus for forming a blank to a predetermined configuration, including: a receptacle adapted to receive said blank in its entirety; an inner die and a surrounding outer die cooperating to form a cover to close said receptacle, said inner die being movable to various positions relative to said outer die to change said cover to various forming configurations; control means movably supporting said inner die; index means to indicate the position of said inner die relative to said outer die; a body of fluid in said receptacle;

and means to place said body of fluid under said blank and at least one of said members bepressure to force said blank against said inner and outer dies.

14. An apparatus for forming a blank to a predetermined conflguration, including: a plurality of contiguous forming members adapted for relative movement while still contiguous from a disposition providing an initial forming configuration to a predetermined disposition providing said predetermined configuration; means cooperating with said plurality of forming members to form a chamber completely enclosing said blank with one side of the blank facing said forming members; flowable means including a body of fluid progressively forming the blank to said predetermined configuration.

15, A method of forming a blank through a progressive series of intermediate configurations of the blank as a whole to a predetermined configuration of the blank as a whole, including the steps of: providing contiguous forms relatively movable through a progressive series of dispositions to present contiguous forming surfaces conforming to said intermediate and predetermined configurations of the blank as a whole; disposing said forms in initial positions for such progressive relative movement; completely enclosing said blank in a position with one side of the blank facing said forms; enclosing fiowable means including a body of fluid on the other side of said blank; causing relative progressive movement of said forms from said initial disposition to the disposition conforming to said predetermined configuration; and applying pressure to said body of fluid to force said blank into intimate contact with said contiguous surfaces to cause the configuration of the blank to follow the changes in disposition of the forms.

16. A method of forming a blank through a progressive series of intermediate configurations of the blank as a whole to a predetermined configuration of the blank as a whole, including the steps of: providing forms relatively movable through a progressive series of dispositions conforming to said intermediate and predetermined configurations of the blank as a whole; completely enclosing said blank in a position with one side of the blank facing said forms; enclosing fiowable means including a body of liquid on the other side of said blank; causing relative movement by stages of said forms from an initial disposition to a final disposition providing said predetermined configuration; applying pressure to said body of fluid to force said blank against said forms; and reducing said pressure during each stage of relative movement of said forms toward said final disposition. v

17. A method of forming a blank through a progressive series of intermediate configurations to a predetermined configuration, including the steps of: providing a plurality of forms relatively movable through a progressive series of dispositions conforming to said intermediate and predetermined configurations; disposing said forms in initial position sic! such progressive relative movement; placing said blank in a position with one side of the blank facing said forms: placing an inner form on the other side of said blank opposite one of said plurality of forms; placing fiowable means including a body of fluid on said other side of said blank and against the inner side of said inner form; causing relative progressive movement of said plurality of forms from said initial disposition to the disposition conforming to said predetermined configuration; and applying pressure to said body of fluid to force said inner form against said blank and force the blank against said plurality of forms thereby to cause the configuration of the blank to follow the changes in disposition of said plurality of forms.

18. Al method of forming a blank through a progressive series of intermediate configurations to a predetermined configuration, including the steps of providing a plurality of forms relatively movable through a progressive series of dispositions conforming to said intermediate and predetermined configurations; placing said blank in a position with one side of the blank facing said forms; placing an inner form on the other side of said blank opposite one of said plurality of forms; placing fiowable means including a body of fluid on said other side of said blank and against the inner side of said inner form; causing relative movement by stages of said forms from an-initial disposition to a final disposition conforming to said predetermined configuration; applying pressure to said body of liquid to force said inner form against said blank and force the -bers being adapted for relative movement for varying presentation of said surfaces to define a varying forming configuration; means for causing relative movement of said forming members from a first disposition in which the presented portions of said surfaces correspond to a first configuration of said blank to a second disposition of said forming members in which the presented portions of said surfaces correspond to said predetermined configuration; a receptacle containing a body of fluid; a flexible member comprising one wall of said receptacle disposed for movement to press the blank against said forming members; and means to place said body of fluid under pressure at successive relative dispositions of said forming members.

20. An apparatus for forming a blank to a predetermined configuration, including: a plurality of wall members defining a chamber, one side of said chamber presenting a forming surface, at least one of said wall members on one side of said chamber being relatively movable toward and away from the opposite side of the chamber for varying the configuration of said forming surface; a fiexible sheet spanning said chamber between said two sides of the chamber in a position for movement toward and away from said one side of the chamber to force said blank against said forming surface; means to cause relative movement between said wall members to vary the configuration of said forming surface; and means to apply fluid pressure to said flexible member to press said blank into intimate contact with said forming surface to shape the blank to successive configurations of the forming surface.

21. An apparatus for forming a blank to a predetermined configuration, including: die means; means cooperating with said die means to form a chamber completely enclosing said blank with one side of the blank facing said die means, said die means being movable toward said blank from a position at which the surface of said die means together with the adjacent surface of said cooperating means forms a combined forming surface of an initial configuration to an advanced position at which the surface of said die means together with the adjacent surface of said cooperating means forms a combined forming surface 01! said predetermined conflgurato move said die means inward in opposition to tion; iiowable means including a body of fluid in said sustained pressure to form said blank prosaid chamber 'on the other side of said blank; gressively in said predetermined configuration; means 'zto' place said body 01' fluid under sus-' and means to release fluid from said chamber distsined pressure .to force said blank into intimate 6 placed by said inward movement or the die means contactwith said combined forming surface-sat without releasing said pressure.

the diluent posiitons of said die means, means HENRY COLLIER SMITH, JR.

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