US2728317A - Apparatus for hydraulic die forming - Google Patents

Description

w. s. CLEVENGER ETAL 328 APPARATUS FOR HYDRAULIC DIE FORMING a9 Fi c1. 3.

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APPARATUS FOR HYDRAULIC DIE FORMING 2 Sheets-Sheet 2 k Nev L & we -/O6 INVENTORS We WALTON $.CLEVENGER 5 y Joel. S. COHEN W SANDERS G. COHENQ United States Patent 2,728,317 APPARATUS FOR HYDRAULIC DIE FORMING Walton S. Clevenger, Hialeah, and Joel S. Cohen and Sanders G. Cohen, Miami, Fla.

This invention relates broadly to an apparatus for the shaping of various materials in sheet or tubular form by the use of a pressurized hydraulic medium.

Basically, the method utilizes a female die, into which the material or materials to be formed will be pressed or a male die around which the materials to be formed will be forced, utilizing the force exerted by a pressurized hydraulic medium, which will, as the case may be, take the place of a mating die in the conventional method of forming. More specifically, the invention pertains to the novel manners in which advantage is taken of the forces of the working hydraulic medium and the functioning of the devices and equipment related to it, to more easily and economically arrive at the required results and at the same time to eliminate various mechanisms that are now deemed essential and to introduce to the art a more effective and eflicient means of forming various articles from sheet or tubular material in a minimum of time and with a minimum of equipment.

The invention contemplates the directing of a pressurized hydraulic medium in direct contact with the material to be formed, thereby requiring no diaphragm or membrane.

The primary object of the invention resides in forming or shaping of either sheet or tubular material into a female die or around a male die by the application of the external pressure of a pressurized hydraulic that exerts the forming pressure throughout the period necessary to completely conform to the die.

Further objects and advantages of the invention and methods and means for the control and operation thereof will be more readily understood by reference to the following detailed specification, taken in connection with the drawings, wherein has been illustrated various examples of the devices and wherein like characters of reference ar employed to denote like parts throughout.

In the drawings:

Figure 1 is a view in vertical section with the parts separated to more clearly illustrate an assembly and showingthe control means for the hydraulic fluid in diagrammatic form,

. Figure 2 is a vertical section of an assembled female die for use in the device of Figure 1,

Figure 3 is a vertical section of a modified form of the device,

Figure 4 is a side elevation illustrating a battery of pressure chambers for the dies,

Figure 5 is a side elevation of an elongated pressure chamber for the reception of multiple dies,

Figure 6 is a vertical section of a modified form of die,

Figure 7 is a similar view of die,

Figure 8 is a similar view of a further modified form of die,

Figure 9 is a similar view of a further modified form of die,

of a further modified form Figure 10 is a further modified form of the device,

Figure 11 is a section illustrating a deep cavity die and,

Figure 12 is a similar in the die of Figure 11.

Since the invention resorts primarily to the application of external pressure of a hydraulic medium upon an assembled die, either female or male, wherein a sheet to be formed is retained in overlying position over a die cavity or over a male die, examples of such a structure and method will be briefly described. Referring first to Figures 1 and 2, a pressure chamber 5, of any predetermined depth, size and contour, is provided with a circumferential flange view illustrating the final forming A die, indicated as in Figures 1 and 2 is chamber 5 and will from the pump 15 to a fluid line 19, communicating with the pressure chamber 5. Gauges 2t and 21 may be arranged upon either side of the valve 18. Arranged in the line 19, is a surge pump 22, for a purpose to be later described. A fluid return line 23, communicating with the line H and the reservoir 13, has a control valve 24 therein to control the return of the fluid to the reservoir. A by-pass line 25, having a pressure relief valve 26 therein, is an added safety relief against excessive pressure being built up in the chamber 5. While a system of controlling the flow and return of the hydraulic fluid has been shown more or less diagrammatically, it will be apparent, that the invention is not restricted to this particular arrangement.

An example of a die and a sheet to be pressure formed is illustrated in Figure 2 on an enlarged scale. The die, shown at 27, is of any desirable shape or size, capable being positioned within the pressure chamber 5. The die 27 is provided with an annular flange 28, tapped and threaded for the reception of attaching bolts 29, cover plate 30. The die as shown, has an upper face formed flat, with its circumferential edge provided with a shoulder 31 entirely therearound. The shoulder is of a height substantially the thickness of the metal formed. It may be found desirable, however, to eliminate the shoulder and have the plate 363 bear directly upon diameter or shape. 32, an air relief line suitable connection erably controlled by a relief valve 34, chamber.

In the use of this form of the invention, a suitable die 27 is prepared with a cavity having the desired contour. The sheet 35, to be formed is placed upon the flat surface of the die and lies substantially flush with the upper surface of the shoulder 31. The cover 30 is then bolted in position by the bolts 29 and exerts a slight pressure upon the outer areas of the sheet 35. The assembled die and plate are then placed within the pressure chamber 5 and supported in any desirable manner, not shown and the chamber cover 6 securely bolted in covering position. Fluid from the reservoir 13 is then pumped through the line 14 after the valve 15 has been opened and passes through the line 19 to the chamber 5. As the chamber is filled, entrapped air is relieved through the valve 8 until the chamber has been completely filled, at which time the valve 8 is closed and pressure continues to build up. The particular fluid employed is preferably oil and as the pressure increases, the force is exerted at every point around the die with the pressure impinging against the sheet 35, through the opening 31. The continuously increasing hydraulic pressure causes the sheet 35 to conform to the die cavity 32 and, since the pressure is equalized at all points, the contact of the sheet 35 with the marginal edges of the die cavity 32, creates its own seal. At such times as the seal is not immediately formed between the sheet and the die, 'the surge pump is operated to cause the hydraulic fluid to quickly snap the sheet into perfect sealing engagement with the die body. The engagement of the cover 30 is such as to permit the material of the sheet 35 dragging over the circumferential edges of the die cavity as the sheet is forced downwardly to conform to the cavity. Any air or fluid trapped in the die cavity will escape through the vent 33. The pressure of the cover 34 upon the sheet 35 is adequate to permit the dragging of the sheet into the cavity, but will prevent any tendency of the sheet to wrinkle during the conforming to the cavity.

it will be readily understood, that in this procedure, an equalized pressure is exerted over the entire surface of the material being formed immediately upon the introduction of the hydraulic pressure to the chamber 5 and this condition continues throughout the period that the pressure is working. It should be also understood, that as the various areas of the material being formed reach the face of the die which determines its ultimate shape, the exerted pressure of the hydraulic continues pressing against the then backed up material, holding it against the die. Further movement of this backed up material is not eliminated, as it can still be dragged over the face of the die as the forming process continues and more material is needed to arrive at the deeper recesses in the cavity as the pressure is increased. This accomplishment of retaining the material against the die body as the material enters deeper into the cavity, eliminates practically all chance for the material being formed to wrinkle as the added pressure necessary to continue the forming along with the resistance of its dragging over that area already formed, maintains the material in direct contact with the die face once it has arrived there sufliciently close to prevent leakage of the hydraulic pressure from the pressurized side of the material into the die cavity, even though its shape changes as it travels deeper into the cavity.

Due to this proven condition, it has been found that a complete elimination of the conventionally known sealirig mediums is possible and these findings are therefore designed into the whole arrangement whereby the hydraulic pressure exerting itself against the material being formed, also holds said materials against a metallic or similarly resistant area bordering that part of the die utilized in forming the material. As the material is forced against this bordering area and dragged over its edges by the force of the hydraulic pressure, it forms its own seal. While the die illustrated shows but a single point of seal, it should be understood that the die or dies may have various seals that may or may not have points of tangenecy to or across other sealing areas. Pressures in excess of 5000 pounds per square inch has been held as long as desired with this particular form of die and it is reasonable to assume that much higher'pressures may be obtained and held, if needed, as the pressure itself is responsible for the sealing condition.

It is to be understood, that this method can be of a single step forming in many cases, but is not limited to such. Progressive female and male dies or alternating female and male progressive combinations may be utilized in cases of extreme distortion of material being formed.

in Figure 3 of the drawing, a modified form of combined die and pressure chamber has been illustrated. The die body 36 is provided with the upper circumferential flange 37, extending outwardly from the hat top 38 of the die. A die cavity 39 of any desired contour is formed in the body. A preferably domed cover 443 having a diameter substantially equal to that of the flange 37, serves to cover the die and the work to be formed. The cover 40 is maintained in engagement with the die flange 37 by any suitable sectional channeled ring 47 that is engageable over the flange 37 and the circumferential edge of the cover 49. A pressurized fluid inlet 42 is connected to the domed cover 45 while a bleed line 43 controlled by any suitable valve device, not shown, is connected to the dome at its uppermost point. The material to be formed, shown at 44, is positioned upon the die face 38, over tying the cavity 39' and a cover plate 45, apertured at 46, is positioned upon the material 44. Clamps47, engage over the marginal edge of the cover plate 45 and are securely bolted to the die body, by bolts 48. The clamps 47 serve to snugly bind the material 44 to the face of the die, yet permit movement of the material inwardly as the pressure is exerted thereon through the opening 46. As the material enters the cavity 39, it is drawn over the points 49, creating a positive seal against the leakage'of hydraulic pressure to the cavity. The channelled ring 41 is provided with suitable seal rings or faces 50, to prevent leakage of the hydraulic pressure from the pressure chamber.

In the use of this form of the invention, the die 36 is assembled with the material 44 and cover plate 45 clamped thereto by the clamps. The domed cover 40 is then positioned over the die and the channel ring 41 engaged over the flange 37 and the edge of the cover 40. Hydraulic fluid under pressure is then admitted through the line 42 and the line 43 opened to permit the escape of entrapped air. As the pressure builds up in the device, there is a tendency for the die body and domed cover to move apart. Such movement causes a positive seal against the seals 50, preventing escape of the pressure. When a solid head of hydraulic pressure has been established in the dome, the bleed line is closed and the continued pressure then causes the material to be forced to conform with the cavity 39. As the material is dragged over the seal points 49, a positive seal is established and so continues during the forming of the material. Any leakage of fluid past the seal points 49 prior to the establishment of the pressure seal, will escape through a relief line 51, leading from the lower point of the cavity 39. Hydraulic fluid control means similar to that illustrated in Figure 1 may be employed in connection with this form of theinvention.

Figure 4 illustrates a battery of pressure chambers 5, similar to that illustrated in Figure l, and a common pressure line 19 communicates with the several chambers, with the several chambers being individually controlled by cut-oil valves 52. While but three chambers 5 have been illustrated, it will be obvious that as many may be employed as shall be found desirable for multiple and simultaneous forming. In the event of leakage from any chamber, its particular valve 52 may be closed, without interrupting the continuous actions of the other chambers. Further, a particular chamber can be loaded while others are in process of forming.

Figure 5 illustrates an elongated chamber into which a number of die devices may be placed for simultaneous forming. This chamber is denoted by the numeral 53. A hydraulic line 19 establishes communication from the source of pressure to the chamber and a cut-off valve'54 serves to interrupt the flow of the hydraulic medium. in all other respects, the operation of the forms of the inventionshown in Figures 4 and 5, are identical to that of Figure 1.

Figure 6 illustrates a further modification of the imfor use in connection with the pressurized chamber of Figures 1, 4 and 5. The device of Figure 6, embodies a body partion 55, having an opening 56 therethrough. The upper and lower fiat faces 57 of the body terminate in upstanding shoulders 58 entirely therearound. However, as in Figure 2, the shoulders may be omitted and the cover plates 60 bear directly upon the material to be formed. The shoulders 58 have a height corresponding to the thickness of the material to be formed. The material 59 in the present instance, engages both faces 57 and cover plates 60, apertured at 61, are bolted against the shoulders 58, through the medium of bolts 62 and snugly bind the material 59 in engagement with the flat faces 57. The body 55 is vented at 63. The device of Figure 6 is a double face die, providing means to form duplicate sheets of material around an object 64, placed within the opening 56 of the body. With the die assembled, as shown, with the object 64 therein, it is placed within a pressure chamber similar to that shown in Figure 1. As the pressure is increased, the material 59 travels inwardly to conform to the object 64, and as the material is dragged inwardly, a seal between the material and the body is established at the points 65.

Figure 7 illustrates a still further modified use of a hydraulic die forming for use in the pressurized chamber 5. In this form of the invention, a body 66 is formed of any desired shape and size, having a flat upper surface 67, the marginal edges of which are shouldered at 68 for the seating reception of a retaining cover plate 69. The plate 69 is apertured at 70. The plate is bolted to the body by bolts 71, as in the other forms of the device. The upper surface 67 is recessed at 72, providing seal points 73. A male die, indicated at 74, is secured in any desirable manner within the recess 72 and is provided with a vent 75, communicating with a vent opening 7 6, formed in the body 66. The material to be formed, indicated at 77, is preshaped to overlie the die 74 and its marginal edges are formed flat for clamping engagement upon the surface 67, beneath the plate 69. The operation of this form of the device is identical to the others, and having been placed within the pressure chamber, pressure is exerted upon the material from all angles, causing the material to first seal upon the points 73, after which it is progressively pressed inwardly and around the die 74, the marginal edges of the material being dragged inwardly over the sealing points.

The device shown in Figure 8 illustrates a means for forming duplicate shapes and consists of duplicate die bodies 78, having mating flanges 79. The mating faces of the die bodies, indicated at 80, terminate in marginal shoulders 31. The die bodies are provided with die recesses of the deesired contours, indicated at 82, vented at 83. A pressurizing plate 84 of suitable thickness, is provided with a central opening 85. Hydraulic pressure inlet openings 86 are formed through the plate radially and establish communication with the hydraulic pressure of the pressure chamber to the opening 85 of the plate. The material sheets 87 to be formed are jointly clamped against the faces of the dies through the medium of the plate 84 and clamping bolts 83, passing through openings formed in the flanges 79. The operation of this form of the device is identical to the others. With the die devices assembled as shown, the device is placed within the pressure chamber and, as the pressure is exerted thereon, pres sure passes through the openings 85 to impinge upon the material 37 in opposite directions. The material is thus forced simultaneously into the die cavities 82, being dragged inwardly as the pressure increases and creating a positive seal at the points 89.

The device illustrated in Figure 9, embodies a pair of die bodies 90, having flat abutting faces 91. The dies are oppositely faced and are provided with die cavities 92 of the desired contour. Material clamping plates 93, apertured at 94, are of a width to extend beyond the dies proved die forming,

and serve to clamp material sheets 95 against the working faces of the dies in overlying position with respect to the cavities 92. Bolts 96 serve to clamp the dies and plates 93 into a rigid structure with the material 95 in forming position. The dies are vented at 97. The device of Figure 9 is then placed in the pressure chamber as before.

The device illustrated in Figure 10, provides a means for forming a pair of sheets of material around a particular object, illustrated at 98. The sheets, illustrated at 99, are preferably preshaped to generally encase the object 98 and its marginal edges are soldered or otherwise sealed against the passage of hydraulic pressure therein. A vent opening 99 serves to relieve entrapped air within the chamber formed by the two sheets 99. After assembly, the device is placed within the pressure chamber and the sheets pressure formed around the object 98. After forming, the marginal edges are separated or cut away, providing a pair of formed sheets, each representing substantially one half of the object 98.

The device of Figures 11 'and 12 illustrates a deep cavity die for forming progressively a sheet of material into a deep cavity 100, provided in a die body 101. The working face 102 of the die, is provided with a seal 103, while a second seal 104 is arranged inwardly of the cavity opening. The sheet 105, to be formed, is maintained in engagement with the die face through the medium of the clamping plate 106, apertured at 107. In Figure 11, the sheet 105 has been partially formed, with the hydraulic seal being created at the seal point 103 and this forming progresses until the material has travelled past the seal 103. For a continuous and progressive forming of the material to conform to the deep cavity, it now becomes necessary to replace the plate 106 with a plate 108 having an extension 109 that engages the preformed material at a point adjacent the seal 104. The device is then again subjected to hydraulic pressure and the sheet is progressively formed to the bottom of the cavity 100, the pressure seal being maintained at the point of contact of the extension 109 and the seal 104. The cavity is vented in the usual manner at 110.

It will be apparent, that the basic operational conditions and procedures are the same throughout the several forms of the device, although the individual designs may vary of necessity to adapt it to a specific die problem at hand. The die or dies and their covers may be bolted or clamped together or held by any convenient means or by a press, or may utilize the same internal pressure exerted to force protruding flanges against retaining frames, as in Figure 3. Parting surfaces between dies and covers may be in a plane or may follow the general curve of the die face when so desired.

In the construction of dies or of mating dies for a given article, this most s' ple method of contour copying which leaves a shell around which the die or its mold may be formed, constitutes an appreciable saving, not only in cost, but in time consumed in the construction and study of the dies in process and also in the study and repair of worn dies. It is an evident fact, that since only a single die is needed in this method of forming, the die cost is greatly diminished. The cost of a mating die is eliminated, besides the great amount of work necessary in fitting the two into a workable combination. The die cost is so low, that it is economically possible to die form many parts that ordinarily could not be considered due to the fact that the number of pieces required could not possibly absorb the outlay in conventional die forming. A further great saving is elimination of the need for expensive and enormously heavy presses. The dies may made of any sufiiciently resistant material and may have the sealing area around them of the same material or of more resistant material as an inlay or as a bordering frame.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

In combination, a pressurized chamber having a removable cover and a seal between the cover and the chamber, a work forming die, a source of hydraulic medium and control means for directing a fiow of pressurized hydraulic medium to the chamber, a surge pump positioned in the hydraulic directing means whereby to provide a sudden pressure to initially create a seal between the die and the sheet being formed, the die consisting of a die body provided with a predetermined die having a fiat work supporting face extending outwardly therearound for the support of a sheet of material to be formed, a shoulder formed around the periphery of the die that has a height corresponding to the thickness of the sheet to be formed, the sheet to be positioned upon the fiat face in overlying relation to the die contour and flush with the shoulder, an apertured clamping plate for binding the sheet upon the flat face, the die being vented to a point exteriorly of the chamber, the die and its supported sheet being wholly positioned within the chamher, the chamber when pressurized forcing the sheet to conform to the die contour through the aperture of the plate, the sheet being dragged from beneath the clamping plate to conform to the die contour, the dragging of the sheet into the die contour providing a fluid seal between the sheet and the die, the clamping plate preventing wrinkling of the sheet as it is dragged into the die.

References Cited in the file of this patent UNITED STATES PATENTS 669,279 Harrington Mar. 5, 1901 1,886,831 Murray Nov. 8, 1932 2,156,889 Wiley May 2, 1939 2,284,773 Sivian et al. June 2, 1942 2,399,775 Whistler et a1. May 7, 1946 2,459,316 Grarnelspacher Jan. 18, 1949 2,460,820 Hagopian Feb. 8, 1949 2,669,209 Hofiman Feb. 16, 1954

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