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Publication numberUS3751962 A
Publication typeGrant
Publication dateAug 14, 1973
Filing dateNov 6, 1970
Priority dateNov 6, 1970
Publication numberUS 3751962 A, US 3751962A, US-A-3751962, US3751962 A, US3751962A
InventorsCvacho D, Wallace J
Original AssigneeReynolds Metals Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method and apparatus for making a drawn article
US 3751962 A
Abstract  available in
Images(4)
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Claims  available in
Description  (OCR text may contain errors)

Cvacho et a1.

[ METHOD AND APPARATUS FOR MAKING A DRAWN ARTICLE [75] Inventors: Daniel S. Cvacho; Joseph W.

Wallace, both of Richmond, Va. [73] A Assignee: Reynolds Metals Company,

Richmond, Va.

[22] Filed: Nov. 6, 1970 [21] Appl. No.: 87,460

[52] US. Cl. 72/347, 72/350 [51] Int. Cl 321d 26/14 [58] Field of Search 72/347, 350, 351

[56] References Cited UNITED STATES PATENTS 2,243,986 6/1941 Stacy 72/351 2,605,731 8/1952 Schulze et al.... 72/20 3,420,089 1/1969 Myers 72/351 3,453,848 7/1969 Williamson 72/351 1,884,700 10/1932 Hothersall 72/351 2,075,847 4/1937 Hothersall t 72/351 3,236,088 2/1966 Moller 72/351 3,456,478 7/1969 Alexander 72/351 3,031,993 5/1962 Gerard et a1 72/19 [451 Aug. 14, 1973 FOREIGN PATENTS OR APPLICATIONS 132,028 10/1947 Australia 72/350 Primary ExaminerRichard J. Herbst Attorney-Glenn, Palmer, Lyne, Gibbs & Thompson [5 7] ABSTRACT An apparatus for drawing an article from a blank of material disposed between cooperating draw members and being drawn therefrom by a movable ram moving relative to the draw members and having a fluid chamber receiving piston portions of one of the draw members and the-ram whereby relative movement between the apparatus and the one draw member in one direction causes the blank drawing movement of the ram by the fluid action between the piston portions in the chamber. Restriction means are provided in the chamber for restricting fluid flow between the piston portions at least during the initial part of the drawing operation of said ram on said blank so that a back pressure is created on the one draw member to maintain sufficient holding force on the blank being drawn therefrom to prevent adverse wrinkles on the article being drawn.

30 Claims, 10 Drawing Figures PATENIEU 3.751.962

sum 1 OF 4 INVENTORS DANIEL S. CVACHO 8| JOSEPH W. WALLACE By 1mm), %944,

Lu) r J THEIR ATTORNEYS PAIENIEU I 3. 751 .962

sum 2 on} Has 60 '3 IT INVENTORS DANIEL S. CVACHO 8 JOSEPH W. WALLACE BY C am THEIR ATTORNEYS PAIENIEU NIB 1 sum 3 or 4 INVENTORS IEL S. CVACHO 8| EPH W. WALLACE THEIR ATTORNEYS METHOD AND APPARATUS FOR MAKING A DRAWN ARTICLE I BACKGROUND OF THE INVENTION In the manufacture of drawn and ironed container bodies each having a seamless cylindrical side wall means and an integral bottom wall means, each such drawn and ironed container body is normally made from a shorter cup-shaped member subsequently drawn and ironed in a drawing and ironed apparatus to the desired size.

The shorter and intermediate cup-shaped articles each have been formed by having a circular article or blank cut from a larger flat blank of material and then drawing such circular article into the intermediate cupshape by suitable press structure.

However, it has been found according to the teachings of the invention that many of the previously proposed apparatus and methods for making such intermediate cup-shaped articles for subsequent drawing and ironing into the seamless container bodies produced intermediate cup-shaped articles that had adverse wrinkles formed at the outer peripheries of the circular blanks during the drawing operation thereof and/or tended to fracture or split at the outer open ends thereof due to improper force being exerted on the cut articles by the drawing rings of the apparatus.

SUMMARY This invention provides an improved method and apparatus for making cup-shaped articles wherein the aforementioned adverse wrinkling and/or fracturing of the drawn cup-shaped articles are substantially eliminated.

One embodiment of this invention comprises an apparatus having cooperating draw members for receiving a blank of material therebetween and having a movable ram for drawing the blank from between the draw members into a cup-shapeby the ram moving relative to the draw members. The apparatus has a fluid chamber that receives piston portions of one of the draw members and the ram whereby relative movement between the apparatus and the one draw member in one direction causes the blank drawing movement of the ram. by the fluid action that takes place between the piston portions in the fluid chamber. Restriction means are provided in the chamber for restricting fluid flow between the piston portions at least during part of the drawing operation of the ram on the blank so that the fluid creates a back force on the piston portion of the one draw member greater than the force that would be created on such piston portion onlyby the resistance of the blank to the drawing action of the ram in order to provide a controlled holding force of the one draw member on the blank during the drawing operation therefrom to substantially eliminate the adverse wrinkling and/or cracking problem previously set forth.

Other details, uses, and advantages of this invention will become apparent as the following description of the exemplary embodiments thereof is presented in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings show the present exemplary embodiments of the invention, in which:

FIG. 1 is a perspective view of the apparatus of this invention.

FIG. 1A is a top perspective view of the drawn article formed by the apparatus of FIG. 1.

FIG. 2 is an enlarged, fragmentary, perspective and cross-sectional view illustrating the die parts of the apparatus of FIG. 1.

FIG. 3 is a fragmentary cross-sectional view illustrating the die parts of the apparatus of FIG. 1 before the die parts close against the blank of material.

FIG. 4 is a view similar to FIG. 3 and illustrates the die parts cutting a circular article or blank from the larger blank of material.

FIG. 5 is a fragmentary cross-sectional view illustrating the piston portion of the ram and draw ring when the die parts are substantially in the position of FIG. 4.

FIG. 6 is a fragmentary cross-sectional view illustrating the die parts of FIG. 2 during the drawing operation on the cut circular article or blank.

FIG. 7 is a graph illustrating the various draw pressures of the apparatus of this invention as well as prior art apparatus.

FIG. 8 is a view similar to FIG. 5 and illustrates another embodiment of this invention.

FIG. 9 is a view similar to FIG. 5 and illustrates an-' other embodiment of this invention.

DESCRIPTION OF ILLUSTRATED EMBODIMENTS Referring now to FIG. 1, the improved apparatus and method of this invention is generally indicated by the reference numeral 10 and comprises a frame structure 11 defining a die area 21 for receiving a metallic blank strip 13 fed thereto from a supply roll 14 by infeed rollers 15, the strip 13 passing through suitable lubricating rollers 16 to properly lubricate the strip 13 for a subsequent drawing operation thereon in the die area 12 of the apparatus 10 in a manner hereinafter described.

The die area 21 of the apparatus 10 includes a movable punch holder 17 movable relative to apparatus 11 in a manner hereinafter described by suitable ram means 18. The die area 21 also includes a stationary die shoe 19 carrying a plurality of piston and cylinder arrangements 20 corresponding to the same number of die punches 12 carried by the punch holder 17, the illustrated embodiment 10 providing four such punches l2 and four such-piston and cylinder arrangements 20. However, since each piston and cylinder arrangement 20 and its cooperating punch 12 are identical to the other piston and cylinder arrangements and their respec'tive punches, only one such piston and cylinder arrangement 20 and its cooperating punch 12 is illustrated throughout the drawings and described in detail hereinafter withthe understanding that such description applies to the other punches and their cooperating piston and cylinder arrangements of the apparatus 10 as any desired number thereof can be utilized.

' In general, an uncut portion of the strip of blank material 13 is indexed between the die shoe l9 and punch holder 17 and then the punch holder 17 is moved toward the die shoe 19 by the ram 18 to cause the strip 13 to be cut into a plurality of circular articles or blanks respectively by the punches l2 cooperating with the piston and cylinder arrangements 20. The piston and cylinder arrangements 20 thereafter cooperate with the punches 12 to subsequently form the cut circular articles into drawn cup-shaped articles, such as the cupshaped article 22 of FIG. IA which can be subsequently utilized in the aforementioned drawing and ironing apparatus to form a seamless container body of the desired size. The cup-shaped article 22 has a substantially cylindrical and seamless side wall means 23 provided with a closed bottom wall means 24 and an upper open end 25.

Referring now to FIG. 2, each punch 12 carried by the punch holder 17 is an annular member having a flat annular drawing surface 26 so as to provide a draw member for an apparatus as will be apparent hereinafter, the flat annular drawing surface 26 terminating at an inner annular arcuate drawing and ironing surface 27 at the punch bore to be utilized in a manner hereinafter described. A movable stripper 28 is telescoped around the punch. 12 and is adapted to be moved relative thereto by a plurality of pistons 29 respectively interconnected to the stripper 28 and having piston portions 30 thereof disposed in stationary cylinder means 31 carried by the punch shoe 17, the strippers 28 being utilized to hold or strip the blank strip 13 from the punches 12 after a drawing operation so that the blank skeleton can be subsequently indexed out of the die area 21 to bring an unblanked portion of strip 13 into the die area 21.

Each piston and cylinder arrangement that is carried by the die shoe 19 and cooperates with a punch 12 comprises a cylinder head 32 disposed in a suitable opening 33 of the stationary die shoe 19 so as to be stationary therewith while defining internally stepped cylindrical surfaces 34 and 35 with the surface 35 being closed off by an end wall means 36 having a central opening 37 passing therethrough and being provided with suitable bearing means 38 for supporting a ram structure 39 for axial movement within the cylinder head 32 for a purpose hereinafter described.

A die center or draw ring 40 has a piston portion 41 disposed in sliding and sealing engagement with the internal cylindrical surface 35 of the cylinder head 32 while having an annular cylindrical portion 42 disposed in sliding engagement with the internal cylindrical surface 34 of the portion of the cylinder head 32 that passes through the opening 33 of the die shoe 19. The die ring 40 defines an annular flat drawing surface 43 at the end thereof which is adapted to cooperate with the flat annular drawing surface 26 of the cooperating punch 12 in a manner hereinafter described whereby the draw ring 40 and punch 12 comprise draw members for the apparatus 10 as will be apparent hereinafter.

The draw ring 40 telescopically receives the ram head 44 of the ram structure 39 therein whereby the ram head 44 is adapted to move relative to the draw member surface 43 for a drawing operation as will be apparent hereinafter, the ram head 44 having a substantially flat circular end surface 45 that is arcuate in cross section at the edge 46 thereof as illustrated in FIGS. 3, 4 and 6 for cooperating with the arcuate surface 27 of the punch 12 in initially drawing and subsequently drawing and ironing the cut article from the strip 13 into the cylindrical cup-shaped article 22 of FIG. 1A.

The ram structure 39 also carries a piston portion 47 disposed in sliding and sealing engagement with an internal cylindrical surface 48 of the draw ring cylindrical portion 42 whereby the piston portions 41 and 47 of the draw ring 40 and ram structure 39 cooperate with the internal cylindrical surface 35 of the cylinder head 32 and the end wall means 36 thereof to define a fluid chamber 49 in the cylinder head 42 that respectively receives the piston portions 41 and 47 of the draw ring 40 and ram structure 39, the piston portions 41 and 47 cooperating together to close off the other end of the chamber 49.

In this manner, a fluid action can be provided in the chamber 49 between the piston portions 41 and 47 of the draw member 40 and ram 39 so that movement of the draw ring 40 relative to the chamber 49 in a direction to the left in FIG. 2 will cause the fluid in the chamber 49 to act against the piston portion 47 of the ram 39 and move the same to the right for the purpose hereinafter described. The chamber 49 is provided with a constant volume of a non-compressible hydraulic fluid, such as oil or the like, from a supply tank 50 that feeds fluid through a one-way check valve structure 51 to an inlet 52 leading to the chamber 49, the chamber 49 having an outlet 53 leading back to the supply tank 50 through a pressure relief valve structure 54 so that the pressure being exerted in the chamber 49 will not exceed a certain pressure.

The general operation of the piston and cylinder arrangement 20 and its cooperating punch 12 will now be described and reference is made to FIG. 3 wherein it can be seen that the strip of material 13 has an unblanked portion thereof indexed between the piston and cylinder arrangement 20 and the punch 12 when the same are spaced from each other. Thereafter, the punch holder 17 is moved to the left in FIG. 3 by the ram 18 whereby the punch 12 engages against the right side 55 of the strip 13 and compacts the other side 56 of the strip 13 against the draw ring 40 so that further movement of the punch 12 to the left will carry the draw ring 40 therewith to the left with the outer annular sharp edge 57 of the punch 12 cooperating with a stationary cut edge member 59 fixed to the stationary die holder 19 by interconnecting structure 60, FIG. 6, to cut a circular article or blank 61 from the strip of material 13 in the manner illustrated in FIG. 4 whereby the unblanked portion of the strip 13 is held between the cut edge member 59 and the stripper 28 while the outer peripheral part of the cut article 61 is held between the cooperating drawing surfaces 26 and 43 of the punch 12 and die member or draw ring 40.

It can be seen from FIGS. 3 and 4 that the amount of movement of the punch 12 to the left while carrying the draw ring 40 therewith to the left to cut the circular article 61 from the blank 13 has caused the ram 39 to move to the right and now have its flat circular end surface 45 engage against the side 56 of the cut blank 61 in the manner illustrated in FIG. 4, such rightward movement of the ram 39 during the leftward movement of the draw ring 40 taking place because of the fluid action in the chamber 49 acting between the piston portions 41 and 47.

In particular, as the piston portion 41 of the draw ring 40 is moved to the left in FIG. 2, the same tends to decrease the volume of the chamber 49 and since the chamber 49 is filled with a non-compressible fluid, the fluid drives against the piston portion 47 of the ram 39 to move the same to the right to compensate for the leftward moving piston portion 41, the effective sizes of the piston areas 41 and 47 being selected for the desired increment of movement of the ram 39 for each increment of movement of the draw ring 40.

Further movement of the punch 12 from the position illustrated in FIG. 4 to the left, such as illustrated in FIG. 6, causes the draw ring 40 to move to the left and the ram 39 to move to the right whereby the ram 39 cooperates with the punch 12 to. draw the flat article 61 into a cup-shape as the blank is drawn from between the cooperating draw surfaces 43 and 26 of the draw ring 40 and punch 12 over the rounded edge 27 of the punch 12 and over the ram face 43 to begin to form a cup-shape. The metal at the outer circumference of the circular article 61 tends to increase in thickness as the blank diameter decreases whereby the metal near the bottom radius of the forming cup is essentially stretched as the remainder of the blank is drawn with the bottom of the cup being substantially identical in thickness to the thickness of the original strip 13. The resistance of the blank 61 being drawn into the cup shaped structure 22 causes pressure to be built up in the chamber 49 which provides a back pressure on the cylinder portion 41 of the draw ring 40 to hold the blank 61 between the draw ring 40 and punch surface 26 whereby the drawing action provides a reaction for holding the blank 61 between the draw ring 40 and punch surface 26.

This build up of back pressure on the draw ring 40 created 'by the resistance of the blank 61 from being drawn into the cup-shape by the rightward movement of the ram 39 creates a draw pad pressure or pressure on the outer circumference of the blank 61 between the die holder surface 43 and the punch draw surface 26 in an increasing manner as represented by lines 62 and 63 on the graph 64 of FIG. 7 wherein the X axis represents the stroke of the ram 39 in inches during the drawing operation and the Y axis represents the draw pressure, line 62 being provided when the hydraulic relation between the piston portions 41 and 47 is two to one and line 62 being provided when the hydraulic relation between the piston portions 41 and 47 is one to one.

However, it has been found according to the teachings of this invention that if during the initial drawing of the article 61 into the cup shape when the blank 61 is still having a large diameter provided between the drawing surfaces 43 and 26 of the draw ring 40 and punch 12 and the pressure therebetween is relatively small, the outer diameter portion of the blank 61 tends to wrinkle and thereby provide radial grooves therein which during the subsequent drawing and ironing operation between the ram 39 and punch 12 are not completely eliminated and are merely smoothed over to provide a defective surface structure at the upper open end 25 of the cup shaped article 22. Further, it has been found that as the article 61 is being drawn from between the draw surfaces 43 and 26 of the draw ring 40 and punch 12, should the holding pressure therebetween. become too great when the diameter of the drawn article 61 still remaining between the draw surfaces 43 and 26 becomes smaller, such excess pressure on the outer peripheral portion of the blank 61 causes the same to be thinned out to too great an extent so that fractures and cracks occur at the open end 25 of the resulting cup-shaped article 22. Obviously, either one of these adverse features prevents the defective cupshaped article 22 from subsequently forming an acceptable container body.

Thus, according to the teachings of this invention, an ideal draw pad pressure between the surfaces 43 and 26 of the draw ring 40 and the punch 12 would be to initially begin with a relatively large pressure therebetween and then continuously decrease that draw pad pressure therebetween as the blank 61 is being drawn into its cup shape, such ideal draw pad pressure being represented by the line 65 on the graph 64 of FIG. 7.

Thus, it is one of the features of this invention to provide means for initially creating a back pressure on the piston portion 41 of the draw ring.40 greater than the force imposed thereon that would be created solely by the resistance of the flat blank 61 to the initial drawing action of the ram 39 thereon as represented by the line 62 or 63 on the graph 64 of FIG. 7.

One embodiment for providing such feature comprises a cylindrical spool 66 being carried by the piston portion 47 of the ram 39 and an annular control ring 67 being carried by the piston portion 41 of the draw ring 40 with the annular control ring 67 having its inner peripheral surface 68 adapted to telescope with the outer cylindrical surface 69 of the spool 66 in a controlled manner to provide an annular restricting spacing 70 therebetween in a manner hereinafter set forth, the restricted spacing 70 being so arranged that the same interconnects together a first chamber part 71 of the chamber 49 with a second chamber part 7.2 of the chamber 49 when the control ring 67 is cooperating with the spool 66 to divide the chamber 49 into the two chamber parts 71 and 72 as illustrated in FIGS. 2, 5 and 6. In this manner, when the draw ring 40 is initially being moved to the left by the punch 12, the hydraulic fluid in the chamber 49 being displaced by the piston portion 41 to act on the piston portion 47 of the ram 39 must pass through the restricted spacing 70 between the control ring 67 and spool 66 so that a back pressure is immediately created'on the piston portion 41 of the draw ring 40 to resist such leftward movement of the draw ring 40 during the initial part of the drawing stroke with such action on the draw ring 40 producing a draw pad pressure as represented by the line 73 on the graph 64 of FIG. 7 whereby it can be seen that an initial build-up of draw pad pressure is created by restricting the fluid flow between the piston portions 41 and 47 of the draw ring 40 and ram 39. The spool 66 and control ring 67 can be so constructed and arranged that at a certain point in the drawing operation, the spool 66 drops off in that the control ring 67 moves beyond the lefthand side 74 of the spool 66 so that no longer is a fluid flow restriction provided between the piston portions 41 and 47 whereby the back pressure on the draw ring 40 falls off at the point 75 in the line 73 on the graph 64 of FIG. 7 until approximately at the point 76 thereon the drawing and ironing action between the ram 39 and punch surface 27 begins to create a resistance to the rightward movement of the ram 39 which in turn creates its own back pressure on the draw ring 40 to cause the draw pad pressure to begin increasing.

Nevertheless, it can be seen that the draw pad pressure as represented by line 73 on the graph 64 of FIG. 7 that is provided by the straight cylindrical surface 69 on the spool 66 and straight cylindrical surface 68 on the control draw ring 67 create an initial back pressure on the draw ring 40 so that an initial large draw pad pressure is created between the surfaces 43 and 26 of the die ring 40 and punch 12 on the blank 61 to prevent the adverse wrinkling at the outer diameter thereof with such pressure falling off as the diameter of the blank 61 remaining between the draw surfaces 43 and 26 becomes smaller so that an excess pressure will not be acting thereon to provide the adverse aforementioned thinning out and subsequent fracturing and cracking at the open end of the subsequently cupshaped article 22.

Of course, by varying the configuration of the control surface 69 of the spool 66, the draw pad pressure can be programmed in a desired manner.

For example, by providing one or more tapering grooves 77 in the cylindrical surface 69 of the spool 66 with such grooves 77 getting deeper as they extend toward the lefthand end 74 of the spool 66, as illustrated in FIGS. and 6, the back pressure action on the piston portion 41 of the draw ring 40 can progressively decrease after the initial large build-up of pressure thereon as represented by the line 78 on the graph 64 of FIG. 7.

Thus, it can be seen that the line 78 on the graph 64 of FIG. 7 provides an initial large draw pad pressure which begins to progressively fall off and follow the ideal draw pad pressure line 65 during the increasing stroke of the apparatus 10 until at the point 79 where the drawing and ironing action between the ram 39 and punch 12 takes over to provide a greater resistance to the rightward movement of the ram 39 and thereby again increase the draw pad pressure for the reasons previously set forth.

Nevertheless, the grooves 77 provide a draw pad pressure arrangement substantially identical to the ideal draw pad pressure 65 in that an initial high draw pad pressure is provided during the initial drawing operation to eliminate the aforementioned wrinkles in the outer peripheral portion of the blank 61 and to eliminate high adverse forces on such outer peripheral portions as the diameter of the article between the holding surfaces 43 and 26 decreases because of the drawing action thereon.

By way of example, and not for purposes of limitation on this invention, when the diameter of the blank 61 is initially approximately 5.280 inches, the internal diameter of the control ring 67 can be approximately 3.000 inches and the diameter of the spool 66 can be approximately 2.920 inches in order to produce the draw pad pressures represented by lines 78 and 73 on the graph 64 of FIG. 7.

Of course, instead of providing tapering grooves 77 in the spool 66 of the ram 39 to provide for the progressive increasing in the size of the restriction between the chamber parts 71 and 72 as the drawing operation proceeds, the outer surface 69 of the spool 66 could be contoured in any desired manner.

For example, reference is now made to FIG. 8 wherein another embodiment of this invention is generally indicated by the reference numeral 10A and parts thereof similar to the apparatus 10 are indicated by like reference numerals followed by the reference number A.

As illustrated in FIG. 8, the spool 66A of the piston portion 47A of the ram 39A has an initial flat cylindrical surface 80 which joins to the left thereof to a frustoconical surface 81 which joins to another flat cylindrical surface 82 which to the left thereofjoins to another frusto-conical surface 83 to provide a controlled falloff of the spool 66A with the control ring 67A. For example, the gap between the internal control surface 68A of the control ring 67A with the first cylindrical surface 80 of the spool 66A can be provided a gap of approximately 0.040 of an inch whereas the gap therebetween when the other cylindrical surface 82 is adjacent the control surface 68A of the ring 67A is approximately 0.030 of an inch so as to provide a greater resistance or restriction before the fall-off control surface 83 begins to increase the size of the restriction.

Accordingly, it can be seen that the feature of providing restricted fluid flow between the piston portions 41 and 47 of the apparatus 10 can be produced by different structures.

In order to assure proper and fast return of the ram 39 to the left and the draw ring 40 to the right for a subsequent drawing operation in the manner previously described, the effect of the fluid flow restriction between the chamber parts 71 and 72 can be eliminated by providing a one way check valve means for controlling fluid flow between the chamber parts 71 and 72 so that upon the return movement of the ram 39 and draw ring 40 to their open positions as illustrated in FIG. 3, the fluid flow between the chamber parts 71 and 72 will not be restricted by the spool 66 and control ring 67 as the fluid flow between the chamber parts 71 and 72 will be through the one way flow device.

For example, the control ring 67 can carry a plurality of one-way check valves 84 as illustrated in FIGS. 5 and 6 so that as the ram 39 is moving to the left to decrease the volume in the chamber part 72 thereof while the draw ring 40 is moving to the right to increase the volume in the chamber part 71 of the chamber 49, unrestricted fluid flow is provided from the chamber part 72 to the chamber part 71 through the one way check valve 84 so that no restricted flow is created between the chamber parts 71 and 72. However, upon the reverse movement of the ram 39- and draw ring 40 wherein the ram 39 is moved to the right upon movement of the draw ring 40 to the left during the drawing operation on the blank 61, the check valves 84 are maintained in a closed position so that all fluid flow between the chamber parts 71 and 72 must take place at the spool 66 and control ring 67 in the manner previously described.

Another apparatus of this invention is generally indicated by the reference numeral 103 in FIG. 9 and parts thereof similar to the apparatus 10 are indicated by like reference numerals followed by the reference letter B.

As illustrated in FIG. 9, a cylindrical sleeve 85 is disposed in the fluid chamber 498 of the apparatus 108 to separate the chamber 49B into two parts 718 and 728 with the cylindrical sleeve 85 being disposed against the internal peripheral surface 86 of the piston portion 41B of the draw ring structure 408.

The vertical sleeve 85 has one or more orifices 87 passing therethrough to interconnect the chamber part 71B to the chamber part 72B, the orifices 87 being fixed and being chosen to provide the desired restriction to fluid flow between the chamber 718 and the chamber 72B during leftward movement of the piston portion 41B of the draw ring 40B and rightward movement of the piston portion 47B of the ram 398 so as to provide the aforementioned initial large draw pad pressure through the back pressure being created on the piston portion 418 of the draw ring 408 because of the restriction being provided to the fluid flow through the orifices 87.

Since there is a slow down in the stroke motion of the ram 398 toward the end of its stroke, the orifices 87 permit more fluid to pass therethrough during such leftward movement of the piston portion 41B of the draw ring 40B whereby the draw pad pressure drops off toward the end of the draw stroke operation to provide a programmed control of the draw pad pressure so that an excess pressure is not being provided on the blank during the later stages of the drawing operation to cause the adverse thinning out thereof as previously mentioned.

In order to permit the fast return of the ram 398 and I draw ring 408 to their open positions where the ram 39B moves to the left and the draw ring 403 moves to the right, a suitable check valve or other one-way flow device 88 can be provided in the apparatus 108 to provide unrestricted one-way flow of fluid between the chamber parts 71B and 728 in a manner similar to the check valves 84 for the apparatus 10 previously described.

Thus, it can be seen that other means of providing restricted fluid flow between the piston portions of the ram and draw member can be provided to provide a programmed draw pad pressure closely resembling an ideal draw pad pressure to eliminate adverse defects in a'subsequently drawn cup-shaped article.

Thus, this invention provides an improved method and apparatus for making drawn articles from a blank of material.

While exemplary embodiments of this invention, and methods for practicing the same, have been illustrated and described, it will be recognized that this invention may be otherwise variously embodied and practiced within the scope of the following claims.

What is claimed is:

11. In an apparatus adapted for drawing an article from a blank of material adapted to be disposed between cooperating draw members and being adapted to be drawn therefrom by a movable ram moving relative to said draw members and with said apparatus having a single fluid chamber receiving coaxially arranged piston portions of one of said draw members and said ram whereby relative movement between said apparatus and said one draw member in one direction causes the drawing movement of said ram by the fluid action between said coaxially arranged piston portions in said chamber, the improvement comprising restricting and separating means on at least one of said piston portions and being located in said chamber, said restricting and separating means restricting fluid flow between said piston portions at least during part of the drawing operation of said ram on said blank, said restricting and separating means separating said chamber into two interconnected chamber parts and the fluid in one chamber part associates primarily with the piston portion comprising said one draw member and creates a back force on the piston portion of the one draw member greater than the force that would be created on said piston portion of the one draw member only by the resistance of the blank to the drawing action of the ram to thereby provide a controlled holding force of the one draw member on the blank during the drawing operation.

2. In an apparatus as set forth in claim 1, the further improvement wherein said restricting and separating means provides a varying restriction.

3. In an apparatus as set forth in claim 2, the further improvement wherein said restricting and separating means comprises means for progressively increasing the size of said restriction during at least said part of said drawing operation.

4. In an apparatus as set forth in claim 1, the further improvement whereinsaid part of said drawing'operation takes place during the initial part of said drawing operation. I

5. In an apparatus as set forth in claim 4, the further improvement wherein said restricting and separating means does not restrict such fluid flow during the remaining part of said drawing operation.

6. In an apparatus as set forth in claim 1, the further improvement wherein said restricting and separating means comprises a wall disposed in said chamber and separating said chamber between said piston portions into two chamber parts, said wall having a fixed orifice therethrough interconnecting said chamber parts together.

7. In an apparatus as set forth in claim 6, the further improvement wherein a one-way flow device also interconnects said chamber parts together to facilitate return of said ram to its non-drawing position relative to said apparatus.

8. In an apparatus as set forth in claim 1, the further improvement wherein said restricting and separating means comprises cooperating surfaces on said piston portions of said one draw member and said ram that separate said chamber between said piston portions intosaid two chamber parts, the spacing between said surfaces interconnecting said chamber parts together and providing said restricted flow.

9. In an apparatus as set forth in claim 8, the further improvement wherein a one-way flow device also interconnects said chamber parts together to facilitate return of said ram to its non-drawing position relative to said apparatus.

10. In an apparatus as set forth in claim 8, the further improvement wherein said piston portion of said ram is disposed within said piston portion of said one draw member, said surface of said ram comprising a spool, said surface of said one draw member comprising a ring telescoping with said spool during at least said part of said drawing operation.

11. In an apparatus as set forth in claim 10, the further improvement wherein said spool has a tapering surface to provide for a progressively increasing in the size of the restriction between said spool and said ring during at least said part of said drawing operation.

12. In an apparatus as set forth in claim 10, the further improvement wherein said spool has an outer cylindrical surface disposed coaxial with said ring during the entire telescoping relation therebetween, said cylindrical surface having at least one tapering groove therein to provide for a progressively increasing in the size of the restriction between said spool and said ring during at least said part of said drawing operation.

13. In an apparatus adapted for drawing an article from a blank of material adapted to be disposed between cooperating draw members and being adapted to be drawn therefrom by a movable ram moving relative to said draw members and with said apparatus having a single fluid chamber receiving piston portions of one said draw members and said ram whereby relative movement between said apparatus and said one draw member in one direction causes the blank drawing movement of said ram by the fluid action between said piston portions in said chamber, the improvement comprising restricting and separating means on at least one of said piston portions and being located in said chamber, said restricting and separating means causing said fluid to create a force on said piston portion of said one draw member greater than the force that would be created on said piston portion of said one draw member by the resistance of said blank to the drawing action of said ram thereon at least during part of the drawing operation of said ram on said blank, said restricting and separating means in said chamber separating said chamber into two chamber parts with the fluid in one chamber part associating primarily with the piston portion of said one draw member.

14. In an apparatus as set forth in claim 13, the further improvement wherein said part of said drawing operation takes place only during the initial part of said drawing operation so that said restricting and separating means does not effect the fluid force between said piston portions during the remaining part of said drawing operation.

15. In an apparatus as set forth in claim 13, the further improvement wherein said restricting and separating means varies the force on said piston portion of said one draw member during said part of said drawing operation. I 7

16. In a method for drawing an article from a blank of material disposed between cooperating draw members and being drawn therefrom by a movable ram moving relative to the draw members and with a single fluid chamber receiving piston portions of one of said draw members and said rarn so that relative movement between said one draw member and said fluid chamber in one direction causes the blank drawing movement of said ram by the fluid action between said piston portions in the camber, the improvement comprising the step of restricting fluid flow between-said piston portions at least during part of the drawing operation of said ram on said blank, with restricting and separating means located in said chamber, said step of restricting fluid flow with said restricting and separating means comprising separating said chamber into two interconnected chamber parts so that the fluid in one chamber part associates primarily with the piston portion comprising said one draw member and creates a back force on the piston portion of the one draw member greater than the force that would be created on said piston portion of the one draw member only by the resistance of the blank to the drawing action of the ram to thereby provide a controlled holding force of the one draw member on the blank during the drawing operation.

17. In a method as set forth in claim 16, the further improvement wherein said step of restricting fluid flow between said piston portions comprises the step of varying the size of the restriction with said restricting and separating means.

18. In a method as set forth in claim 17, the further improvement wherein said step of varying the size of the restriction comprises the step of progressively increasing the size of the restriction during at least said part of said drawing operation.

19. In a method as set forth in claim 16, the further improvement wherein said part of said drawing operation takes place during the initial part of said drawing operation.

20. In a method as set forth in claim 19, the further improvement wherein said step of restricting fluid flow does not restrict such fluid flow during the remaining part of said drawing operation.

21. In a method as set forth in claim 16, the further improvement wherein said step of restricting fluid flow comprises the steps of providing said restricting and separating means as a wall in said chamber which separates said chamber between said piston portions into said two chamber parts, and providing a flxed orifice through said wall interconnecting said chamber parts together.

22. In a method as set forth in claim 21, the further improvement comprising the step of interconnecting said chamber parts together with a one-way flow device to facilitate return of said ram to its non-drawing position relative to said fluid chamber.

23. In a method as set forth in claim 16, the further improvement wherein said step of restricting fluid flow comprises the steps of providing said restricting and separating means as cooperating surfaces on said piston portions of said one draw member and said ram which separate said chamber between said piston portions into said two chamber parts, and interconnecting said chamber parts together by the spacing between said surfaces to provide said restricted flow.

24. In a method as set forth in claim 23, the further improvement comprising the step of interconnecting said chamber parts together with a one-way flow device to facilitate return of said ram to its non-drawing position relative to said fluid chamber.

25. In a method as set forth in claim 23, the further improvement comprising the steps of disposing said piston portion of said ram within said piston portion of said one draw member, defining said surface of said rarn in the form of a spool, and forming said surface of said one draw member as a ring telescoping with said spool during at least said part of said drawing operation.

26. In a method as set forth in claim 25, the further improvement comprising the step of forming said spool with a tapering surface to provide for a progressively increasing in the size of the restriction between said spool and said ring during at least said part of said drawing operation.

27. In a method as set forth in claim 25, the further improvement comprising the step of forming said spool with an outer cylindrical surface disposed coaxial with said ring during the entire telescoping relation therebetween, and forming at least one tapering groove in said cylindrical surface to provide for a progressively increasing in the size of the restriction between said spool and said ring during at least said part of said drawing operation.

28. In a method for drawing an article from a blank of material disposed between cooperating draw members and being drawn therefrom by a movable rarn moving relative to said draw members and with a single fluid chamber receiving piston portions of one of said draw members and said ram whereby relative movement between said fluid chamber and said one draw member in one direction causes the blank drawing movement of said ram by the fluid action between said piston portions in said chamber, the improvement comprising the step of providing restricting and separating means on at least one of said piston portions located in said chamber causing said fluid to create a force on said piston portion of said one draw member greater than the force that would be created on said piston portion of said one draw member by the resistance of said blank to the drawing action of said ram thereon at least during part of the drawing operation of said rarn on said blank.

30. In a method as set forth in claim 28, the further improvement wherein said step causing said fluid to create a force on saidone piston portion of said one draw member comprises the step of varying the force on said piston portion of said one draw member during said part of said drawing operation.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3890819 *Jul 25, 1973Jun 24, 1975Centro Speriment MetallurgApparatus for deforming sheet metal blanks by fluid pressure
US4581915 *Jul 27, 1984Apr 15, 1986Reynolds Metals CompanyHydraulic cup holder
US4796453 *Jun 18, 1987Jan 10, 1989Karl HehlHydraulic element and drawing die assembly
EP0191802A1 *Jul 29, 1985Aug 27, 1986Reynolds Metals CoHydraulic cup holder.
EP0278062A2 *Oct 29, 1987Aug 17, 1988ALFONS HAAR Maschinenbau GmbH & Co. KGApparatus for deep-drawing sheet metal sections
EP0333052A2 *Mar 10, 1989Sep 20, 1989Karl HehlDrawing apparatus for shaping sheet metal blanks
Classifications
U.S. Classification72/347, 72/350
International ClassificationB21D22/22, B21D24/14, B21D24/00, B21D22/20
Cooperative ClassificationB21D24/14, B21D22/22
European ClassificationB21D24/14, B21D22/22