US2580454A - Combination drawing die and stripper - Google Patents

Description

Jan. 1, 1952' c. w. MUSSER 2,580,454

COMBINATION DRAWING DIE AND STRIPPER Filed March 29, 1946 s Sheets-Sheet 1 Fignl 20 I I A .Fi S- E.

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Jail. 1, 1952 c, w, ussgn 2,580,454

COMBINATION DRAWING DIE AND STRIPPER I x 26 M 2/6 "mm I g L26 J' HILvp [LVVALTUN MU Jan. 1, 1952 c, w, ss R 2,580,454

COMBINATION DRAWING DIE .AND STRIPPER Filed March 29, 1946 3 Sheets-Sheet 3 [lVVAIJ-UN M USSEFQ,

Patented Jan. 1, 1:952

COMBINATION DR STRIPP AWING DIE AND Clarence Walton Musser, Philadelphia, Pa. Application March 29, 1946, Serial No. 658,188 9 Claims. (01. 113 50) (Granted under the act of amended April 30, 1928;

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

My invention relates to the production of mechanical draw pieces by conventional punch and die techniques and it has special reference to means for stripping a draw piece (such as an ammunition primer cup) from the punch after it has passed through a drawing die.

Broadly stated the object of my invention is to provide a die which is capable of performing a dual function of drawing cup-like pieces and thereafter positively stripping them from the draw punch.

A more specific object is to eliminate the need for separate stripping means in supplement to normal punch and die drawing apparatus.

Another object is to provide means for stripping draw pieces from the punch in cup drawing assemblies having no space for inclusion of conventional strippers in addition to the draw die. I

In practicing my invention, I attain theforegoing and other objects by providing in a uniquely constructed single unit the combination of a die for drawing cup-like pieces, typified by ammunition primer cups, and means thereafter effective for positively stripping the draw pieces from the punch. One preferred form of this apparatus specially adapted for the. processing of primer cups will herein be described and illustratively shown by the accompanying drawings wherein:

Fig. l is a sectional view showing a blank which has been preliminarily cupped emerging from a blanking and cupping die preparatory to being forced by the draw punch down through my novel combination die and stripper;

Fig. 2, representing an advanced stage of the Fig. 1 operation, shows the partially formed primer cup passing through my unique dual acting die and stripper;

Fig. 3 is a smiliar view which shows the head of the fully drawn cup being flattened by contact with a backing punch;

Fig. 4 progressively represents how the drawn cup returns to contact an underside of my new type drawing die as the draw punch is withdrawn upward;

Fig. 5 further illustrates the upward withdrawal of the draw punchand the unique cocking action of my floating against; l

Fig. 6 shows the finished primer cup, which was stripped from the draw punch by contact dual purpose die. which causes the draw piece to abut there- March 3, 1883, as 370 0. G. 757) l l 2 with the under side of 5, being evictedfrom the machine; l r

Fig: 6 parallels the Fig. 5 view with the exception that a primer cup which has failed to strip on the bottom edge of the die is shown wedged within the bore of the cocked floating die to thereby become positively stripped from the draw punch;

Fig. 8 is a bottom view of the combined floating die and stripper which is shown mounted in a die-holder in Figs. 1 to 7, illustrating the portion ofthe dies under surface which is specially ground obliquely to the central bore axis of the die;

Fig. 9 resembles the foregoing sectional representations but includes an alternate form of my superior dual acting die and stripper unit.

Conventional primer cup drawing apparatus and method manufacturing-cartridge cases, primer cups and the like.

In the course of drawing metal tubes or cups through a die, the drawn objects tend to adhere to the draw punch. It then becomes necessary to remove, or as is popularly termed strip," the draw piece from the punch.

In deep drawing, as exemplified by cartridge cases, special stripping devices have been incorporated within a drawing mechanism assembly in order to accomplish this removal of the draw piece. An example of'one such conventional stripping means is represented by Patent 2,327,936 which was issued on August 24, 1943 to Raymond E. Slater for Tube Drawing Apparatus.

In certain drawing operations well typified by primer manufacturing procedures, it is sometimes impractical to use strippin means in supplement to the normal drawing dies because of a lack of suificient space in the mechanism by which the draw piece is fabricated. In lieu of such separate stripping devices, the prior art has depended upon the draw die itself to effect the required strippingaction. I

As the drawn object returns upward adhering to the draw punch, it is expected that the draw piece, relieved of the stress exerted by the die as the primer cup or other object is being passed therethrough, will expand to a. suiliciently large overall diameter to thereby cause it to contact the bottom edge of the draw diescentral bore.

the floating die in Fig.

become jammed.

for stripping the draw piece, extreme care must.

be exercised to maintain the sharpness of the bottom edge and the diameter of thelowermost portion of the draw dies central bore. If this lower opening of the central bore is permitted to become bellmouthed, or its bottom edge rounded, suflicient resistance may not be exerted on the draw piece to positively strip it from the punch.

In cases where reliance is placed upon-a stationary drawing die to strip the draw .piece,'as

in Patent 2,379,450, trouble ofttimes arises when the sidewalls of the drawn object have "failed to spread sufficientlyto assure contact with they diewhen the frictionally held drawpiece returns upward along with the draw punch. This failure results in the finished draw piece penetrating and occupying space within the draw die and thereby interfering with the succeeding drawing operation, consequently causing the mechanism to The described lack of positive. strippingaction in the prior art devices has caused a distinct need for my herein disclosed improvement.

and has made possible trouble-free manufacture of even the-very smallest ammunition primer cups and the like.

My improved combinationdie and stripper My unique dual-actingdie can be made quite easily from available bar stock or by altering the form oi a conventional ring-shaped drawing die.

First, the entire top or input surface is machined at an oblique angle (see Figs. 1 to 7) with respect to the vertical axis of the dies central bore. Next a central portion of the dies under or output surface including the area surrounding the central bore (see Fig. 8) thereof,-is likewise machinedobliquel and parallel to the just described machined upper surface. The result achieved is depicted by-the;.nove1 .die form shown at 16 in Figs. 1 to 8.

The thus designed dual purpose'die I5 is placed in -a conventional die holderll in the customary manner. In the arrangement shown by the accompanying illustrationsthe assembly includes a conventional blanking and cupping die 18. also' maintained withinthe die holder 11, both dies being held therein by the die holder plate l9. This die holder plate I9 is fastened to the die holder !1 by screws (not shown in the illustrated sectional views) For purposes of completeness of illustration Fig. 1 of the drawings shows a blanking punch 20 whichstamps out blanks from the stock being fed through channel 26 indie holderplate I9. The complete operation, represented here, only in part, is best shown and thoroughly described in my earlier mentioned Patent 2,379,450 for PrimerManufacturec There I have described themanner inwhich, by means of a double acting press, one revolution of a crankshaft (not here shown) blanks andforms the cup there represented in Fig. 1 by 21A.

My. herein disclosed improvement comprises As will now be made clear, my unique combination dieand positive acting stripper fulfills this need:

the unique die [6 which may readily be substituted for prior art sizing or redrawing dies (see reference character 3 in Patent 2,379,450) to effect immediate improvement in the conventional manufacture of primer cups and similar objects. For a thorough understanding .of this novel dies function, the following description need, therefore, only be confined to the essential parts coacting therewith.

. Operationof my unique combination die and stripper by the downward force of draw punch 30. The

drawn cup 27A then enters the central bore 32 "of die l6 which is aligned directly therebeneath and whose'inne'r side walls parallel the vertical axis of the draw punch 30.

Continued downward movement of punch -3| from the Figal' position forces the cupped draw piece 27A through die lli to take the form 'shown at 213 in Fig. 2. In the illustrated mechanism, which is" designed ior manufacturing fiat bottom primer cups, punch 30. carries the draw pieces into contact with a backing punch 34,-asshown in Fig. 3, giving thedrawn cups the final shape represented by 270. V a

With continued 'rotation of: the machines crankshaft: (not here shown-) dr'aw punch iifl is made to'ascend; Insodoing the completed draw piece 270, beingtrictionally held to: draw punch 30, also" israisedupward;v If the side walls of the completed draw piece 27C have spread. apart sufficiently,'as' n'ormally occurs when a cupis relieved. from the stress of being'for'ced through a drawing die, this raisingof the-drawn cup will bring it into contact-with the' unde'r side of the die l6, asshown-in Fig. 4. 1

Such contact will generally cause the drawn cup Z'ICJto be stripped-fromdraw punch -30'-even by a conventional draw die, and'the-same-holds true with my improved'combination die ands'tripper 16. However,:a1thou'gh' theresultant stripping action :is similarn-innboth the old: and the new: types, the manner of operation is different. Whereas,imoreovcrgthe conventional and my new dies both can stripdrawn cups under the just described conditions, it will later bebrought out that my improvement will function-in certain cases where :th e prior art device 'fails" to operate properly.

As' showninFig. 5'; when my novel die i6 is contacted by the.. asc'ending drawn cup ZIC it is cocked upwardly 'untilrestrained by the immovable cupping die I8. Sin'ce the-draw piece 270 is. then prevented from further asc'ension, the rising: punch-3.01 is withdrawn free of engagement therewith. Thethus stripped draw piece is then ejected from the machine by any-conventional method such as by ab'last of air as-used in Patent 2 579,450 and here represented in the accompanying illustrations by the directionalarrows shown in Fig. 6. a

The superioritylofmy novel dual acting dieresidessi-n its abilityto strip cup shapedobiects that have failed to contact and be strippecliby the under side-0f the: draw 'die.- Theability to strip thoseadraw pieces which would normally return through a'conv'entional stationary type die gives to my noveldiethe' ability to act as a-completely positive stripper, unlike its predecessors in the art.

:Reference to. Fig. 'Zwill show the manner in which these undersized draw pieces 211) are stripped by my novel combination die and stripper IS. The drawn cup 21D is there shown to have penetrated up into die llis central bore 32 due to frictional adherence of the cup to the ascending punch 30. The draw piece, being of diameter approximately equal to the central bore 32 through which it was drawn, is caused to strike the side walls of that bore. Only very slight contact is necessary to cause die I6 to cock upwardly until it is stopped by the blanking and cupping die l8 as shown in Fig. 7.

The just described cocking action brings a portion of central bore 32's upper side wall and, diametrically opposite thereto, a portion of that bores lower side wall closer than normal to the draw punch 30. This inward movement of cen-- tral bore 32s opposing sidewalls with respect to the draw punch diminishes the cross sectional area of central bore 32 available for upward travel of draw piece 27D. The result is that an edge of the cup-like draw pieces open end becomes wedged against the inwardly protruding upper wall portion of die His central bore 32, while at the same time the opposite side of the draw piece is pinned against the lower wall portion of bore 32 which has moved in towards punch 30.

The higher up the drawn cup tighter it becomes wedged against the dies inner walls. This wedging action holds the draw piece as the ascending punch 30 is withdrawn therefrom. Once the draw piece is so released from the draw punch, die [6 drops down from its cocked Fig. 7 to the Fig. 1 position preparatory to receiving and acting upon another cupped blank 21A. Simultaneously draw piece 21D may be ejected as was drawn cup 210 in Fig. 6, if the draw piece is not wedged too tightly within the dies bore. If the draw piece remains wedged within the die, however, it is ejected by the next piece that is drawn through the die.

21D rises, the

Alternate form of my novel die and stripper It will be evident to those skilled in the art that my unique die and stripper unit may be used in somewhat different forms than heretofore shown and described, and in fact may be applied to other uses than in the manufacture of primer cups. One such substitute form is shown at ISA in Fig. 9 and will now be described.

To make this particular form of my improved dual acting die, the entire upper and lower surfaces of a conventional die (not shown) or bar stock material are ground parallel to each other. both at an oblique angle with respect to the vertical axis of the dies central bore. This grinding of the entire bottom surface, rather than merely grinding a portion surrounding the central bore 32A asin the method described for manufacturing my new type die l6, may possibly be a more preferable manner of practicing my invention for some sizes of dies than the earlier representation because it may be simpler to make.

To utilize this form of my improvement, however, a slight modification to die holder I1 is required, namely, an angularly inclined supporting shelf 38, which must be inserted or built into the die holder l1 and the die IBA keyed against rotation by some means as the pin 40 shown in Fig. 9. This shelf 38 enables the alternate design die IGA to assume the same relative positions as my first represented novel die l6 before and during the drawing operation, while still leaving the necessary room for the earlier de- Summary From the foregoing description and accompanying illustration it will have become evident that my improved combination die and stripper is capable of performing a dual fuction of drawing cup-like pieces and thereafter acting in a unique manner as a positive stripper to remove the draw piece from the drawn punch; that my invention has eliminated the need for separate stripping means in supplement to normal punch and die apparatus by which such cup-like pieces are made; and that I have provided means for stripping draw pieces from the punch in cup drawing assemblies having no space for inclusion of conventional strippers in addition to the draw die.

It will be evident to those skilled in the art that my improvement is not limited in its application to the manufacture of ammunition primer cups which is here shown an described for purposes of explanation, but may properly be utilized in other punch-and-die drawing operations without departing from the spirit and intent of the invention.

My inventive improvements are therefore extensive in their adaption and are not to be restricted to the specific form here disclosed by way of illustration. 7

I claim: a

1. In apparatus for forming cup-shaped tubular members, the combination of a .die holding structure comprising substantially parallel first and second interior wall surfaces spaced one from the other and having substantially coaxial openings extending therethrough, a reciprocable draw punch axially movable forwardly and backwardl through said holding structure openings, and a die positioned between said first and second wall surfaces with its input end on the first surface side and there so supported by said holding structure as normally to rest its discharge end surface against said second wall surface with the bore axis of the die coinciding with the draw punch axis whereby during each advancing stroke of said punch a cup blank forced forwardly through the die by the punch will be drawn into a. tubular member, the body of said die nearly filling the space between said first and second wall surfaces on one side edge of the die and tapering to a thinner section on the opposite side edge thereby freeing said thinner portion only of the die for limited backward travel which angularly tilts the die bore axis away from the drawn punch axis whereby during each backward stroke of said punch the open-end edge of said punch-carried tubular member in returning against the dies discharge end will tilt the die bore axis as aforesaid and thereby so block further backward movement of the tubular member as positively to strip same from the draw punch.

2. In apparatus for forming cup-shaped tubular members, the combination of a die holding structure comprising substantially parallel upper and lower interior wall surfaces spaced one from the other and having substantially coaxial openings extending therethrough, a reciprocable draw punch axially movable downwardly and upwardly through said holding structure openings, and a die positioned between said upper and lower wall surfaces with its input end uppermost and there so supported by said holding structure that when normallyzrestingfon said lower'wall surface before: and duringseachidown "stroke of" said draw be drawn into a tubular -member-,-the body :of.

said die nearly filling the -space between said 1 upperzan'd lower wall surfaces-ion oneside edge.

of the die and tapering to a lesser thickness on the opposite side edge thereby freeing said. thine her portion only of the die for limited upward travel which angularly tilts the die bore axis:

away irom: the draw: punch axis whereby during each return up stroke ofsaid punch the open-end edge-:ofsaid"punch carried tubular member in upwardlyzireturning.against-the dies lowerdise openingiin'said tubeholders baseya drawing die charge end will tilt the diebore axis aszaforesaid and thereby so; blockiurther upward movement of the tubular member as positively to strip samefrom the draw punch.

3. In a drawing punch and die apparatus, comhaving an upper input's'urface and'an opposed I I "lower output surfaceof which the entire upper surface is substantially oblique with respect to a bined'dierandstripper means comprising aread-m ily cocked ially therethrough rand'thaving parallel first and secondi surfaces which areoblique with respect to the Saidbores axis, a'holder'for said mem-- member having a bore extending axoutpu t sur'face is perpendicular to'-" the said 1 bore Jail? axis. 1

6. The combination of claim 4-in which the die is-essentially of axing-shaped construction having opposed first and second surfaces of which the first 1 surface-is substantially oblique 1 with respectto the axis of the dies bore and the secondsurface is perpendicular to said boreaxis except for an area'encompassing the --borewhich is parallel to said first su'rfacee '7. In apparatus for forming tubular-membersthe combination of a die-holder comprising. box-like structure formed of sidewalls and ahorizontal. base with a vertical openingthere through; a reciprocable draw-punch axially mov able downwardlyand upwardly through the the axis of the dies bore and the lower surface is perpendicular-to saidbore axis except for an i area encompassing the bore which is parallel to the dies uppersurface, the die being-movably I mounted insaid holder so that during downward movement of said punch the dies lower 'surholder for preventing lateral movement of said member without limiting its said cocking move merit. j i

i. in apparatus for forming a tubular mem= bers, the combination of: a die holder'compris ing abox-like structure formed of sidewalls and a basewithan opening therethrough; a reciproe (Y coincidence with'the drawpunchaxis, whereby cabledraw punch. axially movable through the opening in said holders base; a tube drawing die having an input surface and an opposed out- 7 put surface of whichithe entire input surfaceis substantially oblique with respect to the axis of the dies bore-and the output surface is perpendicular to'said bore axis except'for an area encompassing the bore which is parallel to the dies input surface, the die being movably mounted in said holder so that during movement of said punch in the direction of the holders base the dies output surface abuts against said holders base while the dies input surface is out of perpendicular to'the axis of the punch although the dies bore is -in axial coincidencewith the punch; whereby during-each stroke of said punch-in the direction of the holders base a tube blank-forced through the die will be drawn" out; and a plate-li'ke member having an opening ther'ethrough for admitting said punch and secured *to said holder so as to retain said die therein and yet provide room for the die to cook away from said holders base so that the dies bore axis is tilted out'of coincidence with the draw punch axis, whereby during ea-ch'stroke of said punch "away from said holders base the leading w edge of the punch-carried drawn tubular lmember-will contact :thedie and tilt its bore axis as aforesaid and thereby -so block further backward movement of the tubular memher as positively to strip same .from the draw punch.

face abuts against-said holders-basewith" the dies upper surface out of perpendicular to the axis of the punch but with the dies -bore '-in' axial coincidence" with thepunch; whereby dur-' ing each downward stroke of said pun-ch atube blank: forced through the die'will be drawnouty and a plate likemember having an opening therethrough for admitting said punch and se cured to said holder soas'toretain said die there 1 in and yet'provide room for the die to cock-'up-'- wardly so that -th'e dies bore axis tilted out of during each. upward stroke of said'punch the leading edge of the punch-carried drawn tubular member. will contact the die and tilt its bore ing in said'holdersbase; a first -tube drawing die having a first surface which issubstantially oblique with respect tothe axis of the dies bore and an opposed second surface which is perpendi-cular to said bore axis except for an area encompassing the. bore which is parallel to the dies first surface, the die being movably mounted in I said holder so that during movementof said i punch in'the directionIof the holder's base the dies second surface abuts against said holders base while its first surface is out of perpendiciular to the axis ofth e punch although the dies bore 15 in axial coincidence with the'punch,

I whereby during each 'stroke'of said pun-ch in 5. Theicombination of claim i in whichwthe die is essentially': of. a ring-shaped construction whose input 'surface is substantially oblique with respect to the axiso? the dies boreand whose the direction of the holdersbase atube blankwill be. drawn therethrough'; and a second tube drawing die having opposed first and second surfaces thelatter'of-which is perpendicula'rto the axis of the diesebore which 'is axially'aligned with said punoh,-the die being secured within said holder so thatits second surface confronts and serves to contain said first die therein and yet provide room for said first'die to cock away i from said'holders baseso that its bore axis is tilted ouli Of axial coincidence with the "draw" u P we y rineeach' stroke or said punch away irom said holder's base the leadin edge of the punch-carried drawn tubular memher will contact said first die and tilt its bore axis as aforesaid and thereby so block further movement of the tubular member as positively to strip same from the still moving draw punch.

9. In apparatus for forming tubular members, the combination of: a die-holder comprising a bx-1ike structure formed of sidewalls and a horizontal base with a vertical opening therethrough; a reciprocable draw punch axially movable downwardly and upwardly through the opening in said holders base; a first tube drawins die having opposed upper and lower surfaces of which the entire upper surface is substantially oblique with respect to the axis of the dies bore and the lower surface is perpendicular to said bore axis except for an area encompassing the bore which is parallel to the die's upper surface, the die being movably mounted in said holder so that during downward movement of said punch the die's lower surface abuts against said holders base with the die's upper surface out or" perpendicular to the axis of the punch but with the dies bore in axial coincidence with the punch, whereby during each downward stroke of said punch a tube blank will be drawn therethrough; and a second tube drawing die whose lower surface is perpendicular to the axis of the dies bore which is axially aligned with said punch, the die being secured within said holder so that its lower surface confronts and serves to contain said first die therein and yet provide room for said first die to cook upwardly so that its bore axis is tilted out of axial coincidence with the draw punch axis, whereby during each upward stroke of said punch the leading edge of the punch-carried drawn tubular member will contact said first die and tilt its bore axis as aforesaid and thereby so block further upward movement of the tubular member as positively to strip same from the draw punch.

CLARENCE WALTON MUSSER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 89,869 Kent May 11, 1869 2,345,857 Newell Apr. 4, 1944 2,379,450 Musser July 3, 1945 2,406,768 Hitt Sept. 3, 1946

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