US2369260A - Tube drawing apparatus - Google Patents

Description

Feb. 13,1945. 'R E SLATER 2,369,260

' TUB R'AWING APP Filed March 7, 1944 S'Sheets-Sheet 2 vili; u

I INV OR RAEQMUN ELATER Patented Feb. 13, 1945 UNITED sTATEs PATENT oFFlcE TUBE DRAWING APPARATUS Raymond E. Slater, New Rochelle, N. Y., assignor u to Remington Arms Company, Inc., Bridgeport, Conn., a corporation of Delaware Application March 7, 1944, Serial No. 525,346

13 Claims. '(Cl. 20S- 4) by way of example directed to the drawing of cartridge case shells, which in the course of manufacture are subjected to a series of drawing, annealing, and trimming operations, and which from their nature require the highest precision standards, both from the standpoint of dimensions and metal characteristics. It is also of the greatest importance'that the drawn tubular article be protected against damage to its wall, such as galling, excessive abrasion, and strain of the metal, and also that the drawing tool and the stripper parts be protected from such galling and 'excessive abrasion. In the' case of the shell, such damage may extend to a portion of the finished product thereby creating a potential point of failure, and in the case of the tool and stripper surfaces, such damage may result in producing corresponding damage to the shells engaged therewith.

The usual type of stripper consists of a plurallty of segments, usually three, disposed within an internally tapered ring or fixture, the segments being provided with an opening having a ledge surface adapted to be engaged over ther edge of the drawn article after it has passed through the forming die and to be held `in contracted relation about the punch through the upstroke of the punch in the tapered ring, the shell being thus stripped from the punch. The segments have lateral opening and closing movement, opening laterally to allow the article on the punch to pass through the stripper, and closing laterally to dispose the ledge above the end of the article. As the diameter of the opening above the ledge and which engages about the punch is of smaller radius than the radius of the article, the outward lateral movement of the segments causes the end corners of the arcuate ledge surfaces of the respective segments to en-` gage the surface of the article while the arcuate edge of the ledge between these end corners is arched over the surface of the article, and consequently there is a tendency to gall or abrade the surface of the article, particularly where there is excessive frictional resistance as the article is passed through the stripper.

It is an object of the present invention to provide stripper means wherein the several segments are rockably supported to rock downwardly as the article is forced therethrough, so that the ledge surfaces are rocked outwardly away from the surface of the article to prevent any possibility of abrasion through contact of these edges with the article. It is furtherV proposed to provide an entrance surface above the ledge adapted to substantially conform to the diameter of the article, as the segments are rocked downr wardly through the passage of the article through the stripper.

A further object is to provide a stripper means wherein a more positive stripping action takes place through the cooperation of the stripper segments with the tapered ring, and to this end it is proposed to provide unlike angles -upon the segments and the tapered ring, whereby the segments are caused to have slightupward rocking movement during the withdrawal movement of the punch, causing the segments to engage against the wall of the article below the ledge, and with increasing force as there is increase in the upward thrust of the article upon Vthe ledge.

In practice this engaging point is in the end portion of the shell which is subsequently trimmed off and the clamping action of the stripper is such as to prevent the possibility of damaging strain being created in the :metal of the shell during the upstroke of the punch.

With the above and other objects in view em- Ibodiments of the invention are shown in .the accompanying drawings, and these embodiments will be hereinafter more fully described with reference thereto, and the invention will be nally pointed out in the claims.

In the drawings- Fig. 1 is a vertical sectional view, partially in side elevation, showing the punch with a cartridge case sh'ell engaged thereon at the beginning of the drawing operation and before engagement of the shell with the stripper means, the latter being shown in its normal contracted rest position.

Fig. 2 is a. fragmentary horizontal sectional view, taken along the line 2-2 of Fig. l, showing the segmental stripper means in top plan.

Fig. 3 is a fragmentary vertical sectionalview, taken along the line 3-3 of Fig. 2.

Fig. 4 is a bottom plan view of the segmental stripper means in its normal closed position and removed from the die.

Fig. 5 is a fragmentary vertical sectional view, showing an advanced position of the punch,

wherein the shell being drawn is engaged with the stripper means.

Fig. 6 is a fragmentary horizontal sectional view, taken along the line 6`8 of Fig. 5, showing the stripper means in bottom plan as engaged by the shell.

Fig. 'l is a fragmentary vertical sectional view, showing the completed drawn shell disposed beneath the stripper means at the completion of the d'ownstroke of the punch.

Fig. 8 is a fragmentary vertical sectional view, showing the punch partially withdrawn from the drawn shell during the upstroke of the punch.

Fig. 9 is a plan view of the three segments making up the stripper means at a point in their manufacture preparatory to having the opening through the stripper ground to its finished shape according to the invention.

Fig. 10 is a vertical sectional view taken along the line Ill-I of Fig. 9, and showing in dotand-dash lines the relative position of a finish ing grinding tool, or the like, as it engages the stripper opening to produce the finished surface thereon.

Fig. 11 is a plan view of the segmenttal parts of the stripper means as shown in Fig. 9, and showing the finishing tool engaged therein.

Fig. 12 is a vertical sectional view, taken along the line I2-I2 of Fig. 11, showing the finished segments, the finishing tool being disengaged therefrom.

Fig. 13 is a fragmentary vertical sectional view, partially in elevation, of a modified form of stripper means according to the invention.

Fig. 14 is a fragmentary vertical sectional view, partially in side elevation, of another modified form of stripper means according to the invention.

Similar reference characters indicate corresponding parts throughout the several figures of the drawings.

Referring to the drawings, the tube drawing apparatus, of the punch and die type illustrated by way of example in the present disclosure, comprises a die holding block I0 provided with a downwardly extending cylindrical pocket II, in the lower portion of which is engaged a stripper sleeve or ring I2 and in the upper portion of I which is engaged a drawing die I3 of conventional type. the base of the block being provided with a central opening I4, disposed axially of the opening of the sleeve I2 to allow passage of the drawn along radial planes and being normally contracted into closed position by means of an elastic closing ring I9, of coiled spring wire, rubber, or the Ilike, engaged in'a circumferential groove 20 in the outer sides of the stripper segments. In the normal closed position of the stripper, as shown in Figs. 1 to 4, the contacting end surfaces 2| of the segments are disposed in radial planes, the upper surfaces 22 are in a at horizontal plane, and the outer peripheral surface 23 is in the form of a frustum ora cone, preferably at a relatively steep angle. shown for example as 15. Angular clearance cut-outs 24 are provided upon the end surfaces oi' the segments to allow clearance gaps across which the elastic holding ring I9 extends between the segments. The under surface of each of the segments is provided at its outer edgel portion. with a flat supporting surface 25, parallel to the upper surface of the segment, and with an inclined surface 26 extending inwardly from the surface 25 to the inner periphery of the segment, this inclined surface adapted to permit downward rocking of the segment about the straight edge between the surfaces 25 and 26 as a fulcrum, and as will presently more fully appear. While the inclined surface 26 may be at any desired relative angle, the angle shown i .tion 21 along an arcuate line 32, calculated as constituting a. circular outline in the downwardly rocked position of the segments with their lower inclined surfaces 26 disposed in a horizontal plane. This circular outline corresponds substantially to the cylindrical outer surface of the drawn shell as it is forced downwardly through the stripper, the edge of the ledge 28 disposed beneath this arcuate line, and which has a diameter in the normal clos'ed position of the stripper slightly larger than the diameter of the punch and smaller than the diameter of the drawn shell. being rocked outwardly out of contact with the surface of the shell during its downward passage therethrough, so that there is no possibility of the sharp edge of the ledge or its end comers abrading the surface of the shell.

In order to understand fully the formation of the surface of the passage through the stripper the method of grinding the passage is illustrated in Figs. 9 to 12. As shown in Figs. 9 and 10 the passage is provided above the edge of the ledge 28 with the cylindrical surface 3i having its upper edge 32* parallel to the edge of the ledge and olf the same diameter, so that in the rocked position. with 'the lower inclined surfaces 26 of the segments resting upon a flat horizontal support, the edge 32' is disposed inwardly with respect to the edge of the ledge. It will be seen from the plan view in Fig. 9 that in this rocked position the edges 28 and 32B of the segments do not form a circle but Vform a clover-leaf shape. With the segments supported in this rocked position in a suitable fixture a suitable finishing tool 33 is engagedv in the passage through the segments, as indicated by the dot-and-dash lines in Fig. 10, the diameter of the tool being calculated as corresponding substantially to the outside diameter of the drawn shell to be engaged withl the stripper. This tool is operated to grind the passage,

resulting in cutting away portions of the entrance surface 21 and also preferably cutting back slightly the end portions of the edge of the ledge 28, thus producing the arcuate line 32 between the vcylindrical surface 3| and the entrance surface 21 and providing cut back clearance corners at the ends of the edge of the ledge of each seg ment. 'I'hus the stripper in the downwardly aa'eaaoo rocked position of its segments presents a passage corresponding substantially to the surface of the shell while the smaller radius semental edges 0I the ledge are entirely free from abrading con-A The opening 34 through the stripper ring i2 is in the form of a frustum of a cone tapering .tact therewith.

. 3 the invention-in which :ne lower sin-facessi of thesegments'of the are in anat plane parallel to their uppersurfaces, the base of the pocket l-I being provided with a downwardly and inwardly inclined dished portionV Il Vhaving an outer diameter less than that of the stripper, thus inwardly fromthe bottom to the top of the ring, Y

the opening being provided' at 0its lower end with a clearance angle portion 35, inclined-ata relatively greater angle than the inclination offtheV opening 3l. The angle ofthe opening 34 is calculatedl as being a slightly smaller angle than the angle of the tapered peripheral surfaceof `the segmentalstripper, the angle shown for example as being 14, or 1 -less than the 15 angle of the taper of the stripper. The purpose of the unlike angles is to permit of a lslight upward rocking movement of the stripper elements during the upstroke of the punch to facilitate the removal of the shell from the pun, as will presently more fully appear bodiment Y `v providing a clearance in which the seg-gv ments of the strlppermay rock` downwardly as `the drawn shellis passed therethrough in substantially the same manner as in the rst emrn ing. 14 there is shown Lof the invention in which a spacer ring ll is providedinthelbase of the pocket ",beneath the ring l2 and extending beneath the outer marginalportion of the bottom of the stripper, the

stripper having a nat lower surface 36. similar to the stripper shown in pag.13. This ring sup'- In operation, the punch-with the' cartridge' case shell A thereon is moved downwardly through the die; the wall. of the shell being drawn between the punch and the die to a wall thick'- trance portion are of substantially circular outline corresponding to the cylindrical outlineof the shell. At the same time the sharp edge of the ledge 28 is rocked outwardly, so that it is entirely free of contact with the downwardly moving shell, and hence there is no possibility of galling or abrading its surface. As the drawing of the shell is completed through the die and its upper edge carried below the stripper. the

stripper contracts to dispose the ledge 28 above the upper edge of the shell, as vshown in Fig. '7, wherein is illustrated the position of the punch and stripper at the completion of the downstroke of the punch. In this position the stripper rocks upwardly to its normal position. As the punch starts its upstroke, the mouth edge of the shell is brought into engagement with the ledge 28 and the stripper is carried upwardly izo-engage its tapered peripheral surface with the tapered opening 34 of the stripper ring, the unlike angles of the opening and the stripper causing' the stripper segments to tilt upwardly slightly, as shown in Fig. 8, causing the lower edge of the outwardly offset lower cylindrical portion 29 of the passage through the stripper to grip upon the outer surface of the shell slightlv below. its upper end. This gripping action takes place at each 120, point of the edge midway between the ends of each segment. Increase in pressure upon the stripper ledge increases the pressure upon the 120 points of contact. and hence effectually holds the shell as the punch is withdrawn without producing excessive metal strain lengthwise of the shell. and such as might occur when excessive pressure is exerted upon the end of the shell. particular-lv in the case of an uneven or scalloped ports the outer marginal portions of the segments while providinga clearance space beneath thel inner portions, thus permitting the segments i to rock downwardly as the drawn shell is passed therethrough, in substantially the same manner as the other embodiments of the invention.

The form of the invention illustrated in the drawings and ydescribed herein is typical'and il lustrative only, and it is evident that the invention is capable of embodiments in other forms. all falling within the scope of 'the appended claims. which are to b'e broadly construed.

What is claimed is:

l. In a drawing punch and die apparatus. stripper means comprising a'sectional stripper element including a. plurality of circumferentiallyg arranged stripper members adapted toengage about suhstantiallv the entire circumference of the punch adjacent themouth edge of the drawn arti^le. said segments having a substantially continuous circumferential ledge adapted to be 40 disposed in opposition to the mouth edge-of the edge. As the punch is withdrawn from the shell v upward pressure upon the stripper ceases and it contracts and drops to its normal position.

In Fig. 13 there is illustrated a modilled form of drawn article, said members being rockably mounted to move the edge of said ledge out of en- "agement with the surface of the drawn article ssiug therethrough.

2. In a draw-Incr punch and die apparatus. stripper means comprising a sectional stripper element including a plurality of circumferentially arranged stripper members adapted to engage aboutl the 'punch adiacent the mouth edge of the drawn article and having a circumferential ledge adapted to be disposed in opposition tol the mouth edge of the drawn article. said members each having a fwlcrum support at its under side per- `nfuittiner rocking movement thereof to move the edge of said ledge out of engagement with the surFace of the 'drawn article passing therethrough.

3. In a drawing punch and die apparatus,`

stripper means comprising a sectional stripper element including a plurality of circumferentially arranged stripper members adapted to engage about the punch adjacent the mouth edge of the drawn article and having a circumferential ledge adapted to be disposed in opposition to the mouth stripper including a plurality of circumferentially another modified form arranged segment stripper members adaptedx'to engage about substantially the entire circumference ofthe punch adjacent'the mouth edge of the drawn article, said segments havingv a substanably mounted i'or rocking movement in the direction of movement of the punch as the. article' ascaaeo mouth edge of the drawn article, means to yieldably hold said segments in contracted assembled relationship, said segments defining a passage including an upper and a lower portion joined by a stripping ledge adapted to be disposed in opposition to the mouth edge of the drawn article,

l ythe passage below said lledge being substantially is passed therethrough whereby the edge of said f ledge is moved out of engagement with the surface of the article passing therethrough, and

holder ring means to positively constrict saidA segment members duringV the withdrawal rocation of the punch. Y

5. In a drawing punch and die apparatgis, stripper means comprising a sectional segmental recipstripper element having an axial opening there-. through for receiving the punch and drawn article thereon, and including aplurality of circumferentially arranged segment strippermembers adapted to engage about the punch adjacent the mouth edge of the drawn article, means to yieldably hold said segments in contracted assembled relationship, said segments defining a passage including an' upper anda lower portion joined by a stripping ledge adapted to be disposed in opposition to the mouth edge of the drawn article, the passage below said ledge being substantially the diameter of the drawn article to engage about it, said segment members being rockably mounted for rocking movement in the direction of movement of the punch as the article is passed therethrough whereby the edge of said stripper ledge is moved out of engagement'with the surface of the article passing therethrough, and holder ring means to positively constrict said segment membersduring the withdrawal recip- 'rocation of the punch.

6. In a drawing punch and die apparatus. stripper means comprising a sectional segmental stripper element having an axial opening therethrough for receiving the punch and drawn article thereon, and including a plurality of circumferentially arranged segment stripper members adapted to engage about the punch adjacent the mouth edge of the drawn article, meansto yieldably hold said segments in contracted assembled relationship, said segments defining a passage including an upper and a lower portion joined by a stripping ledge adapted to be disposed in opposition to the mouth edge of the drawn article, the passage below said ledge being substantially the diameter of the drawn article to engage about it, and the passage above said ledge being substantially the diameter of the punch adjacent the edge of said ledge and including an upwardly divergent entrance portion, said segment members being rockably mounted for rocking movement in the direction of movement of the punch as the article is passed therethrough whereby the edge of said stripper ledge is moved out of ensagement with the surface of the article. passing the *diameter ofthe `drawn article to engage about it, and the 'passage above said ledge being substantially the diameter of the punch adjacent the edge of said ledge and including an upwardly divergent entrance portion having an article engaging surface spaced above the edge of said ledge and denning in a rocked position of said segments an opening of circular plan outline substantially conforming to the outer surface of the drawn article. said segment members being rockably mounted for rocking movement in the direction of movement of the punch'as the article is passed therethrough whereby the edge of said stripper ledge'is moved out of engagement with vthe surfaceof the article passing therethrough, and holder ring means to positively constrict said segment members during the withdrawal reciprocation of the punch.

8. In a drawing .punch and die apparatus, stripper means comprising a sectional segmental stripper element'having an axial opening therethrough for receiving the punch and drawn article thereon, and including a plurality of circumferentially arranged segment stripper members adapted to engage about the punch adjacent the mouth edge of the drawn article, meansto yieldably hold said segments in contracted assembled relationship, said segments defining a passage article engaging surface spaced above the edge of said ledge and deiining in a rocked position of said segments an opening of circular plan outline substantially conforming to the outer surface of the drawn article. the surface of the passage between the edge of the ledge and said article engaging surface being of corresponding radius to the radius of the edge of said ledge,

said segment members being rockably mounted Y for rocking movement in the direction oi' movement of the punch as the article is passed therethrough whereby the edge of said stripper ledge is moved out of engagement with the surface of the article passing therethrough, and holder ring means to positively constrict Asaid segment members lduring the withdrawal reciprocation of the punc 9. In a drawing punch and die apparatus, stripper means comprising a sectional segmental stripper element having an axial opening therethrough for receiving a punch and drawn article thereon, and including a plurality of circumferentially arranged segment stripper members adapted to engage about the punch adjacent the mouth edge of the drawn article, means to yieldably hold said segments in contracted assembled relation, said segments deilning a passage including a stripping ledge adapted to be disposed in oppontion to the mouth edge of the drawn article, the exterior surface of said contracted assembledsegmentsbeinginthefonnofatruncated 10. In a drawing punch and die apparatus,V

stripper means comprising a sectional segmental stripper element having an axial opening therethrough for receiving a punch and drawn article thereon, and including a plurality of circumferentially arranged segment stripper members adapted to engage about the punch adjacent the mouth edge of the drawn article, means to yieldably hold said segments in contracted assembled relation, said segments dening a passage including an upper and a lower portion joined by astripping ledge adapted to be disposed in opposition to the mouth edge of the drawn article, the passage below said ledge being substantially the diameter of the drawn article to engage about it, the exterior surface of said contracted assembled segments being in the form of a truncated cone, and holder ring means having an opening in the shape of a truncated cone for cooperation with said segments and inclined at an unlike angle to the angle of the truncated cone surface of said stripper segments, whereby during withdrawal reciprocation of the punch and relative axial movement between the assembled segments and the holder ring the unlike angles cause the segment members to tilt upwardly at their inner l peripheries relatively to their normal contracted position to clamp the lower segmental ends of saidpassage below said ledge about said article.

11.k In a drawing punch and die apparatus, stripper means comprising a sectional segmental stripper element having an axial opening therethrough for receiving a punch and drawn article thereon, and including a plurality of circumadapted to engage about the punch adjacent the mouth edge of the' drawn article, means to yieldably hold said segments in contracted assembled relation, said segments dening a passage including a stripping eldge adapted to be disposed in opposition to the mouth edge of the drawn article, said segment members being rockably mounted for rocking movement in the direction of movement of the punch as the article is passed ferentially arranged `segment stripper members therethrough whereby the edge of said stripper ledge is moved out of engagement with the suri face of the article passing therethrough, the exterior surface of said contracted assembled segments being in the form of a truncated cone, and holder ring means having an opening in the shape of a truncated cone for cooperation with said segments and inclined at an unlike angle to the angle of the truncated cone surface of said stripper segments, whereby during withdrawal reciprecation of the punch and relative axial movement between the assembled segments and the holder ring the unlike angles cause the segment members to tilt upwardly at their inner peripheries relatively to their normal contracted position.

12. In a drawing punch and die apparatus, a holder block having a pocket therein, stripper means disposed in said pocket comprising a sectional stripper element including a plurality of circumferentially arranged stripper members adapted to engage about substantially the entire circumference of the punch adjacent the mouth edge of the drawn article, said segments having a substantially continuous circumferential ledge adapted to be disposed in opposition to the mouth edge of the drawn article, said pocket having in its base a downwardly and inwardly inclined clearance recess disposed beneath said stripper members inwardly of their outer periphery and permitting downward rocking movement of the inner peripheries of said stripper members. to move the edge of Vsaid ledge out of engagement with the surface of the drawn article passing therethrough'.

13. In a drawing punch and die apparatus, a holder block having a pocket therein, stripper means disposed in said Docket comprising a sectional stripper element including a plurality of circumferentially arranged stripper members adapted to engage about substantially 'the entire circumference of the punch adjacent the mouth edge -of the drawn article, said segments having a substantially continuous circumferential ledge adapted to be disposed in opposition tothe mouth edge of the drawn article, and a spacer ring disposed in the base of said pocket beneath the outer :marginal portion of the under side of said stripper element permitting downward rocking movement of the inner peripheries of said stripper members to move the edge of said ledge out of engagement with the surfacev of the drawn ar. ticle passing therethrough.

RAYMOND E. SLATER.

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