US1995466A

US1995466A - Punching mechanism

Info

Publication number: US1995466A
Application number: US645557A
Authority: US
Inventors: Bishop Frank
Original assignee: Individual
Current assignee: Individual
Priority date: 1932-12-03
Filing date: 1932-12-03
Publication date: 1935-03-26
Anticipated expiration: 1952-03-26

Description

March 26, 1935.

F. BISHOP PUNCHING MECHANISM Filed Dec. 3, 1932 mnmmn 2 SheetsSheet l Dania: 1311572 0,17

March 26, 1935. F s op 1,995,466

PUNCHING MECHANISM I Filed Dec. 3, 1932 2 Sheets-Sheet 2 IIHII'HHIIIIIIHIIII grvue/wbo b 7 Frank 5215710}? 331g I 4 Patented Mar. 26, 1935 UNITED STATES 1,995,466 PUNCHENG MECHANISM Frank Bishop, Los Angeles, Calif. Applicationfiecember 3, 1932, Serial No. 645,557 14 Claims. ('o1.1c4 20) This invention relates to a punching mechanism and more particularly pertains to a, punch for forming metal rakes of the type commonly known as garden rakes. An object of the invention is to provide a mechanism for cutting from a flat strip of steel, of the proper width and thickness, two rake-head strips each of which includes a broad back and teeth having sharp points, and whereby the cuts in the strip of steel are made in a peculiar succession by the action of a plurality of punches and associated dies in a manner similar to that set forth in United States PatentNmnberlQQJll, issued January 8, 1878, to Elijah Sims, whereby two complete and separated strips of rake-heads are formed from a single strip of steel with the teeth of each of the rake-head strips formed in most part from material removed from between adjacent teeth of the other rake-head strip.

A particular object of the present invention is to provide a punching mechanism for forming strips of rake-heads in the above'stated fashion in such manner as to insure the formation of sharp points on the ends of the teeth and also insure formation of all of the rake-teeth on the strips of substantially corresponding sizes and contours.

Another object is to provide a punch of the above character which will so operate as to pre- 30 vent twisting of the teeth by lateral extensions on he punch and thereby obviate re-working of the teeth after punching of the strip.

A further object is to provide a punch which will enable formation of the teeth throughout a portion of the length thereof of a transverse width less than the thickness of the metal from which they are stamped.

Another object is to provide a construction in the punch whereby transverse displacement of 40 the teeth will be thereof. 7 g

A further object is to provide a means for insuring proper positioning of the strip to be punched on initially feeding it to the punching mechanism, together with means for retaining the strip in proper relation to the punches and dies during successive'punching operations. With the foregoing objects in. view, together with such other objects and advantages as may 50 subsequently appear, the invention resides in the parts and in the combination, construction and arrangement of parts hereinafter described and claimed, and illustrated by way of example in the accompanying drawings, in which:

Fig.1 is a view of the punching mechanism as prevented during punching Cit PATENT" OFFICE H seen in end elevation, showing the parts in their normal position with the punch retracted, portions being broken away to depict parts incross section;

Fig. 2 is a view in longitudinal section as seen '5 on the line 2-2 of Fig. 1, showing the parts as disposed with the punch member in a partly advanced position with the punches disposed as about to penetrate the strip; Y Fig. 3 is a plan view as seen on the line 33 10 of Fig. 1 illustrating thedies and their associated guides and stops;

Fig. 4 is a view in vertical section as seen on the line 4'4 of Fig. 2, showing the punch memher in its advanced or punching position and depicting a die as penetrating the strip; I

Fig; 5 is an enlarged section taken on the line 5-5 of Fig. 4 illustrating the manner in which contiguous rake teeth are held against lateral displacement and also held against twisting during the punching operation;

- Figs. 6, 7 and 8 are plan views of the die illustrating the manner of initially feeding the strip to the punching mechanism and showing the successive operations of forming the rake-head strips;

Fig. 9 is a plan view showing a fragmentary portion of the formed rake-head strips, showing the manner in which the rake teeth are formed by a series of successive cuts with the arrangement of punches and dies shown in the preceding views.

Referring to the drawings more specifically, A and'B designate generally the die member and the punch member, respectively, of a punch press, which members embody the features of the punching mechanism constituting the present invention.

The die member A includes a die-plate 10 which is secured to and supported on. a bedp1ate12 in a usual manner, as by bolts 13. The die-plate 10 is formed with a smooth fiat upper face and is provided with a pair

ofparallel upstandingflanges

14 and 15 on opposite upper margins thereof, the inner faces of which flanges project vertically at right angles to the top face of the die-plate 10 and constitute guides for directing a flat strip C of sheet metal longitudinally across the upper face of the die-plate 10; the upstanding inner faces of the flanges l4 and 15 being arranged to slidably contactthe edge margins of the strip C. i In carrying out the present invention, the dieplate 10 is formed with a pair of die-

slots

16 and 17 of peculiar arrangement and contour, and the punch member B is fitted with a pair of

punches

18 and 19 arranged to be extended into and withdrawn from the die-slots and formed with side and end margins to conform to the margins of the die-slots 16 and 1'7, as is common in punch and die construction. Since the

punches

18 and 19 have their side and end margins formed to conform to the margins of the die-slots only the formation and arrangement of the latter need be described in detail herein. J

The die-

slots

16 and 17 are elongated and extend longitudinally in the general direction of the width of the plate 10 between the flanges 14: and 15; the slots being of equal lengths with their corresponding end walls terminating in alignment with each other and spaced corresponding distances from the inner margins of the

contiguous flanges

14 and 15. l 'l The die-

slots

16 and 17 extend in angular relation to each other equi-distant on opposite sides -of.a verticalplane extending transversely of the die-plate lo midway between theends of the latter, whereby the ends of the die-slots adjacent the flange 14 are spaced apart a greater distance than the ends of the die-slots adjacent theflange 15. ,The intermediate portions'of the die-

slots

16 and 17 are in the form-of parallelograms that is with parallel opposite side margins,

while the end portions of the die-slots are extended laterally in opposite directions; the lateral extensions on the divergent end portions of the die-slots projecting outwardly away from each other, as indicated at,20 and 21 in Fig. and the lateral extensions onthe convergent end portions of the slots projecting inwardly toward each other, as indicated at 22 and 23. The lateral terminations of the extensions 20, 21, 22 and 23 aresubstantially semi-circular in outline, aefindicated at a, and the outer and inner walls-of the lateral extensions merge into the side walls of the intermediate portions of the die-slots on arcs, as indicated atb and c. v

The die-slots Miami 17, andalso their associated

punches

18 and 19, are spaced apart such distance that their inner margins will, on punching a pair of holes through the strip C, form the opposite side edges of a pair ofadjacent rake teeth of one rake-head strip, and their outer margins will form the confronting margins of a pair of alternate rake teeth of the other rake-head strip. y

On advancing the strip C over the die-plate between successive punching operations, a distance corresponding to the distance between the longitudinal centers of 'a pair of adjacent rake teeth to be formed on one rake-head strip, a-se ries of three of such steps or operations will effeet the formation of a continuous back and forth slot which will completely form two adjacent rake teeth on one side thereof and a single oppositely extending rake tooth on the other side thereof, and whereby repeated triple operations will separate the strip C into a pair of rake-head lengths D and E, as shown in Fig. 9, as will hereinafter be more fully described.

The mode of operation of punching the strip 0 to form the rake-head strips is substantially the same as that set forth in United States PatentNo. 199,111, above referred to, but I have found that merely employing the pair of punches and dies, as set forth in said patent, in punching a sheet metal strip of greater thickness than the transverse Width of the outer end portion of the rake teeth to be formed thereby, is impractical since the material constituting the rake teeth will be crowded sideways during the punching operation and at the same time will be twisted, thus resulting in deformation of the rake teeth such that the teeth of the rake-head will not be of uniform size and furthermore will require straightening and other treatment after completion of the rake-head strips.

' the die-slot 1.6, as shown in Fig. 3, which projections are arranged to protrude into a pair of adjacent slots cut by the punch 19 and die slot 17, andto engage opposite sides of the material of the strip C extending between said slots and from which is. to be cut a strip of material by the punch 18 and die-slot 16, as illustrated in Fig. 8.

The

projections

24 and 25 are here shown as comprising cylindrical pins slidably supported in sockets 26 formed in the die-plate 10; the pins being [normally arranged with their upper end portions normally projecting above the face of the die-plate under the urge of coil springs 27 disposed in'the sockets 26 and bearing between the bottom .walls of the sockets and the lower ends i of said pins, as particularly shown in Fig. 5.

A pair of

projections

24 and 25 are preferably provided, as shown, so as to form an abutment adjacent both the outer and the inner end portions of the rake teeth.

The punch member B embodies a stripper-plate 30 arranged to overlie the die-plate 10, which stripper plate is mounted for vertical movement relative toa punch supporting plate 31 affixed on a header 32 carried by a stem 33 of the punch press;.the stripper-plate '30 being mounted on the lower ends of a series of bolts 34 the shanks of which slidably extend through and are guided by openings 35 formed inthe plate 31. Interposed between the stripper plate 30 and the die supporting plate 31 is a resilient member 36 here shown as formed of rubber, which member yieldably opposes upward movement of the stripper plate 30'relative to the plate 31 and normally maintains the stripper plate 30 in its lowermost position relative to the plate 31. The heads of the bolts 34 are adapted to seat on the upper face of the plate 31 to limit downward movement of the stripper plate 30.

The stripper plate 30 is formed with a pair of

slots

38 and 39 located directly above the

dieslots

16 and 17, through which the lower ends of the

dies

18 and 19 project as shown in Fig. 2; the margins of the

slots

38 and 39 being formed to conform to and slidably contact the side and end faces of the punches l8 and 19.

vThe lower end portions of the punches are elongated vertically so as to permit of their being protruded through the

slots

33 and 39, through the strip C and into the die-

slots

16 and 17; the upper ends of

thepunches

18 and 19 being engaged in the plate 31 in a usual manner so as to be carried by the header 32 of the punch press. The punches are arched longitudinally on the lower ends thereof, as shown in Fig. 4, so that the end portions thereof will extend below the intermediate portion whereby the lateral extensions on the ends of the punches by reason of being protruded relative to the intermediate portions of the punches will effect severance of the web at the ends of formed prongs before severance of the webs intermediate the ends of the prongs is completed.

The stripper plate 30, and the manner of mounting same on the header 32, is old in the art and accordingly comprises no part of the present invention other than in association therewith, but in carrying out the invention the under side of the stripper plate 30 .isvformed around the margin of the slot 38 with a downwardly projecting rim 40, which rim .is adapted on-operation of the press to be brought to bear on the upper surface of the portions of the strip C overlying the portions of the die-plate 10 extending between the opposite side margins of the slot 16 and the

projections

24 and 25 so as to clamp the lengths of the metal of the strip C extending along the margins of the slot 16 against twisting during penetration of the punch 18 through the strip C and also withdrawal of the punch 18 from the strip C. 7

As a means for enabling proper positioning of the strip C on the die-plate 10 in effecting initial punching thereof, an abutment is provided on the die member for engaging the forward end of the strip, which abutment is here shown as comprising a slide bar 41 extending transversely through the flange 15, to the outer end of which is engaged a spring 42 whereby the slide bar will be normally disposed in a retracted position with its inner end disposed between the side margins of the flange the slide bar 41 being adapted to be manually advanced in opposition to the spring 42 so that its inner end will protrude beyond the inner face of the fiange 15, as particularly shown in Fig. 6. The slide bar 41 is arranged so that'the edge thereof presented toward the end of the strip C will serve as a stop for the latter at a point where the end portion of the strip C will overlie the die-slot 1'7 a distance slightly less than the transverse thickness of a rake tooth.

In the operation of the invention, a flat strip C of sheet-metal such ashot rolled steel of approximately one-fourth of an inch in thickness, of appropriate width andof any desired length, is initially positioned on the die-plate 10 between the

guide flanges

14 and 15 withthe forward end of the strip abutting against the slide bar 41 which has been advanced to project in front of the forward end of the strip C, as particularly shown in Fig. 6.

The punch member B is then operated in a usual manner to advance and retract the punches and to cause the punch 19 to penetrate the strip C along the margin of the die-slot 17 and thereby form a slot having the contour indicated by the dotted lines in Fig. 6, and designated as 1st cut, which slot forms, between one margin thereof and the adjacent end of the strip C, a rake tooth designated as 1st tooth. The slide bar 41 is then retracted and the strip C advanced to a position where the slot formed by the first cut will be engaged by the projections 25, as shown in Fig. '7; the strip C being lifted as it is advanced to clear the projection 25 and then being reseated on the die-plate 10.

The forward end of the strip C, consisting mostly of the first tooth, will then substantially clear the die-slot 16, while a neighboring portion of the strip C will extend over the die-slot 17. The press is then operated to cause the die 19 to again puncture the strip C and form a slot therein complementary to the previously formedslot,

as indicated by dotted lines in Fig. 7, and desig-.

-

jections

24 and 25 abutting against the opposite sides of the web portion F of the strip C extending between the slots formed by the first and second cuts, which web then extends over the die-slot 16 while a portion of the strip C will then extend over the die-slot 17.

thereof, as indicated in dotted lines in Fig. 8, and designated as third and fourth cuts, which are formed respectively by the dies 16 and 17and their associated punches l8 and 19. The third out forms a slot lengthwise of the .web' F which slot extends between the first and second cuts, and connects opposite ends'of said cuts, and thereby forms, between the first and third cuts and between the third andsecond cuts, teeth designated respectively as 2nd tooth, as shown in Fig. 9. a

The fourth out will then form a slotin the strip C corresponding'to the slots formed by the first and second cuts with a web G extending be tween the second and fourth cuts.

The strip C is then advanced to position the

projections

24 and 25 in the second and fourth cuts, whereupon theoperation just described is repeated and so on" until the strip C has been advanced step by step. throughout its length over the die plate 10 and until it has been divided g The press is then operated to cause the

punches

18 and 19 to penetrate the strip C and remove the portions tooth and 3rd into the rake-head strips D-andE, as shown'in Fig. 9. The strips D and E may be formed of any desired length and such as to' permit their being cut into shorter lengths according to the length of rake-headdesired. In this manner rake-heads of any required length may be produced by'a single punching mechanism.

In the formation of a rake it is desirable that theteeth thereof be tapered longitudinally so that the outer end portions thereof will be reduced transversely in relation to the inner end portions, and also that the teeth be of a thickness at theirouter end portions exceeding the width of the outer end portions. To attain this formation it is necessary that the rake-head strips be punched from a strip of metal having a thickness greater than the Width of the outer endiportions of the rake teeth, which, where it is desired to produce a punched rake of one-fourth of an inch thickness, is difiicult if not impossible of accomplishment by ordinary punch and die operations, since because the narrowness of the metal forming the rake teeth is such that, when the punch is forced through the webs between adjacent slots in the manner herein set forth, the side or marginal portions of the web are apt to spread so as to result in destruction of the taper at the outerend portions of the teeth and also bend the teeth laterally, thereby necessitating working of the teeth after punching thereof to bring themto the proper shape. This is overcome in the present invention by the provision of the

projections

24 and 25, which, by reason of being arranged to project alon'g'side'the opposite edges of the webs during punching thereof, act to retain the marginal portions of the web against lateral displacement.

' The

projections

24 and 25 are yieldably supported by the springs 2'7 so that they may be depressed in event of interposition of'any object between the projections and the stripper-plate may occur during the punching operations. Manifestly, while I have here shown the projectionsas carried on the die-plate, to project upwardly at opposite sides of the web, they .may be located on the stripper-plate to project downwardly therefrom, should occasion so require.

It has also been found that, because of the narrowness of the material along the margins of the web from which the rake teeth are formed, such marginal portions are apt to twist during penetration of the punch and also to bind. on the punch during withdrawal of the latter from the web, which results in miss-shaped rake teeth. This is overcome in part by the provision of the projecting rim 40 on the under side of the stripper-plate 30, which operates as follows: On depressing the punch member B, the stripper-plate 30, by reason of extending below the lower ends of the

punches

18 and 19, is caused to be disposed with the rim 40 seating on the marginal portions of the web, under pressure, before the punch 18 starts to penetrate the strip; thepressure of the stripper-plate on the web being increased as the punch member B advances relative thereto by the action of the resilient member 36 which is increasingly compressed as the punch moves into and penetrates the strip. In this manner the margins of the web are tightly clamped on the die-plate during the punching operation, and, by reason of the expansion of the member 36 to normal during retraction of the punch member B, the stripper-plate is maintained seated on the then formed teeth while the punch 18 is being withdrawn from therebetween, thus preventing twisting or bending of the formed rake teeth throughout the greater portion of the length thereof. The extremities or pointed tips of the formed rake teeth are formed without twisting by reason of the lateral extensions on the punches protruding beyondthe arched central portions of the punches so as to complete severance of the web at the ends of the formed teeth before severance of the web at the intermediate portions of the teeth is effected; the intermediate portions of the cutting edges of the punches by reason of being arched serving to hold the metal of the web against twisting while the projecting lateral extensions of the punches complete penetration of the web and thereby form the pointed tips of the rake teeth. This action is important in efiecting the third cut, when severance of the web F is made to form a pair of teeth as indicated in dotted lines in Fig. 8. it being found in practice that the rim 40 on the stripper plate 30 of itself is insufficient to hold the points of the teeth against twisting.

Another feature of the invention resides in forming the lateral extensions of the die-slots and punches with the semi-circle end walls a merging into the parallel side walls of the slots and punches on the curves b and whereby sharp corners on the punches and dies are obviated, thus rendering the dies more durable than would be the case if they were formed with angles. Furthermore, the lateral projections of the punches and die-slots are of a length greater than the width of the outer end portions of the rake teeth to be formed thereby, so that when the punch 18 is operated to cut the slot in the web F the ends of the punch 13 will protrude into the spaces formed by the laterally extending end portions of the punch '19, thus insuring removal of the material at the ends of thexformed rake tooth, and by reason of the relatively reversedicurves c at the juncture of the extensions 20 and 21 with the opposed outer sides of the die-slots and punches being arranged so that the are c on the extensions 26 and 22 will, when punching the web, intersect the arcs previously formed on the tooth ends by the-arcs c on the extensions 21 and 23, thus forming the tips of the rake teeth with sharp points.

While I have shown and described a specific embodiment of the invention, I do not limit myself to the exact details of construction and arrangement shown, but may employ such changes and modifications in the construction of the parts and in their arrangement as occasion may require coming within the spirit and scope of the appended claims.

I claim:

1. In a punching mechanism for forming a'pair of rake-head strips from a single strip of sheetmetal, a die-plate formed with at least a pair of prong forming die-slots, a punch member including punches conforming to said slots and cooperable therewith to form spaced slots in the strip of sheet-metal with a web therebetween, and means embodied in the punchingrmechanism forming abutinents for opposed edges of a formed web to prevent lateral spreading thereof during a subsequent punching operation eififiected on said web.

2. In a punching mechanism for forming a pair of rake-head strips from a single strip of sheetmetal, a die-plate formed with at least a pair of die-slots, a punch member including punches conforming to said slots andcooperable therewith toform spaced slots in the stripof sheetmetal with a web therebetween, means embodied in the punching mechanism forming abutments for opposed edges of a formed-web to prevent lateral spreading thereof'during a subsequent punching operation, and means in'said punching mechanism for holding the material of said web against twisting or bending during the subsequent punching operation.

3. In a punching mechanism for forming a pair of rake-head stripsfrom a single strip of sheet-metal, a die-plate formed with at least a pair of prong forming die-slots, a punch member including punches conforming to said slots and cooperabie therewith to form spaced slots in the strip of sheet-metal with a web therebetween, and means on said die-plate for retaining said web against lateral spreading thereof.

4. In a punching mechanism for forming 'apair of rake-head strips from a single strip of sheetmetal, a die-plate formed with at least a pair of die-slots, a punch member including punches conforming to said slots and cooperable therewith to form spaced slots in the strip of sheetmetal with a web therebetween, means on said die-plate for retaining said web against lateral spreading thereof, and means on said punch member cooperating with said die-plate for clamping said web during punching thereof.

5. In a punching mechanism for forming a pair of rake-head strips from a single strip of sheetmetal, a die-plate formed with at least a pair of die-slots, a punch member including punches conforming to said slots and 'cooperable therewith to form spaced slots in the strip of sheet: metal with a web therebetween, and upstanding spring pressed ins on saidv die-platearranged to project alongside a preformed web in said strip to hold the margins of said web against lateral movement during subsequent punching thereof. 6. In a rake punchingmechanism, including'a punch member and a die member, said die mem' forming to said die-slots for coacting therewithto' punch spaced slots in a strip of sheet-metal with a web therebetween, one of said die-slots and 7 its associated punch being arranged "to'punch a slot in said strip connecting opposed end portions of a previously punched pair of slots, and

upstanding projections on said die-plate. ar-' ranged in spaced relation to one of said :slots adapted to extend alongside of said web to prevent lateral spreading of the material-of said Web during punching thereof. p

7. In a rake punching mechanism, including a punch member and a die membensaiddie member embodying .a die plate formed with at -least a pair of spaced die-slots-disposed in angular relation to each other and having parallel side walls and oppositely-projecting lateral extensions at the ends thereof formed with arcuate end walls, said punch member including punches conforming to said die-slots for coacting therewith to punch spaced slots in a strip of sheetmetal with a web therebetween, one of said dieslots and its associated punch being arranged to punch a slot in said strip connecting opposed end portions of a previously punched pair of slots, and upstanding projections on said die-plate arranged in spaced relation to one of said slots adapted to extend on opposite sides of said web to prevent lateral spreading of the material of said web in either direction during punching thereof.

8. In a rake punching mechanism, including a punch member and a die member, said die member embodying a die-plate formed with at least a pair of spaced die-slots disposed in angular relation to each other and having parallel side walls and oppositely projecting lateral ex-' tensions at the ends thereof formed with arcuate end walls, said punch member including punches conforming to said die-slots for coacting therewith to pimcn spaced slots in a strip of sheetmetal with a web therebetween, one of said dieslots and its associated punch being arranged to punch a slot in said strip connecting opposed end portions of a previously punched pair of slots, upstanding projections on said die-plate arranged in spaced relation to one of said slots adapted to extend alongside of said web to prevent lateral spreading of the material of said web during punching thereof, a stripper-plate associated with said punches and carried by said punch member having slots through which said punches project, said stripper plate being mounted for conforming to saiddie-slots for coacting therewith to punch spaced slots in slots and its associated punch beingarranged to punchifaslot in said strip connecting opposed end p'ortions of a previously punched pair of slots, upstanding projections on said die-plate arranged inspaced relation to one of said slots,

adapte'dto extend alongside of said web to pre ventlateral spreading of the material of said web during punching thereof, a stripper-plate associated with'sa'id punches and carried by said punch member having slots through which said punches project, said stripper-plate being mount ed for movement relative to said punches, a projecting rim on the under side of said stripperplate arranged to bear on opposite marginal portions of said webduring. punching thereof, and meansfor maintaining "said rim seated on said web under pressure during withdrawal offthe punch therefrom.

10. Ina punching mechanism for forming a a strip of sheetf metal with .a web. therebetween, one ofsaid die pair of rake-head strips from a single strip of sheete-metal, a die memberincluding a idie plate formed witha "pair of die-slots, a'punch member including punches conforming to said slots and cooperable therewith to form slots in said strip, means on said die member for forming an abutment for one end of said strip to dispose the latter in position to be acted on by but one of said punches and its associated die-slot to form a single slot and one rake tooth, means engageable in said single slot on advancing said strip to position the latter on said die-plate where the previously operated punch will form a second slot in spaced relation to the first formed slot and produce a web between said slots, and means cooperating with said last named means engageable in said spaced slots on advancing said strip to position said web to be acted on by the other punch and its associated die-slot.

11. In a punching mechanism for forming a pair of rake-head strips from asingle strip of sheet-metal, a die member including a die-plate formed with a pair of die-slots, a punch member including punches conforming to said slots and cooperable therewith to form slots in said strip, means on said die member for forming an abutment for one end of said strip to dispose the latter in position to be acted on by but one of said punches and its associated die-slot to form a single slot and one rake tooth, means engageable in said single slot on advancing said strip to position the latter on saidIdie-plate where the previously operated punch will form a second slot in spaced relation to the first formed slot and produce a web between said slots, means cooperating with said last named means engageable in said spaced slots on advancing said strip web therebetween, said punches being arched longitudinally on the lower ends thereof so that their end portions will extend below their intermediate portions, and means engageablewith oppose dg 9? a f rmed we to re ent la e al pre d g t e f du i a Subsequent Pun-911mg operation forming an elongated'fslot therein oon n l the end ioa a the Pai 'QfPW'Yiously' formed slots on oppositesides of said web.

"13. In a punching mechanism'fofior'ming a pair of pronged rake head'strips f1forn a single strip of sheet metal, a die plate formed with'at least a pair oi spaced elongatedslots, each of said slots being formed ati ts ends with'lateral extensions of substantially circular outline, the

extensions on opposite ends of" each slot projecting laterally in opposite directionsj a punch member including punches conforming to'said slotsand cooperable therewith to form spaced elongated slots in a strip'oi sheet metal being punched withfa web therebtween, saidwfib, b fadapted tobe subsequently punchedby a pair of said punches to form a pair of. rongs rrom said web; the lateral extensions of said die-slots I punches being arranged so that on punching the" web they will protrude into space previously formed by the extensionsfat the ids of said K" V l Q. I I .r, i

In a punching mechanisxn for forming a pair of pronged rake head strips from a single strip of sheet metal, a die plate formed with at least a pair of spaced elongated slots, each of said slots being formed at its ends with lateral extensions of'substantially circular outline, the extensions on opposite ends of each slot projecting'laterally in opposite directions; a punch member including punches conforming to said.

slots and cooperable therewith to form spaced elongated slots in a strip of sheet metal being punched with a Web therebetween, said web beiiig e t to be se u l unched b a 52i? $.?i P nb o. o m a pair f p on iiom s i wen. he at ral ten of said die slots and punches being arranged. so that on punching the webl they will protrude into.