US3400438A

US3400438A - Combination punch press die

Info

Publication number: US3400438A
Application number: US603634A
Authority: US
Inventors: Robert L Montgomery
Original assignee: Northrop Grumman Corp
Current assignee: Northrop Grumman Corp
Priority date: 1966-12-21
Filing date: 1966-12-21
Publication date: 1968-09-10
Anticipated expiration: 1985-09-10
Also published as: BE749213Q

Description

R. L. MONTGOMERY COMBINATION PUNCH PRESS DIE 'Sept. 10, 1968 6 Sheets-Sheet l Flled Dec. 21, 1966 P 10, 1968 R. MONTGOMERY 3,400,438

COMBINATION PUNCH PRESS DIE Filed Dec. 2;. 1966 6 Sheets-Sheet 2 3g l/V/J/VTOL iaer/ Z. Maya/1199a P 10, 1968 R. L. MONTGOMERY 3,400,438

COMBINATION PUNCH PRESS DIE Filed Dec. 2;, 1966 6 Sheets-Sheet p 10, 1968 R. L MONTGOMERY 3,400,438

COMBINATION PUNCH PRESS DIE 1 6 Sheets-Sheet 5 Sept. 10, 1968 R. 1.. MONTGOMERY 3,400,438

COMBINATION PUNCH PRESS DIE Filed Dec. 21, 1966 6 Sheets-Sheet 6 United I States Patent 3,400,438 COMBINATION PUNCH PRESS DIE Robert L. Montgomery, Diamond Bar, Calif assignor to Northrop Corporation, Beverly Hills, Calif., a corporation of California Filed Dec. 21, 1966, Ser. No. 603,634 12 Claims. (Cl. 291.2)

ABSTRACT OF THE DISCLOSURE The method of making a flechette comprises feeding the end of a long length of wire to an operating station, forming a pinched-off point in the wire at a distance from the leading end thereof corresponding to the desired length of the article, cutting off the wire beyond the formed point to produce a short length of scrap, then forming a fin-like vane or other head on the leading end, and then feeding in the next desired length of wire for repeated operation. Briefly the apparatus comprises a matching punch and die assembly adapted to be installed in a punch press, the assembly comprising pointing dies, a cut-off blade, and vane-forming dies, all arranged to be cycled once in a predetermined sequence during a single stroke of the punch press. To allow longitudinal movement of the wire article during the vane forming operation, a small scrap piece is removed at an intermediate wire portion when the point is formed.

The present invention relates to machine tools, and more particularly, to a means and method of manufactoring metal darts or the like, commonly called fletchettes.

Such metal darts have been proposed previously for use as missiles in various armament applications. However, due to the expensive machinery heretofore required for their manufacture, their use has not become widespread. All conventional methods utilize either nail-making machines requiring extensive alterations or complicated four-slide forming machines, and the tremendous quantities involved have made them too expensive to be practical.

It is an object of the present invention to provide a way of making flechettes, nails, or similar articles, which is very substantially cheaper and more productive than prior existing machinery and methods.

A further object of this invention is to provide a tool for making such articles in a punch press.

Since the flechette has a point and a shaped head or vane, it is an ancillary object to provide all the necessary sequential operations for making a complete article in a single stroke at a single station in the tool.

This invention will be more fully comprehended from the detailed description to follow, and from the accompanying illustrative drawings.

In the drawings:

FIGURE 1 is a plan view of the punch portion of the combination die assembly.

FIGURE 2 is a plan view of the die portion of the assembly.

FIGURE 3 is a front view, partly in cut-away and sectional form, of the assembly, viewed as indicated by broken line 33 in FIGURE 2, showing the position of the pinch-pointing dies and associated parts at the end of the down stroke.

FIGURE 4 is a portion of a cross section view of the entire assembly, taken as indicated by broken line 44 in FIGURE 2, showing a pressure pad for holding wire material in place.

FIGURE 5 is a further cross section, taken as indicated by broken line 5-5 in FIGURE 2, showing the coining or vane-forming dies and associated parts.

FIGURE 6 is a longitudinal section, taken as indicated by broken line 6-6 in FIGURE 5, showing a further view of the parts of the assembly along the line of wire material insertion.

FIGURE 7 is a schematic diagram illustrating the arrangement of the major working parts of the present device as viewed from above.

FIGURE 8 is an enlarged perspective view of a fiechette produced by the present invention.

Referring first to FIGURES l, 2, and 6 for a detailed description of a specific embodiment of the invention, an upper tool portion termed a punch 1 and a lower tool portion termed a die 2 are linearly movable with respect to each other, and are aligned by means of two guide posts 4 which are fixed to the die 2 and vertically slidable within two ball-bearing type bushings 5 mounted in guide holes 6 in the punch 1. ball bushings 5 are not used, the guide posts 4 can be merely slidable in the guide holes 6. In all figures except FIG- URE 7, the punch 1 is shown in its closed position, i.e., at the extreme downward position. Reference may be had to the simplified diagram in FIGURE 7 for the overall relative position of the major working parts.

As shown in FIGURES 6 and 3, wire material 7 entering the tool passes through a feed opening in an entrance block 9 fastened to the die "2 and rests in a groove in a support anvil 10 (FIGURE 4) also fixed to the die 2. A pressure pad 11 on the die 2 is lightly spring-loaded downwardly toward the anvil 10, and contacts the wire material 7 to normally hold it lightly in place. A springloaded plunger 12 is mounted in the punch 1 and puts substantially greater force on pressure pad 11 when the punch 1 is lowered relative to the die 2.

As shown in FIGURE 3, a pair of pinch-pointing dies 14 and 14a are mounted by means of set screws 15 in opposed fashion in respective sliding holders 16 and 16a in the die 2. Dies 14 and 14a are located just in front of the pressure pad 11, with the wire entrance side of the tool being termed the front. Each die holder 16 and 16a carries a compression spring 17 (FIGURE 2) which bears against respectively opposite sides of the central entrance block 9, to thus normally spread the pinch-pointing dies 14 and 14a apart. A vertical channel 19 in the outer end of each holder 16 and 16a carries a cross pin 20 adapted to be contacted by a cam projection 21 on a pivoted cam 22. This cam 22 (one for each die holder) is pivotally mounted on an axis pin 24 secured to the punch 1. When the cam 22 is in a horizontal position as illustrated, its upper inner end surface 25 butts solidly against a structural abutment 26 of the punch 1. Cams 22 can each rotate downwardly at their inner ends, however, against the positioning action of respective spring-loaded cam rods 27. The operation and purpose of this cam construction will be described later.

Referring now especially to FIGURES l and 6, vertically extending cutter 29 is solidly attached to punch 1, and its lower end carrying a cutting blade 30 fits between the entrance block 9 and the pinch-pointing dies 14 and 14a. With punch 1 in its lowered position, wire 7 is sheared off at point A as shown in FIGURE 7. Blade 30 is assisted in its cutting operation by a close-fitting bushing 31 in entrance block 9.

In FIGURE 5, four coining dies 32, 32a, 32b, and 32c are radially positioned facing the leading end of wire material 7 at -degree angles. The coining dies 32 are slidably mounted in a die block 34 fixed in die portion 2 behind the pressure pad 11, and each coining die 32 is spring-loaded to a retracted position. The central ends of coining dies 32 are chisel shaped to form vanes 35 on 3 the fiechette wire when mutually closed. A special beveled edge 36 is also provided on each coining die point, to form a sloping transition between the fiechette body and vanes.

The two upper coining dies 32 and 32a are acted upon directly by two 45-degree sloping strikers 37 mounted on the punch 1. The two lower dies 32b and 320 are acted upon by four intermediate 45-degree sliding blocks 39 mounted in the die 2, and by two vertically adjustable contact bolts 40 mounted in the punch 1. It is thus seen that when bolts 40 are properly adjusted, the coining dies 32 are solidly bottomed against the formed vanes 35 at the extreme bottom of the punch stroke.

Other parts and features of the die set are considered conventional in the art. Lubrication tubes 41 and passages 42 are preferably provided to lubricate the various sliding surfaces.

In use, the present punch and die combination is placed in a punch press, with an upper shank 44 of the punch 1 being clamped in the reciprocating ram of the press, and the die 2 being secured to the press bed by a suitable bolted facility clamp, for example. A four-posted type of press is preferred because of its rigidity.

The operation of the present invention will now be described. In connection with this, a conventional type of intermittent wire feed mechanism shown generally at 45 in FIGURE 6 is employed. Each time the punch portion 1 rises to its upper position, a feed valve actuator 46 is contacted, to initiate a feed cycle and thus feed a predetermined amount of wire material 7 from coiled stock into the machine.

As the punch 1 lowers, plunger 12 contacts pressure pad 11 to stabilize the wire. Next, the cam projections 21 strike the cross pins and force the pinch-pointing dies 14 closed to form a nail-type point 43 in the wire, this point pointing away from the newly inserted wire end. The pointing dies are preferably held closed during a punch travel sufficient for cutter blade to now pass through the wire. This closed pointing die position is held by virtue of a short flat end 47 on the cam projections 21, the vertical dimensions of fiat end 47 being substantially equal to the wire diameter.

With slightly further travel, cam projections 21 pass below the cross pins 20, and pointing dies 14 spring open. The preceding operation has thus trimmed off and ejected a small piece of scrap 49 (FIGURE 7), which falls down and away through the die 2.

Final punch movement on the down stroke presses the coining dies 32 closed to form the stabilizing vanes on the fiechette 50. During vane forming, the beveled edges 36 on the coining dies force the wire backward a substantial amount under the pressure pad 11, and it will be noted that such movement is allowed because of the scrap 49 being previously removed and because the pointing dies 14 were allowed to open on the latter part of the down stroke. If no provision were to be made for this necessary wire movement, the wire would buckle and spoil the art, as well as causing probable malfunction of the tool.

On the up stroke, the coining dies 32 are allowed to retract, and the cams 22 bypass the pointing dies 14 by pivoting outwardly against their spring-loaded rods 27 when the cross pins 20 strike the top of the projections 21. After this ratchet-like action, the earns 22 flip back into operating position above the cross pins 20, ready for the next cycle. The cutter 29 also comes up, and the plunger 12 is raised from the pressure pad 11. Now the wire feed mechanism is actuated as previously described, forcing a new length of wire 7 into place. The new wire length strikes the point of the prior completed fiechette 50 and forces it straight through the back of the die 2, where it drops into a delivery chute (not shown). A finished ficchette 50 is shown alone in FIGURE 8.

It is thus seen that such articles are economically and rapidly produced. In one embodiment for making oneinch fiechettes, the press stroke is approximately one inch and the invention operates successfully at a rate of about five strokes per second.

Further, the present invention can be employed to produce articles having other shapes of head and point than those disclosed herein. It would be suitable, for example. to replace the coining dies with a fiat head forming die and proper actuator means therefor, to manufacture nails. The same single-stroke punch press operation would be obtained.

While in order to comply with the statute, the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the method and means herein disclosed comprise a preferred form of putting the invention into effect, and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.

What is claimed is:

1. The method of forming flechette or the like at a single work station, comprising:

(a) feeding a desired length of stock from a bulk supply to a work station;

(b) forming a pinched-off point in said stock at a desired distance from the leading end thereof, said point pointing away from the stock leading end;

(c) cutting off said stock a short distance beyond said point, to thus produce a separate scrap piece from said stock;

(d) forming at least one dart-like vane on the stock leading end; and

(e) feeding a next desired length of stock to said work station, thereby ejecting the previously formed flechette article from said station.

2. Method in accordance with claim 1 including holding said stock by a slip-type clamping action during forming of said vane, whereby longitudinal motion of said stock is allowed.

3. The method of forming a pointed and headed article comprising:

(a) feeding a desired length of wire-like material from a bulk supply to a forming station;

(b) forming a pinched-off point in said material at a desired distance from the leading end thereof;

(0) cutting off said material a small distance beyond said point from the leading end; and

(d) forming a head on the leading end.

4. The method of forming a pointed and headed article, comprising:

(a) feeding a length of material to a forming station;

(b) forming a pinch-off point in said material at a distance from the leading end thereof; and then (c) forming a head on said leading end.

5. A tool for forming flechettes or the like, comprising in combination:

(a) a die portion;

(b) a punch portion;

(0) alignment means connected to said portions for restraining relative movement therebetween to a prescribed linear path between closed and open positions;

((1) a biased pressure pad on said die portion for holding a wire at a forming station;

(e) a pair of horizontally opposed pinch-pointing die assemblies slidably mounted in said die portion in front of said pressure pad, a cross pin fixed in the outer end of each of said assemblies, elastic means urging said assemblies to a retracted position, said pointing die assemblies having wire pointing means at their inner ends to form a point in said wire and pinch off said wire at the formed point when said assemblies are moved to a closed position;

(f) a pair of cams pivotally mounted on said punch portion and each having an integral slanted driving projection positioned to contact said cross pins,

(1) stop means on said punch portion positioned to abut said cams and hold said cams from pivoting when said punch portion is on a down stroke toward its closed position, so that said pointing die assemblies are driven closed together by said cams, said cams positioned to travel beyond said cross pins and thereby release said pointing die assemblies before said punch portion reaches its closed position,

(2) elastic means normally urging said cams to a rest position against said stop means, said cams being pivotally movable against said elastic means when said projections contact and pass by said cross pins on the up stroke of said punch portion, so that said pointing die assemblies remain retracted on said up stroke;

(g) cutter means on said punch portion having a blade positioned to cut off said wire in front of said pointing dies after said pointing dies have been closed;

(h) four radial coining dies mounted in said die portion in back of said pressure pad, said coining dies being slidable between open and closed positions and normally elastically held in said open positions, said coining dies each having substantially chisel-like inner points to form four vanes in said wire when said coining dies are in said closed position; and

(i) actuator block means in said punch portion and in said die portion having angular faces arranged to contact the outer ends of said coining dies in sliding relation to push said coining dies to said closed position when said punch portion is completely in its 7 closed, or down, position.

6. Apparatus in accordance with claim 5 wherein said radial coining dies are located along 45-degree slanting lines, and wherein said actuator block means comprises a pair of upper blocks secured to said punch portion and having respective 45-degree contact faces located to slidingly engage the upper two of said coining dies, a pair of horizontal blocks horizontally slidable in said die portion and having 45-degree inner faces located to slidingly engage the lower two of said coining dies, said horizontal blocks each having 45-degree outer faces, a pair of vertical blocks vertically slidable in said die portion and having 45-degree lower faces engaging said 45-degree outer faces of said horizontal blocks, and a pair of adjustable bolt members fastened in a vertical position in said punch portion, said bolt members having lower head elements positioned to respectively contact the upper ends of said vertical blocks, said bolt members being adjusted so that said lower two coining dies operate in synchronism with said upper two coining dies.

7. A tool for forming articles having a stem-like body, a point and a head, comprising:

(a) a die portion;

(b) a punch portion relatively movable with respect to said die portion;

(c) means defining a work station in said die portion for holding said body of said article;

((1) pointing die means in said die portion in front of said work station for forming said point on said body;

(e) cam actuating means on said punch portion for operating said pointing die means through a complete pointing cycle during a down stroke of said punch portion, said cam means :being pivoted to bypass said pointing die means during an up stroke of said punch portion;

(f) cutting means on said punch portion positioned to cut off said body in front of said pointing die means after said point is formed;

(g) heading means on said die portion positioned to form said head on said body in back of said work station; and

(h) heading actuator means operated by said punch portion arranged to actuate said heading means at the bottom of said down stroke;

(i) whereby said article is completely formed at said work station during a single stroke of said tool.

8. Apparatus in accordance with claim 7 wherein said punch portion has an upper shank adapted to be connected to the movable drive member of a punch press, and wherein said die portion is adapted to be fastened to the punch press bed.

9. Apparatus in accordance with claim 7 including an incremental material feed control member mounted to be cyclically contacted and operated by said punch portion near the end of the up stroke thereof.

10. Apparatus in accordance with claim 7 wherein said pointing die means and said heading means are both spring-loaded to their respective open, non-operative, positions.

11. Apparatus in accordance with claim 7 wherein said tool includes an entrance in front of said cutting means for receiving bulk wire-type material to be formed, said cutting means positioned to cut off a small amount of said wire material beyond said point from the leading end of said material, and wherein said heading means comprises a plurality of radially positioned vane-forming dies located to form at least one arrow-like vane in the leading end of said wire material.

12. Apparatus in accordance with claim 11 wherein said vane-forming dies each have a substantially chiselshaped forming end and a receding beveled edge on the side of said chisel end toward said body of said article, said work station means having a limited pressure means in contact with said body, whereby said article is allowed to slip backward a small amount as said vane is being formed.

References Cited UNITED STATES PATENTS 2,356,966 9/1944 Bardell 29--1.2

RICHARD H. EANES, JR., Primary Examiner.