US2227810A - Die structure - Google Patents

Description

Jam 7, WM. H. MRTCHELL DIE STRUCTURE Filed Dec. 5, 1938 flsATTORN Patented Jan. 7, 1941 UNITED STATES PATENT OFFICE on: smoc'romz Delaware Application December 5, 1938, Serial No. 243,959

3 Claims. 10-24) This invention relates to improvements in dies for use in heading machines of the type adapted to make headed screws, rivets, nails and the like, a particular object being the provision of a die which is simple in construction and requires less material than dies of the same class made y the old methods, the improved die having a considerably longer life than the old dies and making a. uniform product for a greater number of i0 operations.

Another important object is the provision of improved seating means for mounting a die in a heading machine or other utilization means to eliminate the danger of splitting and other in- 18 juries where the die is subjected to great pressure.

Another object is the provision of a die of novel construction comprising a die core and a holder therefor and characterized by the fact that the 20 core may be of reduced size and bulk compared to the holder, the reduced size making it possible to temper or harden the core more uniformly throughout the entire mass thereof than was possible in the older type of die.

26 Viewed from another aspect, it is an important object of the invention to provide a die consisting of a bushing adapted to fit into a die holder or seat, said bushing being split in an axial direction along one side thereof and having fill secured in its bore a die plug of substantially less bulk than the bushing and highly tempered, the bushing making it possible to employ a die plug of relatively small mass and thus making it possible to thoroughly temper the plug.

355 Still another important object is the provision of a bushing having outer peripheral portions tapered for reception in a tapered seat, pressure being applied at one end of the plug corresponding to the larger end of the bushing so ll that the latter is wedged into the seat proportionately to the pressure applied, so that the die plug will likewise be proportionately gripped by the bushing.

Other objects, advantages, economies, and

45 novel aspects of the invention reside in certain details of construction and operation of the parts of the preferred embodiment, all of which will be made to appear as the following description proceeds in view of the annexed drawing, in

50 which:

Fig. 1 is a perspective view of a die bed in a heading machine with the novel die seated in operative position;

Fig. 2 is a cross section along line 2.--2 of 55 Fig. 1, scale being slightly nlarged;

Fig. 3 is a cross section through thedie along line 3-3 of Fig. 2 and to slightly enlarged scale;

Fig. 4 is a perspective view of the split bush+ ing; while Fig. 5 is a perspective view of one form of die 5 plug. v

Extruding and heading machines commonly employ a die holder or'bed in which a die plug is removably mounted to have pressure applied against the exposed end thereof to form or deform stock which is fed into position before the die or into the die, in cooperation with pressure means, usually some form of plunger. Dies made in accordance with the methods heretofore known have been unsatisfactory because their life is limited due principally to the fact that they cannot be tempered by practical industrial methods to a degree of hardness which will withstand the tremendous pressure applied thereto for any great length of time. In order to give these dies 9, maximum life, the bulk or mass of a given die could not be reduced beyond a given point, or, stated in other terms, the size of a die for a given operation could not be reduced below a given dimension if the die were to stand up for an appreciable number of operations. In accordance with the former methods, these dies were first tooled and then tempered or hardened and because of their bulk, the tempering of the metal was not uniform throughout its mass, the dies being harder around their marginal portions and softer in directions inwardly from the marginal portions into the body thereof. As a consequence, such dies tend to split under repeated applications of the relatively enormous pressures necessary to extrude or deform metal stock engaged therewith.

The present invention overcomes the foregoing difiiculties and provides a die which elimi- 4o hates splitting, which is of simple construction and which reduces the material required for the entire die assembly, and thus lowers costs, and which moreover makes it possible to provide a more highly and uniformly tempered die which 5 will assure a uniform product over a longer period and for a greater number of operations of the forming machinery.

In one of its preferred forms, the improved die includes a chuck or holder in the form of a metal sleeve l0 (Fig. 4) which is tapered from one end Illa inwardly toward its opposite end it?) on the outer periphery thereof. The chuck or holder is split as at H in an axial direction from the end llla toward the end Nb so that the bore l2 may be said to be somewhat expanslble.

The die proper includes an insert or plug l5 (Fig. 5) which in this instance is provided with 5 a bore l6 throughout its length (Figs. 2 and 3 also), the axial ends of the plug in this instance being countersunk as at I! to provide a heading formation for the manufacture of a fiat head rivet or screw or analogous device from rod- 10 like stock l8 which is fed into the outer end of the plug (as illustrated in dotted lines in Fig. 1). The die insert or plug is dimensioned to fit snugly into the bore I2 of the chuck or holder It) as shown in Figs. 2 and 3, the opposite ends 15 of the plug being flush with the extremities Illa and "lb of the chuck. With the parts l and I thus assembled, the forming die is complete and ready for insertion in the die bed or seat.

The invention further contemplates an im- 20 proved seating means for such dies, such a means comprising: as viewed particularly in Fig. 2, a seating block 20 which may be variously shaped to fit into the die bed or holder in various heading or extruding machines, opposite side portions 25 2t and 22 of the block being beveled or sloped to fit into a. bed 23 in the forming machine, this bed including a keying block 24 secured in place by a locking nut 25 against the side 2i of the seating block to hold the latter immovably in 80 the bed.

The seating block 20 is provided with a bore 28 tapered to receive the chuck or holder it of the die so that the outer end portion Illa thereof will lie fiush with the outer face of the block 29.

35 In the operation of the forming machine chosen for illustrative purposes herein, there is a. stock feeding channel 32 leading from the bed 23 into register with a feeding sleeve 3! also removably secured in the seating block 20, 40 rodlike stock such as the blank l8 being fed automatically by mechanism not illustrated herein, so that a predetermined length of stock issued from the outer end of the feeding sleeve 3i and is automatically cut off by a shear 32 moving 45 across the opening of the feeding sleeve, the

shear being provided with holding means 33 wherein the sheared blank is secured by a springurged finger 34 (Fig. 1) while the shear cone tinues movement toward the die to align the 50 blank with the bore I6 of the die insert. When thus aligned, the blank I8 is moved into the bore l6 by timed movement of a plunger 35.

The blank is backed in the die by a combina tion backing and kick-out rod 36 (Fig. 2) which 55 is urged by a plunger 31 into the bore I6 of the die against the innermost end of the blank in properly timed relation to the movement of the heading plunger 35 so that the outermost end portion of the blank is forced into the tapered or 0 enlarged end portion l1 and constitutes a fiat head on a rivet or screw, the knife and holding means meanwhile having been withdrawn from the path of the plunger 35 and the latter withdrawing afterformation of the article, and the 65 knock-out plunger 31 thereafter moving forward (to the right) to eject the headed screw or rivet from the die, whereupon the machine is ready forthe next cycle of operation.

Due to the taper of the bushing or die holder and the corresponding taper of the seating block 20, the increase in gripping pressure of the bushing on the die insert l5 may be said to be substantially proportionate to the pressure applied 5 by the plunger 35 and is at all times adequate to secure the die in exactly alignedposition, the die holder in nevertheless being readily removed from its seat 20 when it is to be replaced by a different die. The gripping pressures exerted upon the insert by the bushing or holder are substantially uniformly distributed and this, coupled with the fact that the improved die construction makes possible a complete and effective tempering of the insert, results in a die of exceptional durability and one which will hold its tolerances for a considerably greater number of operations thanthe old type of die.

The objects and advantages of the invention may be realized in modified forms of construction, and the invention is therefore not to be restricted to any of the precise details recited herein in describing an illustrative embodiment thereof except as may be provided in the appended claims.

Having thus described my invention, what I claim as new and desired to protect by Letters Patent is:

1. A heading die including a holder in the form of a tubular bushing which is split along one side throughout its length, and a tempered die insert of cylindrical form and minimized cross sectional thickness sumcient to facilitate uniform tempering fitted into the tubular portion of said holder, the latter being adapted normally to grip said insert and hold the same securely in place, the slotted formation of the holder providing yieldability thereof in a circumferential sense for removal of the insert.

2. A heading die including a holder of sub- 40 stantially tubular form split along one side throughout its length and having a die insert of minimized cross section to facilitate tempering, said insert being highly tempered and fitted intothe bore thereof, said holder having outer peripheral portions tapered from one end toward the other to fit into a correspondingly tapered die seat, pressure being applied to said insert at the larger end of said holder so that the latter will be forced into said seat, the split formation of 60 the holder permitting the same to be tightly contracted about said insert to hold the latter against substantial movement during application of pressure thereto.

3. .A tempered heading die for use in a. conical- 1y tapered seat, said die comprising a holding sleeve having a cylindrical bore and conically tapered outer wall portions adapted to fit into said seat, said sleeve being slit longitudinally to permit expansion and contraction across said bore, and a tempered cylindrical die insert having an optimum minimized cross-sectional thickness rendering the same permeable to tempering and hardening agencies throughout a major part of its bulk, said insert fitting into said bore in the holder and being reinforced and held by the latter when operatively disposed in said seat.

HARVEY MITCHELL.

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