US2810140A - Gripper dies for nail machines - Google Patents

Description

1957 J. E. FOSTER EIAL GRIPPER DIES FOR' NAIL MACHINES Filed May 25, 1956 M m H m A m IF.J 2 Eu a p m L M J m Y B A i D :Iiliiiil v E l- \I/ I'll llll ll. \l l K 1 j l un A 3 av Q Nw HA3 5 a. H w fl Y/ JFI=| N IIIIIIMN J Ill-ll III I Ill'lllllll'lll'lll M 5 United States Patent ice A GRIPPER DIES FOR NAIL MACHINES James E. Foster and William J. Francis, Antioch, Califi,

assignors to United States Steel Corporation, a corporation of New Jersey Application May 25, 1956, Serial No. 587,424

2 Claims. (CI. 10-53) This invention relates to an improved spring arrangement for a gripper die in a nail machine.

Our spring arrangement is especially suited for gripper dies of duplex head nail machines of the so-called Glader type. Such machines embody a second set of dies in front of the gripper dies. In operation the usual reciprocable hammer acts against these second dies to upset a head on the nail end, while the second dies themselves act against the gripper dies to upset another head spaced from the end, all with a single hammer blow. Nevertheless, it is apparent our invention is not limited to any specific nail machine, but is applicable generally to nail machines which have a reciprocable, spring-restrained die.

An object of our invention is to provide an improved spring arrangement in which the springs are externally accessible and remote from the wire stock, thereby facilitating maintenance and preventing clogging with foreign material such as grease or nail whiskers.

A more specific object is to provide an improved spring arrangement which includes opposed compression and tension springs for restraining and cushioning a movable gripper die as it opens and closes, both springs being located externally of the dies remote from the Wire stock.

In accomplishing these and other objects of the invention, we have provided improved details of structure, a preferred form of which is shown in the accompanying drawing, in which:

Figure 1 is an elevational view of a die block and gripper dies of a nail machine equipped with our improved spring arrangement; and

Figure 2 is a horizontal section on line IIII of Figure 1.

The drawing shows a portion of a nail machine which includes a conventional die block 10, fixed and movable gripper dies 12 and 13 mounted in said block, a cam actuated lever 14 for operating the movable die, and a stop 15 for limiting its movement away from the fixed die. Wire stock W extends through a passage 16 in the die block, and is gripped between the two dies when the movable die is closed. A reciprocable hammer, not shown, upsets a nail head on the end of the wire, and in the example of a duplex head machine, a second set of dies, not shown, upsets another head spaced from the end. Next the lever 14 retracts the movable die and releases the wire, which thereupon feeds forward a nail length. The lever again closes the movable die, whereupon a set of cutters, not shown, sever the finished nail from the wire. These operations are repeated for each nail. Since machines of this type are well known, no more detailed description is deemed necessary. Nevertheless reference can be made to Little et al. Patent No. 2,381,171, for a full showing of a duplex head machine slightly modified from the Glader machine.

In accordance with our invention, the outer end of the movable die 13 contains a socket 17 which slidably receives a headed push pin 18. An externally accessible 2,810,140 Patented Oct.22, 1957 compression spring 19 encircles said pin and bears at its respective ends against the pin head and the end face of the. die; The outer end of the pin head contains a cup 20 which receives the tip of a pinch screw 21 threadedly engaged with the lever 14. Also in accordance with our invention, the movable die contains a transverse socket 22 which receives a hook 23, and the lever 14 carries an eyebolt 24. An externally accessible tension spring 25 connects the hook and eyebolt.

During operation of the machine, the movable die 13 must retract sufficiently so that the wire stock can feed freely between the dies, but not far enough to allow the wire to deflect out of position where the dies cannot position it properly on closing. As the lever 14 moves in a direction to retract the movable die, the tension spring 25 pulls the movable die to the limit permitted by the stop 15. Thereafter the lever continues to move away, with the tension spring afiording the necessary lost motion connection that absorbs further movement of the lever. The compression spring 19 holds the push pin 18 in engagement with the screw 21, the push pin sliding within its socket 17. As the lever 14 returns to close the die, the pin 18 slides back until it bears against the bottom of the socket and thereafter pushes the die to its closed position.

It is seen that both springs are remote from the point at which the dies engage the wire and from the cutters. Hence they are unlikely to become clogged with foreign material, but are readily accessible whenever maintenance is necessary. The arrangement has a further advantage over previous arrangements with which we are familiar in eliminating drilled holes in the die faces, and thus allowing use of die tips of hard but brittle material, such as tungsten carbide.

While we have shown and described only a single embodiment of the invention, it is apparent that modifications may arise. Therefore, we do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

We claim:

1. In a nail machine, which includes opposed fixed and movable dies adpated to grip wire stock, a lever for operating said movable die toward and from said fixed die, and a stop limiting movement of said movable die away from said fixed die, the combination therewith of a push pin slidably mounted on said movable die and projecting from the outer end face thereof remote from said fixed die, an enlarged head on the end of said push pin spaced from the end face of said movable die, means on said lever engaging said head, an externally accessible compression spring encircling said pin and bearing between said head and the end face of said movable die, and an externally accessible tension spring connecting said lever and said movable die for pulling said movable die away from said fixed die, said compression spring maintaining said head in engagement with said means after said stop prevents further movement of said movable die away from said fixed die, both of said springs being remote from the wire stock.

2. In a nail machine, which includes opposed fixed and movable dies adapted to grip wire stock, a lever for operating said movable die toward and from said fixed die, and a stop limiting movement of said movable die away from said fixed die, said movable die having a socket in its outer end remote from said fixed die, the combination therewith of a push pin slidably mounted in said socket and projecting from the outer end face of said movable die and adapted to bear at one end against the bottom of the socket, an enlarged head on the other end of said pin spaced from the outer end face of said movable die, projecting means on said lever engaging said head,

.an externally accessible compression spring encircling 3 l said pin and bearing between said head and the end face from said fixed die, both of said springs being remote of said movable die, and an externally accessible tension from the wire stock. spring connecting said lever and said movable die for pulling said movable die away from saidfixed die as said References Cited in the file of this Patent lever moves away, said compression spring maintaining 5 UNITED STATES PATENTS said head in engagement with said means after said stop prevents further movement of said movable die away 1251652 Farmer 1918 2,437,738 Hanggi Mar. 16, 1948

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