US1935821A - Wire drawing die - Google Patents

Description

Nov. 21, 1933. $|MONS 1,935,821

' Q WIRE DRAWING DIE Filed Oct. 2, 1929 INVENTOR Marrals' Jimons ATTORNEYS Patented Nov. 21, 1933 I WIRE DRAwmG DIE Morris Simona, New York, N. Y.

Application October 2, 1929. Serial No. 396,657

1 Claim.

This invention relates to dies involving the use of an extremely hard composition including tungsten carbide. A suitable material as at present manufactured comprises approximately 85% tungsten carbide, 10% cobalt, and 5% carbon.

In making dies from this material the ingredients, in finely subdivided state, are thoroughly mixed, pressed into a mold of the desired shape, and subjected to the action of an electric furnace. The resulting product is extremely hard and very eflicient for cutting purposes, but difliculties are involved in the use of it for wire drawing because of the lack of sufficient tensile strength.

In carrying out my invention I provide a nib of such material, which is preferably of annular form, but the passage through the center is ordi-' narily not finished to the exact diameter required for the size of wire to be drawn. The wall of the passage may be left in the rough.

By means of my invention I am able to support such a nib, resist outward disruptive forces caused by the drawing of the wire, and may permit the die to be used for successively larger wires until the nib is almost entirely used up.

In the accompanying drawing I have illustrated a preferred embodiment of my invention. In this drawing:

Fig. 1 is a central longitudinal section through the die in flnal form, and v Fig. 2 is a similar section showing the parts prior to the final assembling operation.

In making my improved die, an annular nib 10 is set within a chamber or recess of a plug 11, and against a shoulder 12 adjacent to one end of the plug. Beneath the shoulder the plug has a passage 13 of considerably larger diameter than that required for the wire to be drawn.

The plug 11 is externally tapered, the included angle being preferably about 2 to 4. The shoulder 12 is near the smaller end of the plug. A holder 14 is provided which is of a thickness substantially equal to the thickness of the plug, and it is provided with a passage therethrough tapered to substantially the same angle as the exterior of the plug. The plug 11 and the holder 14 are preferably of steel. The plug is of slightly larger size than the passage in the holder, so that the plug will go into the hole only to approximately the extent indicated in Fig. 2.

The plug is made of a piece of seamless tubing approximately'50% longer than the height of the hard nib. This piece of tubing is heated to a red heat while in a press. Then the nib is placed in the tubing which has a slightly larger bore than the outside diameter of the nib, and pressure is applied by a die so that the extra length of the metal tubing is forged over the top of the nib, thus forming the flange which, in the finished construction, forms the shoulder 12. At the same time the pressure causes the metal to fill very tightly in around the outer surface of the nib. As the plug cools, it shrinks around the nib so as to grip the latter very tightly. After it is cooled the plug is turned in a lathe so as to have the taper and form shown in the drawing, the smaller end of the plug being the one having the shoulder 12. The plug is then placed in the aperture in the steel holder, and high pressure is applied to force the plug axially from the position shown in Fig. 2 to the position shown in Fig. 1.

During this movement of the plug the plug is contracted radially and caused to very tightly and firmly grip the exterior of the nib, and to provide a firm, close-fitting reinforcement which resists any outward radial strains on the nib. The shoulder 12 resists any endwise movement of the nib during the use of the die, as it will be understood that in operation the wire passes through the die in a direction tending to pull the nib against the shoulder 12 and to pull the plug still further into the holder.

After the parts have been assembled in the manner above described, the inner surface of the nib may be finished to the desired diameter and smoothness, in accordance with the size and material of the wire to be drawn. A nib of this character and made up essentially of tungsten carbide, is particularly useful in the drawing wire of steel and other material. The device may be used for drawing wire tubing or rods, or for any other drawing process.

It will of course be evident that my invention is not limited to the use of the specific composition above referred to, as this composition may be varied. Embodiments thereof are sold under various trade-names.

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

A wire drawing die including a nib comprising essentially tungsten carbide, said nib having a cylindrical peripheral surface and a wire drawing passage therethrough, a metal plug having a cylindrical bore to hold the nib and open at one end, and having at the opposite end a shoulder forming a seat for one end of said nib, the exterior of said plug being frusto-conical and of smaller diameter at the end having said shoulder, and a holder having a frusto-conical passage therethrough within which said plug is mounted, the walls of said latter passage firmly gripping the outside of said plug to hold said plug under radialcompression and to resist radial forces exerted within the nib during the operation of the die.

MORRIS SIMONS.

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