US2102941A - Method of forming bolt heads - Google Patents

Description

Dec. 21, 1937. H. CADWALLADER, JR 0 METHOD OF FORMING BOLT HEADS Filed June 2, 1937 INVENTOR Patented Dec. 21, I937 METHOD oF FORMING BOLT HEADS Harry Cadwallader Jr., Philadelphia, Pa. Application June z, ,1937, Serial No. 145,981

4 Claims.

The present invention relates to a method of making machine bolts and more particularly to a method of forming the heads thereof. In bolt heads as heretofore made by the drop forging method the partially completed blank or completed bolt head requires considerable machining such as grinding, trimming, and the like, to remove the fins and forging angles which have been a necessary adjunct of the forming operations. Furthermoregby prior methods there has been no certainty that thev head flanges will be of the same thickness, and more often than otherwise one is thin while the other is thick and .therefore an additional machining operation is necessary to complete thehead.

. Some of the objects of the present invention :are to provide an improved methodof making a vbolthead for a machine bolt; to provide a method wherein thematerialfor the head is upset and gathered into a preliminary shape without the formation of fins; to provide a step in'the method of making a bolt head wherein a second gathering operation is employed; to reduce the head to a second formed shape without producing excess metal at the forging angles or forming fins there-I on; to provide a bolt head forming method where-- in the flanges of the head are of uniform thick- .ness; to provide a method wherein the head is formed partially in a die and partially in a' .punch of die shape, the two members coactin'g in sucha way as to provide a head shape with,- outfins; and to provide other improvements aszwill hereinafter appear.

In the accompanying drawing Fig. 1 represents an elevation of .one part of a two part die with the associated punches in part section as arranged to carry out two successive steps of the method of the present invention; Fig. 2 represents a front elevation of the die block; Fig. 3 represents a front elevation of the punches; Fig. 4 represents a side elevation of the bolt stock after the first gathering operation; Fig. 5 represents a side elevation of the stock after the second gathering operation; Fig. 6 represents a diagrammatic plan of themechanism used in the final operation; Fig. 7 represents a diagrammatic elevation of the mechanism of Fig. 6; and Fig. 8 represents a perspective of the finished bolt.

Referring to the drawing one form of apparatus for carrying out the method of the present invention consists of a die block I0 which forms an anvil having preformed die shapes II and I2 by means of which two successive operations are performed. The invention is not limited to the particular single block construction here shown I as obviously two separate dies can be made to I serve the same purpose. The die shape II is in the form of a frusto-conical socket I 3 opening into a cylindrical hole 14 of such diameter as will snugly receive the round rod or blank [5 upon which the head of the bolt is to be formed. A punch l6 mounted for reciprocating movement towards and away from the front face of the block Ill is provided and located to register with the die shape I3. This punch I 6 is pro- .vided with a forming head having a frusto-conicalsocket I! in the face thereof, the arrangement being such that when the punch 56 is .in face contact with the block I0 bases of the two sockets I3 and I1 will register one with another to form a dieor mold having oppositely tapered end portions.

' The die shape l2 has agenerally rectangular socket opening into a cylindrical hole 2| which is to receive the rod l5 or part which becomes the shank of the finished bolt. Preferably the inner corners of the socket 20 are rounded to give a more finished effect. A punch 22 mounted for reciprocating movement towards and away from the front face of the block I0 is provided and located to register with the die shape 20. This punch 22 is provided with a forming head having a frusto-conical socket 23in the face thereof but which is of less depth than the socket I! and its volume is definitely calculated to receive approximately the required amount of metal necessary for working into the head shape by the final operation. a

Following the action of the punch 22, the partially formed bolt is transferred to a sliding head type of forging machine wherein the upset head 24 is placed in position to be acted upon by a top slide hammer 25, a bottom slide hammer 26, and two oppositely disposed side slide hammers 21 and 28. These hammers are reciprocated in .the well known manner of such machines, the

action being such that the top and bottom ham- In carrying out the steps of the present method a piece of round bar stock of proper length is placed in a heated condition within the die H with the end upon which the bolt head is to be formed projecting outwardly from the face of the block Ill. The punch I6 is now shot forward giving the end of the bar a sharp blow and since this end has entered the socket l1 it will be upset or gathered into a shape complemental to the two sockets l3 and IT. This is shown in Fig. 4 at 3B and 3!. Thus the preliminary step provides a partial head having a substantially smooth double tapered face minus any fins or projections. Upon the withdrawal of the punch it the partially shaped blank is'removed and placed in the die 12, whereupon the punch 22 is projected against the enlarged end and causes the tapered part 30 to flow into the socket 29 and form the same, while the part 3! which is in the socket 23 is enlarged in diameter but shortened in length giving the appearance of the head as shown in Fig. 5 wherein the part 32 consists of fiat sides spaced by the diameter of the shank and at its ends extending in both directions to merge into the frusto-conical part 33 resulting from the gathering of the metal in the socket 23. Thus again a more complete blank is formed but without fins or other irregularities such as are usually present in bolt manufacture. Following this operation the blank is again heated to forging temperature and placed in position between the sliding hammers of the header forging machine where the head is worked into shape by successive blows of the pairs of hammers and 26, and 2'! and28. These pairs as heretofore explained operate alternately, while the end hammer 36 operates simultaneously with each pair. This operation not only Works the head into final dimensions and shape, but also does the work without producing fins or forgingangles which ordinarily would have to be removed. The resulting completed bolt is shown in Fig. 8 and it will be evident that it has a smooth machine finished appearance and has been produced without the ordinary auxiliary step-s of machining and trimming. The threads 34 which complete the bolt are cut in the usual manner and form no part of the present invention.

Broadly considered the steps by which the shapes shown in Figs. 4 and 5 are formed may or may not include treatingbetween the two operations, because in some blank sizes the metal will hold its initial heat sufiiciently long to enable both steps to be carried out, but in other sizes it may be found necessary to reheat between these steps.

While but one form of apparatus has been shown in which this invention may be embodied, it is to be understood that the invention is not limited to any specific construction, but might be applied to various forms without departing from the spirit of the invention or the scope of the appended claims.

Having thus described my invention, I claim:

1. The method of forming a bolt head which consists in upsetting the end of a heated rod to form a head blank of double frustum shape, reheating the shaped blank and gathering the flowing metal to form a substantially rectangular base part having a frustum shaped head blank, reheating the blank, and hammering the sides and end of said head blank to form a bolt head of predetermined shape.

2. The method of forming a bolt head which consists in upsetting the end of a heated rod to form a head blank of double frustum shape, reheating the shaped blank and gathering the flowing metalto form a substantially rectangular base part having a frustum shaped head blank, reheating the blank, and alternately hammering the sides of the head blank in pairs while hammering the end of the head blank.

3. The method of forming a bolt head which consists in placing a heated rod blank in a fixed anvil die with an end projecting therefrom, striking the projecting end with a punch having a die socket to receive the projecting end, removing the partially formed blank and reheating it, placing the reheated blank in. another fixed anvil die with a portion of the formed head projecting therefrom, striking the projecting head portion with a punch having a die socket to gather the projecting portion into a predetermined shape, removing the partially formed blank and reheating it, and then hammering the sides and end to the finished size and shape.

4. The method of'forming a bolt head which consists in upsetting the end of a heated rod to form a head blank of substantially double frustum shape, then gathering the flowing metal underpressure toform a substantially rectangular partly curved base part having a frustum shaped head blank, reheating the blank, and hammering the sides and end of said head blank to form a bolt head of predetermined shape.

HARRY CADWALLADER, JR.

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