US338276A - Die for swaging screws - Google Patents

Description

' (No Model.)

B. A. KENNEDY.

DIE FOR SWAGING SCREWS.

Patented Mar. 23, 1886 UNITE STATES arena? UFFICE.

BURR A. KENN DY, OF LAKE view, ILLINOIS.

DIE FDR SVVAGENG SCREWS.

SPECIFICATION forming part of Letters Patent No. 338,276, dated March 23, 1886.

Application filed January 5, 1885.

T0 aZZ whom it may concern:

Be it known that I, BURR A. KENNEDY, of the town of Lake View, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Dies for Forging Screws, of which the following is a full description, reference being had to the accompanying drawings.

The object of this invention is to make the forging of screw-threads practical as distinguished from those made by cutting out the grooves, as with dies.

As shown, my method of forging is better adapted to the making of what is known as the half-V thread, but any other can be formed by proper adaptation of the dies.

In the drawings, Figurel shows the blank from which the form of screw shown in Fig. 2 is forged. Fig. 3 is aperspective view of the operating parts of an ordinary trip-hammer to which my dies are attached. Fig. 4 is a face View of the upper die, and Fig. 5 is aface View of the lower die. Fig. 6 is an end view of the lower die. Fig. 7 showsa simple form of screw used for piano-stools, for the production of which the method and dies here shown are well adapted.

A is the helve of the trip-hammer.

A is the upper die-block.

A is the upper die.

B is the anvil-block.

B is the lower die-block, and B the lower die. Each die is provided with a form or recess for roughly shaping the thread, and another form or recess for finishing the thread.

0 and G are the two shaping-forms, which are of corresponding or complementary shape, and D D the finishingforms, which are also complementary. The shaping-forms O G are of semicircular form in cross'section, so that a circular opening is presented between them when they are closed together. Each of these forms is of diminishing size from the end at which the blank is received to the opposite end at which the blank is delivered. The walls of these shaping-forms G O are provided with screw-threads approximating in form and size, the threads being of the required scope, and their diameter at the smaller end being very slightly greater than required on the finished screw. The heated bar or blank is Serial No. 152,094. (No model.)

passed endwise between the dies while the hammer is in motion, being entered between the larger ends of the forms 6 G and turned gradually forward. In this manner a screwthread is gradually beaten into the blank, the form and depth of the thread being gradually developed as the blank proceeds through the forms from the larger toward the smaller end. On emerging from the dies the screw presents the appearance presented in Fig. 2, with a well formed but as yet unfinished thread thereon.

D D are the finishingforms, having internal threads of the size and depth corresponding precisely with those of the screw to be produced. These finishing -forms are commonly ofuniform diameter from end to end, with several threads or convolutions of a thread therein, as shown in the drawings, so that the screw may be kept straight while being finished thereby. The rough screw, on leaving the forms G G, is subjected to the action of the forms D D, which serve to reduce it to the exact size and to give the threads that accuracy and smoothness of finish which is necessary to its proper action when in use. It is preferred to have the roughened forms G O and the finishing forms D D distinct from each other, as shown in the drawings; but if preferred the finishing forms may be arranged in line with and as coutinuations of the roughening-form, in which case thescrew will be finished in a single passage between the dies.

i D and Dare the finishing-dies,being matrices formed with threads of size and depth exactly equal to the finished screw to be. This finishing-die is made of several threads in length, so that as the screw passes through it is kept straight.

For the form of screw shown in Fig. 2 the blank shown in Fig. 1 is prepared. I prefer to make the stems e and c of this blank of a size slightlylless than the diameter of the screw at the bottom of the threads. These stems may then be thrust between the dies, even while the hammer is in motion, and they form a guide to direct the thread, already roughly made, into the finishing-dies as it is pressed forward and turned to screw it in. Were not some such provision made it would be very difficult, if not impossible, to place the screw ceiving toward the delivery side,wl1ereby the in the finishing-die without stopping the ham- In order that a screw like that shown in Fig. 7 may be made to enter the die while the hammer is in operation, the dies have an unthreaded space, f and f, of diameter equal to that of the shank of the screw. Into this the end of the screw is laid, and as it is pressed forward and. slowly rotated it is screwed into the die and smoothed. It is preferable to make the screw a little larger than the finishing-dies, so that the latter will have stock to work on, as this produces smoother work.

In coach-screws and other coarse screws the finishing-dies may not be required, the forming-dies being sufficient.

It is not necessary to make the finishingdies (when they are used) in the same block; but I consider it best to so have them, as the whole operation of forming and finishing may be performed at the same operation.

In order to avoid the throwing out'of fins on the work, I relieve the ends of the threads, as shown in Fig. 6, at g and g and at h and h.

In order that the first effect of the formingdie mayact the more to throw the threads upwardthat is, to make the metal fill the die rather than to draw the blank and thus lengthen it--I corner the threads 1, 2, and 3, so that they may have tendency but to crease the metal. This I find a necessity in some cases, and desirable in all.

What I claim is 1. The herein-described method of forming screw-threads, consisting in passing the blank slowly in an endwise direction between a pair of converging dies, which are threaded internally and reduced in diameter from the rethreads are gradually developed on the blank.

2. A pair of screw converging dies with complementary forms or cavities therein,said cavities diminishing in size from the receiving toward the delivery side of the dies, and provided with internal threads of increasing size from the receiving toward the delivery side, whereby each portion of the thread upon the blank may be gradually developed as it is presented to the developing portions of the die-thread.

3. As an improvement in the art of forging screw-threads, the method consistingin first passing the blank between tapering internallythreaded forming-surfaces, and subsequently between forming-surfaces of smaller internal diameter having threads of constant form and size therein.

4. Complementary screw-forging dies provided with tapering internally-threaded forms or cavities to produce the crude thread, and the finishing-form of smaller internal diameter threaded in exact conformity to the re; quired screw.

5. lChe complementary dies for finishing screw-threads, having the internal forms or unthreaded recesses, F F, of semicircular section and uniform diameter, and the internal threads of uniform size throughout their entire length, whereby said dies are adapted to finish the threads for use and at the same time to maintain the screw in a perfectly straight condition.

BURR A. KENNEDY.

Witnesses:

ROBERT H. DIXON, JOHN B. KASPARI.

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