US440330A - Island - Google Patents

Description

(No Model.)

O. D. ROGERS. DIE FOR MAKING ROLLED WOOD SOREWS.

No. 440,330. Patented Nov. 11,1890.

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' UNITED TATES CHARLES D. ROGERS, OF PROVIDENCE, RHODE ISLAND, ASSIGNOR TO THE AMERICAN SCREW COMPANY, OF SAME PLACE.

DIE FOR MAKING ROLLED WOOD-SCREWS.

SPECIFICATION forming part of Letters Patent No. 440,330, dated November 11, 1890.

Application filed August 4, 1890. Serial No. 360,864- (No model.)

To all whom it may concern.-

Be it known that I, CHARLES D. ROGERS, a citizen of the United States, residing at Providence, in the county of Providence and State of Rhode Island, have invented certain new and useful Improvements in Dies for Rolling Screw-Threads on Wood-Screws; and I do herebydeclare the following to be a full, clear, and exact description of the invention, such IO as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters of reference marked thereon, which form a part of this specification.

In a patent of the United States granted to me September 20, 1887, No. 370,354,1have described and claimed a novel form of die for developing the threads of rolled wood-screws. In that die the ribs are represented as V- shaped, the Working-faces being truncated throughout their length, narrow at the coinmencement or entering end, and gradually diverging therefrom to the opposite end, at which point the grooves (alternating with the ribs) are the exact counterpart of the thread produced upon the screw by the dies. In that die the angle or inclination of the sides of the ribs to each other is constant from one end of the die to the other, although the 0 height of each rib and the depth of each groove is represented and described as varying throughout its length.

The object I have in View in my present improvement is to produce a stronger and bet- 3 5 ter die, yet one in which the ribs shall retain all the characteristics and advantages possessed by my patented die before referred to.

To that end my invention consists, essentially, of a die having at the commencement or entering end ribs and grooves of the same or a less depth than that of the grooves at the opposite or finishing end of the die. By reason of such construction the ribs are much less liable to fracture or break during the process of hardening and tempering the die. Moreover, the die when put into use will last longer, owing to the increased strength of the ribs at the front or entering end.

In the appended drawings, representing my improved die, Figure 1 shows a plan of the working-face of one die. The unshaded parts represent the faces of the ribs. Fig. 2 is a longitudinal sectional view taken on the oblique line a; 00 of Fig. 1. Fig. 3 is a similar sectional view showing a modification of the depth of the grooves and ribs. Fig. 4 is an elevation of the front end of the die. Fig. 5

is a similar view showing the back end of the die where the completely-threaded screw leaves it. Fig. 6 is a transverse sectional view taken on line t t of Fig. 1. Fig. 7 is a similar View taken through a pair of dies placed opposite to each other as in operation, showing a screw between them in the act of having a thread developed on its surface, 6 5 the section corresponding with line 0 0 of Fig. 1; and Fig. 8 is a similar section taken on line p p.

In the drawings, A designates my improved die as a whole. The parts marked aindicate the ribs adapted to be impressed into the screw-blanks surface, and the shaded parts marked 6, Fig. 1, indicate the grooves between the ribs. The grooves are filled in or truncated at the front or entering end and are V- shaped at the opposite end. The bottom 0 of the grooves may be parallel with the face of the ribs, as shown in Fig. 3, or inclined, as in Fig. 2, the depth being greatest at the back end of the die. In fact the bottom or depth of the grooves need to be considered only with reference to the gradual development of the screw-threads in a radial direction; or, in other words, the depth of the groove at any point slightly exceeds the height of the metal raised from the blank measured from the root of the thread at a corresponding point. Therefore the bottom of the grooves may be inclined substantially as indicated by the broken line m, Fig. 2.

The angle of the inclined sides of the ribs a is constant and uniform throughout the length of the die, but the width of the face or top of the ribs is constantly Varying throughout or from end to end of the die. 5 The face of the rib at the end where the rolling commences should be made as narrow as is consistent with its strength, in order that it may be required to displace but little metal as it enters the blank. To facilitate its en- IOO trance, the top may be slightly chamfered or rounded, as indicated by f. I have found that the ribs when the grooves are made to an extreme depth at the entering end, as hereinbefore stated, sometimes break while in action upon the blank, because then the leverage produced by the lateral pressure of the metal upon the ribs is excessive. Another objection to an extreme depth of the grooves is that in the process of hardening and tempering the die the root of the narrow ribs are much more liable to fracture at such point. In View of such defects, and in order to overcome them, I have very materially reduced the height of the ribs at the entering end, as shown.

In lieu of making the faces of the ribs to at a constant inclination throughout the length of the die, they may be curved, the curvature somewhat approximating that of a portion of a hyperbolic curve; or the die itself may be made in sections longitudinally, the inclination of the series of ribs of one section varying slightly from its adjacent section, substantially as set forth and claimed in my United States Patent No. 430,237, issued June 17, 1890.

The grooves Z) and the corresponding ribs 11 may be cut by a revolving milling-tool, the sides of which give the required inclination to the sides of the ribs, the die-blank being first blocked up at the proper angle, if desired, so that the cutters will cut the grooves at the varying depth, or as shown in Fig. 2. After the cutting-tool has cut one side of a groove the tool is set over and again operated so as to form the opposite side of the groove, the blank at the same time being forced along past the cutter. After the two sides of the several grooves are cut the standing stock intermediate of the adjacent sides of each groove may be cut away or routed by a suitable cutting-tool, thus completing the operation.

A manner of forming the threads of ascrew in a suitable machine, so as to travel back and forth past each other, two similar dies Abeing used with the ends reversed. A screw-blank is then placed and held vertically in the space between the opposed ends of the dies, and as the dies move simultaneously to the right and left they engage the blank between them and roll it axially until the opposite ends of the dies pass each other, when the jaws of the stationary holder open and the screw drops from them. At the commencement of the operation the narrow ends of the ribs a of the dies are forced into the metal to the maximum depth required, or, say, nearly to the dotted line m, Fig. 2, at the corresponding end of the dies, and as the rolling pro gresses the metal between the ribs is more and more compressed and gradually expands into the grooves 12 of the dies until, at the end of the operation its fills them and the thread is completed.

I claim- A die for raising the threads of a screw radially from a screw-blank by rolling, having at the entering end narrow or thin ribs to enter the metal to the required depth, but increasing in width to the opposite end, with the intervening grooves of the same depth or slightly greater at the entering end than the depth of the groove in the blank, but increasing in depth to the opposite end to correspond with the increasing height to which the metal is raised as the rolling progresses.

In testimony whereof I have affixed my signature in presence of two witnesses.

CHARLES D. ROGERS.

WVitnesses:

CHARLES HANNIGAN, GEO. H. REMINGTON.

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