US461620A

US461620A - Island

Info

Publication number: US461620A
Authority: US
Publication date: 1891-10-20
Anticipated expiration: 1908-10-20

Description

(N0 lfiohel. 3 Sheets Sheet 1. O. D. ROGERS. DIE FOR ROLLING SGREW'THREADS.

Patented Oct. 20, .1891.

INV EN TUR- WI TNEEIEEE. 6%

(No Model.)

\ Patented Oct. 20,1891.

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' 0-. D. ROGERS.

OOOOOOOOOO ING gCRE'W THREADS.

Patented 00h 20,-;1891.

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3,, fiiwiw t WW M- j M a A -wfi UNITED STATES PATENT OFFICE.

CHARLES D. ROGERS, OF PROVIDENCE, RI-IODE ISLAND, ASSIGNOR TO THE AMERICAN SCREIV COMPANY, OF SAME PLACE.

DIE FOR ROLLING SCREW-THREADS.

SPECIFICATION forming part of Letters Patent No. 461,620, dated October 20, 1891.

Application filed March 10, 1891. Serial No. 384,517. (No model.)

To ctZZ 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 usefulImprovernents in Diesfor Roll.- ing Screw-Threads; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable to 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 thereonfivhich form a part of this specification.

My invention has relation to dies such as are mployed in forging (cold) the screwthreads upon screws by what is termed the rolling process, the class of screws to which the invention more especially appertains being known as wood-screws. Rolled woodscrews, even though made of the same wire, vary greatly in their holding-power according to the form or shape and inclination of the ribs and grooves of the thread-forming dies. The form of the ribs of such dies transversely as first employed in thread-swaging was, I believe, V-shaped, the shape and area of each rib being uniform throughout its length. The action of such dies upon a screw- 0 blank is to elongate it, the diameter of the threaded portion being the same as that of the wire itself or unthreadedpart. I would state that the die just referred to was employed to produce the threads on small ma- 3 5 chine-screws having fine pitchsuch, for example, as are used to secure the knobs or handles to the spindles of door-latches. A later example of thread-rolling machines and dies is that shown in a patent of the United States, granted to Clarke and Harvey, October 7, 1884, No. 306,132. In that patent the ribs of the dies cross-sectionally are V-shaped at the commencement or entering end, but are gradually transformed into a truncated 5 shape. In operation the ribs are gradually forced into the screw-blank axially from the commencement to the end, thereby producing a groove which is gradually deepened and widened, the metal being forced outwardly from under the ribs of the traveling dies in the form of ridges or threads which gradually increase in diameter. In that die the angle or inclination of the sides of the ribs varies throughout its length-that is to say, the included angle formed by the sides of adjacent ribs at the entering end of the die is much greater than that at the opposite end. Consequently its action uponthe metal isirregular. The screw is both enlarged laterally and longitudinally during the thread-forming oper- 6o ation. There are still other forms of dies adapted to swaging screw-threads. I have invented one wherein the inclined ribs and also the grooves thereof transversely are uniform in shape and area throughout. Such dies, however, cannot well produce screws having the threads raised above the normal surface of the blank to the extent necessary or essential to Wood-screws adapted to be inserted into wood by a screw-driver. Therefore I employ 7c the dies in making what are termed drivescrews that is, screws having multiple threads and coarse pitch. Screws of this class and as made by my said dies are readily driven into wood by the blows of a hammer and turn axially While being driven.

In United States Patent No. 370,354, granted to me September 20, 1887, I have shown and described dies for forming the threads upon wood-screws by rollingthe blanks between them and raising the metal to form the thread radially from the body of the blank without extending the blank lengthwise. In using 5 the dies the pressure upon the metal toward the axis of the blank is limited to the commencement of the rolling operation and to a comparatively small part of the metal displaced. The work of raising the threads is mainly performed by the inclination of the adjacent or lateral sides of the ribs, such in- 0 clination being constant from one end of the die to the other. The face of the ribs at the entering end, where the rolling commences, is quite'narrow, in order that they may be re quired to displace but little metal. The ribs 5 gradually increase in thickness laterally from the commencement to the end of the die, the faces thereof being flattened or truncated throughout. A pair of these dies in operation produces a gradually-developed screw-thread, because at each successive revolution of the blank the metal lying between the constantlyvarying (in thickness) ribs is more and more compressed laterally and at the same time gradually expanded radiallyinto the grooves of the dies until at the end of the operation it fills them and the thread is completed. The

thread cross-sectionally is solid and wedgeshaped, being quite thin at its base or root where it joins the core and sharp at the point or edge. In these screws, the bottom of the groove being parallel for its whole width with the axis of the screw, the top of the ribs must be flat and the metal of the blank at the bottom of the groove must be displaced by the ribs of the die to the full width of the groove by a kind of shearing action at the bottom of the groove.

The present invention is an improvement of the above-mentioned die and is designed to act by a lateral pressure of the metal of the screw-blank and its radial expansion, as with the dies just referred to, but by an easier displacement of the metal, with less or none of the shearing action at the bottom of the groove of the screw, as above explained, in the use of fiat-faced ribs. I accomplish this object by rounding transversely the top of the ribs of a die for a part or the whole of their length. The eflfect of this is to reduce the width of the inclined sides of the ribs, which act upon the metal laterally as the thickness of the ribs transversely increases, and to leave a portion of the metal undisturbed, which would be displaced to form the angle at the bottom by flat-faced ribs, and a groove rounded at the bottom is produced instead of a flat-bottomed groove, forming an angle with the sides of the threads or ribs of a screw.

In the annexed three sheets of drawings illustrating mypresentimprovements, Figure 1, Sheet 1, represents a plan of the working face of one die. The lightly-shaded parts indicate the faces of the ribs. Fig. 2 is a longitudinal sectional view taken, say, on line m m of Fig. 1, showing the ribs constantly decreasing in height. Fig. 3 is a similar sectional view, the height of the ribs being constant throughout. Fig. 4 is a transverse sectional View taken through a pair of the dies at or near the finished end, showinga screw in partial section between them. Fig. 5 is a plan view of one of the ribs of the die detached, one portion of the ribs face being flat or truncated, the other being rounded, as indicated by the shade lines. Fig. 6 is a similar view of a rib, its face being rounded throughout its length. Figs. 7, 8, and 9 are cross-sectional views of the rib, taken, respectively, on lines a: at, w w, and o o of Fig. 5. Fig. 10 is a transverse sectional view taken on line 00 a: of Fig. 6. Figs. 11 and 12 are similar sectional views showing modified forms of the ribs. Fig. 13, Sheet 2, is a longitudinal sectional view showing my improved die bent to a circle or curved in lieu of being straight. Figs. 1a and 15 are transverse sectional views showing the form of die-ribs as patented to Harvey, before referred. to. Fig.

16 is a plan view of one of the last-named ribs provided with a rounded face. Figs. 17 and 18 are cross-sectional views thereof, taken, respectively, on lines a; a: and o o of Fig. 16. Fig. 19 is a longitudinalsectional view, enlarged, taken through the center of a gimletpointed wood-screw provided with my improvement. Fig. 20 isa similar view of the screw having a double-thread and unthreaded spur-point. Fig. 21, Sheet 3, is a plan view of the working face of a die embodying my improvement. The shaded portions indicate the ribs having rounded faces, the general arrangement of the ribs being in the form of steps, or terraced, substantially as represented in United States Patent No. 441L329, granted to me November 11, 1890. Fi s. 22, 23, 24, and 25 are cross-sectional views taken, respectively, on lines a a, b b, c c, and at (Z of Fig. 21. Fig. 26 is a plan view of a rib enlarged, having a uniform width and shape throughout its length; and Fig. 27 is a transverse sectional view taken on line 6 c of Fig. 26, showing the relation of adjacent ribs to each other.

A in the several figures indicates my improved die as a .whole. The ribs of the die are designated by a an d the grooves or spaces lying between them by b. The grooves and ribs at the commencement or entering end of the die are substantially V-shaped, the angle or inclination of the adjacent sides of the grooves being practically constant from one end of the die to the other, as represented in Sheet 1 of the drawings. The height of each rib a may vary throughout, as indicated by Fig. 2, or they may be uniform in height, as in Fig. 3. In any case the width of the face of the rib varies, being narrowest at the entering end of the die and widest at the opposite or finishing end. Such width of ribs may vary constantly and gradually, as shown in Fig. 1, or they may be in the form of a series of increasing steps, as c c c c, Fig. 21.. The face of the rib at the entering end should be made as thin or narrow as is consistent with the work imposed upon it. The face thereof for a portion of its length may be flat or truncated, as at to, Figs. 5 and 7, such fiat portion being joined to a gradually-increasing rounded part, (see Fig. 5,) the latter part terminating in well-rounded ribs, as clearly indicated by Fig. 9, which represents, enlarged, a partial cross-section taken on line in a: of Fig. 1 and also on line '0 0 ofFigs. 5 and o. The face of the ribs 0. may be rounded throughout, as shown by Fig. 6, and its sections as cc, to w, and o 0 represented by Figs. 10, 8, and 9, respectively. Obviously the shape of the grooves b gradually changes from the V form at the front end, Figs. 7 and it), to the opposite or finishing end of the die, where the grooves diverge laterally in curved sides, Figs. 4 and 9, which are the counterpart of the sides of the screw-threads t. (See also Figs. 18 and 25.)

In the (llarke and Harvey die before referred to, the oblique ribs and grooves are uniform in height throughout the length of the die; but the angle or inclination of the sides thereof constantly varies, as indicated by Figs. 14 and 15. The former figure shows enlarged, cross-sectionally, a portion of the die at the entering end and the latter a similar figure taken at the opposite or finishing end. The rib a is V-shaped at the front, its face being sharp and gradually widening therefrom to the other end, (see a Fig. 15,) thereby gradually changing the angle of its sides until a sharp V-shaped groove 12' is produced, Fig. 15, which is a counterpart of the thread. The ribs and grooves of such a die may be rounded, as indicated by Figs. 16,17,

and 18, the latter then representing ribs to and grooves 19, substantially like those shown by Figs. 4, 9, and 25. Although dies having ribs and grooves, as shown by said Figs. 16, 17, and 18, may be employed to swage or roll the threads of screws, I preferably use dies having the angle or inclination of the sides of the ribs a substantially constant from one end of, the die to the other, Figs. 1 to 10, because the threads thus produced are more gradu ally developed and more homogeneous, the percentage of loss is less, and the work is accomplished with less power.

The die A may be secured to a revolving cylinder or carrier m, Fig. 13, the operation of rolling the screws then (if combined with a stationary die) being substantially as set forth in the Patent No. 306,132, granted to the said Clarke and Harvey by the United States, hereinbefore referred to.

In Figs. 11 and 12 the bottom of the ribs a are rounded as well as the faces. The last or finishing section, however, would be substantially as represented by Fig. 9. An advantage resulting from thus filleting the root of the ribs for a portion of their length is that it increases their strength in a lateral direction.

A die provided with ribs a Figs. 26 and 27,

'having a uniform width and area transversely throughout their length, may be employed; but the ribs cannot produce a gradually-de veloped screw-thread as compared with my improved die provided with developing ribs a, because the grooves b Fig. 27, themselves are uniform throughout.

3 indicates my improved wood-screw, the threads t thereof being produced by rolling by means of the dies A, hereinbefore described. The shank or unthreaded portion 8 of the screws I make slightly tapering orconical. This is performed in the dies simultaneously with the operation of upsetting the metal therein to form the heads 72.. Practically I prefer that the diameter of the shank at its intersection with the head shall be substantially the same as the diameter of the threaded portion. The threads t are filleted at the bottom 25, thus adding to their strength in a-lateral direction. The screws may be gimletpointed, as at 19, Fig. 19, or the point-thread may be wholly or in part omitted, thereby producing a spur-point 19, Fig. 20.

The ribs to and grooves b ofmy improved die A may be cut by a revolving milling-tool or a series of them, having the proper form to give the required inclination or bevel to the sides of the ribs. The die-blank is first elevated at one end and secured to a reciprocating table or carriage in such manner that its longitudinal axis in a horizontal plane is not parallel with that of the moving table, which latter carries the blank past and in contact with the tool. The rounded form given to the face of the ribs may be done simultaneously with the cutting of the grooves; but practically I prefer to first truncate them by the tool just referred to, after which the ribs faces are rounded off by another cutter or cutters or by other suitable means. The dies are subsequently hardened, thereby rendering them ready for use.

The action of the dies in forming the filleted threads t t of a screw may be described as follows: Let it be assumed that a pair of the dies A, with the ends reversed, are arranged to move back and forth past each other in a suitable machine, or substantially as shown and set forth in United States Patent No. 389,168, granted to me September 4, 1888. To roll a screw the blank is introduced vertically between the ends of the separated dies, (the latter then being at the end of the stroke or on the dead-center,) which immediately seize it from opposite sides. The blank is rolled axially by the action of the two traveling dies until they pass each other, when it drops from them completely threaded. At the commencement of the operation the narrow ends it of the ribs a of the dies are forced into the metal to the maximum depth required, the lateral separation of the working faces of the oppositedies being constant throughout and corresponding to the diameter of the root or core of the screw. As the rolling progresses the metal seized between IIO each pair of the ribs above the curved portion of the ribs is compressed and at the same time gradually expanded into the groove Z) of the dies, until at the end of the operation it fills them and the thread 2525' is completed, the threaded portion then being substantially as represented by Figs. 4, 19, and 20.

I claim as my invention 1. A die for raising the threads of a. rolled screw radially from a screw-blank by compressing the metal for the thread laterally between the converging sides of the ribs of the die and having the faces of the'ribs rounded to form a concave bottom of the grooves of a screw, said ribs being narrow at the end where they commence to form the thread, so that they may be forced at the commencement of their action into the metal to the depth required to form the body of the screw, and increasing in width act laterally upon the metal between the ribs and force it into the grooves, Which at the end of the operation give it the precise form required for the thread.

2. The die A, substantially as hereinbefore described, for raising the threads of a rolled screw radially from a screwblank, the work ing, surface of the die being provided with a series of obliquely-arranged expanding or developing ribs to, having rounded faces and I0 converging adjacent sides, each rib being narrow at the end where it commences to form the thread and increasing in Width transversely to the opposite end of the die.

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

CHARLES I). ROGERS. \Vitnesses:

CHARLES IIANNIGAN, GEO. H. REMINGTON.