US2483186A - Apparatus for rolling screws - Google Patents

Description

Sept 27, 1949. w. A. DE VELLIER 2,483,186

APPARATUS FOR ROLLING SCREWS 1N V EN TOR.

Sept. 27, 1949. w. A. DE vELLlER APPARATUS FOR ROLLING SCREWS 4 Sheets-Sheet 2 Filed Oct. 2. 1945 INVENTOR. wczzzzpe gmane- Sept 27, 1949- w. A. DE VELLIER APPARATUS FOR ROLLING SCRWS 4 Sheets-Sheet 5 JNVENTOR.

Filed Oct. 2, 1945 Sept. 27, 1949. w. A. DE vELLlER I 2,483,186

APPARATUS FOR ROLLING SCREWS Filed Oct. 2, 1945 4 Sheets-Sheet 4 l 5y 'WWW a. 9AM

Patented Sept. 27, 1949 APPARATUS FOR ROLLING.s'cREws4 Y william A. De veuier, New veran. Y., assigne;

to New Process Screw Corporation, Waterville, Comi., a corporation of Delaware .Applieetienoeteber 2, 1945,v sefieilveieiasi",'f

An object of my invention comprises the modivflcation of said method to positively produce the right predetermined point, and in practice to successively produce the same shaped points on the double threaded screws shown and described in said patent,'in other words',` my present invention involves improvements' or renements in the method of rolling'screws described in said patent. As stated in said patent, thenature of the point can be changed to that of the various species shown therein and other species by variations in the shape and' amount of excess metal on the point forming portion of the blank.

In employing said invention in commercial practice, even with the same amount of excess metal on the pointed portions of the screw blanks, slight variations in the shape of the points in successive screws were produced. All matters of prior known shop practice were carefully checked, namely the circumference and dimensions of the blanks were measured, and the method of making the dies to the right theoretical dimensions and the method of setting the machine and dies to make the screws roll'between the dies to make double threaded screws inv accordancewith the showing in my copending application for patent, which is now abandoned, Apparatus for rolling double threaded screws, S. N. 598,675, led June 11, 1945, of which this is a continuation in part, carefully checked and still variations in the points of the screws occurred. It remained for the present inventor to further visualize the fact that in order to make a predetermined point and successively roll screws having substantially identical predetermined points, it was necessary to correctly register'the pointed portion forming portions of the screw blanks at the right height between the pointed portion forming portions of the die cavities by supporting a blank at the right.

height at the initiation of forming threads on said blank and supportingsuccessive blanks' as they are rolled on said dies at the same-.suitable right height at their respective initiations of forming threads on said blanks. It was. onlyaftersuit- 2 Claims. (Cl. '80-8) able means were provided for this purpose and the thorough realizationfthat this'method'was necessary that the present invention was evolved and screws having substantiallyidentical pointed portions successfully rolled successively. yI discovered that once the threads are started right, if the blanks are of a correct circumference and other dimensions, `the dies carefully made to correctV theoretical measurementsand the machine and dies correctly Vand properly adjusted, screws having substantially"identical predetermined points maybe rolled if theirblanks are initially corr'feetly aimed tobe initially correctly grabbed at thel right po'intsor hightand that the screws will roll kat exactly the same "height'they are started' at throughout the remainder of their passage through the dies tosuccessively provide the right threads andthe right points. I discovered that it wasrstnecessary to make the blanks andI dies right'in accordance with prior shop" practice and the showing in my said application; S. N; 598,675, and this application, second 'to provide them with an adequate and proper adjustment'as shown in my said application vand this application; 'and finally to aim or start the blanks at the right heightas shown 'and claimed in this application, and that'screws having substantially identical points' wouldbe successively produced.

In 'accordance with my improved method I positively support the lower ends of said blanks from below, such as lby a bottom stop attached to one of the rolling dies orsuitably supported between them. I have found that by varying' the height of the bottom' stop' the type of point may be 'varied of the double'thre'aded screws shown in De Vellier Patent 27,314,391`'aforesaid within certain limits. Varying'the heights of the bottom stop will varythe'type of points produced, the shape or quantity of "excess Vmetalon the pointed portions of the blanks remaining constant. Thus while' for any substantial change in the nature of the point a variation the shape and the amount of metal on the pointed portion of the blank is essential, minor ,compensating or adjusting vchanges in the point to produce commercial points may be made simply by corresponding changes in the adjustment of the bottomstop.

I support the blanks from below preferably by means of an adjustable bottom stop which positively abuts and supports the .lower ends of 4the screw blanks during this period. As an adjustable bottom stop is employed the point forming portions. off the screw blanks may be relatively raised and lowered relative to the point forming portions of the die face cavities to vary the type of points produced.

Supporting the die blanks from below at this period however has an additional advantage. Quite citen in practice screw blanks are not of uniiorm length and some are often longer than others, thus ii the blanks are not supported from below, their lower ends or point forming portions will register at dierent heights relative to the point portion forming portions of the dies resmting in slight changes in the points produced. However, when the blanks are Asupported from below as by means of an adjustable bottom stop, the pointed portion forming portions di the blanks will always register at the same place or height relative to the pointed portion lforming portions oi' the dies so as to positively insure the successive production of substantially identical points. a little longer than the others, the only diierence in screws produced is only 'a slightly longer unthreaded portion von the `screw Shanks well within standard tolerances.

Further objects of Ymy invention relate to the Vprovision oi a -novel typeof apparatus to carry 'out my improved method.

These and such other objects of my invention as may hereinafter appear will `be best Vunderstood irom a Adescription of the embodiments thereof shown in the accompanyingdrawings.

in the drawings, Figs. 1-12 `illustrate my invention with Athe screw blanks being supported from belowV during the initiation of forming threads thereon.

Figs. l and 2 are face viewsrespectively ofthe stationary 'and movable dies for rolling double threads on the'screw blanks, Fig. 1 additionally illustrating Vscrew blanks at different stages of rolling oi the screw threads thereon, the successive positions of the blanks indicating the shape of the threads at substantially the positions shown thereon as the blank is being rolled thereacross, and the preferred type 'of adjustable bottom stop employed by me for Vsupporting the screw 'blanks from below 'during the initiation of forming thethreads thereon.

Fig. 3 is a, perspective view of Vmy improved stationary vdie Vprovided Vwith an "adjustable b'ottom stop as shown 'in Fig. 1.

Fig. 4 is a fragmentary reverse plan Vview showing the details voi' theadjustable bottom stop shown in Fig. 3.

Fig. 5 is a side elevation of a completed double vthreaded screw fabricated in the'manner shown in the previous drawings.

Figs. 6`10 are vertical sectional views "taken respectively through 'the 'two dies along the relative positions ofthe blank as it progresses to its nished state showing the 'blank in elevation, Fig. 6 being a vertical sectional View approximately at the initiation of rolling, position a, with the blank supported by the bottom stop, Fig. 'l being a vertical sectional view substantially at the second position b shown in Fig. 1 reading from left to right, Fig. 8 being la vertical sectional view substantially at the third .position c shown in Fig. 1, Fig. 9 being a vertical sectional view substantially at the fourth position d shown in Fig. l, and Fig. 10 being a vertical sectional view taken substantially at the completion of the rolling of the screw threads thereon, position e.

Fig. 11 is a perspective partially exploded view 'of the two dies shown in Figs. 1 and 2.

i' one screw blank happens to 'be Fig. 12 is a plan view of a suitable die rolling machine with my improved dies mounted thereon having suitable means for adjusting them to provide the oppositely inclined grooves thereoi continuously opposite each other t0 accurately roll double threads.

n the drawings, wherein like characters oi' rei'erenee generally indicate like parts throughout, 'it generally indicates a double threaded screw constructed in accordance with my invent'ion as shown in Fig. 5.

As statedhitherto, my present invention covers improvements in the Method oi' rolling threaded screws described in my former Patent 2,3l4,391.

Asstated in vsaid patent, it has been customary in the prior art Vto form pointed portions it oi` conical shape on the screw blanks 98 prior to rolling threads thereon. Great diiiculty has been experienced in nding enough metal from suoli a conicaiiy pointed portion oi the shank to -iorm threads extending to or beyond the tip 'iii oi said conically pointed portion where it is desired to roll double threads' as they require considerable metal.

Ivy invention is adapted for use in rolling double threaded screws to successively produce unii'crm predetermined vpoints thereon. My improved screw has the usual head Ai2, the shank iii and the tapered pointed portion it or the shank terminating in the tip 16 and the continuous double threads 13 extending spiraily downwardly through at least a portion of said shank 'it and said tapered pointed portion 15. Each 'thread 18 preferably tapers outwardly to a sharp continuous spiral cutting preferably razoriike edge 1S oi substantially'even heightthroughout the shank 7d and of progressively decreasing height in said'tapered portion i5 of the shank.

Employing my invention, the lower ends oi said threads may form sharp incising means 82 projecting substantially axially downwardly oiV the pointed portion 'i5 of said shank.

My invention valso involves a novel method of rolling double Ythreaded screws, which comprises after pressure shaping or otherwise forming a length of stockV into a blank 98 having a head 'l2 on one end thereof Vand an irregular shaped pointed portion 9S having an excess of metal IDD thereon greater than required for a conically 'pointed portion 128, as shown in Figs. 1 and 6 on the opposite end thereof, rolling continuous double threads T3 on the other end of the shank 'i4 adjacent to and on said pointed portion t9 and displacing said excess metal I on said pointed portion 99 to form it into the pointed .portion l5 of the iinished screw and to form continued threads 94 on said pointed portion 15, each 'terminating in 'sharp incisingmeans 82 projecting substantially axially downwardly of said pointed portion 15. The irregularly shaped pointedportionfg!) having an excess of metal lili) thereon greater than required for a conical pointed portion 128 may be formed in any suitable manner, if desired in a separate pointing step, -as shown in my Patent No. 2,314,390. I have found, however, that while the formation of a vtrue conically pointed portion 128 has been diicult in the header, my limproved pointed portion 9911s` of vsuch irregular shape that it may be readily vformed in 'the headen'preferably 'in the initial blow rfor roughening the head as shown in `my 'Patent No. 2,314,391, or the irregular shaped pointed portion `99 may be made inany Asuitable fashion. f

:"he threads '|8 may be rolled on the screw blanks S in any suitable manner, such as in the manner shown in Patent No. 2,314,390 aforesaid, by true radial extrusion. Commercial results, however, may be obtained by rolling them in the type of dies shownv in the accompanying drawings, constructed to roll double threads by providing groove means |04 in said dies having a suitable included angle and a pitch angle of from substantially 12 degrees to substantially 22 degrees. .I have found that suitable pitch angles for. rolling double threaded screws vary from substantially 12 degrees to substantially 22 degrees, namely from substantially 12 degrees for a No. 2 screw to substantially 22 degrees for a No. 13 screw. I have found in practice that if angles belowthes'e amounts for the respective size screws be employed in the dies that it is impossible to roll double threads thereon, single threads only being produced. I have also found that if the angle is increased substantially above these amounts for the respective size screws that more than two threads will be rolled thereon. With this type of rolling dies the excess metal |00 is forced or extruded during rolling axially downwardly as well as radially outwardly over the sides ofthe pointedportion 99 of the shank and even beyond the tip "F6 of said simultaneously formed pointed portion l5, if desired, to form the threads 94 of decreasing height terminating in the sharp-incising means 82. It is thus obvious that the amount of excess metal |00 provided may bevaried, as well as the method and amount of rolling varied to produce these different results. When the desired type of screw has been decided upon, the amount of excess metal |03 provided at the pointed portion 99 of the blank 9S and the nature and the amount of rolling may be predetermined so as to continuously reproduce the same type of screw, the amount of excess metal. |00 depending, therefore, upon the desired shape 'of the incising means 82 desired in the finished screw, the incising means 32 of the desired predetermined shape being produced by variations in the amount of excess metal lila and the type of and the amount of rolling employed. As stated, if desired, the ends 82 of the threads may terminate slightly above the tip 'i5 of the pointed portion 15 of the screw shank. While I preferably roll said threads 94 down to an incising lpoint or blade, a novel desirable type of screw maybe produced if the threads are not rolled down to a single point or a single blade, but left terminating in spaced incising means 32, on each side of the pointed portion 'l5 of the screw, in whichthe screw may initially bite into the wood or other material attwo points or portions, tending initially to more evenly align it and provide a self-centering screw as shown in my Patent No. 2,314,391.

I have shown ink Figs. 1-4, and 6 to l0 suitable types of dies .for rolling the double threads i8 extending at least to the extreme tip 15 of the pointed portion 'l5 of the shank 14 in accordance with my invention. These dies comprise the usual stationary die |30' and the die |32 movable relatively thereto in a standard type of screw rolling machine, a suitable type being shown in Arena Patent 1,912,879 and another type in Fig. 11. Each die |30 and |32 has a face |34 comprising a continuous cavity |36 having a flat shank `forming portion |46 and a pointed portion'forming portion |40 tapering outwardly to the Vsurface of said die beyond said cavity |36,

,Each face |34 is provided with continuous thread forming groove means |04, each preferably ter-v minating in a sharp intaglio ridge' |06 formed bythe sides thereof meeting in a sharp peak, extending obliquely thereof at spaced distances throughout the height of said face throughout the shank forming portion |45 and said pointed portion forming portion |40. The groove means |04 are of substantially even depth along the axis of a screw blank interposed transversely between said dies in use in said shank forming portion |46 and of progressively decreasing depth in said pointed portion forming portion |40 as may be seen in Figs. 6-10. In the embodiments shown, each groove means |04 is also of progressively decreasing depth and width along the length thereof and the successive groove means are of progressively decreasing depth and .width throughout the length of the -cavity forming cooperating lands |48 between said groove means, of inversely increasing relative width .throughout the height of said face through said shank and f screw pointed portion forming portions. Thus each res ective groove means |04 is of substantially equal depth in said shank forming portion and of progressively decreasing depth in said pointed portion forming portion along the axis of a screw blank interposed transversely between said dies when mounted on a rolling machine in use. In use, the dies |30 and |32 are so mounted that their entire faces |34 remain at a spaced distance from and inclined relative to each other with their respective groove means |04 oppositely inclined, to roll preferably by both axial and radial extrusion double screw threads on the screw blank 98 rolled between them with similar portions of similar grooves |04 in each die continuously opposite similar portions of respective oppositely inclined grooves |04 in the opposite die along the respective successive lines of contact of said dies with said screw blank.

In order to provide the double threads 18, the groove means |04 have a pitch angle varying from substantially 12 degrees to substantially22 degrees, in the manner hitherto explained. I concave the face |34 of each diev with a screw blank cavity and suitably form the thread forming grooves |04 in said cavity, preferably by a suitable hob or milling cutter. It will be noted that the lands |48 between the grooves preferably progressively widen and the grooves |04 themselve preferably progressively narrow lengthwise of the dies. The various positions a, b, c, d and e that a screw blank assumes in being rolled .are shown'in Fig. 1

andFigs. 6-10 to illustrate diiferent stages in the act of rolling the threads, the threads being'initially roughened out at a, the threads 18 themselves progressively narrowed from b to e andthe lanes |52 between the threads 'i8 progressively widened from b to e. It is obvious however that the shape, depth and width of the groove means may be suitably varied to produce different types of screws.

A close inspection of Fig. 1 reveals how the excess metal |00 is displaced axially to form the threads 94 from the pointed portion 99 merging into the incising point 82 and to shave down the pointed portion 99 of the screw blank 93 into the pointed portion 15 of the screw. A close inspection of Fig. 1 and Figs. 6-10 illustrates how the length of the screw increases at the different stages as the threads are formed thereon.

As stated hitherto, said dies must be mounted vso that their entire faces remain at a spaced distance from each other with their groove means |04 oppositely inclined as shown in Fig, 12 to roll preferably by axial and radio-t extrusion, as suggested in Fig; l, doublel screw threads `on ay screw blank rolled between them with similar portions or similar grooves Miltoneach die A|510 and |232 continuouslyv opposite similar portions. of respective oppositely inclined grooves. W4 in the opposite die along the. respective successive. lines. of contact' ci said dies with said screw blanks .to produce the double screw threads. It thus obvious that each cliemust be adjustable not only vertically within.v its holder but also so. .each end thereof maybe adjusted vertically or tiltably relative to the other end. Inaddition, it is preferable if one of the dies preferably the stationary die |32 be tiltable horizontally away from the vertical plane ot the other so that there will be greater space between the dies at` the start of the rolling. In other words, so that the stationary die maybe pifvoted horizontally relative to itsv outer end to give it proper bite and pressure on'. the blank to start. the blank rolling .between the diesA and atV the same time starting to rolll the threads. It isv obvious that each of these adjustments may be made preferably by the trial andk error method on individual screw blanks until the proper adjustment is made when the rolling machine may be run continuously to produce the screws.

I. have shown in Fig. 12 a rolling machine |53 equipped with both of these adjustments, namely the vertical adjustment to align the grooves of the dies exactly opposite each other throughout the rolling cycle so thatthe, dies may assume the vertical positions shown in Figs. 6-10 with the lg'rooves continuously opposite each other for rolling double threaded screws and so that there may be room at. the feeding end of the diesV for insertion of the screw blanks 98 therebetween with the stationary die |35 inclined relative to the movable die |32- to compress the screw blank and hold it in position during rolling and provide the greater spacing i543 shown in Fig. 6 at the point a, successively decreasing through Figs. 7, Si and 9 as shown at |55, ld and itu respectively for the positions b, c and a. to the narrow spacing |60 shown at the position ein Fig. l0.

Asishown in Fig. 12 the movable die |32 is sui-tably mounted in the movable die block |62; The facev of the movable die 'block |i2 is provided with a. vertical groove ISQ for receiving the movable die |32 having an inwardly tapered inner end wall |66 adjacent the cooperatingly tapered inner endwall m of the movable die |32. The movable die block |i2 is verticallych-anneled to receive the movable die clamp. ld, the channel |10- being wider than the clamp H58- to permit the inward and. outward adjustment thereof. The inner wall of the clamp |68 adjacent its face is provided with the inwardly tapered end. wall |12 abutting the inwardly tapered outer end wall |14 of the movable die |32'. rEhe movable die: block |52 forms .a ram |62 which may be moved `inwards and outwards by the connecting rod |16 mounted on the crank pin lid eccentric oi' the drive shaft .|802 of the roll-ing machine to reciprocate the movable die vblock |62 inwardly and outwardly for rolling the screws. The. outer end |182 of the movable die block' beyond the clamp 568i is provided with an inwardly projecting horizontal threaded hole |184 to receive the. adjusting bolt |86 projecting inwardly of they hole |84 fromthe outer walll of the die block,v the inner end of which .is adapted to .abut the die clamp |58 to clamp it against the outer end of the stationary die |32 to hold the die |32 in adjusted position clamped against rthe walk 66 of the die block |62 as shown in Fig. 71;

1:2. morder-that the grooves EM of the movable die 32: may be vertically andor slightly aneth larly adjusted to be critically` opposite the grooves Hierin the. stationary die4 i3d' the movable die: |322 is usually of less height. than its groove |64, proriding suitable space. below the movable dieA L32 for this: purpose. Thus when it is desired to. ad.- just. the.- entire die B32 the bolt. ll may/befunloosened and the entire die |32 raised. and lowered within the. groove4 |54? and when is desiredv to the inner end |9l relative tothe: outer end |92 or vice versa. theeholt |86 may be unloosened and the respective end raised. .or lowered relative to the: other prior to. again tightening the. bolt tad. In the preferred. embodiment shown there.- fore. the, entire adjustment. of the die is. effected by7 the end :clamp for the die provided by' the. die: cla-mp tf and its; adjusting bolt, |185;

The stationary die. |3|lv is similarly adjustable in the stationaryA die. block 94. Eor this: pui:- pose. the stationary die block |234 is separated transversely as; at tile near the outer end thereo to provide .the movable portion .M81 adjustable relative to the stationary portion l9afof; the stationary die block H84. The. stationary die. black is' also .provided with the. vertical groove 2HE for hol-.ding the stationaryy die. |30- which has. an. in.- wardly tapered end wall 202: at inner end, in the solid portion of the die' block and an inwardly tapered end wall 206., at. its outer end in the movable portion |98 .of the die block.. Both the mov'- able and stationary' portions: lill-u and |85 civ the stationary die.4 block |94 are provided with the horizontal threaded-1 holes. .201i and 2119 respectively forming a continuous hole for the insertion of the adjusting holt 210 therein. The inner end of the bolt Emis suitably anchored as ai: N2 in the: stationary portion |95 of. the stationary die block loll and it is apparent that the. screwing and unscrewing of the vholt will move. the movable portion. l 98- relative to its stationary portionV |139 to. permit easy vertical adjustment ofA the sta.- tionary die |36 in the die block |94 either the whole die itself or each end thereof as explained for the movable die by loosening the. adjusting bolt. 21B and moving the desired portions of the die and again clamping' the adjusting bolt 2li? when the. die is in its desired position.. ItI is;.-ap; parent. thatv with this` adjustment for the movable and stationary dies that the respective.V groove means' IM may be suitably aligned and that by providing the end clamps alone vto solely clamp the die rany supporting' shims thought necessary by' the prior art are eliminated.

. vas stated, in the embodiments shown, I also preferably provide means Vto tilt the stationary die from a. horizontal plane on its' outer end. |93 asa pivot although either .or both oi said dies may be so tilted if. desired. The.` stationary die block |94 is mountedv on the die bed ZM. The die bed 214' is provided. with the threaded bolt receiving holes 2| S and the die block |94 is pro.- vided with cooperating transversely elongated slots M8'. Bolts 22o are provided' for clamping the stationary die. block |94 .to its. bed 2||ttrans versely adjustable insai'd slots 2 Iii.4 The .external portion of the die bed 2N is provided with the transverse bolt holes 2-224 adapted.' to receive.v the transversely movable bolts` 224' having inner ends 2226 adapted to abut the external face 228 of the stationarydie block |94. Thus when itisdesired to. adjust the angle of tilt of the stationary die |31?, the adjusting bolts 22|!v are unloosened and the bolts 221|.V are. adjusted' transverseh7 relative tof each other to. tilt the entire die block t9# to end of the stationary die. -tilt has been Yattained-the bolts 220 are again tightened to clamp the stationarydie block |94 having Vpoints may be rolled if their blanks are initially 9 provide suicient space for insertion of the desired vsize screw blanks to be rolled at the inner When the desired to its bed 2 |4.

It is apparent however that any other suitable type of means for adjusting the oppositely inclined grooves |04 in the movable and stationary dies |30 and |32 respectively ,opposite each other such as by longitudinally sliding the dies |30 and |32 relatively to each other or otherwise may be employed and it is obvious that any suitable type of means for raising or adjustably tilting the face of one die relative to that of the other may also be alternatively employed. The stationary die |30 is also preferably of less height than its co- -operating groove 200 so as to provide the space below it for adjusting the stationary die |30 relative to the movable die |32.

As shown, the screws |0 are provided with the threads *i8 throughout a greater portion of their length, usually about two-thirds of their over-all length including the heads 'l2 for a nat headed screw.

I have described hitherto the rolling method and apparatus common to De Vellier Patent 2,314,391. As stated hitherto, my present invention relates to renements of said method and apparatus tol positively produce the right point in use and to successively in use produce identical right points.

In employing said invention in commercial practice, even with the same amount of excess metal on the pointed portions of the screw blanks, slight variations in the shape of the points in successive screws were produced. All matters of prior known shop practice were carefully checked, namely the circumference and dimensions of the blanks were measured, and the method of making the dies to the right theoretical dimensions and the method of setting the machine and dies to make the screws roll between the dies to make double threaded screws in accordance with the showing in my copending application for patent, Apparatus for rolling double threaded screws,

' s. N. 598,675, med June V11, 1945, carefully checked and still variations in the points of the screws occurred. It remained for the present inventor to further visualize the fact that in order to make a predetermined point and successively roll screws having substantially identical predetermined points, it was necessary to correctly register the pointed portion forming portions of the screw blanks'at the right height between the pointed ,portion forming portions of the die cavities by-supporting a blank at the right height at the initiation of forming threads on said blank and supporting' successive blanks as they are rolled on said dies at the same suitable right height at their respective initiations of forming threads on said blanks. It was only after suitable means were provided for this purpose and the thorough realization that this method was necessary that the present invention was evolved and screws having substantially identical pointed por- `tions successfully rolled successively. I discovered that once the threads are started right, if the blanks are of a correct circumference and other dimensions; the dies carefully made to correct theoretical measurements and the machine andv dies correctly and properly adjusted, screws substantially identical predetermined correctly aimed to be initially correctly grabbed at the right points or height and that the screws will roll at exactly the same height they are started at throughout the remainder of their parssage through the dies to successively provide the right threads andthe right points. I discovered that itY was rst necessary to make the blanks and dies right in accordance with prior shop practice as shown herein, second tol provide them with an adequate and proper adjustment as shown herein, and finally to aim or start the blanks at the rightv heightas shown and claimed in this application, and that screws having substantially identical points would be successively produced.

The blanks hitherto `described are passed between therelatively movabl-e dies |30 and |32 with the dies being relatively inclined forwardly from their front to rear ends to produce the spacings shown in Figs. 6-10. I'o insure that the pointed portion forming portions 39 of each blank are supported, lfrom below, at the right height between the pointed portion forming portions |40 of said cavities |34 on both dies at the initiation of forming threads on said blanks, namely While passing through the position as shown in Figs. 1 and 6, to properly register said blanks for the remainder of their passage between said dies when they are supported by said dies to successively form continuous double or other threads on their shanks adjacent said pointed portions and to successively axially displace and mold said excess metal on said pointed portions to form continuous threads on said pointed portions, terminating in substantially identical sharp incising means of the desired predetermined shape projecting substantially axially downwardly of said pointed portions, on diametrical portions thereof where double threads are rolled to successively produce screws having substantially identical predetermined pointed portions, for this purpose, I provide positive means to support said portions of said blanks opposite said portions of said dies during this period from below as shown in Figs. 1-12. The upper ends of the dies are provided with the filler plates |30f Yand |32f secured thereto by the screws |3l.

I support the blanks from below during this period of initiation of forming of the threads as shown in Figs. 1-12, and, as shown in said figures, for this purpose I employ a bottom stop 230 for abutting and supporting the lower ends of the blanks 98 between the dies |30 and |32 during the initiation of forming threads thereon. In order that quick variations or adjustments may be .made in the relative positions of the pointed portions 99 and |40, said bottom stop lis preferably vertically adjustable. While said bottom stop may be mounted between the dies |30 and |32 in any suitable manner, in my preferred embodiment l'. have shown it mounted at the front end of one of said dies, as shown, of the stationary die |30.

In the preferred embodiment shown, the front forward corner of the stationary die |30 is cut off to provide the oblique portion 232. A supplemental cavity 234 is also cut obliquely along the top of said portion. The central portion of the oblique portion 232 is provided with a truncated triangular channel 236 extending from the bottom thereof upwardly towards said cavity 234. A cooperating adjustable plug 238 of similar truncated triangular shape but ofv shorter height is vertically movable up and down within :assenso said channel :236. -=Said triangular pl-ug 238 'is lprovided with a ver-tical .threaded -hole 240 therein. A top plate 1-250 -of la height .slightly greater than .Said cavity 234 its said cavity and is secured to the portion of :the stationary -die below it by means of the screws :252. `Said plate 250 is provided with a central hole 254 to receive the adjusting screw 256 (therein, the threaded shank `258 of which projects downwardly through the threaded hole 240 `in the -triangular plug 238. It is obvious .that by turning the :adjusting screw 256 the vertical ,height of `the plug 238 in the vertical `channel .236 .maybe adjustably varied. The rear edge of the plate 250 from the rear edge of the .oblique wall 232 .rearwardainclines .downwardlyas at 25D to theller .plate flfior a purpose to Ybe Idescribed. The adjustable bottom stop 23B is obliquely bent .to have the portion 262 .overlie .the oblique wall `portieri e232 and the ,portion 254i overlie .the forward 4edge of the die and the front ,part .of the die cavity |3'4 .over the pointed .por-tion .forming portion MB, The ,portion 262 .of the bottom stop is provided with a central hole 26E to receive 'the screw 268 projecting within a horizontally threadedhole 210 'in the vertically adjustable ,plug 238. To prevent the bottom stop 23B 'from pivoting relative to the plug 2238, it is ,preferablysllpplementally pinned thereto by the pins 212.

To adjust the relative height of the upper edge 2M of the rearwardly projecting end 216 of the bottom stop 23! vertically relative to the pointed .forming portion 'ADjit is lobvious that it is merely necessary to turn the adjusting screw 25S registering in the 'hole '24B in the plug '238 to 'relatively 'raise and lower .said edge 214 through the medium of .raising vand lowering lthevplug 238 mounting said bottom Astop 23D. As the heads "I2 of the blanks 98 are feiiLin between the 'dies it is apparent that they are irs't `supported by the upper surface of the top plate 250 as their lower ends B9 .abut Vthe upper edge '214 of the bottom stop'23 -but that asthe inclined plane 260 lowers away from the heads I2 the lower ends -99 are supported solely by the upper edge 214 4of the i bottom stop 23B as the pointed portion forming portions o9 'of the screw blanks 98 approach `and contact the pointed portion forming portions Hl] of the dies. It is apparent however thatany other `suitable 'type of a `verl'iical'ly adjustable bottom .f

stop, may be employed in place of the bottom stop shown.

As stated, Imay'vary the shape, width, depth, included and pitch angles of the groove means in accordance with the type or size Iof screw desired Vto be rolled.

It vis apparent, '-however, that by using my improved apparatus I 'amenabl'ed to provide a predetermined point and successively reproduce the same point, particularly eon double threaded screws of -the vtype shown in said De Vellier Patent 2,314,391, with ithelother advantages described above.

It is understood that my invention is notlimited tothe specific embodiments shown and thai'l varifous deviations thereof may be made without departing from `thesp'irit and scope `of the appended claims.

What I claim is:

`1. Apparatus for successively rolling substan- 'tially identically pointed double threaded screws, comprising a pair of relatively movable rectilinear screw thread rolling dies capable of v'only rolling 'double threads, each havin-g a face comprising fa continuous cavity extending longitudinally thereof., having a cooperating inwardly tapered portion at the upper edge thereof, a :substantially iiat central lshank forming portion :and a lowerV screw point forming portion "tapering `outwardly to the ysurface of said ifa-ce beyond said .cavity, a plurality of similar continuous thread torxning grooves extending iobliquely thereof at a pitch angle of :from .substantially 12 to .substantially 22 :and extending throughout the height ofisaid -face through said shank and :screw point 1form-ing portions, of .substantially equal depth in said shank forming portions and sof progressively decreasing ldepth 1in said )screw point forming portions `along the fax-is =o a screw blank interposed transversely 'between said dies, `of progressively decreasing depth .and wid-th at least Ialong the major portion of the length 'thereof and with successive grooves of progressively decreasing relative depth and 'width throughout at least the major portion of the length ofsad-cavi'ty forming lands between the grooves that lprogressively widen throughout at least the major portion thereof, means -ior mounting 1said 'di-es -so that their entire faces remain at va spaced distance from each other and inclined relatively forwardly from their front to rea-r ends with their 'groove means oppositely inclined to roll 'double screw threads on screw blanks having Shanks Iand screw point formingportions hav-'ing an excess of metal greater than `required for corlically pointed portions, rolled lbetween them with the 'lower ends thereof initially spaced from the lower lends 'of Ythe cavities and with similar portions of similar Agroove means in each die continuously opposite similar 'portions of respective oppos'iteIy 'inclined groove means in the opposite die along the re- 'spective successive `'lines o'f contact of 'said dies with said screw blanks and a vertically adjustable bottom `stop of limited "length `at the extreme starting end of one die only for initially labutting and Ysupporting the lower ends of said 'blanks 'between said dies so that 'the screw point forming portions of successive blanks are .at the same suitable height between the screw point forming portions of said die .cavities 'at 4lthe initiation `of form- .ing 'threads on said blanks, 'to provide `the same amount of material on .said blanks moldab'le and axially displaceableto successivelyfproduce screws having substantially identical ,predetermined screw points.

2. .Apparatus for successively rolling substantially identically pointed double threaded screws, comprisinga pair o'f relatively movable rectilinear screw thread rolling dies capable of only rolling double threads, each 'having .a face comprising a continuous 1cavity extending longitudinally thereof having a substantially .hat central sha-nkorming portion and a lower screw point forming ,-portion tapering outwardly kto fthe surace of said .face beyond said cavity, having a plurality of similar continuous thread .forming grooves .extending obliquely `thereof atapi'tch angle of from substantially .132 to substantially 22 and kextending throughout the height of said face through said shank and screw :point form-ing portions, of substantially equal .depth in said yshank form-ing portions andiof progressively decreasing depth in Said screw point formi-ng portions along the axis of a `screw blank interposed 'transversely between said dies, of progressively ldecreasing depth and Width -at least along the major portion of the length thereof and -with `successive grooves of progressively decreasing relative depth and width .throughout :at :least the maior portion "of the l 3 length of said cavity forming lands between the grooves that progressively widen throughout at least the major portion thereof, means for mounting said dies so that their entire faces remain at a spaced distance from each other and inclined relatively forwardly from their front to rear ends with their groove means oppositely inclined to roll double screw threads on screw blanks having shanks and screw point forming portions having an excess of metal greater than required for conically pointed portions, rolled between them with the lower ends thereof initially spaced from the lower ends of the cavities and with similar portions of similar groove means in each die continuously opposite similar portions of respective oppositely inclined groove means in the opposite die along the respective successive lines of contact of said dies with said screw blanks and a vertically adjustable bottom stop of limited length at the extreme starting end of one die only for initially abutting and supporting the lower ends of said blanks between said .dies so 14 that the screw point forming portions of successive blanks are at the same suitable height between the screw point forming portions of said die cavities at the initiation of forming threads on REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,734,752 Thomas Nov. 5, 1929 1,912,879 Arenz June 6, 1933 20 1,972,225 Hogue Sept. 4, 1934 2,314,391 De Vellier Mar. 23, 1943

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