US2968201A - Two roll, cylindrical die machine for thread rolling - Google Patents

Description

Jan. 17, 1961 A. B. REED ET AL TWO ROLL, CYLINDRICAL DIE MACHINE FOR THREAD ROLLING Filed March 51, 1954 H 3 Sheets-Sheet 1 A.Bradforcl Reed.

Georqe U L-q w' llllllHl Jan. 17, 1961 A. B. REED ET AL TWO ROLL, CYLINDRICAL DIE MACHI iNE FDR THREAD ROLLING Filed March 31, 1954 3 Sheets-Sheet 2 mm m I. .d w "me am mw AG Jan. 17, 1961 r A. B. REED ETAI. 2,968,201

TWO ROLL, CYLINDRICAL DIE MACHINE FOR THREAD ROLLING Filed March 31, 1954 3 Sheets-Sheet 3 [Hill C2611; :QLTT E Y Unite States Patent TWO ROLL, CYLINDRICAL DIE MACHINE FOR THREAD ROLLING Arthur Bradford Reed and George W. Lyman, Holden, Mass., assignors to Reed Rolled Thread Die Company, Holden, Mass, a corporation of Massachusetts Filed Mar. 31, 1954, Ser. No. 420,068

6 Claims. (CI. 80-6) three rotated dies arranged to be moved radially inwardly through fixed distances to roll a thread on the workpiece therebetween. In such a three roll machine, the minimum size of the work that can be rolled is limited by the work space between the rolls when they are located just out of contact; whereas, two die rolls are capable of rolling a very small workpiece arranged substantially diametrically therebetween. Various proposals have been made heretofore for using two die rolls to roll a thread on a work piece. In one type of machine, the work is fed to the rolling zone by means of a notch in an upper roll, and it is removed by a notch in the lower roll. There are, however, certain limitations in the use and operation of such machines, due to the requirement of avoiding interference between the incoming and outgoing work pieces and with the consequent waste of useful thread rolling contour of the die. Furthermore, a two roll machine requires a steadyrest to hold the work between the die rolls against the thread rolling thrust, but the work grows in diameter as the thread is formed, and this serves to move the axial position of the work and interfere with a proper rolling operation. Also, the newly formed threads may stick to the die roll and interfere with removal of the work piece.

The primary object of this invention is to provide an automatically operated machine in which two die rolls are so shaped and arranged that work may be fed automatically to and discharged from the rolling zone by means of work carrying grooves or notches in one of the die rolls which insure a positive feeding and removal of the work.

Another object is to provide a machine of this class in which the work is fed to and removed from the thread rolling zone by means of a single thread rolling die which is so shaped that a work piece may be fed to the operating zone immediately after a finished piece is removed therefrom and without interference therebetween.

Another object is to insure a positive removal of a finished work piece without interfering with the ingress of an unworked blank- A still further object is to provide an automatically operated mechanism which will support the work during the rolling operation and permit diametrical expansion thereof while maintaining the work axis substantially in a fixed position relative to the die rolls, so that the work is held steady in a proper rolling position.

Another object is to provide a construction comprising a retreating work rest which maintains the work axis properly positioned and substantially stationary for the thread rolling operation and which will cause the work to roll out of its operating position and be discharged satisfactorily from the machine.

A further object is to provide a machine of this type which will roll threads on odd shaped work pieces, such as 2,968,201 Patented Jan. 17, 1961 those having large heads which are not readily supported in or fed to a standard type of machine, and to feed such pieces to and remove them from the work zone and to provide a high production rate for rolling articles of similar shapes and characteristics.

Further objects will be apparent in the following disclosure.

A machine made in accordance with this invention comprises two die rolls, only one of which has notches or grooves in its periphery so arranged that one. notch will receive a finished work piece and remove it from the operating zone, while a second notch located close to and following the first will positively introduce a new work piece to the zone for another thread rolling step. The other die roll has an unnotched or uninterrupted thread rolling periphery. The die rolls are preferably arranged on fixed axes except for adjustments that may be required for rolling work pieces of different diameters. The roll axes may be arranged in a horizontal, vertical or obliquely positioned plane. The progressive rolling of a die thread into the work is accomplished by providing one or both of the dies, and preferably only the notched roll, with a partial substantially spiral contour, as determined by the thread arrangement thereon, which is so arranged relative to the in-feeding work notch that once the work piece has been introduced into position, the lowest or shortest radius portion of that spiral die shape will initially engage the work and the die threads of the two rolls will gradually penetrate the work periphery as the spiral contour re-' volves. A work support serves to hold the work in a proper position and preferably just slightly off a center line connecting the die roll axes so as to prevent the work from being thrown outwardly off the rest. Since the work piece expands in diameter by about the depth of the finished thread, the work rest is progressively moved away from the work axis at a rate which insures that as the work grows in diameter its axis will be held substantially stationary. The work is fed from a magazine into the loading notch by a timed device which insures that the unloading notch remains free. At the end of the work rolling operation when the work remoxing notch comes into position, the work is urged into that notch for removal from the rolling zone by means of a camming surface, such as a positively operated ejector or an inclined surface so arranged that the work may roll down it into the notch. To facilitate such work removal, the work rest may be moved temporarily from its operating position far enough to permit the work to enter the notch readily. If the work ejection is to be effected positively, this may be done by a cam operated camming plunger entering the work zone from the side opposite to the work rest and which is timed to forcibly move the work piece into the discharge notch at the time when the notch is opposite the work piece on the work rest.

Provision is also made in a two die roll machine for adjustably tilting the dies separately. This is accomplished in one construction by mounting a support for each die roll on a pivot body which provides for swinging the die axis in a common plane with the work axis to adjust for taper, and wherein the pivot body is in turn adjustable about an axis perpendicular to its own axis so as to tilt the die roll axes oppositely in parallel planes for thread matching. The die roll support and pivot body may also be fixed as a unit and moved laterally to adjust for work size. Such a machine may, if desired and preferably, em? body any of the above described work feeding and removing features.

Referring to the drawings:

Fig. 1 is a somewhat diagrammatic fragmentary elevation of a machine having both a cam moved work rest and a cam operated work ejector, which shows a piece of,

work being rolled and another being delivered to the feeding notch;

Fig. 2 is a similar view showing the positions of the parts, during ejection of the work;

Fig. 3 is an elevation taken at right angles to Fig. 2;

Fig. 4 is a diagrammatic fragmentary enlarged end view, of the die rollsillustrating the work feeding stages;

Fig. 5 is a diagrammatic view of the drive mechanism for the die rolls and cams;

Fig. 6 is a diagrammatic elevation of a modification in which the positive work ejector of Fig. l is replaced by a stationary inclined plane which serves as the work removing cam, which shows a steadyrest in a work supporting position and two work pieces in the loading and rolling positions respectively;

Fig. 7 is a similar view showing the steadyrest in a lowermost position and the rolled work piece delivered tothe discharge notch;

Fig. 8 is atop plan detail of the die rolls showing the relation. of the dies to a work piece and the work ejecting support of Fig. l; and

Fig. 9 is a fragmentary top plan view of one die roll, the work and an inclined camming ejector for the work shown in Fig. 6.

The thread rolling machine shown in Figs. 1 to 6 inclusive comprises two die rolls 10 and 11 suitably mounted on driven arbors for rolling a work piece W therebetween. The arbors of the die rolls It] and 11 may be arranged in parallelism in either a vertical or a horizontal plane. If the thread 12 on each roll (Fig. 8) is; a helix of required configuration, the roll axes are parallel, but if the die threads are annular and parallel, then the axes of the die rolls will be tilted at suitable angles. Also, the number of starts of the helical threads on each die roll is about equal to the ratio of the diameters of the die roll and the work. Various other theoretical considerations understood in the industry are involved in the construction of such a machine, in order to obtain the desired thread structure. In this two roll machine, the arbors are located with their axes stationary during the work rolling operation and they are movable only for required adjustments to provide for differences in work size, taper and type of thread or fin to be rolled. The thread rolling operation is preferably accomplished by having the contour of one or both of the die rolls shaped substantially on a spiral.

In the preferred embodiment illustrated, the roll 11 has asuitable helical type of thread formed on a true cylindrical surface, and the helical threads on the roll 10 are provided on a die roll surface which is shaped somewhat like a spiral cam. As the rolls revolve, successively higher portions of the threads of the spiral body are forced into the work piece and cause the correspondingly shaped threads to be formed thereon. As indicated diagrammatically by the dotted line contour of the die roll 10 in Fig. 4, and by the phantom showing of the work on the work rest, the low portion 14 of the die thread first engages the work and the work thread is formed as the increasingly higher portion of the die thread is thrust into the work. The spiral shape of the die roll 10 terminates at a given distance from the starting point 14, such as at the point 15 near the bottom of Fig. 4. which is about 180 from the feeding notch, and the surface 16 of the roll from that point 15 to the discharge notch is substantially cylindrical, except for the helical threads thereon. Thus, in this particular roll shape of Fig. 4, the work is rolled through a distance of approximately one half of the periphery of the die roll where the thread increases in its radial height from the die roll axis, and then the portion 16 of the die roll thread formed on a cylindrical portion of the roll serves to true the previously rolled thread and smooth out irregularities that may have developed in the rapid flow movement of the work material during the stage of thread rolling on the spirally shaped roll surface.

A primary feature of this invention comprises a construction which provides for automatically feeding a work piece to the thread rolling zone and removing a previously rolled piece therefrom. This is accomplished by means of grooves or notches 20 and 22 on the one die roll 10. The notch 20 in this die roll is for the purpose of introducing the work to the rolling zone. The other notch 22 which is spaced from and precedes the notch 20 in the revolution of the work in the direction of the arrow (Fig.4) serves for removing or discharging the work after it has been rolled. The notches are closely juxtaposed to avoid wasting peripheral space on the roll, and the notch spacing (Fig. 4) is preferably such that the work removal notch can get the work away from the work rest just prior to the delivery of a new piece thereto. The work W is supported in the rolling zone by means of a work rest 25 which is located to hold the work in a correct position between the die rolls and preferably slightly below a horizontal center line connecting the axes of the two rolls, so that the work is held just below the narrowest portion of the throat between thedierolls and so cannot be lifted outwardly from the operating zone.

Another feature of this construction comprises mechanism which progressively moves the work rest 25 away from the work axis during the thread rolling operation at a predetermined rate which maintains the axis of the work substantially stationary. That is, the work grows in radius by substantially one half of the depth of the finished work thread as the die threads penetrate the work piece and cause its metal to flow outwardly into the-parallel or helical grooves of the die rolls. Hence, the work rest 25 (Fig. 1) is mounted to be moved at a predetermined rate. and through a fixed distance by a lower cam 30 which is rotated in timed relationship with the dieroll rotation. While the spiral surface 14 (Fig. 4) of the die roll 10 isbeing impressed into the work and the work is expanding in its outside diameter, the work rest 25 (Fig. 1) is moved downwardly in the machine illustrated by means of a spiral surface portion 31 of the cam 30. The radius of this surface 31 decreases at'a predetermined rate for a desired distance, such as from a high starting point 32 or through an angular distance corresponding with the angle subtended by the spiral threaded surface 14 (Fig. 4) of the die roll. A second portion 33 of the cam is substantially cylindrical, so that after the thread has been rolled to the required depth and the diameter of the work has reached its maximum, then the work rest 25 is held stationary during the final finishing operation in which the threaded cylindrical portion 16 (Fig. 4) of the die roll is operating to smooth up and finish the work thread. The notched die roll may havemore than one pair of feed and exit notches, so that a plurality of pieces may be rolled for one revolution of the. die; and the constructions of the cams are duplicated accordingly, or the cams are rotated at a higher speed and in a predetermined relationship to the die rotation.

A suitable construction for this steadyrest or work rest comprises a stationary sleeve 34 suitably mounted on the machine frame, within which slides a cylindrical mount 35 carrying the steadyrest 25 thereon. This steadyrest mount carries a suitably shaped body 36 tapering upwardly into the narrowing space between the die rolls 10 and 11, and it isso shaped that the work will be adequately supported in the rolling zone but will be permitted to escape therefrom when ejected into the discharge notch 22; The slidable body 35 has a flange 37 at its bottom portion, and a helical compression spring 38 engaging a shoulder of the sleeve 34 and the flange 37 serves to hold the steadyrest in a lowermost position. A bifurcated yoke member 39 fixed to the under side of the flanged portion 37 carries a cylindrical cam roller 40 which rides on the peripheralsurface of the cam 30 and thus, with the aid of the spring 38, causes the steadyrest to move progressively downwardly at an exact rate controlled by the cam shape which corresponds with the rate of diameter growth of the work so that the work axis remains stationary during the rolling stage.

- The work is fed to the rolling zone by means of the slot 20 in the die which is of a shape and size (Figs. 1 and4) adapted for receiving a work piece 44 from the magazine 45 shown simply in the drawing as a vertical hopper tube carrying a set of work pieces 44 in vertical arrangement between the parallel walls of the hopper. A curved arm 46 forming a continuation of one of the hopper walls is so shaped and mounted in a concentric relation to the roll 10 that the lowermost work piece 44 delivered from the hopper may slide around heneath and substantially in contact with that arcuate wall 46 and be held thereby in the feeding notch 20 as it progresses towards the steadyrest. As indicated in Fig. 4 by the dotted lines at the right adjacent to the steady rest 25, the notch 20 is so shaped as to provide a cam surface 48 at its upper portion which serves, when the work strikes the rest 25, to force the work to leave the notch 20 and to ride over onto the steadyrest 25 into a work rolling position. The steadyrest projects closely enough to the work carrying roll 10 so that there is no space for the work to pass downwardly with the roll, and that camming surface 48 of necessity causes the work to roll laterally over the steadyrest and into a rolling engagement with the other roll 11. The upper portion of this carnming surface is shaped to merge with the substantially spiral shaped portion 14 of the cylindrical die 10 A suitable feeding device has been provided so that the work pieces 44 may not be delivered to the discharge notch 22 which precedes the feeding notch 20 in its path of travel. This may comprise a horizontally slidable gate 50 (Fig. 1) having its lower face bevelled to form a sharp front edge which is adapted to be thrust between the work piece admitted to the notch 20 and the one immediately thereabove in the hopper 45. This gate, which is slidably mounted on a suitable support, is held in a forward work supporting position by means of a compression coiled spring 53 suitably mounted at the rear of the gate. The gate, which normally closes the bottom of the hopper or supports the column of work pieces thereabove, may be retracted momentarily to allow a single work piece to drop into the slot 20 by means of a bell crank lever 55 having one end slidably riding against the surface of a vertical lug 56 fastened to the gate. This lever is suitably pivoted on the framework of the machine at 57, and its upper end carries a roller or cam follower 58 arranged to ride on the peripheral surface and to be moved by a rise 59 on a positively rotated cylindrical cam 60. This cam is timed to make one revolution for each revolution of the die roll 10, and the raised portion or bump 59 has a suitable radial height and isso located that a work piece 44 is released into the notch 20 just as the latter comes into position beneath the hopper. Thereafter the gate is quickly returned into position between the work piece in the notch and the other pieces thereabove.

It will now be appreciated that after a work piece W has been delivered to the steadyrest 25 and the latter is being gradually and progressively withdrawn to allow for the growth in diameter of the work, and after the steadyrest movement has stopped and the threads on the cylindrical die roll 11 and the cylindrical portion 16 (Fig. 4) of the die roll 10 have accomplished their purpose of cleaning up the threads, then by that time the discharge notch 22 has reached a position opposite the work, as shown in Fig. 2, so that the work may be discharged into that notch and removed from the operating zone. An arcuate plate 62 is mounted beneath the die roll 10, and it is so shaped that the finished work piece which has entered the slot 22 may be moved downwardlyand rolled along that plate until it reaches an arranged to deliver the work pieces as desired.

One construction which will serve to cam the finished work piece W into the slot 22 is illustrated in Figs. 1 to 3. This comprises a vertically reciprocable ejector arm 65 mounted on the lower end of a cylindrical body 66' slidably riding within the sleeve 67 fixed on the machine frame. The body 66 'has a flange 68 at its upper portion which is urged upwardly by a surrounding helical compression spring 69 located between that flange and the top of the sleeve 67. This serves to hold the ejector carnming prong 65 normally away from the work piece. The positively rotated camshaft 70 (Fig. l), which carries the gate moving cam 59, has a further cylindrical cam 72 fixed thereon. This cam has an abrupt rise 73 so located that as the cam 72 revolves it will strike a roller 74 mounted in a yoke 75 on the upper end of the slidable body 66. When that raised portion 73 of the cam strikes the roller, the ejector prong 65 is forced downwardly with a sudden motion and then immediately withdrawn by the spring 69. This downward motion of the ejector 65 takes place just as the slot 22 comes around to a position opposite the steadyrest 25 and is ready to receive the work piece, as is shown in Fig. 2.

In order to aid the work discharging acti0n,,it is preferred to move the steadyrest out of the way in the narrow space between the two die rolls. That is, the rest is moved abruptly downwardly in timed relation with the ejection of the work piece into the notch 22 and so enlarges the work discharging space. This is accomplished by a deep notch 78 in the lower cam 30 which is so located and shaped that the roller 40 may drop into the notch and allow the rest to retreat sufiiciently far so that the work may readily pass its front edge facing the die roll 10 and fall onto the curved plate 62 and be carried away from the forming zone. As soon as the work has passed the forward edge of the steadyrest, the latter is moved back into a work receiving position and in time to receive a new piece of work which will be cainrned onto its surface by the carnming portion 48 of the notch 20.

Suitable structure serves to support the rolls and a suitable driving mechanism is employed to drive these various rolls and cam members in a correct timed relationship. As illustrated diagrammatically in Fig. 5, this may comprise a constant speed electric motor 80 of desired char- 7 acteristics which is mounted in the machine base and belted to a drive pulley 81 fixed on a main shaft which carries a gear 82 meshing with a gear 83 keyed on a parallel shaft which has a further gear 84 arranged to drive a pair of meshed change speed gears 85 and 86 which serve to vary the speed relationship. The change speed gear 86 is connected through universal joints to drive the shaft of one die roll. A gear 87 fixed on that die roll shaft drives through an intermediate idler gear 88 a gear 89 connected through a universal joint to drive the other die roll shaft, such as is shown in Fig. 12. The intermediate gear 88 also meshes with the gear 90 fixed on the shaft of the lower cam 30. The upper cam members 60 and 72 are driven by the die roll drive 87 through an intermediate idler gear 92 meshing with gear 93 on the cam shaft. These various parts have such gear teeth combinations and arrangements that the cams are driven in an exact timed relation with and through one revolution for each rotation of the work carrying die roll 10, so as to satisfy the above described functions of the machine.

A simplified form of machine is shown diagrammatically in Figs. 6, 7 and 9. In this construction, the mechanism is the same as above described except that the movable ejector 65 and associated cam operating parts have been omitted. ejector 95 has been arranged at the right hand side of the work piece W or opposite the roll 10. This ejector is an inclined plate suitably mounted on the framework to provide a surface down which the work may be cammed.

In place thereof, a stationary carnming It.is,preferably arranged as a slotted or bifurcated.

member having a recessed portion (Fig. 9) within which the upper end of the steadyrest 25 may project and slidably move. This inclined surface is normally remote from the work during the rolling operation. When the steadyrest 25 is moved downwardly by the cam roller 40 dropping into the slot 78, the work falls down against the two spaced arms of this stationary inclined camming surface of the ejector, and that inclined surface causes the work to roll down its face and into contact with the wall 62 from which the work escapes into the pocket 63. It will thus be appreciated that this inclined surface serves as a cam which, in cooperation with the movable steadyrest 25, causes the work to be ejected into the slot 22 and so to be removed from the machine. Other features of the mechanism, as described herein, may be incorporated in the machine so as to provide a complete and operative but simplified construction.

As to the operation of the construction shown particularly in Figs. 1 to 4, the work pieces 44 are fed serially from a hopper 45 into the axially parallel work feeding groove 20 of the die roll 10 while other work pieces are held back by means of the spring pressed cam operated gate or plunger 50. This gate is moved periodically by means of the positively rotated cam 59 and in timed relation with the die roll movement, so as to present a work piece to the notch only when the latter is positioned to receive it. That work piece is carried around from the position of Fig. 1 to the position shown in dotted lines at the right of Fig. 4, where the camming surface 48 of the notch 20 moves the work piece over onto the steadyrest 25. The die rolls rotate in the directions of the arrows of Figs. 1 and 4 and thus the spiral portion 14 of the die thread surface is progressively thrust by a plunge type of operation directly into the work to form the thread thereon. This thread forming operation takes place through a rotation of about 180 of the die roll 10 or to a point where the spiral body portion 14 to 15 of the die roll merges into the threaded cylindrical die roll portion 16, whereupon the work thread that has been formed is smoothed and trued. The other die roll 11, which prefer ably has a cylindrical shaped body on which the threads are superimposed, cooperates with the roll 10 because of their synchronous rotation provided by the driving mechanism. The die roll 11, whether spiral or cylindrical in its. fundamental shape, has its thread structure uninterrupted by work carrying notches, so that its thread rolling operation is substantially continuous. These rolls will, of course, have been previously adjusted rotatably or otherwise to provide the necessary thread matching.

In due time, the work discharge or removal notch 22, which is longitudinally parallel with and travels ahead of the work feeding notch, reaches a position opposIte the steadyrest, whereupon the work rolls into that notch and is removed from the rolling zone. In order to aid the discharge of the work into the notch, the steadyrest may have its work supporting surface slope towards the die roll 19 to serve as a camming surface which will cause the work to roll down into the notch. The shape of the notch 22 is such that by the time the upper substantially radial shoulder of the notch reaches the work, the work is entirely off the steadyrest and will be carried around the guard or track 62 to a discharge point. It is preferred that the steadyrest be level and that the work be cammed positively into the notch, and to this end a. reciprocating and camming ejector 65 may be employed. This ejector is moved in timed relation with the presentation of the notch 22 to the work on the steadyrest and serves to thrust the work piece into the notch and insure its positive removal from the rolling zone, as is particularly indicated in Fig. 2.

In the modification shown in Figs. 6 and 7, a camming shelf 95 is employed in association with a movable steadyrest, to insure discharge of the work. In this case, the steadyrest is moved downwardly by the spring 38 when 8 permit ed by g o ve 78 in h am..30,w ih.re-. volves intimed relation with the movement of the notch 22 into a work receiving position. That is, the steady rest drops out of the way and the work then rests on the inclined surface and thus is rolled into the notch 22.

The thread rolling operation is one of displacing metal, and the work therefore grows in diameter. In order to maintain the axis of the work substantially stationary during the thread rolling operation, the stea dyrest 25 is caused to retreat at a rate substantially equal to that of the radial work growth, so that the axis remains sta; tionary. This is effected by means of the spiral cam surface 31 on the cam 30 which supports the steadyrest and" travels at the same angular rate as does the die roll, so that the decreasing radius of surface 31 causes the steadyrest to remain in its work supporting position and hold the axis of the work substantially stationary,

It will be appreciated that various modifications may be made within the scope of this invention and that the;

constructional details of the machine may follow the standard or other practices of those skilled in the art.

For example, if the plane of the die roll axes is vertical or positioned at any other angle to the horizontal .in-

dicated in the drawings, the various parts and operation of the machine will be modified accordingly. However, the essential principles of the machine will not be af-' fected. The term thread is used herein to define either a helical or continuous thread, whether a ridge or a inwardly into a short work piece which is no longer than the axial width of a die roll; but for longer work pieces the die rolls may be so tilted or the threads so shaped that the die roll threads penetrate the work piece initially to a maximum depth and the work thread is formed progressively as the work piece is moved axially. The plunge type of rolling requires either the substanf tially spiral die body shape of Fig. 4 or a progressive in-feed of a cylindrical die roll towards the workaxis. The axial work travel requires that the die be either cylindrical or tapered and without notches'for axially prd gressive work rolling. It will be appreciated that different types of rolling machines may embo'dyvarious fea tures of the above described invention, and will befmodified accordingly.

Hence, the above disclosure is to be interpreted as setting forth preferred embodiments of the invention and not as imposing limitations on theappended claims.

1. A thread rolling machine comprising two rotatable die rolls having matched threads for rolling a work piece therebetween, means for mounting the rolls on fixed axes in peripheral opposition during the 'rollingoperation, a work rest forremovably supporting thework in the thread rolling zone, driving mechanism for rotating the rolls in synchronism and continuously in the same peripheral direction and rolling the work thread, one rollonly being peripherally recessed and providing a feeding'notch station shaped and arranged for receiving a work piece and transporting it to the rest and a discharge" notch station closely in advance of the other for subsequently receiving the finished work and removing it from the rolling zone, the other roll having a substantially uninterrupted periphery provided with work rolling threads, means operating in timed relation with said rolls which provides for the delivery of work pieces in sequence to the work receiving notch station when the receiving notch is positioned therefor, said work feeding and work discharging stations being in an axially parallel closely juxtaposed arrangement but separated sufliciently to insure discharge of a work piece from the rest immediately prior to a new piece being fed thereto, the remainder and major portion of the recessed roll periphery having a work rolling thread thereon and means for moving the work rest away from its initial work supporting position in a timed relation with the die roll rotation.

2. A thread rolling machine comprising two opposed rotatable die rolls having matched threads for rolling a work piece therebetween, means for rotating the die rolls in synchronism and continuously in the same peripheral direction, a work rest for removably supporting a work piece between the die rolls, one only of the die rolls being peripherally notched to provide juxtaposed, axially parallel work feeding and work discharging stations, the work discharging station closely preceding the other in the direction of rotation, the notched die roll having a substantially spiral body portion adjacent the feeding station provided with a work rolling thread merging with a threaded portion adjacent the discharging notch which is concentric with the roll axis, said threads extending substantially throughout the major distance between the stations, the other roll having a substantially uninterrupted thread rolling periphery concentric with the roll axis, the notch at said work feeding station being shaped to deliver a work piece to the work rest when opposed thereto, said spiral thread portion serving to force the die roll threads into the work, means for rotatively supporting the rolls with their axes stationary during a rolling operation, means for feeding work pieces serially into the work feeding station in timed relation with the die rotation, and means including a camming device for causing removal of a finished work piece from the work rest into the work discharging notch station when the latter is moved into opposition to the work on the rest.

3. A thread rolling machine comprising two opposed rotatable die rolls having matched threads for rolling a work piece therebetween, supports for holding the die roll axes stationary during the work rolling operation, means for rotating the rolls in synchronism and continuously in the same peripheral direction, one roll only having a notched periphery providing separate closely juxtaposed work feeding and work discharging notch stations, the other roll having an uninterrupted thread rolling periphery, means operating in timed relation with the notched roll rotation for delivering work pieces successively only to the work feeding notch station as the latter is presented therefor, a work rest for holding a work piece 10 between the rolls for a thread rolling operation, and means operating in timed relation with the notched roll rotation for moving the work rest radially of the work and gradually at the rate of increase of work diameter and holding the work axis stationary during the rolling operation.

4. A thread rolling machine according to claim 3 in which the work rest movement is effected by a mechanism including a cam moved in timed relation with the notched roll rotation and so shaped that the rest is lowered during the work rolling operation at the rate of the increase of work radius and thereafter removed to a remote position which permits the work to be discharged into the work receiving notch station.

5. A machine according to claim 3 in which the camming device comprises a reciprocable ejector and mech anism operating in timed relation with the die roll rotation which serves to move the ejector and remove the work from the steadyrest into the work removal notch.

6. A thread rolling machine according to claim 2 in which the camming device has a surface portion located beneath the work and inclined downwardly towards the discharge notch when the later is in a work receiving position, and wherein the work rest is so located relative to said incline that its downward removal causes the work to contact and roll down the incline into the discharge notch.

References Cited in the file of this patent UNITED STATES PATENTS 672,516 Schinneller Apr. 23, 1901 1,130,226 Warwick Mar. 2, 1915 1,370,978 Long Mar. 8, 1921 1,465,208 Canda Aug. 14, 1923 1,850,054 Strickland et al Mar. 15, 1932 1,946,735 Frayer Feb. 13, 1934 2,091,655 Scrivener Aug. 31, 1937 2,427,283 Hopkins et a1. Sept. 9, 1947 40 2,632,345 Hopkins Mar. 24, 1953 2,737,833 Plagemann Mar. 13, 1956 FOREIGN PATENTS 584,111 Great Britain Ian. 7, 1947 619,821 Germany Oct. 7, 1935 751,904 Germany Mar. 1, 1954 OTHER REFERENCES Reed Cylindrical Die Thread Rolling Machine, Machine Bulletin No. B -1,4 pages, Sept. 26, 1955.

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