US2632345A

US2632345A - Apparatus for forming rods, bolts, or the like

Info

Publication number: US2632345A
Application number: US641575A
Authority: US
Inventors: Cecil W Hopkins
Original assignee: Landis Machine Co
Current assignee: Landis Machine Co
Priority date: 1946-01-16
Filing date: 1946-01-16
Publication date: 1953-03-24
Anticipated expiration: 1970-03-24

Description

March 24, 1953 c. w. HOPKINS 2,632,345

APPARATUS FOR FORMING RODS, BOLTS OR THE LIKE Filed Jan. 16, 1946 4 Sheets-Sheet 1 v iii- CECIL w. HOPKINS March 24, 1953 c. w. HOPKINS 2,632,345

APPARATUS FOR FORMING RODS, BOLTS OR THE LIKE Filed Jan. 16, 1946 4 Sheets-Sheet 2 March 24, 1953 c. w. HOPKINS 2,632,345

APPARATUS FOR FORMING RODS, BOLTS OR THE LIKE Filed Jan. 16, 1946 4 Sheets-Sheet 5 c. w. HOPKINS March 24, 1953 APPARATUS FOR FORMING RODS, BOLTS OR THE LIKE Filed Jan. 16, 1946 .4 Sheets-Sheet 4 \ku. v

CE CIL' W. HOPKINS a discharge station.

Patented Mar. 24, 1953 APPARATUS FOR FORMING RODS, BOLTS,. OR THE LIKE Cecil W. Hopkins, Waynesboro, Pa., assignor to Landis Machine Company, Waynesbormla a corporation of Pennsylvania Application January 16, 1946, serial'No. 641,575

I 7 Claims. 1

This invention relates to an improved method and apparatus for forming rods, bolts or the like and contemplates the rapid quantity production "of such articles, with one or more parts thereof having an accurate predetermined structural configuration. While the machine or apparatus has certain of the general characteristics of a centerless grinding machine, in the operation of "the present invention, the desired form is not produceduponthework b a k by a srindirig a tion but by the displacement of the metal stock of thework blank under pressure contact of peripheral forming meansprovided on opposed rollingor rotating die members.

Itis one of the principal objects of my invention to provide a novel method of producing the desired form on the work blank which comprises rotating the die members in the same direction in pressure forming contact with the blank and progressively and equally displacing the metal in the relative rotation of said die members and blank during a portion of the revolution of said members, with a following forming operation upon the displaced metal in the continued revolution of the die members. This method has been found particularly desirable for accurately forming a clean screw thread on the work blank having the required helix angle and pitch diameter.

Another object of the invention is to provide a method of machine rolling the desired form in the work blank between rotating pressure dies in i which the work. blank is transferred from a work receiving station through a circumferential path path between the other of said members and the machine frame from they work forming station to A'further object of the invention is to provide each revolution of the die members. Thus a desirable economy is realized and the additional time, labor and expense involved in forming each thread on the work piece in a separate machine operation is obviated.

A more particularobiect of the invention resides in the provision'of the forming dies with work receiving pockets or notches so that the threading dies will also function as transfer -members for transferring a vwork blank from a 2 7 receiving station to a work forming station and from the work formingstation to the discharge station respectively. Thus the relatively complicated transfer mechanisms found informer machines of this kind are eliminated, greatly simplifying the machine construction and reducing maintenance expense to a minimum.

It is also an additional object of the invention to provide simple and easily adjustable means for correcting the position of'the work blank between the thread rolling dies" to produce a tapered or non-tapered thread thereon.

The invention further comprehends the provision of simply constructed and positively operatedf means for singly delivering Workblanks from a magazine at the work receiving station of themachine and also for removing or displacing the finished work piece from the thread rolling station. With the above and other subordinate objects in view, the invention comprises the method and apparatus for forming rods, bolts and thelike, as will hereinafter be more fully described, illustrated in the accompanying drawings and subsequently incorporated in the subjoined claims."

In the drawings, 3 wherein I have illustrated several simple and practical embodiments of the present invention and in which similar reference characters designate corresponding parts throughout the several views: I i W Figure 1 is a' semi-diagrammatic elevation showingv essential parts'oi the; machine, and a flpreferredmounting or arrangement ofthework forming dies therein; Figure 2 is a front elevation;

. Figure 3 is a detail side elevation of one o fia I pair of opposed dies shown in Figures l and 2;

Figure 4 is a similar side elevation of one of the other pairof dies shown in Figure 2;

.Figure 4A is a semi-diagrammatic View illustrating a modified form of the thread rolling. dies.

Figures 5 to 10,'inclusi ve, are semi-diagrammatic views similar to Figure 1 illustrating successive stages in the cycle of, operation of the machine; v v e Figure 11 is a detail elevation partly insection showing the adjustable work rest blade associated with each pair of dies for correcting taper of the work piece; 1 v 1 Figure 12 is a fragmentary plan view of oneof the dies and the adjustable work rest blade disposed in the position shown in Figure 11; Figure 13 is a semi-diagrammaticview'shewing one'form of driving mechanism for the work ii m di Figure 14 is a front elevation partly in section illustrating the mechanism at the Work receiving station; and

Figure 15 is a side elevation partly in section more particularly illustrating the mechanism for directing the work blank to and positively displacingrthe furnished work piece from the work forming station.

Referring first to Figures 1 and 2 of the drawings, upper and

lower shafts

32 and 34 respectively are suitably journalled in the machine frame. Preferably these'shafts are also laterally spaced apart so that the center line A intersecting the axes of said shafts is obliquely inclined at a substantial angle. The machine frame includes the two sections and 22 respectively provided with the

concave surfaces

24 and 26 substantially concentric with the respective shafts .32 and 34. In the embodiment of the invention which has been selected for purposes of illustration, on each of the shafts 3,2 and .34 axially spaced apart die members 28 and 13B are keyed or otherwise suitably fixed. These members are of gen- .eral cylindrical .form and are retained in spaced plied, with the proper relative location of the peripheral work forming means on said pairs of dies, to'successively produce the desired forms on spaced sections of the work blank in each revolution of said dies. As seen in Figure 1, the

corresponding die members

28 and 30 are peripherally opposed to the concave surfaces 24 and 2% respectively of the frame members and, in co- 7 operation therewith, form circumferential transfer paths for the work piece, as will be later explained; a

In-the illustrated embodiment of the invention, the dies 2-8 and 30 in each pair serve the dual purpose of transferring the work blanks to and from the work forming station between the dies and also producing the desired structural form on the work piece. .For the latter purpose, in the present instance, the dies in each pair are provided with peripheral means for forming a continuous screw thread on the work blank.

However, it will be understood that the die members may be provided with other forming means for knurling the work blank or producing a pcripheral surface thereon of any desired predetermined configuration. 7

To the above end, each of the die members v.28 .is provided with a notch 38 opening upon the periphery thereof, and which is of sufiicient depth to receive and retain a workpiece for rolling contact with the

concave frame surfaces

24 and 26 respectively in the work transfer operation of the dies. As shown in Figure 1 of the drawings, the shafts 3.2 and 34 and the die members mounted thereon are rotated in a clockwise direction and at equal speed. Therefore, each of the dies 23 is provided upon its periphery witha predetermined number of thread forming serrations 49, beginning atone side of the notch 38 and extending therefrom in a counter-clockwise direction for f approximately 180 of the circumference of. the die. These serrations are of the same general 'cross sectional form throughout their length, and

are circumferentially continuous without interruption or structural deformation of any kind.

As the screw thread must be gradually formed on the work piece as it is subjected to rolling pressure between the dies 28, the starting or lead ing ends 4! of the serrations 40 have an outer diameter which is such that, when these peripheral portions of the two die members are in substantially opposed relation, an unthreaded work blank will fit loosely therebetween. The outer and inner diameters of the thread serrations 46 are parallel and gradually increase or extend eccentrically with respect to the die axis to an intermediate point in their length. From this point, to the other ends 43 of the serrations 40, the major and minor diameters of said serrations are constantly parallel and concentric to the die axis and when the work piece completes slightly more than one revolution beyond said eccentric portions the thread will be fully formed on the work piece. During the latter peripheral travel of the die members relative to the work piece, no further radial displacement of metal takes place but the flanks of the thread thereon are smoothly finished to provide a final thread on the work piece of the required predetermined size and form. As is well understood in the art, the diameter of the blank upon which the thread is to be rolled is approximately half-way between the major and minor diameters of the resultant thread. Since it is evident that the work piece is rotated in a counter-clockwise direction between the dies at a relatively high speed, the finished thread will have been formed to its full depth on the work piece in .approximately of peripheral travel of the die members. The remaining cylindrical circumferential surface .39 of each die 28 is concentric with the axis of rotation and is of such diameter, that when these portions of the two die members are in opposed relation, la finished work piece will fit loosely therebetween.

It will be apparent from the above description that after the work blank has been introduced to rolling position between the dies 28,, a completely finished thread is rolled thereon during the first half revolution of said die members while the following half revolution of said die members is idle with respect to the work piece.

As shown in Figures 2 and 4 of the drawings, each .die member 39 is also provided with a work receiving notch or recess dz substantially identical in form or shape with the notch 38 .in the corresponding die member .28.. Each of these die members is also provided with a predetermined numberof peripheral thread forming serrations 3 3, but it will be noted, from reference to Figure a, that in this case, the starting or leading ends 1! of said serrations are located substantially, diametrically opposite the work receiving notch 52 and merge into the cylindrical surface 41. 7 As in the case of the dies 28 the outer .and inner diameters of the serrations 44 progressively increase in the counter-clockwise direction with rereceive an unthreaded part of the work blank therebetween when said surface sections are in cpposedrelation. V J V "Of course,- as is clearly seen in FLgmfe,; 2 ,-;0j;

the drawings, the thread forming serrations upon all of the die members are disposed at an angle with respect to the axis of rotation which is substantially equal to the helix angle of the thread to be formed on the work piece.

As the diameter of the dies is usually much greater than that of the work piece, multiple serrations are provided on the dies for the required number of starts necessary to create the correct helix angle, and therefore thread lead on the work. Thus, if the pitch diameter of the finishing thread on the dies is five times the pitch diameter of the thread on the finished work, then a quintuple or five start forming thread must be provided upon the thread rolling dies.

Referring again to Figure 2 of the drawings, it will be noted that the two die

members

28 and 30 are mounted on the

respective shafts

32 and 34 with the

notches

38 and 42 respectively thereof in the same radial position relative to said shafts and therefore in alignment with each other axially of the shaft, The threading

serrations

40 and 44 respectively adjoin the

notches

38 and 42 at relatively opposite sides thereof. Therefore, while a thread is being produced upon one portion of the work blank between the dies 28, anaxially spaced portion of the work blank rotates loosely between the dies 30. Thus when the dies 28 have completed the rolling of the thread on one portion of the work blank 46 and continue to rotate idly with respect thereto, a second thread is being formed on the portion of the work blank 46 disposed between die members 30. By providing appropriate thread forming serrations on the two sets of die members, this arrangement permits the threading of widely different diameters on the same work piece with different thread pitch and lead, which would obviously be impossible if the attempt were made tosimultaneously roll both threads on the work piece.

Of course, if it is desired to roll only one thread on the work blank, the other pair of die members may be formed with entirely cylin- I threaded at any given time, and the threading of allsections completed in a single revolution of the die members. Further, it will be apparent that in providing a single thread on a work piece, using a single pair of dies, the threading serrations on the dies may extend continuously around the circumference thereof except for that portionoccupied by the work transfer notch.

Also, if desired multiple work transfer notches may be provided in the dies so that a number of work pieces may be successively threaded by the serrations extending between the notches in a single revolution of the die members.

In Figure 4A of the drawings,I have shown a a modified form of the thread rolling dies in which only one die 28a has thread forming serrations 40a similar to those of the die 28 shown in Figure 3. The other die member 281) is provided with serrations 40b on approximately 180 of its periphery the major and minor diameters of which are concentric to the die axis through- .out the length of the serrations.

n, r in 6 the eccentric portions of the serrations 40a all allowances are made so that a full depth thread is progressively formed on the work blankas the latter is rotated in a partial revolution of the die member 28a in the mannerabove described. The work blank is also urged laterally against the serrations 40b of the die member 1 28b so that these serrations'aid in forming and finishing the screw, thread on the workpiece.

As seen in Figure 1 of the drawings, a work rest blade 58 is disposed between and suitably mounted upon one of the

frame sections

20 or 22. In this instance I have shown said blade mounted on frame section 22 and disposed in a plane substantially normal to the center line A between the axes ofshafts 32 and 34. In opposed relation to the blade 48 a fixed-guide blade 52 is suitably supported in another section 58 of the machine frame.

The work rest blade 48 is so adjusted relative to the center line A of the dies that the high speed rotation of the work piece in a direction opposite to the rotation of the dies produces'a force component tending to constantly urge the work piece laterally and hold the same in contact with the adjacent edge of the blade 48 so that the axial center line B of the work piece and the point of tangential contact of the dies therewith is slightly spaced from the center line A of the dies towards the blade. 48. Thus the possibility of undesirable relative movement between the dies and the work piece is eliminated. A Work rest blade 43 and a guide blade 52 is provided for each pair of dies, and it will be understood, that the beginning of the threading operation, the work blank is of substantially smaller diameter than the space between the

blades

48 and 52 so as to allow for the increase in work diameter resulting from displacement of the metal stock in forming the thread.

In Figure 11 of the drawings, I have shown means for individually adjusting the work rest blades 48 associated with the respective pairs of threading dies so that the taper of the work piece being threaded between one pair of dies may be corrected without disturbing the situation existing between the other pair of. dies. For this purpose, a number of screws 54 are adjustably threaded in the frame member 22 and by relatively adjusting said screws, the inner end 55 of the work rest blade having contact with the work piece, may be disposed at any desired predetermined angle relative to the axes of. the die members as shown in Figure 12. These adjusting screws of course prevent any movement of the blade 48 in a direction perpendicular to the center line A of the dies. It will be apparent that by properly adjusting the blade 48, the work piece will be positioned between the dies with its axis at one end thereof disposed closer to the center line A of the dies than at the opposite end' of the work piece. Thus the end of the work piece nearest to the the center line of the dies will be compressed to a relatively small diameter which progressively increases with the divergence of the work piece axis from said center. lineto the opposite end of the work piece.

While any preferred means may be provided for driving the work forming dies, in Figure 13 of the drawings, I have shown for this purpose a suitable motor 56 which transmits power to a shaft 58 by means of belts 69. This shaft carries spaced bevel gears 62 and 6 3 respectively, the former being in constant mesh with a bevel-gear o the t at. 6 d seas s; a ht ea t beneath the thread rolling station an threaded ends of the work piece it drop into shaft 58. The shaft 68 carries a worm it having driving engagement with worm wheel 12 suitably secured to the die driving shaft 32. A shaft 76 having one or more universally jointed sections I8 is driven by a gear HI which is in constant mesh with the gear 94. Oneend portion of the shaft i5. is provided with splines 89 slidably engaged with similar splines internally formed on the telescoped tubular end 83 of a shaft 82 which drives the other die carrying shaft 34 through worm M and worm wheel 86. Thus the flexible shaft 1-6 permits the

shafts

32 and 34 to beangularl-y adjusted relative to each other and maintained in exact parallelism despite unequal wear of the shafts and their bearings while the telescopie connection 83 between shaft 16 and shaft 82 enables the distance between the axial centers of

shafts

32 and 34 to be varied in accordance with work of different .diameters.

' In Figures 5 to of the drawings, I have diagrammatically illustrated the successive stages in r a complete operating cycle of the machine, to

which reference should now be had. The work blanks are supplied at the top of the machine by means .of any suitable automatic device of the hopper or magazine type to the entrance opening 88. When the notch38 in the upper die 28 arrives at the position shown in Figure 5, the work blank drops through the opening 38 into said notch. It will of course be understood that if spacedsections of a long work blank are to be threaded, one end of the blank will be received in the notch 42 of the corresponding die member 36. In the continued clockwise rotation of the upper die, the work piece is moved downwardly by said die in a circumferential path in rolling contact with the surface 24 of frame member 25, until the notch 33 arrives at the position seen in Figure 6 when the work blank 46 will drop downwardly from said notch into a position between the work rest blade 4.8 and theguide blade 52.

It will be noted that at this time the notch 38 of the lower die .23 has arrived at a position beneath the inner opposed ends of the

blades

38 and 52 somewhat ahead of the notch in the upper 7 die so that the work blank positioned between the blades 4.8 and 52 rests upon the leading ends iI ofthe thread forming serrations do on the lower die 28. The thread. rolling operation now begins in the continued rotation of the dies upon that part of the blank which is disposed between the dies 28, it being understood that the other portion of the blank '48 between the die 36 is idly rotating betweenthe cylindrical portions of the latter die-s Figures 1 and '7 ofthe drawings show the threading operation somewhat more than half completed. As the dies continue to rotate, the threading of the blank section between dies 28 is completed with a final forming and finishing operation of the thread as above explained. The other pair of dies 38 now begin to form a thread on the other portion of work -piecef45, during which time the finished thread on the work piece idly rotate-s between the cylindrical portions of dies 28 as shown in Figure 8 while a second work blank G9 enters the notches in the upper dies '23 and 3b. 'In the final half 7 revolution of the dies, this second threading operationon the work piece between dies 39 is com pleted, at which time, as shown in Figure 9, the notches in the lower die members 28 and 3% arrive the said notches'while work blank 45 is'at the point yof 'release from thenotches'of the upper dies 28 and--30 to drop into the space between" the blades 4.3 and .52. In the succeeding first half revolution of the upper and lower dies, as work blank 49 is threaded by the dies 28, the finished work piece "35 is transferred in a circumferential path and in contact with the surface, 2-6 of frame member 22- and discharged from the machine as seen in Figure 10, approximately at-the time that the formation of the thread on'work piece 49 is completed by the dies 28.

In Figures 1a and 15 .of the drawings I have shown mechanism for positively singly delivering work blanks from a magazine to the work receiving notches of the upper die member instead of by gravity and also for positively ejecting the finished work piece from the work formine Station'into the transfer'notches of the lower die members. On the drive-shaft 32 of the upper dies a cam is suitably fixed and has peripheral contact with a roller 92 mounted in the lower end of a rod 9!! vertically movable through a suitable guide opening in part 950i themachine frame. At its upper end, opposite sides of this rod are provided with rectangular. grooves or channels 98 receiving the slidable blocks or shoes I89 pivotally mounted on the inner sides of the arms of the bifurcated end of a lever m2, as shown at I04. This lever intermediate of its ends is pivotally mounted as at me upon the upper end of .a post 56% fixed. in the frame part 96.

The otherend or" lever I92 similarly carries the blocks or shoes .i i2 mounted on pivot pins lit, said shoes being slidable in the horizontal grooves or channels i IS in opposite sides of a plungerrod H4, the lower end of which is movable between the upper die members 23 and 30.

A collar M8 on the rod Ild bears upon the upper end of ,a compression spring i253 mounted in recess 122 in the frame part 96. This spring constantly urges plunger I I4 upwardly, therefore transmitting downward movement to rod .94 and maintaining resilient contact of roller 92 with the periphery of cam 96.

ihe lower end of the plunger lid is vertically movable in closely adjacent relation to the egress end of an inclined chute or magazine I 24 for a column of work blanks, as seen in Figure 15 of the drawings. This end of theplunger is formed with a notch or recess I26 which, in the normal raised position of the plunger rod lid, receives the lowermost blank from the chute I2 5. Either manual or automatically operated means may be provided for loading the magazine chute.

It will be understood that the cam 3% is so arranged on shaft 32' and is of such configuration; that at the time'th'e notches 38 and ilZ'of upper dies 28 and 30 arrive at theposition shown in Figure 15 said cam forces rod 9. 5 upwardly and 1 moves plunger I I 3 downwardly against the ,re-

sistance of spring i29 to carry a single work blank below the egress end of chute I24 and position the ends thereof in the notches of said die members, from which it is carried and transferred to the work forming station by said upper die members in the manner previously explained. The cam 80 then permits the spring I29 to force plunger rod I I upwardly returning the same to its original position to receive another work blank from chute I24.

As seen in Figure 15 of the drawings, the work guiding member 52 above described has been replaced by the guide member I32 having a stem provided witha T-shaped head'for engagement in a T-slot I30 formed in the machine framepart I28 which corresponds to the frame section 50 9 and lower pairs of dies and after adjusting the same laterally along the T-slot I36, it is locked in position by means of a nut I34. An upwardly extending wing I36 of this guide member has an inclined edge surface facing the direction from which the work piece 46 arrives at the threading station between the dies. Contact of the work piece with this wing of the guide member results in the work piece being positively removed or displaced from the notches in the

upper die members

28 and 38, assuring its proper deposit in threading position between the upper and lower die members.

I have also provided a mechanism for positively forcing or ejecting the finished work piece from the threading station into the notches of the lower die members. For this purpose, cam mem ber I38 is suitably fixed to shaft 34 and is of concentric circular outline except for the notch or cavity I48 formed in the periphery thereof. An axially movable follower rod I44 is mounted in frame part I42, and roller I46 journalled on pin I48 in one end of this rod is in constant contact with the periphery of cam I38. The opposite end of the rod I44 is pivotally connected as at I50 with one arm of a bell crank lever I52 journalled on fixed pivot I54 suitably secured to the machine frame. The other crank arm has bearing engagement at its extremity against the head of the screw I56 which has threaded engagement in the lower end of a sleeve I58 and is adjustably locked in position relative thereto by nut I60. 7

The sleeve I58 has axial sliding movement in a bore I62 formed in the frame portion I28. The upper end portion of the sleeve I58 has a cylindrical bore I64 receiving a washer member I66 and a spring I68. A screw I18 secures washer I66 to the lower end of a rod I12. A washer I14 is seated in the upper end of bore I64 in the frame part I28 around the rod I12 so that the spring I68 is held under compression between said washer and the washer member I66 to constantly urge sleeve I68 and rod I12 downwardly and hold roller I46 in contact with the cam I38.

The rod I12 at its upper end is formed with a rectangular enlargement which is bifurcated to receive one end of an ejector member I16 mounted upon the pin I18. This ejector member projects inwardly between the

upper die members

28 and 30 in a downwardly extending are, as seen in Figure 15, and is yieldingly held in its normal position by means of a spring I86 carried by the rod I12 and bearing at one end against a shoulder I8I on the ejector member I16. In this normal position the ejector member I16 is constrained by the force of spring I68 to press at its free end against the work piece 46. This pressure 110wever is very light due to the limiting action of spring I68 and bell crank lever I52. Rocking movement of member I16 in counterclockwise direction on the pin I18 from its normal position is prevented by contact of the outer end of said member against the abutment surface I11 of rod H2 at one side of the pivot pin I18. At the opposite side of said pin, the end of rod I12 has a bevelled surface I19 permitting of limited clockwise movement of the member I16 against the resistance of spring I86 for a purpose which will presently appear.

It will be apparent from the above that when the depression I40 of the cam I38 receives roller I46 and allows the crank I52 to rotate, the pressure of spring I68 urges the ejector I16 downwardly as a unit with rod I12 and causes said ejector to force the workpiece downwardly into the notches of the

lower die members

28 and 30. The return of the ejector I16 to its normal position occurs when roller I46 moves out of the cavity or depression I40 in the cam member, thereby compressing the spring I68 as the screw Ice and sleeve net are forced upwardly by the crank I52. In this upward movement of the member I16, the spring I86 permits the inner free end of said ejector member to move downwardly to clear the second workpiece which has arrived at the thread rolling station while the finished workpiece was being ejected and discharged.

By the provision of such automatically operating mechanism as above described, rapid and positive transfer of the workpiece from the receiving to the working forming station and from said station to the discharge station is insured,-

while the cutting dies may be operated at higher speeds than would otherwise be permissible.

From the foregoing description, it will be appreciated that I have provided a very novel method and apparatus whereby the quantity production of rous, bolts and similar workpieces having one or-more parts thereof provided with screw threads or other desired structural formations, may be greatly expedited. By utilizing the rotating the members Ior the purpose of automaticaily transferring the workpiece between the several machine stations in closely timed relation with the thread forming operations of the die members, the time loss incident to the use of separate transfer mechanisms Ior discharging the finished workpiece from the machine and for transferring a new workpiece from the hopper or other supply source to the Work forming station, are avoided. In the forming of ascrew thread on a workpiece, the novel construction of the threading serrations on the die members insures an accurately formed and perfectly finished thread on the workpiece. The adjustable work rest between the die members for accurately positioning the workpiece to correct or control the taper thereof is also an important feature of the invention; The mechanism for insuring the positive displacement of the workpiece relative to the dies to and from the work forming position enables the machine to be operated at maximum speedand is therefore a material aid to large quantity production. Finally it will be noted that the described apparatus provides a very compact and efiiciently operating organization of the several mechanical parts, the initial production cost of which is comparatively low while the operating and maintenance expense thereof is reduced to a minimum.

The invention may be embodied in other spe- I cific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and. not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In apparatus for sequentially threading axially spaced portions of different diameter one.

work blank, a plurality of pairs of dies, means mounting the dies of each pair in peripherally opposed relation and mounting the corresponding dies in each pair for unitary rotation in axially angers spaced apart relation, said correspondin dies each having a smooth peripheral portion and having work forming means of relatively different diameters extending partly about its circumference at relatively opposite sides of the axis of the respective dies for pressure forming contact at different times with different axially spaced portions of a work blank positioned between the dies in each pair, said forming means on the dies in one pair simultaneously operating upon one of said portions or the "work blank while the other of said portions of said work blank are supported by saidsinooth peripheral portions of said other pairs of dies, means for rotating said pairs of dies in the same direction at equal speeds, and means carried by said Corresponding dies respecmay operable to transfer a work blank from a receiving station to forming stations between the dies of the respective pairs, and to transfer the formed work blank from said formin stations to a discharge station. v

2. The apparatus defined in claim 1, in which said transier means comprises peripheral axially aligned notches in the corresponding dies receiving said spaced portions of the work blank.

' 3. In combinatiOnQupper and lower Work forming dies in peripherally opposed relation and means for rotating said dies in the same direction, each of said dies having a peripheral work transfer notch, a member mounted for bodily angular movement relative to the dies and having means operable in one position thereof to hold the work blank in forming position between the dies, means for moving said member from the latter position to move the'work blank from the forming position into the notch of the lower die, and means controlling the operation of said last named means operable in timed relation with the rotation of the dies.

4. In combination, upper and lower work 'forming 'dies mounted in peripherally opposed relation to provide a work forming station between said dies, means for rotating said dies, each of said dies having a peripheral work receiving notch, relatively movable means for directing a workpiece from the notch 'in said upper die and sfiippdrtin'g :said work piece at the Work forming station, and means for actuating said relatively movable means in timed relation to the rotation of the "dies 'to release the 'formed workpiece for movement into the work receiving notch of the lower'die;

5. In apparatus for forming asorew thread on aworkbl'ank, a machine frame, vertically spaced peripherally opposed dies 'rotatably mounted in adjacent relation to concentric guide surfaces on said frame and each having thread forming ser-, rations extending partially about the circumference thereof, each of said dies havin a peripheral work receiving notch immediately adjoining the leading ends of said serrations, and means for rotating said dies in the same direction and at equal speeds, said notch in the upper die transferring a work blank from a work receiving station in rolling contact withone guide surface on the machine frame, relatively stationary means for ejecting said blank from said notch in said upper die and delivering said blank between the leading ends of said serrations on the dies, and means moving in timed relation with the movement of said dies for moving a formed work piece 12 l V away from the upper die and into the notch of the lower die for movement therewith in rolling contact with the other guide surface on said frame to a dischargestation.

6. Apparaus for rolling screw threads of relatively difierent pitch on axially spaced parts of a work blank having difierent diameters, comprising two pairs of rotatably mounted 'dies 4 axially spaced apart, with the dies in each pair 10 in peripherally opposed relation and each die having thread rolling serrations extending about its circumference for not more than degrees and of diiierent diameter from the serrations on the other pair or dies, each die also having a smooth peripheral section extending about another portion of its circumference, said serrations on the axially aligned die members being disposed at relatively opposite sides of their axis of rotation, whereby the serrations of the respective pairs of dies havealternate thread *roll ing engagement with the spaced parts of the-work blank disposed between the opposed die members during different periods of time, one of said parts of the work blank being'supported for idle rotation between the smooth peripheral sections of the dies of one pair, while the other pair of dies is in thread rolling engagement with the other part of the work blank, and means for rotating the dies in each pair in the same direction and at equal speeds.

"7. Apparatus for sequentially threading axially spaced portions of a work blank comprising, at least two pairs of dies, each of said dies having thread rolling serrations extending about a portion of its periphery for not more than 180 and having a smooth peripheral section extending about another portion of its periphery, said serrations of one pair of dies being of different diameters than the serrations on the other pairs of dies, rotatable mounting means for mounting the dies of each pair in peripherally opposed relation, each die of one pair being in spaced coaxial relation with a die of the other pairs, said mounting means being arranged to dispose the serrations on the said spaced coaxial dies at relatively opposite sides of the axis of rotation of said mounting means, and means for rotating said dies in the same direction at equal speeds whereby said work forming means of one pair of dies will be in pressure forming contact with one of said axially spaced portions of the work blank while the smooth peripheral portions of the other pairs of dies is in supporting contact with a different portion of said work blank.

CECIL W. HOPKINS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS