US2624218A - Thread rolling machine - Google Patents

Description

Jan. 6, 1953 R. E. FLANDERS ET AL THREAD ROLLING MACHINE 6 Sheets-Sheet l www im 7' Filed Feb. 4, 1946 V @QW Jan. 6, 1953 R. E. FLANDERS ET A1.

THREAD ROLLING MACHINE Filed Feb. 4, 1946 6 Sheets-Sheet 2k Illlll Jan. 6, 1953 R. E. FLANDERS Er AL THREAD ROLLING MACHINE 6 Sheets-Sheet 5 Filed Feb. 4, 1946 Jan. 6, 1953 R. E. FLANDr-:Rs Er AL 2,624,218

THREAD ROLLING MACHINE Filed Feb. 4, 194e e sheets-sheet 4 Jan. 6, 1953 R. E. FLANDERS ET Al.

THREAD ROLLING MACHINE 6 Sheets-Sheet 5 Filed Feb. 4, 1946 Jan. 6, 1953 R. E. FLANDERS Er AL THREAD ROLLING MACHINE 6 Sheets-Sheet 6 Filed Feb. 4, 1946 l u Mw m \1 t Q afi, I; YQ K. m Sl t NW/ s V Jh J l 1 ww N E w E o. S o o A o o o e o o o SQ w i .0 w 0 0. 0 K. Y N W YQ Patented Jan. 6, 1953 l l 2,624,218 THREAD ROLLING MACHINE Ralph E. Flanders, Springield, and James W.

Batchelder, Weathers Jones & Lamson Mac ield, Vt., assignors to hine Company, Springeld, Vt., a corporation of Vermont Application February 4, 1946, Serial No. 645,314

1ov claims.

crease the capacity of the machineby utilizing' opposing thread rolling penetrating forces to act simultaneously on more than one work blank during the rolling operation.

A further object is to positively control the rate of penetration of the dies into the work blanks over a wide range of adjustment. f

A further object is to provide a mechanical over-load relief protection against over-stressing of the mechanism or of the dies due, for example, tooccasional oversize blanks.

A still further object is the provision of a penetration energy storage system so arranged that the power required to cause the dies tofpenetrate the work is drawn from the motor or prime mover during the feeding interval of the cycle/at which time the motor would otherwise be substantially idle. The energy storage system is so arranged that the penetrating energy is delivered at a time when the motor is fully occupied in revolving the dies and acts to augment the penetrating power exerted by the rotation of the dies.

A further important object of the invention is to cause this energy storage meansvtoA release its energy to coincide approximately with the requirement that the penetrating force increases as the penetration progresses.

Another object of this invention is to utilize the mechanism for accomplishing the three last objects in a single mechanical system ordei'j to simplify the mechanism and to increase its dependability in operation.

Still another object of the invention is to provide means which greatly facilitates thesettirig of the positions of the dies to any given diameter of work, such means being adjustable while the machine is in operation. A further object is to provide for widely varying the frequency of the penetration strokes without stopping the machine, the adjustment.

for this purpose being independent of the speed V,of rotation of the dies.

Still another object is to combine the speed varying changes of hydro-mechanical systems with the inherent characteristics of toggle mechanism, the latter possessing the desirable char- 1 acteristio or increased mechanical advantage as dead center is approached, which corresponds nicely with requirements of increased penetratj` ing force with increased penetration depth` For a complete understanding of this invention, reference may be had to the accompanying drawings in which Figure l lis a front elevation partly broken away of a thread rolling machine embodying the invention.

Figure 2 is a top plan view of the same.

Figure 3 is a detail sectional view on line 3-3 of Figure 2. f

Figure 4 is a left end elevation of the same partly broken away.

Figures 5 and 6 are sectional views on lines 5-5 and 6 6, respectively, of Figure l.

Figure 7 is a detail' sectional view on line 1--1 of Figure 6. f

Figure 8 is a detail sectional view on line 8-8 of Figure 5, the parts being shown near the end of a rolling operation.

Figure 8a is a Vdetail sectional view on line Sa-Sa of Figure 8. .Y

Figure 9 is a diagrammatic view of the actuatling mechanism turing the penetrating stroke.

Figures 10 and ll. are fragmentary diagrammatic views showing certain of the parts in diewithdrawing and machine-stopped positions, respectively.

Referring first to Figures 1 to 5, at I is indicated a bed, to the upper and front faces of which is secured a frame 2. Both ends of the frame at the top are provided with parallel ways or rails 3 upon which are mounted a pair of carriages or die heads 4. These carriages are held down to the rails with hold-'down gibs 5 (see particularly Figure 4). The front gibs are adjustable to take up lost motion.

Each of the carriages or die heads 4 has journaled therein, transverse to its direction of motion, a shaft 9 r(see Figure 2) supporting a cylindrical thread rolling die 6, and these dies 6 are arranged about the axis of a similar die 1 carried by a shaft 8 arranged parallel to the shafts 6 and situated between them. Each of the dies 6 may be carried on a conical adapter l0 of the type shown in the Batchelder application for Letters Patent Serial No. 557,350, filed October 5, 1944, and now abandoned, for Thread Rolling Die Construction. Each o'f the shafts 9 is journaled at its largest diameter portion in the bearing I l `and at its forward end in an outboard bearing I2 which engages the tapered forward end of the shaft 9. l

The shafts 9 are permitted limited end play in order to permit automatic adjustment lto correct minor inaccuracies in phasing between the centra1 die and the carriage-carried dies 6. f To this 'thickness that the ring 3 end the rear end of each of the shafts S is recessed at I5, and within the recess a bearing I6 is mounted, this bearing being seated against an annular shoulder il in the recess, and held there by a sleeve |8 threaded into the outer portion o f the recess. The bearing member Il has bearing against opposite end faces thereof, collars I9 and 2E) against which springs 2| and 22 bear. IIhese springs at their extreme ends bear against collars 23 and 24, pinned to a rod 25 which is adjustably secured as by being threaded into a cap covering over the outer face of achamber 3|. Within the cha-mbei 3| in bearings 35 and 3S is journaled the hub 32 of a worm wheel 34, this worm wheel being keyed to the shaft 9 as by the long key 31. Thus by rotation of the correspondingworm wheel the shaft time this shaft is permitted some end play, the springs 2| and 22 tending to center the shaft 9.

Suitable means are provided for forcing the carriages 4 toward and` from each othenthe forcing of the carriages toward eachother acting kto force the outer rotary dies 5. toward the inter- .mediate die l and thread work pieces placed j between these dies. The total amplitude of motion of each of the carriages 4 is on the order of a 1A; of an inch, and in order that the initial settings of the dies 6 with reference to the die 'l maybe S may be rotated while at the same made in accordance with the size of the work piece and the size of the dies, the means for forc- -ingthe carriages toward and from each other are adjustably secured thereto.

The forcing means for each of the carriages 4 comprises an eccentric 43 having journal extensions 4| mounted in suitable .bearings in the frame 2 and adapted to be rocked as by turning of a crank arm 43 connected to oneof the journals 4|. An eccentric rod 44isjournaled onI each eccentric and near its outer end it is provided with a journal portion 45 extending from oppositer sides thereof. The journal portions 45 are journaled in a cylindrical block 46 which is surrounded by an externally threaded sleeve 4l'. This sleeve-47 is threaded into an outer sleeve 48 which is xed to each carriage 4. By rotation of the inner sleeve 41, the block 45 may be adjusted axially relative to the sleeve 43 and the carriage 4, and thereby the limitsof the path of motion of the carriage 4 may be adjusted as desired. In. order to take up backlash between the sleeves 4l' and 48, an externally threaded ring 59 may be engaged with the threads of the outer sleeve 48 and connected for rotation with the inner sleeve 41, as by suitable pins 5I which extend through thering 59 and into the sleeve 4l. A ring 52 around the eccentric rod 44 is secured to the inner end of each block 46 as hy screws 55, shims 55 being interposed between the two. These shims are chosenv of vsuch may engage the threaded ring 553 when the threaded ring 55 is in such angular position that it takes up the slack betweenthe threads or" the sleeve 48 and the sleeve 41 and the ring 55. By this means lost motion betweenV the sleeves 47 and 48 may be taken up, while the relative adjustment axially between these sleevesdetermines the inner and outer limitsl of motion of the vcorresponding carriage 4 when it is reciprocated by the rocking of the eccentric 4l).

The adjustment between the sleeves 4'! and 48 may be fixed when desired, means for doing so comprising oppositely disposed radially arranged locking pins 60 extending through radial openings in the block 46, the inner ends of the rod 60 bea-ring against the inclined face 6| of a screw plug 62 threaded into the outer end of the block 46. By tightening this screw 62, the inclined faces 6| riding against the inner ends of the rod 5t force these rods outwardly with their outer ends into tight engagement with a ring 65 secured. to an outwardly .directed fiange 56 on the sleeve 41, as by screws 58. A tubularhs'hield B9 overlies the inner sleeve 4l and overlaps the sleeve 48 and may have graduations thereon which may be brought into registry with a datum line marked on the outer sleeve 43, as shown best in, Figure l. This means provides a micrometer adjustment for the end positions of the carriages so Vthat accurate adjustment of threadsizes on the work is readily accomplished.

Means are provided for rotating the dies to thread the work. As shown best in Figure 2, the

central die carrying shaft 8 is provided within a housing '1G with a worm wheel ll secured thereto-and adrive shaft 'i2 is connected asby a ,coupling 'E4.to..a Worm shaft 7,3 vhaving a worm meshing with the worm wheel il.. The outer end of the drive shaft 'i2 extends'intov a gear box' V75v and carries a gear it meshing with a gear T1 on a stub shaft-'i8 in the gear box, this shaft Tl also meshing with a gear i9 on a drive shaft 8B positioned forwardly of the drive shaft 'l2 and having connections for driving the die shafts 9. Such connections areshown in Figure 3. The shaft 8d is connected through acoupling 82 with a second` hollow shaft 83, the coupling 82 permitting the angular relationships vbetween the shafts Sil. and S3 to be adjusted. Shaft 83 is slidably keyed to a sleeve |34v to which is keyed a wormgear 85. The sleeve 84 is journaled in the wall of the chamber 3| which houses the'worm wheel 34 with whichv the worm gear 85 meshes.

YSimilarly the endportion ofl the shaft 8G is con.-

,for the passage of lubricant extending to the keyed connectionsthe head of the bolt closing 01T the outer end of the shaft 83. This arrangement provides for rotation of all of the dies while permitting the dies 5to be moved from and toward the central die by the sliding motion of the carriages.

The dies are rotatedand the entire machine is driven by a motor 60 supported on the hinge table 6| which is adjustable as by manipulation of the nuts |t2 on anchor bolts |533. The motor Illu isprovided witha belt pulley |4 about which a belt |55 passes, this belt also engaging over a pulley Idd carried by the shaft le?. This shaft |61 and a shaft H9 have change gears I|| and I 2 thereon in a change gear box 3 which forms an extension of the gear box '55, and a gear H4 on the shaft Il meshes with a gear 5 on the shaft '|'2.

The carriages 4 are moved from and toward each other and relative to the intermediate die by rocking of the eccentrics 4d as previously described. As they approach die closed position 'their centers approach alinement with lines connecting the axes of their bearings in the rods work. The mechanism for so rocking these eccentrics is shown particularly in Figures '7, 8, 9

and 10. The eccentrics 4|| are rocked by the rocking of the arms 43, these arms being pivoted to the upper ends of links |20. The lower end of each link is pivoted at |2| to the upper end of a plunger |22 which is connected to a spring loading device indicated generally at |23, and the lower end of which is anchored by being pivotally secured as at |24 to the frame. This spring device may be constructed as shown in Figures 8 and 8a. As there shown, a pair of concentric coil springs |25 and |26 are located between top and bottom cap plates |21 and |23 having annular shoulders against which the ends of the springs bear. The plunger |22 extends slidably through the cap plate |21 and also extends through the cap plate |28 beneath which it has threaded thereon a long nut |32 which holds the sap plate |23 against an annular shoulder |3| of the plunger |22. A cotter pin |32 extending through a hole through the plunger |22 beneath the nut |39 may be employed to hold the nut |36 in position. The pivot |24 passes through an anchor member |35 having upstanding posts |36 connected by bolts |31 with the top cap plate |21. The cap plate |21 and the anchor member |35, together with the bolts |31, act as a cage within which the springs |25 and |26 are positioned.

This spring mechanism. constitutes an energy storage system which provides all the power for moving the corresponding carriage toward the central die and is tensioned by the motor when the motor is only lightly otherwise loaded when the carriage i-s moved to open position. It thus provides a mechanical overload relief protection against over-stressing of the mechanism or of the dies. Means for so tensioning the spring devices com-prises a central cam |46 with which coop-Y erates a pair of followers |4| at the inner ends of a pair of links |42. Each of the links |42 is pivotally suspended on the links |43 and |44 which are fulcrumed at |45 and |46, respectively, to the machine frame. The link |43 has a lateral extension |41 which is pivoted. at |43 to the link |20. The parts are so related that as the links |42 are pushed away from the axis of the 'cam mu, both of the links ne are lifted, causing the plungers |22 to be lifted and load the spring devices, and at the same time the arms 43 are rocked in a direction to retract the carriages from the central die. The cam |46 is se# cured tov an actuating shaft |56 (see Figure 5) journaled in the frame 2, this frame cessed at |5| for the reception oi a rack bar' |52 which engages a pinion |53 fixed to or integral with the shaft |52. This rack bar extends downwardly through suitable bearings |54 of the frame 2 and its lower portion is secured to or formed integral with a piston rod |55 carrying a piston |56 axially movable within a hydraulic cylinder |51. At the upper end of the cylinder |51, the piston rod |55 passes through a stuiiing box |53. The cam |46 is provided with a pair of concentric larg'e diameter portions |56, a pair of small ldiameter concentric portions |5|, clined connecting portions |62 between the large and small diameter concentric portions. When the cam follower rolls 14| are riding on the small diameter concentric portions, as shown in Figure 3, no motion of the links |22 occurs as the cam` swings, and the carriages are then in their advanced positions, As the cam followers ride upon the inclined cam portions |52, the links |42 are forced outwardly and the spring mechanisms are loaded and the carriages are moved outand in- 6. wardly. When the followers |4| are riding-upon the large diameter concentric portions |32, the spring mechanisms are held loaded and the carriages are stationary in their retracted positions. The length of time during which the carriages are held retracted and advanced is determined by stops |65 and ||i5aI adjustable in arcuate slots |66 and |56a in the cam |42, these stops limiting the extent of rocking of the cam by impingement against opposite sides of a valve actuating' arm |16 journaled on the shaft |53 and depending therefrom and which acts to reverse the direction of rocking of the cam as will later appear. Engagement of the stops on one or the other side of the arm |15 acts to swing the arm |16 in one or the other direction and acts to move a reversing valve actuating rod |12 through a load and re mechanism. rI'he load and re mechanism comprises a pair of sleeves |13 and |14 slidable on the rod|12 between a pair of collars |15 and |16 secured thereto, the sleeves |13 and |14 being normally and yieldingly held spaced from their respective collars by coill springs.Y |11 and |18. The arm |16 at its lower end engages a block |86 slidable on the rod |12 between the sleeves |13 and |14, andas thi-s collar |33 impinges on one or theother of the sleeves |13 or |12 and moves it laterally along the rod |12, it compresses the corresponding spring |11 or |123 and then engages and moves the corresponding collar |15 or |16 and the rod |12, overcoming the latching effect of a pair of spring pressed balls |52 arranged in sockets in the upper end ,of a valve casing |83 and engaging a Vvalve stem |34 provided with a pair of spaced annular grooves ISS and |86 within which the balls |82 may engage. As soon as the :balls |32 'release the Istein |84, the compressed spring |11 or |18 snaps the stem |84 to the other latched position which reverses the valve as will be described. The valve stem |84 is connected to the actuating rod |12 through a bell crank lever |22 fulcrumed at a fixed point |9I, `one arm of the bell crank lever being connected to the rod V|12 and the other connected through a link |92 to the valve rod |3fl. The valve rod |84 rides within the valve casing |83, which is provided with three lengthwise arranged ports |95, |96 andlQl. The valve port |36 connects to a source of iiuid pressure through a pipe |98. The valve port |31 leads through a lpipe |99 to the top of thehydraulic cylinder |51 above the 4piston |56. The upper port |55 leads through a pipe 22|) to a valve casing 25| from which extends a pipe 222 to the lower end of the cylinder |51 beneath the piston |56. A pair ofv check valves 263 and 231 normally close ports 264 and 225, respectively, opposite to the ports |25 and |91, the latter oi the-Se ports 255 leading to a discharge passage 2216. Fluid under pressure is taken from the supply tank 2|@ shown diagrammatically in Figures 9 and ll by a pump 2| |,which may be coupled to the shat of the motor |69, and forced into the pipe |93. The discharge pipev 255 leads to the tank 2li?.

i Assuming thalt the work pieces have been rolled and the stop |65 shown in Figure 8 contacts the arm |16 and turns it counterclockwise, this comn presses the right hand spring |16.y When positive contact is established between thesleeve |14 and the collar |16, the rod |12 is pulled to the right and through the bell crank lever |96 the valve rod |84 is pulled upwardly from the position shown in Figures 8 and 9 to the position of Figure 10. In this position of the parts the valve spool 2|5 blocks the uid flow from the Y discharge pipe 243 pressure pipe 98. to the porti |91 and opens pressure to the upper check valve 203 which allows the fluid to pass rthro-ugh the pipe 202 and beneath the piston |56. This causes the piston to rise, revolving the cam |40 in clockwise direction which spreads the cam followers |4| apart, compresses the spring mechanisms, and opens the die heads. These die heads are opened a distance sucient for the removal of fthe finished worl: piece and remain inthat position a sufficient time for the succeeding work piece to be Vpositioned betwfeen the dies and Ontothe vertically adjustable stock suppont |63 while the cam followers are riding upon the large diameter concentric portions |60 of the cam |40.

After the cani has been revolved in this clockwise direction for a suiiicient time, theotherstop l55a engages the right hand side of fthe shift lever |10, depressing the left hand load and re 'spring' |11. When this has been fully compressed and the valve stem starts to be moved positively, the spring |11 throws it to its opposite position shown in Figure 9. This causes the pressure line |98 to be opened through the pipe |99 to the upper end of the cylinder |51 which causes the piston to descend and revolves the cam |40 in couniterclockwise direction. Besides the uid flowing to the top of the cylinder, it also escapes past the check valve 201 to the reservoir.

The speed of descent of the piston and consequent rate of penetration of the work by the dies is controlled by regulating the rate of discharge from beneath the piston |56 which passes through the pipe 202 into the adjustable flow conitrol valve casing 20|. 'I'his casing 20| is provided with a throttle valve 220 which may be adjusted by manipulating a handle 22| on the front panel of the machine. This valve may be caused to more or less throttle a passage 222 leading from beneath the valve 223 to the line 224. This line 224 leads to the main valve casing, and in the position of the parts shown in Figure 9, it opens above the spool valve 2|5 and discharges into the passage and pipe 224 which leads back into the discharge pipe 206. Between the throttle valve 222 and the valve 223, a passage 230 extends ibeneath the piston 23| which is connected to operate the valve 223. Above the piston 23| a light spring 232 is positioned, this tending to open the valve 223. Above the piston 230 is 'a passage 235 leading to a point beyond the throttle valve 220. As the throttle valve 220 is more or less closed, it increases'the back pressure between this valve and the valve 223 which `acts to lift :the piston 23|, reaching it through the passage 230 and through the valve passage 236. This more or less throttles the port controlled by the valve- 223 and thus determines the rate of flow rto the discharge.

Mea-ns are pro-vided for limiting the pressure of the uid delivered by the pump to the hydraulic mechanism, and this means may also be utilized to stop the operation of the machine when desired. Referring to Figures 9 and 11, the pressure pipe |98 opens into a pressure relief valve casing 240. A valve 24| in this casing is spring pressed toward a seat 242 leading to the back to the supply tank 2|0. The valve 24| is spring pressed to closed position as by the spring 244 and a bleeder passage 245 extends through this valve it communicates through a pipe and passage 250 leading to a dump valve casing 25|. The pressure may be built up through this passage 245 and past a check valve 252 back of the valve 24|, this aiding the spring 244 in holding the valve to its back face where A closed. Should the pressure on the-right hand face of the valve 24| exceed a predetermined amount, this valve will` be pressed. to the left, opening the valve to the discharge pipe 243 so long as the pressure is above that for which the valve is set. However, by reducing the pressure on the left hand face ofthe valve through dump valve 25|, the valve 24| may be opened and pressure released from the pipe |98. This dump valve, as shown in Figures 9 and '11,. is a reciproeating spool valve 253 which in the position shown in Figure 9, o-bstructs passage from the pipe 250 to a pipe 254 leading to the discharge pipe 243, but by moving this valve 253 to the right into the position shown in Figure 11, the pipes 250 andV 254 are placed in communication so that thev pressure control valve 24| is opened and the hydraulic mechanism is rendered inoperative to actuate the piston |56.

From the foregoing description of an embodiment of this inventi n, it should ybe evident to those skilled inthe art that various changes and modicatio-ns might be made Without departing from the spirit or scope of this invention.

We claim:

1. A thread rolling machine including a bed, a pair of carriages movable from and toward each other on said bed, a rotatable thread rolling die journaled for rotation on each carriage transverse to their lines of motion, Va rotatable thread rolling die mounted on said bed between said carriage mounted dies and cooperating with each of said carriage mounted dies to roll threads in Work pieces placed therebetween, means connecting said dies for rotationA in phased relation including means for adjusting such phasing, means for moving each of said carriages toward and from each other, actuating means for said moving means including springs for actuating said moving means to move said carriages toward each other, and a rocking cam and a pair ofl followers on opposite sides of said cam for actuating said moving means toY separate said carriages and for loading said springs, said cam having for cooperation with each follower a pair of concentric portions of different diameters and an inclined portion joining said concentric portions, means for rotating said dies including a prime mover for rocking said cam in opposite directions, and means for adjustably determining the limits of rocking motion of said cam.

2. A thread rolling machine including a bed, a pair of carriages movable from and toward bed, arrotatable thread rolling die journaled for rotation on each carriage transverse to their lines of motion, a rotatable thread rolling die mounted on said bed between said carriage mounted dies and cooperating with each of said carriage mounted dies to. roll threads in work pieces placed therebetween, means connecting said dies for rotation in phased relation including means for adjusting such phasing, means for moving each of said carriages toward and from each other, actuating means for said moving means including springs for actuating said moving means to move said carriages toward each other, and a rocking cam and a pair of followers for actuating said moving means to separate said carriages and on opposite sides of said cam for loading said springssaid cam having for cooperation with each follower a pair of concentric portions of diierent diameters and an inclined portion joining said concentric porrotating said dies including a tions,y Vmeans for prime mover for rocking saidcam in opposite directions, and means for Ameans for controlling said cam to thereby adjust the duration of diemeans engaging said Y adjustably determining the limits of .rocking motion of said cam and the speed of rocking of closed and die-opened conditions.

3. A thread rolling machine including a pair of cooperatingl thread rolling dies, means for moving one of said dies toward and from the other comprising a rock shaft having an eccentric portion, a follower for said eccentric porltion operatively connected to said movable die,

the eccentricity of said portion being so angularly arranged as to approach dead center position with respect to said follower when said movable die is nearest to crank for rocking said shaft, a link engaging said crank and movable substantially lengthwise, said crank being substantially perpendicular to said link when said eccentric is near to said dead center position, a -spring bearing at one end on the opposite end of said link, means anchoring the vopposite end of said spring, and link between said: spring and crank and actuable to move said link axially, motion in said spring acting direction to move said movable die the other of said dies.

4. A thread rolling machine including a pair of cooperating thread rolling dies, means for moving one of said dies toward and from the other comprising a rock shaft having an eccentric portion, a follower for said eccentric portion operatively connected to said movable die, the

to rock said eccentric in away from eccentricity of said portion being so angularly L arranged as to approach dead center position with respect to said follower when said movable die is nearest to the other of said dies, a crank for rocking said shaft, a link engaging said crank and movable substantially lengthwise, said crank being substantially perpendicular to said link when said eccentric is near to said dead center position, a spring bearing on the opposite end of said link, and means engaging said link between said spring and crank actuable to move said link axially in direction to store energy in said spring and to move said movable die away from the other of said dies, said engaging means being actuated to free said spring to move said link in the reverse direction and close said moving die toward the other of said dies.

5. A thread rolling machine including a pair of cooperating thread rolling dies, means for moving one of said dies toward and from the other comprising a rock shaft having an eccentric portion, a follower for said eccentric portion operatively connected to said movable die, the eccentricity of said portion being so angularly arranged as to approach dead center position with respect to said follower when said movable die is nearest to the other of said dies, a crank for rocking said shaft, a link engaging said crank and movable substantially lengthwise, said crank being substantially perpendicular to said link when said eccentric is near to said dead center position, a spring bearing on the opposite end of said link, and means engaging said link between said spring and crank actuable to move said link axially in direction to store energy in said spring and to move said movable die away from the other of said dies, said engaging means being actuated to free said spring to move said link in the reverse direction and close said moving die toward the other of said dies, mechanism for actuating said engaging means, a rock the other of said dies, a

of said link in direction to store energy cam having a pair of concentric portions and an interposed inclined portionfor actuating said mechanism, and means for rocking said rock cam alternately in opposite directions. s

6. A thread rolling machine comprising a pair of rotary cylindrical thread rolling dies cooperating to roll threads in a work pieceplaced therebetween, means to rotate said dies in' phased relation, moving mechanism including spring means moving one of said dies toward the other die to cause said dies tov penetrate the work and including cam means actuable to move said one die away from the other die to permit the insertion. of said work blank and to retract and store energy in said spring means, and common means for actuating said rotating means and said moving mechanism. e

'7. A thread rolling machine comprising a pair of rotary cylindrical thread rolling dies cooperating to roll threads in a work piece placed therebetween, means supporting one of said dies for motion toward and from the other of said dies, spring means, operative connections between said movable die and said spring means causing said spring means to press said movable die toward the other of said dies, and power means connected to said connections and actuable to move said movable die away from said other die and simultaneously to store energy in said spring means and operatively connected to said dies to rotate said dies.

8. A thread rolling machine, comprising a pair of cylindrical thread rolling dies cooperating to roll threads in a work piece placed therebetween, reciprocating means connected to said dies for moving said dies toward each other upon forward recprocation to cause said dies to penetrate the work piece and upon backward reciprocation enabling said dies to move from each other to relieve the work piece from said dies and to condition said dies for the next thread rolling operation, power means for rotating said dies and for causing backward reciprocation of said reeiprocating means and dies, and means actuated by said backward reciprocation of said reciprocating means for storing energy and for releasing said energy to cause the forward reciprocation of said reciprocating means and said dies, whereby said power means acts to rotate said dies under the heavy load during the thread rolling operation while the die penetrating power is augmented by said energy storing means and acts to store energy in said storing means when rotating said dies under relatively lighter load between thread rolling operations.

9. A thread rolling machine, comprising a pair of cylindrical thread rolling dies cooperating to roll threads in a work piece placed therebetween, reciprocating means connected to said dies for moving said dies toward each other upon forward reciprocation to cause said dies to penetrate the work piece and upon backward reciprocation enabling said dies to move from each other to relieve the work piece from said dies and to condition said dies for the next thread rolling operation, power means for rotating said dies and for causing backward reciprocation of said reciprocating means and dies, and means actuated by said backward reciprocation of said reciprocating means for storing energy and for releasing said energy to cause the forward reciprocation of said reciprocating means and said dies, whereby said power means acts to rotate said dies under the heavy load during the thread rolling operation While the die penetrating power is augmented by said energy storing means and acts to store energy in said storing means when rotating said dies under relatively lighter load between thread rolling operations, said energy storing means including a spring that is compressed during said backward reciprocation of said reciprocating means.

l0. A thread rolling machine including a pair of cooperating thread rolling dies, means for moving one of said dies toward and from the other comprising a rock shaft having 'an eccentric portion, a follower vfor said eccentric portion operatively connected to said movable die, the eccentricity of said portion being so 'angularly arranged as to approach dead center position with respect to said follower when said movable 'die is nearest to the other of said dies, a. crank for rocking said shaft, a link engaging said crank and movable Vs'ulcs'tantially lengthwise, said crank 1 being Vsubstantii'illy perpendicular to said link when said eccentric is near to `said dead center position a spring bearing on the opposition end l2 of said linkami :means engaging said link between said spring v and crank actuable to Vmove said link axially in direction to store energy in said spring 'and simultaneously to move said movable die away fromjthe other of said dies.

RALPH E- MANDERS- JAMES W. BA'DCHELDER.

REFERENCES CITED The following references are of record in the 'l'e of vthis "patent:

UNITED STATES PATENTS Number Name Date 46,750 crane Mar. 14, 1365 316,0?2 fryleret a1. YApr. 21, 13435 1,150,150 Dowd Nov. "16, 1915 2,257,253 Wemhoneret a1. sept. 3o, 1941 FOREIGN PATENTS

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