US2672774A - Thread rolling apparatus - Google Patents

Description

March 23, 1954 w. STERN THREAD ROLLING APPARATUS 4 Sheets-Sheet. 1

Filed Jan. 25, 1951 INVENTOR. fiz azw/ March 23, 1954 w. STERN 2,672,774

THREAD ROLLING APPARATUS Filed Jan. 25, 1951 4 Sheets-Sheet 2 INVENTOR.

March 23, 1954 w STERN I 2,672,774

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THREAD ROLLING APPARATUS Filed Jan. 25, 1951 4 Sheets-Sheet 4 Patented Mar. 23, 1954 ICE THREAD ROLLING APPARATUS William Stem, Park Ridge, 111., assignor to Illinois Tool Works, Chicago, 111., a corporation of Illinois Application January 25, 1951, Serial No. 207,673

13 Claims. .1

invention relates generally to apparatus for =orming threads on fastener elements and specifically to a machine for rolling threads on screw blanks.

The principal object of this invention is :to provide :a thread rolling machine having a greater capacity, in respect to the number of screw :elements threaded per minute, than any machine heretofore known.

The standard machine for rolling threads on screw :blanks employs a heciprocajting the which on movement in one direction past fixed die, in cooperation with the fused tile, rolls a thread on a screw blank inserted "between the In the forming of the threads, the screw is rotated in the dies through a plurality of revolutions so that the thread wormed is continuous from end to end and is free of burrs and other imperiections. The standard machine produces good threads, is inexpensive, and employs standard sports, but is not entirely saltisraa'itory because of its inherently limited capacity, the heavy parts necessary to withstand the shock of reciprocation, and the incessant vibration.

It has tbeen :proposed heretofore to employ a continuously rotating circular die cooperahle with one or :more acetate dies to overcome the disadvantages of the standard machine. Such thread rolling machines have possessed various shortcomings which have prevented them from coming into commercial usage. These machines have used nonstandard dies, registration of the fixed and moving dies has been dimer-ill; "to obtain, cil culaa' dies have been extremely costly, machines designed to roll screw elements through a plurality of revolutions between circular dies have produced unsatisfactory threals, and satisfactory convergence of the al ies transversely of the dies and in their direction of travel to roll threads on tapered shanks or relatively pointed screws and progressively to work or swage the screw threads has not been obtained.

object of this invention is to elirninate the disadvantages of standard thread rolling machines and of continuously operating thread rollmg machines employing circrilar dies wane possessing the acrvantages of both.

Another object of this invention is to provide a continuously operating thread rolling machine using conventional fiat faced or plane dies.

A further obieot of this invention is to pro-- vide a thread rolling machine simultaneously rolling threads on a 'ialural-ity of blanks.

Another object oi invention is to provide, in a thread milling machine, flexible means for carrying :a plurality of movable (lies and means for firmly supporting the :dies against lateral or transverse movement during the working time of the dies.

Another object of this invention is to provide a continuously operating thread rolling machine wherein the thread ro l-ling mechanism is dosigned to receive screw elements directly from a screw feeding chute.

A more specific object of this invention ls'to provide a thread rolling machine wherein the thread rolling dies receive and support screw elements in the same inclined position in which are fed through an inclined "screw feeding chute.

Another object of this invention is to proville, in a thread rolling machine having a plural'ity of movable dies successively cooperab'le with a fixed die, a control member actuated in timed relation with each movable die to control the movement of screw elements from a screw feeding chute into the space between the fixed and movable dies.

A further olcject of this invention is to provide, a thread rolling machine havinga feed chute a combination gate and. starter member, and a plurality c ffixed and movable dies, means operable accordance with the movable dies to retract the member slowly at first; then to r'e tract the member rapidly to release a screw element and-to hold the member retracted whilethe screw element is moved by gravity from the chute to a movable die; to advance the member rapidly thereafter and iorwardy relative to the movable die to shift the screw element into reg istration with a fixed die; and to advance the member slowly thereafter to insure rolling of the element between the dies.

(other and further objects and advantages or he present invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

Fig. *1 is an end view of a thread rolling machine embodying the principles of my invention;

Fig. '2 is a plan view of the thread rolling machine;

Fig. 3 is a cross sectional view taken along the line :of Fig. 2;

Fig. 4. is a oeta'i-led top view showing the .cooperation of the fixed and movable .dies and screw element supplying mechanism;

Fig. 5 is a side view of one of the movable die blocks;

Fig. 6 is an exploded perspective view of the com mechanism carried by a movable die block;

Fig. '7 is a perspective view showing the screw element supplying mechanism and starter as oooperating with a movable die member;

Fig. 8 is a sectional View showing the mecha nism for actuating the screw element starter;

Fig. 9 is a detail view partially in section showing the adjustment for the starter mechanism; and

Figs. 10-14 are somewhat schematic top views showing the operation of the starter mechanism.

A thread rolling machine embodying the principles of my invention is shown generally in Figs. 1 and 2. The machine includes a stand or base on which is mounted a plurality of brackets 22 having platforms 24. A screw feeding hopper 26 is suitably supported on each of the bracket platforms 24. As will be apparent after studying this disclosure, there may be practically any number of hoppers and supporting brackets. I have illustrated four such hoppers and brackets for purposes of explanation.

The hoppers 26 are identical and each is of the type having a scoop or funnel-like structure 28 for receiving a heterogeneous mass of screw elements. Further structure includes a rotatable drum 3!) which feeds screw elements in succession into a screw feeding chute 32. Each screw feeding chute includes a pair of spaced apart rails for supporting the screw elements by the heads with their shanks depending between the rails. An overhead rail 34 is supported by one or more brackets 36 directly above the space between rails of the chute 32 to prevent screws from popping out of the chute. Suitable mechanisms including clearance wheels 36 are carried with.- in housings 40 and driven by motors 42 to prevent screws not properly positioned in the chutes 32 from being fed down the rails toward the thread rollings dies. A vibrator device (not shown) may be attached to the rails to vibrate the rails and thus assure proper feeding of screw elements down the chutes.

The stand or pedestal 20 further supports a base plate 44 having an upstanding central backup portion 46 (Fig. 3). The ends of the upstanding central portion 46 are arcuately relieved as at 48 (Fig. 2) to provide clearance for a pair of sprocket wheels 50 and 52. The sprocket wheel 50 is secured to a shaft 54 for rotation therewith and is spaced above the plate 44 by means of a hub 56. The shaft extends through the plate 44 and stand or pedestal 2i] and has a worm wheel 58 fixed on its lower end and within a housing 60. A worm is in driving engagement with the worm wheel 58 and is keyed to a shaft 62 extending out of the housing and having a sprocket wheel 64 thereon. The sprocket wheel 64, and hence the sprocket wheel '56, is driven by a sprocket chain 66 engaged with a sprocket wheel 68 of the drive shaft of an electric motor I0.

The sprocket wheel 52 is rotatably mounted on a stub shaft 12 which is mounted in an elongated slot I3 (Fig. 2), to be adjustable toward and away from the sprocket wheel 5a. An endless conveyor I4 including a sprocket chain 76 is passed about the sprocket wheels 50 and 52. For utmost traction and stability the sprocket chain I6 preferably is of considerable height. Such height is readily achieved by utilizing a pair common sprocket chains stacked one on top of the other and secured together by long screws or pins I8 passing through some of the pivotal points of the links of the chains.

A plurality of die blocks 80 is secured on the endless chain I6 by means of the long screws I8. The rear faces of the blocks are recessed at 82 to receive the chain I6 and the screws I8 fit through countersunk apertures 84 in the rear surfaces of the blocks and are threaded into the blocks above the recesses 82. A retainer plate 86 is secured on top of the back-up block 46 by means of bolts 88 and the longitudinal edges of this plate fit within shoulder portions 90 at the upper inner edges of the blocks 86. The plate fit extends substantially from the sprocket wheel shaft 54 to the sprocket wheel shaft I2 and maintains the lower fiat face 92 of each block in firm sliding contact with the upper surface of the base 44 while the blocks move along the straight reaches of the conveyor. A portion of the lower face of each block 68 is arranged at an acute angle relative to the horizontal as at 94. Elongated runner strips 96 which are wedge shaped in cross section are arranged longitudinally of the conveyor reaches and underlie the inclined bottom face portions 94. The runner strips are secured in place by screws 98 fitting through countersunk apertures Iilil in the base or support 44 and threaded into the runner strips 96. The runner strips hold the blocks in firm engagement with the back up block 46 and the retainer plate 86 to prevent lateral and vertical shifting of the blocks while moving along the reaches of the conveyor.

The upper faces I62 are substantially parallel to the inclined lower face portions 94 and upper portions I64 of the blocks are inclined so as to be substantially perpendicular to the top faces. Each outer upper inclined face I04 is provided with a recessed portion I06 and a die I68 having a thread rolling surface I I0 is secured therein by a clamp member H2. The clamp member is substantially in the form of a bridge having depending longitudinal flanges impinging respectively against the top of the die I08 and the upper face I62 of the block 86. The clamping member H2 is secured in clamping position by a bolt or screw I I4 extending through the bridge member and threaded into the upper face of the die block 80. As may be seen in Fig. 5, the dies I08 are shorter than the recesses I06. Set screws [I6 are threaded into the die blocks 80 from the ends thereof and abut the dies to provide for longitudinal positioning thereof and further to secure the dies within the recesses.

A bracket I I8 extends upwardly from the support or pedestal 20 substantially beneath each screw feed chute 32. Each such bracket is 4 provided at its upper end with a recessed portion I20. A stationary die block I22 is carried within each recessed portion I20 and includes a front face I24 substantially parallel to the thread rolling faces III] of the dies I08. Each die block I22 carries a die I26 having a thread rolling surface I28 in opposed face to face spaced relation with the movable dies I08.- Each die block I22 is provided with an arm I30 extending outwardly from the face I24 and positioning the die I26 against the adjacent feed chute 32, a shim I32 being provided between the arm and die for this purpose. Bridge-like clamps I34 similar to the clamps II2 secure the dies in place in the die blocks under the clamping influence of screws I36. In order to provide for adjustment of the movable dies I26 relative to the fixed dies I08, and thus to insure proper registration of the movable and fixed dies, thedie blocks I22 are adjustably secured on the brackets :I I8.

The adjustable mounting of jlthe die blocks,

her I80 allows the next screw element 230!) to fall from the end of the chute against the movable die I081). As the cam follower roller moves along the succeeding steep portion 228 of the cam, the spring I54 pivots the lever I I'I clockwise to shift the gate member to the right, as shown in Fig. 13, at a more rapid rate than the movement of the movable die. As the gate member moves to the right, it pushes the screw element 2301) ahead of it into the space between the stationary die I26 and movable die I081) as they move into opposed position.

Movement of the screw element 2301) into the space between the dies under the impetus of gat member I80 is illustrated in Figs. 13 and 14. When the screw element shank first is engaged by the screw working or thread rolling surfaces of the dies the gate member I80 continues at a decreased rate to push the screw element before it and thus to insure the proper starting of rotation of the screw element between the dies. When the cam follower roller I58 leaves the cam, the gate member I80 reaches the position shown in Fig. and is ready to perform another control operation when engaged by the succeeding cam. I

When no longer acted upon by the gate member I80, screw elements are rolled through a plurality of revolutions by the dies to form threads thereon and then fall from the trailing ends of the fixed dies I26 and die blocks I22 into the enlarged open upper ends 232 of chutes 234 extending beneath the machine to deliver threaded screw elements to a receptacle or other apparatus (not shown). The threaded screw elements generally will fall from the dies into the enlarged chute ends 232 with no difl'iculty, but I prefer to provide air jets 238 positively to preclude any possibility of screw elements being carried beyond the upper chute ends 232 and to the next thread rolling station where they could cause damage to the mechanism.

It is apparent that a machine has been disclosed. herein having a much higher capacity than those heretofore known. The capacity is increased by passing thread rolling dies past one another in opposed face to face relation in only one direction. The relative one way movement allows higher average operating speeds with lower maximum speeds than is possible with the reciprocating thread rolling machines knownheretofore. The capacity further is increased by rolling a screw element between opposed dies each time they pass one another rather than only once for each two passings in the known reciprocating thread rolling machines. The capacity of th machine disclosed herein still further is in creased by the use of a plurality of rolling stations and a plurality of sources of screw elements each of which supplies one of the thread rolling stations.

The specific embodiment of my invention shown and described is for illustrative purposes only. Various changes can be made in the details of construction without departing from the invention as expressed in the following claims.

I claim:

1. A thread rolling machine comprising a movable die unit having a planar thread rolling surface, means for moving said die unit in only one direction over a predetermined closed polygonal path, said path including a rectilinear portion, means along said rectilinear portion of said path for engaging said movable die unit to prevent displacement of said movable die un't transversely of said rectilinear portion of said path, a stationary die unit having a planar thread rolling surface secured adjacent the rectilinear portion of said predetermined path whereby said thread rolling surfaces relatively pass one another periodically in opposed face to face spaced relation, and means for delivering screw elements to the space between said thread rolling surfaces in timed relation with the movement of said movable die unit.

2. A thread rolling machine comprising a first die unit having a planar thread rolling surface, means for moving said first die unit in only one direction over a predetermined closed polygonal path, said path including a rectilinear portion, means along said rectilinear portion of said path for engaging said first die unit to prevent displacement of said first die unit transversely of said rectilinear portion of said path, a second die unit having a planar thread rolling surface adjacent the rectilinear portion of said predetermined path whereby said thread rolling surfaces relatively pass one another periodically in opposed face to face spaced relation, said surfaces being of sufficient extent longitudinally of said path to roll a screw element through a plurality of revolutions, and means for delivering screw elements to the space between said thread rolling surfaces in timed relation with the relative movement of said die units.

3. A thread rolling machine comprising a movable die unit having a thread rolling surface, means for moving said movable die unit in only one direction over a predetermined closed path having straight and curved portions, means along a straight portion for restraining said die unit from movement transversely of said path, a stationary die unit having a thread rolling surface secured adjacent said straight portion of said path whereby said thread rolling surfaces relatively pass one another periodically in substantially parallel opposed face to face spaced relation, means for adjusting the spacing between said thread rolling surfaces, and means for delivering screw elements to the space between said thread rolling surfaces in timed relation with the movement of said movable die unit.

4. A thread rolling machine comprising a movable die unit having a thread rolling surface disposed at an acute angle to the horizontal, means for moving said movable die unit in only one direction over a predetermined closed polygonal path, a stationary die unit having a thread rolling surface disposed substantially parallel to said movable thread rolling surface and secured adjacent said predetermined path whereby said thread rolling surfaces relatively pass one another in succession in the same direction and in opposed face to face substantially uniformly spaced relation, a screw element feeding chute, and means for delivering screw elements inclined at the same angle as said thread rolling surfaces directly from said chute to th space between opposed thread rolling surfaces in timed relation with the movement of said movable die unit.

5. A thread rolling machine comprising an endless belt having two oppositely disposed rectilinear reaches, a plurality of movable die blocks carried by said belt and each having a planar screw working surface, a central block within said belt and backing up said die blocks as they move along said reaches, a plurality of stationary die blocks mounted in spaced relation to said endless belt along said reaches and each having a planar screw workingsurface facing said belt,

means for driving said belt at a uniform constant rate whereby the movable die block working surfaces pass said stationary die block working surfaces successively in opposed face to face spaced relation, means including said central block for supporting each movable die block against movement transversely of said belt as it passes a fixed die block, equal numbers of movable blocks on each reach passing fixed die blocks at the same time to balance out reactions on said central block, and means for introducingscrew elements into the spaces between opposed Working Surfaces in timed relation to the mov ment of, said endless belt.

6. A thread rolling machine comprising a fixed die unit having a screw working surface, means for feeding screw elements along a predetermined path to a terminal point adjacent said fixed unit, a movable die unit having a screw working surface, means for moving said movable die unit past said fixed die unit with said working surfaces in opposed face to face spaced relation, a shiftable member engageable with the shanks of screw elements for controlling movement of screw elements from said terminal point to the space between said working surfaces, and means including means carried by said movable die unit for shifting said shiftable member whereby positively to force the shanks of screw elements into the space between said working surfaces in timed relation to the movement of said movable die unit.

7. A thread rolling machine comprising a fixed die unit having a planar screw element threading surface, a chute for feeding screw elements along a predetermined path to a terminal point adjacent said fixed die unit, a movable die unit having a planar screw element threading surface, means for moving said movable die unit past said fixed die unit with said threading surfaces in opposed face to face spaced relation, 2, reciprocable member engageable with screw element shanks and positioned across said chute at said terminal point for controlling the movement of screw elements from said terminal point to the space between said working surfaces, and means including a cam carried by said movable die unit for reciprocating said reciprocable member whereby to control the movement of screw elements from said chute and to force the shanks of the screw elements into the space between said working surfaces in timed relation to the movement of said movable die unit.

8. A thread rolling machine comprising a fixed die unit having a planar screw element thread rolling surface, a movable die unit having a planar screw element thread rolling surface, means for moving said movable die unit past said fixed die unit with said thread rolling surfaces in opposed face to face spaced relation, a screw element feed chute terminating adjacent said fixed die unit, a gate and starter member engageable with the shanks of screw elements closing the end of said feed chute and reciprocable toward and away from said fixed die unit, lever means for reciprocating said gate, and a cam carried by said movable die unit for actuating said lever to reciprocate said gate and starter member whereby to release screw ele ments from said feed chute and to feed them positively by the shanks into the space between said thread rolling surfaces in timed relation to the movement of said movable die unit.

9. A thread rolling machine comprising a fixed die unit having a planar screw element thread means for feeding l0 rolling surface, means for feeding screw elements along a predetermined path to a terminal point adjacent said fixed die unit, a movable die unit having a planar screw element thread rolling surface, means for moving said movable die unit past said fixed die unit in only one direction with said working surfaces in opposed face to face relation, a shiftable combination gate and starter member normally positioned across said screw element feeding means at said terminal point engage screw element shanks to retain screw elements in said feeding means, means for shifting said gate and starter member in timed relation to the movement of'said movable die unit to release a screw element from said feeding means, and

means for shifting said gate and starter member in timed relation to the movement of said movable die unit to engage the released screw element and shift said released screw element into rolling engagement with said screw working surfaces, both of said shifting means including a cam having a cam surface for retracting said member to release a screw element, a dwell for allowing seating of a screw element in front of said member and a cam surface for shifting said member forwardly to engage the shank of the released screw element to force it into said rolling engagement, both of saidncam surfaces being relatively abrupt adjacent said dwell and being relatively shallow away from said dwell.

10. A thread rolling machine comprising a movable die unit having a planar thread rolling surface, means for moving said die unit in only one direction over a predetermined closed polygonal path, said path including a rectilinear portion, means along said rectilinear portion of said path for engaging said movable die unit to prevent displacement of said movable die unit transversely of said retilinear portion of said path, a stationary die unit having a planar thread rolling surface secured adjacent the rectilinear portion of said predetermined path whereby said thread rolling surfaces relatively pass one another periodically in opposed face to face relation,

screw elements along a predetermined path to a terminal point adjacent said fixed die unit, a shiftable member engageable with the shanks of screw elements for controlling movement of screw elements from said terminal point to the space between said working surfaces, and means including means carried by said movable die unit for shifting said shiftable member in timed relation with the movement of said movable die unit whereby positively to force the shanks of screw elements into the space between said thread rolling surfaces whereby to roll threads on said shanks,

11. A thread rolling machine as set forth in claim 10 wherein the means carried by the movable die unit for shifting the movable member comprises a cam.

12. A thread rolling machine comprising an endless belt having two oppositely disposed rectilinear reaches, a plurality of movable die blocks on said belt and each having a planar screw working surface, a plurality of stationary die blocks mounted in spaced relation to said endless belt along said rectilinear reaches and each having a planar screw working surface facing said belt, means for driving said belt at a uniform constant rate whereby the movable die block working surfaces pass said stationary die block working surfaces successively in opposed face to face spaced relation, means for support ing each movable die block against movement transversely of said belt as it passes a fixed die 'shiftable members engageable with the shanks of screw elements for controlling the movement of screw elements from said terminal points to the spaces between the working surfaces as the movable die blocks pass the fixed die blocks, and means including means carried by said movable die blocks for shifting said shiftable members whereby positively to force the shanks of screw elements into the spaces between said working surfaces in timed relation to the movement of said movable die blocks.

13. A thread rolling machine as set forth in claim 12 wherein the means carried by the movable die blocks comprise cams.

WILLIAM STERN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date McCreary May 18, 1880 Kempster Aug. 28, 1888 Kochendorfer Sept. 18, 1928 Farrell Mar. 5, 1935 Wilcox June 10, 1941 Stem May 13, 1952

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