US1524327A

US1524327A - Machine for rolling screw threads

Info

Publication number: US1524327A
Application number: US660061A
Authority: US
Inventors: Glenn H Wayne
Original assignee: Scovill Inc
Current assignee: Scovill Inc
Priority date: 1923-08-30
Filing date: 1923-08-30
Publication date: 1925-01-27
Anticipated expiration: 1942-01-27
Also published as: GB221210A; DE438034C; FR585600A

Description

Jan. 27. i925. I 1,524,327

G. H. WAYNE MACHINE FOR ROLLING SCREW THREADS Filed Aug. 30. 1923 2 SheetsSheet 1 M25 W W h l/ 23 W o o f/ ll IIIIH IIIHHHHIII I Iii! I I i lwvewtoz 1524,327 G. H. WAYNE MACHINE FOR ROLLING SCREW THREADS Filed Aug. 30. 192; 2 Sheets-Sheet f2 avwemtoz Patented Jan. 27 1925.

UNITED STATES PATENT OFFICE.

GLENN H. WAYNE, OF WATERBURY. CONNECTICUT, ASSIGNOR 'IO SCOVILL MANU- FACTURING COMPANY, OF WATERBURY, CONNECTICUT, A CORPORATION OF GON- NECTICUT.

MACHINE FOR ROLLING SCREW THREADS.

Application filed August so, 1923. Serial No. 660,061.

To all whom it may concern:

Be it known that I, GLENN H. WAYNE, a citizen of the United States, residing at Waterbury, county of New Haven, and State of Connecticut, have invented certain new and useful Improvements in Machines for Rolling Screw Threads, fully described and represented in the following specification and the accompanying drawings, forming a. part of the same.

This invention relates to machines for rolling screw threads.

In the formation. of screw threads by rolling, a round blank is caused to roll between two threading dies which have relative movement. These dies have complementary series of thread-forming teeth and during the travel of the blank between the dies the metal of the blankis upset into the form of a screw thread.

In the use of thread-rolling machines as heretofore known there has been a considerable loss due to products which have to be rejected because of inaccurate, or what is known commercially as drunk threads.

It is the principal object of the present invention to provide a machine for rolling screw threads such that the threads produced are uniformly accurate within the limits of deviation allowed by trade standards. As is more fully set forth hereinafter, the inaccuracies referred to are due to what may be termed a slippage of the blank with respFctto the dies. It is more particularly an object of the present invention to provide a thread-rolling machine so constructed as to compensate for this slippage and thus produce. more accurate threads.

With this general object in view the invention consists in the combinations, details of construction and arrangements of parts which will first be described in connection with the accompanying drawings and then more particularly pointed out.

In the drawings Figure 1 is a plan view, with parts in section, of a thread-rolling machine constructed in accordance with the invention;

Figure 2 is an enlarged view of part of the same, with parts broken away and in section;

Figure 3 is an end view looking in the direction of the arrow in Fig. 2, with parts in section;

Figure 4 is a sectional view (enlarged) taken on the line 44 of Fig. 2, looking in the direction of the arrow;

Figure 5 is a similar View showing more or less diagrammatically certain of the parts shown in Fig. 4 in a different position;

Figure 6 is a sectional View taken on the line 66 of Fig. 2; and,

Figures 7, 8 and 9 are exaggerated explanatory views of dies and blanks.

Referring to the drawings, the invention in its entirety includes two complementary dies for rolling threads on a blank which rolls between the dies as the thread is formed. The blank may be rolled between the dies by relative movement of the dies and the dies may conveniently be flat blocks, one block being reciprocated with respect to the other. Although capable of various constructions. in that here shown as an example, slidable in upper and lower tracks 11. 12 of a bed block 1?, is a slide 14 having a die-carrying portion 15. This latter carries a flat. substantially rectangular die block 16 which rests on a, ledge 15 of the carrier 15 and is secured in place by means of clamps 17 and bolts 18. The outer ver tical face of this die block has a series of teeth 19, hereinafter referred to. To reciprocate the die 16, as here shown as an example, secured to "he slide 14 is the end of a pitman 20 "driven from a disk 21 by a crank pin 22 mounted therein. Disk 21 is rotatably connected with a gear 23 meshing with a pinion 24 on a drive shaft 25. This shaft is rotated by a pulley 26 to which power may be a plied in any suitable manner. As the drive shaft rotates the slide 14 is moved forward and back in its bed block thereby to cause endwise reciprocation .of the die block.

to have a slight compensating movement,

' means.

hereinafter described,.but as distinguished from the traveling movement of die 16, the second die is stationary. In the exemplific cation here illustrated, carried by a frame or bed block 27 is a supporting block 28 located opposite the slide 14 and adjustably held in position by bolts 29. The block 28 has a ledge 28 on which is supported a die carrier 30 which is held in place by clamps 3i and bolts 32. Mounted in the die carrier 30, in a manner hereinafter described, is a flat, substantially rectangular die block 33 located on a level with the die 16, as appears in Fig. The outer vertical face of the die block 33 is formed with a series of parallel teeth 34 running endwise of the block but at an angle to the longitudinal axis thereof (Fig. 4)- The teeth 19 of die 16 are similarly arranged, the teeth of one die,v

however, being opposed to the intervening grooves of the other, as appears in Figs. 3

and 7.

As will be understood by those skilled in the art, the angle of the die teeth with re- 'spect to the longitudinal axis of the die block; that is, with respect to the direction of travel of the blank, governs the lead of the thread formed on the blank. In the present embodiment the die blocks areso spaced apart that the tooth crests are separated by a distance less than, and the groove bottoms by aidistance greater than, the diameter of that part of the blank that is to be threaded. As a result, the outside diameter of the formed thread is greater than was the diameter of the blank before threading. The embodiment shown is particularly adapted to threading cap screws and with the die relation shown, the blanks have an enlarged stem. so that when threaded. the outside diameter of the threads equals the diameter of the stem.

When the traveling dye 16 is drawn back to the position of Fig. 1. a round blank r is placed between the adjacent ends of the dies by hand or by any suitable feeding Fig. 4t shows a cap screw blank having. its polygonal head above the top edge of the die block, the block having a plain surface 35 corresponding to the stem 36 of the blank that is not to be threaded. Upon the advance movement of die 16, the

blank is rolled between the two dies, that is, the blank revolves on its own axis and travels along between the dies as the travel ing die advances. For a half turn of the blank, the teeth of die 16 form thread portions in half the surface of the blank and the teeth of the die 33 form thread portions in the other half of the blank surface. That is, referring to Fig 9 which represents a section through the blank, die

16 for example, has formed thread portions from the point X around to point Y and die 33, during the same half turn of the around to X. During the next half turn of the blank the half threads formed by the die 16 are presented to die 33 and the half threads formed by the die 33 are presented to die 16 for further formation or finishing or both. Ordinarily the complete thread is roughly formed during the first half turn or first few half turns, the remainder of the action being in the nature of -a finishining or planishing operation. As a result of the die action, by the time the traveling die has 'moved across and beyond the other die. the blank is formed with a com plete finished thread and can drop out from the dies, to be removed in any suitable manner.

While screws have been threaded by rolling blanks between dies in the general manner above described, the threads on rolled screws as heretofore made, have not always been accurate. There has been a considerable loss due to so called drunk? threads which will not enter the standard gauge. These drunk threads are due to a variation from the true or theoretical lead of the thread. In the ideal formation of rolled threads, the blank should start its axial movement and traveling movement, at the same instant and its axial and traveling movements should continue regularly and at the rate for which the dies are designed. It sometimes happens, however. that the start of the axial movement and the-start of the traveling movement are not simultaneous. or the rateof movement is irregular. In other words. there is a certain amount of slippage of the blank with respect to the dies. vAs a result of this slippage. in

machines heretofore known, the lead of the formed thread varies from the theoretical lead because that half of the thread forn'led by one die is out of true position when it moves around to the other die and consequently the teeth of the latter cause the thread to be distorted out oftrue.

Referring to diagrannnatically and in exaggerated manner, the ideal conditions. A represents half of the blank and B represents one die. A

represents the same half of the blank after .die and A the same half of the blank after a half turn. At the right, the broken lines til) Fig. 7, there is shown.

, compensate for slippage of the blank.

. 33 about its pivot, t

indicate the teeth and grooves of the die, the full lines indicating the relative position of the blank after a half turn and upon slippage. That is, formation by tooth b of dieB, when it reaches die C is not inv true mesh with the tooth 0, due to slippage, but has the position (l. The same is true, as will be apparent, of all the grooves and crests. As a result of this out-of-true relation between die and thread, the thread will be distorted by the die C out of its true lead and the finished product will be inaccurate. I

lhe present invention includes means for permitting a die movement transverse the direction of the blanks travel, thereby to may be accomplished for example by so mounting the stationary or non-traveling die that it may float. Although capable of various constructions, in that here shown as' an example, the die block 33 is carried by a bearing plate 40 which is-slidable on the face of the die holder 30. As appears in Fig. 6, the holder 30 has rabbeted top and

bottom ledges

41, 42, by which the plate 40 is confined but enough clearance is left to permit a slight movement of the die. As shown, the die is pivotally mounted, the pivot being adjacent the end of the die at which the blank starts. To this end, secured to the inner face of the plate 40 is a pivot pin 43mounted to swivel in a suitable hole inthe die carrier 30.. The die block and its bearing plate can thus swing about 'pin 43 as a pivot, the slightly curved end of the die block bearing against a roller 44;.

When and if slippage of the blank occurs, and conditions such as described in connection with Fig. 8 exist, the slippage is compensated for b movement of the die moving across the direction of travel of the blank. That is, when the thread of the blank leaving die 16 and approaching die 33 fails to mesh properly with the latter, the strains set up, instead of distorting the thread of the blank to give it an inacits pivot to curate lead, cause the die 33 to swing 011 permit the thread and die teeth to have accurate'registry ormesh. In other words, the die changes its-relative position to compensate for the change in the relative position of the blank, and as a result the thread is not distorted.

With the construction described the threads produced on a succession of blanks are uniformly accurate within the limits of deviation allowed by trade standards.

It is desirable to have the floating die in of therolling normal position at the start of the blank and during the first part of the blank traveL. entirety, therefore, includes means for resettingthedie to normal or initial position,

the groove a, under This e free end of the die 63 by means of a nut 64; is a The invention in its if it has moved, and looking it in such position for a predetermined period with respect to the blank travel. Although capable of various constructions, in that here shown as an example, the end of the bearing plate 40 has a wedge-shaped notch adapted to be entered by a wedge 51. This wedge is formed on the end of a plate 52 slidable in a guide housing 53 on the die carrier 30. On the other end of the plate 52 is an arm 54 through Which passes a rod 55 slidable in an open-sided bracket 56. On the outer end of rod 55 is a nut 57 and between the nut and arm 54 is a coiled spring 58. When the rod 55 is pulled in the direction in which" wedge 51 points (to the left in Figs. 4.and 5), the force of spring 58 causes movement of arm 54, whereby the wedge is moved towardthe notch 50. Upon resistance being encountered by the wedge, spring 58 is compressed until, the coils being closed, nut, spring'and arm move as a unit to force the notch. During this movement, if the die unit, which includes plate 40, has moved out of normal position, the wedge 51 acting against the side ofnotch 50 cams the die unit back to normal position. Further, it will beobserved, as long as the wedge remains in the notch the die unit is locked against movement. This position is shown in Fig. 4.

While the means for actuating the rod 55 may be varied, it may conveniently be accomplished by the movement of the traveling die and may make possible a release of the wedge after a predetermined die travel. constructions, in the present embodiment, secured to the forward end of the die ,carrier 15 is a bracket 60 havingan arm 61 extending toward, die 33 (Figs. 2 and 3). This arm is bent to have its end parallel with and above die 33 and this end 62 is provided with. a slot 63. Set in the slot pin 65 carrying a roller 66. During the idle back stroke of the traveling die, the roller 66 engages an elongated lever 67, fulcrumed on the die carrier 41 and pinned to the end of rod 55. When the wedge 51 is in release position the lever 67 has the position shown in broken lines similarly indicated. As the roller advances to the left it pushes down the lever whereby the rod 55 is given the movement above described and the wedge is forced int-o the .notch 50 to re-set the die if it is moved.

the wedge completely into Although capable of various (Fig. 4), the roller being its lock so as to be able to float as described. To this end, in the exemplification shown,

. there is provided meansfor giving a re- I 70 makes engagement with arm 54: but

thereafter this engagement causes a simultaneous movement of the arm to withdraw wedge 51 from notch 50. During this movement of rod 55, spring 58 is free to re-expand to its former position. A collar 7 0 pinned to rod 55, acts as a stop against bracket 56 to limit the release movement of therod. This position of the parts is shown in Fig. 5, in which, for simplicity of illustration, the teeth of die block 33 have been omitted.

If it is desired to vary the time, with respect tothe travel of the die 16 and blank, at which the die 33 is permitted to float, the pin may be moved along its slot. By this adjustment, the lever 67 will be released earlier or later with respect to the start of the operation, as may be desired.

The. dies here illustrated are for forming right hand threads and the compensating movement of the floating die is upward, that is, toward the head of the blank. The invention in its entirety includes means for preventing a transverse die movement under the force of gravity. This means may conveniently be yieldable upon a predetermined force so that the die may have a compensating movement downward in case die blocks for a left hand thread are used.

Although capable of various constructions, in the embodiment shown, on the bearing plate a0 is a housing 71. In this housing is a plunger 72 each end of which extends through the end ofthe housing (Fig. 4). Coiled about plunger 72 is a spring 73 one end of which bears against the housing, the other end against a collar 74 on the plunger 72. The lower end of plunger 72 in normal position engages the bottom ledge 42 of the die carrier 30. Any tendency of the die block to move down by gravity is resisted by the spring 73. Should there be sufficient force applied, however, to overcome the force of spring 73, the die block can move downward against the compression of the spring. Thus, if left handed threads are being rolled the die can have a compensating movement, in this instance downward.

The operation of the machine shown will be clear from the above without further description.

What I claim is:

1. The combination with two dies for rolling theads on, a blank which rolls between the dies as the thread is formed, of means for ermitting a die movement transverse the irection of travel of the blank, said movement compensating for sli page of the blank with respect to the dies uring the thread forming operation, whereby accuracy in forming the thread is increased, and means for re-setting the die, after such compensating movement, in an initial position.

2. In combination, two dies for rolling threads on a blank which rolls between the dies as the thread is formed, means for moving one of said dies with respect to the other to cause rolling of the blank between the dies, means for mounting the other die to be movable transverse the direction of travel of the blank, and means for re-setting the second die in an initial position after any such transverse movement.

3. In combination, two dies for rolling threads on a blank which rolls between the dies as the thread is formed, means for reciprocating one of said dies with respect to the other to cause rolling of the blank between the dies on the advance stroke, means for mounting the other die to be movable transverse the direction of travel of the blank, and means operated by the movement of the first die on its return stroke for resetting the second die in initial position.

4. In combination, two dies for rolling threads on a blank which rolls between the dies as the thread is formed, and means (a) for permitting a die movement transverse the direction of travel of the blank during a part of the blank movement, said die movement compensating for slippage of the blank with respect tothe dies, and (b) for preventing said die movement during the first part of the travelof the blank.

5. In combination, two dies for rolling threads on a blank which rolls between the dies as the thread is formed, means for causing relative movement between the dies, means for mounting at least one die to be movable transverse the direction of travel of the blank, and'means dependent on the relative position of the two dies for locking the transversely movable die against such movement and for releasing it before the termination of the passage of the blank between the dies.

6. In combination, two dies for rolling threads on a blank which rolls between the dies as the thread is formed, means for movthe blank, locking-.means'for holding the second die against su'ch transverse movement, and means for causing said locking means to release the die after a predetermined travel of the first die.

7, In combination, two dies for rolling threads on a blank which rolls between the dies as the thread is formed, means for reciprocating one die with respect to the other 'to cause the blank, on theadvance stroke, to roll between the dies, the second die being mounted for a die movement transverse the direction of travel of the blank, and means including a part moving with the first die, for (a) resetting thesecond die in initial position upon the idle return stroke of the traveling die, (12) looking the second die in initial position, and (0) releasing the die from its look upon a predetermined travel of the reciprocating die upon its advance stroke.

8. In combination, two dies for rolling threads on a blank which rolls between the dies as the thread is formed, means for reci rocating one die with respect to the ot er to cause the blank, on the advance stroke, to be rolled between the dies, the second die being mounted for a die movement transverse the direction of travel of the blank, and means including a moving with the reciprocating die,-for (a) resetting the second die in initial position u on the idle return stroke of the traveling ie, (6) locking the second die in initial position, and (a) releasing thedie from its look upon ,a predetermined travel of the reciprocating die upon its advance stroke, a part ofsaid resetting, locking and releasing means being adjustable to vary the time with respect to the die travel at which the second die is released.

9. In combination, two dies for rolling threads on a blank which rolls between the dies as the thread is formed, means for causing relative movement between the dies so to cause a blank to berolled between them, means for mounting one die to have a movement transverse the direction of travel of the blank, and means for causing said die to be lockedagainst such transverse movement during a variable portion of the blankrolling relative movement of the dies.

10. In combination, two dies for rolling threads on a blank which rolls between the dies as the thread'is formed, a movable die W carrier for one ofsaid dies, at stationary'die carrier, a die unit comprising the second die mounted in said stationary carrier to have a movement transverse the direction of travel of the blank, said die unit and its I shaped to fit said notch, a lever, an operative carrier having the one a wedge and the other a Wedge-shaped notch, and means for causing relative movement between said Wedge and notch to place the same into and out of'interlocking relation.

11. In combination, two sides for rolling threads on a blank which rolls between the dies as the thread is formed, a movable die carrier for one of said dies, a stationary die carrier, a die unit comprising the second die mounted in said stationary carrier tohave a movement transverse the direction of travel of the blank, said die unit having a Wedge-shaped notch, a wedge shaped to fit said notch and carried by the die carrier, and means for moving the wedge into and out of the notch.

12. In combination, a movable die carrier, a die block mounted therein, a stationary die carrier, a die unit, comprising a second die block, mounted in said stationary die carrier to have a movement transverse the direction of travel of the blank, said die unit having a wedge-shaped notch, a wedge connection between said lever and the wedge, a spring for normally holding said wedge out of the notch, an element moved by the movable die carrier for engaging said lever to cause the wedge to he moved into the notch, and means for moving the movable die carrier to cause a blank to be rolled between the dies.

13. In combination, a movable die carrier, a die block mounted therein, a stationary die carrier, a ,die unit, comprising a die block, mounted in said stationary die carrier to have a movement transverse the direction of travel of the blank, said die unit having a wedge-shaped notch, a ,wedge shaped to fit said notch, a lever, an operative connection between said lever and the wedge, a spring for normally holding said wedge out of the notch, an adjustably positioned element moved by the'movable die carrier for engaging said lever to cause the wedge to be moved into the notch, and means for moving the movable die-carrier to cause a blank to be rolled between the dies.

14. In combination, 'two dies for rolling threads on a blank which rolls between the 115 dies as the thread is formed, means for causing relative movement between the dies to cause a blank to be rolled between them, one die being mounted to be movable transverse the direction of travel of the blank, and means whereby thelast named die may be held against such transverse movement at the start of and during a predeterminable portion of the blank-rolling relative movement of the dies.

In testimony whereof, I have hereunto set n1 hand.

y GLENN H. WAYNE.