US2355132A - Thread-rolling tool or appliance - Google Patents

Description

Aug. 8, 1944. T. K. AFFLECK l THREAD-ROLLING TOOL OR APPLIANCE Filed Deo. 30, 1942 Patented Aug. 8,1944

THREAD-ROLLING Tool. R APPLIANCE Theodore King Afileck, London, England, as-

signor to Acton Boet and Fine Threads Limited, London, England, a company of Great Britain Application December 30, 1942, Serial No. 470,653 In Great Britain January 5, 1942 3 Claims.

This invention has reference to tools or appliances for use in the formation of screw-threads on revolving work-pieces, such devices being of the kind comprising a, pair of spaced threaded rolls rotatably mounted in a holder or carrier and adapted to be pressed into rolling contact with the work-peice so as to roll a thread thereon, and the holder being fed forward until the axes of the rolls lie at diametrically opposite sides of the work-piece axis. Since both rolls co-opcrate in the formation of the same thread, it is necessary that they must bear a certain angular relationship to each other to obtain the correct thread form, and the present invention is concerned with providing the necessary means whereby after each operation the rolls are automatically returned to rest in that angular relationship so that they co-operate correctly on making contact With the next work-piece.

It has heretofore been proposed to preserve the correct angular positions of the rolls by means of positive gearing between their spindles, but such an arrangement is impracticable for the reason that both rolls do not retain the same linear velocity in relation to the workpiece during the period of time between the instant when they first make contact with the latter and their arrival at the end of their forward movement when they lie on diametrically opposite sides of the Work-piece, owing to the fact that the forward displacement of the tool as a Whole during the period referred to has the effect of increasing the linear velocity of the workpiece in relation to one roll and decreasing it in relation to the other roll, vso that during such period the rolls are revolving at different speeds.

A thread-rolling device of the said kind, in accordance with the present invention, comprises gearing between one of the rolls and a rotatable member associated with the second roll so that the irst roll and said member rotate at the same speed, a positive driving-connection between said member and said second roll operative when the rolls are in their correct angular relationship for the commencement of a threadrolling operation, means permitting said member to make a restricted angular movement in relation to the second roll suiiicient to accommodate such relative roll-velocity differences as may occur in the circumstances hereinbefore referred to, and a spring-connection between the member and the second roll which serves to return the former to its said initial position relative to the latter on withdrawal of the tool from the workpiece.

The aforesaid member to which the first roll is geared may be loosely rotatable on the spindle of the second roll and the positive driving-connection for said member mayconsists of a pair of inter-engaging abutments respectively fixed to the spindle of the second roll and to the member.

One form of thread-rolling device as constructed in accordance with the invention is illustrated in, and is hereinafter described with reference to, the accompanying drawing, of which Fig. 1 is a side elevation of the tool, Fig. 2 a section thereof taken on the line II-II of Fig. 1, and Fig. 3 a detail section taken on the line III-III of Fig. 2. Figs. 4 and 5 are fragmentary sectional views depicting the relative positions of the thread-rolls and the work-piece as the tool is in the act of being brought into engagement with the work-piece, and at the completion of the forward movement of the tool, respectively.

As will be seen from the drawing, the tool comprises a pair of threaded rolls I0, Il, which are keyed upon spindles I2, I3 rotatably mounted in spaced relationship in a block I4 which is pivotally supported upon the carrier I5. The block I4 is bifurcated to enclose the rolls I0, II between the portions I4I and |42. A spur Wheel I6 is fixed on the spindle I3 of the roll Il and an idler pinion I1 rotating on a fixed pivot I8 upon the block I4 transmits the rotary motion of the spindle I3 to a second spur wheel I9 (of equal pitch diameter with the spur wheel I6) loose upon the spindle I2 of the roll I0. A disc 2U fixed upon the spindle I2 in close juxtaposition to the spur wheel I9 carries on its face fixed stops 2| (Fig. 3) adapted to register with and abut against similar stops 22 fixed to the adjacent face of the spur wheel I9, so that in one direction of rotation of said disc 20 the spur'wheel I9 is driven thereby through the abutment of said stops 2 I 22.

The necessity of permitting the rolls I0, Il to rotate at different speeds during the operation of moving the tool to the position on which the rolls lie on diametrically opposite sides of the workpiece will be better understood by reference to Figs. 4 and 5, in which the work-piece is designated by the reference numeral 23. The directions of rotation of the work-piece 23 and the rolls I0, II are indicated by arrows, as also is the direction of movement of the tool as a whole to perform the thread-rolling operation. It will be evident that during the period of time occupied by forward displacement of the tool as a whole from the position shown in Fig. 4, in which the 2 Y 1 rolls Il. II first make contact with the workpiece 2l. to the position shown in Fig. 5. in which said rolls lie on diametrically opposite sides oi the work-piece, the linear velocity of the work.

in Fig. 5), it is withdrawn as speedily as possible for reasons well understoodl in the art, but during any slight d well which may occur at that position the loose spur wlieel I9 maintains its angular relationship in advance of the disc 20. It will be evident that upon the'withdrawal of the tool the rolls I0, I I will come to rest and in order to ensure that the roll I9 which is associated with the loose spur wheel I9 shall immediately resume its correct angular relationship to the roll Il, a coil spring 24 is arranged with its extremiiies anchored respectively to the disc and the loose spur wheel I9, said spring 2l operating to rotate the loose spur wheel I9 upon its spindle I2 until the stops 22 abut against the stops 2I upon the disc 20, and the parts are thus held in that position until the next operation has commenced and the loose spur wheel I9 again begins to advance upon the disc 20. i i

As in other forms of thread-rolling devices, provision is made for a certain longitudinal movement of the rolls I0, II in relation to the tool holder. In this case spring-pressed abutments are furnished at the ends of the spindles carrying the thread-forming olls; at one end individual springs 25, 2S bear against the extremities of the spindles I2, I9, and at the other end a c'ommon spring strip 21 is mounted upon a support 28 between the spindles I2, I3 with its extremities respectively pressing against a washer 29 contacting the disc 20 and a shoulder 99 on the spindle I9, the arrangement being such that the spindles and rolls are returned to their initial relative longitudinal position after any endwise movement which may have occurred 'during theirollins operation. A

It will be apparent that the invention is applicable to al1 forms of thread-rolling tools of the 5 kind specified, whatever may be, the proportion between the diameters of the thread-forming rolls I and the work-piece.

What I claimI as my invention and desire to secure by Letters Patent is:

l. In a machine for rolling screw threads, in combination, threading rolls rotatable about parallel axes and laterally spaced apart so as to receive between them a work piece to be threaded, and meansv associated with said rolls for main- 15 taining them in a predetermined angular relatlonship when not engaging a work piece, and per` mitting said rolls to rotate relatively to each other when a. work piece is inserted between them, said means including a train oi' intermeshing gears,

'20- and a driving connection between one oi.' said gears and one oi said rolls which prevents relative I rotation of said gear and roll in one direction andpermits restricted relative rotation oi' said gear and roll in the opposite direction.

2. The combination set forth in claim 1 in which said driving connection includes interengaging stops and a resilient elementnormally maintaining said stops in contact but permitting them to separate when one roll is caused to revolve at an 30 angular velocity greater than that of the other.

3. In a machine for rolling Iscrew threads, in combination, a base, parallel spindles rotatably mounted on said base, threading rolls mounted on said spindles, respectively, and positioned to re- 5 ceive between them a work piece to be threaded,

and mechanism connecting said spindles including gears of equal diameter mounted on said spindles. respectively, one gear being ilxed, and the other rotatably mounted, on the associated spindle, an intermedate idler gear with which both of said first mentioned gears mesh, means positively connecting the rotatably mcunted gear to the asso- I ciated spindle for simultaneous rotation in one direction, and resilient means connecting said last mentioned gear to the associated spindle permitting limited angular movement of said gear and spindle in opposite directions.

THEODORE KING AFFLECK.

CERTIFICATE oF CORRECTION. Patent No. 2,555,152. August 8, 191m.

THEODORE KING AFFLECK.

It vis hereby certified that error appears in the above numbered patent requiring correction as follows: In the grantl,lines 2 and 13 respectively, name of assignee, for "Action Boet and Fine IIhreads Limited" read --Acton Bolt and Fine Threads Limited-f; lin the heading to the printed specification, line li, for "Acton Boet and Fine Threads Limited, read -I-Acton Bolt and Fine Threads Limited", as shown by the record of assignments in this office; and that the said Letters' Patent should be readwith this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 26th day of September, A. D. 191114..

Leslie Frazer (S981) Acting Commissioner of Patents.

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