US2548841A - Rotary take-up for sewing machines - Google Patents

Description

April 10, 195 1 D. A. GRAESSER ,5

ROTARY TAKE-UP FOR SEWING MACHINES Filed May 12, 1948 4 Sheets-Sheet 1 Jwvawm .Davizi G raesser 4 Sheets-Shet 2 fiaVZ lZJA 671185881! D A GRAESSER ROTARY TAKE-UP FOR SEWING MACHINES April 10, 1951 Flled May 12, 1948 WWW April 1951 D. A. GRAESSER 2,548,841

ROTARY TAKE-UP FOR SEWING MACHINES File d May 12, 1948 v 4 Sheets-Sheet 5 April 1951 D. A. GRAEssER 2,548,841

ROTARY TAKE-UP FOR SEWING MACHINES Filed May 12, 1948 4 Sheets-Sheet 4 Patented Apr. 10, 1951 ROTARY TAKE-UP FOR SEWING MACHINES David A. Graesser, Westfield, N. J., assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application May 12, 1948, Serial No. 26,525

12 Claims.

This invention is concerned with rotary takeup mechanisms for sewing machines. It represents an improvement in dynamically balanced rotary take-ups wherein a single thread-engaging element is cycled in a non-circular orbit at non-uniform angular speeds, thereby to satisfy the thread requirements of a high-speed rotary hook and reciprocating needle without the assistance of supplemental moving thread-engaging elements.

Prior successful attempts to utilize dynamically balanced, rotary take-up motions in lieu of the more conventional, unbalanced reciprocatinglink type have resulted in the use of a plurality of revolving thread-engaging elements which cooperate to answer the thread-handling demands of high speed lock-stitch formation. In this invention, however, a single, revolving thread-engaging element provides the requisite threadhandling movements. Mor specifically, this take-up comprises a means for compounding two uniform, simple rotary motions to yield a single, resultant rotary take-up motion, the orbit of which is non-uniform in its radial displacement, but which is nevertheless dynamically balanced and well suited for high-speed thread-control.

Another feature of the invention is the non- Winding characteristic of the revolving threadengaging element. This is accomplished by rotating the thread-engaging element in a direction opposite to that rotation which is caused by the orbital movement thereof. Thus as the thread-engaging element is revolved and rotated through its orbit, it is also counter-rotated about its center-line in the opposite angular direction, thereby to unwind itself as fast as it winds. The result is zero absolute rotational movement of the thread-engaging element throughout its revolutionary or orbital movement, thus precluding the possibility of unnatural winding of the needle-thread upon the thread-engaging element.

Still another feature of the invention is a timing adjusting mechanism whereb the orbit of the take-up may be shifted relatively to the stitch-forming components of the sewing machine. For example, the point at which the needle-bar is disposed at the bottom of its stroke, or the point at which the needle-thread is pulled between the thread-carrier of the hook and the thread-carrier rotation-restraining finger prior to the setting of the stitch in the work each corresponds to a preestablished point or range of points in the orbital path of the take-up element. By means of the timing adjustment, the threadposed rotary shaft 30, through a pair of bevel handling characteristics of the take-up at those points may be altered by .displacing theorbit angularly relatively to the stitch-forming components of the sewing machine.

Other advantages and features of the take-up will become apparentby referring to the drawings of a preferred embodiment of the invention inwhich: V

Fig. 1 is a longitudinal sectional view'of a sewing machine in which the new take-up mechanism has been incorporated.

Fig. 2 is an end elevational view of the sewing machine, showing the thread-engaging element of the take-up mechanism in full lines and'a portion of the unexposed driving elements in broken lines.

Fig. 3 is an enlarged sectional view of the take-up mechanism taken substantially along the line 33 of Fig. 2.

Fig. 4 is an exploded perspective of the component elements of the take-up. 7

Figs. 5 to 9, inclusive, are diagrammatic views of the head-end of the sewing machine showing five positions of the thread-engaging element of the take-up and the corresponding positions of the rotary hook and needle-bar during on complete stitch forming cycle.

Fig. 10 is a graphical illustration of the unicusped, epitrochoidal path traced by the single thread engaging element ofthe take-up. the formation of one stitch, and showing the five points on the curve correspondingto the positions of the sewing machine elements shown in Figs. 5-9. v

Fig. 11 is a perspective view of the threadcarrier rotation-restraining bar.

The illustrated sewing machine comprises a frame including a bed-portion 20 supporting a vertical standard 2| which carries a horizontal bracket-arm 22. Rotatably journaled in the bracket-arm is an arm-shaft 23 which is externally actuated through a belt driven balancewheel 24 and which reciprocates a needle-bar 25 by means of a crank 26 and connecting link 21. An eye-pointed needle 25' is secured tothe depending end of the needle-bar 25. Slidably journaled in the head adjacent the needle-bar is a spring-depressed presser-bar 28 having a presserfoot 29 aflixed to its depending end. The arm-shaft 23 also drives a vertically disgears 3|. The vertical shaft 30 in turn drives a horizontal rotary hook-shaft 32 through a pair of bevel gears 33, the hook-shaft 32 being disposed at the under side of the bed 20. The two pairs of bevel gears 3| and 33 combine to step up the speed of the hook-shaft to a 2:1 ratio with respect to the arm-shaft. A rotary-hook 34 including a bobbin-case or thread-carrier 34' is secured to the end of the hook-shaft 32 and coooperates with the needle 25 in the formation of lock-stitches. The rotary hook 34 is provided with a loop-seizing beak 8i! and a loop-controlling tail 8|. The thread-carrier 34' of the hook is provided with a notch 83 for accommodating a finger 85 of a rotation-restraining bar 84 mounted on the under side of the bed 26. The finger 85 is fitted loosely in the notch 83 to permit the needle-thread to be passed through the notch once in the formation of each lock-stitch.

A feed-advance eccentric 35 and a feed-lift eccentric 36 are also carried by the arm-shaft 23. Surrounding the respective eccentrics are vertically disposed pitman links 31 and 33 which oscillate rock- shafts 39 and 46 within the bedportion 20 of the sewing machine. Rock-arms 4i and 42 (Fig. 2) are secured to the rock- shafts 39 and 46 respectively and impart the usualiourmotion feeding movements to a feed-bar 43 to which is aflixed a feed-dog 44.

Take-up mechanism Disposed in the head-end of the bracket-arm is the rotary take-up mechanism comprising a single, moving thread-engaging element 45. The take-up is driven by a rotary shaft 46 which is actuated by the arm-shaft 23 through a pair of gears 41 having a 1:1 speed ratio. The shaft 46 is iournaled in a pair of bearings, one comprising an elongated bearing-bushing 48 secured rigidly to the frame of the sewing machine, and the other comprising a short bearing-bushing 49 which is mounted in the frame of the sewing machine for limited turning adjustment. This adjustment is controlled by a vertically disposed adjusting-finger 56 (Fig. 4) which extends upwardly to the top of the head where it joins a, curved plate which is releasably locked to the frame of the sewing machine by a screw 52. The adjusting-finger 56 which is rigidly afhxed to the bearing-bushing 49, may be swung through a limited angular distance governed by the length of a slot 53 in the curved plate 5!. The movement is utilized to effect timing changes in the take-up motion in a manner which is described later in this specification under the heading Timing adjustment of take-up.

Rigidly afiixed to the adjustable bearing-bushing 49 is a sun gear 54 provided with a concentric aperture 55 by means of which the gear is fitted over an extended hub-portion 56 formed integrally with the bearing-bushing 49. The sun gear 54 is rigidly affixed to the face of the bearingbushing 49 and is not free to rotate with the shaft 46.

To the end of the shaft 46 is secured a disk 51, as by brazing. The disk is provided with a bearing 58 adjacent its periphery in which is rotatably journaled a short shaft or hub-portion 59 formed integrally with a planetary gear 60. The disk 51 thus functions as a planet-arm for the planetary gear 60. The sun gear 54 and planetary gear 66 are of equal diameters so that one complete rotation of the arm-shaft 23 causes theplanetary gear 59 to cycle or revolve once about the sun gear 54 and also to rotate twice about its own axis in the same angular direction. The rotary motion of the gear 66 about its own axis is ultimately counteracted or nullified y mechanism hereinafter described.

The hub-portion 59 of the planetary gear 60 is provided with a concentric aperture 6| in which is fitted a shaft 62 carrying a counterbalanced pinion-arm 63. A nut 62 is threaded on the shaft 62 on the opposite side of gear 68 to secure the pinion-arm 63 thereto, and a key 64 and slot 65 prevent relative rotation therebetween. A second shaft or bearing-pin 66 projects outwardly from the pinion-arm 63, and over the pin is fitted the apertured hub or bearing-sleeve 61 of a pinion gear 68.

An internal gear 69 is rigidly seated in a channel 8'2 in the face of the disk 51 by means of a screw 69. The pinion gear 68, which meshes with the internal gear 69, has a pitch diameter equal to one half of that of the internal gear. Thus the pinion gear 68 is caused to rotate twice about its own axis as it cycles or revolves once around in the internal gear. This rotation counters the rotary motion of the planetary gear 60, and establishes zero net rotation in the thread-engaging element 45 in a manner more fully discussed under an ensuing sub-heading Non-winding mechanism. A circular plate or disk 16 is rigidly aflixed to the pinion-arm 63 by means of screws 10 and a pair of mounting pins ll, and the apertured hub of the pinion gear 68 projects through a hole 72 in the face of the disk is. The thread-engaging element 45 is provided with a mounting stud 13 which frictionally engages the apertured hub 63 of the pinion gear 68. A large, circular cover-plate I4 is affixed to the disk 57 by means of screws 14, the coverplate being cut-out to accommodate the small disk 18.

Thread-handling movement of take-up The orbit traced by the thread-engaging element 45 is'a uni-cusped epitrochoid (Fig. 10). The generating elements for the curve are the sun gear 54 and the planetary gear 60, the latter rolling about the periphery of the former and both having equal pitch-diameters. The threadengaging element 45 is carried by the rolling or planetary gear 60. The radial position of the thread-engaging element relatively to the periphery of the planetary gear governs the specific character or shape of the orbit. For example, if the center-line of the thread-engaging element were disposed on the pitch-diameter of the rolling gear, a cardioid curve would be generated. In the instant case, however, the center-line of the thread-engaging element is disposed inside the pitch-diameter, and the orbit consequently differs from a cardioid in that the cusp-portion a (Fig. 10) is flattened and the maximum radial distance of the thread-engaging element from the center of its orbit, occurring at the point e, is decreased.

The take-up is threaded by passing the thread 75 from a thread-guide 76 through a tension device 71 over a check-spring 18, under a slackthread controller 19, up to the thread-engaging element 45 of the take-up, and then down to the needle 25.

The timing of the epitrochoidal orbit of the thread-engaging element relatively to the rotary hook 34 is shown in Figs.5-10 inwhich Fig. 5 is the point at which the needle-bar is disposed at the bottom of its stroke; Fig. 6 is the cast-oil point, or the point at which the thread-loop, after having been carried half-way around the body of the hook is about to be lifted by the action of the take up from the loop-seizing beak 80 onto the 1oop-' controlling tail 8 9 the hook; Fig. 7 is the point at which the thread is being pulled across the rotation restraining notch 83 in the bobbin-case carrier 34' prior to stitch setting; Fig. 8 is a point of completion of stitch setting; and Fig. 9 is the point at which the eye of the needle is re-entering the work to form the next stitch; A detailed description of the process of lock-stitch formation by means of a rotary hook referring particularly to the point at which the thread is being pulled across the rotation-restraining notch in the bobbin-case may be seen in the U. S. patent of C. A. Kessler, No. 2,085,699, dated- June 29, 1937.

The points on the orbit (Fig. 10) of the threadengaging element indicated by letters, a, b, c, d and e, correspond to the points in the stitchforming cycle shown in Figs. 5, 6, 7, 8 and 9, respectively. At the point a the thread-engaging element has reached its point of minimum angular velocity, or the cusp portion of the trochoidal orbit, and vectors in and v2, representing the two velocities which combine to produce the resultant motion of the thread-engaging element, are opposed. The two vectors being almost equal at this point there is a dwell in the take-up motion corresponding to the point at which the needle-bar has reached the bottom of its stroke. Within the next few degrees of rotation of the arm-shaft, the needle-bar bee gins its ascending stroke, slackening the thread which the needle has carried to the under side of the work and thereby forming a loop which is seized by the beak of the hook.

Approaching the point 1) the vectors in and 122 of the take-up combine to develop a resultant motion downwardly toward the hook, giving away thread thereto and permitting the thread loop to be expanded about the hook body. At the point b the loop about the body of the hook has been expanded to its maximum size prior to being pulled from the beak of the hook up onto the tail of the hook. This point in the stitchforming cycle is called cast-01f.

Moving to the point e, the vectors '01 and 122 are both directed upwardly away from the hook to establish the point of maximum absolute velocity of the thread-engaging element. The thread loop about the body of the hook has been rapidly contracted until one of its limbs is worked through the rotation-restraining notch 83 in the bobbin case carrier 34'. It should also be noted that at the point e the vector 222, which varies in magnitude throughout the take-up cycle, has attained its maximum magnitude.

Moving to the point d, the thread-engaging element continues its upward movement, ultimately pulling the thread loop which has just passed about the body of the hook completely clear thereof and then drawing the freed loop, along with the bobbin thread ensnared therein, against the under surface of the work. This is called stitch-setting.

From (1 to e the sum of the vectors yields a steadily decreasing resultant motion in a counterclockwise direction. In this distance the takeup gives up suflicient thread to permit the checkspring 18 to return to its inoperative position and to permit the eye of the needle to carry the thread into the work. From "e to a the take-up gives thread to the needle to permit the latter to move to the bottom of its stroke prior to the formation of a new stitch.

From the preceding description, it should be seen that the two vector motions v1 and m are sotimed that they produce a series of constantly varying resultant motions in the single threadengaging element which enables the take-up to answer precisely the thread requirements of the rotary hook and reciprocating needle without the assistance of supplemental, moving thread-engaging elements, and without producing periods in its thread handling cycle in which there exists uncontrolled slack thread.

Timing adjustment of take-up As indicated in the general description of the take-up mechanism there has been provided a means whereby the timing of the thread-handling movement may be adjusted relatively to the other stitch-forming instrumentalities.

The adjusting finger 50 (Figs.'3 and 4) is connected to the sun gear 54 through the bearing bushing 49, the latter element being free to turn a limited amount in the frame of the sewing machine. By swinging the adjusting finger within the limits governed by the length of the slot 53 in the plate 5| the sun gear may be rotated or turned about its axis independently of the shaft 46. This rotation of the sun gear rotates the planetary gear a corresponding amount.

The planetary gear, however, does not roll'about the periphery of the sun gear during this adjustment as it does in the normal operation of the take-up, but rather turns about a fixed axis. The rotation of the planetary gear carries the thread engaging element either forwardly or backwardly along the line of its orbital motion, with the corresponding positions of the rotary hook 34 and needle-bar 25 remaining unchanged. Thus, for example, the velocity of the thread-engaging element at the time the needle thread is being worked through the rotation-restraining notch in the bobbin-case carrier may be varied.

Non-winding mechanism There has been added to this take-up mechanism, as another important feature of the inventionor take-up cycle. To compensate for this rotary movement which makes unnatural winding of the needle-thread about the threadengaging element possible, it is preferred to counter-rotate the thread-engaging element twice during each cycle. This counter-rotation is '15 ment.

accomplished by means of the internal gear 69 and its meshing pinion gear 68. The internal gear is eccentrically fixed upon the revolving disk 51 coaxially with respect to the planetary gear 60 and the rotary movement of the planetary gear is used to drive the pinion gear around the internal gear; the pinion-arm 63 being the connecting element therebetween. It follows that because the ratio of the pitch diameter of the internal gear to that of the pinion gear is 2:1 the pinion gear will be rotated twice during each take-up cycle. This rotation is passed on to the thread-engaging element to counter or equalize the rotary motion of the thread-engaging element which is inherent in sun and planet move- Having thus set forth-the nature of the inven- -.tion,, what I, claim herein is:

1. In a sewing machine, a reciprocatory threadcarrying needle, a rotary hook complemental to said needle in the formation of lock-stitches,

means for rotating said hook a plurality of times for each reciprocation of said needle, take-up mechanism comprising a single thread-engaging take-up element satisfying stitch-formation thread handling requirements, and driving connections including a rotary shaft for revolving said take-up element about the center of rotation of said shaft at 'a varying radius of revolution and in timed relation with said hook to dispose said take-up element at its point of minimum radius of revolution at substantially the time said needle is disposed-at the point ofreversal of its stroke direction next prior to seizure of the needlethread loop by said hook.

2. In a sewing machine, a reciprocatory thread- -carrying needle, a rotary hook complemental to said needle in the formation of lock-stitches, means for rotating said hook a plurality of times for each reciprocation of said'needle, take-up mechanismcomprising a single thread-engaging take-up element satisfying stitch-formation thread handling requirements, and driving connections including .a rotary shaft for cycling said take-up element in an orbital path at a constantly varyingangular velocity about the center of rotation of said shaft and in timed relation with said hook to dispose said take-up element at its point of minimum angular velocity in said orbit at substantially the time said needle is disposed at the point of reversal of its stroke direction next priorxto seizure of the needle-thread loop by said hook.

3. In a sewing'machine, a reciprocatory threadcarryingneedle, a rotary hook complemental to said needle in the formation of lock-stitches, means for rotating said hook a plurality of times for each reciprocation of said needle, take-up mechanism comprising a single thread-engaging take-up element satisfying stitch-formation thread-handling requirements, and driving connections including a fixed rotary shaft for revolving said take-up element in an orbital path about the center of rotation of said shaft at a constantly varying radius of revolution and angular velocity, said orbital movement being in timed relation with said hook to dispose said take-up element at its point of minimum radius of revolution and minimum angular velocity at substantially the time said needle is disposed 'at the point of reversal of its stroke'direction next prior to seizure of the needle-thread loop bysaid hook.

4. In a sewing machine, stitch-forming mechanism including, a reciprooatory thread-carrying needle, a rotary hook having a needle-thread loop seizing element, a thread-carrier journaled in said hook, a stationary rotation-restraining finger acting to restrict the rotation of said thread-carrier, means for rotating said hook a plurality of times for each reciprocation of the needle, said rotary loop-seizing element cooperating with said needle in the formation of lockstitches by seizing thread-loops cast out from the needle and passing the loops about said threadcarrier, rotary take-up mechanism comprising a single thread-engaging take-up element satisfying the stitch-formation thread handling requirements of said rotary hook and said needle, and driving connections including arotary shaft for revolving the take-u p element about the center of rotation of said shaft at a varying with said hook to. dispose said take-up element at itspoint of maximum radius of revolution at substantially the time the thread-loop from said needle is passing between the thread-:carrier and the rotation-restraining finger in the formation of each stitch.

5. In a sewing machine having a frame, a rotary take-up unit comprising a first shaft mounted in said frame for revolutionary movement about a fixed axis which is parallel to and laterally spaced from the center-line of said first shaft, a second shaft parallel to and laterally spaced from said first shaft, said second shaft being mounted for rotational movement about its own center-line and revolutionary movement about the center-line of said first shaft, driving mechanism for revolving said first shaft, driving mechanism for revolving said second shaft about mounted in said frame for revolutionary movement about a fixed axis of revolution which is parallel to and laterally spaced from the centerline of said first shaft, a second shaft parallel to and laterally spaced from said first shaft, said second shaft beingv mounted for rotational movement about its own center-line and revolution-- ary movement about the center-line of said first shaft, driving mechanism for revolving said first shaft, driving mechanism for simultaneously revolving said second shaft about said first shaft, driving mechanism forsimultaneously rotating the second shaft about-its own center-line in an angular direction countering that of the revolutionary movement of the first shaft, and a thread-engaging element carried, by said second .tary gear, a pinion-arm carried by said planetary gear, a pinion gear mounted on said pinionarm eccentrically of said planetary gear to mesh 7 with said internal gear, anda thread-engaging element carriedby said pinion gear.

8. In a sewing machine having a frame, a rotary take-up unit comprising a rotary shaft journaled in said frame, a sun gear supported by said frame, a planetary gear carried by said shaft to mesh with and roll about the periphery of said sun gear, an internal gear carried by said shaft and disposed concentrically with respect to said planetary gear, a pinion gear carried by said planetary gear eccentrically disposed relatively thereto and meshing with said internal gear, and a thread-engaging element carried by said pinion gear, 7 r

9. In a sewing machine having'a frame; a rotary take-up unit comprising a thread-engaging, element. mounted onsaid frame to'partake e maliees ue r :vi, imp rev ut ry. ne er ments about two centers spaced from each other and spaced from the center-line of said threadengaging element, ancLdriVing connections for rotating the thread-engaging element about its own center-line in an angular direction countering at least one of its simple revolutionary movements.

10. In a lock-stitch sewing machine havinga frame carrying stitch-forming instrumentalities including a reciprocatory needle and a rotary hook, the improvement which consists in a rotary take-up for satisfying the thread requirements of the rotary hook, said take-up comprising a rotary shaft, a bearing-bushing for said shaft mounted in said frame for limited turning movement, an adjusting arm secured to said bushing for turning the bushing in the frame, releasable locking mechanism for fixing the angular position of said bushing relatively to said frame, a sun gear carried by said bushing, a planetary gear carried by said shaft eccentrically thereof to mesh with and roll about said sun gear, and a thread-engaging element carried by the planetary gear.

11. In a lock-stitch sewing machine having a frame carrying stitch-forming instrumentalities driven in timed relationship including a reciprocatory needle and a rotary hook, the improvement which consists in a rotary take-up for satisfying the thread requirements of the needle and rotary hook, said take-up comprising a sun gear mounted in the frame for selective angular displacement relatively thereto, locking mechanism for fixing the selected position of said sun gear relatively to said frame, a planetary gear mounted in said frame to mesh with said sun gear and to partake of combination rotary and revolutionary movement in rolling about the periphery thereof, and a thread-engaging element carried by said planetary gear.

12. In a lock-stitch sewing machine having a frame carrying stitch-forming instrumentalities including a reciprocatory needle and a rotary hook, the improvement which consists in a rotary.

take-up for satisfying the thread requirements of the needle and rotary hook, said take-up comprising a rotary shaft, a bearing-bushing for said shaft mounted in said frame for limited angular displacement, an adjusting arm secured to said bushing for angularly displacing the bushing in the frame, a releasable locking means for fixing the angular position of said bushing relatively to said frame, a sun gear carried by said bushing concentrically with respect to said shaft, a planetary gear carried by said shaft eccentrically thereof to mesh with and roll about the periphery of said sun gear, an internal gear carried by said shaft and disposed concentrically with respect to said planetary gear, a pinion gear carried by said planetary gear eccentrically thereof and meshing with said internal gear, and a thread-engaging take-up element carried by said pinion gear.

' DAVID A. GRAESSER.

REFERENCES CITED UNITED STATES PATENTS Name Date Karle Oct. 19, 1943 Number

Images