US2968268A

US2968268A - Rotary take-ups for sewing machines

Info

Publication number: US2968268A
Application number: US722989A
Authority: US
Inventors: Arthur Sherman Meloy Jr; William Clayton Van Ness
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1958-03-21
Filing date: 1958-03-21
Publication date: 1961-01-17
Anticipated expiration: 1978-01-17
Also published as: DE1218858B; GB874900A

Description

Jan. 17, 1961 A, s, MELQY, JR" E1- AL 2,968,268

, ROTARY TAKE-UPS FOR sswmc MACHINES Filed March 21, 1958 s Sheets-Sheet 2 INVENTORS Arthur S. Meloy Jr Y William C. Van Ness V f ATTORNEY WITNESS w MMQW F' Jan. 17, 1961 A. s. MELOY, JR., ETAL 2,968,263

ROTARY TAKE-UPS FOR SEWING MACHINES Fil'ed March 21, 1958 :s Sheets-Sheet a THREAD CURVES NEEDLE BAR CRANK ANGLE 0'=BOTTOM DEAD CENTER 225. 210 315 o 45 90 I35 no 225 /F (I I a Q I 9 Fi .3 n 4 v 5- u 7 a Z s n z j f INVENTORS Arthur S. Meloy Jr WITNESS William C. Van Ness 'IURNE Y ROTARY TAKE-UPS FOR SEWING MACHINES Arthur S. Meloy, Jr., Stratford, and William C. Van Ness, Devon, Conn., assignors to The Singer Manufacturing Company, Elizabeth, N .J., a corporation of New Jersey Filed Mar. 21, 1958, Ser. No. 722,989

8 Claims. (Cl. 112-248) This invention relates to a rotary needle thread takeup mechanism for a sewing machine and, more particularly, to a take-up comprising a single thread engaging member which is rotated at constant velocity one revolution for each reciprocation of the needle.

It is an object of this invention to provide a single rotary take-up capable of paying out and drawing in the needle thread in close conformity with the demands of the stitch forming instrumentalities, and capable of maintaining a more accurate control of the thread than has been heretofore possible with a rotary take-up particularly at critical points in the stitch forming cycle, such as needle penetration, loop seizure and withdrawal of the needle thread loop from the loop-taker.

It is another object of this invention to provide a single rotary take-up which in supplying fully the demands of the stitch forming instrumentalities, operates on a smaller loop of thread between the tension device and the needle than has been heretofore possible.

Still another object of this invention is to provide a single rotary take-up device of the above character which is carried on a sewing machine in a simple and effective manner, whereby the take-up may be threaded properly in any position of rotation of the take-up.

Other objects and advantages of this invention will appear from the description hereinbelow of a preferred embodiment as illustrated in the accompanying drawings in which:

Fig. 1 represents an end elevational view of a sewing machine with the take-up guard and bed sectioned to expose the take-up member in the position in which the needle thread loop is being cast off the loop-taker prior to stitch setting,

Fig. 2 represents a vertical cross sectional view of the sewing machineof Fig. 1,

Fig. 3 represents an end elevational view of the bracket arm portion of the sewing machine of Fig. l with the take-up guard removed and showing the position of the take-up at stitch setting,

Fig. 4 represents an end elevational view similar to Fig. 3 but showing the position of the take-up at needle penetration,

Fig. 5 is a perspective view of the take-up element,

Fig. 6 is an exploded perspective view of the base of the take-up element and the means by which it is secured to the needle bar actuating crank pin,

Fig. 7 represents an end elevational view of a portion of the bracket arm of the sewing machine of Fig. 1 with the take-up guard removed and showing the position of the take-up immediately after needle penetration,

Fig. 8 represents an end' elevational view similar to Fig. 7 showing the position of the take-up after loop seizure by the loop-taker,

Fig. 9 represents an end elevational view similar to Fig. 7 showing the position of the take-up atthe start of the take-up action, and

Fig. 10 is a graph illustrating the thread demand of the stitch forming instrumentalities as compared with the thread control attained by the take-up.

The sewing machine to which the take-up of this invention is illustrated as being applied in the drawings is of the type disclosed in the United States patent of Van Wagener et al., No. 2,636,464, April 28, 1953. In the drawings, 10 indicates a bracket arm sewing head of a sewing machine frame which is carried by a standard 11 vertically above a work supporting bed 12. Journaled in the bracket arm and extending into the sewing head 11 is a main shaft 13 to which a counterbalance 14 is fixed. A crank pin 15 secured in the counterbalance is embraced by a driving link 16 which is pivotally connected to a stud 17 secured on a needle bar 18 journaled for vertical reciprocation in the sewing head. A needle 19 clamped on the lower extremity of this needle bar is disposed to penetrate a work fabric on the bed and to cooperate in the formation of lock stitches with a looptaker 20 journaled for turning movement in the bed. A presser bar 21 journaled for vertical movement in the sewing head and spring biased downwardly carries at its lower extremity a presser foot 22 which bears upon a work fabric adjacent the stitching point to control the work fabric during stitching.

As best illustrated in Fig. 6, a flanged free extremity 23 of the needle bar actuating crank pin 15 is formed on its face with a raised arcuate rib 24 having its center of curvature coincident with the axis of rotation of the main shaft 13. A circular plate 25 having a counterweight 26 attached thereto is formed with an arcuate slot 27 having a center of curvature equal to that of the arcuate rib 24 and located coincident with the center of said circular plate. The slot 27 of the circular plate is disposed to embrace the rib 24 on the crank pin and the circular plate is clamped thereon with a small range of angular adjustment between the flanged crank pin extremity 23 and the base portion 28 of a take-up member, indicated generally as 29. The take-up member is secured in place by fastening screws 39 which are threaded into the raised rib 24 of the crank pin.

The free extremity of the sewing head 11 is closed by a flat planar end cover plate 30 secured by screws 31 to the sewing head and formed with a circular opening 32 to accommodate the circular plate 25. As illustrated in Fig. 2, the circular plate 25 is preferably arranged substantially flush with the outside surface of the end cover plate 30. Secured to the end cover plate beneath the take-up member, as by fastening screws 33, is the bridge piece 34 of a take-up guard member 35 which extends upwardly from the bridge piece in spaced relation to the end cover plate to define therebetween a thread receiving slot 36.

The base portion 28 of the take-up member is flat and of substantially semicircular outline so as to seat flush against the circular plate 25. From the chord portion of the semicircular outline of the base portion, projects an arm 40 which extends generally radially outward from the base portion and is offset outwardly in spaced relation to the circular plate 25 when the take-up member is secured thereon. The arm 40 is narrower than the base portion 28 of the take-up, thus providing

ears

41 and 42 on the base member, one at each side of the arm 40. The ears are each turned inwardly so as to extend through the circular opening 32 of the end cover plate 30 and thus to extend inside the planar outer surface defined thereby, the ear 41 entering an aperture '43 in the circular plate 25 and the ear 42 entering a notch 44 formed along the periphery of the plate.

The arm 40 of the take-up member at its outer extremity is bent slightly inwardly toward the end cover plate 30 and terminates in a sharply outturned thread retainer 45 formed with

bowed fingers

46 and 47 extending one on each side of the arm 40, the

fingers

46 and 47 conforming generally to the arc of a circle having its center substantially coincident with the axis of rotation of the take-up.

The needle thread, as is illustrated in all of the end elevational views of the sewing machine bracket arm head in the drawings, extends in a single loop around the arm 40 of the take-up member, and the take-up action is derived as the thread loop travels back'and forth along the arm 40 during rotation of the take-up member as will be explained in detail hereinafter. The thread loop is maintained on the arm 40 by means of the thread retainer 45 and the bowed fingers 46 which hold the thread loop from falling off the free extremity of the arm 40 and by means of the inturned

cars

41 and 42 which act to prevent the thread loop from being pulled or wedged in between the take-up base portion 28 and the circular plate 25.

One advantageous feature of the above described takeup construction and mounting arrangement is that the take-up cannot be threaded improperly in any angular position. When the free extremity of the take-up member extends vertically upwardly, as in the position of the take-up illustrated in Figs. 3, 4 or 7, the thread as it is directed into the thread receiving slot 36 will fall behind the arm 40 and over the inturned cars which is the same position that the thread loop will occupy in this position of the take-up during sewing. When the free extremity of the take-up extends downwardly, as in Figs. 2, 8 or 9, the thread will fall over the arm 40 and behind the bowed fingers 46 of the thread retainer which is also the proper position for the thread loop during sewing operations.

In threading the take-up, the thread is first directed from a supply through a tension device 50, over a check spring 51 and around a thread guide 52 which is preferably fixed on the presser bar 21. The thread leading from the take-up is directed through a thread guiding eyelet 53 on the end cover plate 30, through a thread guide 54 on a needle bar bushing 55 and then to the eye of the needle.

As the take-up member is rotated in the direction of the arrow in the drawings, the thread loop between the

guides

52 and 53 is taken up and payed out along the arm 40 of the take-up member. As the thread loop is expanded and during the initial stages of the subsequent slackening thereof, the leading edge 60 of the take-up arm 40 is in engagement with the thread. The leading edge 60, which extends outwardly from a throat 61 defined by the juncture of the arm 40 with the inturned car 42 and terminates in a throat 62 defined by the juncture of the arm 40 with the curved arm 47 of the thread retainer 45, thus provides a thread controlling cam surface for taking up the thread, setting the stitch, and controlling the initial stages of thread slackening in preparation for the succeeding stitch. Similarly, the trailing edge 70 of the take-up arm 40 is in engagement with the thread loop during the remainder of the thread slackening portion of the thread controlling cycle and thus serves to control the paying out of the thread loop as the looper seizes the needle thread and carries it about the bobbin thread mass. The trailing edge 70 of the take-up arm 40 extends outwardly from a throat 7i defined at the juncture of the arm 40 with the inturned ear 41 and terminates in a throat 72 defined by the juncture of the arm 40 with the curved arm 46 of the thread retainer 45.

Rotary take-ups present a problem of thread winding in the event that the needle thread should break at or near the needle. In the absence of any provision against this contingency, a large amount of thread could be wound onto the take-up in a very few cycles of rotation which, in addition to wasting a great deal of thread, could seriously jam and damage the take-up. A knife blade is provided on the end cover plate 30 behind the take-up and an auxiliary knife 81 on the take-up guard 35 both knives being positioned out of the path of the thread loop on the take-up during normal operations when the thread is unbroken. It is also known in the art to form the take-up member so as to encourage winding, if it should occur, to take place at the outer extremity of the take-up arm so as to carry the thread being wound on the take-up into engagement with the knife. Moreover, it has been known in the art to taper the thread engaging arm of a single rotary take up so that its edges converge toward the thread retainer at its free extremity to prevent the wound loops of thread from slipping inwardly out of range of the knife. In prior take-ups, however, the taper was made to continue over the entire length of the thread engaging arm.

In the present invention, it has been found that such an outwardly extending converging portion need only extend over a relatively short outer portion of the takeup arm and that with this construction the thread will be wound at the free end of the take-up arm just as effectively as if the taper had occurred over the entire arm.

As a result of this discovery, the leading and trailing edges 69 and 70 of the take-up arm may be formed in a different and more advantageous manner than had been heretofore possible when the continuous taper was believed to be necessary. As illustrated in the drawings, the outer portion of the leading edge 69 of the take-up arm is formed with a continuous curve starting at the outer throat 62, extending inwardly substantially coincident with a radial line xx on the take-up member, see Fig. 3, and then curving in the direction of rotation of the take-up member to a point slightly beyond that of tangency with an imaginary circle having its center coincident with the center of rotation of the take-up member. The curved outer portion of the leading edge 60 thus provides a concave shape in the direction of rotation of the take-up which terminates at its inner extremity in a shoulder 64 protruding in the direction of rotation from which shoulder to the inner thread eonfining throat 61 the leading edge 60 extends in a substantially straight line which is inclined inwardly.

The trailing edge 70 of the take-up arm is formed with a substantially straight outer portion which diverges from the leading edge 60 from the outer thread confining throat 72 to a shoulder 74 which projects from the trailing edge 70 in a direction opposite that of the rotation of the take-up member. From the shoulder 74 to the inner thread confining throat 71, the trailing edge 70 is formed in a continuous curve inclined in the direction of rotation of the take-up member from the shoulder 74 to a point substantially coincident with the radial line xx illustrated in Fig. 3, and then merging with the ear 41 to define the inner throat 71.

In discussing the action on a thread of the take-up of this invention, reference will be had to the thread curves in Fig. 10. In Fig. 10, illustrated in a heavy solid line labeled Take-Up, is a curve indicating the amounts of thread made available to the stitch forming instrumentalities by the take-up at the various angular positions of the take-up member; the point marked A being that illustrated in Fig. 3 at which the stitch is being set and at which there will be no thread available for the needle and loop-taker. The light solid line in Fig. 10 labeled Needle and Loop-taker Demand indicates the minimum thread demands of the needle and the loop-taker. The demand curve may be said to represent static demand since it was obtained by stopping the machine at successive points and measuring the actual minimum demands and, therefore, does not include the demands which might arise due to inertia forces on the thread during high speed operation. The dashed line curve labeled slack indicates the reserve or loose thread provided by the take-up over and above the absolute minimum required by the stitch forming instrumentalities.

As indicated at point E in Fig. 10, the take-up member in the position illustrated in Fig. 9 is beginning to take-up the thread from the stitch forming instrumentalities. At this point the loop-taker will have carried the needle thread loop around the bobbin thread mass and the thread must be drawn off the loop-taker. The thread, when first engaged by the take-up, will be confined at the outer extremity of the take-up arm 40 by the thread retainer 45 and will extend across the

outer throats

62 and 72 thereof. Referring to Fig. 1, which illustrates the take-up position at point P on the curve of Fig. 10, the take-up action is progressing and the thread is cast off the loop-taker. The thread will now be controlled solely by the leading edge 60 of the take-up arm. As illustrated in Fig. l, the thread loop will slip rather quickly down the curved outer portion of the leading edge 60 toward the point thereon which curves tangent to a circle having its center at the axis of turning movement of the take-up member. Fig. 3 which illustrates the position of parts at stitch setting point indicated at A in Fig. 10, shows that the thread loop will be disposed at the point of tangency at stitch setting time. The continuation of the curve slightly beyond tangency will prevent the thread loop from sliding further and will thus provide a definite stitch setting point on the take-up.

Fig. 3 also illustrates that the thread loop at stitch setting will have moved a considerable distance along the leading edge 60 toward the center of rotation of the take-up member. At stitch setting position the maximum loop of thread will be drawn up by the take-up, and by locating the definite stitch setting point nearer the center of rotation than was possible with previous take'ups, the construction of this invention provides for a smaller total length of thread between the tension device 50 and the needle, thereby reducing the total stretch which can occur in the thread and consequently providing a maximum of accurate control of the thread.

Immediately after stitch setting when the needle descends to penetrate the work in the succeeding stitch forming cycle, the control of the needle thread is extremely critical. The thread at the time in the cycle must be slackened to provide for the needle movement, but if 'slackened excessively, an uncontrolled loop of thread can form between the needle and the work which loop can be entered by the needle to cause thread breakage. Heretofore, in rotary take-ups, the thread was slackened excessively after stitch setting and the check spring 51 was expected to provide a momentary control on the thread in order to prevent the formation of an abnormally large thread loop. In the present invention, the shoulder 64 on the leading edge 60 serves, as illustrated in Fig. 4, as a thread detaining means, that is, as a means for positively detaining the thread from movement along the leading edge 60 so as to retain control of the thread after stitch setting so as to provide a controlled slackening of the thread until after needle penetration has occurred. As illustrated in the thread curve of Fig. 10, needle penetration is complete at point B, following which the thread loop drops over the shoulder 64 to the position as illustrated in Fig. 7 and corresponding to point C on the thread curves so as to supply the additional slack thread necessary for the needle to present a loop to the loop-taker.

At point D on the thread curve, the loop-taker has entered the needle thread loop and is in the process of expanding the loop about the bobbin thread mass of the loop-taker. It is common in prior rotary take-ups that at this point in the cycle all control of the needle thread loop by the take-up is lost and for the threadwhen considerable inertia forces are active on the thread, such uncontrolled loops are subject to snagging or movement into abnormal positions from which recovery may impose excessive strain upon the thread with consequent thread breakage. As illustrated in Fig. 8, the curved inner portion of the trailing edge 70 of the take-up member and the shoulder '74 wh.ch are made possible because of the discovery that the take-up arm need not be tapered continuously over its entire length, serve as a thread detaining means, that is, as a means for positively detaining the thread from movement along the trailing edge 70 so as to retain the thread-loop on the take-up arm as the loop of thread is payed out by the take-up, Control of the thread-loop by the take-up is not lost, therefore, and the thread-loop is accurately metered out by the take-up until the loop finally falls over the shoulder 74 and onto the thread retainer 45, at which time the take-up cycle begins to repeat almost immediately with the take-up again drawing in thread as illustrated in Fig. 9.

This invention thus provides a take-up capable of maintaining heretofore unattainably accurate control of the thread during all phases of the stitch forming cycle. This take-up, furthermore, can be threaded in any angular position and operates with a smaller loop of thread than has been heretofore possible with known take-up constructions.

Having thus described the nature of the invention, What we claim herein is:

1. A rotary take-up for a sewing machine having a pair of thread guides, said take-up adapted to act on a thread extending between said thread guides and comprising, a rotary take-up member, means for rotating said take-up member continuously in one direction about a predetermined axis of rotation, said take-up member including a base portion and an arm extending outwardly with respect to the axis of rotation of sad take-up member from said base portion, said arm providing a leading edge facing in the direction of rotation of the take-up member along which leading edge the thread can slide as it is being drawn up by the take-up, and a trailing edge facing in the direction opposite that of the direction of rotation of the take-up member along which trailing edge the thread can slide as it is being given up by the take-up, means at the free extremity of said arm defining concave outer thread confining throats on the leading and trailing edges of said arm, means at the juncture of said arm and said base portion defining concave inner thread confining throats on the leading and trailing edges of said arm, convex thread detaining means formed on only the inner half of the leading edge between said inner and outer throats, and convex thread detaining means formed on only the outer half of the trailing edge between said inner and outer throats.

2. A rotary takeup as set forth in claim 1, in which the thread detaining means on both the leading and trailing edges comprise shoulders formed on said edges, the shoulder on said leading edge extending outwardly substantially in the direction of rotation of said take-up member and the shoulder on said trailing edge extending outwardly in a direction opposite that of the direction of rotation of the take-up member.

3. In a sewing machine having a frame, a shaft rotatably journaled in said frame and a pair of thread guides carried by said frame, a take-up comprising a take-up member including a base portion and an arm extending outwardly from said base portion, means for securing the base portion of said take-up member to said rotary shaft for rotation of said take-up member therewith, the arm of said take-up member providing a leading edge facing in the direction of rotation of the take-up member along which leading edge the thread can slide as it is being drawn up by the take-up, and a trailingv edge facing in the direction opposite that of the direction of rotation of the take-up member along which.

trailing edge the thread can slide as it is being given up by the take-up, means at the free extremity of said arm defining outer thread confining throats on the leading and trailing edges of said arm, means at the juncture of said arm and said base portion defining inner thread confining throats on edges of said arm, a thread detaining shoulder formed on the trailing edge of said arm and extending outwardly in a direction opposite that of the direction of rotation of the take-up member, and a knife blade carried by said sewing machine frame having a sharpened edge disposed within axial projection of the path of motion of said thread detaining shoulder and facing in a direction opposite that of the direction of rotation of the take-up member.

4. A device as set forth in claim 3, in which the width of the arm of the take-up member from the leading edge to the trailing edge decreases from the thread detaining shoulder on said trailing edge to said outer thread confining throats.

5. A device as set forth in claim 3, in which the width of the arm of the take-up member from the leading edge to the trailing edge decreases from the thread detaining shoulder on said trailing edge to said outer thread confining throats, and also decreases from said thread detaining shoulder on said tra ling edge for at least a portion of the distance from said thread detaining shoulder to said inner thread confining throats.

6. A rotary take-up for a sewing machine having a pair of thread guides, said take-up adapted to act on a thread extending between said thread guides and comprising, a rotary take-up member, means for rotating said take-up member continuously in one direction about a predetermined axis of rotation, said take-up member including a base portion and an arm extending outwardly with respect to the axis of rotation of said take-up member from said base portion, said arm providing a leading edge facing in the direction of rotation of the take-up member along which leading edge the thread can slide as it is being drawn up by the take-up, and a trailing edge facing in the direction opposite that of the direction of rotation of the take-up member along which trailing edge the thread can slide as it is being given up by the take-up, means at the free extremity of said arm defining concave outer thread confining throats on the leading and trailing edges of said arm, means at the juncture of said arm and said base portion defining concave inner thread confining throats on the leading and trailing edges of said arm, convex thread detaining projections formed on the leading and trailing edges of said arm between said inner and outer concave thread confining throats, said leading edge of the take-up arm extending from said outer thread confining throat being formed With a curved portion extending substantially radially inwardly adjacent said outer thread confining throat and curving gradually in the direction of rotation of said take-up member through and beyond the point of tangency with a circle having its center coincident with the axis of rotation of said take-up memher, said curved portion of said leading edge terminating at said thread detaining projection on said leading edge and said trailing edge extending from said inner thread confining throat substantially radially outwardly and curving gradually in a direction opposite to the direction of rotation of said take-up member, said curved portion of said trailing edge terminating at said thread detaining projection on said trailing edge.

7. A rotary take-up as set forth in claim 6, in which the curved portion of said leading edge adjacent the outer thread confining throat and the curved portion of the trailing edge adjacent the inner thread confining throat each extends substantially coincident with the same radial line on said take-up member.

8. In a sewing machine having a hollow frame including a portion defining a planar outer surface formed with an aperture, a shaft journaled in said frame on an axis normal to said planar frame surface and a rotary take-up member including a base portion and an arm extending outwardly from said base portion and defining a leading edge and a trailing edge along which edges a thread can slide, means extending through said aperture for securing the base portion of said take-up member to said shaft with said take-up arm disposed outside said planar outer surface, means at the free extremity of said take-up arm defining outer thread confining throats on the leading and trailing edges of said arm, and a pair of fingers formed on the base portion of said take-up member, one finger at the juncture of the leading edge of said take-up arm with said base portion and the other at the juncture of the trailing edge of said take-up arm with said base portion, said fingers being inturned and disposed to extend into said frame aperture and inside said planar outer surface to define inner thread confining throats on the leading and trailing edges of said take-up arm.

References (Cited in the file of this patent UNITED STATES PATENTS