US2025754A - Thread take-up for sewing machines - Google Patents

Description

P. KUHLIG THREAD TAKE-UP FOR SEWING MACHINES y Dec. 31, 1935.

Filed Deo. 9, 1932 2 sheets-sheet 1 Dec. 31, 1935. R @HUG 2,025,754

THREAD TAKE-UP FOR SEWING MACHINES Fl ed Dec. 9, 1952 2 Sheets-Sheet 2 i 1|* Cb Patented Dec. 31, 1935 UNITED STATES THREAD TAKE-UP AFOR, ySEWINGv MACHINES Paul Kuhlig, Kenmore, N. Y., assignor to Consolidated Packaging Machinery Corp., Buialo, N. Y., a corporation of New York Application December 9, 1932, Serial No. 646,436

4 Claims.

This invention relates to a thread take-up for sewing machines and is shown as embodied in a sewing machine which sews an interlocking two thread chain stitch, although the present invention can be used in connection with any type of sewing machine where it is desirable to take up the slack in the thread resulting from the reciprocation of the needle and to restrict the size of the loop formed by the needle so that, when running at very high speeds this loop is always caught by the looper and the stitch always completed.

One of the principal objects of the present invention is to provide a. thread take-up between the tension adjusting device and the reciprocating needle holder of a sewing machine which takeup device engages and releases the thread being fed to the needle holder as the needle holder reciprocates and in so engaging the thread moves the thread in such manner as to take up all slack in this thread resulting from the reciprocation of the needle holder in sewing; draws the loop made by the needle to a small size so that it is always caught by the looper and is never lost; allows a small amount of slack at the start ofthe forward Stroke of the needle holder so as to ,provide adequate thread for the formation of the loop; and on the retraction of the needle holder pulls upon the thread so as to tighten the stitch.

Aiurther object of the present invention is to provide such a take-up device which is readily adjustable to provide the exact size of loop desired, this being effected by adjustably moving the take-up device toward and from the work being operated upon.

A further purpose of the present invention is to provide such a thread take-up which is extremely simple in construction, can be readily adjusted and which, under all conditions of operation, particularly at very high speeds of the sewing machine, takes up and feeds out the slack in the needle thread each time the needle is reciprocated toward and from the material being sewn, thereby avoiding all danger of breaking or snarling the thread as well as restricting the size of the loop so as to always be caught by the looper and drawing upon the needle thread when the stitch is completed so as to tighten the stitch.

Another purpose is to provide such a device which is extremely compact and inexpensive and which is fitted in place of the usual thread guide or eye of a standard machine, thereby enabling thetake-up device to be applied to standard machines as now constructed by removing the thread guide and substituting the present take-up.

In the accompanying drawings:

Fig. 1 is a front elevation of a sewing lmachine equipped with my thread take-up.

Fig. f2 is an end 4elevation of the same.

Fig. 3 is -a horizontal fragmentary sectiontaken on line 3 3, Fig. 1. i 5

Fig. 4 is a perspective View of the thread takeup embodying the present invention and detached from the sewing machine.

Figs. 5-10 are fragmentary horizontal sections similar-to Fig. 3 and showing progressively the l0 operation of the take-up as the needle is reciprocated back and forth in sewing a doublethread interlocking chain stitch.

The take-up forming the subject of the present invention is designed primarily for use in a Asew- 15 ing machine in which the needle is carried by a needle holder and is reciprocated through `the material being sewn, the needle, onbeing projected forwardly, entering the triangle formed between a previously formed loop and the looper 20 thread, and on retracting forming a loop which is caught by the looper and'held` untilthe needle is again reciprocated forwardly. In operating such machines at high speeds, vand particularly with twine .the loop formed by the needle while 25 retracting tends either to forni' on both sides of the needle, or if formed on only one side-of the needle, is excessively large so that it frequently drops down, is notcaught bythe looper and a failure in stitching results. Moreover, in machines 30 operating at high speeds` without a take-up device there is a tendency for the needle thread to be broken and snarl and no adequate provision is made for drawing the stitch tight after it is formed. -The present take-up vis designed to 35 overcome these diiiiculties and in its general organization consists of a stationary cam plate around which the needle thread between lthe tension adjusting `device and the needle holder is drawn back and forth as the needle holder re40 ciprocates, this cam plate being so designed that as the needle holder reciprocates back and forth a loop or lateral deection is formed in the .thread and then paid out, thereby taking up the slack in the thread. The cam plate is also so shaped that it adjustably imposes tension u pon the needle thread as the needle holder retracts, thereby decreasing the lnormal size of the loop formed 'by the needle and insuring its being reliably ,caught v by the looper. This tension is .continued so as to Adraw the stitch tight and at the end of the retracting movement of the needle the thread is released by the cam plate so as to kprovide valimited slack -in the thread and thereby provide'55 enough thread for the proper formation of the next succeeding loop.

The sewing machine in connection with which my invention can be used, can be of any usual and well known form, that shown in the accompanying drawings being a sewing machine which sews a chain stitch with an interlocking thread. The sewing machine is adapted for sewing any kind of material but is particularly adapted for sewing at high speeds and for sewing with twine or other relatively coarse sewing materials.

Inasmuch as the general features of the sewing machine shown in the accompanying drawings are old and well known, a detailed description is deemed unnecessary except as affecting the take-up device forming the subject of the present invention. The operating parts of the sewing machine are shown as carried by a stationary frame I2 carrying a horizontal crank shaft I3 which is driven by a pulley I4, this crank shaft having the usual fly wheel I5. The end of the crank shaft I3 adjacent the needle is formed to provide a crank i6 which reciprocates a connecting rod ITI, the lower end of which is connected to one arm I8 of a bell crank lever I9. This bell crank lever is pivoted, as at 20, to the machine frame I2 and its other arm 2| is connected by a link 22 with the horizontal reciprocating rod or needle holder 23 which carries the needle 24. The needle 24 is removably secured to the end of the reciprocating rod or needle holder 23 in any usual and well known manner and the rod 23 is guided for horizontal reciprocating movement in a pair of slideways 25 and 26. Each of these slideways is suitably mounted on the machine frame I2 and carries an eye 2l, which receives the needle thread 28. This needle thread is fed from a suitable spool (not shown) through a tension adjusting device 29 and through a tubular guide 35, the lower end of which is disposed immediately above the axis of the reciprocating needle rod 23. From the lower end of the tubular guide 35 the thread 28 passes through an eye 3| in the rear end of the reciprocating -needle rod 23, thence through the eyes 21 and thence through the eye in the point of the needle.

It is apparent that, in the absence of provision to prevent it, each time the needle rod 23 is retracted, slack would occur in the thread 28, the

Li: present invention being designed to take up this slack as hereinafter explained. It is also apparent that in the absence of provision to prevent it there is nothing denitely limiting the size or form of the loop formed by the needle, this being generally determined only by the amount of thread withdrawn from the tension device at the end of the return stroke of the needle holder. Moreover, it is also apparent that there is nothing other than the resistance of the tension adjusting )device for tightening the stitch after it has been The sewing machine is provided with the usual presser foot 32 which is yieldingly held against the side of the material being stitched by a spring The sewing machine is also provided with the usual thread cut oif which is driven from the pulley 35 on the crank shaft I3 by means of a belt 36 which passes around another pulley 31.

The looper 38 is carried at one end of `a horizontal arm 39 which is xedly clamped to theY lower end of a connecting rod 40. Theupper end of this connecting rod 4) is secured to the crank 4| on the crank shaft I3 andthe connecting rod is guided, intermediate its ends, by a pivoted iblock 42, this block being Divoted, as at 43, so

that it is free to turn about a horizontal axis, lengthwise of the crank shaft I3. As an auxiliary means for turning the block and avoiding wear between the connecting rod 40 and the swinging block 42, a leaf spring is also preferably secured 5 to the side of the connecting rod 46 and bears against one side of the block 42. The thread 44 to the looper can be fed in any suitable manner. The mounting 0f the looper 38 in this manner gives the required vertical movement to enter 10 the loop formed by the backward movement of the needle and also gives it the necessary horizontal movement for drawing this loop along the stitch line and for forming the triangle which is entered by the needle on the next succeeding forl5 Ward stroke.

" The sewing machine shown, is provided with the usual feed mechanism which consists of a feed dog (not shown) which is carried at the lower end of a vertical lever 54. This vertical lever 54 20 is pivoted at its center, as indicated at 55, so that it has both lateral and fore and aft movement and at its top this lever 54 is guided in its movement by an eccentric 55 and a cam block 59 having a cam groove 5l'. The eccentric 55 and the 25 groove 5l in the came block 53 are designed to give the feed dog (not shown) the required moveent to advance the material a step after each stitch and then retract away from the material and to its original position for its next succeed- 30 ing operative stroke.

The rear end of the reciprocating needle holder or rod 23 is arranged in a tubular extension 45 which is suitably secured at one end to the machine frame l2 and projects outwardly therefrom. 35 The front side of this tubular extension 45 is provided with a slot 45 in which the eye 3l on the reciprocating needle holder 23 travels. On this tubular extension 45 is mounted the thread takeup plate forming the subject of this invention, 40 .r

is horizontally disposed. The plate 47 is secured 45 'z to the tubular extension 45 by a screw 5I), this screw passing through a slot 5i in the take-up plate 4l so as to permit of the adjustment of the take-up plate along the tubular extension 45. The cam extension 43 of the thread take-up plate is 50 designed to permit a limited amount of slack in the thread at the start of the forward reciprocation of the needle, this amount of slack being necessary for the formation of .a loop by the needle. It is also so designed that as the needle 55 holder reciprocates it takes up the slack in the needle thread and pays it out as required, thereby avoiding breaking of the thread. It is also so designed that on the retraction of the needle holder, a slight tension is imposed upon the needleGO thread'so as to decrease the size of the loop formed by the needle and insure its being properly caught by the looper. This cam plate also imposes additional tension on the needle thread as the needle holder continues to retract so as to draw the stitch 65 tight. To accomplish these purposes the cam plate 47 can be of various forms, but as shown in the drawings, has a substantially circular salient ing. Y 1

25025;'7541 InlF'ig. 5-therneed1e 24 and needle holder'231are` cam;extension 49.1 The cam 49 does not engage the: needle4 thread until the needle holder has moved forwarda.V short distance and it is therefore apparent that'this distance of movement pro-` videsaV limited slack in the; thread, which slack' isfnecessary-for the; subsequent formation of a loop by the' needle.

Fig; 6 shows the next` successive position of the needleand: needle holder, the needle having entered the .material and havingentered the triangle of threadheld by the looper, the upper legV of'this triangle comprisinga: loop previously formed by the needle and held by the looper and thelower legof this triangle comprising the looper thread 44; During this movement, the length of the needle thread between the eye 3| on the needle holder. 23` and the outlet end of the tubular guide 3.0fis. caught by the-receding end 53 of the cam groovelll and as the needle moves forwardly this length of threadtravels along this receding portion-ofjthe camland is deflected laterally outward onto the salient portion thereof.

Fig. 7 shows a next succeeding position of the needle and needle holder in its forward movement. In this position the length of thread between the eye 3| on the needle holder and the outlet end of the tubular guide 30 is caught by the cam plate in the position shown.

As the needle reaches its fully projected position, shown in Fig. 8, the cam plate 49 is so positioned along the tubular support 45 that the length of thread between the eye 3| on the needle holder and the outlet end of the tubular guide 30 slips around the rounding salient face 52 of the cam and rides down to the base of the cam adjacent the tubular support 45, this portion of the cam being substantially circular for this purpose.

In Fig. 9 is illustrated the start of the returning movement of the needle and needle holder from their fully projected positions. As the needle and needle holder return the needle thread is held at the base of the salient portion 52 of the cam adjacent the tubular support 45 and a tension is thereby imposed upon the needle thread so as to draw upon the loop being formed by the needle in so retracting and limiting its size. This prevents the formation of an excessively large loop by the needle in retracting, which large sized loop, during high speed sewing, is liable to drop down and not be caught by the looper 33, thereby causing the sewing machine to drop a stitch.

As the needle and needle holder move back further the slack in the thread is continued to be taken up by the cam 49 and this cam imposes an increasing tension upon the needle thread so that the stitch just formed is drawn tightly into the material being stitched. When this tension increases to the point Where the thread will no longer be retained on the nose of the cam the length of thread between the outlet end of the tubular guide 39 and the eye 3| on the needle holder slips around the salient face of the cam to the receding part 53 thereof, as best shown in Fig. 10. During the final retracting movement of the needle holder the thread is drawn free from the cam plate 49 to the starting position illustrated in Fig, 5. During this last part of the return movement of the needle holder and needle additional thread is drawn through the tension device 29 for forming the next succeeding stitch.

From the foregoing it is apparent that the takeupplateshown` in Fig. 4v comprises azvery.,y simple,V eflicient and reliable. means for'l taking: up the slack in the needle thread of theqsewingv machine as the needle andy its holder are recipv-4 rocated back and forth during the sewingr opera- A tion. The take-up plate also insures the provi,` sion of the requisite amount ofslack for the formation. of a small sizedloop and positively pre-A vents the formation of an excessively large. loop: during high speed-operation of the machine, such-,10 excessively large loops being in danger of.'A not,v being properly caught by the looper. The take up plate, as shown, alsofinsures that the-stitch. isdrawn tight, thereby. providing firmer and: tighter sewing. It isralso apparent that the takeup plate can be easily applied to standard'ma-f chines now in use without-difculty, theA present take'up plate supplantingan eye mounted on thetubular extension 45 in standard machinesy as. now made.

I claim as my invention:

1. A thread take-up for a heavy dutyy sewing; machine for sewing twine and coarse thread having a reciprocating needle holder arranged parallel with the main shaft and carryinganeedle E- at one .end and having a single thread guide mounted at its other end, a tension adjusting device feeding the thread to said thread guide and means for reciprocating said needle holder, comprising a stationary cam arranged between said thread guide and tension adjusting device and projecting laterally of said needle holder into the path of the length of thread between said tension adjusting device and said needle holder guide, said cam being formed to provide a salient portion, said salient portion moving said length of thread laterally of said needle holder to form and retain a loop in said length of thread each time the needle holder is moved toward and from its extreme retracted position, said salient portion releasing said thread each time the needle holder is fully retracted, the loop formed and held by said cam taking up the slack in said length of thread as said needle holder is reciprocated.

2. A thread take-up for a heavy duty sewing machine for sewing twine and coarse thread having a reciprocating needle holder arranged parallel with the main shaft and carrying a needle at one end and having a single thread guide mounted at its other end, a tension adjusting device feeding the thread to said thread guide and means for reciprocating said needle holder; comprising a stationary cam arranged adjacent to and to one side of said thread guide and projecting laterally of said needle holder into the path of the length of thread between said tension adjusting device and said needle holder guide, said cam being formed to provide a salient portion on that side adjacent said' needle and 60 a receding portion on that side remote from said needle, said cam moving said length of thread laterally of said needle holder to form a loop in said length of thread each time the needle holder is reciprocated from one extreme position to the 65 other and the end portion of said cam adjacent said needle being adapted to hold said loop during a part of the retracting movement of said needle holder and the opposite end of said cam being adapted to release said loop in the fully retracted position of Said needle holder.

3. A thread take-up for a heavy duty sewing machine for sewing twine and coarse thread having a reciprocating needle holder arranged parallel with the main shaft and carrying a needle at one end and having a single thread guide mounted at its other end, a tension adjusting device feeding the thread to said thread guide and means for reciprocating said needle holder; comprising a stationary cam arranged adjacent to and to one side of said thread guide and projecting laterally of `said needle holder into the path of the length of thread between said tension adjusting device and said needle holder guide, said cam being formed to provide a substantially circular salient portion on that side ad- I,

jacent said needle and a receding portion on that side remote from said needle, said cam moving said length of thread laterally of said needle holder to form a loop in said length of thread each time the needle holder is reciprocated from one extreme position to the other and the end portion of said cam adjacent said needle being adapted to hold said loop during a part of the retracting movement of said needle holder and the opposite .end of said cam being adapted to release said loop in the fully retracted position of said needle holder.

4. A thread take-up for a heavy duty sewing machine for sewing twine and coarse thread having a reciprocating needle holder arranged parallel with the main shaft and carrying a needle at one end and carrying a single movable thread guide which is located at its opposite end, a pair of stationary thread guides between said movable thread guide and the needle, a tension adjusting device for feeding the thread to said movable thread guide, stationary thread guides and needle and a third stationary thread guide guiding the stretch of thread between said tension adjusting device and said movable thread guide;

comprising a stationary cam engaging the stretch of thread between said third stationary thread guide and said movable thread guide, said cam being formed to provide a salient portion, said salient portion moving said stretch of thread laterally of said needle holder to form and retain a loop in said stretch each time the needle holder is moved toward and from its extreme retracted position, said salient portion stretch each time the needle holder is fully retracted, the loop formed and held by said cam taking up the slack in said stretch of thread as the needle holder is reciprocated.

PAUL KUHLIG.

releasing said l

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