US2293096A - Thread severing device for sewing machines - Google Patents

Description

` T. A. ANDERSON THREAD ASEVERING DEVICE-FOR SEWINGMACHINES Aug. 1s, 1942.

Fiied May 9, 1939 4tice to pass the oFFlcE-.j

" s Gnmcsroas Them. A. Anderton, mann, c...

assignments, to The Singel-Manufacturing Company, Elixabe mesne of New Jersey N. J.. a corporation Application my s, im, sei-ni No. l212,661

This invention relates to thread severing means and more particularly to thread severing means associated with and forming a part of a sewing machine.

LIn the manufacture of bags, and in many other` instances where articles are stitched one after another it is the pracarticles through a sewing maat a high rate of speed practithey can be fed to the sewing operator.' without stopping or speed of operation of the sewchine operating cally as fast as machine by the slowing down the ling machine during the interval between the final stitching operation on one article and the initial stitching operation on the succeeding article, with the result that the successive articles are connected by a thread chain or a series of thread loops which have of the threads connecting such articles ordinarily is done by the operator with a pairof scissors, even though such a method of severing the threads between the articles-is not satisfactory as it necessitates a separate operation requiring an appreciable amount of the operators time, and, as only one cut between articles is made, it leaves a tail of thread attached to each end of the article.

It has been proposed to equip sewing machines with attachments which would sever the thread after the stitching operation on each article, but such attachments 'have not proven entirely satisfactory due to the fact' that they'have required some operation on the part of the operator, were complicated, required modification of the sewing machine, or left a relatively long tail of threads attached to each end of the article which was stitched. 4

The present invention provides thread severing means for sewing machines which is not open to the above objections to prior thread severing means for sewing' machines in that the thread is severed automatically and immediately after the last stitch upon the article. Furthermore,

of garments, the closing.

to be cut. The cutting succeedingthread loops or the thread chain formed by the continued operation of the sewing machine are destroyed until just prior to the introduction of a succeeding article into va position to be stitched, thereby eliminating not only the thread tail" from both ends of the articles, but also the necessity of the operator to cut the thread between successive articles, and leaving her free to devote her entire time to feeding articles into stitching position.

In accordance with the present invention the sewing machine is provided with cooperating severing elements which are maintained inoperative as lo'ng as the article to be stitched is between them, but which are brought into operation to sever the thread immediately upon the passage of the article from between them,

`to the sharp-edged as the thread will be between the 23 claims. (Cl. i12-asa) making the severing operation entirely independent of the operator, or of the duration of the stitching operation, and insuring the severing of the thread close to the stitched article. The cooperating severing elements continue to operate as long as the machine is operating and there is no stitched article between them so that the thread chain or thread loops which are formed between articles are continuously destroyed until a succeeding article enters between the severing elements, when they again are rendered inoperative. f

Contrary to previously proposed means for severing the `thread after the completion of the stitching operation on any article, the present invention does not depend upon shearing the thread, but severs the thread by crushing it between cooperating ofwhich is mounted to move toward the other with sumcient forceto cause the thread to be given a blow which will sever it. One of the cooperating severing elements is in the form of a pressure or anvil member and the other cooperating severing element is in the form of a hammer member and may have a sharp edge. 'I'he anvil member preferably is carried by the press'er foot ofthe sewing machine and preferably is in the form of a freely rotatable roller so that a diiferent surface will continuously be presented hammer member, thereby to prolong the life of the anvil 'I'he hammer member #preferably is carried by andforms a part of the feed dog of the sewing machine, although it might be formed upon some other part of the sewing machine, such as a pinking roller, if the sewing machine is provided with such a roller. When the anvil lessen wear on and member.

member is carried by the presser foot and is' suilicient force that it will not be raised by an article vto be stitched as it passes beneath the presser foot. Thus, as long as a stitched 'article is passing beneath the pressure or anvil member the latter will be raised to a position where it will not be struck by the hammer member of the feed dog, and the cooperating anvil and hammer members will be maintained'inoperative, but as soon as the stitching operation on the article has been completed neathithe pressure or anvil member, the latter will be forced down into a position where it can be struck 'by the hammer member during the normal cycle of movement of the feed dog, and

anvil and hammer during such movement it will be crushed and severed at the stitch just behind the last stitch on the article due to the fact that the feed thereby dog of a sewing machineV operates in synchronism severing elements, at least onev the feed dog it is resiliently urged downward, but not with and-it has passed from bewith the Ineedle. As the feed dog continues to operate as long as the sewing machine remains in operation, the sharp vedged hammer member carried thereby continues to strike against the anvil as long as there is no stitched article 'between them with the result that the entire length l of thread between stitched articles is literally masticated or chewed away.

The invention will be further described in connection with the accompanying drawing but it is to be understood that such further illustration and description is by way of exemplification and that the invention is not limited thereto except to the extent set forth in the appended claims.

In the drawing:

Fig. 1 is a vertical sectional View through a portion of a sewing machine having the present thread severing means secured thereto.

- fFig. 2 is a horizontalsectional view on line 2-.2 of Fig. 1.

Fig. 3 is a vertical sectional View on line 3 3 of Fig. 1.

Fig. 4 is a more or less diagrammatic view i1- lustrating how the thread between stitched articles-is chewed away, andt l Fig. 5 is a perspective view of the presser foot member of the present device. l

The present invention may be applied to lockstitch sewing machines, chain-stitch sewing ma.- chines, over-edgers, two needle sewing machines, or any other type of sewing machine where the articles to be stitched are passed successively throughthe stitching position.

For purpose of illustration, the invention is shown in the accompanying drawing as applied to a plain lock-stitch sewing machine having the usual head I which carries a presser foot bar 2 and needle 3. The sewing machine also has the usual work-supporting bed-plate 4 provided with a throat plate 5 having an opening 6 .for the needle and parallel slots 1, 3 and 9 for the feeding teeth of a feed dog -Ill. The usual mechanism, a part of which is shown at II, is provided to impart theback and forth and up and down movement to the feed dog to feed the articles to be stitched through the sewing machine in the direction indicated by the arrow. l

In the preferred form of the invention, the usual presser foot of the sewing machine is replaced' by a presser foot assembly which is secured to the lower end of the presser foot bar 2 by the usual thumb screw I2. The presser foot assembly comprises a vertically-extending shank member I3, a sole-plate I4, and a U-shaped yoke member I3 having a base portion I5* and forwardly-extending arms I5. The upper part I6 of the shank member I3 is bent in rectangular or other appropriate shape to conform to the shape i of the lower end of the presser foot bar 2 and is adapted to be slipped-over the lower end of the presser foot bar 2 and securely held thereto by the thumb screw I2 which is received in a slot I1 in one side of the upper portion I6 of the member I3. The lower end of the member I3 is provided at each side with a forwardly-extending ear I3, and the sole-plate I4 is provided interme- 'diate its length with a pair of upwardly-extending ears I9. A pivot pin 20 extends throughlthe ears I3 and I3 and through the forwardly-extending arms I5b of the yoke member I5 so that the yoke member has a swinging movement in a verticle plane about said pin as will hereinafter appear.

The vertically-extending member I3, the soleplate Il, and the yoke member I5 preferably are die-stamped to maintain the cost of manufacture as low as possible, but if desired those parts may be cast, in which case the vertically-extending member I3 and the sole-plate I4 may be made integral. y

A pressure or anvil member in the form of a roller 22 having flanges 23 at each end thereof is mounted for free rotatable movement on an axis pin 24 extending between the arms lh of the yoke member, and rearwardly of the vertically-extending member I3 and in alignment with the needle 2 of the sewing machine.

'I'he rear portion I5 of the yoke member and the roller 22 carried thereby are normally urged downwardly by a spring 25 interposed between the member I3 and the base I5 of the yoke member. The forward end of the spring is received in a recess or socket 26 in the rear face of the member I3, and in order that the force with which the spring will urge the rear of the yoke member and the roller carried thereby downwardly may be adjusted, the rear end of the spring bears against the shoulder on an adjusting screw 21 extending through the base of the yoke member. A lock nut 28 holds the screw in adjusted position.

The presser foot sole-plate I4 is formed with the usual upwardly curved split toe portion 29 under which the articles to be stitched are fed, and through which the needle passes. InY order to provide a more extending gripping surface, the bottom of the sole-plate is made longer than usual, and the rear part thereof is bifurcated to provide an opening 30 through which the pressure or anvil roller extends.

The feed dog is similar to feed dogs now used in sewing machines and includes portions having feeding teeth 3| which extend through the slots 1, 3 and 3 to engage the articles to be stitched to feed them through the sewing machine. However, the feed teeth which pass through the central slot 3 extend rearwardly a sufiicient distance to bring the rear tooth 32 beneath the roller 22 when the feed dog is in its upward and back position. The rear tooth 32 of the feed dog preferably is formed with a knife edge and when the sewing machine is operating and there is no article to be stitched between it and the anvil member, it cooperates with the anvil member, as a hammer, to sever the thread loops formed by the stitching mechanism. The

-anvil roller 22 and the feed dog, including the hammer tooth 32 having th'e knife edge, are made of hard steel to withstand the wear to which they are subjected. In order to better guide the series of chain loops of the chain thread connecting stitched articles beneath the roller 22, the innerl end portion of the part of the feed dog which extends through the slot 3 is provided with a thread guiding groove 33, preferably V-shaped in top plan and having its apex portion disposed upwardly and rearwardly, as illustrated in Figs. 1 and 4.

,As will be seen from Fig. 3, the flanges 23 of the anvil roller overlie the portions of the throat plate between the slot 3 and the slots 1 and 9 at ber I5 and the roller 22 are in their lowermost position, the -anges 23 will rest upon and be supported by those portions of the throat plate. Consequently, in the absence of work, the face portion of the roller 22 between the flanges 23 thereof and with which portion of the roller the Obviously, as the roller 22 passing under the flanges' roller opposed to the hammer tooth 32 is correspondingly elevated, thereby obviating marring of thefs'titchcd work by the sharp edge of the metan.

The spring 25 constantlytends to swing the rear part of the yoke member l and the anvil roller 22 carried thereby downwardly about the pivot pin sothat the portion of the roller between the flanges 23, which is in alignment with the needle 3 and the guiding groove 33 of the feed dog, will be struck by the knife edge of the hammer tooth 32 of the feed dog once during each cycle of the movement of the feed dog.v However, as soon as the article being stitched is fed backwardly` through the sewing machine' far enough to come beneath the roller 22 it raises the roller away from the path of movement ofthe feed dog suiiiciently that the hammer tooth 32 of the feed dog no longer cooperates with the roller to effect a severing action and'that tooth like the other ofthe feed teeth merely functions to feed the articles through the sewing -needle will be threaded when ticle is inserted into stitching position.

The chewed or mastcated portionsof `the thread,

shown at 3l in Fig. 4, will be brushed away by the feeding of the following stitched article through the sewing machine.

During the severing of the thread loops attached to a stitched article and thereafter the extended lower surface'of the presser foot soleplate I4 holds the machine end of the thread between the cooperating severing members and the needle sov that it cannot fly back through the Y eye of the needle on thev next upward movement of the needle bar, and thereby insures that the `As it naturally requires a greater compressive force to crush a coarse thread until -it is severed than it does to crush a fine thread, the tension which the spring exerts to move `the roller 22 downwardly towards the tooth -32` .will be adjusted in accordance with the weight 4o f the thread being used at any particular time.

From the foregoing description it will be seen that the present invention provides a device for machine. As soon as the vstitchedarticle passes beyond the Vvertical center of the roller 22 the spring 25 forces the roller downwardly .to a position where it will be struck by the .hammer tooth 32 in` the next upward rear movement of thel The central part of the roller 22F being in alignment with the needle of the sewing machine and the guiding groove 33 of the feed dog,fthe chain loops formed bythe continued operation of the sewing machine will lie beneath the roller which acts like an anvil to back up the thread when it is being struck by the knife edge of the hammer tooth 32. As the roller 22 is freely rotatable on the axis pin 24, and as the feed dog moves through a counter-clockwise path which is generally elliptical, the edge of the tooth 32 as it strikes the thread lying against the roller; will not onlyl crush the thread until itv breaks, but

also will cause a slight rotative movement of the roller so that a new striking surface of the roller will constantly be presented to the tooth 32, thereby greatly prolonging the life of the anvil roller. 4

As the mechanism for operating the feed dog is synchronized with the mechanism forv operating the needle so that the feed dog moves through its cycle once for each stitch which the needle makes, it will be apparent that the maximum length of the thread left at the end of a ofthe stitch for which'the sewing machine ,is

uen it wm be struck by the teeth 32 'during each "stitched article will b e substantially the lengthi severing the "tail of thread on a stitched article by crushing it between cooperating hammer and anvil members until it breaks, as distinguished from prior devices where the severing of the thread has been by a shearing actio'n, as with shears or other cooperating shearing blades. Also, the present invention provides a device which is wholly automatic in its operation and which'not only severs the tail of thread on a stitched article at the stitch following the last stitch madeon the article but also masticates or chews away the entire chain of thread loops between successive articles up to'v an initial stitch on a following article, so that the tail of thread is eliminated from both ends of the article.

While the invention is particularly adapted for sewing machines in which successive articles to be stitched are fed through the sewing machine v or anvil member carried bythe presser foot for coaction with said severing member to sever a thread passing between said severing member and the pressure or anvil member, said pressure oranvil member being. mounted Vfor movement toward or from the severing member and being moved from the severing member to an inoperative position'by a stitched article tween it and said severing member.

2 .f1n a sewing machine having a feed dog and passing bea presser foot, athread severing member carried cycle of movement of lthe feed dog. 'Ihus the chain of thread loops formed between the final stitch upon one article and thevinitial stitch on the succeeding article, by the continued operation of the sewing machine, will -repeatedly be subjected to the cooperating severing action of the roller 22 and the hammer tooth 32, with the result that the entire chain of thread loops will be masticated-or chewed away until the very instant the succeeding article isfed rearwardly far enough to pass beneath the roller 22 and thereby raise the roller again to its inoperative position.

by the feed dog, a pressure' or anvil member carried bythe presser foot for movement toward and from the 4severing member` carried by the feed Vdog, and a `spring member for resiliently urging 4thebpressure or anvil member toward the severing member carried bythe' feed dog.

3. In a sewing machine having a feed dog and a coacting presserfoot, a severingmember carriedby the f eed dog, a member pivotally connected to the presser foot for movement toward orvfrom the feed dog, a rotating pressure or anvil member carried by said movable member for a succeeding ari coaction with the severing member of the feed dog, and means engaging said movable member for constantly urging the pressure or anvil member toward the severing member carried by the' feed dog.

`fl. A sewing machine having a feed dog and a coacting presser foot, a severing member carried bythe feed dog, a member pivotally connected to the presser foot for movement toward and from the feed dog,l arotating pressure or anvil member carried by said movable member for coaction with the severing member of the feed' dog, and means engaging the movable member for constantly and resiliently urging said pressure or anvi1 member toward said severing member, said pressure or anvil member being moved away from the feed dog to a position inoperative to cooperate with said severing member by the interposition of a stitched article between it and said severing member.

5. In a sewing machine having a presser foot and a feed dog, arotarypressure oranvil mem- `ber carried by the presser foot, and a severing hammer tooth carried by the rear portion of the feed dog and adapted to cooperate with said rotary` pressure or anvil member to sever thread ati tached to a stitched article.

6. In a sewing machine'having a presser foot and a feed dog, a rotary pressure or anvil member carried by the Vpresser foot and mounted to move toward and frornthe feed dog, spring means normally urging said rotary pressure or anvil member toward said feed dog, and a severing tooth carried by the rear `portion of said feedY dog for cooperating with said pressure or anvil member when it is in its position nearest said feed dog, to sever thread attached to a stitchedarticl.

'7. Ina sewing machine, a presser foot assembly including a presser foot portion and a yoke having forwardly-extending arms, a rotary pressure or hammer member mounted between said arms, spring means normally urging said yoke and pressure or hammer member towards the path of stitched articles through the machine, a feed dog, and a sharp-edged hammer tooth carried by the rear portion of said feed dog for cooperating with said rotary pressure or anvil member to sever thread attached to a stitched article, said yoke member and the pressure or the threads connecting such articles comprising a pressure or anvil member carried by the lpresser foot, a hammer member having a sharp edge carried by the feed dog of the sewing machine adapted to cooperate with said pressure or anvil member, means normally urging said pressure or anvil member to a position operative to cooperatewith said hammer member, said pressure or anvil beingraised to an inoperative position by the interposition of a stitched article between said pressure or anvil member and said hammer member but again being returned to a position operative to cooperate with said hammer member'immediately upon the passage of an article from between them whereby upon continued operation of the sewing machine said pressure or anvil member and said hammer member continue to.

cooperate to chew or masticate the threads connecting successive articles from immediately after the passage of one article from between said members until immediately prior to the entry of a succeeding article between them.

9. In a sewing -machine a presser foot assembly adapted to be detachably connected to a presser foot bar of a sewing machine and comprising a presser foot member, a generally U- shaped Ayoke member having the arms thereof extending forwardly, a rotary pressure or anvil member mounted between said forwardly-extending arms of the yoke member and means for normally and resiliently urging said yoke member and the pressure or anvil member carried thereby texan operative severing position, and a severing member'carried by the rear portion of the feed dog of the sewing machine and adapted, when said pressure or anvil member is in its operative severing position, to cooperate therewithto sever threads interposed between them.

10. In al sewing machine, a rotary pressure or anvil member carriedby the presser foot of the sewing machine, means for normally and resiliently urging said pressure or anvil member to an operative severing position, said pressure or anvil member having a radially-extending flange at the ends thereof adapted to bear upon a portion of the throat 4plate of the sewing machine to support the pressure or anvil member when the pressure or anvil member is in its operative severing position, and a severing member carried by the feed dog Vof the sewing machine and adapted to cooperate with the portion of the pressure or anvil member` between the end flanges thereof rto sever thread interposed between said severingv member and the pressure or anvil member-when the latter is in its operative severing position, said pressure or anvil member being moved to a position inoperative to cooperate with said severing member by the interposition of a stitched article between them but being returned to operative severing position immediately upon the passage of said ,article from between them4 11'. In a sewingmachine having apresser foot and a feed dog, a workfresponsive severing member located behind said presser foot, a severing member carried by the feed dog and adapted dury ing the movement of the feed dog to cooperate behind said presser-foot iwith said rst-mentionedservering member to sever thread attached to a stitched article, said presser lfoot holding the machine endof the thread after a severing operation to prevent unthreading of the sewing machine needle.

12. In a sewirg machine, a feed dog, a severing member carried by the feed dog, a second severing member for cooperating with the severing member carried by the feed dog located at the side of the path of stitched articles passing through the sewing machine opposite the feed dog, said second severing member being mount- A ed for movement toward and from the' severing member carried by the feed dog, and being moved away from saidl severing member to an inoperative position by the interposition of a stitched article between it and the severing member carried by -thefeed dog. r

13. In a sewing machine, a feed dog, av severing member carried by the feed dog, a pressure or anvil member for cooperating with said severing member 'located at thel side of they path of stitched articles passingv through the sewing machine opposite thefeed dog, said pressure or anvil member being mounted for movement toward and from the severing member and being movedgaway from said severing member to an inoperative position by the interposition of a stitched article between it 'and the severing member carried by the feed dog.

' 14. In a sewing machine, a feed' dog, a severing member carried by the feed dog, ya second severing memberfor cooperating with the severing member carried'by the feed dog located at the. side of the path of stitched articles passing through the sewing machine opposite the feed dog, spring means for normally urging said second severing member toward the severing member carried by the feed dog, said second severing member being moved away from the severing member carried by .the feed dog to an inoperative position by the interposition of a stitched article between it and the severing member carried by the feed dog.

15. In a sewing machine, a feed dog. a severing member carried by the feed dog, a pressure or anvil member for cooperating with said severing member located at the side-of the path of stitched articles passing through the sewing machine opposite the feed dog, spring means for normally urging said pressure or anvil member toward said severing member, the pressurewith which vsaid spring urges said pressure or anvil member to- 39 ward said severing member being such that the pressure or anvil member will be moved away from said severing member to an inoperative position by the interposition of a stitched article between the pressure or anvil member and the being disposed in spaced relation to 'said wrko support in the absence of work, and means effective upon operation of the machine for imparting uniform operative movements to said complemental thread-severing member in successive stitch-forming cycles.

17. In a sewing machine having stitch-forming mechanism including a reciprocatory needle, two cooperating thread-severing members clisnosedrearwardly of the path of needle reciprocation and maintained separated by work passing through the machine, one of said members beine,` movable in the direction of travel of the work and the other being movable in a direction substantially normal tothe plane ofthe work into` thread-severing engagement with Veach other. 55

18. In a sewing machine having stitch-forming mechanism including a reciprocatory needle. a

presser-foot. two lcooperatingthread-severing l members maintained separated by work passing through the machine, one of said members being movable inthe direction of travel of the work and the other being movable relative to the presser-foot in a direction substantiallynormal to the plane of the work into' thread-severing y engagement with each other.

19. A sewing machine having a needle, a feeddog, a throat-plate having needle and feed-dog clearance apertures, means for imparting workv advancing movements to said feed-dog, said feed-dog having a thread-severing edge disposed in rear of said needle-aperture, a spring-pressed presser-foot having `a planar work-engaging surface opposed to said feed-dog, and complementary thread-severing means disposed in rear of the planar work-engaging face of said presserfoot and in rear of the thread-severing edge of the feed-dog as the latter begins its feed-stroke, said complementary thread-severing means be- 'ing yieldingly urged towards said throat-plate for 4 engagement by said thread-severing edge in the absence of work, whereby the thread trailing rearwardly from the stitching point of the machine will be severed when said thread-severing edge of the feed-dog, in the feed-stroke of the latter, engages said complementary thread-severing means.

20.l In a thread-chain severing device for sewing machines, a presser-foot having a supporting shank, a work-.engaging sole-plate carried by said presser-foot shank and provided with a needle-aperture, a work-responsive member pivotally mounted upon and extending rearwardly from said shank for movement about an axis transverse to the length of said sole-plate, and a thread-chain severing element carried by said member for movement into and out of the plane of the work-engaging face of said sole-plate.

21. In a thread-chain severing device for sewing machines, a presser-foot having a supporting shank, a work-engaging sole-plate carried by said presser-foot shank and provided with. a needle-aperture, a work-responsive member pivotally mounted upon and extending rearwardly from said shank for movement about an axis transverse to the length of said sole-plate, a peripherally flanged roller journaled upon said member for turning movements about an axis substantially parallel to the pivotal axis of said member, said roller providing a peripheral anvilface movable into and'out of the plane of the work-engaging face of said sole-plate.

22. In a thread-chain severing device for sewing'machines, a presser-foot having a supporting shank, a wor -engaging sole-plate carried by said presser-foot shankv and provided with a, needle-aperture, a work-responsive member pivotally mounted upon'and extending rearwardly from said shank for movement about an a'xis transverse to the length of said sole-plate, a thread-chain severingelement carried by said member, a, spring bearing uponv said member in a direction to depress saidsevering element to- -wards the plane of the work-engaging face oi' said sole-plate, and means providing for adjustment of the pressure of said spring upon said member. f

23. In a sewing machine, including a presserfoot and a. feeder movable relative to the foot.

' means carried by the presser-foot and feeder for cooperativeh action to sever a thread drawn therebetween by a piece of material as the latter thread remaining attached to the machine needle after the thread has been severed.'

'THOMAS A. ANDERSON.

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