US1549248A - Chain-stitch sewing machine - Google Patents

Description

Aug. 11, 1925. 1,549,248

A F FIFIELD CHAIN STITCH SEWING MACHINE Filed Jan. 7, 1921 2 Sheets-Sheet 1 INVENToR 46M KFM" BY 2 Sheets-Sheet 2 Aug. l1, 1925.

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Maf/QM ATTORNEY Patented Aug. 1,1, 1925..

UNITED STATES.

PATENT OFFICE'.

ALBERT F. FIFI'ELD, 0F NEWARK, NEW JERSEY, ASSIGNOR TO THE 'SINGER MANU- FACTURING COMPANY, 0F ELIZABETH, NEW JERSEY, A GORPORATIO'N 0F NEW JERSEY.

CHAIN-STITCH SEWING MACHINE.

Application led January 7, 1921. Serial No. 435,599.

To all whom it may concern.'

. Be it known that I, ALBERT F. FIFIELD, a citizen of the United States, residing at' Newark, in the county of Essex and State lof New Jersey, have invented certain new and 'usefullmprovements in Chain-Stitch Sewing Machines, of which the following isa specification, reference being had therein to the accompanying drawings.

This invention relates to improvements in sewing machines and especially to that class of sewing machines in which the mechanism is automatically stopped after making a desired predetermined number of stitches, as for example, in button sewing, tacking and the like. It relates particularly to a single chain-stitch sewing machine employing a rotary looper and to means whereby the free end of thread may be held for a given time at the beginning of each of a series of stitch- .ing operations, such for instance, as are employed in attaching a button to a fabric article.

This machine is distinct from those in -which separate means is provided to pull voff suiicient thread from the supply to form the first loop. In work performed by suc'h machines the first two or three stitches are not set properly and they are therefore loose and unsightly, and tend to become further loosened and unravel.

It has been found that if, in attaching articles to fabric with a' single chain-stitch lnachlne' employing a rotary -looper as 1n the present instance, the vfree end of thread after it has been drawn beneath the work is held during the formation of the 'iirst loop, there will be no loose stitches at'the beginning of the sewing operation and the article will betightly and securely fastened to the fabric regardless of the thickness of this fabric. p

A single chain-stitch is .preferable in many instances .to a lock-stitch in attaching articles such as buttons as a single length of thread is employed and buttons may' be sewed to different thicknesses of fabric equally well without any,adjustment of the stitching mechanism.` When a lock-stitch is used there are two short lengths of thread and four free ends for each button and unless the tensions are properly land carefully adjusted one of thesethreads is shorter than the other with a consequent tendency of the loops of the longer thread to slip off the ends of the shorter thus causing the button to loosen and come olf. Furthermore to properly attach the buttons with a lock-stitch the tensions should be adjusted for' different thicknesses of fabric..

It is therefore an object of this invention to provide thread-controlling mechanism so that a single chain-stitch sewing machine employing a rotary looper may be used to tightly and securely attach buttons to fabrics of various thicknesses in an expeditious and reliable manner. It is also an object of this invention to provide means whereby the operation may be performed without the formation of loose stitches -at the beginning of the operation. It is a further object of the invention to prevent a long free end of thread being left at the end of the sewing operation, thus producing neater work and obviating wastage of thread, and it is a still further object of this invention to provide means which will automatically grip the free end of the thread beneath the work at the proper 'time at the beginning of each of a series of stitching operations until the first loop is formed and then release the same.

Other objects and advantages of the invention will appear as the description thereof proceeds.

In its referred form the invention comprises a at resilient nger or nipper pivoted -in a recess in the under side of the throatplate with a link connecting the same and a lever pivoted on the overhanging arm of the machine, and cam means mounted on the cam-wheel which operates the Work-jogging mechanism for swinging said lever and through it the nipper to nip and release the free end of thread in certain timing relation with the needle actuation.

For a detailed description of the invention reference is made to the accompanying drawings in which Fig. l is a rear' side. elevation of the machine. Fig. 2 is a sectional e-levation taken just outside the looper mechanism looking in the direction of the standard. Fig. 3 is a bottom plan view of the throat-plate detached. Fig. 4 is a section of a part of the machine bed adjacent the stitchingpoint on a somewhat enlarged scale showing the positions' of the elements just after the free end of thread has beennipped bythe nipper. Fig. 5 is a section similar to Fig. 4 showing the needle and cupy when the nipper starts to release the rotary looper 9 adapted to cooperate with the needle 7 to form a single thread chainstitcli. The specific embodiment 'shown' is assembled asa flat button sewer by which a series of separate and distinct sewing op-v erations are performed such as sewing on a button but although the invention is particularly adapted for use in such a machine it is not limited thereto as it may obviously be-used in other machines adapted to perform a series of separate sewing operations in which a needle and rotating looper are employed to'forin a single thread chainstitch.

As is usual in such machines, mechanism is provided for producing relative jogging movements between the work and the needle and although either the needle or thejvork may be given the jogging movements, in the machine shown the work is given these movements. This mechanism, which is substantially that disclosed in the patent to A. F. Fifield No. 1,316,022, dated September 16, 1919, comprises a work-clamp and button-holder 10 comprising the jogging bar 11 which extends longitudinally -of and rests upon the work-arm 2. To the forward end of the bar 11 is secured the fabric-supporting plate 12Yupon which rests the buttonclamp comprising the opposed button-gripping jaws 13 for holding the button B against the fabric F. The jaws 13 are carried by the spring-pressed arm 14 secured upon the block 15 mounted upon the rear# ward end of the bar 11. Jogging movements are imparted to the work-holder from cani-grooves in the cam-wheel 16 by mechanism fully disclosed in said patent above mentioned, said cam-wheel being rotated at a proper relative speed to the stitching mechanism by suitable connections within the frame of the machine to the means for driving the stitching mechanism as is well known.

Stop mechanism to automatically stop the machine at the end of a stitching operation is designated as a whole by the reference character 17 and is substantially that disclosed in the patent to J. J. Sullivan, No.

777,564, dated December 13, 1904. Mounted upon the arm 4 'between the thread supply and the take-up 8` is a thread-nipper or tenris/rasee `sion device 18 opeiated intermittently by suitable mechanism as a cam 18 on the shaft S within the arm or standard so as to nip the thread to prevent its being drawn off from the supply during a certain portion of each reciprocation of the needle. The tiniing is such that the nipper acts to nip the thread just before the needle enters the work on its down stroke and holds the same nipped until the needle has moved about three quarters of its distance above the 'work on its up stroke or when the looper has partly pulled the needle-loop from the needle to spread the same when the grip of the nipper on the thread is released. The thread is released when the wheel 18 is on the raised portion of the cam 18 as shown in Fig. 2.

The mechanism so far described isV old in the prior art.

In carrying out my present invention use is made of a second tension-device or threadnipper the structure of which is preferably as follows. The throat-plate 19 is formed on its under side with a recess 20 communicating with the needle opening 21 in said plate. Fulcrumed at 22 in said recess is a tlireadnipping member 23 provided with a preferably resilient flat thread-nipping poi tion or arm 24 which is'so positioned as to swing across the needle opening and nip or detain the thread against the under surface of the 4tliroat-platewhen the member 23 is swung on its pivot 22 as presently to be described. Retained on the under side-'of the throat-plate in any suitable manner as by -a pin 25 is a spring plate 26 which extends across the nipping portion 24. EX- tending through the body of the work-arm 2 is an adjusting screw 27 which bears at its end against the spring 26 and therefore by adjusting this screw toward or from the springv the pressure of the spring on the arm 24 and therefore the pressure which thisv arm exerts on the thread when the same is nipped thereby, may be varied as desired. The screw 27 may be held in adjusted position bythe lock-nut 2S.

The arm 24 of the nipper member 23 is wiped across the needle opening 21 in certain timing relation with the movements of the needle and looper at the beginning of a stitching operation byltlie action of a cam member 29'secured on the periphery of the cam-wheel 16 by means of screws 30. These screws are screwed into the cam-wheel and lpass through elongated slots 31 in the cam ably a metal plate curved as shown to fit the curvature Aof the periphery of the camwheel 16 and is rovided with inclined cam surfaces a, b, o, dP and e.

Suspended from the arm 4 is a hanger or bracket 32 journaled in the lower end of which is a pin 33 on one end of which is rigidly secured intermediate its ends a lever 34 provided adjacent its opposite ends with cam-follower portions 35 and 36 which are in alignment with the cam surfaces a, b, c, d and e as shown in Fig. 2, so that the lever 34 is rocked inopposite directions as these surfaces contact with and pass by the cam followers 35 and 36. Also rigidly secured to the pin 33 is a depending lever 37 connecte-d by an adjustable link 38 pivoted to its lower end with an arm of the nipper member 23 by means of a screw 39 extendingthrough a slot in the throat-plate. The link 38 is made in two sections 41 and 42 adjustably connected together by a screw and slot connection 43 so that its length may be changed if desired. It will therefore be seen that rocking of the lever 34 by the cam member 29, will through the pin 33, lever 37 and link 38 swing the nipper member 23 about its pivot 22.

The cam member 29 is so placed on the cam-wheel 16 and the. inclined surfaces a, b, c, d and e are so spaced on 'said member that at the beginning of a stitching operat1on the parts are in the relative positions shown in Fig. 1, the cam-follower 36 being forced outwardly by the cam member 29 to hold the nipper-arm 24 retracted in .ineffective thread-nipping position as shown in Fig. 3, the needle being in its raised position as indicated. As the machine is started the distance between surfaces e and d is sufiicient to retain the arm 24 in its retracted orno-n-thread-nipping position u ntil the needle has made one complete reciprocation and the looseI end T of thread T has been drawn below the work by the looper 9. As the needle starts'on its second down stroke cam-follower 36 rides down inclined surface d while surface b forces 'folllower 35 outwardly rocking the levers 34 and 3 7 and swinging member 23 on its pivot towlpe arm 24 across the needle .opening and nip the free end of thread against the under surface of theu throat-plate, this free end, as mentioned above, depending below the work. The arm has passed 'across the needle opening into the dotted positionv 24 in Fig. 3 and full line in Fig. 4, and yieldingly nipped the thread end at about the time the needle has passed half way to the work as shown in Fig. 4. It is retained in this position by the dwell on cam member 29 between the surfaces a and b until the needle has completed its second reciprocation and has reached the limit of its second up stroke as shown in full lines in Fig. 5.

. dicated in Fig. 5.

At this time, as the needle starts on its third down stroke cam surface c begins to force cam follower-36 outwardly and through the connections with member 23, arm 24 is moved back again into its ineffective position the free endT of thread being released thereby about the time the needle is one quarter the way to the work on its third down stroke. The approximate positions of the needle and looper at the time the-thread is released are. indicated by dotted lines in Fig. 5. The thread is nipped on the supply side of the needle by the nipper 18 on each down stroke of the needle at about the time the point of the needle enters the work and is not released by such nipper until the needle is nearly to the limit of its next up stroke.

Since the beginning end of the thread is yieldingly held by the arm 24 during the second reciprocation of the needle, it follows thatpart of the thread demanded by the looper-beak 9 during this time in seizing and spreading the. loop is supplied by the free end of thread which is drawn back past the nipperl 24; the latter being ad]usted weaker than the nipper 18. The thread end then occupies substantially the position in- That is as the thread is nipped by both nippers 18 and 24 and they nip lthe thread unequally, 18 gripplng it more tightly than nipper 24, during the first part of the formation of the loop the free end of thread T is drawn back through nipper 24 from the position shown in Flg. 4 tosubstantially that shown in Fig. 5. However as there is not enough thread in this free end to form the entire loop as spread around the looper, ifnipper 24 continued to suppl)7 thread the free end T would be drawn away from this nipper and no loop would be formed and consequently no stitches. Therefore just before the looper has moved to the position shown in Fig. 5 and drawn the free end T of thread back to substantially the position shown in this figure the nipper 18 releases the thread and the remainderrequired for the forma.- tion of the loop is drawn ofi' from the supply. It will be clear from this that the amount of free end of thread left hanging from the work at the completion of a stitching operation is greatly reduced thus preventing thread wastage. In fact the short free end left is sewed in with the remaining stitches of the sewing operation.

As the free end T of thread is detained by the arm 24 until the loop is spread, the next loop thrown out by the needle on its third down stroke is seized by the looperbeak 9" and drawn through the first loop thus properly concatenating the thread-loops and the first stitch is drawn tightly as it The thread is led Jfrom a supply (not shown) through nipper 18, thence to a guide 44' and tension member 44 on bracket 44, then through a`yieldable thread-guide 45 to take-up 8, through guides 47 and 48 to a thread-check 49 and then to the needle-eye as shown. The guide 45 is adapted to yield f'upwardlly against spring 45 if tension on thread exceeds a certain amount.`

Also pivoted tothe under side of the throat-plate 19 at 50 is 'a thread-cutter 51. This cutter is connected so as to be operated by the overthrow action of the stop mechanism 17, to cut the work limb of the loop spread around the looper at the end of the stitching operation and to cut this limb close to the lower surface of the work. This thread-cutter is substantially that disclosed in my prior Patent No. 1,251,451, dated December 25, 1917.

It will be clear from the foregoing disclosure that I have provided a simple and reliable mechanism adapted to be employed with asingle chain-stitch sewing machine so that buttons and other articles may be tightly and securely fastened to fabric withY this typet of machine without the formation l of loose' stitches at the beginning vof the sewing operation and without leaving a long 4free end of thread with its consequent unsightliness and thread wastage.

Having thus set forth the nature of the invention, what I claim herein is- 1. In a sewing machine, the combination witha work-rest and stitch-forming mechanism including a needle, a rotary chamstitch looper and an intermittently operated thread-nipper, of a second thread-nipping device weaker than the first mentioned thread-nipper and adapted to be moved to grip a free end of thread beneath the workrest, and automatic means for operatingr said nipper so constructed and arranged as te hold the second nipper inactive during the first reciprocation ofthe needle while the free end of the thread is beingdrawn beneath the work by the looper and to operate the second nipper during the` second reciprocation ot the needle to retain the thread.

2. In a sewing machine, the combination with a work-rest and stitch-forming mechanism including a needle, a rotary chainstitch looper and an intermittently operated thread-nipper, of a second thread-nipper weaker than the first-mentioned thread-nipper and disposed beneath the work-rest, means for holding the second nipper retracted during the first reciprocation of the needle and while the free end of thread is being drawn beneath the work by the looper, and means for then advancing the nipper to detain and tension the thread until the needle has completed its second up stroke and the loop is spread by the looper.

v3. In a chain-stitch button sewing maamazes chine, the combination of stitch-forming mechanism including a needle, a rotary looper and an intermittently operated thread-nipper, a work-holder and means for producing relative jogging movements between the work-holder and needle, a second thread-nipper weaker than the rst-mentioned thread-nipper and mounted benezth the work-holder, and ineffective during he first reciprocation of the needle and w1 `tile the free end of thread is being drawn beneath the work by the looper, and mean.c for causing the thread end to be yieldingly detained by the second nipper substantially throughout the second reciprocation of the needle and until the loop has been spread by the looper.

4. In a sewing machine, the combination with a work-support and stitch-forming mechanism including a reciprocating needle, a rotary chain-stitch looper and an intermittently operated thread-nipper, of a second thread-nipper weaker than the first-mentioned thread-nipper and disposed below the work-support, means for moving the second thread-nipper to catch the thread end drawn through the work by the looper and hold such thread end yieldingly during-.the next stitch-forming cycle, whereby thread demanded by the action of the stitch-forming mechanism is supplied by a portion of the free end of thread being drawn back throu h the second nipper, thereby shortening t e beginning thread end.

5. In a sewing machine having a stitchforming mechanism including a needle, a r0- V tary looper and a work-support, in combination, a thread-nipper, a thread take-up located between the nipper and the needle, a second thread-nipper weaker than the firstmentioned nipper and mounted beneath the work-support, means for operating the first nipper to nip the thread'from substantially the time the needle enters the work on its down stroke until the looper has seized and partly drawn oft the loop and then release the thread, and means for operating the second nipper at the beginning cfa stitching operation to nip the free end of thread during the first part of the second down stroke of the needle and retain the same until the loop has been spread by the looper.

6. In a single thread chain-stitch sewing machine having stitch-forming mechanism includmg a needle, a rotary looper and a .work-support, in combination, a thread-nipper, a thread take-up located between the nipper and the needle, a second thread-nip means for rendering the second nipper inei`- feetive during the rst reeiprocation of the needle at the beginning of a stitching operation and While the free end of thread is being drawn beneath the Work by the looper, and then causing the thread end to be detained by the nipper during the second reciproeation of the needle until the loop has been spread by the looper.

7. ln a sewing machine, the combination with a Work-support and stitch-forming instrumentalities including a reciprocating needle, of means below the work-support for nipping the free end of needle-thread, and stronger means above the work-support for holding the thread While the stitch-*forming instrumentalities operate to pull thread back through the lower nipping means, thus sh0rtening the beginning thread end.

ln testimony whereof, l have signed my 20 name to this specification.

ALBERT F. FIFlELD.

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