US1251451A - Thread-cutting mechanism. - Google Patents

Description

A. F. FIFIELD.

THREAD CUTTING MECHANISM.

APPLICATION FILED APR. 1. 1914.

1,251,451. Patented Dec. 25,1911.

2 SHEETS-SHEET 1.

WITNESSES: INI/EN TOR A. F. FIFIELD.

THREAD CUTTING MECHANISM. APPLICATION FILED APR. I, I914.

1,251,451. Patented B01125, 1917.

2 SHEETS-SHEET 2.

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IN I/E N TOR UNITED STATES PATENT OFFICE.

ALBERT F. FIFIELD, OF ELIZABETH, NEW JERSEY, ASSIGNOR TO THE SINGER MANU- FACTURING COMPANY, A CORPORATION OF NEW JERSEY.

THREAD-CUTTING MECHANISM.

Specification of Letters Patent. Patented Dec. 25, 1917.

Application filed April 1, 1914. Serial No. 828,662.

To all whom it may concern:

Be it known that I, ALBERT F. FIFIELD, citizen of the United. States, residin at Elizabeth, in the county of Union and tate of New Jersey, have invented certain new and useful Improvements in Thread-Cutting Mechanisms, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention has for-its object to provide simple and effective means for severing the needle-thread at the completion of a succession of stitches, and insuring the effective cooperation of the stitch-forming elements in the production of the initial stitches succeeding said severing action. The improvement, although not limited to employment with any particular type of stitchforming mechanism, is specially adapted to that class of sewing machines employing a reciprocating needle and a loop-taker adapted to detain thread-loops seized in one needlethrust until the succeeding needle-thrust.

According to the present invention, in its preferred form, a single chain-stitch rotary looper cooperates with the needle in the production of stitches, and needle-thread nipping means are provided between the needle and thread supply, and a thread-severing implement is mounted beneath the workplate and intermediate the needle and looper,

means being provided for effecting the simultaneous action of the thread-nipping and severing means upon the needle-thread at the completion of the final stitch-forming cycle of a group or succession. The needle-bar is preferably provided with a laterally offset thread-eye acting in conjunction with fixed thread-guides as a take-up or stitch-setting element, and intermediate the same and the tension device is disposed an eyed slack-producing thread-arm having an operative connection with a controlling cam whereby a reserve length of thread is drawn from the thread-supply through the tension preparatory to a thread-severing action and is given up in the initial stitch-forming cycle of a' succeeding group or succession to provide slack needle-thread for beginning the series or succession of stitches following such thread-severing action.

The invention will be understood by ref erence to the accompanying drawings, in which Figure 1 is a rear side elevationio'f a fiat-button sewing machine of the "well tion of its actuating means. Fig. 6 is a sec--.

tional plan view ofthe face-plate of the bracket-arm with the needle-thread nipping device, and Fig. 7 is an enlarged detail view showing a portion of the nipper-actuating means.

The machine shown in the drawings is of that class represented in the United States Patent to J. J. Sullivan N 0. 777,561, of December 13, 1904, and contains the stitchforming mechanism of my application filed April 1, 1914, Serial No. 828,663. The frame is constructed with the usual bed-plate 1 and bracket-arm composed of the hollow standard 2 and tubular overhanging arm 3 terminating in the head 4: in which is journaled the needle-bar 5 carrying the eye-pointed needle 6 which cooperates with the rotary single-chain-stitch looper 7 secured upon the rotary shaft 8 journaled beneath the bedplate.

The looper-shaft 8 carries upon its rearward end the transversely grooved pulley 9 connected by means of the belt 10 with a similar pulley upon the main-shaft mounted in the bracket-arm and provided upon its rearward end with the loose grooved pulley 11 and the fixed grooved pulley 12 having connected therewith the stopping cam 13 formed with the shoulder 14 and adjacent peripheral recess 15. Cooperating with the cam 13 is the tapered upper extremity 16 of a spring-pressed plunger-bar carried by the vibratory lever 17 which is pivotally mounted by means of the cross-pin 18 within a transverse slot of the rocking plug 19 journaled in a fixed socket 20.

The lever 17 is yieldingly maintained in contact with a suitable seat of'the'bracket member 21 by means of the pin 22 pressed against the opposite face thereof by means of the surrounding spring 23 within the transverse socket 24 of the bracket member 25 The lever 17 is normally pressed into" i the range of a'ctionof the'cam 13 by a spring in Fig. 1, by a spring-pressed catch lever 26. The stop-lever 17 is adapted to be thrown into retracted position by an angle-lever fulcrumed at 27 upon the bracket members 21 and 25 and comprising the lateral arm 28 apertured to receive the usual treadle-rod and the depending arm 29 whose extremity rests upon the rear side of the lever 17.

The machine is provided with the usual controlling cam 30 fulcrumed at 31 upon the standard 2 and driven by a suitable connection with the main-shaft, this cam having upon its inner face one or more tripping lugs 32 adapted for engagement with the tail of the catch-lever 26 to release the stopping lever 17 in stopping the machine. Suitable connections are shown between the cam 30 and the work-holder for imparting to the latter the requisite work-shifting movements relative to the stitch-forming mechanism.

Secured upon the under face of the throatplate 33 is the bracket-piece 34 having an offset portion carrying a fulcrum-stud 35 entering an aperture in the throat-plate and having journaled thereon an angle-lever formed with the lateral arm 36 and the longer longitudinally extending arm 37 affording the shank of the transversely extending hooked thread-engaging implement 38 of which the throat 38' may be sharpened to form a knife-edge for engaging and severing one limb of a needle-thread loop detained around the body of the looper 7 as represented in Fig. 5. The thread-engaging implement 38 has'a path of movement upon the fulcrum-stud 35 across the elongated needle-aperture 33 of the throatplate.

The arm 36 of the angle-lever has a depending pin 39 embraced by the forked extremity 40 of a transverse arm 41 of the cutter-actuating bar 42 mounted in suitable bearings 43 beneath and longitudinally of the bed-plate and provided at its rearward end with the depending stud 44. The stud 44 is embraced by the forked extremity 45 of the lateral arm 46 of a bellcrank-lever mounted upon the fixed fulcrum-stud 47 del per 51 to throw the driving belt from the loose pulley 11 to the fast pulley 12, the arm 17 of the stop-lever is temporarily retracted from the pin 49 until the catch-lever 26 is tripped to restore the stop-motion device to stopping position when the aperture 50 of the arm 17' again embraces the pin 49 and in the side-throw of the stop-lever in 0pp0sition to the buffer-spring 23 under the momentum of the moving parts, the bellcrank 46 48 is rocked, and through the bar 42 the thread-severing implement 38 is shifted from the full line position represented in Fig. 5 temporarily to dotted line position, so as to cause the operative portion 38 to seize and sever one limb of the needle-thread loop a, after which the recoil of the lever 17 under the action of the spring 23 restores the parts to their full-line position.

To insure the severing of the thread under such action of the implement 38, the face-plate 52 of the bracket-arm head has secured thereon by screws 53 the superposed nipper-plates 54 and 55, the inner one having the upturned lips 56 embracing the edges of the superposed plate and provided with thread-guiding notches 57, the free end portion of the outer plate being spaced slightly from the inner plate to normally permit the free passage of the thread through the guide-notches 57.

Secured to the inner face of the faceplate 52 also by means of the screws 53 is a block 58 forked to receive an inwardly pro ecting portion 59 of the curved nipperlever 60 fulcrumed therein by means of the cross-pin 61. Suitably mounted upon the rearward side of the bracket-arm is the twopart push-rod 62 of which the forward end is adapted to enter an aperture in the faceplate and to engage the extremity of the rearward arm of the nipper-lever 60 whose forward arm is adapted to press upon the outer member 55 of the thread-nipper to nip the thread passing beneath the same. The rearward extremity of said push-rod 1s shown (Fig. 7) slightly rounded at one s1de for engagement with the beveled extremity 63 of an arm 64 secured upon and moving with the stop-lever 17.

The two parts of the rod 62 are normally pressed apart by the spring 65surrounding the forward section and interposed between the collar 66 thereon and the socketed end 67 of the-other section in a manner well known, to afford a-yielding connection between the parts. The thread-nipper is normally open,'and therefore inactive upon the thread, in which condition it remains throughout each stitching operation, but Just as the stop-lever 17 is tilted sidewise 1n finally arresting the operation of the machine, it acts through its described independent connections to simultaneously effeet the nipping of the thread and the operative movement of the severing implement 38, WhlCh latter acts upon a section of thread secured to the material at one end from wh1ch it passes around the looper and extends upwardly through the now closed nipper, thereby preventing a possible failure of the severing action.

As the last thread-loop of the series or succession has the one of its limbs attached to the work severed by the implement 38, a suflicient end of thread would not be normally left to provide for the initial stitch of a new series, and one part of the present invention consists of means for drawing off from the thread-supply sufficient thread for such purpose.

The needle-bar is shown provided with a laterally apertured take-up arm 68 through which the thread is normally led from the tension device 69 sustained by the bracket 70 upon the top of the tubular arm 3. Se-

cured also upon the bracket is a forwardly extending arm 71 having a threadguiding cross-member 72 which in practice may have an elongated thread-aperture formed therein.

Journaled upon the bracket 70 concentrically with the tension device 69 is an angle-lever formed with a forwardly extending arm 73 having at its extremity an apertured lateral ear 74 and provided with an upwardly extending arm 75 connected by the link 76 with the upper arm 77 of a rock-lever fulcrumed upon the stud-screw 78 and provided with the depending arm 79 having a lateral nose adapted for engagement with the stepped cam-plates 80 secured by screws 81 upon the periphery of the controlling cam 30. The rock-lever is maintained with the nose of its lower arm in contact with the periphery of the cam 30 and cam-plates 80 by means of a spring 82. The cam-plates 80 are so arranged and proportioned that during each of the last several stitches of a group or succession the rock-lever 77 79 is shifted slightly so as to lift the thread-arm 73 progressively until at the completion of the final stitch it assumes the dotted line position represented in Fig. 1, the take-up member 68 serving, not only to set the stitch in performing its normal function, but to draw an excess of thread from the thread-supply through the tension proportionately with each upward step of the guide-member 7 4 until an amount is provided sufiicient to compensate for the severing of the thread beneath the work. In the operation of th machine for the initial stitch of a succeeding group, the nose of the rocklever arm 79 rides down the inclined higher end of the cam-plate and causes the lowering of the thread-arm 73 to initial position in a single step, thereby providing slackthread to enable the first thread-loop presented by the needle to be seized and distended by the looper without having the thread end drawn through the fabric and the loop thus destroyed by action of the take-up. In this stage of the initial stitchforming cycle, the slack thread provided intermediate the needle and the tension de-- vice robs the take-up arm of its normal action in tightening the thread leading from 'action.

the needle-eye to the work, and its action is thereby made ineffective in the same manner as would be the case were its movement actually temporarily suspended.

It is obvious from the foregoing description that the present invention is not limited to the specific mechanism herein shown and described for actuating the thread-severing implement, the thread-nipper orthe slackproducing element, and that these elements are not restricted to use in machines of any particular type or in connection with stitchforming mechanism of any particular class. It is evident that, in case the thread-severing means is employed in conjunction with lock-stitch mechanism, such aS that of the said Patent No. 777,564, some means such as that disclosed in said patent may be used,

in lieu of the chain-stitch. looper of the present mechanism, for detaining the final needle-thread Loop preparatory to the severing action in the position of the various parts corresponding with the retraction of the needle to its highest point, or normal stopping position.

While the operative portion 38' of the thread-severing implement is adapted to be sharpened so as to make a clean cut, as before indicated, it is represented in the drawings blunt-edged so as to be capable of severing the needle-thread loop by a tearing Regardless, however, of the character of the work-engagingporti/on of the severing implement, its positive action upon the thread is insured by the employment of the thread-nipper. V c

Having thus set forth the nature of the invention, what I claim herein is:-

1. In a sewing machine, the combination with stitch-forming mechanism comprising a needle and a cooperating loop-taker, of a thread-nipper, a thread-severing device operated independently of the threadnipper and adapted for engagement with the needle-thread intermediate the needle and the loop-taker, and operating means for causing the thread-nipper to nip the needle-thread and for simultaneously causin the severing device to sever the needlethread-nipper to nip the needle-thread and jfor simultaneously causing the severing device to sever the needle-thread.

3. In a sewing machine, the combination with stitch-forming mechanism comprising a reciprocating needle and a cooperating loop-taker adapted to detain needlethread loops while the needle is out of the work, of a thread-nipper, a thread-severing device operated independently of the thread-nipper and having an implement adapted to engage the thread intermediate the needle and the loop-taker, and operating means for causing the thread-nipper to nip the needle-thread. and for simultaneously causing the severing device to sever the needle-thread.

4. In a sewing machine, th combination with work-supporting means and stitchforming mechanism comprising a reciprocating needle and a cooperating loop-taker adapted to detain needle-thread loops while the needle is out of the work, of a threadnipper disposed at the side of the worksupporting means farthest from the loop taker, a thread-severing device having an implement adapted to engage the thread in termediate the needle and the looptaker, and operating means for causing the threadnipper to nip the needle-thread and for simultaneously causing the severing device to sever the needle-thread.

In a sewing machine, the combination with stitch-forming mechanism comprising a reciprocating needle and a cooperating loop-taker adapted to detain needle-thread loops while the needle is out of the work, of a thread-nipper, a thread-severing device having an implement adapted to engage the thread intermediate the needle and the looptaker, nipper-actuating means, severing-device actuating means independent of said nipper-actuating means, and a common reciprocatory member for causing the threadnipper to nip the needle-thread and for simultaneously causing the severing device to sever the needle-thread, whereby a section of needle-thread held between the loop-taker and the nipper is severed by said thread-engaging implement.

6. In a sewing machine, the combination with stitch-forming mechanism and a cooperating loop-taker, and a stop-motion therefor including a rotary cam and a vibratory lever adapted to engage the same, of a thread-nipper, a thread-severing device having an implement adapted to engage the thread intermediate the needle and the looptaker, and connections between said lever and the nipper and severing device, respectively, for causing them to simultaneously engage the needle-thread.

7. In a sewing machine, the combination with stitch-forming mechanism, actuating means therefor, and a stop-motion including a rotary shouldered cam operatively connected with said actuating means, and a vibratory lever movable into, out of and within the range of action of said cam, of a thread nipper, a thread-severing device having an implement adapted to engage the thread intermediate the needle and the loop-taker, and connections between said lever and the nipper and severing device, respectively, where by lateral movements imparted to said lever by said cam are communicated to the nipper and severing device for their simultaneous nipping and severing action upon the thread.

8. In a sewing machine, the combination with stitch-forming mechanism comprising a needle and a cooperating loop-taker, controlling means for determining the period of action of the stitch-forming mechanism, and a needle-thread take-up, of a thread-cutting device, actuating means therefor controlled by the said controlling means, and meansacting to form slack in the needlethread whereby the take-up is rendered ineffective for normal action upon the needlethread in the stitch-forming cycle immediately succeeding a thread-severing action.

9. In a sewing machine, the combination with stitch-forming mechanism comprising needle and a eoiiperating loop-taker, controlling means for determining the period of action of the stitch-forming mechanism, a needle-thread tension, and a take-up acting upon the needle-thread intermediate said tension and the needle, of a thread-cutting device, actuating means therefor controlled by the said controlling means, and means acting near the completion of the final stitch. preceding a thread-severing action for drawing oiii a supply of thread between the tension and the needle and releasing the same to produce slack in the stitch-forming cycle nextsucceeding said thread-severing action.

10. In a sewing machine, the combination with stitch-forming mechanism comprising a needle and a cooperating loop-taker, controlling means for determining the period of action of the stitch-forming mechanism,

' a needle-thread tension, and a take-up acting upon the needle-thread intermediate said tension and the needle, of a thread-cutting device, actuating means therefor controlled by the said controlling means, and means acting during a succession of stitch-forming cycles immediately preceding each cutting action in drawing ofi a supply of thread between the tension and the needle and for releasing the same to produce slack in the stitch-forming cycle next succeeding said thread-severing action.-

11. In a sewing machine, the combination with stitch-forming mechanism comprising a needle and a cooperating loop-taker, controllin means for determining the period of action of the stitch-forming mechanism,

a needle-thread tension, and a take-up acting upon the needle-thread intermediate said tension and the needle, of a needle-thread cutting device, needle-thread nipping means, actuating means for simultaneously operating the nipping means and cutting device, and means actingbefore the completion of the final stitch preceding a thread-severing action for drawing off a supply of thread between the tension and the needle and releasing the same to produce slack in the stitch-forming cycle next succeeding said thread-severing action. 12. In a sewing machine, the combination with titch-forming mechanism comprising a needle and a cooperating loop-taker, a needle-thread tension, a take-up acting upon the needle-thread intermediate said tension and the needle, and a stop-motion comprising a rotary cam and a vibratory lever adapted to enga e the same, of a needlethread cutting d vice, needle-thread nipping means, actuating means for said nipping means and thread-cutting device connected with and actuated by said vibratory lever, slack-thread producing means operatively engaging the needle-thread intermediate the tension and the needle preparatory to a cutting action and releasing the same in the stitch-producing cycle succeeding said cutting action, and a controlling cam provided with stop-motion tripping means and with means for operating said slack-thread controlling means.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

ALBERT F. FIFIELD.

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