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Patent US 2070029 A: Thread-cutter for sewing machines

Thread-cutter for sewing machines

Patent Number: US 2070029 A
Filing date: Oct 4, 1935
Publication date: Feb 9, 1937

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Feb. 9, 1937. P. SPAINE THREAD CUTTER FOR SEWING MACHINES Filed Oct. 4, 1955 6 Sheets-Sheet l mime/x1 Feb. 9, 1937.

E. P. SPAINE THREAD CUTTER FOR SEWING MACH INES 6 sheets sheet 32 Filed 001;. 4, 19 35 Feb. 9, .1937. E. P. SPAINE THREAD CUTTER FOR SEWING MACHINES F led oat. 4. 1955 6 Sheets-Sheet 3 Edward 1. xs oaz'ne Wibma Feb. 9, 1937. E. P. SPAINE 2,070,029

THREAD CUTTER FOR SEWING MACHINES Eiled Oct. 4; 1935 e Sheets-Sheet 4 Feb. 9, 1937. E. P. SPAINE I THREAD CUTTER FOR SEWING MACHINES Filed Oct. 4, 1935 6 Sheets-Sheet 5 WMWveow y Feb. 9, 1937. E. P. SPAINE THREAD CUTTER FOR SEWING MACHINES Filed Oct. 4, 1935 6 Sheets-Sheet 6 Edward 1? Sjmu'ne Patented Feb. 9, 1937 UNITED STATES PATENT OFFICE THREAD-CUTTER FOR SEWING MACHINES Application October 4, 1935, Serial No. 43,467

9 Claims.

This invention relates to thread-cutting mechanisms for sewing machines and more particularly to thread-cutting mechanisms for machines of the buttonhole sewing type having stitch-forming mechanism and a work-clamp with means for relatively moving the stitch-forming mechanism and work-clamp after the sewing of the buttonhole has been completed to draw out a length of thread from the needle-throat member at the under side of the work; means being provided to separate the drawn out thread or threads from the work and to out such thread or threads close to the last stitch.

The invention aims to improve the thread-cutting mechanism disclosed in the U. S. patent to E. B. Allen, No. 1,579,200, dated Apr. (3,1926, so that it will handle work of any texture without damaging the work. In the mechanism of the Allen patent there is provided a scissors device for cutting the thread, which scissors device is moved along an upwardly arched path transversely of the thread-lengths to be cut and substantially tangent to the under surface of the work, so that the blunt point or noseof the upper scissors blade will graze the under surface of the work and enter between such surface and the threads to be cut, deflecting the threads downwardly into the throat of the scissors.

The setting or adjustment of the operative radius of the scissors device of said patented construction is rather critical as, if too short the blunted point of the upper scissors blade is not likely to catch all of the threads and cord to be cut and, if too long, there is danger that the point, even though blunted, will snag the work, particularly if the latter is of a loosely woven or knitted, sleazy or spongy nature.

According to the present improvement, the nose of the upper scissors blade is made of special shape so that it cannot possibly snag the work but will safely graze the latter and catch the threads to be cut, regardless of the character of the fabric in which the buttonhole is stitched. The principal characteristic of the nose of the present device is its broad, flat, duck-bill or spatula shape affording a thin and dull leading edge which is rounded horizontally along a broad-curve so that it can safely graze the spongiest and sleaziest work without catching the fibres of the work.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

The invention will be better understood by reference to the following detailed description of certain specific embodiments of the invention shown in the accompanying drawings, in which Fig. 1 is a side elevation of a buttonhole sewing machine embodying the invention. Fig. 2 is a fragmentary front elevation of the machine. Fig. 3 is a plan view of the machine bed with the work-clamp removed. Fig. 4 is a plan View of the work-clamping elements and thread-cutting device, showing the nose of the latter entering between the threads to be cut and the under surface of the work. Fig. 5 is a section substantially on the line 5-5, Fig. 4. Fig. 6 is a fragmentary plan view of one of the lower auxiliary worksupporting plates of the work-clamp. Fig. 7 is a section substantially on the line 7-4, Fig. 4. Fig. 8 is a bottom or under side view of the thread-cutter of Figs. 1 to 7, inclusive. Fig. 9 is a side view of the thread-cutter opposite to that shown in Fig. 2. Fig. 10 is a disassembled perspective view of the thread-cutter of Figs. 1 to 9, inclusive.

Figs. 11, 12, and 13 are, respectively, side elevation, bottom plan and disassembled perspective views of a modified form of thread-cutter. Figs. 14, 15, and 16 are, respectively, side elevation, top plan and disassembled perspective views of another modification of the thread-cutter, and Fig. 17 is a section on the line I'l-ll, Fig. 14.

The machine is constructed with a frame having a bed I from which rises the standard 2 of the bracket-arm 3 terminating in the head 4.

The stitch-forming mechanism comprises the usual upper endwise reciprocatory and laterally vibratory needle 5 which cooperates with the under stitch-forming instrumentalities carried by the rotary turret 6; such under instrumentalities including the usual threaded and non-threaded loopers, l and 8, respectively, and the loopdetainers 9 and I0; being constructed substantially in accordance with the disclosure of the U. S. Patent to Allen et al., No. 1,372,473, dated Mar. 22, 1921. The turret 5 carries the usual needlethroat member ll having the needle-receiving aperture l2 and the usual means for guiding the stay cord l3 which is incorporated within the buttonhole overseam at the under side of the work.

The stitch-forming mechanism is operated from the sewing shaft I 4 at the rear end of which 5 5 is the usual belt-pulley l 5 and stop-motion device which is constructed substantially in accordance with the disclosure of the Allen Patent No. 15,324; reissued Apr. 4, 1922, and includes the tilting stop-motion lever [B which is fulcrumed at IT and carries the stopping tooth i8 adapted for cooperation in a manner well known with the stopping cam I9 on the shaft 14.

Within the bed I is mounted the usual feedwheel 20 which makes one complete rotation per buttonhole-prcducing cycle and is driven during the sewing portion of such cycle by a suitable one- Way gear-driven connection (not shown) with the upright shaft 2! driven by the bevel gear connection 22, 23 with the sewing shaft I 4. The feedwheel is connected to be driven at a higher speed both prior and subsequent to the sewing period by the usual automatically operated clutch (not shown) intermediate the constantly running shaft 24 and the rapid-feed shaft 25, which latter is permanently geared at 26 to the feed-wheel 20.

The work-clamp, which has the usual operative connections with the feed-Wheel 20, comprises the lower work-supporting plates 27 and upper pivotally mounted clamping feet 28 sustained by the respective clamp-levers 20 fulcrumed at 3B. The work-clamp is closed automatically at the beginning of a buttonhole-producing cycle by a single oscillatory movement of the usual clampclosing lever 3! which engages the arm 32 on the clamp-closing rock-shaft 33, as explained in said Allen reissued patent. As soon as the workclamp is closed, the feed-wheel 20 and rapidfeed shaft 25 are coupled to the rapid-drive shaft 24, whereby the work-clamp is rapidly shifted forwardly from its initial position on the bed i to sewing position. When the work-clamp reaches sewing position the rapid-feed drive-shaft 24 is unclutched from the rapid-feed shaft 25 and the stitch-forming mechanism is started, whereupon the feed-wheel 20 and rapid-feed shaft 25 are more slowly driven through the usual gear-connections with the sewing shaft l4 and the work is moved in the usual path to space the stitches around the buttonhole. During the sewing around the eyelet end of the buttonhole the stitch-forming mechanism is slowly turned 180 about the vertical axis of the turret 5. When the sewing of the buttonhole is completed the stopmotion lever 15 is tripped to stop the sewing shaft l4. The feed-wheel and rapid-feed shaft 25 are then again connected to the rapid-feed driveshaft 24 which operates to rapidly shift the workclamp rearwardly from sewing position to the initial or buttonhole-cutting position on the bed I which movement of the work-clamp draws out from the needle-throat member H four thread lengths in close juxtaposition. One of these thread lengths is the stay-cord 13. Another is the looper-thread 34. The remaining two are the limbs of the last needle-thread loop 35 retained on the loop-detainer 9 when the machine comes to rest.

In the U. S. patent to Allen, No. 1,579,200 cited, and in U. S. patents to Allen Nos. 1,600,206, of Sept. 21, 1926; 1,711,483, of May 7, 1929; 1,852,-

634, of Apr. 5, 1932; 1,867,129, of July 12, 1932; and

in the U. S. Patent to Wood No. 1,938,128, of Dec. 5, 1933, there are disclosed scissor devices for severing these drawn out thread-lengths close to the last stitch in the Work. The device of the present invention is broadly similar in principle and mode of operation to that of the Allen Patent No. 1,579,200. It comprises the usual threadcutter-carrying lever 36, Fig. 2, which is fulcrumed on the stud 31 and is connected by the link 38 to the arm 39 of a lever fulcrumed at 40 and having an arm 4|, Fig. 1, which has a rollerstud 42 entering the thread-cutter-actuating cam-slot 43 in the gear 26 on the rapid-feed shaft 25; the connections described being substantially the same as shown and described in said U. S. Patent No. 1,600,206, and the subsequently issued patents above cited.

The lever 30 carries the thread-cutting device including a supporting shank 44, Figs. 8 and 9, carrying a fulcrum-stud 45 on which is mounted the upper and lower blades 46, 47 of the scissors. The upper blade 45 has a tail portion 48 which carries a screw 49 passing through a slot 50 in the shank 45. By loosening the screw 49 the upper blade 56 may be adjusted about the fulcrumstud 45 to adjust the radius of action of the thread-catching point of the blade. The lower blade 41 has the usual lateral stud 5| which enters the groove 52 of the stationary scissors-closing and opening cam 53.

In the device of the U. S. Patent No 1,579,200, the upper or ledger-blade of the scissors is formed with a dulled and rounded leading point so that it will not catch the fibres of the work while grazing the latter. In accordance with the present improvement this pointed end has been eliminated and the nose given a spatulate or duckbilled form by being considerably widened at one side of the vertical cutting plane of the scissors and formed with a broadly curved leading edge which may safely graze the under surface of work of any texture without catching the fibres thereof.

As shown in Figs. 7 to 10, inclusive, this spatulate or duck-billed-shaped nose of the upper blade of the thread-cutter is constituted by a separate element 54 having an attaching shank 55 similar'to the shank 48 of the upper blade 46 of the scissors and attachable with the latter to the thread-cutter support 44 by the pivot-stud 45 and holding screw 49.

The point 56 of the upper blade of the scissors is in intimate contact with the under surface of the spatulate member 54, so that the threads caught by the advance of said member 54 readily slip under the point 56 and into the throat of the scissors. The member 54 is only made separate from the blade 45 for convenience. Functionally it is integral with the blade 46. The spring 51 holds the lower scissors blade 41 in working contact with the upper, or ledger-blade 45. The broadly curved and dulled leading edge of the spatulate nose of the upper thread-cutter blade is preferably shaped as shown in Figs. 4 and 8. portion 58 is widely spaced from the vertical cutting plane of the thread-cutter and is connected by an inclined portion 59 of gradually decreasing radius of curvature leading to the side edgeportion 55, Figs. 4 and 8, which latter is in line with the end of the buttonhole after the work has been shifted from sewing position to initial position and the threads to be out have been drawn out from the needle-throat member I l, as usual, by such shifting of the work.

The lower clamp-plates 21, 2'! are provided with thread-cutter clearance apertures a to permit the thread-cutter to move along its upwardly arched path grazing the under surface of the work.

To dress up the machine, it is preferred to partially cover these apertures a and to this end there are provided a pair of cover-plates 6| attached to the lower clamp-plates 21 by screws 62.

Its broadly curved foremost or leading The cover-plates 6| are thin and expose the under surface portion of the work directly over the needle-throat member H. The upper clamp-feet 28 may be provided with spring toe extensions 65 to press the work upon the cover-plates 6! in the regions thereof at the sides of the needlethroat-member ii. The broadly curved tip end 58 of the nose 54 of the thread-cutter preferably passes over the needle-throat-member I l and the threads issuing therefrom, and under the portion 63 of the work in front of the buttonhole 64. The inclined portion 59 of the nose 54 carries the separation of the threads from the work up close to the last stitch 65 where the threads are subsequently out by closure of the scissors in the usual manner. The fully advanced position of the thread-cutter nose 54 is shown in dotted lines in Figs. 4 and 7. The threads are out, however, before the thread-cutter reaches. the end of its advancing movement; the closure of the scissors being effected by the inclined upper end of the stationary cam-slot 52, Fig. 2, in the usual manner disclosed in U. S. Patent No. 1,579,200, previviously referred to.

It is to be understood that the use of the cover plates BI is not essential to the functioning of the present thread and work-separating nose 54 of the thread-cutter, as the device functions just as well in the absence of the cover-plates 6!; the duck-bill or spatulate nose 54 scraping the threads I3, 34, and 35 from the under surface of the work without the slightest danger of catching the threads or fibres of the work.

The thread-gripper 61 seizes and removes the severed or waste loop 35 of needle-thread which is around the loop-detainer 9 when the machine comes to rest. This thread-gripper is preferably constructed and operated substantially in accordance with the disclosure of said U. S. Patent No. 1,579,200. After the threads are cut, the threadcutter is retracted to its normally out-of-the-way position, Fig. 2.

In Figs. 11, 12, and 13 there is illustrated a modified construction 68 of the duck-bill shaped member. Its shape, in plan is substantially the same as that of the first described member 54. It differs from the first described member 5a in that it does not overlie the point of the upper scissors blade 46', Fig. 13, but has a downturned fiange 69 against the side face ll of which the point II of the blade it bears. The flange 69 guides the threads downwardly onto the point TI and into the throat of the scissors.

In Figs. 14 to 17, inclusive, there is illustrated a further modification of the present improvement. The thread-cutter supporting shank it has mounted thereon the duck-bill shaped member 12 having substantially the same shape, in plan, as the previously described members 54 and 68 but differing therefrom in being formed adjacent its inner edge 13 with a slot M into which extends the sharpened upper curved edge 15 of the knife 16 which is secured rigidly to the support 44 by the screws T5, T8 affording the usual adjustment of the working radius of the thread-cutter. The nose l2 acts to separate the threads from the under surface of the work in the same manner as do the noses 54 and 58 of the previously described modifications.

It will be understood that near the close of a buttonhole-producing cycle and after the workclamp has been rapidly shifted rearwardly to the position shown in Fig. 4 to draw out the lengths of thread from the needle-throat-member i i, the hump in the thread-cutter operating cam 43 in the gear 26 on the rapid-feed shaft 25-effects a single up-and-down vibratory movement to the lever 39 which rocks the thread-cutter carrying lever 36 about its fulcrum 31 and advances the thread-cutter along its upwardly curved path in a direction transverse to the thread-lengths to be cut. The operating radius of the duck-bill shaped nose of the thread-cutter is adjusted to graze fiatwise of itself the under surface of the work and pass over the needle throat-member H and the threads issuing therefrom. The inclined edge 59 and side edge 60 of the threadcutter nose effects a separation of the threads from the work at a point close to the last stitch where the threads are cut by the thread-cutter. It is of course understood that the pivotal axis 37 of the thread-cutter substantially intersects a vertical line normal to the work at the sewing point. In other words the thread-cutter axis 31 is directly under the sewing point, as viewed in Fig. 2, so that the threads to be out are at the top of the curved path of travel of the threadcutter.

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

1. In a sewing machine in which that portion of the thread to be cut extends along and close to the surface of the work, means having a spatula shaped nose movable in a direction transverse to the thread-length and between the thread and the surface of the work to separate the thread from the Work at a point close to the last stitch, and means to out said thread close to the last stitch.

2. A sewing machine having, in combination, stitch-forming mechanism including a reciprocatory needle and complemental loop-taking means mounted at opposite sides of the plane of the work, a thread-cutter-carrying lever pivoted at the loop-taker side of the work on an axis transverse to and in substantially intersecting relation with a line normal to the plane of the work at the sewing point, and a thread-cutter carried by said lever and having a spatula shaped nose adapted when said lever is swung on its pivot to enter fiatwise of itself between the under surface of the work and the thread leading from the last stitch to the sewing point, to separate the thread from the work close to the last stitch preparatory to the severing of the thread by the thread-cutter.

3. A buttonhole sewing machine having a frame comprising a bed and bracket-arm, stitch-forming mechanism including a needle and a needlethroat member, a work-clamp, means for relatively moving the stitch-forming mechanism and work-clamp to sew around a buttonhole and to relatively separate the buttonhole and stitchforming mechanism lengthwise of the machine bed subsequent to the sewing operation, thereby drawing out a length of thread from the needlethroat member, and a thread-cutter pivoted on an axis extending lengthwise of the machine bed, said thread-cutter having a thin spatula shaped nose adapted to scrape the thread from the under surface of the work and separate the thread from the work close to the last stitch preparatory to the thread-cutting action.

4. In a sewing machine adapted to perform a predetermined sewing operation and then come to rest, the combination with stitch-forming mechanism and work-holding means movable relative to each other during and subsequent to a relative movement after the sewing operation drawing out a length of thread from the needlethroat member, means movable over the needlethroat member in a direction transverse to the length of thread to a position between the length of thread and the work, said means having a broadly curved leading edge, and means to sever the thread close to the last stitch. V

5. In a sewing machine adapted to perform a predetermined sewing operation and then come to rest, the combination with stitch-forming mechanism and work-holding means movable relative to each other during and subsequent to the sewing operation, of a needle-throat member through which the thread is led to the work, the relative movement after the sewing operation drawing out a length of thread from the needlethroat member, of means movable transversely of the length of the thread and having a thin and wide nose with a broadly curved and non-pointed leading edge to separate the thread from the work close to the last stitch, and means to sever the thread.

6. In a sewing machine adapted to perform a predetermine sewing operation and then come to rest, the combination with stitch-forming mechanism and work-holding means movable relative to each other during and subsequent to the sewing operation, of a needle-throat member through which the thread is led to the work, the relative movement after the sewing operation drawing out a length of thread from the needle-- throat member, of means movable in a curved path transversely of the length of thread and having a thin wide nose with a broad tip and an inclined edge leading from said tip to separate the thread from the work close to the last stitch, and means to sever the thread.

7. In a sewing machine adapted to perform a predetermined sewing operation and then come to rest, the combination with stitch-forming mechanism and work-holding means movable relative to each other during and subsequent to the sewing operation, of a needle-throat member through which the thread is led to the work, the relative movement after the sewing operation drawing out a length of thread from the needlethroat member, means movable transversely of the length of thread and having a thin wide nose with a broadly curved tip and an inclined edge portion leading from said tip to pass between the thread and the work, and means to sever the thread;

8. A sewing machine thread-cutter having a thread-cutting blade and a thin wide nose substantially normal to the cutting plane of said blade; the extreme end of said nose being broadl curved in the plane thereof.

9. In a sewing machine adapted to perform a predetermined sewing operation and then come to rest, the combination with stitch-forming mechanism and work-holding means movable relative to each other during and subsequent to the sewing operation, of a needle-throat member through which the thread is led to the work, the relative movement after the sewing operation drawing out a length of thread from the needlethroat member, of thread and work-separating means having a thin, broadly curved and nonpointed leading edge movable transversely of the thread and between the latter and the work, and means to sever the thread.

EDWARD P. SPAINE.

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