US944740A - Sewing-machine. - Google Patents

Description

l- `A. L. MADISON.

SEWING MACHINE. APPLICATION FILED 1330.1, 1905. Y

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frz vewgn Patented Dec. 28, 1909.

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ALFRED L. MADISON, OF BROOKLYN, NEI/V YORK, ASSIGNOR TO WILLCOX & GIBBS .SEWING MACHINE COMPANY, OF NEW YORK, N. Y., A CORPOBATIONOF NEW YORK.

SEWING-MACHINE.

path of the point of the rotating hook or in' the path ot' the descending needle, as enagement ofthis thread by the hook or its impalen'ienton the point of the needle both result in cutting or breaking the thread. In the ordinary` running of such machines, this portion of the bobbin-thread is held .taut and cannot assume such objectionable positions.' Butwhen the machine is caused to perform' operations such as tacking or chaining elim? (more fully explained vhereinafter) there is a slackening of the lower thread tending to cause the portion thereof extending from the bobbin-case to' the work to assume the objectionable position above mentioned. By my invention4 I obviate the difficulty by providing` special means which prevent the slackened thread from assuming the objectionable position. These means may be most conveniently explained in conjunction with the accompanying` drawings, in which- Figure 1 is a perspective view of a bobbincase ei'nbodying the invention; Fig. 2 is a plan view showing a portion ot' a rotary i hook, the bobbincase and a portion of the bobbimcase hanger, all in operative relation; Fig. 3 shows the`work-plate and thev work in vertical section longitudinal to the line of feed, and the bobbin case and hook in elevation from the left in Figs.v 2 and 4, the parts thus shown being in relative operative positions; and F ig. 4 is a vertical sectional view on line 4, Fig. 3, showing also the bobbin-case hanger in elevation.

-Ilxcept for the means constituting my invention, the parts shown in the drawings are substantially the same as the corresponding parts of U. S. patent to Stockton Borton, No. 572,090, dated Nov. 24, 1906, to which reference may be made' for a detailed description thereof.

io (riga) is uw hook-Shift 'which in the Specification of Letters Patent.

' to afford room for the PatentedDec. 28, 1909.

Application filed December 1, 1905. Serial No. 289,808.

type of machine illustrated is organized to receive three revolutions to every one of the main shaft; consequently the rotary cupshaped hook 11, xcd on the end of the shaft, makes three revolutions for every complete reciprocation of the needle. But the present invention is not limited to machineshaving these characteristics. The interior of the hook is made slightly larger than the stationary or non-rotatable bobbin-case 12, which contains bobbin 13, so as assa e between the case and' hook of the oop 'ormed in the -needle thread by the act-ion of the hook in making each stitch, it being understood that in a machine in which the hook makes, for example, three revolutions to one reciproca tion of the needle, this action of the hook in forming a loop takes place during only one of its revolutions, the hook being out of engagement with the needle thread during its other two revolutions. The rim Aof the bol bin case 12 is not continuous but is cut away, as best shown ink Fig. 3, leaving three segments, 14, 15 and 16. The cut or notch 17 8O in frontv of one end ot segment 16 is the pas:5 sage or recess into which the needle descends; this notchis made sutliciently deep to afford ample room for the loop of the needle thread to spread out and be engaged by the point 18 of the hook. thread is led from the bobbin through the end of a cut 19 (F ig. 4) in the bobbin case. directly under the tension-spring 20, thence in a thread groove 21 along` the base of segment 15, through a thread eye or guide 22 and thence upward from the bobbin-case in The bobbin an oblique direction (opposite to that of the j rotation of the hook) through the needleA hole 23 in work plate 24 to the work or goods Q5, the latter being represented in the drawing as two pieces Vof fabric to be sewed shoulders which overlie and rest loosely upon 'j the curved` edge of. the disk-.shaped hanger,

as clearly shown in Fig. 2.

A brief reference to the icperation will,

however, further facilitate an understanding 1 1oll tion of the parts here explained, it will be 'dle 32 whihh descends in front of it. -But it follows: In ruiming a lock-stitch seam olf of the present. invention. In the normal position of the parts for stitching, the lower thread 30 extends from thread-eye 22 upward at an angle toward the front of the machine; past the rear curved side 31 of the needle-hole'23, to the goods, as clearly shown in. Fig. 3. VJ hen the feed devices or surfaces (not shown) advance the work in the direction of the arrow, Fig. 3, and also slightly lift it, thread 30 is .pulled tightly around the curved edge 31 of the needle hole, and a certain amount of additional thread required for one stitch is pulled oil the bobhi In this ositionof the parts the lower thread is held taut by the tension-- spring 20, and the needle descending, the needle thread is looped around the bobbin- 1 case by the action of the hook and pulled up against this lower bobbin thread, thus locking the stitch to the work. From the relathat with the lower thread thus ti v drawn against the back or surface 31 of needle hole, there is no danger of its being caught either by the point 1S of hook 11, which 'casses it at one side, or by the nee'- apparent has been found that there is such danger when the work is manipulated to perform operations known as tacking and chaining off or the work for other reason pulled out of its normal position while the machine is stitchiiig. Tackiirg is erformed' as the edge of two o r more superimposed pieces of fabri, it is found that the stitches at the extreme edge are not sufficiently secure to bind or hold the fabrics together and consecj 'a ..,r-.ly in handling and use the connection at this point quickly becomes loose, leaving the pieces of fabric insecurely connected or practically disconnected for short distance. at the end of the seam. The same difficulty is experienced where it is desired to stop the seam in the middle-of two pieces of goods whichvit is desired to securely fasten together up to the very end of the seam. To overcome this objectionv it is customary for operatives to move the wor'k back and forth, eitherin line with the seam or otherwise, so as to form a succession or cluster of stitches, either over the edge or within 1the body of the goods, and either superimposed or side by side. 'This operation is called tacking Diiliculty is'frequently experienced in performing this operation in machines heretofore used for the reason that the extraordinary movements given the goods, back and forth or sidewise, produce slack in the bobbin thread, particularly between the bobbincase and goods, and tend to throT this slackthread in the path of the point 18 of the hook, which catches and. breaks or cuts the thread, or in the path of the needle which impales the thread with resultant' breakage.

Such breaking of the thread of course interrupts and frequently interfereswith the perfect operation of the entire stitch-formmg mechanism, particularly necessitating rethreading of the bobbin-case, and sometimes rethreading of the needle. In Figs. 3 and 4 the last stitch formed is over the edge of the two pieces of fabric, and the needle being elevated, it may be assumed that the operative is moving the oods in the direction opposite that in whic the arrow points, and consequently opposite that in which the goods are normally fed. Instead of leaving the bobbin or lower thread 3() stretched taut around the curved edge 31 of' needle opening 23, and fconsequently where it cannot assume a position in the path of the hook or the descending needle, which are the conditions in the normal operation of the machine, as already explained, this reverse movement of the goods slackens the .lower thread by the amount which was bent around the curved edge 31 of opening 23 in feeding for the last preceding stitch. As already stated, it is possible, and frequently happens in machines not embodyin myV present invention, that this slacke thread, illustrated in Figs. 3 and 4, thus produced by abnormal movement of the work,

will deect-'or depend toward and into the4 path of the point of the hook and be cut by the latter, or be carried under the the needle and impaled thereon. here is a, similar slackening of the under thread with like danger and results, in the operation of chaining off which operation consists in causiner mechanism to form the thread into a sucvcession of stitches after the work or goods have passed beyond the needle. This slackening of the thread may also occur in other manipulations of the work which need not here be detailed. -According to the present invention, the slackened lower thread m such abnormal operations is prevented from assuming either of the injurious and objectionable positions mentioned by providing, between the thread-eye 22 of the bobbin-case, on the one hand, and the paths of the hook and descending needle, on the other hand, a guard or shield which prevents the slack thread from being carried'into or holds it out. of said path. As shown inthe drawing, and in the preferred embodiment of the invention, this guard consists of a thin plate 40, carried by thel bobbin-case and curving in approximately a semi-circle from the upper end of flange 29, across the up er en'd o notch or needle passage 17 to the ackfof thread eye 22, as clearly shown in Figs. 1,'2 and 3. This plate may be soldered or welded to, or formed integral with, the parts to which it is joined. The upper edge of the guard is as high, preferably higher (as clearly shown in Fig. 4),-than the highest oint of or permitting the sewing l 'i particular embodiment described and illusyheretofore explained, between the exit end tlected away from around the patho point of the path of the/point 18 of the hook, and the thread-eye 22 is so constructed and positionedthat the upper or exit end of its opening is below the upper edge of the guard. lhen the thread is slackened, as

of the'threadfeye and itspoint of connection-to thelwork, it bears intermediate of these points against' the upper edge of the guard and is thereb held, spread or de-Q t e path of the hookpoint so that it, cannot possiblycome in contact with the hook oint as the latter passes. By carrying or bri oing the guard partiall'y the needle across and l above the upper end of notch 17, the slackl cned-thread is also dellected away from and cannot 'be carried into the needle path, and consequently the danger of its being impa ed on the point of the needle is entirely obviated.

The invention is clearly not limited to the g trated.

What is claimed..x is; 1. In a lock-stitch sewing machine, the l combination of a rotary hook, a cooperating l needle, a stationary bobbin case having at i i one sidethereof atits outer edge a passage into which the needle descends, a guard on the bobbin case bridging across said needle passage, and a thread-eye 'or guide on the bobbin casehaving its exit end below the upper edge of said guard whereby the bobbin thread extends upward to the work past said guard.

2. In a lock-stitch sewing machine, the combination of a rotary hook, a coperating needle, a stationary'bobbin case having at one side thereof at itsouter edge a passage into which the needle descends, a guard consisting of a plate or wall bowed or curved outward around the passage into which the needle descends and joining the bobbin case at its 'opposite ends, and a thread-eye or guide ou the bobbin case having its exit end below the upper edge of said guard whereby the bobbin thread extends upward past said guard to the work.

-In testimony whereof I have signed this specification in the presence of twosubscrib- ALFRED L. MADISON.

ing witnesses.

` Witnesses: J AHIAL PAMoLY,

.WALLACE C. PAUL.

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