Patent GB-642739-A (GB)
Title: Improvements in or relating to method and machine for stitching or sewing
IPC: D05B1/06
Filed: 1947-07-16
Abstract: 642,739. Sewing; sewing-machines. LION MANUFACTURING CORPORATION. July 16, 1947, No. 18952. Convention date, March 8, 1940. [Class 112] Stitches.-Stitches are made by drawing through the work successive loops of thread, each loop passing through the preceding loop and alternate loops, or loops in some other sequence, being taken from different threads. The loops may vary in length, so that the long loops will lock the short ones. A seam of this kind is shown in Fig. 17, which shows how the freeing of one long loop does not free the preceding loop. Stitch-forming devices.-A barbed needle H, Fig. 3, is fixed to a needle-bar 1, driven by a crank with variable throw, and is provided with a slidable hook-closing pin J with a head 29. A looper O is carried by a fixed spring stem P and provided with two eyes o to receive two threads from reels L ; the looper has an aperture to receive the needle and an inclined V-section face for engagement by the feed-claw F. The threads pass to the looper through guides 59, Fig. 5, in the ends of a slidable looperpositioning member M with a central cam portion N, which may be supplemented by an anti-friction roller 64, to deflect the looper to one side or the other when it is pressed back by the feed-foot. The member M may be held in either extreme position by one of two slidable stops 72. The manner of operation is described below. Feed.-The feed-claw F is carried by a member 31 formed with wings 36 to embrace the variable-stroke needle-bar 1 and with abutments 32, 33, 35 for engagement respectively with the lower end of the needle-bar, a shoulder on the needle-bar, and an adjustable upper stop (not shown). The member 31 is pressed against the needle-bar by a spring 38 fixed to the latter; this spring assists in the operation of the claw, as described below. Work-supports.-The work-plate G slopes downwards from the needle-hole, and has an aperture 55 through which the feedclaw F can press the work against the looper O. Operation.-From the position shown in Fig. 3 the needle-bar 1 carries down with it the feed-member 31, and the wings 36 on the latter move the pin J down with it until the head 29 meets an abutment 40; on further movement of the needle-bar, the member 31 is forced to the left, by cam surfaces on its wings 36 and by the claw F moving down the slope of the work-plate G, to disengage the abutments 32, 33 from the needle-bar, and the needle-hook is opened to allow the existing loop to pass up the needle. Before the needle descends as far as the looper O, the latter is pushed back by the feed-claw F against the cam N of the positioning member M and is deflected to one side by this cam so that the needle enters at one corner of the triangular aperture in the looper, as shown dotted in Fig. 6, and both threads lie on the same side of it. The feed-claw is then pressed aside, clear of the looper by the needle-bar, and allows the looper to return to its original position, in which the needle is in the middle corner of its aperture and one thread is engaged in the needle hook; the head of the pin J is then carried over the abutment 40 by the upper end of a recess 30 in the needle-bar to close the hook. When the needle-bar rises the feed member 31 is lifted with it by the spring 38, the lower end of which has passed below the step 32, until it is stopped by the abutment 35 engaging its stop, whereafter the needle-bar rises further to the position shown, the hook remaining closed. The tension in the thread drawn up by the needle causes the member M to move across (unless held by the member 72) so that in the next cycle the looper will engage the other side of the cam N to bring the other thread into position for engagement by the needle. Loops of different lengths are produced in the respective threads by subjecting the latter to different tensions. Thread-spool holders.-The thread reels L lie freely in cylindrical recesses in the base C of the machine, being located by bosses on the housing and on a hinged access door 66. The threads pass through slots 65 in the sides of the recesses, and the reels are normally placed so that the thread unwinds from beneath them. If a reel in inverted, as shown in Fig. 3, the thread is bent sharply round the edge of the slot 65 and its tension is thus increased by the additional friction. Presser-bars. - The presser-foot E is carried by a vertically-slidable member provided with a weight 49 to hold it down.