GB1103089A - Thread handling systems and devices for sewing machines - Google Patents

Abstract

1,103,089. Sewing machines. SINGER CO.23 Jan., 1967 [10 Feb., 1966], No. 3313/67. Heading D1G. Thread passes from a supply to the stitchforming means of a sewing machine through a conduit, and air under pressure is caused to flow through the conduit contrary to the movement of the thread for tensioning the latter to set the stitches. In one embodiment the needle bar 28 of a lockstitch sewing machine is slidable in a bush 27 formed with diametricallyopposed apertures 31, 32. Aperture 31 is connected via a tube 34 and an on/off valve 35 to a compressed air main 36. Aperture 32 is connected via a tube 37 to an aperture 46 in the head of a casing 41 communicating with the space between two depending walls 43, 44. A second aperture 50 communicating with said space is provided in said head. Thread 62 from a cop 61 passes successively through a tensioner 60 and the apertures 50, 46 to enter tube 37, emerging from the latter through an outlet 40 adjacent the sewing machine, and finally passing to the needle 29. The needle bar is formed with a transverse bore 33 which becomes aligned with the apertures 31, 32 during the upstroke, when a loop of thread seized by the beak 67 of a rotary hook 63 is in the cast-off position. Air then flows through tube 37 to tension thread 62, thereby setting the stitch, while the resultant slack thread forms a loop 42 in the space beween the walls 43, 44. To facilitate thread pull-off, the loop-controlling tail 75 is shorter than usual, and a second thread guide 79 is mounted on the usual thread guide 78 to prevent beak 67 from picking up a double loop. In a modification, Fig. 4, a simple bent pipe (91) is used and casing 41 is omitted. In another embodiment, threads 135, 136 pass through tensioners 142, 143 and bent tubes 131, 132 to a closed casing 137, emerging from the latter by outlets 138, 139, and finally passing to the respective loopers 125, 126 of an overedge sewing machine. A compressed air main 141 is connected to an inlet 140 of casing 137, whereby the passage of the air in the pipes 131, 132 serves to tension the looper threads. In a two-thread chain stitching machine, thread to the single looper (114), Fig. 9, passes through a bent tube (117) through which a counter flow of compressed air is induced, the thread passing around a snubbing post (123) at the entrance of tube (117).