GB1098320A - Bobbin thread replenishing programming mechanisms for sewing machines - Google Patents

Abstract

1,098,320. Sewing machines. SINGER CO. Oct. 19, 1966 [Oct. 23, 1965], No. 46651/66. Heading D1G. A sewing machine with means for replenishing a bobbin with thread in situ in the looptaker has a bobbin thread replenishing programming mechanism comprising a plurality of timing means adapted to be connected successively and recurringly to the bobbin thread replenishing means to determine the length of thread to be replenished, indexing means for automatically introducing the timing means successively and recurringly, means for operatively connecting to the replenishing means that one of the timing means so introduced, and manual means for connecting said connecting means to said introduced indexing means. An arm shaft 17 is operatively connected by a vertical shaft 78 to a bed shaft 79 driving the looptaker 21. Winding of the bobbin in situ with needle thread is initiated by imparting longitudinal movement to a rod 90 slidably mounted within shaft 29 and by running the machine. A sleeve 27, rigid with shaft 17, has a screw-threaded portion 28 adapted to cooperate with a screw-threaded portion 29 on one arm of a double arm lever 30 pivoted at 32 to a block 31 slidable on rods 37, 38 and biased towards sleeve 27 by springs 42. A double arm lever 43, pivoted at 44, has one arm pivoted at 69 to a vertical rod 68 biased downwardly by a spring 108 to engage the other arm with lever 30 for interengaging screw threads 28, 29. The arrangement is thereby such that when the machine operates, block 31 travels away from sleeve 28 until lever 30 is disengaged from the end 45 of lever 43, when a spring 35 acting on the other arm of lever 30 disengages threads 29 from threads 28, and bobbin replenishment is terminated. The amount of replenishment is proportional to the travel of block 31, the initial position of which is determined by the selective engagement of an abutment 39 thereon with one of four screws 25 of varying lengths protruding at 90 degrees apart from a block 22 rigid with a journalled shaft 23. A gear (46) on the latter meshes with a gear 47 rigid with a ratchet wheel (49). A journalled shaft 55 carries at one end a pawl (51) biased by a spring 54 against ratchet wheel (49). The other end of shaft 55 carries a pin (59) engaging a slot 61 in one arm 62 of a bell crank lever 63 pivoted on a shaft 64. The other arm 65 of lever 63 engages a slot in a bar 67 rigid with block 31. The lower end of rod 68 is pivoted on a pin 72, and is rigid with a pin 73 engaging a cam member 77 slidable on shaft 78, the arrangement being such that when rod 68 moves upwardly, cam 77 imparts movement to a horizontally slidable follower 84 for shifting rod 90 to initiate bobbin winding. Pin 72 is carried by the free ends of levers 117 and is connected by a link 120 to a pin 121 on which is pivoted the feed lift pitman 123, and which is connected by a link 126 to a crank 128 on a feed lift shaft 129. The arrangement is such that raising of rod 68 serves to prevent oscillation of shaft 129 for immobilising the feed. To initiate bobbin winding, one arm 102 of a double arm lever pivoted at 103 is depressed, whereby the other arm 104 engages a lug 105 rigid with rod 68 to raise the latter. Thereby rod 90 is displaced, the feed is immobilised, and lever 43 is pivoted counterclockwise, whereby one arm of lever 43 displaces an arm 134 to rotate a shaft 135 for releasing the thread tension at a tensioner 133. The other arm of lever 43 moves clear of lever 30, whereby the springs 42 shift block 31 to engage abutment 39 with the screw 25 aligned therewith. On release of arm 102, lever 43 interengages screw threads 28, 29, and bobbin winding proceeds, when the machine is operated, until lever 30 is disengaged from end 45. During the movement of block 31 away from sleeve 27, bar 67 co-operates with bell crank lever 63 to rotate shaft 55 against spring bias, whereby pawl (51) rotates shaft 23 through 90 degrees to align the next screw 25 with abutment 39. Each screw 25 carries a gear 110 which may be engaged with a gear on the axially-slidable shaft 64, whereby turning of the latter serves to vary the protuberant length of the screw 25.