Patent GB-875326-A (GB)
Title: Cyclic sewing machine
IPC: D05B23/00
Filed: 1958-04-24
Abstract: 875,326. Sewing machines. SINGER MANUFACTURING CO. April 24, 1958 [May 22, 1957], No. 13025/58. Class 112 Frames. In a group stitch sewing machine the frame comprises a work-supporting arm 11 and an upper arm 13 both of which project from a standard 12, and the latter is supported by a separate base 27 provided with feet 28. A rotary cam disc 36 is fixed to a gear 32 which is journalled on a flanged spindle 29 depending from the base 27. A screw 30 serves to connect the spindle, base and standard together, and a pin 31 serves to prevent relative angular movement of these parts. Gear 32 is driven by a vertical shaft 43 from the main shaft 14 of the machine. Feed by clamps. The lower jaw 106 is fixed to a flat plate 107 extending within the standard 12. The upper jaw 108 is fixed to a bar vertically slidable in an arched bracket 109 fixed to plate 107. A spring 110 biases jaw 108 downwardly. A slide block 117 rigidly fixed to plate 107 is confined in a slot formed in a guide block 118 pivoted to a lever arm 119 fixed to a fulcrum pin 120. A lever arm 121, also fixed to pin 120 is connected via a link 122, lever 123, adjustable pivot pin 126 and lever 124 to a vertical rock shaft 125. A follower 128 on the latter is disposed in a cam groove 38 formed in the upper surface of disc 36, rotation of which thereby imparts movement to the clamp transversely of arm 11. A second upper cam groove 37 is tracked by a follower 129 on a vertical rock shaft 131 connected by levers 132, 133 to plate 107, whereby rotation of disc 36 imparts movement to the clamp lengthwise of arm 11. Presser bars, lifting. A lever 66, pivoted at 50, is connected by a link 116 and arm 115 to a rock shaft 114 which is operatively connected to a vertically slidable bar 111. A finger 112 on the latter underlies a pin 113 on the bar carrying jaw 108, whereby operation of lever 66 serves to raise the latter. Starting and stopping. A two-part driving pulley has an element 47 fixed to shaft 14 and an element 48 rotatable and slidable thereon. A frame 52, pivoted at 50, is connected to a stop lever 53 journalled and slidable on shaft 14. A rod 55, slidably mounted on frame 52, is centred by opposed springs 56 and is pivoted to the stop lever 53. A spring 64 normally biases frame 52 clockwise to the position shown, when an arm 54, fixed to frame 52, is spaced from a thrust bearing 49 on element 48, and stop lever 53 is engaged in a stop-notch in element 47. A lever 60, pivoted at 50, is connected by a link 59 to a pivoted latch-block 58, and the latter is connected by a link 57 to frame 52. Operation of lever 60 thereby swings frame 52 counter-clockwise to disengage lever 53 from element 47 and to engage arm 54 with element 48 for transmitting drive to shaft 14. A latch finger 61 is biased by a spring 62 to engage the second one of a pair of notches 63 in block 58 for holding frame 52 in the driving position. A pair of cam lugs 41 adjustably fixable in an arcuate slot 40 in the bottom of disc 36 are adapted successively to co-operate with a follower 70 for rocking a vertical shaft 73 journalled in a hollow shaft 74, and an arm on the upper end of shaft 73 is connected by a link 82 to finger 61. The arrangement is such that when the first lug 41 engages the follower 70, shaft 73 rocks sufficiently to transfer finger 61 from the first to the second notch 63, whereby arm 54 moves away from element 48. Shaft 14 then coasts until the second lug 41 engages the follower 70, when finger 61 frees block 58 and arm 53 is thereby carried into the notch in element 47 to stop shaft 14, the momentum being absorbed by the springs 56. Thread cutters. Fingers 85, 86, are fixed to a gear 89 which is pivoted on a pin 88 under the throat plate 87 and meshes with a rock 90 on a slide bar 91 which is also connected to an arm 77 on the upper end of shaft 74. An arm 95 on the lower end of shaft 74 is connected by a link 94 to a lever 93, and the latter carries a follower 92 disposed in a cam groove 39 formed in the lower surface of disc 36. The clamp-opening lever 66 is connected by a link 101 to a lever 99 which is in turn connected to the slide bar 91. The arrangement is such that as the needle begins to descend for the last stitch, finger 85 is moved to engage the bobbin thread, and immediately the needle thereafter ascends from the work, finger 86 is moved to engage the needle thread loop. When lever 66 is subsequently operated to open the clamp, a knife edge in finger 85 co-operates with a groove 104 in the throat plate 87 to sever the bobbin thread, and a knife edge 102 on finger 86 co-operates with a ledger blade 103 to server the needle thread. Specification 751,938 is referred to.