Patent GB-1061703-A (GB)
Title: Improvements relating to double lock stitch sewing machines
IPC: D05B29/06
Filed: 1965-04-22
Abstract: 1,061,703. Sewing g machines. BOND'S WEAR PTY. Ltd. April 22, 1965 [April 24, 1964], No. 17062/65. Heading D1G. A sewing machine adapted to produce 602 or 605 type stitches comprises a presser foot incorporating blades for respectively wiping, holding and cutting the upper threads at the end of a sewing operation, means mounted below the throat plate for slackening and cutting the looper thread, and means for slackening the needle threads. As shown, a sewing machine has three needles provided with respective threads 7 and co-operating with a looper provided with thread 39 and a cover thread laying finger provided with thread 150. A shaft 75 is fast with a pulley 77 adapted to be turned through 270 degrees against the action of a spring 75a, at the start of a sewing operation, by means of a cable 78 actuated by a pneumatic cylinder controlled by treadle means. During the initial part of the rotation of shaft 75, a cam 74 thereon rocks a lever 92 downwards, whereby an arm 157 is rocked for releasing the tension at the needle and looper thread tensioners 40 and the cover thread tensioner 152. Said rocking of lever 92 also serves to raise a rod 62 connected to one end of a lever 60, whereby a rod 65 connected to the other end of lever 60 descends and a first arm rigid with rod 65 engages and draws off the threads 7, while a second arm rigid with rod 65 withdraws a wedge from a thread tensioner to permit the latter to clamp the cover thread 151 adjacent the cutting point. During initial turning of shaft 75, a cam 73 thereon actuates a rod 59 to rock a bell crank lever 55 carrying a fork 57 embracing a pin 14 on a plate (9) Fig. 9 (not shown), slidable in the presser foot 1. During initial movement of plate (9) caused thereby, a wiping blade (10) thereon moves across the needle aperture (5) to carry the upper threads (7) and (151) under a pivoted and spring-biased plate (23), while the continued movement of plate (9) serves to swing a knife blade (17) pivoted to the presser foot under plate (9) across the needle aperture for severing the upper threads thereat, the free ends remaining clamped by plate (23). During initial turning of shaft 75, cam 73 also actuates a rod 54, whereby a rod 46 is shifted axially by a linkage 49 to 53, and a finger 44 on rod 46 presents the looper thread 39 in cutting relationship to a knife blade 30 on a rotary shaft 31. A cam 71 on shaft 75 then actuates a rod 43 to turn shaft 31, via a linkage, for severing the looper thread, the latter also being engaged and drawn off by a finger 38 on a reciprocating rod 36 in said linkage. Final turning of shaft 75 serves to rock lever 92 additionally to effect lifting of the presser foot 1. Lever 92 is connected by a link 115 to one arm of a lever 113, the other arm of which abuts a vertically-slidable pin 109. Depression of lever 92 thereby serves to raise pin 109 for entering a hole 116 in the main shaft 111 only when the needles are raised, to prevent incorrect operation of the thread-cutting devices. In a modification, said devices are actuated by pneumatic cylinders and in said modified arrangement, Fig. 17 (not shown), a cylinder (146) first actuates a finger (150) to pull off looper thread (139), and a bar (142) is then actuated by a cylinder (133) to carry the looper thread forward for severing between a fixed blade (143) and a V-notch (144) in the front face of bar (142).