GB1002567A - Improvements in or relating to sewing machines suitable for use in the manufacture ofshoes - Google Patents

Abstract

1,002,567. Sewing machines. BRITISH UNITED SHOE MACHINERY CO. Ltd. June 7, 1962 [June 14,1961], No. 22012/62. Heading D1G. A shoe inseam sewing machine has a curved hooked needle 4 mounted for oscillation about a horizontal shaft 22, a needle, threading looper 6, a channel guide 14 for an insole rib, and a take up 10 adapted to tighten the thread loop surrounding the needle while the latter is in the work, and to give up thread 15 to the looper, while the latter is laying thread in the needle hook, faster than required by the looper. The needle is carried by a segment 24 journalled for oscillation on shaft 22 and arranged for reciprocation axially on the latter in the line of feed with a bracket 62 which carries both the channel guide 14 and also an oscillating thread finger 8. An awl 5 is carried by an oscillating segment 30 also arranged for reciprocation in the line of feed. The needle and awl thereby act alternately to effect continuous feeding of the work. The thread finger comprises a cranked arm 58 which extends forwardly above and downwardly in front of the needle shaft 22. The upper end of arm 58 is detachably fastened to a rock shaft 60 journalled in bracket 62 on an axis parallel to and in advance of the plane containing the needle curvature. The tubular looper 6 is clamped for axial adjustment in a block 76 pivoted, for angular adjustment, in a block 80 which is attached to a bar 86 by a tongue and groove connection 82 for adjustment in the line of feed. The take up 10 is carried at one end of a lever, the other end of which carries a follower roller 38 engaging a cam slot 40 formed in a cam disc 42 fixed to a rotary shaft 46. In the rest or O degrees position of the cam disc 42 the needle is retracted from the work and the thread finger is in a position farthest to the left and in advance of the plane of needle curvature. During the first 75 degrees of rotation of disc 42 cam slot 40 approaches shaft 46, whereby the take up tensions the thread to set the previous stitch. The thread finger in its rightward movement then engages the thread and the looper commences to encircle the advanced needle. It is stated that in previous machines the cam slot 40 thereafter had a continuously increasing radius of curvature, as shown in dotted lines 48, to impart a steady thread giving up movement to the take up at a rate slightly less than required by the looper and thread finger for laying the thread in the needle hook, whereby deflection of the needle and possible fraying of the thread resulted. In the present arrangement cam slot 40 has a rapidly increasing radius between 75 and 131 degrees, whereby the take up gives up thread faster than required by the looper and thread finger to provide slack thread during the looping operation, Fig. 6. Between 150 and 170 degrees the cam slot is designed to apply slight tension for drawing the thread into the needle hook. The needle then commences to retract and the thread finger moves leftwards to give up thread to the needle. The cam slot has a dwell between 222 and 360 degrees, the needle being fully retracted at 255 degrees. It is stated that release of thread tension during the looping operation, in addition to preventing needle and thread damage, aslo ensures reliable tightening of the first stitch inserted into the welt by preventing the thread end 49 being prematurely withdrawn from the thread end holder jaws 50; additionally enables the thread finger to be made less robustly in its present form in contract to its previous arrangement as an arm extending under the needle shaft 22 radially from a rock shaft, thereby to provide more space for the untrimmed margins of the shoe upper; and also enables the thread finger "in some instances" to be eliminated entirely. Specifications 369,264, 629,758, 723,595, 811,605, 900,976 and 941,316 are referred to.