Patent GB-660476-A (GB)
Title: Improvements in or relating to double lock stitch leather sewing machine
IPC: D05B15/00
Filed: 1949-02-18
Abstract: 660,476. Sewing-machines. WINTERHOFF, W. Feb. 18, 1949 [Feb. 18, 1948], No. 4421/49. Class 112. Lock-stitching by barbed needle and shuttle. An oscillating shuttle 47, Fig. 18, mounted in a fixed race 45 takes the thread loop directly, without the assistance of auxiliary means, from an arcuate needle 78, which has its hook formed in its outer arcuate surface. The shuttle beak 63 projects beyond the cylindrical outer surface of the shuttle body and has behind it a recess 63a to receive the needle as the latter continues to advance to cast off the loop after the shuttle beak has entered it; the shaft of the shuttle driver 77 is eccentric to the shuttle race 45 so that the shuttle is located closely between the driver and the race when entering the thread-loop, as shown, but an appreciable clearance is provided between the driver and the shuttle at the loop-shedding position. In the embodiment described the shuttle is placed below and somewhat to one side of the work support 142, Fig. 1. In one form, the shuttle thread passes out through a hole 52 in the usual bobbin-case 149, Fig. 16, back through a hole 53 and then out through a channel leading between lugs 55 and over a pin 60 lying across the gap between the lugs, the periphery of the bobbin-case being recessed at 56, with a thread-groove connecting the holes 52, 53, to avoid contact between the thread and the interior of the shuttle; the bobbin-receiving spigot in the case 49 is placed eccentrically so that the wall of the case may be made thicker at the recessed part. The bobbin-case is held in place by a bridge member fixed to the lower side of the shuttle race 45 and extending across it, its end being grooved to receive the lugs 55 on the bobbin-case 49 to prevent rotation thereof. In a modification, Fig. 22, the bobbincase is dispensed with, the shuttle body having a recess with a central spigot 179, on which the bobbin is held by a catch; the thread passes through a radial hole into a recess 180 and thence under a leaf spring 183 and out through an axial hole 181. The shuttle-driver shaft is oscillated by teeth engaging a vertical rack 70, Fig. 1 (plan view), which is reciprocated by a cam-actuated.lever 67. The needle, which enters the work from below, is oscillated on a fixed spindle by a similar cam-lever with an arcuate rack on its end actuating a pinion which meshes with teeth on the needle-carrier; this cam-lever is formed in two parts which are relatively angularly adjustable about the pivoting-axis of the lever. A needle-guide, oscillatably mounted on the needle-carrier spindle, is pressed by a spring surrounding its hub towards the point of the needle, its movement in this direction being limited by a pin on the needle-carrier; the guide is pressed back by the work-support when the needle enters the work. The needle-thread passes from the supply 97 through a wax-pot 98, over a tension device 99, through an eye 100 on a cam-actuated thread-controlling lever, through a fixed eye beneath the lever; through another eye 102 on the lever, and down through an oscillating thread-guide 103 to the needle. The guide 103 is oscillated about a pivot 104 by segmental gearing with a member 113 oscillated by a cam-lever 107; it carries the thread round a vertical thread-holder 106 to lay it across the path of the needle, which draws it down off the holder in its descent. The threadholder 106 is longitudinally slidable under spring control; it may be incapable of rotation, or may be made so that it can rotate or be fixed Perforating devices; channelling feed by awl. A curved awl above the work and a channelling knife beneath the work are mounted on carriers adjustably secured together as described in Specification 659,183, and are operated by teeth on the periphery of the awl carrier engaged by similar teeth on the segmented end of a cam lever formed in two parts which are relatively angularly adjustable about the fulcrum of the lever. The awl and channelling-knife carriers are reciprocated along a fixed spindle, to feed the work, by connection to a sliding carriage 131, Fig. 1, actuated by a cam lever 135 which is spring-returned against a stop-screw 138, adjustment of this screw varying the feed by providing for variable initial lost motion. Work supports and guides, outsole-sewing; presser-bars. A shoe is supported sole downwards on a small table 142, Figs. 1 and 18, and is guided by a back-rest formed as a vertical lever adjustable by a set-screw. The work is held by a presser-foot 150, Fig. 1, carried by a spring-pressed presser-bar 151, with locking and releasing means arranged as described in Specification 662,061.