GB190823025A - Improvements in or relating to Lock Stitch Sewing Machines. - Google Patents

Abstract

23,025. Plant, T. G. April 15, [date applied for under Section 91 of Patents &c. Act, 1907]. Boot-sole stitching-machines; lock-stitch shuttle sewing-machines ; governing needle thread.-To secure a uniform location of the interlock between the needle and shuttle threads, with respect to the surface of the work, means are provided whereby the stitch-setting pull on the needle-thread is exerted on a taut shuttle thread and such pull draws from the shuttle the full amount of thread necessary for the stitch, thus preventing the threadlock from being disturbed on the return movement of the shuttle. The needle-thread is governed by a tension device t', a thread clamp h, a main take-up arm g<5>, carrying the roll 9, mounted on the stud g<6> and operated from the shaft A', and an auxiliary take-up g<4>, having a spring 8, a roll 5, and a stop 34 engaging the thread-measurer g. The shuttle 10, which is driven from a cam-operated rack D<1>, has the usual nose 11 and carries an eccentrically mounted bobbin-case 13 provided with a delivery eye 14 and guided by a recess in the under face of the arm D<6>, To form the stitch the shuttle 10 is oscillated from the position shown in Fig. 5 to that shown in Fig. 3 to engage and cast the needleloop and then back to its original position, the vertical rise of the bobbin centre 21 and consequently of the eye 14 being greater in the forward than in the return movement, such movements being given by imparting to the shuttle an oscillating movement in the arc of a circle to substantially the same extent on either side of a line connecting the stitch-making point to the centre of oscillation 20 of the shuttle. Consequently the shuttle in its forward movement carries the delivery eye 14 to a position at least as far from the stitchmaking point as it does on its return, and the lock is thus formed with the shuttle thread a taut, and the needle-thread, when manipulated by the takeup to set the stitch, pulls from the shuttle all the thread required, and the lock is not disturbed by the return movement.