GB724992A - Improvements in sewing machines - Google Patents

Abstract

724,992. Sewing-machines. UNION SPECIAL MACHINE CO. Jan. 16, 1953 [Jan. 18, 1952], No. 1324/53. Class 112. Feed; lock-stitching by rotary hook; multiple-needle machines. In needle-feed lock-stitch machine with a vertical-axis rotary hook and the usual feed-dog co-operating with the needle, the underside of the feed-dog is provided with guard means to keep the needle-thread loop, as it is being drawn out by the hook, from catching over the upper surface of the feed-dog. The invention is particularly applicable to a twoneedle machine in which both hooks 28, 30 (Fig. 2) rotate in the same direction (clockwise as shown), so that one of the hooks (30) draws its needle-loop out rearwardly, and this loop is liable to balloon out and catch over the corner of the feed-dog 24, the thread then being broken by the action of the take-up. In the form shown in Figs. 5 and 7 the feed dog has a divided upper portion with the main feeding surfaces formed on outward flanges 88, 90, and the guard in question is constituted by a rib 110 formed at the rear of the under surface of the flange 90 (adjacent to the hook 30 which takes its loop in a rearward direction). A similar rib may be formed at the front of the other flange 88 to confine the other needle-loop which is thrown forwards by the hook 28. The hooks are driven by spiral gears 52 from a shaft extending along the machine bed, and the thread cases 66 are prevented from rotating by projections 67 engaging notches in the underside of the throat-plate; the bobbins 68 are retained by spring arms 68a. Hook opener means are provided to shift the thread cases in a counterclockwise direction at the appropriate time in each stitch-forming cycle to facilitate movement of the needle threads part the projections 67; these means comprise fingers 70 mounted on rock-shafts 74 and engaging with projections 76 on the threadcases. The bobbin threads are tensioned by screwadjusted spring members 71 beneath which the threads pass and which have fingers 71a that may bear frictionally on the bobbins. The feed-dog has a downwardly-extending portion 98 which is secured to a vertical part of a feed-bar 100 attached to a downwardly-extending lift-eccentric strap 102 and to a feed-rocker 106. The body of the feed-dog is recessed on each side at 118 to clear the needles and threads. Needle-guides. A member 116, Fig. 5, of trapezoidal form with its sides inclined upwardly and inwardly, projects between the needles from a channel-shaped attachment portion 112, which fits over and is fixed to the shank of the feed-dog 24. Lubricating. Each hook-shaft has a helical groove to raise oil which is fed to its lower end from a reservoir through a filter and a regulating valve; Specification 564,468 and U.S.A. Specification 2,329,484 are referred to.