GB1007918A - Chain stitch device for lock stitch sewing machines - Google Patents

Abstract

1,007,918. Sewing machines. SINGER CO. Aug. 4, 1964 [Aug. 7, 1963], No. 31662/64. Heading D1G. A lock stitch sewing machine, modified to produce chain stitching, comprises a work support formed with a needle aperture, a rotary looptaker disposed beneath said support, a bobbin-supporting case journalled in the looptaker and constrained from rotary movement therewith, a stationary thread loop engaging finger disposed beneath said work support in advance of the needle aperture and parallel to the path of needle reciprocation, threaddirecting means carried on the bobbin case and cooperating with said finger for directing thread manipulated by the looptaker on to the finger, and a reciprocating element disposed between the needle aperture and the finger for stripping the thread loops from the latter when the needle penetrates the needle aperture. A conventional lock stitch sewing machine comprises a vertical axis rotary hook 32 formed with a loop-seizing beak 33 and journalling a bobbin case 34 constrained from rotation by a leaf spring engaging an abutment 37 thereon, is modified by the provision of a thread loop engaging finger 70 carried by a fixed leaf spring 71 which biases finger 70 against an abutment projection 77 on the bobbin case. The descending needle 19 carries a thread loop through a loop A<SP>1</SP> held on finger 70, when a web 80 on the descending feed dog 50 strips loop A<SP>1</SP> from finger 70. The fresh loop, when shed by the looptaker, rests on projection 77 until tightened by the take-up to engage finger 70. The bobbin thread B is concatenated with the needle thread loops, but lies on the undersurface of the work and may be readily withdrawn from the seam. The needle aperture is elongated in the direction of work feed.