GB1121608A - Improvements in or relating to chain stitching on sewing machines - Google Patents

Abstract

1,121,608. Sewing machines. JANOME SEWING MACHINE CO. Ltd. 8 June, 1967 [9 June, 1966; 11 July, 1966], No. 26599/67. Heading D1G. A lock stitch sewing machine is converted to chain stitching by providing a loop retainer which rotates co-axially with the rotary lock stitch looptaker, the arrangement being such that the thread loop expanded by the looptaker is held in expanded condition by the loop retainer, the needle in its next descent passes through the expanded loop to form a fresh loop, and the expanded loop is shed from the retainer to engage the fresh loop for forming a chain stitch. The rotary looptaker 1, having a loop-seizing beak 4, journals a bobbin carrier having a central pin 7. The loop-retainer 6 has a hub 16 bored to receive pin 7 and secured thereto by a grub screw 23. Rigid with hub 16 is a diametrically-disposed web 17, from the opposite ends of which extend helicallyshaped fingers 9 and 10 respectively. Finger 10 ends with an axially-disposed thread-engaging edge 18. Finger 9 and edge 18 extend within the outer end surface of looptaker 4. Thread-retaining notches 19 are formed at the ends of web 17 at the junctions of fingers 9 and 10 therewith. Boss 16 is secured to looptaker 1 by a tongue and groove connection (not shown), with web 17 disposed substantially at right angles to the diametrical line through beak 4 and with finger 10 disposed on the side of web 17 away from beak 4. In operation, an initial thread loop Ro, seized by beak 4 from the needle 2 and expanded over the looptaker body, is guided by the fingers 9, 10, after the loop has been cast off by beak 4, into engagement with the notches 19. The needle on its next descent to seize a fresh loop Rn, passes into the expanded loop Ro, and the latter, on further rotation of the looptaker, is shed from the loop-retainer 6 and is tightened by the take-up 57 upon loop Rn. Expansion of a loop by the loop-retainer 6 serves to draw thread from and thereby tighten the previously formed stitch. A thread-guiding pin 59 is positioned adjacent take-up 57 to restrict the supply of thread thereto, and the thread tension, as set by the tensioner 56, is increased over that required for lock stitching. The looptaker and thread-retainer may form an integral unit.