Thread chain, as well as a method and device for tensioning of the thread chain in more compartment needle sewing machines

摘要

PURPOSE: To smoothly draw out a stable open ring in the sewing machine having two needles and one looper. ;CONSTITUTION: An auxiliary blade 21 is provided in parallel in a looper 4, thereby an open ring connected to the looper 4 is supported so as not to be caught by the looper 4 by preventing the hanging-down caused by pushing the open ring into the lower part of a needle plate 3. In a pinhole of the needle plate 3, the tip of a slender plate 19 is protruded so as to be movable forward and backward, and performs a function as a claw. The sewing machine is provided with a thread tension utensil group for sewing and a thread tension utensil group for forming the open ring, it is switched to the thread tension utensil group for forming the open ring at the time of forming the open ring, and tension of one needle thread is maintained in the same way as the time of sewing, and on the other hand, tension of the other needle thread and tension of a looper thread are respectively made small and large. At the backward in the cloth feeding direction of the needle hole 13, a backward feeding tooth 16 for feeding out the open ring is provided, and a guide groove is formed toward the center of the backward feeding tooth 16 from the left side of the needle hole 13.;COPYRIGHT: (C)1993,JPO&Japio