AIR-DRIVEN THREADING DEVICE FOR SEWING MACHINE

摘要

A threading to a looper is performed with one-touch operation. A looper threading/sewing changeover mechanism 30 including a push button 33 for a pressing operation of a push button shaft 32 that a control pin 31 is protruded and provided, a control groove cam 38 which includes a first control groove cam portion 34 - a fourth control groove cam portion 37 which receive the control pin, a connecting movement plate 40 which supports a thread guide portion and which is elastically repelled toward a threading state that a thread guide outlet of the thread guide portion contacts to a looper thread inlet of the looper by a first spring 39, and a connecting positioning plate 82 which rotates together with a main shaft 2 integrally and has a peripheral surface 80 that a tip portion 41 of the push button shaft contacts and has a notch portion 81 that the tip portion of the push button shaft is fitted is provided.