| 摘要 |
PROBLEM TO BE SOLVED: To stabilize the withdrawal amount of a needle thread at the time of a thread end processing and to perform an appropriate thread end processing with less quality decline and needle thread loss even while appropriate stitch balancing thread tension is maintained at all times and prescribed zigzag stitches are surely formed regardless of the change of the thickness of a sewing cloth or the like at the time of normal sewing. SOLUTION: In athe zigzag stitch sewing machine provided with a wiper for picking a needle thread end part suspended from a needle and moving it to the side after sewing and a needle thread cutting knife for cutting the needle thread end part near the upper surface of the sewing cloth, in the route of supplying the needle thread to the needle 8, a rotary disk type needle thread tension device 14, a pretension mechanism 15 for imparting tension to the delivery of the needle thread 13 beforehand and an auxiliary needle thread holding mechanism 16 capable of elastically holding the needle thread 13 on the upper side in a needle thread supply direction from the pretension mechanism 15 are provided. Also, an operation switching mechanism 26 for selectively switching the pretension mechanism 15 and the auxiliary needle thread holding mechanism 16 to an operation state is provided. COPYRIGHT: (C)2005,JPO&NCIPI
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