| 摘要 |
Process for controlling the over-thread of a sewing machine, which has a needle holding the over-thread and vertically movable in association with an arm shaft, a gripper holding a bobbin case for an under-thread and rotatable in association with the arm shaft and intended for forming a lockstitch in cooperation with the needle, and a yarn holder vertically movable in association with the arm shaft and intended for loosening or picking up the over-thread, in which process a tension necessary for stitch fixing is applied to the over-thread for a period of time from a moment when an over-thread loop is loosened by the gripper to a moment when the stitch fixing is concluded, whilst, for a period of time from the moment before the over-thread loop runs through an interspace between a recess and a tab of a rotary restraining finger to a moment after the release of the over-thread loop by a loop-control tip of the gripper, a restraining force is applied to the over-thread, in order to prevent the over-thread from being dispensed from an over-thread supply source.
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