| 摘要 |
In a looper and cutter drive mechanism for sewing machine, an upper looper and a lower looper are respectively disposed below a throat plate, respective loop-taker points of these loopers are arranged in the same direction such that the loop-taker points pass a front side of the needle as seen in the stitching direction. The upper looper and the lower looper are driven such that the upper looper and the lower looper perform movements having traces on planes substantially parallel to each other. Due to such a constitution, the looper drive mechanism has both of the lockstitching function and the over-edge stitching function and can perform both functions by a single sewing machine. Further, the rotational movement of an upper shaft of the sewing machine is transferred to the upward and downward movement by way of a motion transfer mechanism which is operated in an interlocking manner with the rotational movement and a fabric edge is cut by an upper cutter which is operated corresponding to the upward and downward movement and a lower cutter which is cooperatively operated with the upper cutter. Here, the upper cutter is slidably guided by a cutter drive portion which is pivotally mounted on a frame. The motion transfer mechanism is connected to the upper cutter by way of a clutch. The clutch transfers power to the upper cutter at the time of performing the cutters of the cutter drive portion and pivotally moves the cutter drive portion to a shunting position and interrupts the transmission of power to the upper cutter at the time of not performing the cutters.
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