| 摘要 |
PURPOSE: To surely cut or hold a lower thread by freely and easily changing a waiting position or closing quantity in a lower thread cutter for a sewing machine for buttonholing. CONSTITUTION: In the lower thread cutter 130 provided in the sewing machine for buttonholing for cutting the lower thread after the formation of buttonholing, the cutter is provided with lower thread cutting scissors 52 for cutting the lower thread and holding the cut lower thread at the prescribed waiting position while looping it, a pulse motor 131, and a driving cam member 134 to be driven for opening/closing the lower thread cutting scissors by being driven and rotated by the pulse motor 131. By changing the rotating position of the driving cam member 134 in the case of stopping rotation from an original position in a direction (n), the waiting position can be changed, and by changing a rotating position where the driving cam member 134 arrives when rotating in the direction (n), the closing quantity of the lower thread cutting scissors 52 can be changed. By changing a rotating position where the driving cam member 134 arrives when rotating in a direction (m), the opening quantity of the lower thread cutting scissors 52 can be changed.
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