Thread cutting device for sewing machine

摘要

The invention relates to a thread cutting device (20) for a sewing machine (10). The thread cutting device (20) includes an upper knife (22), a lower knife (23), an open-close link (24) coupled to the upper knife (22) and the lower knife (23), a drive source (28) coupled to the open-close link (24) to move the open-close link (24) back and forth along a linear direction. A thread is cut by closing the upper knife (22) and the lower knife (23). The thread cutting device (20) further includes a conversion link (25) having one end rotatably coupled to the open-close link (24) and the other end rotatably coupled to the lower knife (23). The conversion link (25) converts the back-and-forth movement of the open-close link (24) into a circular movement and transmits the circular movement to the lower knife (23).