Thread cutting knife device in a sewing machine

摘要

A thread cutting knife device in a sewing machine having a bed has a lower shaft rotatably supported at the bed and a throat plate mounted thereon. A hook is attached to the lower shaft and extends beyond a throat plate. A thread cutting knife and a loop spreading plate are adapted to cross between the hook and the throat plate to cut a needle thread looping portion at a cloth side and a bobbin thread. The knife and the plate are respectively rotatably supported by the lower shaft. The knife has a blade at an upper edge of the tip end thereof. The loop spreading plate has a thread dividing portion extending into the needle thread looping portion at the cloth side and a thread looping portion at the side of the needle. A thread drawing portion is formed at one edge of a base of the dividing portion for holding the needle thread looping portion at the cloth side and the bobbin thread. A blade positioned at the side of the throat plate and is opposed to and crosses the blade of the thread cutting knife.