Under thread supply apparatus and method of supplying under thread

摘要

An under thread supply apparatus for a sewing machine comprises a bobbin case, a bobbin exchange device, a thread removal device and a winding device. The bobbin case is removably set to a shuttle of the sewing machine and accommodates a bobbin with the thread wound thereon. The bobbin exchange device takes the bobbin case out of the shuttle, and set the bobbin case accommodating the bobbin with the thread wound anew therearound to the shuttle. The thread removal device removes the thread from the bobbin accommodated in the bobbin case which is taken out. The winding device winds a preset amount of thread around the bobbin after the thread is removed therefrom.