Patent ID: 10767293

Abstract:
A sewing-thread pre-stress device for a sewing machine includes: a sewing-thread support, a pre-stress supply member, an abutting member and a top cover. The sewing-thread support includes an accommodating groove with a groove bottom. The pre-stress supply member is made of elastic material, provided in the accommodating groove, and has a folding portion which has two extension portions with one end connected to two sides of the folding portion. The abutting member is disposed on the pre-stress supply member, and the two abutting portions abut against the abutting member. The top cover is disposed on the abutting member and fixed to the sewing-thread support to define a thread space between the top cover and the abutting member for allowing a sewing thread to be inserted therethrough. The member is elastic and V-shaped, therefore the elastic force change is relatively small, which can provide the sewing thread an appropriate tension.