Watch spring strip - produced from cylindrical wire by cold drawing to final form

摘要

Appropriately heat-treated wire is cold drawn to a rectangular cross-section in such a way that the crystallographic axes are aligned in the longitudinal direction of the strip, and the latter is then further heat-treated to improve its spring properties. The cold-drawing may be carried out in stages with intermediate anneals. Pref. a wire rod is cylindriclly drawn to give 30-60% reduction of area, roll-flattened by 2-8% reduction, and then drawn to final rectangular section with 30-60% reduction.