Headrest lock structure with lock slots, method for forming lock slots in headrest pole and method for producing headrest pole

摘要

A headrest lock structure has a plurality of lock slots formed in a line along the axial direction of a cross-sectionally circular headrest pole and a lock plate is adapted to fit into one of the lock slots. Each lock slot has a bottom surface protruding in an arc within a region concaved from the outer peripheral surface of the headrest pole by a given distance, and a side surface formed on at least one of the sides of the bottom surface in the axial direction of the headrest pole to extend at approximately a right angle with the bottom surface. The lock plate has an arc-shaped concave portion corresponding to the profile of the bottom surface of each lock slot, and a flat portion corresponding to the side surface of each lock slot. The headrest lock structure can reliably prevent unintentional release of headrest lock.