Lead screw for moving a head

摘要

A lead screw for moving, for example, a printing head or a magnetic head. The screw is molded from plastics by a split mold comprising a plurality of longitudinally extending sections. It has on its outer peripheral surface a helical groove satisfying the following relationship: where P: pitch of the groove; R: radius of the screw; r: radius of the screw between its longitudinal axis and the bottom of the groove; theta : angle of division of the mold sections; and L: a half of the difference in width between the top and bottom of the groove. The bottom of the groove is smaller in width than the top thereof.