MANUFACTURE OF JOINT FOR SCREWED REINFORCING BAR AND COLD ROLLING DEVICE

摘要

PROBLEM TO BE SOLVED: To manufacture a joint for screwed reinforcing bar at low cost. SOLUTION: In a cold rolling device provided with a feeder 11 which loosely inserts a mandrel C having a male screw corresponding to the female screw of a screwed reinforcing bar on the outer peripheral face into a tubular stock W and which further pushes the mandrel C and the tubular stock W simultaneously into a plurality of grooved pendulum rolls 7 and a drawing hole 13 which is formed by the grooved pendulum rolls 7, the tubular stock W inserted into the mandrel C is subjected to cold rolling, the outer shape of the tubular stock W is drawn to a prescribed joint shape, and at the same time the female screw to screw-engage with a screwed reinforcing bar is formed to its inner peripheral face.