MANUFACTURE OF BACKING STRIP WITH PROJECTION FOR WELDING SQUARE PIPE AND ITS DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a method and device for manufacturing a backing strip with projections for welding a square pipe capable of shortening a working time, executing mass production and also coping with them by the use of the same steel regardless of the size of the backing strip. SOLUTION: A long size of steel plate is rolled and a projected line 7 continuous in the longitudinal direction is formed on the steel plate by means of a roughing mill consisting of an upper roughing roll 3 wherein a groove continuous in the circumferential direction is formed on the surface and a lower rolling roll 4 having a plane shape of surface which is provided facing the upper roughing roll 3. Thereafter, the steel plate wherein the projected line continuous in the longitudinal direction is formed is rolled and the projections at a prescribed pitch are formed by means of a finishing mill consisting of an upper finishing roll wherein plural projection forming recessed parts are formed in the position corresponding to the projected line 7 on the surface at a prescribed pitch in the circumferential direction and a lower finishing roll having a plane shape of surface which is provided facing the upper finishing roll. The steel plate wherein the projections at the prescribed pitch are formed is shaped into the backing strip with the projections for welding the square pipe.