THREE ROLL ELONGATOR AND MANUFACTURE OF CLAD STEEL TUBE WITH THREE ROLL ELONGATOR

摘要

PURPOSE:To manufacture the above clad steel tube without generating peeling and crack by giving a negative convergence angle to each roll of a three roll elongator and providing guide shoes freely movably forwards and backwards between every rolls. CONSTITUTION:A tubing is rolled by inserting a mandrel 3 (or plug) into a metallic tubing 2' with skew rolling method in the three roll elongator and of which each roll 1 is given with a negative convergence angle. Between a pair of adjacent rolls 1, the guide shoe 7 with which bulge between every rolls 1 with rolling the metallic tubing 2' is prevented are provided. Those guide shoes 7 are made to be movable freely forwards and backwards from a roll stand 4 which supports each roll 1 toward the axial line of the metallic tubing 2'. In this way, the angle of torsion is reduced and the generation of flaring can be restrained.