ANALYSIS OF ROLLING PRESSURE IN WALL-THICKNESS REDUCTION ZONE OF SIZING-ROLL AND OF MANDREL AXIAL FORCE WITH RESPECT TO DOUBLE-COIL-WELDED TUBES（Ⅱ）

The calculation formulas are derived with analytical method for rolling pressure, total rolling force and mandrel axial force in wall thinning zone of sizing rolls and a conic-cylindrical mandrel. The calculation result is compared with that relate to the crowned mandrel, which results in the diseovety of the advantages of the conic-cylindrical mandrel and the measures proposed to steadly apply conic-cylindrical mandrel.