LARGE STRAIN INTRODUCING WORKING METHOD AND CALIBER ROLLING DEVICE

摘要

A method of rolling with a flat-shaped hole die in a 1st pass and subsequently rolling with a square-shaped hole die in a 2nd pass in a hole die rolling of two or more continuous passes. The rolling is performed with a caliber which sets the ratio of the minor axis (2A01) of a 1st pass flat to a material opposite side dimension (2A0) to A01/A0 <= 0.75 and the ratio of a 2nd pass vertical diagonal dimension 2As1 to the major axis 2B1 of a material after the 1st pass to As1 /B1 <= 0.75 to introduce the large strain into the material. Thus, the effect of the distribution of strain introduced into the material in the 1st pass on the distribution of strain and the shape of the next pass is made clear so that the large strain can be introduced into the entire cross sectional area of the material, particularly at the center of the material.