Modernization of Hot-Rolled Tubes Rolling Method

Abstract

A new method of hot-rolled pipes rolling on the automatic tandem mill is suggested. It consists of two rolling stands. This method allows achieving the rough pipe preovalisation before reaching the automatic mill. The rough pipe preovalisation provides even groove filling and the decrease of pipe wall thickness variation. The rough pipe preovalisation will allow increasing the elongation ratio from 1.5 to 2.0 on the lengthwise rolling stand no. 1 and decreasing the elongation ratio on the piercing mill, therefore the chance of rolling skin formation on the external surface of the pipe is decreased. The way to reduce the probability of the formation of a guide mark defect due to the kinematic tension during rolling on a stub mandrel with rough tube preovalisation is investigated. The influence of the kinematic tension factor on the pipe forming in the groove taper at a lengthwise rolling with rough tube preovalisation is explored.