Stabilizing the transverse profile and hardness of S1 alloy strips during rolling, taking into account the asymmetric stiffness of the roll assembly

This study present the results of test rolling of narrow strips made of S1 lead alloy on a 130 × 10 two-high mill, along with methods for improving the quality of rolled products. The dimensional changes of strips with an initial thickness of 2 mm and a width of 10 mm were investigated during six-pass rolling to a final thickness of 0.9 mm. After rolling, the transverse wedge of the strip edges was found to range from 0.02 to 0.03 mm, exceeding the allowable limits. It was demonstrated that as the draft increases from 30 to 50–55% from pass to pass, the transverse thickness variation decreases from 0.05 to 0.02 mm. Linear regression equations were derived to predict the effect of the number of passes on the transverse profile and the wedge angle. Measurements revealed that the upper side of the top roll, which is not fixed in the housing, is elastically deformed by about 0.03 mm, resulting in uneven pressure distribution over about 4 mm along the roll body. This uneven pressure causes nonuniform transverse deformation of the strip during rolling. The study also examined the effect of uneven transverse deformation on strip hardness, revealing a hardness variation from 50 to 58 HV across the width. Linear regression equations were derived to predict the relationship between strip hardness and thickness for a rolled S1 alloy strip. Based on the findings, a rational profile for the top roll was proposed to eliminate the irregularities of transverse deformation. The improved technology and equipment enable the production of high-quality S1 alloy strips on the two-high mill of the Bogorodsky Branch of the NPO Pribor machine-building company.