Rolling theory has made remarkable progress for the last 100 years. The history of rolling theory is described in this report, comparing rolling theory with innovation of strip rolling technology. In Japan, computer control system started to be introduced to iron and steel company in 1960s. Therefore, research of rolling theory became in dispensable. Before 1960, it was published mainly in the Western countries. It is said that two-dimensional rolling theory had been completed. First of all, in Japan flow stress was investigated to calculate rolling load precisely, and approximate three-dimensional analysis for deformation of rolled strip was researched to predict the distribution of rolling pressure in width direction, which made up crown and shape of rolled strip. After that, FEM (finite element analysis method) replaced the approximate three-dimensional analysis, by which three-dimensional deformation of rolled strip could be calculated precisely. The results of these researches supported the innovation of crown and flatness control technology and the invention of many rolling mills with high functional ability for crown and flatness control. Next, the continuous strip rolling theory was completed chiefly in Japan, by which the static and dynamic characteristics of tandem strip mills could be understood. It is said that the continuous rolling technology for cold and hot strip tandem mills would not be realized without the continuous strip rolling theory.

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The numerical analysis model of temperature in a roll and a rolled material was first derived by solving the equations of heat conduction. Next, the occurrence limits of heatstreaks for reduction in thickness and interface temperature in a roll bite were evaluated experimentally and numerically in cold rolling experiments of stainless steel (SUS430) with two kinds of lubricants. Also, the thermal stability of two lubricants was measured by thermal balance experiments. Consequently, the limit of interface temperature due to heatstreaks calculated numerically is almost constant in a lubricant, which suggests that an outbreak of heatstreaks is mostly dependent on the thermal stability of lubricant. Also, larger quantity of synthetic ester is considered to give higher heatstreak resistance in cold rolling of stainless steel.

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