Tribological properties of cemented carbide rolls in cold sheet rolling

摘要

When high elastic modulus rolls are applied to cold rolling, roll flattening becomes smaller than with conventional steel rolls. This factor reduces the rolling load by decreasing the contact length between the roll and the sheet being rolled. Conversely, the smaller roll flattening radius increases the contact angle between the roll and the sheet, which reduces the thickness of the lubricating oil film carried into the roll bite. This factor increases the rolling load by increasing the friction coefficient in the contact area. The influence of the roll material on rolling load appears as the sum of these two factors. However, few studies have attempted to separate and evaluate their effects. To clarify the effect of the roll material on rolling load, a series of experimental cold sheet rolling tests was conducted with cemented carbide rolls and conventional steel rolls. The experimental results showed that the difference of the rolling load between cemented carbide rolls and conventional steel rolls varied with rolling conditions. To investigate the lubricant behavior in rolling, a numerical analysis of the oil film thickness was carried out. Based on the experimental results and the calculated oil film thickness, the effect of the roll material on rolling load was discussed.