The device used to lift the upper roll and prevent the impact of the rolling stock from entering and leaving the roll. The forms are: spring type, mostly used in profile rolling mills; heavy hammer type, commonly used in the large rolling mills with large amount of movement; hydraulic type, mostly used in four-roll plate strip rolling mills.
In order to increase the operating rate, it is required that the roll change roll be quick and convenient. There are four types of roll changer: C-shaped hook, sleeve type, trolley type and full rack change roll type. In the first two ways, the roll changer is used to assist the operation, while the whole rack change roll needs two sets of stands. This method is mostly used for small rolling mills. The trolley change roll is suitable for large rolling mills and is conducive to automation. At present, rapid automatic roll change devices are used on rolling mills, and changing the rolls only takes 5 to 8 minutes.