Approach to evaluate the rolling mill capacity in a plate rolling process

Abstract

This study presents an approach to evaluating the rolling mill capacity from the viewpoints of productivity and revamping cost when a plate mill is upgraded. In this light, a concept is proposed of a ‘characteristic length’, defined as the ratio of the design torque of the drive motor over the design force of the rolling equipment (structure of the rolling mill). A draft schedule algorithm for the plate rolling process is also presented, which consists of a force–thickness relation at each pass, and a roll force and torque prediction model. Using the draft schedule algorithm linked with the characteristic length, a series of plate rolling analyses was performed to examine the productivity of a plate mill while varying: (i) the design force of the rolling equipment; (ii) the design torque of the drive motor; (iii) both its design force and torque; and (iv) the strength of the slab. In addition, as a practical example, the proposed approach has been applied to three actual plate mills in Korea, China, and Russia. The results reveal that upgrading the design torque is the most efficient method from the viewpoint of productivity and revamping cost. It was also found that a critical characteristic length exists in which productivity cannot be increased any further, even though the rolling mill capacity has been upgraded further. Hence, this critical characteristic length can be used as an index to avoid the overcapacity problem of a plate mill when it is revamped.