Development of New Type of Cluster Mill for Plate Flatness Control

摘要

The new type of cluster mill (Nippon Steel Intelligent Mill: NIM) is developed, which enables to control plate flatness with high accuracy. Conventional and widely used way for flatness control for plate rolling is to detect plate flatness after rolling by using flatness measurements. Of this kind of system, though, sensors are usually located several metres away from rolling mill, and consequently, this situation may cause an inevitable control delay. In contrast, the basic concept of NIM is real-time control of plate flatness i.e. force distribution control between work roll and material while rolling, enabled by load detection of each divided backup roll and prediction of force distribution through work roll by bending calculation. According to this new concept, the authors have invented a prototype mill with specification of; top cluster type backup rolls which directly contacting work roll with zigzag alignment in plan view, top work roll, bottom work roll, and bottom backup roll (not cluster type). This prototype mill reveals that it has great flatness control capacity despite any entry materials' flatness and particularly notable that the above concept is valid for even such very small reduction rolling as from 0.1 to 0.2 percent for more than 5 percent entry materials' steepness.