The term "fine steel" refers to very thin (25 μm to about 0.2 mm) steel strip used to make integrated circuit lead frames, shadow masks, and other such electronic parts. And, as one would expect, shape and surface quality requirementsfor this material are extremely stringent. In conventional practice, fine steels are rolled on cluster mills or the like. However, with increasingly strict demands for surface quality, there has been a growing concern about support marks imprinting onto the strip from the segmented support rolls found on such mills. Here, directing our attention toward the design of a rolling mill that does not have segmented support rolls within the range of the strip width, we developed the Universal Crown Control Mill for fine steel (UC1F-MILL) for the cold rolling of fine steel and other ultra-thin materials. The UC1F-MILL provides a high degree of surface quality by the use of support rolls mounted outside of the range of maximum strip width and which act to horizontally support the work rolls from both the entry and delivery. Furthermore, the newly developed mill allows for the stable control of shape by (a) varying the offset of the work rolls and (b) applying a horizontal bending force to the work rolls to minimize work-roll horizontal deflection. The UC1F-MILL has been installed and recently put into service at two plants in Japan.
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