JPS5779005A - Controller for shape of rolled sheet material in rolling mill equipped with different diameter work rolls - Google Patents

Abstract

PURPOSE:To rightly control the shape of a rolled sheet material, by prescribing the effective breadth of a backup roll for supporting a large diameter lower work roll to be loaded with a bending force, in a rolling mill equipped with different diameter work rolls in which a small diameter work roll is included in a multistage cluster mill type upper roll group. CONSTITUTION:The said rolling mill is equipped with a small and a large diameter work rolls 1, 4, an intermediate roll 2, backup rolls 3, 5, hydraulic cylinders 6, 6', roll gap adjusting devices 7, 8, and roll housings 9, 9'. When a sheet material S is rolled by this rolling mill, the upside of the sheet material S is supported by plural backup rolls 3 so that the middle convex camber on the upside becomes small, but the middle convex camber on the downside becomes large. The length B in the breadth of the lower backup roll 5 is in effective contact with the lower work roll 4; this length B is made equal to or little smaller than the breadth C of the rolled sheet material S. The breadth C changes with the blank material, however, it is limited in a certain range to be prescribed by the condition of the used rolling mill, so that the length B is set to a value nearly the middle between the maximum and minimum sheet breadths. Hereby, the roll bending effect is hindered, and a cause of generating an edge drop is excluded.