Optimization Procedure and Toolchain for Roll Dynamic Geometry

Abstract

In rolls manufactured from first bent and then welded sheets of steel, the asymmetric distribution of mass due to the weld seam as well as imperfections of the geometry due to the bending may cause the roll cross-section roundness profiles to deform due to centrifugal forces when the roll is accelerated to rotate at its operating speed. This effect is known as the dynamic geometry of the roll. In previous research, it has been shown that it is possible to measure the dynamic geometry in operating speed and compensate for the deformation by grinding a suitable opposite geometry on the roll. This direct approach may work when only little material is removed. Such conditions apply especially for polymer coated rolls, where the dynamic geometry is mostly dependent on the geometry of the much stronger and denser steel body under the roll cover. This paper goes further to investigate the possibilities for compensating the dynamic geometry in cases where the amount of removed material is significant enough to have an effect on the dynamic geometry itself due to altered mass and stiffness. The paper presents a toolchain consisting of a parametric roll CAD model, finite element simulation of the dynamic geometry and a geometry optimization procedure based on minimizing a target function describing roundness errors in cross-sections of the roll. Results of simulation experiments for a case example indicate that the presented optimization procedure can be used to eliminate roundness errors related to dynamic geometry of the roll. Finally, the paper discusses the application of such a toolchain in the manufacturing of rolls.