A flexible electromagnetic control technique for interference adjustment in large-size sleeved backup rolls

Abstract

Large-size sleeved backup rolls including the roll core and roll shell play a crucial role of supporting work rolls in the precision-rolling process. However, since the backup roll endures an unavoidable periodic force during the rolling process, the interference between its roll shell and roll core is correspondingly reduced, which leads to rolled strip defects or a decreased service life of the roll. To solve this problem, an interference electromagnetic control technique (IECT) was proposed for large-size sleeved backup rolls to freely regulate contact pressure between the roll core and roll shell using a thermally driven electromagnetic stick mounted inside the roll core, thereby adjusting the interference for large-size sleeved backup rolls. In this study, a finite element method (FEM) simulation of a ϕ1400 × 1420 mm size sleeved backup roll was built to demonstrate the effect of this technique by analysing contact pressure variations and roll profile curves of the backup roll at various heating times. According to the FEM model, the key parameters of the IECT including frequency and current density were optimized based on the simulation results. Compared with the conventional rolling process, the electromagnetic control method on the interference adjustment of the large-size sleeved backup roll is shown to be a possible alternative for a better strip shape with a much longer service life.