Research On Contour Of Backup Roll For5000mm Wide Plate Mill

Since the operation and maintenance for back-up roll is backward in technology,issues of the large heavy plate mill back-up roll occur more frequently. It seriously affectsthe life of back-up roll and equipment productivity. Contact pressure concentration existsin the edge of back-up roll when the large heavy plate mill works. The fatigue of stresscauses hardening on the roll surface.The hardening in the edge is more severe than that inthe middle, which causes fatigue cracks appear in the edge of back-up roll. With thecrack growing, roll spalling problems will occur.This paper takes the5000mm4-high rolling mills as the object of study. It firstlyanalyzes the stress state between back-up roll and work roll by using the Hertz contacttheory. The Hertz contact theory only considers static load normal pressure, withouttaking into account the tangential force. So this paper also discusses the roller contactarea by using the theory of rolling and analyzes the micro-slip phenomenon betweenrollers by the knowledge of the micro-tribology.An approach to prevent premature failure of a backup roll is to design a reasonablecontour of back-up roll, without changing the structure of the existing mill and affecttingthe production schedule. A reasonable contour of back-up roll can equalize contactpressure distribution and reduce edge stress concentration. Therefore, this paper propsesa new back-up roll contour through considering several existing back-up roll contour, andestablish a3-D finite element rolling model of the4-high mill by using finite elementsoftware ABAQUS to compare the stress field, bending deformation and plate shapebetween the new contour and the existing contours. The result obtained by ABAQUS canprove that the new contour can effectively reduce localized stress and bending deflection,and can improve the quality of plate shape.Finally, this paper describes the fatigue-related knowledge, and estimates the fatiguelife of the new and the existing contour back-up roll by using a local stress-strain methodand FE-SAFE fatigue analysis software with the previous results of the finite elementstress analysis. The result of fatiue life estimation proves that the new contour of back-up roll can effectively improve the service life of back-up rolls.