Prediction of the wear profile of a roll groove in rod rolling using an incremental form of wear model

Abstract

A model for predicting the wear profile of the ductile cast iron roll during rod (or bar) rolling is proposed using Archard's wear equation. Archard's wear equation was reformulated as an incremental form and the hardness of the roll was expressed as a function of rolling time under a high temperature. The wear profile of the roll is calculated at each deformation step by consideration of relative sliding velocity and normal roll pressure at contact area. The coefficients required in the proposed wear model have been obtained using the high-temperature wear tester of pin-on-disc type. A three-dimensional finite element analysis coupled with the proposed wear model has been carried out for the oval-round pass rolling sequence widely used in present continuous rod (or bar) rolling mills. To describe the deformation behaviour of material at the roll/material interface better, a contact-searching algorithm that can be applied efficiently to the finite element mesh was also suggested. The results showed that, for an oval groove, the maximum wear occurs at the centre part of the roll and, for a round groove, at the shoulder area of the roll. The wear profiles moves to the spread direction of workpiece (i.e. roll axis direction) as well as the direction of roll centre as the production (tonnage) increases. The proposed wear model might be used for adjusting the gap (pass height) of rolls to set up a suitable rolling schedule for keeping dimensional tolerance of the product and avoid catastrophic failure of rolls after rolling a characteristic tonnage.