Development of simplified analytical model to predict the roll separating force in bar rolling.

Prediction of roll separating force (RSF) is necessary to design new rolling mills, optimise the number of passes and for online control of dimensional accuracy. The intricacy of deformation and complex mixed boundary conditions of velocity and friction makes exact analytical prediction of RSF in a bar or shape rolling quite difficult. Hence, the formula for the prediction of RSF while bar rolling is developed in this research using sticking and slipping friction, assuming the process is equivalent to compression of the simple rectangular bar between two flat plates. The concept of the weak plane strain is also incorporated in the proposed formula. Sinel'nikove's formula derives the contact area between the roll and material. Considering the direct significance of the contact area on the value of RSF, the factors in the said formula are corrected based on a graphical method. Shida's formula is used to calculate the flow stress. The proposed formula is compared with more than fifty distinct experimental findings found in the literature. It is found that the formula is in good agreement with majority of the experimental data. The derived simplified analytical formula can be successfully applied to most types of passes in such industries. [ABSTRACT FROM AUTHOR]