Analytical approximation and evaluation of roll separating force in bar rolling process

Designing the roller and determining the required passes to manufacture the bar depend on the estimation of the pressure value during the bar rolling operation. Numerous researchers have proposed a mean unit pressure formula based on the flat rolling process formula. However, it is challenging to predict the pressure accurately using these formulas. Hence, the principle of sticking and slipping friction as well as weak plane strain is applied to derive the analytical formula based on slab analysis. To apply the proposed formula for different types of passes, the given pass shape is converted into an equivalent rectangular bar and assumed that it is pressed between two flat plates. Prediction of metal flow stress value is calculated by using Shida’s formula with the proposed equation for the correction in input temperature of the hot metal. The constitutive formula of the roll separating force (RSF) is proposed based on these parameters. A comparison is made between the suggested formula and the experimental values which is available in the literature. The findings reveal that the RSF values obtained by applying the suggested method offer a reliable approximation for different kinds of passes.