Simulation of Screw Rolling Processes at Constant and Variable Friction Along the Contact Surface Between Roll and Billet

Computer simulation of the processes of three- and four-roller screw rolling was performed using the QForm finite element analysis computing environment with a constant and variable friction factor for roll–billet pairs. Simulation results at a constant friction factor showed that in the longitudinal section of the billet after four-roller rolling, the average value of the accumulated deformation is higher compared to three-roller rolling, and the deformation penetrates deep into the billet. The results also showed that four-roller rolling proceeds faster than three-roller rolling with a constant and variable friction factor. An analysis of the estimated speed of the billet movement during three- and four-roller rolling revealed that the return to a stable process after a sharp decrease in speed occurs faster in four-roller screw rolling than in three-roller rolling due to insufficient friction between the roll and the billet.