An iterative numerical method for determination of temperature-dependent friction coefficients in thermomechanical model analysis of cold bolt forging

摘要

A set of temperature-dependent friction coefficientswas developed to increase the accuracy of finiteelement (FE) simulations of cold bolt forging. The initiallyattained friction coefficients at different temperatures werecalibrated with the iterations between the experimental andthermomechanical model extrusion test loads. The constantfriction coefficient and the determined set of friction coefficientsas function of temperature were then implementedto the simulations of the cold bolt-forging processes. Furthercalibrations and model validations were made based on thetemperature measurements of the workpiece in the actualbolt-forging processes. To show the advantages of developedtemperature-dependent friction coefficients, the loadsof four different bolt-forging processes were compared withthe thermomechanical model loads calculated using theconstant friction and temperature-dependent friction coefficients.The modeling results indicated that the use oftemperature-dependent friction coefficients in the FE simulationsresulted in nearer temperature distributions and theloads of the workpiece during forging as compared with theuse of a constant friction coefficient.