FINITE-ELEMENT CALCULATION OF THERMAL COUPLING BETWEEN WORKPIECE AND TOOLS IN FORGING

A finite-element model for calculating the die temperature profile for a hot-forging operation is presented. The workpiece is modelled as a thermo-viscoplastic material, while the dies are considered undeformab le. Heat transfer between the dies and the workpiece is modelled using an iteratively coupled, fixed-point calculation of the temperature in each domain. Transfer of temperature boundary conditions across conta ct interfaces is performed for non-coincident meshes, using a boundary integration point contact analysis. Two industrial-type examples are presented. In the first example, the effectiveness of the transfer of the temperature boundary conditions for a non steady-state forging pro cess is evaluated and determined to be satisfactory. Then weakly- and strongly-coupled temperature resolutions are compared. It was found th at the strongly-coupled resolution may be necessary in order to obtain reasonably accurate results. In the second example, the weakly-couple d resolution is compared to a constant-temperature die approach for a relatively slow forging process, which shows the influence of the die temperature on the flow of the material.