The consideration of temperature effects on the numerical analysis of forging problems is very important. In this study, a program is proposed, which is based on the rigid plastic finite element method coupled with the thermal analysis for forging processes. This program can also be applied to the thermal analysis of dies under continuous operation.

On the other hand, the accuracy of the numerical simulation in forging processes depends on physical parameters used in the analysis. In particular, the interface heat transfer coefficient between a workpiece and a die is very important. A practical method is also proposed to measure the interface heat transfer coefficient quantitatively. The interface heat transfer coefficient can be determined by comparing calibration curves with temperature measurements in simple compression tests. The calibration curves are derived from the thermal analysis by the finite difference method. The effects of lubricants, the initial weight of the lubricants, the temperature, and the contact pressure on the interface heat transfer coefficient are evaluated. The interface heat transfer coefficient obtained by this method is applied to the coupled analysis of warm forward rod extrusion. The die temperature obtained by the numerical analysis shows good agreement with that in the experiment.
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