Determination of the heat transfer coefficient at the workpiece-die interface for the forging process

This paper describes an investigation of the determination of the heat transfer coefficient at the workpiece-die interface for the forging process. A surface thermocouple has been constructed to measure the temperature at the die surface, where a high pressure occurs, for the simple upsetting forging process. The process was also simulated by a commercial finite element package. The measured and predicted temperatures were then used in an inverse algorithm with an iterative approach to determine the interface heat transfer coefficient (IHTC). The results show that the predicted temperatures modelled by a constant IHTC at the rest-on-die stage were in good agreement with the experimental measurement. However, for the forging stage, the IHTC values vary significantly during the process. This has important consequences in the implementation of simulation software.