Development and verification of a computer model for thermal distortions in hard turning

It is well established in metal removal processes that the primary heat source is the deformation work and friction in the contact zone between the workpiece and the tool, which cause the temperature to increase. In order to control the temperature cutting fluids are used to reduce friction and to remove the heat from the work zone. Heat removal is a particularly difficult problem in hard machining, where the cutting process normally takes place without cutting fluid. A finite element method-based computer model, developed for the simulation of thermal deformation in multi-pass turning has been adopted and experimentally verified in dry cutting of hardened steels. The paper presents novel theoretical and experimental solutions to establish model parameters in order to ensure adequacy of the model to real heat transfer process in hard turning. This new inverse problem solution (IPS) technique was applied to obtain the heat generated by the cutting process and the heat transfer coefficients from the workpiece to still air and forced air. The predicted results for workpiece temperature field and workpiece accuracy are in good agreement with the measured data.