Finite difference analysis of the thermal behaviour of coated tools in orthogonal cutting of steels

摘要

Temperature measurement and prediction have been a major focus of machining for several decades but now this problem became more important due to the wider use of advanced cutting tool coatings. Practically, there is a lack of simulation programs for prediction of the temperatures in the cutting zone when machining with differently coated cutting tools. In all literature items cited the finite difference methods (finite difference approaches) were used to find the distribution of temperature inside the uncoated tool body or along the tool-chip interface for continuous (turning) and interrupted (milling) machining processes. The algorithm applied overcomes this limit. In this study, a special variant of the finite difference method called the method of elementary balances (MBE), in which difference equations are defined based on balances of energy produced for all discrete elements of the model, is proposed to predict the tool temperature fields in continuous (orthogonal) machining of AISI 1045 steel with uncoated and coated carbide tools. These predictions provide a detailed view of the changes in the two-dimensional thermal field inside the tool body as a function of cutting speed for the defined friction conditions and values of the heat partition coefficient. Special attention was paid to temperature distribution curves at the tool-chip and work-flank interfaces and possible sources of computed errors. The computed results were compared with the selected experimental values to verify the accuracy of the simulation technique used.