Estimações das temperaturas no torneamento usando problemas inversos em medições por termovisor e termopares

Abstract

Machining plays an important role in the manufacturing of mechanical parts. This work analyzes specifically the turning, which is one type of the machining processes. When it is studied the general aspect of turning, one realizes high efforts acting on the cutting zone. The high efforts along with the small dimensions of the insert-chip contact area contribute to the development of high cutting temperatures. Furthermore, the temperature is an important factor associated with the wear of cutting tools. The focus of the work was to analyze the temperatures developed at the insert-chip interface. It was used in the analysis a model assembling the shim, tool holder, clamp and cutting tool. This model was represented threedimensionally. The solution of the problem was divided into two parts: one applying inverse techniques, and another with the solution of the direct problem. It was used as inverse techniques the Nonlinear Function Specification Method (NFSM) and the Time Traveling Regularization (TTR). These techniques were applied by using LiveLink for MATLAB®, which integrates COMSOL® with MATLAB®. The direct solution of the problem relates to solving the three dimensional non-linear transient diffusion equation. Among the boundary conditions of the direct problem, one is the heat flux imposed at the insert-chip contact area. This heat flux is essential for the solution of the problem. In general, this heat flux allows the direct problem to estimate temperatures; these estimations are then applied into the inverse problem and compared to experimental values of temperature. Comparing the estimated temperatures with the experimental ones provided new information about the heat flux, which was updated and again used into the direct problem. For the experiments it was used an insert of cemented carbide. Thermocouples and a thermal imaging camera were used for temperature measurements. The results of the simulations were analyzed and compared to experimental values. Comparisons were made between the heat flux values estimated by the NFSM and by the TTR. In addition were highlighted the differences in estimations regarding the use of thermal camera or thermocouples in the inverse problem approach.