Análise de problema inverso não linear em transferência de calor para o estudo da ferramenta de metal duro revestida e não revestida

Abstract

This work presents the thermal influence of the coating in a carbide cutting tool. The influence of the convection is also included in the analysis. The thermal model consist of a carbide cutting tool, a shim and a tool holder. This model is represented by the three dimensional transient thermal diffusion equation which is solved by the FEM (Finite Element Method) through the software COMSOL Multiphysics® 5.6. The most impor tant advantages of using this software is the easy way to model the thermal coating, whose thickness is in the order of (𝜇m). For the coating, a cutting tool coated by Tita nium Nitride (TiN), Aluminium Oxide (Al2O3) and Titanium Carbo-Nitride (TiCN) was chosen. This model is subjected to the boundary conditions of convection and radiation in the regions exposed to the environment. Boundary condition of prescribed heat flux in the contact area between the cutting tool and the workpiece. The thermal proper ties adopted in this work are temperature dependent. This is possible due the non-linear Function Specification technique used to solve the inverse problem. In order to obtain experimental data, 13 turning experiments were performed in nodular cast iron sample. Eight experiments were done for the uncoated tool, 7 dry experiments and 1 with pressure air cooling. For the coated tool, 5 experiments were performed, 4 dry experiments and 1 with pressure air cooling. In all experiments termocouples temperatures, thermal camera temperatures and dynamometer forces data were aquired. An exploratory data analysis of the experimental data was done. The heat flux is estimated through a MATLAB® script together with COMSOL® , using the tool MATLAB livelinkTM. Once the heat flux is obtained, COMSOL® is used again to generate the temperature thermal gradient for the whole model. Numerical results such as: Maximum temperature in the contact area and temperature field for the coated and uncoated tool were obtained. A comparaison be tween the numerical and experimental results for the thermocouples were also performed. The results showed an increase in the heat flux and in the maximum temperature in the contact area for the coated tool in comparison with the uncoated tool.