Analysis Of Temperature Fields In Coated Cutting Tools Based On BEM

Metal machining is the most important means in the field of manufacture, cutting tools play very important role. This thesis takes tools with multilayer coatings as research objective. Analytical models for evaluating temperature fields in coated cutting tools were derived. The influence of several different kinds of coating materials and coating thickness on the temperature fields were analysed and compared. Sequentially, the effect of thermal obstacle of coatings was examined and analysed theoretically. The data and results obtained can be used for the rational choose of tool selection.The multi-domain BEM were used to solve two-dimensional heat transfer in coated cutting tools, the whole domain is composed of several homogenous and isotropic subdomains. For each subdomain, boundary integral formulations were satisfied to solve the problem numerically, continuity of temperature and nomal flux at the interface were compensated. All these algebraic equations were assembled and solved simultaneously for the boundary and interface unknown parameters. Once the boundary unknows are solved, integral equations can be integrated to obtain the temperature at any point inside each subdomain.BEM software based on the above formulation has been developed using Fortran programming language under the environment of Compaq Visual Fortran Version 6.5, which was used to simulate temperature distribution. For the purpose of finding the relationship between different coating materials, coating thickness and interface temperature distribution between several classical coatings and substrate. The results of computation demonstrated that the majority of coatings except TiAlN coating have little or no influence on reducing thetemperature distribution within the thickness range of 1～30μm, and when the coating thickness reach to 30μm, the TiAlN coating have the obvious effect of thermal obstacle. Identical boundary conditions were applied to different models with different coating materials. The maximum temperature point on the coating-substrate interface for the TiAlN coating tool was located at the nearest distance from the cutting edge. The temperature gradient on the interface for the TiAlN coating tool was greatter than that of the TiN, TiC coatings and the TiC/Al₂O₃/TiN, TiC/Ti(C, N)/Al₂O₃/TiN composite coatings. The simulated results demonstrate that the BEM can be considered an effective technique for determining the temperature distribution.