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Cutting temperature during high speed machining operation has been recognized as a major factor that influences the tool life, the machined surface integrity and its quality. It has been an important research project. In the paper, the heat transfer model of cutting temperature field has been built. Theoretic study about shear plane heat source and tool-chip interface friction heat source is carried out with the method of heat source. The temperature field distribution of chip and workpiece due to shear plane heat source is determined by this method. The temperature field distribution of chip and tool due to tool-chip interface friction heat source is also obtained. Then temperature field distribution of chip and tool due to combined both sources is derived. This paper builds thermo-viscoplastic model and carries out the finite element simulations of cutting temperature field by finite element software. The temperature field distribution indicates that the highest temperature focuses on the local region near to the tooltip at the tool-chip interface. From the dynamic cutting simulation, the curve of the highest temperature variation with step indicates that at the early stage of cutting, temperature increases very rapidly and its change is slower and slower during cutting period until reaching steady state. When reaching steady state cutting, the temperature variation curve of machined surface along cutting depth direction indicates that the temperature only a thin layer of work piece rise while the local workpiece temperature doesn’t change much. During steady state cutting process, the maximum temperature occurs away from the tooltip rather not the tooltip can be obtained from the rake face temperature curve of the tool-chip interface. The effect of the cutting parameters such as cutting velocity, the cutting depth, rake angle on the cutting temperature has been studied. The computed conclusions show good agreement with those of literatures.
High-speed machining (HSM) technology, with high cutting velocity, high feed rate and perfect surface quality, is one of the most advanced technologies developed promptly in the last 20 years. HSM is the direction of advanced manufacturing technologies, and is one of the domains that have been studied most in the science and technology and industry fields. Cutting force is the basis to calculate cutting twist moment and power, and it is essential to analyze cutting heat and temperature hoist, and to study machining precision and surface quality of products. With the rapid development of computer technology, the numerical simulation method has become an important instrument. Because of the complexity in HSM process, using only one method to study cutting force is not enough. Accordingly, on the basis of metal cutting theory and elastic-plastic mechanics, FEM is used to analyze the stress-strain relation in cutting zone, and to discuss the influences of various cutting parameters on cutting force. At first, according to the characteristic of HSM, orthogonal cutting model is established, and formation mechanism of cutting zone, forces that chip suffered, friction characteristic of cutter/workpiece area, and shear angle are analyzed. Establish finite element model, and use elastic- plastic mechanics to discuss stress-stain state of elastic and plastic deformation in cutting zone. Pay attention to the material model, meshing, boundary condition, and chip separation criterion of the model, which can affect calculation precision directly. In simulation, the influence of rake angle, cutting speed, feed rate, and cutting thickness on cutting force are discussed. At last, high speed milling experiments are conducted. One-factor experiments are adopted to validate the finite element model and multi-factor orthogonal experiments are designed to validate the influence of cutting conditions on cutting force.
The research of HSM mechanism, which is the theoretical fundamental of high-speed Machining (HSM), is critical for application and development of HSM technology. Surface quality, an important research content of HSM mechanism, is judged by residual stresses. Residual stresses in machined layer for HSM impact the working performance and fatigue strength of parts. Also, they are major affecting factors of defects such as deformation and crack. As a result, correct prediction of residual stresses in machining process has great theoretical significance and practical values. The theory of residual stresses in machined layer involves many cross subjects，such as mechanical manufacture, elastic-plastic mechanics, finite element method and etc. In view of the complex nature of problem，a method including experiments, theoretical modeling and computer simulating is proposed in this dissertation. Then, beginning with the metal cutting principle, deep theoretical researches and numerical simulations of residual stresses in HSM are carried out, and a predicting model is established. This is an important fundamental subject to promoting HSM technology development and application, which has a very important theoretical and practical significance to exploit HSM potential energy further. In this paper, firstly, the generation mechanism of residual stresses for machining is analyzed, the analytical model for the formation mechanisms of machined layer is established, and a thermo-mechanical coupling equation for the third deformation zone is constructed. Secondly, the distribution of residual stresses on machined layer and effects of machining parameters and tool geometry on residual stresses are studied, by the use of FEM procedure. Thirdly, experiments of high speed milling and residual stresses measurement are carried out in order to study the distribution of residual stresses and to verify the availability of FEM models. At last, a mathematical model of relationship between residual stress and affecting factors is promoted.