| With fixing under point support, thin parts tend to be deformed under the clamping force, cutting force, cutting heat, and thermo-mechanical effect in the process of machining. The internal residual stress and the as-machined residual deformation deteriorate the final machining precision. It is really difficult to guarantee the dimensional and geometric accuracy of the workpieces under this situation.In this study, the reasons for deformation of thin part fixed under point supports were analyzed, and device enabling online recording of clamping force was designed. In order to find the variation of the clamping force, milling experiment with three kinds of materials(steel 45,steel Q235 and aluminum alloy 6061) was conducted. Based on the analysis and experiment, two clamping methods for controlling the deformation of thin parts were proposed, namely "constrained by dual-point clamper" method and "two support points" method.Research on "constrained by dual-point clamper" method. Based on the Generalized Principle of Superposition Method, a mathematical model considering the deflection from both cutting forces and clamping forces has been estimated and compared with the traditional clamping scheme. Both 3D finite element model (FEM) based simulation experiments and experimental case studies are carried out, and their results show good agreement" with each other. The deflection computation and prediction from numerical studies indicates the efficiency and correctness of the proposed approach.Research on "two support points" method. Based on the analysis of the finite element method, a two dimensional model of cutting process was built with Abaqus. Deformation and internal stress distribution is studied for different fixing. For traditional clamping scheme, the thin part has a large deformation caused by internal stress uneven distribution. Milling experiment with aluminum alloy 6061 was completed to verify the effectiveness of the proposed approach. |
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