Mechanism of residual stress superposition in milling process of thin-walled parts and comprehensive deformation control method

The processing deformation of thin-walled parts is difficult to control under the traditional process method because of the small rigidity of the parts and the large amount of removal. Simulation research of various process parameter combinations and engineering test are carried out for the typical thin-walled parts with 2mm wall thickness and diameter-thickness ratio more than 850 to solve the problem of deformation. Based on the umbrella-shaped special tool of YG8 tungsten steel, the influence of process parameters on the important indexes and distribution law of residual stress of thin-walled structure parts were studied. Residual stress superposition mechanism of process parameter combinations of semi-precision milling and fine milling are revealed. A process design method considering the deformation control objective of thin-walled parts is proposed. The method includes the principle of high-speed machining, the design criterion of process allowance considering the location deviation, and the optimization design method of process parameters and their combinations based on the high-speed and allowance allocation criterion, in order to improve residual stress and its distribution, reduce cutting deformation and the long-term stability of the thin-walled structure. The relative cross-section size, thickness, roundness and concentricity of thin-walled parts with conical surface were measured by roundness meter and CMM. Result reveals that the use of high-speed milling and the optimized combination of process parameters can effectively control residual stress and deformation.