Modeling machining errors for thin-walled parts according to chip thickness

In the milling process of titanium alloy thin-walled parts, because of its low stiffness, processing deformation easily occurs, which results in in low-dimensional accuracy of machined surface and affecting the workpiece performance. Cutting force is the main factor that causes cutting deformation. Cutting deformation also affects cutting force. There is a coupling relationship between them. To solve the above problems, a method is proposed to predict the surface error by calculating the milling force by varying the chip thickness and by coupling the force with the elastic deformation of the workpiece. Firstly, the analytical model of bending elasticity deformation of thin-walled parts is established. Then, the micro-unit entrance angle and instantaneous chip thickness are calculated by the contact relationship of workpiece deformation and the chip boundary decision conditions. The cutting force and workpiece deformation at random rotating angle are obtained by iterative calculation method. Finally, the surface error is predicted by calculating the deformation matrix and the principle of surface generation mechanism. The simulation results are in good agreement with the experimental results, which verifies the accuracy of the proposed method. The results provide theoretical support for milling process optimization and profile accuracy control of titanium alloy thin-walled parts.