Research On Deformation Prediction Of Five-axis Machining Thin-walled Complex Surface

With the widespread applications of high performance thin-walled parts with complex surface that the engine blade represents in the high-end equipment manufacturing fields of aerospace, power and traffic, a higher requirement of machining accuracy and surface quality is put forward. In the machining process of these parts with the properties of thin wall, low rigidity, difficult-to-cut material, high material removal rates and complex surface form, the machining deformation errors induced by the cutting force are more likely to lead to a non-negligible deviation between the desired and machined surfaces, which in turn may possibly affect the product’s performance and stability. However, the machining efficiency is decreased greatly by using the traditional machining-measurement-machining method. Thus, deformation prediction of machining thin-walled surface has engineering significance and growth potential in process optimization and machining error compensation. Hence, in this paper, the technical means of the digital modeling, finite element simulation and experiment verification are combined together to conduct the research on deformation prediction of five-axis machining thin-walled complex surface. The main contents are as follows:A cutting force prediction model is established for ball-end cutter in five-axis machining surface. Based on the analysis of the kinematics transform relationship in5-axis machining and the cutting edge geometrical model, the mathematical model of the cutting edge motion trajectory is described, then the calculation of undeformed chip thickness generated by the previous and current cutting edge tracks and the cutting force prediction model for5-axis ball-end machining are presented. Meanwhile, the method for judging the engaged cutting edge elements by Z-map model based on triangular patch is introduced, and the formula derivation of the cutting coefficients is conducted. Then, the comparison between measured and predicted cutting forces verifies the feasibility of the proposed cutting force model.The method of deformation prediction of five-axis machining thin-walled complex surface is proposed. The precise mesh generation means with hexahedron elements for surface part are introduced, and then in order to load cutting forces dynamically and remove material continuously, a rapid extraction algorithm of simulation information is presented, which is suitable for tool path driven by zig, zigzag or spiral in machining surface. After the machining deformation theory is investigated, the method to update the cutting forces under the machining deformation is given, and the flexible iterative deformation prediction algorithm in5-axis machining thin-walled complex surface is proposed based on the cutting balance. And the case of machining titanium alloy TC4thin-wall blade is performed to provide basis for the following verification of this proposed method’s feasibility.Finally, with titanium alloy TC4thin-wall blade, the verification experiments including blade machining and error measurement are conducted under the proposed machining process. The comparison results illustrate that the predicted values are in good agreement with the measured one, and the prediction precision is within0.03mm, which validates the feasibility of the proposed prediction method.