Research On Tool Deflection Error Compensation In Millingof Splicing Mold With Convex Surface

The development and manufacture of automobile panel die accounts for about 66% of the total development cycle of automobile.However,due to its large volume and complex surface,automobile panel dies are usually machined by whole milling after splicing hardened steel with different hardness.In the process of machining,the impulse load exists at the splicing seam,which leads to tool wear too fast and abrupt change of milling force.It causes serious tool deflection error and low precision of workpiece profile.Therefore,in this paper,the tool deflection error compensation in the milling process of convex surface splicing die is studied.The purpose is to improve the machining efficiency of automobile panel splicing die,and the surface accuracy of the die can be effectively controlled.First of all,according to the structural characteristics of convex surface splicing die,a complete milling force model of convex surface splicing die was established by combining shear force model,friction effect force model and impulse force model.According to the spatial position relationship between the tool axis and the splicing seam,the undeformed chip thickness at the splicing seam was divided into regions.Thus,the shear force model the shear force model was obtained.The functional relationship between the tool flank wear and friction effect force was constructed by the micro-element method.In this way,friction effect force model was established.By introducing a single-free Italic collision model,the impulse force model at the splicing joint was obtained.Finally,the accuracy of the model was verified by the milling experiment.Second,based on the milling force of the splicing die with convex surface,the deflection model of the tool holder-tool system was established.The deflection model of the system was established by the piecewise rigidization method for the tool holder and tool respectively.The influence of the joint surface of the tool holder-tool system on the deflection was also considered in themodeling.Finally,the predicted results of the system deflection was compared with the experimental results.It proved that the deflection model of the tool holder-tool system can accurately predict the system deflection.Once again,based on the deflection model of the established tool holdertool system,the tool deflection errors in the milling process of convex surface splicing die was predicted.The regularities of distribution of tool deflection errors at different processing inclination angles and splicing seams was analyzed.The tool deflection error was compensated off-line by modifying the tool path.The experimental results showed that the tool deflection error after compensation is significantly lower than that before compensation.This method can effectively control the accuracy of the splicing die with convex surface.Finally,the visual operation interface of predicting milling force,deflection of tool holder-tool system and tool deflection error in the milling process of convex surface splicing die was developed by MATLAB.By inputting the corresponding machining parameters,the distribution of cutting force,deflection of tool holder-tool system and tool deflection error in milling process of splicing die with convex surface can be obtained rapidly.The visual operating platform provides the possibility for quick off-line compensation of tool deflection error.