Study On Tool Deflection Error In Contour Surface Milling

Contour surface machining plays an important role in the aerospace, automotive, mold and other industries, improving the machining precision of the parts with contour surface is our unremitting target. The traditional process planning only considers the geometry of workpiece and tool during the machining, but ignores the physical factors such as the cutting force and the tool deflection. In order to avoid the phenomenon of overload, vibration etc., conservative cutting parameters are usually used in actual production, so that the productivity is limited. The results of many studies show that the error from tool deflection cased by cutting force is the main source of machining error in no thin-walled parts machining.In this paper, milling contour surface is the object of study, and the main contents are as follows:(1) Based on the differential method, the end mill is discretized into a series of disk with micro-thickness along the axis of cutter, and the cutting edge is discretized into a series of cutting elements. Considering the cutting and ploughing effects in milling, the mechanical model of cutting force with end mill is established. The cutting coefficients of the model are identified and the model is verified by the flat slotting machining test.(2) The end mill is regarded as a cantilever beam with structure differences, and the segmented cantilever beam model is used for predicting the tool deflection. The precision of the cantilever beam model is analyzed by comparing with concentrated force and dispersion force respectively, the tool deflection model is built with dispersion force. The deformation coefficients of the tool deflection model are obtained and the model is proved by the hanging test.(3) Different from flat plane milling, the chief features of contour surface milling include the changes of cutter feed direction and contact angle between tool and workpiece. For the contour surface milling, firstly the milling process is discretized into a series of micro-cutting segments, for each micro-cutting segment, the feed direction is determined by the start and end position of cutter motion, and the contact angle is gained by the intersected points between the cutter geometry and uncut part profile.(4) The tool deflection error is the result of equilibrium between cutting force and tool deflection, the effect of the cutting force caused by the tool deformation should be taken into account when predicting the tool deflection error. So based on the interaction of cutting force and tool deformation the flexible cutting force model is established, after that, tool deflection error are predicted with generated mechanism of error,. At last, a test of free contour surface milling is carried for verifying the tool deflection error model.