Research Of Tool Path Calculation Method Of Five-axis Flank Milling For Integral Impeller

Integral impeller is the key component of all kinds of turbine machinery such as aerospace engine and marine engine, with the improvement of requirements of engine performance, the shape of the integral impeller becomes more and more complex and its processing is becoming more and more demanding. Five-axis flank milling machining is an important means of efficient processing the complex high performance parts in industry, it can be used to machine the continuous, smooth and complex surface. Due to the exist of principle error when flank milling the undevelopable ruled surface, the complexity of tool path planning becomes higher. Therefore, in the area of five-axis flank milling of integral impeller, the study of cutting tool path planning has important practical significance.This paper has analyzed the geometry principle of flank milling the undevelopable ruled surface theoretically. Based on the character of the isometric mapping in differential geometry, the tool path planning of five-axis flank milling for undevelopable ruled surface is studied. The main contents are as follows:1. The relationship between surfaces and the individual characteristics of the surface is discussed by applying the differential geometry curves and surfaces theory. Aims at the interaction contact between the surface, the geometry principle of flank milling for surface and cutter axis vector geometry kinematics are studied and be applied to establish the kinematics model of cutting tool envelope surface.2. Considering the contact characteristics between tool surface and processing surface, the local geometric model of machining curved surface with rotary cutting tool is established, and the principle error of the undevelopable ruled surface flank milling is analyzed; The blade surface and other important surfaces of the processing are analyzed and the blade is represented by the NURBS method; The milling process is planned, mainly including the processing stage division and the selection of cutting tool.3. To do the tool path planning of five-axis flank milling process for the blade, feeding step length calculation method is put forward based on the curvature change; In view of the cylindrical milling cutter, the equidistant surface of design surface is built up according to the theory of poor invariance under the isometric mapping in differential geometry, the error between tool envelope surface and designed surface can be converted to the error between the tool axis trajectory surface and equidistant surface. The final tool is determined by controlling the error between surfaces; For conical milling cutter, the tool position calculation method is put forward based on the characteristic of line offset, and the tool axis trajectory surface was optimized based on the new offset surface.4. To make the analysis of error caused by a variety of processing methods, in this paper, the superiority of the proposed algorithm is proved by an example, then its feasibility is verified by processing simulation, and its trajectory smoothing is judged. It can be indicated that the established model can reduce the machining error, and it can improve the efficiency of processing to some extent, which is of practical significance.