Research On Tool Orientation Feasible Region For High-precision Curved Surface Five-axis Machining

With the wide application of complex curved surface parts in many fields such as aerospace,automobile,shipbuilding and national defense equipment,ultra-precision machining of the parts is crucial in the development of high-end equipment in major engineering fields in many countries.The geometric structure of curved surfaces parts is complex,and the curvature of the local curved surface changes rapidly.In the actual machining,multi-axis NC machine tools are mainly used for processing.However,with the increase of the rotational freedom of the machine tool and the flexibility of curved surface machining,the complexity of interference problems increases as well.The traditional interference avoidance method can solve the problems of global and local collision.For the curved surface parts with extremely high machining precision requirements,non-linear error,the maximum deviation between theoretical linear interpolation trajectory and actual movement trajectory,caused by the movement of multi-axis NC machine tools rotation axis cannot be ignored.Non-linear error makes the profile error larger,and even the machined surface is difficult to meet the machining precision requirements of parts.The method of error compensation provides an effective way to control non-linear error.However,the tool orientation vector of the compensated machining trajectory does not detect the interference and guarantee the feasibility of the tool orientation vector and the quality of the parts.Therefore,study on the non-interference feasible region method to suppress non-linear error has higher engineering practical application value for tool orientation vector generation.This paper aims to meet the high-precision manufacturing requirements of five-axis NC machining of complex curved surface parts.By restricting the variation range of tool orientation vector,suppress the non-linear error between adjacent cutter contact points.Combined with the tool orientation vector feasible region solution method without interference of single cutter contact points,the profile error of high-precision machining of complex curved surface parts is guaranteed.The method provides effective theoretical support and technical guidance for high-precision machining of five-axis NC of complex curved surface parts.The main contents of this paper are as follows:First of all,according to the analysis of the interference situation in the five-axis NC machining process,the principles of local interference and global interference checking corresponding to different cutter models are established.And the calculation efficiency is improved by dividing the range of interference detection region on complex curved surface parts so as to reduce the calculation amount of interference checking.According to pre-divided angles to check interference,and tool orientation vectors corresponding to cutter angles without interference are selected as single-point feasible tool orientation feasible region.Compared with the previous interference detection methods,the calculation amount is larger and the invalid calculation is more.By reducing the calculation data and other methods,the efficiency of solving the feasible region is effectively improved,which lays a foundation for the establishment of the feasible region for the subsequent constraint of non-linear errors.Then,aiming at controlling the inevitable non-linear error of the rotating shaft of the five-axis NC machining complex curved surface parts,the composition of the cutting error in the actual machining process is analyzed.By determining the tool movement trajectory under different coordinate systems,establish the tool path equations of theoretical ideal movement trajectory and actual movement trajectory between adjacent cutter contact points in the five-axis NC machining.Thus the actual cutting error between adjacent cutter contact points is solved and the relationship between the movement of machine tools rotation axis angle and the cutting error in the five-axis NC machining is established.Combined with the single point non-interference feasible region of complex curved surface parts,the feasible region of tool orientation vector for five-axis high-precision five-axis machining is obtained.According to the proposed feasible region,generate the machining tool orientation vectors and the experiments verify that the tool orientation vector generated by the proposed method can effectively improve the machining quality of parts.Finally,Computer aided manufacturing software for tool orientation vector selected in high-precision feasible region by five-axis NC machining is developed.A GUI is created through the graphical user interface development environment and set up 5 function modules.The function of surface fitting,cutter model establishing,detection points region division,and interference checking principle are established.The five-axis machining single point non-interference feasible region is determined.The function files of the machine tools rotation axis movement angle calculation,tool orientation angle transition and different coordinates transition are compiled.The NC machining programs of cutter contact points and corresponding tool orientation vectors for the whole surface are output.The application of the high-precision feasible region in practical five-axis NC machining is significant.The tool orientation feasible region solution method for high-precision curved surface five-axis machining in this paper can significantly suppress non-linear error,avoid the local and global collision and improve the processing quality.The method provide a certain reference for further research on tool orientation generation of complex curved surface parts,and at the same time,lay a foundation for realizing high precision machining of complex curved surface parts.