Study Of The Algorithm Of Interference-free Tool Trajectory Generation Of Complex Surface

An impeller is one of the typical complex surface parts. It has complexgeometries of thin blades, large distortions and small gaps between blades,and the tool is likely to collide with blades. Because of the superiorperformance of the five-axis tool machine, such as high-efficient and highquality, the impeller is mainly produced by Five-axis machining method.Only to generate high-quality NC code, the quality of impeller is promised.And interference-free tool trajectory generation is one of the key factors ofgenerating high-quality NC code. This paper studies the algorithm ofinterference-free tool trajectory generation for the impeller of five-axismachining. The details are as follows.Firstly, the geometric properties of complex surface are analyzed, andunit normal vector, the maximum and minimum of normal curvature andtheir directions, etc. are calculated. On this basis, iso-parametric andiso-scallop tool trajectory generation methods are mainly discussed togenerate tool trajectories of blades. Then, compare such two methods differsfrom algorithm itself, the trajectory generated length and actual scallopvalues cross the surface. The result indicates that iso-scallop tool trajectorygeneration method has higher efficient and better quality of the machinedsurface.Tool orientation determination is another aspect of interference-free tooltrajectory, which can promise to make full use of the superiorities offive-axis machining and avoid interferences between tool and other objects.This paper presents two methods to plan the tool orientations, one is theguide curve method, and the other is the smoothing interpolation method ofthe key tool vectors. For the guide curve method, according to the geometricstructure of impeller, a guide curve between adjacent two blades isconstructed. Suppose tool orientations are determined by the vector starting from the guide curve point and ending at the CL point. Now, the keyproblem is how to calculate the guide point. The guide point is obtained byasking the guide point with u parameter of surface at the CC Point. Aftercalculating the axes vectors, tilt angle and yaw angle are obtained. The resultshows that tool can swings are feasible and easy to be realized. For thesmoothing interpolation of the key tool vectors, several key tool vectors areset according the geometric structure of impeller. Then, an improvedquaternion interpolation is using to smooth these key tool vectors. The resultshows that the tool can swing smoothingly.A user software module is developed to integrate the proposed methodsinto the commeriacl CAD/CAM system UG NX. It is easy to use thisdeveloped software to generation interference-free tool trajectory. Only toset the cutting parameters, tool patameter and select surface to be machined,the user software module can generation interference-free trajectoty. Finally,A flat-bottomed blade is machined to verify the effectiveness of thealgorithm of interference-free tool trajectory generation.