Generation And Optimization Of Tool Trajectories For Five-axis Flank Milling

In the filed of mechanical manufacturing, research on machining complex free formsurface, such as impeller of aircraft engine, screw propeller for boat, impeller of steam tur-bine, has been an area of focus for several years. Generally speaking, ball-end milling is themost spread technology currently used for free form or sculptured surface machining owingto the simple toolpath generation and wide range of applications, nevertheless the very poorprocessing efficiency and surface quality increases costing. To overcome the shortcomingsof ball-end milling, flank milling(or called side milling) is adopted. However it is main-ly apply to ruled surfaces,and we cannot machine a ruled surface exactly unless the ruledsurface is developable. Through research on the generation and optimization of tool trajec-tories, the cutter deflection will be decreased to satisfy the accuracy requirement. There aremany commercial CAM softwares for implementing such functionality, Such as MAX-5T M.With MAX-5’s patented algorithm,80%to90%cutting errors will be decreased. Thereforeresearch on the generation and optimization of tool trajectories play a significant role inpromoting the development of the manufacturing of China.This thesis starts the discussion from differential geometry, the intial toolpaths are cal-culated by a kind of numerical methods. A method to approach and escape motions isproposed. The tool envelope surface is generated by quaternion interpolation and two-parameter family of spheres. Compute the signed distance which is considered to be thecutter errors between design surface and the swept surface. Factors such as tool parameterscorrelate with cutting errors have been discussed.Calculate the tool trajectories in manufacturing coordinate system by mapping modelcoordinate system to manufacturing coordinate system. Generated NC code through postprocessing, then verify the tool paths by simulation program. Then machining the ruledsurfaces in five-axis machining center, inspect the results with the usage of touch triggerprobe by a on-machine measurement system.In order to reduce more cutting errors, global optimization method of tool path is pro-posed by signed distance function. Then, analyze the twist of a non-developable ruled sur-face. The method to mill it by strips is proposed, simulation and experiment results showthat the method is effective.In the end of the thesis, algorithm of flank milling arbitrary free surface have been onresearch. A Be′zier surface is approximated by piecewise ruled surfaces. Then flank millingis used to manufacture the Be′zier surface. At the same time, point milling is also used to manufacture the same surface with the help of CAM software, inspect both on-machinemeasurement system. It can be seen from the comparison that, flank milling the free surfaceusing piecewise ruled surface approximation could meet accuracy requirements, and bettersurface quality obtained.