Cross-directional Feed Rate Optimization Using CL Surface

With the state-of-art technologies,NC tool-paths are optimized along the direction of the tool-path(feed direction)without the consideration of the consistency in the crossing(step-over)direction.This may cause the the DEC./ACC.regions distributed randomly at the crossing direction on the tool-path surface and there might be variation of feed rate between the adjacent tool path.As a result,the surface finishing is not fully optimal.In this thesis,a method that performs the feed rate scheduling with consistency in crossing direction is proposed.The core of the method involves three steps: cross-directional information reconstruction,feature curves construction,and feed rate computation.In the reconstruction of cross-directional information,the neighbor projection,which is the nearest point on the adjacent pass-segments of the tool path,of each CL point is found.In feature curves construction,feature points are identified and connected into curves along the crossing direction based on the neighbor projection.In feed rate computation,tool path is divided by the feature curves into feed rate intervals.According to the reconstructed crossdirectional information,the target feed rate of each feed rate interval are smoothed along the crossing direction.Finally,the feed rate computation result is output to the online CNC system.Above algorithms are integrated into a software package.Experiments and simulations on two parts are carried on to verify the effectiveness of the proposed cross-directional feed rate optimization method.Simulation results shows that,comapred with the tool path without cross-directional optimization,the optimized tool path shows good feed rate consistency in both crossing and feed direction,especially in the feature area.The experiment results also prove that our algorithm can effectively improve the quality of the machined surface,especially in the feature area,correspondingly.