Optimization Of Cutter Path In NC Machining

Controlling tool motion by CNC system using path in short lines form will resultin incontinuous machining speed and low surface quality. An optimization process ofcutter path which can increase machining speed and reduce speed fluctuations isproposed in the thesis in order to improve the efficiency of machining and the surfacequality.The optimization process fits short lines with NURBS curves with longer pathand better continuity to increase cutter path length and continuity. The processconsists of the segmenting and fitting stages can transform path in line form into pathin NURBS curve form.The cutter path is segmented into independent parts for the following fittingprocedure, by extracting the characteristic which representing the incontinuity of linepath to reduce the complexity of the curve fitting procedure. Common characteristicsare analyzed to find the criterion of the characteristics which representing theincontinuity of the path.Sample points are selected from the cutter path points in the segmented parts inthe fitting procedure. Using NURBS curve to interpolate the sample points can reducethe amount of calculation in solving control points for the curve. The effects to fittingprocess of using different sampling methods are studied and an algorithm to selectsample points in segmented parts is designed.Path optimization simulations and machining tests carried out on a verticalmachining center show that the proposed approach improves the efficiency ofmachining and the surface quality.