数控加工刀位轨迹优化处理(5)

Abstract

Controlling tool motion by CNC system using path in short lines form will result in incontinuous machining speed and low surface quality. An optimization process of cutter path which can increase machining speed and reduce speed fluctuations is proposed in the thesis in order to improve the efficiency of machining and the surface quality.

The optimization process fits short lines with NURBS curves with longer path and better continuity to increase cutter path length and continuity. The process consists of the segmenting and fitting stages can transform path in line form into path in NURBS curve form.

The cutter path is segmented into independent parts for the following fitting procedure, by extracting the characteristic which representing the incontinuity of line path to reduce the complexity of the curve fitting procedure. Common characteristics are analyzed to find the criterion of the characteristics which representing the incontinuity of the path.

Sample points are selected from the cutter path points in the segmented parts in the fitting procedure. Using NURBS curve to interpolate the sample points can reduce the amount of calculation in solving control points for the curve. The effects to fitting process of using different sampling methods are studied and an algorithm to select sample points in segmented parts is designed.

Path optimization simulations and machining tests carried out on a vertical machining center show that the proposed approach improves the efficiency of machining and the surface quality.

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Keywords: NC Machining, Path Optimization, NURBS, Sample Points