一种数控加工二维轮廓的平滑处理技术

Smoothing technique for 2D contour in numerical control plasma cutting

针对由步进电机控制的等离子切割机,为解决速度急剧变化对机床的冲击导致运动不平稳的问题,提出一种对二维轮廓进行平滑处理的方法。基于抛物线弦高误差法、劣弧角度判断法、长度比较法等进行特征点提取,准确识别出轮廓上的尖点、切点、敏感点及可拟合点;根据特征点的不同类型,将轮廓划分为一系列待拟合区间;应用一种优化的双圆弧拟合算法,对待拟合区间进行平滑处理,实现加工轮廓的G1连续,并消除敏感点对加工平稳性的负影响。实验结果表明,应用本算法处理二维轮廓,在保形不走样和保证加工精度的前提下,解决了加工运动平稳性问题,提高了零件加工效率和质量。

In Numerical Control（NC） plasma cutting machine controlled by the step motor,to solve the problem of shock to the machine tool caused by speed＇s dramatic velocity change which could lead to instability in motion,a smoothing technique for 2D contour used in computer aided manufacturing was proposed.Based on the methods of parabolic fitting chord error,judgment of inferior arc angle and comparison of line length,the feature points were extracted,as well as the sharp points,tangential points,sensitive points and fitted points were precisely identified.According to the different types of the feature points,the contour was divided into a series of fitting ranges.To remain G1 continuity of the processed contour and remove the negative impact of sensitive points to smooth motion,an optimal biarc fitting algorithm was applied to process the fitting ranges.The experimental results indicated that the proposed method solved the problem of smooth motion and improved the machining efficiency and part quality on the premise of ensuring contour shape and cutting precision.