基于声发射技术的砂轮磨损实验研究

Experimental Study of Grinding Wheel Wear Process Based on Acoustic Emission Technology

砂轮磨损状态复杂多变,磨损信号干扰多,特征提取困难。文章针对砂轮磨损过程,提出一种基于声发射技术的砂轮磨损表征方法。利用小波能量分析对磨削过程声发射RMS(均方根)信号进行重构与消噪,研究声发射RMS(均方根)信号频谱矩心这一特征值与工件表面粗糙度的对应关系。得出砂轮修整初期频谱矩心低,砂轮磨损后频谱矩心显著增大,由于磨粒自锐作用,频谱矩心会呈现周期性变化规律;在同一周期内,处于低频段的砂轮磨削出的工件表面粗糙度必优于处于高频段的砂轮;在不同周期内砂轮磨削出的工件表面粗糙度不具有可比性;表明了磨粒自锐的随机性。而且随着砂轮磨损的增加,频谱矩心高频段持续时间越来越长,直至砂轮剧烈磨损。

Grinding Wheel wear is complex,there is much interference signal and it is difficult to extract features. This paper aimed at providing a suitable characterization method based on acoustic emission technology to showthe process of the grinding wheel wear. Using the method of wavelet energy analysis and noise elimination to deal with the acousitc emission RMS signal,acquiring the relationship between surface roughness of workpiece and spectral centroid. It is found that the spectral centroid of the acousitc emission RMS signal is lowat the beginning of the dressing,and the spectrum centroid is obviously increased after the grinding wheeel wear. Because of the abrasive self-sharpening effect,the spectrum centroid will decrease from high frequency to lowfrequency,Showing a periodic variation. During the same period,when the spectrum centroid is low,the surface roughness of workpiece is better,and the surface roughness of workpiece in different period is not comparable,which indicates the randomness of self-sharpening of abrasive grains. And with the increase of abrasive wear,the duration of the high-frequency is longer and longer,until the abrasive wheel wear is severe.