Grinding Chatter Detection and Identification Based on BEMD and LSSVM

Huan-Guo Chen,Yong-Yu Yi,Jia-Cheng Qian,Jian-Yang Shen,Wen-Hua Chen,Chun-Shao Huang

doi:10.1186/s10033-018-0313-7

Abstract

Grinding chatter is a self-induced vibration which is unfavorable to precision machining processes. This paper proposes a forecasting method for grinding state identification based on bivarition empirical mode decomposition (BEMD) and least squares support vector machine (LSSVM), which allows the monitoring of grinding chatter over time. BEMD is a promising technique in signal processing research which involves the decomposition of two-dimensional signals into a series of bivarition intrinsic mode functions (BIMFs). BEMD and the extraction criterion of its true BIMFs are investigated by processing a complex-value simulation chatter signal. Then the feature vectors which are employed as an amplification for the chatter premonition are discussed. Furthermore, the methodology is tested and validated by experimental data collected from a CNC guideway grinder KD4020X16 in Hangzhou Hangji Machine Tool Co., Ltd. The results illustrate that the BEMD is a superior method in terms of processing non-stationary and nonlinear signals. Meanwhile, the peak to peak, real-time standard deviation and instantaneous energy are proven to be effective feature vectors which reflect the different grinding states. Finally, a LSSVM model is established for grinding status classification based on feature vectors, giving a prediction accuracy rate of 96%.

Highlights

Grinding is an abrasive machining process which is widely used in modern manufacturing practice to produce high surface quality and close tolerance [1,2,3,4]
The extraction criterion of true bivarition intrinsic mode functions (BIMFs) based on the correlation coefficient successfully distinguished the true BIMFs from the spurious components
Phase shifting of the BIMFs were calculated, as well as the peak to peak, standard deviation, and instantaneous energy being presented as chatter feature vectors for detecting different vibration states of grinding

Summary

Introduction

Grinding is an abrasive machining process which is widely used in modern manufacturing practice to produce high surface quality and close tolerance [1,2,3,4]. With the increasing mature of ultra-high speed grinding, its advantages are further improved, that providing convenient conditions for development of aerospace technology, transportation, military and other industries [5, 6]. Grinding chatter has negative impacts on the ultimate geometrical workpiece accuracy, surface quality and productivity of machinery. It leads to increased wheel wear and adds time and costs to manufacturing [7, 8].

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