陶瓷CBN砂轮高速回转试验机关键技术研究

发布时间：2018-01-25 04:25

本文关键词： 陶瓷CBN砂轮回转试验机主轴有限元声发射　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：陶瓷CBN(Cubic Boron Nitride立方氮化硼)砂轮是超硬材料及制品行业最具代表性产品,是磨削加工领域中的一种高性能磨具,具有高速、高效、高精度、低污染等优点。陶瓷CBN砂轮的主要性能检测是回转强度试验,因为砂轮在作业过程中一旦破碎其后果是不可想象的。高速回转试验机应用于回转类砂轮的回转强度试验,从而检验砂轮在规定试验条件下的回转强度。目前我国的超硬材料磨具高速回转试验检测设备还处于相对滞后的状态,主要原因是主轴系统方面有效负载能力低、转速上不去,控制系统方面现有的砂轮破碎识别方法不能满足超硬类砂轮破碎信号识别。本课题在深度分析陶瓷CBN砂轮回转试验基本原理和功能要求的基础上,从机械主轴系统自主设计、砂轮破碎信号检测入手,对陶瓷CBN砂轮高速回转试验机关键技术进行了研究。基于自主设计的主轴系统,本文对主轴轴承选用、安装、轴承刚度进行了深入研究。应用赫兹理论计算出预紧力,采用MATLAB编程软件验证了增大预紧力不仅可以提高轴承的刚度,还能提高主轴的静态刚度和临界转速;得出主轴转速提高会使轴承径向刚度减小、轴向刚度增大,预紧力和轴承刚度存在一个平衡点的结论。采用有限元分析理论,以ANSYS软件为基础,建立了主轴模型,分别对主轴静、动态特性进行了研究,分析了主轴刚度和应力特点,确定了主轴固有频率、主要振型和共振频率,得到了主轴最小动刚度频率、主轴谐响应固有变形量和固有频率特征值,验证了主轴系统结构设计的合理性。为了提高砂轮破碎信号识别的精准性,本文对陶瓷CBN砂轮的破碎特征、振动机理、信号特点进行了深入研究,结合声发射信号原理、特点、处理方法,以普通砂轮声发射特征为基础,得到了砂轮破碎具有非高斯信号特征。依据设计的实验方案,通过在自主设计主轴系统上进行陶瓷CBN砂轮回转实验,采用AE信号时域分析方法,研究了砂轮破碎后与破碎前相比声发射信号的电压幅值图、能量图、波形图,结果表明AE信号特征均发生明显变化,得到了AE信号波形由平稳连续信号变成突发式连续信号的结论。运用FFT运算法则、小波变换,验证了AE信号符合Symlet小波函数对称性,得出了陶瓷CBN砂轮破碎后AE信号向高频区发展的变化特征,表明陶瓷CBN砂轮破碎后会产生一个高频电压信号的结论。研究结果表明:自主设计的主轴系统稳定性达到预期效果;声发射技术优于目前常用的光电法、音量法和振动法,更适合用于砂轮回转试验破碎识别领域。
[Abstract]:Ceramic CBN(Cubic Boron Nitride cubic boron nitride (CBN) grinding wheel is the most representative product of superhard materials and products industry, and it is a kind of high performance abrasive tool in grinding field. It has the advantages of high speed, high efficiency, high precision and low pollution. The main performance test of ceramic CBN grinding wheel is rotary strength test. It is unthinkable that the grinding wheel is broken once it is broken in the process of operation. The high-speed rotary testing machine is applied to the rotary strength test of the rotary grinding wheel. In order to test the rotational strength of the grinding wheel under the specified test conditions, at present, the high speed rotary testing equipment of the super hard material grinding tools in our country is still in the state of relative lag. The main reason is the low payload capacity of the spindle system, the speed of the system does not go. The existing grinding wheel breaking identification methods in control system can not meet the breaking signal recognition of superhard grinding wheel. This topic is based on the in-depth analysis of the basic principle and functional requirements of ceramic CBN wheel rotary test. Starting with the independent design of the mechanical spindle system and the detection of the grinding wheel breaking signal, the key technology of the ceramic CBN grinding wheel high-speed rotary testing machine is studied. Based on the self-designed spindle system, the spindle bearing is selected in this paper. The stiffness of bearing is studied deeply, the preload is calculated by Hertz theory, and the MATLAB software is used to verify that increasing preload can not only improve the stiffness of bearing. It can also improve the static stiffness and critical speed of the spindle. It is concluded that the increase of spindle speed will decrease the radial stiffness and increase the axial stiffness of bearing, and there is a balance point between preload force and bearing stiffness. The theory of finite element analysis is adopted and based on ANSYS software. The static and dynamic characteristics of the spindle are studied, the stiffness and stress characteristics of the spindle are analyzed, and the natural frequency, main mode and resonance frequency of the spindle are determined. The minimum dynamic stiffness frequency of the spindle, the intrinsic deformation of the spindle harmonic response and the eigenvalue of the natural frequency are obtained, which verifies the rationality of the structural design of the spindle system, in order to improve the accuracy of the grinding wheel breaking signal recognition. In this paper, the crushing characteristics, vibration mechanism and signal characteristics of ceramic CBN grinding wheel are studied in depth. Combined with the acoustic emission signal principle, characteristics, processing methods, based on the ordinary grinding wheel acoustic emission characteristics as the basis. According to the designed experimental scheme, the rotary experiment of ceramic CBN grinding wheel was carried out on the self-designed spindle system, and the time-domain analysis method of AE signal was adopted. The voltage amplitude diagram, energy diagram and waveform diagram of acoustic emission signal after grinding wheel breaking are studied. The results show that the characteristics of AE signal are obviously changed. The conclusion that AE signal waveform changes from stationary continuous signal to burst continuous signal is obtained. The FFT algorithm and wavelet transform are used to verify that AE signal conforms to the symmetry of Symlet wavelet function. The characteristics of AE signal development to high frequency region after crushing ceramic CBN grinding wheel were obtained. The results show that the ceramic CBN grinding wheel will produce a high frequency voltage signal after crushing. The results show that the stability of the self-designed spindle system achieves the desired effect. The acoustic emission technique is better than the photoelectric method, volume method and vibration method, and is more suitable for grinding wheel rotary test crushing identification.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG743;TH873

【相似文献】