高速主轴用串接复合滚动轴承的试制

1 前言机床主轴高速化的历史相当久远,目的是为提高生产率和改善加工特性。近年,为开发陶瓷等新材料的加工及研磨,对机床高速化有更高要求。

基于EMD与ICA的滚动轴承复合故障诊断

针对单通道情况下滚动轴承复合故障难以分离问题,提出基于经验模式分解(empirical mode decomposition,EMD)的独立分量分析(independent component analysis,ICA)算法.该方法首先对单通道采集的轴承复合故障信号进行EMD分解,得到多个基本模式分量函数(intrinsic mode function,IMF),然后依据帩度指标及相关系数值,选取有效的IMF分量与原观测信号组成新的观测信号,对其进行ICA处理,进而实现轴承复合故障的分离.实验结果表明,该方法可有效地分离轴承早期的复合故障.

基于最大相关峭度解卷积的滚动轴承复合故障诊断方法

受环境噪声、传递路径、信号衰减以及源信号本身比较微弱的影响,滚动轴承早期微弱冲击性故障的信号特征难以提取。近年来,最小熵解卷积(Minimum Entropy Deconvolution,MED)已经成功应用在旋转机械故障检测中来提取振动冲击。MED方法的提取过程是一个迭代选择的过程,通过迭代选择一个有限脉冲响应使信号的熵最小,从而对信号进行滤波。但是该方法有一定的局限性:其对于单一冲击的信号解卷积效果良好,但是处理具有强噪声或者多个冲击源共同作用时的信号很困难。为了解决这个问题,提出新的解卷积方法:最大相关峭度解卷积(Maximum Correlated Kurtosis Deconvolution,MCKD),可有效利用滚动轴承故障周期性冲击的特点,其与MED相比,克服了单一冲击的限制,对两种冲击源甚至是多种共同卷积的解卷积具有更好的特征提取效果。仿真和实验对比验证了该方法具有良好的降噪和故障特征增强效果。

基于IVMD的单通道盲源分离方法及其应用

针对机械振动信号单通道盲源分离问题,提出了一种融合改进变分模态分解与时频分析的单通道信号盲源分离方法,并将其应用于滚动轴承复合故障的诊断中。该方法首先针对变分模态分解(Variational Mode Decomposition)过程中的层数选取问题,提出了一种根据谱相关系数确定分解层数的改进变分模态分解方法(Improved Variational Mode Decomposition,IVMD)。其次,采用改进变分模态分解对观测的单通道机械振动信号进行处理,得到一系列有限带宽固有模态函数(Band-limited Intrinsic Mode Functions,BLIMFs);然后,将原信号与得到的固有模态分量及其残余项组成虚拟多维观测信号,以突破传统盲源分离方法要求传感器数目必须大于或等于分离出的分量数目限制,并利用奇异值分解估计振源的数目。最后,根据振源数目选择与原信号谱相关系数较大的BLIMFs分量,并将分解残余项作为单独分量,重组虚拟多通道观测信号。采用基于时频分析的盲源分离算法实现非平稳信号的盲源分离;仿真和实验结果表明,该方法能够有效提高非平稳振动信号的分离精度,实现滚动轴承复合故障的诊断。

Bending stress of rolling element in elastic composite cylindrical roller bearing

A new structure design method of elastic composite cylindrical roller bearing is proposed, in which PTFE is embedded into a hollow cylindrical rolling element, according to the principle of creative combinations and through innovation research on cylindrical roller bearing structure. In order to systematically investigate the inner wall bending stress of the rolling element in elastic composite cylindrical roller bearing, finite element analysis on different elastic composite cylindrical rolling elements was conducted. The results show that, the bending stress of the elastic composite cylindrical rolling increases along with the increase of hollowness with the same filling material. The bending stress of the elastic composite cylindrical rolling element decreases along with the increase of the elasticity modulus of the material under the same physical dimension. Under the same load, on hollow cylindrical rolling element, the maximum bending tensile stress values of the elastic composite cylindrical rolling element after material filling at 0° and 180° are 8.2% and 9.5%, respectively, lower than those of the deep cavity hollow cylindrical rolling element. In addition, the maximum bending-compressive stress value at 90° is decreased by 6.1%.