HSK刀柄不平衡引起振动信号的特征分析

介绍了不平衡振动的机理;分析了HSK刀柄产生不平衡的原因和振动信号的特征;阐述了信号预处理的方法;最后利用小波理论进行小波变换重构信号,更准确的提取了HSK刀柄的振动信号,为今后的科学研究和HSK综合测量系统的开发提供了很好的依据。     

BT与HSK工具系统高速加工性能比较分析

通过对BT工具系统和HSK工具系统的结构特点和数字模拟分析比较,从理论上论证了HSK工具系统的高速加工性能优于BT工具系统,并通过实验比较了两者的静、动态性能.     

叶片安装误差引起的不平衡质量对风力机塔架振动的影响

利用ANSYS建立了塔架的柔性体模型,并对其进行了模态分析,同时在考虑叶片安装误差引起的不平衡质量的基础上,利用ADAMS建立了把塔架作为柔性体的风力发电机系统的柔性体模型,研究了风速变化和变桨引起的风力发电机塔架上方各部件重心的变化对塔架振动的影响,得到了基于上述因素综合作用下的振动分析和动载荷分析结果,为塔架的优化设计提供了更准确的依据.     

HSK空心短锥柄的结构特点及其应用

HSK空心短锥柄适用于超高速加工,与7～24锥柄相比有明显的优越性。本文介绍了HSK空心短锥柄的结构特点、工作原理、制造和使用应该注意的一些问题。     

流体振源引起石油化工管线振动的分析

以某炼油厂的一条加氢管线振动为例，对管线中流体振源引起的振动问题从现场测试和数值计算等方面进行了分析和研究，提出了一套用于减轻石油化工管线振动的分析方法。     

电梯导靴引起的振动

本文对电梯运行时导靴的非线性摩擦影响进行了数学模型分析，提出了抑制自激振动的各种措施，同时将结果推广于自动扶梯扶手带的蠕动运行和对电梯平层的影响，文中对导靴引起的瞬态振动也进行了适当的说明。     

基于MUSIC算法的动不平衡信号提取方法研究

针对相关滤波等经典频域分析方法提取动不平衡信号时,近频干扰抑制能力及参数估计精度严重依赖数据长度的问题,提出了一种基于残差MUSIC(multiple signal classification)谱分析的正弦参数估计方法,以残差MISIC谱中给定频率点的幅度值为观测变量判定参数拟合效果,提取该频率成分的幅值和相位。实验表明此方法与相关滤波法相比具有更高的频率分辨率,对抑制近频干扰的能力更出色,较好地解决了提高动不平衡信号提取精度与提高动平衡试验效率难于两全的问题。     

Improvement of the vibration performance of rod-fastened rotor by multioptimization on the distribution of original bending and unbalance

Manufacturing errors of disks, namely, parallelism error and mass imbalance, cause complex bending and unbalance of rod-fastened rotor (RFR) after assembly, which act as original excitations and increase vibration. A method was introduced in this study to improve the vibration performance of an RFR. The method optimized the distribution of bending and unbalance and offered an improved assembly scheme. As a basic step, the quantitative relation of RFR bending and assembly angles of disks with parallelism errors was established. On this basis, dimensionless bending was proposed to evaluate the integral bending of an RFR. With respect to the unbalance of the RFR, the balance principle of rigid rotor was applied, that is, small equivalent reaction forces were considered better. The dynamic model of an RFR supported by elliptic bearings was established by using finite element method. Optimizations on the bending and unbalance were then performed individually, and related vibration responses of the RFR system were investigated. Results of single optimization on bending and unbalance proved the effectiveness in reducing the vibration responses of the RFR system. Moreover, results revealed that the bending and unbalance induced mainly the vibration of first order, which explained the difficulty to distinguish each other in actual balance of an RFR. Finally, the multioptimization on the bending and unbalance was performed, which greatly decreased the vibration responses of the RFR system. Optimizations on bending and unbalance in this study were independent with supporting conditions, which gave them a better application and provided a new way to improve the dynamic performance before assembly.

     

半球谐振子质量不平衡对振动特性的影响研究

质量不平衡是半球谐振子制造过程产生的主要缺陷之一,其对谐振子的振动特性产生重要的影响。为制定半球谐振质量不平衡评价方法及为修调提供依据,对谐振子的结构特征及质量不平衡进行了表征,通过耦合振动物理模型及仿真分析,明确了谐振子耦合振动产生机理、质量不平衡对频率裂解及支撑损耗的影响。并通过实验,测得了谐振子的不同去除质量下频率裂解特性及耦合振动特性,得到了谐振子质量不平衡与振动特性之间的关系,通过实验数据得出未经过平衡的谐振子1、3次谐波及2次谐波的分布特征,以及它们引入的支撑损耗分别为1.6×10^-8、3.7×10^-9;频率裂解与4次谐波不平衡质量对应关系为0.01 Hz/μg,由此可以对谐振子质量不平衡进行评价及制定调平工艺。     

主被动磁悬浮转子的不平衡振动自适应控制

针对主被动磁悬浮控制力矩陀螺转子高速旋转时产生的不平衡振动,提出了基于滑模观测器和陷波器的主被动磁悬浮转子不平衡振动自适应控制方法。该方法采用滑模观测器使同频振动的控制不受磁轴承的刚度参数摄动和磁力耦合的影响,将滑模观测器与陷波器结合,无需区分电流刚度力和位移刚度力,无需设计算法补偿功率放大器的影响,可自适应消除不平衡振动。对该方法进行了仿真和实验验证。仿真结果显示该方法可使同频轴承力大幅减小;实验结果显示,虽然主被动磁悬浮转子的被动轴承不可控,同频振动仍由0.053g减小为0.012g,减小了77%。得到的结果表明,该方法不仅适用于主被动磁悬浮转子,也适用于全主动磁悬浮转子。     

基于最小二乘法的转子不平衡振动信号的提取

不平衡振动是旋转机械失效的重要原因,实现精确平衡必须从强噪声中提取出与主轴转速同频的不平衡量振动信号,因此,不平衡振动信号的准确提取是进行转子动平衡的前提。基于最小二乘法的原理,通过建立提取转子振动不平衡信号的数学模型,提出了一种准确提取转子不平衡振动信号的方法。基于该方法,并通过Matlab仿真分析,有效提取了转子振动不平衡信号。研究表明,基于最小二乘法的转子振动不平衡信号提取方法能够准确提取转子不平衡振动的幅值和相位信息,该方法可用于转子不平衡振动监测及动平衡等方面。     

Testing a pump unit by identification measurements of vibration signals

A procedure that operates using the theory of identification measurements of signals and a computerized vibration-monitoring device for an NM 12500-210 pump unit are described. It is shown that the state of an object that is being monitored can be represented by a cluster, an array of linguistic characteristics of model signals with known distribution laws of instantaneous values. A consecutivecomparison procedure is described for assessing the condition of each element in the cluster and of all the clusters that contain respective elements that are stored in a database.     

Adaptive modelling of transient vibration signals

Conventional vibration signal processing techniques are most suitable for stationary processes. However, most mechanical faults in machinery reveal themselves through transient events in vibration signals. Time-series modelling, including autoregressive moving average (ARMA) modelling and autoregressive (AR) modelling, is an efficient approach for transient signal analysis. Based on the adaptive prediction technique, this paper applies the principle of the adaptive line enhancer (ALE) to the modelling of transient vibration signals. The time-series models, adaptive algorithms and the rational time–frequency transfer function are investigated in the paper. Simulation and experimental studies with different time–frequency–amplitude distributions and transient vibration responses are described. The results show that the adaptive modelling method can trace the time–frequency signal and extract dynamic features such as time–frequency distributions and time–amplitude distributions from sample signals. Given the simple programming and potentially easy implementation in on-line applications, this method should have application in machine monitoring and fault diagnosis.     

汽轮机叶片问题引发的异常振动故障诊断

从一台300MW机组的轴系异常振动诊断入手,研究了该型机组更换叶片后低压转子的振动特点和处理方法.其现场动平衡方法为解决该型机组轴系振动故障问题提供了有效和借鉴.     

3D spectral analysis for vibration signals by wavelet-based demodulation

In this paper, a wavelet-based demodulating function is proposed to apply in 3D spectral analysis for vibration signals. In the function, there are three parameters required to assign for adjustment and designation of the filtering passband, which are the low cut-off frequency, the high cut-off frequency and the dilation. Accordingly, it would be convenient to apply in the high-frequency resonance technique. In addition, by sweeping the filtering passband from a low-frequency band to a high-frequency band, a 3D spectrum could be constructed to describe how energy distribution between the instantaneous frequency and the filtering passband for a vibration signal. The 3D spectrum would be helpful to give a clear view of both characteristic frequencies and system resonances, and possesses the advantage of minimising the interventions by the end-user.     

铣削过程中振动信号的关联维特征

采用关联维数定量刻画铣削过程中的不同工作状态的振动特征,估计出已加工表面的粗糙度.在计算关联维数中,对选择嵌入维数和延迟时间提出了一种改进的G-P算法,求解出在不同主轴转速、不同进给速度、不同切削深度的切削用量下铣削振动信号的关联维数.研究表明:在不同切削状态下,工件的振动信号的关联维数不同;且随着工件振动信号关联维数的增加,加工表面粗糙度也随之增加.因此,关联维数可以作为识别已加工表面粗糙度的特征量.     

Cyclostationary modelling of rotating machine vibration signals

This paper is dedicated to modelling rotating machine signals as cyclostationary processes, with strong emphasis on the peculiarities and pitfalls that this issue implies. The objective is to demonstrate that machine signals require specific processing that are much more subtle than for communication signals—from which the paradigm of cyclostationarity was originally issued from and developed for. First, different types of cyclostationarity embracing a multitude of rotating machine signals are distinguished. In particular, the importance of considering pure rather than impure cyclostationarity is stressed out. Next, the relationships between angle and time cyclostationarity are investigated and some useful results are derived. It is shown that vibration signals exhibit cyclostationarity if and only if the random speed fluctuation of the machine is periodic, stationary or cyclostationary. Finally, a comprehensive methodology is proposed for processing actual cyclostationary signals: three typical examples dealing with vibration signals of an IC engine, a gearbox and a rolling element bearing are presented, each of them being characterised by a different type of cyclostationarity. The methodology proposed in this paper is general enough and may serve as a guideline for modelling and analysing other types of rotating machine signals, such as pressure signals, electric signals, etc.     

基于胎面扰动的轮胎多边形磨损机理探讨

通过建立基于胎面扰动的非均匀磨损动力学模型,验证了轮胎多边形磨损可以由胎面扰动引起,分析了基于胎面扰动造成轮胎非均匀磨损的机理,得出多边形磨损边数主要由轮胎的转动频率和胎面的固有频率决定的结论,并得到了轮胎磨损边数的计算公式.     

岸边集装箱起重机风振动研究

针对岸边集装箱起重机(简称岸桥)的结构特点及其工作环境的特殊性，采用Wilson-θ法推导了脉动风压作用下结构的动力响应计算公式，通过编制风振计算分析程序，对实际的岸桥进行风振计算机仿真。