滚动轴承故障诊断中精确转频的实用计算新方法

从滚动轴承故障特征频率的计算公式出发,分析了转轴的旋转频率在滚动轴承故障诊断中的重要性;阐述了由变频器频率估算的转频远远不能满足精度要求;提出基于时标脉冲信号的转频的计算方法,给出它的时域计算公式和频域计算公式,并推导出它们各自的适用条件;进一步建立隶属度函数和贴近度函数,以模糊数学为基本原理使用择近原则对转频进行精确调节,弥补了数据点数记录过程中可能存在的误差,消除了频率分辨率的影响,为以后的故障诊断工作做好充分的准备。     

A matrix for the solution of mixed rotating and non-rotating vibration systems

A method is presented based on matrix algebra for the dynamic analysis of a mixed rotating and non-rotating vibration system. Such systems occur in practice when turbo-alternator sets are mounted on flexible steel foundations. The mathematical model considered consists of a rotating non-uniform, bi-symmetric shaft connected via three or more flexible-film bearings to a flexible structure throughout which mass is distributed. The shaft, which is assumed to rotate at constant speed, is heavy, flexible and carries several rigid axi-symmetric discs. Viscous damping is assumed to act in all parts of the system and gravitational effects are ignored.     

A capacitor-based device for the measurement of shaft torque

This paper describes a capacitor technique for the measurement of torque in a rotating shaft. The passive rotating part incorporates a capacitor bridge which is connected capacitively to the static part. This device is simple in operation and is relatively easy to manufacture     

The thyristor commutatorless motor

The commutatorless motor (CLM) is a type of a dc motor whose commutator is replaced by the thyristor power converter. The thyristors are switched by the signals from a position sensor connected to the rotating shaft of the synchronous motor. Therefore, the CLM never loses synchronism and has the good speed characteristics of a dc motor. The current type CLM, having a current smoothing reactor, was studied and found to have better characteristics than the voltage type. In this paper two kinds of the current type CLMs are described; one is the dc CLM using an inverter, the other the ac CLM using a cycloconverter.     

轴系的回旋运动对船舶噪声的影响

船舶的螺旋桨和推进轴组成的轴系在航行时将产生回旋运动。当回旋运动的角频率与轴系的弯曲振动的固有频率吻合时，能产生高能量的噪声辐射。依据工程实例阐述并证实了这一现象。最后，据此对船舶轴系的设计提出一些参考建议。     

变截面功能梯度旋转轴的自由振动特性

基于微分求积有限元(DQFEM)和铁木辛柯梁理论研究轴向变截面功能梯度旋转轴自由振动特性.首先利用上述理论和方法建立理论分析模型;然后将基于该模型所得的计算结果与已有文献和有限元软件ANSYS进行对比验证,结果表明该模型具有准确性、稳定性和通用性;最后采用上述模型分别研究变截面锥度系数和梯度系数对转轴固有频率和临界转速...     

Increasing the sensitivity and accuracy of an instrument for measuring the torque of a rotating shaft with electromagnetic coupling to a surface acoustic wave sensor

The particular features of the measurement of the torque of a rotating shaft using a surface acoustic wave sensor are considered. An approach to choosing the parameters of a contactless transfer device and a piezoelectric substrate for such a sensor, which enables the measurement accuracy to be increased, is proposed. __________ Translated from Metrologiya, No. 12, pp. 15–25, December, 2007.     

Investigation of Rotor Radial Rotating Error upon AMB System

This paper first suggests the use of the Fourier frequency transmission method of two dimensions function （ 2D FFT） to analyze radial rotating errors that occurred in a rotor. Based on this method a magnetic rotor is measured. The authors point out that the main cause to affect radial rotating accuracy of the rotating shaft at a high speed is the dynamic imbalance of the shaft itself. Finally the feedforward control scheme is suggested to improve the accuracy of the shaft in an active magnetic bearing （ AMB ） system.     

Thrust bearing design for high-speed composite air spindles

The air spindles whose shafts are made of carbon fiber composite are appropriate for high-speed and high-precision machining such as small hole drilling of printed circuit board (PCB) or wafer cutting for manufacturing semiconductors because the carbon fiber composite shaft has low rotational inertia, high damping ratio and high fundamental natural frequency.

The axial load capability and stiffness of air spindles for drilling operation are dependent on thrust bearings that are composed of air supply part mounted on the housing and rotating part mounted on the rotating shaft of spindle.

Since the stresses induced in the rotating part of thrust bearing by centrifugal force are very high at high-speed rotation, the axial stiffness and load capability of an air spindle should be designed considering the stresses induced by the centrifugal force as well as the natural frequency of rotating shaft to avoid the resonant whip vibration of the spindle.

In this work, the air supply part of a thrust air bearing for a high-speed composite air spindle was designed considering its axial stiffness and load capability. The rotating part of the thin thrust bearing was designed through finite element analysis considering the static and dynamic characteristics under axial load and the centrifugal force during high-speed rotation.     

离心泵空化下的转速瞬变特性试验研究

通过安装轴编码器获取了离心泵空化过程的转速瞬变信号,利用时域和频域分析手段进一步探索在不同空化程度下转速瞬变的特点和规律.分析结果表明:当离心泵内刚发生空化时,离心泵的转速变化范围最大,以标准差衡量转速的波动程度也最大,严重空化时转速的波动程度高于未空化时的波动程度;在频域上,试验用离心泵-电机系统的转速的固有频率为2...     

Digital and analog readout systems for fiber-optic strain sensors as applied to the monitoring of roller element bearing systems

A rotating machinery test rig was instrumented with fiber Fabry-Perot interferometer strain sensors for condition monitoring of rolling element bearings. Strain variations produced by ball passes were observed and analyzed in the time and frequency domain. Wavelength division multiplexing was utilized to simultaneously monitor the sensors with analog and digital readout systems--analog for high bandwidth and digital for high dynamic range and the monitoring of multiple sensors. The effects of imbalance on the shaft, changes in rotational speed, effects on the rotor system, and detection of bearing defects were investigated. Frequency peaks observed in the bearing sensor spectra closely matched predicted values. Imbalance and rotational speed tests showed good agreement with expected trends, and bearing defects were successfully detected.     

新型旋转角加速度传感器特性标定系统的研究

针对旋转角加速度传感器的标定问题,构建了一套特性标定系统。首先分析了永磁旋转角加速度传感器的工作原理,并提出了一种基于调频调压电源供电的、异步电动机纯单相运行的、可调频调幅的旋转角加速度脉动源系统;然后采用传统增量式光栅编码器和现场可编程门阵列构建了旋转角加速度测量系统;最后通过比较旋转角加速度传感器的输出电压峰值和测量系统得到的实际旋转角加速度峰值,对传感器输出特性进行了标定,得到传感器输出电压与角加速的特性曲线,线性误差为1.81%。     

Characterisation of the conveying effect of turned radial shaft seal counter-surfaces using a simplified hydrodynamic simulation model

A typical sealing system for rotating shafts consists of the radial shaft sealing ring (RSS), the lubricant and the shaft counter-surface (SCS) of the rotating shaft. The properties of the machined surface of the SCS have an impact on the sealing system. The structural pattern of the SCS influences the lubricant flow along the axial direction. In this paper, a simplified micro scale hydrodynamic simulation model is presented in order to study and determine the axial flow of the lubricant induced by the SCS of the sealing system, isolated from the effects induced by the seal, to allow for a rating of the shaft surface. The influence of the seal was neglected to allow for a simplified simulation. Simulated shaft surfaces corresponding to different machining parameters of machined SCS are used as input. These variants of SCS were created using a kinematic model which simulates an ideal surface machining process of the shaft. A micro scale hydrodynamic simulation model is used to investigate the influence of machining parameters on the lubricant flow along the axial direction across the tribo-contact. From this investigation, the connection between parameters applied for machining of the SCS and conveying effects can be estimated. The simulation model is also validated with experimental results of hard turned shafts of different machining parameters. Differences between manufactured real surfaces and kinematically simulated surfaces are the cause of deviations between the results.

     

光电反射式动态扭矩测试方法研究

针对等直径转轴动态扭矩测试方法计算模型和测量装置复杂以及测试范围受限等问题,提出了一种基于DASP的光电反射式动态扭矩测试方法。建立由光电反射式传感器和DASP系统等组成的动态扭矩测试系统,利用传感器光电脉冲信号的时差和相对转角,来实现动态扭矩测量。实测结果表明,通过调整传感器的位置,就可以实时、精确地实现扭矩的非接触式测量。这种测试方法为转轴的扭矩测试提供了一种新的技术途径。     

基于自适应RBF模糊神经网络的旋转柔性铰接梁的振动控制

由柔性关节连接中心刚体和挠性附件的刚柔耦合系统广泛应用于卫星太阳能帆板、空间机器人等领域中,在调姿或者外部扰动带来振动时,将影响系统的稳定性和指向精度,对带有铰接结构的柔性梁的影响更甚。设计并建立了带有柔性关节（谐波齿轮）的旋转柔性铰接梁实验平台,进行了基于压电传感器测量信号的振动频响特性分析,分别采用PD控制和自适应RBF模糊神经网络控制算法,进行了基于电机驱动的位置设定点弯曲振动的主动控制研究。实验比较结果验证设计的自适应RBF模糊神经网络控制算法能够快速抑制振动。

      

Evaluation of the use of envelope analysis and DWT on AE signals generated from degrading shafts

Vibration analysis is widely used in machinery diagnosis. Wavelet transforms and envelope analysis, which have been implemented in many applications in the condition monitoring of machinery, are applied in the development of a condition monitoring system for early detection of faults generated in several key components of machinery. Early fault detection is a very important factor in condition monitoring and a basic component for the application of condition-based maintenance (CBM) and predictive maintenance (PM). In addition, acoustic emission (AE) sensors have specific characteristics that are highly sensitive to high-frequency and low-energy signals. Therefore, the AE technique has been applied recently in studies on the early detection of failure. In this paper, AE signals caused by crack growth on a rotating shaft were captured through an AE sensor. The AE signatures were pre-processed using the proposed signal processing method, after which power spectrums were generated from the FFT results. In the power spectrum, some peaks from fault frequencies were presented. According to the results, crack growth in rotating machinery can be considered and detected using an AE sensor and the signal processing method.     

The stability behavior of rotating composite shafts under axial compressive loads

This paper studies the stability behavior of a rotating composite shaft subjected to axial compressive loads using finite element method. The laminated composite shaft is modeled as a Timoshenko shaft by applying the equivalent modulus beam theory. Numerical results correlate well with the reported beam models. The critical speed of the thin-walled composite shaft is dependent on the stacking sequency, the length-radius ratio (L/R) and the boundary conditions. In addition, the effects of the rotational speeds and the disk location on the rotating shafts' stability are examined as well. The critical load of the rotating thin-walled composite shaft can be nearly assessed from the conventional buckling formulation.     

Harmonic measurements in superconducting magnets for a high energy accelerator

For the multipole field measurement in superconducting magnets for an accelerator application, a practical method was successfully introduced. The method uses a slow rotating coil assembly with an integator and a shaft encoder connected to a computer system. The accuracy and the quickness of the measurement was sufficient for the mass production test of the Fermilab Energy Doubler magnets.     

The effects of quantization noise and sensor nonideality on digitaldifferentiator-based rate measurement

This paper focuses on the nature of the rate error which arises when a first-order digital differentiator is applied to the output of a uniform quantizer for the purpose of rate estimation. The quantizer input is assumed to be a constant-rate signal which is subject to a uniformly distributed noise source. New formulae are presented for the corresponding rms and spectral error characteristics. The results are applicable to the signal processing of sensor outputs, exemplified by the shaft encoder-based velocity estimation of an almost uniformly rotating mass. Both computer-generated finite data sets and experimental data derived from encoder-based shaft velocity measurements are utilized to verify the theoretical results. The results described are also applicable to a more general class of systems which involve the digital differentiation of quantized, noise-affected signals, such as first-order sigma-delta modulators with nominally constant input     

High Precision Robust Automatic Alignment Method for Rotating Shaft

Rotating Shaft is widely used in various high precision instruments on scientific and industrial metrology. This paper proposes a high precision and robust method to automatically align a rotating shaft perpendicular to the horizontal plane. Firstly, an alignment model consisting of a dual-axis inclinometer and four motors is designed. Then the rotating shaft tilt angle between the practical and the ideal shaft is projected to two orthogonal planes, and generates a rotation angle in each plane. The two rotation angles are calculated by differential measurement method based on the inclinometer outputs, and then the relationship of shaft tilt angle against inclinometer outputs is obtained. According to these two rotation angles, the relative heights of the three supporting points of the platform attached to the rotating shaft are calculated. Employing an angle closed loop strategy; the rotating shaft tilt angle is aligned by three linear stepping motors. Experiment results show an alignment precision of 0.003º is achieved using an inclinometer with the resolution of 0.0005º and a linear stepping motor with the regulation precision of 0.89 μm. The proposed method is suitable for a wide variety of precision machines that require the use of rotating shaft.