高速超高速磨削工艺及其实现技术

高速超高速磨削加工是先进制造方法的重要组成部分，集粗精加工与一身，达到可与车、铣和刨削等切削加工方法相媲美的金属磨除率，而且能实现对难磨材料的高性能加工。本文主要论述了高速超高速磨削工艺技术的特点；分析了电主轴是高速超高速磨削主轴系统的理想结构，介绍了陶瓷滚动轴承、磁浮轴承、空气静压轴承和液体动静压轴承在主轴单元中的应用；超高速砂轮主要用电镀或涂层超硬磨料(CBN、金刚石)制成，介绍了超硬磨粒的特点和砂轮的修整，分析了在高速及超高速磨床上得到广泛应用的德国Hofinann公司生产的砂轮液体式自动平衡装置；介绍了高压喷射法，空气挡板辅助截断气流法，气体内冷却法，径向射流冲击强化换热法磨削液供给系统的特点；最后介绍了直线电机进给系统和声发射智能监测系统等实现高速超高速磨削的关键技术。     

磁浮主轴回转精度的测试

磁浮主轴与一般主轴相比,其转速高,某些特殊用途的磁浮主轴还必须具有极高的回转精度。本文针对磁浮主轴的特点,以复数型频率分析的回转精度的理论为基础,设计了五自由度磁浮主轴回转精度的测试系统。硬件电路采用了锁相倍频技术,采集的数据用复序列FFT进行处理,达到了检测目的。     

高速切削机床中的磁轴承

高效化是机械制造的永恒主题之一。本文简介了高速切削的理论依据及其优点，分析了磁悬浮轴承的原理、特点以及磁浮轴承在高速切削机床上的应用情况，从而说明了磁浮轴是高速切削机床最理想的轴承之一。     

NTN为机床主轴承而设计的新产品

用于机床主轴的ULTAGE超高速精度轴承系列是NTN新的滚动轴承系列，它针对机床的特别要求：高效的加工操作，高度的可靠性，高质量的加工过程及环保的操作，而特别设计的。     

磁浮轴承轴向解耦

磁浮轴承机械 ，由于径向位移传感器与电磁轴承之间轴向偏置一定距离，径向位移传感器信号不能直接与与反馈控制，因此本文提出磁浮主 一径向两位移传器信号间具有耦合关系。论文通过磁浮系统仿真及回转精度实验，分析了径向位移传感器售间轴向解耦对主稳态精度的影响。     

磁浮轴承气隙中磁场强度静动特性测试

金属软磁材料在交变电流作用下被磁化，具有磁滞及磁饱和特性。本文分析了金属软磁材料的非线性磁化特性的滞后及磁滞损耗；偏置磁场对系统刚度的影响。提出了磁浮轴承气隙中磁场强度静、动特性的实验测试方法，为磁浮轴承系统设计及非线性控制的研究提供了理论基础。     

基于STM32F407VE的磁浮轴承控制器的设计

为了对传统磁浮轴承控制器的不足之处进行改进，设计了一种基于ARM的磁浮轴承控制器。该控制器能够控制5个维度使转子悬浮，同时能够及时调整10组电流驱动器。该控制器选用32位ARM STM32F407VE作为核心处理芯片，具有可靠性高，速度快的优点，精度能够达到0.02 mm，运行稳定可靠。     

高速主轴的轴承技术

主要介绍用于高速主轴的轴承技术，叙述了三种常用的高速主轴轴承的结构优化、性能特点，以及为使得这些轴承适应高速运转所需解决的问题。     

高速机床主轴－轴承系统动态性能研究

为研究主轴－轴承系统的动态性能,以某型号精密卧式加工中心主轴系统为研究对象,通过偏心质量激励法测得主轴支承轴承刚度,采用Timoshenko梁单元对主轴进行有限元建模,系统地分析了主轴离心效应、轴承预紧力对于主轴动态性能的影响,并进行了实验验证。结果表明：提高预紧力可有效增加主轴轴承刚度,提高主轴动态性能。同时证明采用有限元法计算主轴轴承的刚度是一种行之有效的方法。     

落地铣镗床主轴系统优化研究

建立了落地铣镗床主轴系统的模型,研究主轴径向变形;对落地铣镗床主轴轴承寿命、主轴大齿轮对轴承刚度和主轴变形的影响进行分析,并对轴承配置进行了优化分析,为轴承组合方式的选用以及大齿轮支承的合理配置提供了依据。     

高速电主轴单元的热-结构性能虚拟仿真分析

主轴单元的热变形是高速加工中影响精度的主要因素。本文利用大型有限元分析软件ANSYS对高速电主轴进行了热-结构耦合分析。计算结果显示，设计的高速电主轴单元主轴轴承、主轴前端温升理想，工作端轴向热位移很小。这表明设计的电主轴具有良好的热-结构性能，可以满足加工精度要求。     

高速电主轴辐射噪声特性分析

研究了3种电主轴的辐射噪声特性。通过实验测量了电主轴辐射噪声,分析了全陶瓷轴承电主轴、钢轴承电主轴和无内圈式陶瓷轴电主轴辐射噪声的时频特性。实验结果表明:提高旋转速度,全陶瓷轴承电主轴与钢轴承电主轴辐射噪声均呈增大趋势,且辐射噪声中含有旋转频率和2倍转频特征,而无内圈式陶瓷轴电主轴的辐射噪声呈现波动式变化,其声压级高于其他2种电主轴,且频谱较为杂乱;在高转速时全陶瓷轴承电主轴声波具有明显的周期性;3种电主轴辐射噪声中均具有较高的摩擦与冲击噪声。     

An elastic deformation model of high speed spindles built into ball bearings

Kinematic characteristics and elastic deformation properties of ball bearings such as stiffness, axial, and radial deflections of the rings, speeds of balls, contact angles, and loads, all vary strongly with rotational speed, temperature, and axial preload. This paper presents an elastic deformation model of spindle units built into ball bearings, which are running on high rotational speed and axial preload. For this, software for simulation of the high speed spindle units was developed and introduced into a practical use. A computer aided analysis of the model was carried out and experiments were made, which showed a significant effect of high rotational speed, cutting load, bearing axial preload, and a new effect for which the criteria for a choice of bearing preload are given.     

Error correction in hydrostatic spindles by optimal bearing tuning

In this paper a high precision grinding wheel is considered as a rigid rotor mounted on two hydrostatic bearings. The equations for small perturbations of the wheel on the bearings are derived in the form of a multi-input, multi-output transfer function matrix, enabling the frequency response function of the wheel to be determined. Thereafter an optimisation algorithm is proposed which considers speed, load and dimensions of the spindle, and computes optimal stiffness and damping of the bearings. The dynamic characteristics of the bearings, tuned for minimum radial displacement of the spindle, is achieved maximising thereby the accuracy of the grinding process. Simulation results show that by stiffness coarse adjustment, and fine adjustment of the damping in the bearings, a spindle with 35 μm manufacturing error, can produce components with 3 μm accuracy.     

定向装配法在精密主轴装配中的应用

定向装配法是提高精密机床主轴装配精度的有效方法之一.分析了装配过程中主轴前后轴承误差对机床主轴精度的影响,介绍了定向装配方法的原理及实现方法,将这一方法运用在某高精度主轴装配中,取得了较好的效果.     

Virtual Design and Optimization of Machine Tool Spindles

An integrated digital model of spindle, tool holder, tool and cutting process is presented. The spindle is modeled using an in-house developed Finite Element system. The preload on the bearings and the influence of gyroscopic and centrifugal forces from all rotating parts due to speed are considered. The bearing stiffness, mode shapes, Frequency Response Function at any point on the spindle can be predicted. The static and dynamic deflections along the spindle shaft as well as contact forces on the bearings can be predicted with simulated cutting forces before physically building and testing the spindles. The spacing of the bearings are optimized to achieve either maximum dynamics stiffness or maximum chatter free depth of cut at the desired speed region for a given cutter geometry and work-piece material. It is possible to add constraints to model mounting of the spindle on the machine tool, as well as defining local springs and damping elements at any nodal point on the spindle. The model is verified experimentally.     

Digitally controlled output filters for improvement of temperature behavior of machine tool main spindle drives

Variable speed main spindle drives of machine tools are usually fed by three-phase two-level inverters. Because of the switching operating mode of these inverters, the motor voltages and currents contain harmonics which do not contribute to torque formation but solely to an undesirable warming of motor spindle elements. This warming results in thermal elongation of the spindle shaft and therefore to a deviation in dimensional accuracy. The increased wear of the spindle bearings through high temperature differences between the inner and outer rings of the bearings is another drawback. This paper proposes a novel high-performance control system of an interior permanent magnet synchronous motor (IPMSM) using an inverter with an LC output filter. The combination of inverter and filter reduces the motor losses by compensating the switching ripples and therefore leads to an evident improvement of the temperature behavior of the main spindle drive.     

Characterizations and models for the thermal growth of a motorized high speed spindle

In this paper, the characterizing and modeling of the thermal growth of a motorized high speed spindle is reported. A motorized high speed spindle has more complicated dynamic, non-stationary and speed-dependent thermal characteristics than conventional spindles. The centrifugal force and thermal expansion occurring on the bearings and motor rotor change the thermal characteristics of the built-in motor, bearings and assembly joints. It was found that conventional static models using regression analysis and artificial neural network failed to give satisfactory model accuracy and robustness. An auto-regression dynamic thermal error model, that considers the temperature history and spindle-speed information, has been proposed and proved to improve the model accuracy. However, it was found that temperature-based thermal error models, that correlated thermal displacement of the rotating cutting tool to the temperature measurements on the spindle housing, were not robust. Many nonlinear and time-varying thermal sources, such as coolant jacket, motor air gap, motion joints and assembly interfaces influence thermal displacement. The relationship between temperature measurements and thermal displacements is highly nonlinear, time-varying and non-stationary. A new thermal model which correlates the spindle thermal growth to thermal displacements measured at some locations of the rotating spindle shaft has been proposed. It was found that the displacement-based thermal error model has much better accuracy and robustness than the temperature-based model.     

Evaluation of an internally spring preloaded four contact-points bearing for spindle units

In this paper, the concept of an internally spring preloaded four contact-points bearing for the use in high precision and high speed applications is investigated. It is designed as a compact self-contained fixed bearing unit that is free of play, easy to mount and resistant against temperature differences between the inner and outer ring. The concept of the bearing, its functionality and properties are introduced and the results of an experimental analysis of a first prototype are presented. The prototype bearing, which is based on a hybrid 7014 spindle bearing with an additional spring preload unit, was manufactured by hard turning. Its properties are compared to those of similar two and three contact-points spindle bearings. Typical requirements in modern high precision applications, e.g. machine tool spindle units, and limiting characteristics of bearings, such as displacement, stiffness, friction torque and operating temperature, are considered. Finally, the potential of the new bearing concept is discussed.