主轴轴承预紧力在数控维修中的解决方法研究

介绍了计算轴承预紧力需要考虑的因素,研究了轴承预紧力的计算方法及数控机床主轴轴承预紧的方法,详细阐述了以预紧力为依据的机床主轴预紧的方法。该方法用在机床主轴的安装及维修中,可以成功恢复高转速、高精度机床主轴的精度。     

数控机床轴承预紧对主轴刚度的影响

主轴系统的工作性能,对工件的加工质量和机床生产率均有重要影响,对轴承实行预紧,可提高主轴刚度和主轴旋转精度.文章运用ANSYS软件并结合实测研究了轴承预紧与机床主轴刚度的关系,结果表明:通过增加前端轴承预紧量在一定程度上可以改善主轴弯曲刚度,为设计主轴系统提供了一定的借鉴.     

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。     

轴承预紧对机床主轴刚度的影响

阐明了用有限元法分析计算机床主轴组件刚度的步骤和方法,并对主轴刚度进行计算,讨论不同预紧条件下,轴承刚度对主轴性能的影响;并探讨轴承预紧后,增大预紧量对主轴刚度的影响。结果表明:支承轴承预紧的增大使主轴弯曲刚度增幅最大为22%,而对固有频率的影响不明显。     

轴承预紧力对陶瓷电主轴特性影响分析?

基于170 SD30 SY无内圈陶瓷电主轴转子具有比重轻、耐磨、高弹性模量等优良的综合特性,对不同预紧力载荷下的主轴前端振动位移进行仿真分析;在ANSYS中求解因预紧力在轴承处摩擦产生的温升,并导入整个模型当中,研究整个温度场的分布;对轴承在不同预紧力工况下的使用寿命进行计算分析;依据上述仿真和计算分析,并考虑合理的工况条件下选择合理的预紧力,在该预紧力下进行了振动和温升的实验测量,与仿真进行对比,验证仿真的正确性,从而证明选取预紧力的正确性。     

主轴轴承预紧力的在线测量与控制及其对主轴系统特性的影响(上)

文中讨论了主轴轴承预紧力变化机理及预紧力的定量计算,分析了预紧力对主轴热特性和动力学特性的影响并做了试验验证,在介绍国外预紧力控制和补偿的方法的基础上,重点介绍了作者研制的“测力轴承”和“预紧力控制环”,前者用于预紧力的在线监测,后者用于预紧力的调整,后者由于具有较大的阻尼值,能大大地提高主轴系统的动态刚度和抗振能力,减少主轴系统的热变形,从而提高了主轴系统精度,可有效地实现预紧力的最佳适应控制。本文分两期刊完。     

考虑多影响因素精密机床主轴轴承试验台研制

针对精密机床在不同工况条件下的运转特点,对影响机床主轴轴承精度保持性的原因进行研究,研制了适合作用在不同预紧力、转速、外载荷、安装方式等多种试验条件下的精密机床主轴轴承试验台。介绍了试验台的技术方案和设计参数,绘制了试验台二维、三维模型图,并对试验台轴系、基座等关键零部件进行有限元分析。结果表明,试验台关键零部件均满足设计要求,试验台设计方案合理,能够稳定运行,可以满足多工况下精密机床主轴轴承试验的要求。     

非均匀预紧力对主轴系统回转性能的影响研究

为研究非均匀预紧力对轴承-主轴系统回转性能的影响,通过对轴承-主轴试验台施加可控预紧力,检测主轴轴心回转轨迹,并采用最小二乘圆法评定轴心轨迹,研究不同的转速及工况下轴承的非均匀预紧力对主轴轴心轨迹半径的影响。研究结果表明：即使在空载情况下,轴承外圈不同施力点导致的非均匀预紧会对轴心轨迹产生不同的影响;在径向载荷下,合适的非均匀预紧会逐渐改善主轴的回转性能。     

精密高速磨床主轴支承轴最佳预紧力计算

研究了精密高速磨床主轴－轴承轴系动学力特性,在旋转轴振动理论和高速球轴承刚度理论的基础上,本文提出了一种新的计算精密高速磨床主轴轴在的最佳预紧力算法。     

基于MCGS组态软件下电主轴监控系统应用

文章以高速电主轴监控系统为研究对象,分析了机床电主轴需要监测的几个主要参数、系统主要硬件构成和国产组态软件MGCS的主要功能.通过电主轴专用实验平台采集分析机床主轴的振动信号、转速、电机和前后轴承温度、轴向位移及相关状态参数.经采集系统分析后,可通过指示灯为缺乏主轴、轴承知识的一线工作人员提供判断信息.试验证明:该采集系统能够及时识别机床主轴的状态、发现故障早期征兆,从而可以及时消除故障隐患,避免破坏性事故的发生,为专业技术人员在机床主轴的优化设计、检修等方面提供了坚实的技术基础.     

Effect of bearing support structure on the high-speed spindle bearing compliance

This paper investigates the effect of bearing assembly tolerance on the spindle–bearing compliance. In a high-speed spindle system, the bearing characteristics are significantly influenced by the initial assembly tolerance and the thermal deformation of the bearing support structure. In particular, in the very early stage of spindle operation, spindle–bearings could be under hazardous conditions due to the rapid change of the internal pressure resulting from the thermal deformation or the centrifugal force-oriented deformation. The bearing's internal clearance may be also changed with the operating conditions such as external load, rotational speed and operating cycle time. To determine the initial tolerance and the optimal cooling regimen, a comprehensive dynamic modeling and analysis of the high speed spindle system in terms of bearing pressure, bearing compliance and heat generation is required with consideration to those effects. Furthermore, in order to predict spindle characteristics in operation, all of these parameters should be monitored and recalculated in real time. For this purpose, simple and effective equations have been suggested, representing the bearing stiffness in accordance with the thermal deformation. Moreover, contrast to the former bearing analyses which are mostly based on the Hertzian contact model without considering the radial elastic deformation of the races, this paper presents the analytical and experimental investigations on the bearing compliance with additional consideration to both the elastic deformation of the race and the thermal deformation of the housing in terms of the bearing stiffness. The experimental results show the effectiveness of the proposed equations, which will provide a very simplified calculation of the bearing stiffness in dynamic simulation.     

轴承的可靠性分析方法

轴承在程上就用非常广泛,由于轴承作为易损件需要经常维护和更换.准确的科学地判断轴承的使用寿命, 对工业生产十分重要.文章针对工业生产中轴承出现故障的特点,建立了故障模型和可靠性函数.介绍了用威布尔分布进行分析轴承的疲劳寿命的方法,并实际计算了可靠度在0.95时轴承的使用寿命.解决了轴承在生产时比较重要的寿命问题.用威布尔分析轴承寿命是对轴承可靠性进行科学、准确的数学量化.该分析方法也可以应用到其他工程实践当中去.     

基于Workbench的磨齿机主轴系统动态特性研究

主轴系统是磨齿机的重要组成部分,主轴的动态特性对齿轮的磨削精度与生产效率有着很大的影响。以磨齿机的主轴系统为研究对象,在SolidWorks中建立模型,并通过有限元软件Workbench对其进行模态分析,得出了主轴系统的固有频率和最大偏振量。分析了主轴系统在不同跨距和不同主轴材料弹性模量等条件下对主轴动态特性的影响。结果表明：1023号碳板钢的最大变形量相对较小,可作为主轴材料;模态频率随支承间距的增加而提高;主轴系统的最大变形量随支承间距的增加减小,最佳支承间距为240 mm。     

最不利工况下大型数控机床主轴的强度计算

本文根据某大型数控机床主轴不等截面及主轴工作时轴承支座产生小弹性变形的特征建立主轴计算模型，并以超静定法及强度理论计算及校验最不利工况下机床主轴的强度。本文介绍的计算方法对同类机床主轴的设计、强度及刚度校验具有实际参考价值。     

Milling machine spindle analysis using FEM and non-contact spindle excitation and response measurement

In this paper a method for analysing lateral vibrations in a milling machine spindle is presented including finite-element modelling (FEM), magnetic excitation and inductive displacement measurements of the spindle response. The measurements can be conducted repeatedly without compromising safety procedures regarding human interaction with rotating high speed spindles. The measurements were analysed and compared with the FEM simulations which incorporated a spindle speed sensitive bearing stiffness, a separate mass and stiffness radius and a stiffness radius sensitive shear deformation factor. The effect of the gyroscopic moment and the speed dependent bearing stiffness on the system dynamics were studied for different spindle speeds. Simulated mode shapes were experimentally verified by a scanning laser doppler vibrometer. With increased spindle speed, a substantial change of the eigenfrequencies of the bearing-related eigenmodes was detected both in the simulations and in the measurements. The centrifugal force that acted on the bearing balls resulted in a softening of the bearing stiffness. This softening was shown to be more influential on the system dynamics than the gyroscopic moment of the rotor. The study performed indicates that predictions of high speed milling stability based on 0 rpm tap-test can be inadequate.     

Prediction of thermo-elastic behavior in a spindle–bearing system considering bearing surroundings

This paper presents a simulation method based on system dynamics to establish a comprehensive prediction model for the thermal and mechanical behavior of a spindle–bearing system in consideration of bearing surroundings such as assembly tolerance, geometric dimension, cooling conditions, operating conditions and thermal deformation. By introducing a lumped element into the system, not only mechanical properties but also thermal behaviors can be readily examined and predicted. The most important behavior in the spindle–bearing system is the bearing pressure, which determines the spindle characteristics and friction moment. In this study three different simplified assemblies are investigated. One is the bearing inner race–shaft subassembly that includes a negative assembly clearance, and another is the outer race–housing assembly that includes a positive assembly clearance. The third is the entire system that is composed of a rolling element bearing, an inner race–shaft subassembly and an outer race subassembly. The two subassemblies are coupled by rolling elements in which the frictional moment and heat generation vary with the assembly clearance and thermal deformation of the bearing surroundings. The new method can be applied to spindle cooling as well as the optimal thermal and mechanical design of the spindle–bearing system for various surrounding conditions. Furthermore, on the basis of the proposed model, the effect of steel and ceramic bearing materials on the thermo-elastic behavior of the spindle system was investigated.     

小模数滚齿机用电主轴的设计与研究

小模数数控滚齿机去掉了传动用的齿轮副、蜗轮蜗杆副等传动元件,刀具轴和工件轴直接与电机轴相联。几何误差和热误差是小模数滚齿机的主要误差来源,为此,设计了一种新型的电主轴。该电主轴采用了主轴电机置于主轴后轴承之后的形式,缩小了主轴轴承位置的径向尺寸,使轴承摩擦产生的热量的散发,减少了电机发热对轴承变形产生的影响;主轴轴承采用了静压轴承的形式,提高了主轴轴承的耐磨性和回转精度。该电主轴的设计能够提高小模数滚齿机的生产效率和加工精度。     

Analysis of bearing configuration effects on high speed spindles using an integrated dynamic thermo-mechanical spindle model

This work presents the effects of bearing configuration on the thermo-dynamic behavior of high speed spindles using the comprehensive dynamic thermo-mechanical model. The dynamic thermo-mechanical model consists of a comprehensive bearing dynamic model, a shaft dynamic model and a thermal model. The thermal model is coupled with the spindle dynamic model through bearing heat generation and thermal expansion of the whole system based on the bearing configuration. Thus the entire model becomes a comprehensive dynamic thermo-mechanical model. The new thermo-mechanical model also considers a pertinent mapping between bearing stiffness and shaft stiffness matrices based on bearing configurations, so that more general cases of bearing configurations can be modeled. Based on this model, the effects of bearing orientation on the spindle dynamics are systematically described and experimentally validated. It is shown that bearing orientation has a significant effect on spindle stiffness. Finally, the effects of various bearing configurations on spindle thermal and dynamic behavior are illustrated through numerical analysis with three different spindles.     

Modelling of angular contact ball bearings and axial displacements for high-speed spindles

This paper presents modelling of moving sleeve and spindle tip displacements in spindle bearing systems equipped with angular contact ball bearings. The balance of axial forces produced in high-speed bearings is examined, with a particular consideration of centrifugal forces, gyroscopic moments, contact deformations, and contact angles. It has been shown that centrifugal forces acting on bearing balls do not cause sleeve axial shifts. Those sleeve shifts can only result from gyroscopic moments, and changes in spindle dimensions due to centrifugal forces. The proposed model has been verified experimentally, and can be used for compensation of spindle tip displacements.     

Characteristics of a spindle bearing system with a gear located on the bearing span

The spindle bearing system is the main source of the total cutting point compliance of machine tool structures. In this work, the static and dynamic characteristics of a spindle bearing system driven by a gear located on the bearing span were investigated using the analytical and finite element methods. Based on the calculated results, a prototype spindle bearing system was manufactured and its static and dynamic characteristics were measured. From the comparison of the experimental results with the calculated results, it was found that the finite element method predicted well the static and dynamic characteristics of the spindle bearing system.