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。     

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。     

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.     

空心轴类件楔横轧仿真及壁厚变化规律

基于Deform-3D软件,建立了平楔楔横轧成形空心轴类件三维刚-塑性大变形热应力耦合有限元模型.通过模拟仿真与实验数据对比,验证了该模型的正确性,并在此模型基础上,应用楔横轧各工艺参数的正交试验,分析了空心坯料的成形性及壁厚的变化规律.结果表明:所轧空心轴类件的壁厚对比度与成形角、展宽角成正比,与断面收缩率成反比.研究结果对轧制空心阶梯轴的应用以及准确预测空心轴类件壁厚的变化具有指导意义和实用价值.     

空心轴壁厚差的超声波测量

给出了NOVASCOPE4000型超声测厚仪对某长空心轴壁厚的实测结果，分析了测量精度，提出了获得最佳精度的方法。     

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。     

基于Deform-3D的风机主轴空心轴预制坯成形优化

基于有限元分析软件Deform-3D建立了42CrMo4钢风机主轴1∶10等比例缩小的热力耦合三维有限元模型。为了对风机主轴空心轴预制坯进行成形优化,设计了一套专用于风机主轴空心轴预制坯锻造的新型模具。在Deform-3D中将常规风机主轴坯料模锻成形过程与采用新型模具的风机主轴空心轴预制坯成形过程进行等条件对比研究,分别从法兰端成形效果、轴身下料量以及等效应变、金属流动速度场、主轴所需成形力等的变化规律方面进行参数对比研究,验证了采用新型模具成形风机主轴空心轴预制坯的可行性,为优化风机主轴空心轴的实际生产流程提供了一定的参考。     

卧式多轴自动车床主轴静刚度初探

为了提供设计时评定主轴刚度和给定优化设计的刚度目标,文章采用有限元法对国产8种卧式多轴自动车床和国外5种同类型机床主轴计算,得到计算的主轴静刚度数据.从标准资料整机刚度的要求推算出一系列主轴静刚度数据,然后考虑到不同规格机床结构上的因素,将上述两组数据合并处理,以回归方式得到一个可供参考的参数方程.     

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。     

用故障诊断方法判断机床主轴轴承的工作状态

论文阐述了利用轴承振动信号可判断机床主轴轴承的工作状态，通过频谱分析可对轴承进行故障诊断及预紧力确定；应用B＆K2148采集振动信号，MATLAB进行数据处理，对CKS6116型机床主轴前轴承进行了故障诊断与预紧力分析并取得了满意的效果。     

Thermo-mechanical model of spindles

This paper presents a Finite-Element-method-based thermo-mechanical model of spindles with rolling bearings. The heat generated in the bearings and the motor is transferred to the ambient air, the motor coolant and the spindle structure, and causes thermal expansion of spindle parts. The experimentally validated thermo-mechanical spindle model predicts temperature distribution and thermal growth, as well as bearing stiffness and contact loads, under specified operating conditions. Transient changes in temperatures, deformations, viscosity of the lubricant, and bearing stiffness are considered in the solution. The predicted bearing properties are used to estimate the changes in the dynamic behavior of spindles.     

Development of a newly structured variable preload control device for a spindle rolling bearing by using an electromagnet

For high speed and high efficiency machining, the spindle of modern machine tools simultaneously requires high speed and high stiffness characteristics, and its range of use rotation is becoming wider. Both heavy cutting at low speed and light cutting at high speed must be carried out successively in series with a single machine tool spindle. As such, many studies are being carried out on variable preload control methods that apply a preload to a spindle rolling bearing, as an alternative to the existing fixed position preload and constant pressure preload methods. This paper introduces a newly structured variable preload control device that can arbitrarily adjust the preload applied to spindles employing a rolling bearing. The device controls the coil current on an electromagnet and thereby uses the magnetic force between the electromagnet and a magnetic substance to arbitrarily control the preload applied to the rolling bearing during operation. A prototype for the variable preload control device of the proposed structure was created and a functionality test was then carried out with a test bench prepared using a load cell. The operating principle of the proposed device was verified and the interrelationships between the coil current on the electromagnet and the preload applied to rolling bearing were analyzed through the functionality test. Lastly, the fabricated variable preload control device was applied to a prototype of a spindle system, and a rigidity test was carried out. The test results confirmed that the variable preload control device operates properly and smoothly.     

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.     

对高速电主轴静刚度的测试及分析

为研究高速电主轴静刚度的特性,利用DH3818静态应变测试仪,以高速电主轴为本体,研究高速电主轴静刚度与作用在电主轴上的力之间的关系。使用静态应变测试仪和力传感器在电主轴处于稳定状态时对1.5×10~4r/min电主轴和6×10~4r/min电主轴的径向刚度和轴向刚度进行测试,通过测试得知:高速电主轴静刚度大小与端部变形量成反比。对比分析1.5×10~4r/min电主轴轴向刚度与径向刚度,可知电主轴径向刚度远远大于轴向刚度;对比分析1.5×10~4r/min与6×10~4r/min电主轴径向刚度,可知最高转速低的电主轴比最高转速高的电主轴刚度大。又因为过低的静刚度会对数控机床的性能造成影响,所以提高电主轴静刚度也可使机床的性能得到提高。     

Development of automatic variable preload device for spindle bearing by using centrifugal force

Machine tool spindles of late require high stiffness and fast rotation characteristics all at once for high-speed, high-efficient processing, as well as for a wide range of use rotation. As such, many studies are being carried out on automatic variable preload control methods that apply a preload to a spindle rolling bearing as an alternative to the existing fixed position preload and constant pressure preload methods. This paper introduces a newly structured automatic variable preload device that can automatically adjust the preload applied to spindles employing a rolling bearing. It proposes an automatic variable preload device with a completely new composition comprising of a main bearing to which the preload is applied, an auxiliary bearing that conveys the force and a centrifugal element that converts the centrifugal force into a force in the axial direction, and a constant pressure preload spring that applies the initial preload to the main bearing. Other changes in the centrifugal force are also presented. The proposed composition was validated through a contact nonlinear analysis, and the design data necessary to create a prototype were obtained. A prototype for the automatic variable preload device using centrifugal force was then created and tested to confirm that the preload device of the proposed structure runs properly and smoothly.     

钢管热连轧过程横断面壁厚变化的三维有限元模拟

针对20号钢Φ119.0mm×9.25mm规格全浮动芯棒无缝钢管8机架连轧过程进行了有限元模拟仿真分析,得到了热连轧管各机架出口等效塑性应变以及荒管壁厚变化情况,分析了轧制力和芯棒力的变化特点。研究表明,连轧管减壁量和外直径变化主要集中于开始第1~第6个机架,在第7、第8机架减壁作用很小,最终荒管壁厚均匀,且形状圆整。稳定连轧阶段的轧制力依轧制顺序呈递减趋势,第7、第8机架轧制力很小;同时芯棒力大于各机架轧制力,钢管内壁承受的作用力和塑性应变较大,应对芯棒表面进行合理润滑。模拟得到的壁厚、外径及轧制压力与实测结果吻合较好。     

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.     

齿轮温锻组合凹模设计

运用Pro/E 4.0构建齿轮模型得出齿轮横截面积,把凹模齿形部分看成当量圆,通过齿轮横截面积得到当量直径,从而利用Lame公式理论计算与经验数据的有效结合,对齿轮温锻成形的组合凹模进行优化设计和强度校核。     

滚压参数对螺纹成形影响的实验研究

冷滚压法是加工优质高精螺纹件的一种先进方法,在实际生产加工时通过在数控系统中设置滚丝机的主轴转速、滚丝轮进给速度和精整时间进行加工。本文通过对主轴转速、滚丝轮进给速度和精整时间三因素进行正交实验,分析这三个参数对螺纹外径和加工过程中螺纹温升的影响,得出各因素对这两个指标的影响次序,综合分析外径和温升获得较优滚压参数,为实际生产时合理设置滚压参数提供实验依据。     

An integrated thermo-mechanical-dynamic model to characterize motorized machine tool spindles during very high speed rotation

High speed machining (HSM) is a promising technology for drastically increasing productivity and reducing production costs. Development of high-speed spindle technology is strategically critical to the implementation of HSM. Compared to conventional spindles, motorized spindles are equipped with built-in motors for better power transmission and balancing to achieve high-speed operation. However, the built-in motor introduces a great amount of heat into the spindle system as well as additional mass to the spindle shaft, thus complicating its thermo-mechanical-dynamic behaviors. This paper presents an integrated model with experimental validation and sensitivity analysis for studying various thermo-mechanical-dynamic spindle behaviors at high speeds. Specifically, the following effects are investigated: the bearing preload effects on bearing stiffness, and subsequently on overall spindle dynamics; high-speed rotational effects, including centrifugal forces and gyroscopic moments on the spindle shaft and, subsequently, on overall spindle dynamics; and the spindle dynamics on the cutting point receptance. The proposed integrated model is a useful tool for differentiating quantitatively different effects on the spindle behaviors. The results show that a motorized spindle softens at high speeds mainly due to the centrifugal effect on the spindle shaft.