The role of nitrogen content on the rolling contact fatigue performance of En31 ball bearing steels

Using an accelerated service-simulation test, the role of nitrogen content on the rolling contact fatigue resistance of a range of En31 ball bearing steels was assessed. Nitrogen content appears to be a significant factor in steel performance. Air-melted neutral open hearth and acid open hearth materials, which were superior to air-melted basic electric arc steels, were comparatively low in nitrogen. With the basic electric arc materials there was a trend towards reduced rolling contact fatigue life with increased nitrogen content.     

Motion of a ball in a ball bearing

A magnetized ball rolling in a ball bearing induces an alternating current in a coil wound on the outer ring. The period of the current represents one revolution of the ball. Deviation from ideal motion of the ball occurs as slip and spin. The former is shown by the prolongation of the period. The latter causes fluctuation of the rolling axis relative to the magnetic axis of the ball. It can be easily estimated by measuring the variation of the amplitude of the current. Under radial load a considerable slip occurs at the unloaded side. It is found that the slip decreases exponentially with increase in speed. The magnitude and the direction of load, the lubicating condition and the radial clearance also affect the slip. In the special case where the ratio of the number of revolutions of the ball to that of the cage becomes nearly equal to an integral value, the deviation of the rolling axis shows a sharp increase, which often exceeds 70°. This deviation is due to the spinning motion of the ball during slipping.     

The nonlinear and ball pass effects of a ball bearing on rotor vibration

A ball bearing is generally assumed as a linear spring in rotor dynamic analysis. In real case, the force equilibrium of the bearing is changed as the relative position, of each ball with respect to the direction of radial force. So, the stiffness of the bearing is also changed and is a function of time and position. In this study, the nonlinear characteristics of a ball bearing are considered in analyzing the vibration response of a rotating shaft due to an unbalance force. A finite element method is used to analyze the vibration characteristics of a rotor-bearing system and a direct numerical integration is performed to calculate the transient response of the rotor system. The responses are converted to the frequency domain and the effects of the parametric excitation due to a ball bearing are examined. The test rig for the investigation of the effect of a ball bearing on the rotor vibration is set up and the results are compared with those of numerical calculation. The calculation results show that the amplitudes of the nonlinear model are larger than those of the linear one. The frequencies of the calculations can be matched to the measured frequencies.     

角接触球轴承的3D接触动态特性分析

基于弹性接触动力学理论,同时考虑转速,轴向力,径向力,摩擦力与离心力的影响,建立了轴承接触动力学模型,利用数值积分和数值仿真方法对其进行了时变的接触刚度、接触力和时变位移的振动分析.结果表明,考虑影响轴承振动位移的时变因素所获得的计算结果比用传统的轴承结合部等效参数计算结果要大,该方法有效地解决轴承转速、摩擦等时变因素影响下的时变位移等问题.仿真结果为机床主轴系统的动态设计和研究轴承的时变特性提供理论依据.     

Load-displacement relationship model and measurement of deep groove ball bearing and 4-point contact ball bearing

Journal of Mechanical Science and Technology - This paper established geometric coordination equations of deep groove ball bearings (DGBB) and 4-point ball bearings (4PBB) in which the contact...     

高速精密陶瓷球轴承与钢质球轴承的性能比较研究

角接触球轴承作为高速主轴的核心部件,其动力学特性对整机的切削性能和加工精度有重要的影响。本文根据Jones的套圈控制理论建立的动静分析法,建立了高速球轴承的拟动力学模型,基于该模型采用定量方法比较研究了陶瓷球轴承与钢质球轴承的性能差异,得到了若干有实用价值的研究结果。     

The contact forces of lip seals for a ball bearing

Simplified equations are derived for the evaluation of the axial contact forces for a special design of lip seal for bearings. The contact forces of the lip seals for a ball bearing are analysed as a function of the ratio of real contact length, the thickness of the seal lip, the inclined angle of the seal lip, and the deflected interference between the edge of the seal lip and the rotating inner ring. An experimental apparatus is developed for testing the seal lip contact forces. Using a non-linear FEM program, the contact force of the seal lip was analysed for various values of the deflected interference. The calculated results show that the deflected interference and the circumferential stress cause considerable change of contact forces for the low sealed lubricant pressure. The results of contact forces obtained from the derived equation for the contact force are in good agreement with experimental and numerical results.     

Modeling relations between physical properties and chemical composition of steels in quenched state

Linear statistical models with multiple parameters have been developed for predicting the magnitudes of the coercive force, saturation magnetization, electric conductivity, and hardness of highcarbon and alloyed steels of various chemical compositions quenched in the normal regimes.     

Thermo-mechanical analysis of angular contact ball bearing

The thermal-mechanical character, which is difficult to ensure because of the lack of a corresponding theory and tool, has a significant effect on the dynamics of bearings. It even leads to a sudden failure of bearings in a working situation. In this research, a thermal deformation model was established, based on the analysis of temperature effect on the basic size of angular contact ball bearing. And the transmission from rolling size to bearing axial stiffness was explicit. On the basis of the variation of Hertz contact stiffness and the change of initial contact angle of angular contact ball bearing caused by temperature rise, a “Thermo- mechanical” model of bearing was proposed. According to this model, using the corresponding calculation procedure programmed by MATLAB, the effect of bearing temperature on the axial stiffness has been studied. And the correctness of this model was verified with experiments. Some design suggestions have been made for the decision of bearing preload: to prevent the bearing failure caused by overheating.     

混合陶瓷球轴承多目标优化

混合陶瓷球轴承(Hybrid Ceramic Ball Bearing,HCBB)用Si3N4陶瓷球替换钢球,这两种材料性能差距较大,导致轴承寿命和发热量发生显著变化,需对HCBB进行多目标优化设计。提出高速HCBB多目标优化模型,目标函数为疲劳寿命和直接表征发热的自旋摩擦功率。用Ioannides-Harris理论计算HCBB寿命,用非劣排序遗传算法-II求解该多目标优化问题。结果显示优化的HCBB显著优于当前设计。     

A preliminary assessment of high speed tool steels manufactured from powder for rolling bearing materials

High speed tool steels manufactured from powder were assessed under arduous conditions of rolling contact and compared with conventional materials using an accelerated service simulation test. Metallographic investigations revealed factors influencing performance. Material manufactured from powder was generally found to be inferior to vacuum-remelted material due to poor structure, porosity, high interstitial nitrogen content and other manufacturing variables. Sound homogeneous material with uniform fine carbide distribution and gas content comparable with those of conventionally cast material appears potentially suitable for rolling bearings. The improved performance at elevated temperature may be due to metallographic changes, deleterious interstitial nitrogen content being reduced by a precipitation process.     

硬车削滚动轴承套圈的试验研究

针对滚动轴承套圈硬车削加工过程中表面质量存在的问题,对硬车削过程中切削用量和刀具参数对表面粗糙度的影响进行了研究,采用CBN刀具进行了6205滚动轴承套圈的硬车削加工试验,将进给量、切削速度、切削深度和刀尖圆弧半径作为试验因子,通过正交试验分析了它们对零件加工后表面粗糙度的影响规律,并归纳出了该试验范围内的最佳切削用量和刀具参数组合。研究结果表明,进给量对表面粗糙度的影响最大,刀尖圆弧半径对表面粗糙度的影响次之,切削速度对表面粗糙度的有一定影响,切削深度对表面粗糙度的影响非常小。     

带装球缺口深沟球轴承装配工艺的改进

针对带装球缺口的深沟球轴承手工压球工艺生产效率低、劳动强度大、且容易漏球的问题,研制了自动装球机,实现了自动装球、自动下料的功能,提高了生产效率、自动化程度和可靠性,减轻了工人的劳动强度。     

滚珠丝杠副的计算机辅助设计

滚珠丝杠副是目前直线运动平台中应用最广泛的高精度、高效率传动和定位部件。这里文介绍了利用VisualBasic6.0和Access的数据接口,对滚珠丝杠副进行计算机辅助设计的方法。     

深沟球轴承早期失效分析

通过对故障轴承的综合检测及对检测结果的分析,确定该轴承工作过程中承受了过大的轴向负荷,是造成轴承早期失效的原因。     

Hydrogen embrittlement of a stainless ball bearing steel

Ball bearing steels are susceptible to hydrogen embrittlement caused by lubricant degradation. It has been shown that hydrogen embrittlement of 440C stainless steels is associated with the existence of M₇C₃ carbides. The behaviour of M₇C₃ carbides during hydrogen embrittlement was investigated by classical rotating beam fatigue and tensile tests of specimens into which hydrogen had been introduced by cathodic charging. The effects of the current density, the time and the stress of charging and the relaxation time between charging and mechanical testing were assessed. The hydrogen embrittlement was characterized by using tritiated water. High resolution autoradiography and scanning electron microscopy were used to determine the location of the hydrogen in the martensitic matrix relative to the M₇C₃ carbides and to the interfaces between the M₇C₃ carbides and small M₂₃C₆ carbides.     

某深沟球轴承失效分析

某深沟球轴承在使用中出现轴承滚道剥落现象。经过故障特征、理化检验等分析后发现,由于轴承选型及使用不当是导致其剥落失效的原因。     

陶瓷球轴承的应用及市场分析

阐述了高速高精度主轴轴承用氮化硅陶瓷滚动体材料的性能特点与钢制滚动体的性能对比,及目前陶瓷球轴承市场分析和展望。