Optimization of partially crowned roller profiles for tapered roller bearings

The roller profile plays a key role in the overall performance of roller bearings. In traditional profile design for roller bearings, the roller profile was often analyzed in terms of the bearing performance, particularly the fatigue life. However, the bearing dynamic stiffness and fatigue life were seldom considered simultaneously in the design of Tapered roller bearings (TRBs). Among the available roller profiles, the partially crowned roller profile has been acknowledged as one of the best from the viewpoint of the bearing fatigue life and stiffness characteristics. This paper presented a design optimization for the partially crowned roller profile to improve the performance of TRBs. Two profile parameters of rollers employed for TRBs including the central flat length and crown radius were investigated. The optimal design parameters for the roller profile were obtained in consideration of both bearing fatigue life and stiffness. The proposed design approach was useful and applicable for further geometrical optimization, manufacturing, and engineering application of rolling bearings.     

Fatigue Life of Tapered Roller Bearings under Minimal Lubricant Films

A series of fatigue tests were run on a 3.25 inch O.D. tapered roller bearing to establish the effect on bearing life of lubricant film thicknesses in the 0.5–4.0 micro-inch range. Based on the ratio of calculated film thickness to composite surface roughness, results from eleven individual tests indicate the bearings operated normally under conditions which should have resulted in drastic life reductions according to other investigators' results published in the literature.

In the tests fatigue life varied with film thickness raised to the 0.84 power with operating temperature and viscosity appearing to have influenced fatigue life over and above their influence through film thickness.

Several explanations of the observed results are discussed.     

圆锥滚子轴承失效分析

通过对某圆锥滚子轴承的失效分析,找出两公司圆锥滚子轴承在材料及制造方面存在的差异,指出轴承早期疲劳失效的原因,提出相应的改进建议,以提高圆锥滚子轴承使用寿命及可靠性。     

Optimizing the Design of Cluster Mill Rolling Bearings

The design of back-up roll bearings in cluster-type rolling mills has, historically, been dictated by past engineering trial and error experience. Thus, to cause the bearings to act, as nearly as practicable, similarly to conventionally supported bearings, the outer ring section is usually made very heavy precluding large ring deflections.

There exists controversy among bearing manufacturers as to whether a bearing having many rollers of small diameter or one having a smaller number of larger rollers is best in this application. The study herein presented examines bearing life under each condition while fully accounting for the effect of outer ring deflection on fatigue life.

The investigation further demonstrates that an optimum design with regard to outer ring section thickness in relation to diametral size and number of rollers per row does exist with respect to bearing fatigue life. Whether such design is compatible with possible outer ring destruction due to heavy roll loads can only be proved by on-site testing.     

A Fatigue Life Comparison of Two-Row Tapered Roller Bearings and Spherical Roller Bearings

Tests were run to compare the fatigue life of two-row tapered roller bearings to that of spherical roller bearings. Both bearing types had an outer diameter of 110 mm with the spherical roller bearing having a 22 percent larger dynamic radial load rating than the tapered roller bearings. All tests were run at 165 percent of the respective two-row dynamic radial load ratings. The results show that both the indirect mounting (double cup or outer ring) and the direct mounting (double cone or inner ring) tapered roller bearings gave significantly better fatigue lives than the spherical roller bearings. These results appear to contradict the present ISO 281 standard which assigns a 1.15 b_m rating factor to spherical roller bearings compared to a b_m rating factor of 1.10 for that of tapered roller bearings.     

轴承滚子凸度轮廓的最小二乘拟合与误差评定

为了实现对轴承滚子凸度轮廓误差的精确评定,依据圆弧修正型轴承滚子凸度素线轮廓的几何特征和形状误差的定义,基于最小二乘原理,研究了轴承凸度轮廓(两段圆弧和一段直线)的最小二乘拟合和误差评定方法。首先利用各测量点的曲率差值确定了圆弧段与直线段的相切参考点;其次分别选取两个参考点临近的测量点作为辅助相切参考点,并与对应的圆弧段测量点一起拟合出一系列的最小二乘圆弧并计算拟合误差;然后基于直线与两段圆弧相切的原则确定出一系列的直线方程并计算对应的直线度误差;通过比较判断最终确定出圆弧修正型轴承滚子凸度轮廓的最小二乘拟合及误差评定。实例结果表明:圆弧修正型凸度轮廓曲线的总误差0.020 9mm与文中设定标准凸度轮廓曲线引入的法向误差0.02mm相差4.5%。本方法可以有效的实现轴承凸度轮廓的拟合与误差评定,为平面多段曲线的最小二乘拟合提供了一种新的思路。     

圆锥滚子轴承滚子凸度设计

导圆锥滚子轴承是直升机传动系统中的重要组成元件,直母线圆锥滚子轴承存在"边缘效应"。研究表明,轴承的寿命与应力的7次方成反比。为了降低轴承工作过程中的应力水平,提高轴承寿命,需要准确设计不同工况条件下圆锥滚子的凸度值。本文通过有限元分析与Romax对比计算,得到Romax设计滚子凸度可以在保证计算精度的情况下,显著提高计算效率的结论。     

RV减速器转臂轴承的优化设计

为延长RV减速器疲劳寿命,利用遗传算法对RV减速器转臂轴承进行了设计优化。设定基本额定动载荷为目标函数,以轴承节圆直径、滚子直径、滚子数量、滚子有效接触长度为设计变量,从几何、强度、润滑和摩擦方面给出约束,并对优化结果进行灵敏度分析。优化结果表明,优化设计方法可以有效提高RV减速器的疲劳寿命。     

圆锥滚子轴承半凸滚子的优化研究

众所周知,滚子轮廓对圆锥滚子轴承的总体性能有着非常大的影响.在传统的滚子轴承外形尺寸的设计中,常常从轴承的疲劳寿命等方面对其进行分析,但很少同时考虑和分析滚子的动态刚度及疲劳寿命.从轴承的疲劳寿命和刚度特性来看,在现有的滚子类型中,半凸面滚子被认为是最佳的滚子轮廓之一.在对半凸面滚子进行优化设计过程中,重点研究了两个基...     

Study on design and simulation of a novel isolator cylindrical roller bearing

The sliding friction of the cylindrical roller bearing makes the internal resistance of the bearing large. Thus, this paper proposes to replace the cage with rolling isolators being placed between the cylindrical rollers, making the rub of all the elements be rolling friction. Therefore, the driving torque of the bearing is greatly reduced. First, the structure and working principle of this kind of bearing are described, the geometric parameter relationship of the roller and the isolator is analyzed, the feasible range of the parameters of the isolator is deduced based on the NFL203V type cageless bearing is proposed. Then, the ADAMS software is used for motion simulation of this novel cylindrical roller bearing. The best design plan is obtained through a comparison of the different schemes. Finally, experiments of bearing temperature are conducted, which shows the working temperature of the isolator cylindrical roller bearing is lower than that of the traditional roller bearings.

     

含水工况下T406对轴承疲劳寿命影响的试验研究

通过在滚子-钢球寿命试验机上测试圆柱滚子疲劳寿命评价含水工况下添加剂T406(苯三唑十八胺)对疲劳寿命的影响。应用光学显微镜,扫描电镜(SEM)和能量色散X射线光谱仪(EDS)分析滚子点蚀坑形貌和表面化学反应膜成分,对水和T406对轴承滚子接触疲劳寿命可能的影响机制进行分析。结果表明,在含水工况下添加剂T406能够提高滚子的疲劳寿命。T406通过在金属表面的聚集中和氢离子,从而阻止水对金属表面的有害影响,提高轴承疲劳寿命。     

新结构调心滚子轴承设计研究

通过对新结构调心滚子轴承的设计研究，阐明其结构特点、技术要点和创新点对该轴承的重承载性和寿命的影响。采用先进的优化设计理论，选取合理的曲率半径，运用先进的滚子自引导理论，设计出高技术含量、高承载性、高硬度、长寿命新结构调心滚子轴承。     

An experimental investigation of wear and fatigue life reduction of boundary lubricated spherical roller thrust bearings

Wear and fatigue life reduction in boundary lubricated spherical roller thrust bearings has been investigated. Previously presented results from measurements show that there is a significant change in the washer profile due to wear. This change in surface profile greatly affects the fatigue-life of the bearings. A fractional factor experiment series was used to study how the contacting surfaces of the bearing were affected by the rotational speed, load, hardness of the contacting surfaces and type of oil. The results show that the fatigue life and amount of wear on the washer surfaces were affected by the type of lubricant and rotational speed. A change of the load or a change of the hardness of the contacting surfaces did not influence the wear or the fatigue life of the contacting surfaces.     

Some aspects of the design of high speed roller bearings

High speed lightly loaded cylindrical roller bearings are prone to slip and lubricant starvation at the inner race - roller contacts. Both factors affect the oil film thickness which, in turn, influence the bearing life. Existing oil film thickness - life factors do no adequately consider these parameters It can be shown that the most important single factor is the cage speed; almost any variables that modify the conditions in the bearing do so by adjusting the speed of the cage itself. Curves are presented illustrating the influence of the bearing and chamber design and lubricant properties on the starved oil film thickness at the bearing inner contacts. It is shown that these values can be used to obtain improved life estimates     

Study on the Life Distribution and Reliability of Roller-Based Linear Bearing

A study on the life distribution and reliability for a roller guide with cage was carried out with a total number of 90 test samples in two lots (N _s = 38 and 52), and different fatigue life distribution functions, such as the two and three parameter Weibull distributions, and the log-normal distribution were used for analyzing the test data. The basic dynamic load rating formula standardized by ISO in 2004 was also compared with the life test data in relation to the effect of crowning on both ends of the carriage raceway. This study revealed the following: (1) the best fit for the life test data was achieved by the three-parameter Weibull distribution with the third parameter being the minimum life γ, using a Weibull slope of m = 27/20, and a load life exponent of 10/3. The log-normal distribution came second, and the two-parameter Weibull distribution third. (2) The test data did not fit with the two-parameter Weibull distribution using a Weibull slope of 9/8, which had been used in the ISO linear bearing standard. (3) Fatigue failure on the roller guide was initiated near the starting points of the crowning on both ends of the carriage raceway. Almost 70% of the test specimens were found to have uneven and inclined contact situations with the rollers. (4) The basic dynamic load ratings evaluated theoretically fit well to the life test results, while the λ b _m factors were also observed to fall within a suitable value range.     

基于机器视觉的圆柱滚子尺寸检测方法

以轴承圆柱滚子为研究对象,提出一种基于机器视觉的圆柱滚子尺寸检测方法,利用圆柱滚子的图像实现圆柱滚子直径与长度的同步检测。首先,对相机拍摄的圆柱滚子照片做预处理:使用灰度线性变换提高圆柱滚子与背景的对比度,再使用二值化阈值分割方法实现圆柱滚子图像的获取;然后采用Canny算子检测圆柱滚子边缘,为了获得圆柱滚子的直径与长度值,最后运用最小外接矩形拟合边缘。经过与人工检测结果对比,证明该检测方法检测结果准确。     

192308EK圆柱滚子轴承结构的改进

通过对轴承结构中的滚子尺寸、滚子数量、外圈滚道直径、止动槽直径公差及有效壁厚的改进，提高其使用的可靠性。     

高强螺纹滚压工艺的有限元模拟及试验研究

对高强螺纹进行滚压处理可有效提高螺纹结构的抗疲劳性能。为深入研究螺纹滚压工艺规律,以提高螺纹紧固件的抗疲劳性能,建立螺纹滚压工艺三维有限元模型,并基于该模型研究了滚轮参数对滚压后残余应力的影响规律,最终采用疲劳试验验证了该方法的有效性。结果表明:滚轮型面夹角、直径、型面圆弧半径等参数对滚压后引入的残余应力分布具有很大影响。滚轮型面夹角越小,滚压后引入的残余压应力层越深;较小的滚轮直径有利于引入较大的残余压应力和残余应力层深;较大的圆弧半径可获得较高的表面残余压应力和最大残余压应力,同时在一定范围内导致残余应力层深减小。疲劳试验结果表明,采用未经优化的滚轮强化后,螺纹疲劳寿命提高1.6倍,而采用经优化设计的滚压轮强化后,螺纹疲劳寿命提高4倍。该结果证实了基于有限元分析的滚轮优化方法的有效性。     

圆锥滚子轴承振动因素分析的定性融合方法

以乏信息系统理论为依据,提出因素分析的定性融合方法,以寻找影响圆锥滚子轴承振动的主要因素。试验研究发现,在测量条件下对试验轴承而言,滚子母线凸度、内圈和外圈滚道圆度误差是最重要的因素。     

超精密运动台激光测量模型及误差补偿算法

分析激光测量中阿贝误差与余弦误差产生的原因,分两种情况讨论阿贝误差与余弦误差对测量光程的影响：一是忽略激光干涉仪加工误差与安装误差的理想模型;二是考虑干涉仪加工误差与安装误差的非理想模型。计算两种情况下测量光束的光程长度,建立x、y方向直线测量位置不受运动台倾斜或旋转影响的测量模型,进而推导出运动台五自由度激光测量算法。实例证明该算法能有效地进行阿贝误差与余弦误差补偿,满足超精密运动的要求。该算法已成功应用于半导体加工设备中。