Mechanical behaviors of cross roller bearings with raceway roundness error

Taking the raceway roundness error into account,mechanical characteristics of cross roller bearings(CRBs)were investigated.A static analysis model of CRBs considering the raceway roundness error was established.Based on this model,the rotational accuracy and load distribution of CRBs under constraints of geometry and external loads were derived.The fatigue life of CRBs with roundness error was calculated by applying Palmgren-Miner linear cumulative damage theory.The influence of inner and outer raceway roundness error on the performance of the CRBs,such as rotational accuracy,load distribution,and fatigue life,was studied through the analysis of examples.The results indicate that the influence of roundness error on the rotating inner raceway is more significant than that of roundness error on the nonrotating outer raceway.The roundness error on the rotating inner raceway always degrades the performance of CRBs.However,a proper roundness error on the nonrotating outer raceway can reduce the loads acting on the rollers and thus improve the fatigue life of CRBs.The effect of the roundness error amplitude on the bearing performance is ordinal,whereas the effect of the roundness order on the bearing performance is not in order.

Roundness error evaluation by minimum zone circle via microscope inspection

Utilizing the convex hull theory, a novel minimum zone circle （MZC） method, named im- proved minimum zone circle （IMZC） was developed in this paper. There were three steps for IMZC to evaluate the roundness error. Firstly, with the convex hull algorithm, data points on the circle contour were categorized into two sets to determine two concentric circles which contained all points of the contour. Secondly, vertexes of the minimum circumscribed circle and the maximum inscribed circle were found out from the previously determined two sets, and then four tangent points for de- termining the two concentric circles were also found out. Lastly, according to the evaluation using the MZC method, the roundness error was figured out. In this paper l IMZC was used to evaluate roundness errors of some micro parts. The evaluation results showed that the measurement precision using the IMZC method was higher than the least squared circle （LSC） method for the same set of data points, and IMZC had the same accuracy as the traditional MZC but dramatically shortened com- putation time. The computation time of IMZC was 6. 89% of the traditional MZC.

A New Algorithm of Roundness Error Separation Technique of Three-point Method

Through the analysis of roundness error separation technique of three-point method and based on the invariability and periodicity of the geometrical characteristic of measured round contour, a new matrix algorithm, which can be used to solve directly the roundness of the measured round contour without Fourier transform, is presented. On the basis of the research and analysis of the rotation error movement which is separated by using the three-point method, a mathematical equation is derived, which can be used to separate the eccentric motion of least square center of measured round contour and the pure rotation motion error of spindle in rotation motion. The correctness of this method is validated by means of simulation.

Multi-Aspect Value of Measuring Systems and Methods Based on the Results of Roundness Measurements

The increase of quality consciousness brings about the growth of significance of metrological systems. Besides the significance, the level of automatization, flexibility, accuracy, et al. have advanced. The modern measuring systems are constructed so that nearly all necessary dimensional characteristics can be measured with them. However, conventional measuring systems are provided for particular mode measurements. This research paper presents and compares several conventional and modem measuring systems and methods. The measured value is roundness, one of the basic shapes of cross section in mechanical engineering. This paper arises in search of answers for the question whether conventional measuring techniques and equipments are made redundant because of the modern ones. In what segments and in which criterion are modem methods preferable？

On-Line Measurement Method for Diameter and Roundness Error of Balls

This paper presents an on-line measurement method for the diameter and roundness error of balls.An easy-installation rotary scanning system,which integrates the principles of the diameter and the roundness measurements,is constructed.The rotary scanning system consists of a rotary stage,a linear stage,and two sensors with a什at probe.Two sensors are initially installed on the linear stage and contact each other.The outputs of two sensors are reset to zero at first.The ball is then mounted on the rotary stage and positioned between two flat probes.The variations of the diameter and the roundness error of the ball at each angular position can be directly recorded by two sensors when the ball is rotated by the rotary stage.Substituting the outputs of two sensors into the proposed mathematical models,the diameter and roundness error can be evaluated.The effects of the alignment error induced by the spindle error of the rotary stage and the titling error and the eccentric error of the ball on the measurement accuracy can be self-separated in the proposed on-line measurement method.A series of experiments are carried out to verify the effectiveness and the capability of the proposed on-line measurement method and the designed rotary scanning system.The designed system is easy to construct both in the laboratory environment and the factory field.

Three-Probe Error Separation with Chromatic Confocal Sensors for Roundness Measurement

In this study,three-probe error separation was developed with three chromatic confocal displacement sensors for roundness measurement.Here,the harmonic suppression is discussed first to set suitable orientation angles among three sensors.Monte Carlo simulation is utilized to test the error separation and optimize the orientation angles and off-axial distance.The experimental setup is established using chromatic confocal sensors with a precise rotary platform.The experimental results show that the measured roundness with an orientation-angle combination of(0°,90.1°,and 178.6°)is much better than that of another nonoptimal selection(0°,90.4°,and 177.4°).The roundness error is only 0.7%between the proposed measurement system and an expensive ultraprecision roundness meter.Furthermore,it is proven that the eccentricity distance should be decreased as small as possible to improve the measurement accuracy.In sum,this paper proposes a feasible method for roundness measurement with reliable simulations,easily integrated sensors,and an ordinary precision rotary platform.

Vision testing method for diameter,roundness and hardness of table tennis ball

Under the premise of fully respecting current national standard of table tennis ball,this paper presents an integrated and effective method for testing diameter,roundness and hardness of table tennis ball based on vision measurement. Firstly,camera calibration is performed by 40 mm gauge block to capture the images of table tennis ball in static and pressed state in an appropriate lighting condition. Then image binarization and extraction of image contour are carried out. The least square method is used to fit its center. Finally,the diameter,roundness and hardness are calculated. The measurement data are analyzed by using the method presented in this paper for table tennis ball with known parameter data and with unknown parameter data. Experimental results show that this method can improve measurement accuracy and provide a technical basis for the online testing and integration measurement of table tennis ball.

圆结构光系统深孔圆度测量方法研究

圆结构光系统测量深孔(通孔)圆度时存在激光器、相机和深孔难以保持平行或同轴的问题,导致无法测量准确的圆截面,从而产生系统误差。搭建了基于圆结构光的测量系统,分析了系统误差的产生机理并提出了一种基于圆结构光系统测量圆度的方法,可对系统误差进行一定补偿:首先,获取待测深孔的内表面高分辨率三维点云,拟合点云轴线,通过刚体变换将三维点云变换到深孔轴线与相机光轴平行的位置;然后,选定一个测量截面,搜索该截面上的点和与该截面范围较近的点作为圆度评定点;最后,采用网格搜索算法完成圆度评定。测量实验的结果表明,该方法对于圆度误差的补偿效果良好,其中测量不确定度为4.78μm。

大直径钢筒圆度异常区快速检测方法

大直径钢筒在制作、运输、安装及运行时均可能因某些原因导致其出现一个或多个圆度异常区,以至于不满足设备验收和运行的相关要求。目前,针对大直径钢筒圆度异常的检测方法均较为复杂,并不适合快速检出。为此,本文基于三坐标测量原理,结合高精度全站仪的非接触自动测量模式,并采用Matlab编制了自动搜索程序,提出了大直径钢筒圆度异常区的快速检测方法。通过AutoCAD算例模拟和现场实测,结果表明,该检测方法不仅速度快,且可通过增加测点密度实现大幅提高检出精度,为后续修复和改进工作提供准确数据。

一维平流方程迎风格式的最优时空步长

在考虑舍入误差影响的情况下,研究一维平流方程迎风格式最优时空步长的选取.首先,分析每一时间层产生的离散误差和舍入误差,以及2种误差向高时间层传播的累积,得到数值解总误差的理论上界;然后推导出最优时间步长和最优空间步长的理论公式,进而得到2种不同机器精度下最优时间步长之比满足的一个仅与机器精度有关的普适关系;最后通过数值算例验证了结论的可靠性.

曲轴连杆颈圆度在线测量机构设计与运动分析

曲轴随动磨削时,连杆颈的偏心旋转运动导致其中心位置不断变化,使得常规方法无法直接用于目标连杆颈圆度测量。为解决这一难题,文中提出了一种采用机械臂与V形测量机构相结合的设计方案,将V形块作为机械臂末端执行器,通过控制机械臂改变测量机构位置,抵消因连杆颈偏心转动导致的位置变化,实现连杆颈的圆度在线测量。基于D-H法,对所设计的曲轴连杆颈圆度在线测量机构的正逆运动方程进行了推导与分析,并通过Simulink软件验证推导运动方程的正确性。最后,采用图形法分析了机构工作空间,结果表明:所设计的机构完全满足使用要求。

具有圆度误差的径向金属密封接触应力研究

由于加工圆度误差的影响,井下流量控制阀径向金属密封接触应力分布不均匀,从而影响密封性能。利用有限元方法研究具有圆度误差的径向金属密封唇部接触应力分布,并分析圆度误差对径向金属密封接触应力的影响;基于有限元分析结果提出径向金属密封接触应力分布的理论解析式,并进行误差分析。具有圆度误差的径向金属密封唇部接触应力分布的理论解与数值解相符,各参数引起的最大接触应力的平均相对误差约为10%。根据具有圆度误差的径向金属密封副接触应力的分布规律,提出合理的过盈量函数,修正了径向金属密封轴对称结构的悬臂梁模型的接触应力理论关系式,得出了圆度误差下的径向金属密封接触应力分布规律。研究结果为井下流量控制阀径向金属密封的设计提供了理论指导。

基于傅里叶变换与统计检验的圆度误差分离技术研究

采用傅里叶变换及数理统计假设检验的方法对圆度误差进行分离。针对圆轮廓的高精度测量数据,通过最小区域法拟合圆心。应用傅里叶变换将圆轮廓信号转换成谐波信号,从理想圆轮廓模型出发,逐步添加傅里叶分量,迭代过程中通过偏F检验构造包含未知系统形状误差的主导性模型。通过自相关法检验、卡方检验及J-B检验获取残余的显著性傅里叶分量,进一步构建显著性模型,实现圆度误差中系统误差的分离。通过数控加工16个圆孔的实验数据分析,证明了该方法可以对圆度误差进行有效分离。

基于改进乌鸦搜索算法评定圆度误差

针对传统启发式智能优化算法评定圆度误差计算效率低且容易陷入局部最优解的问题,提出采用改进乌鸦搜索算法评定圆度误差。根据最小区域拟合准则建立乌鸦搜索算法评定圆度误差数学模型,并引入权重系数,提高算法全局搜索能力,同时设定最小二乘圆心附近为乌鸦搜索初始位置,提高算法搜索效率。最后通过模拟和实验验证了所提算法的准确性和高效性,并通过多组数据对比发现改进乌鸦搜索算法的全局搜索能力较遗传算法(GA)、粒子群算法(PSO)和传统乌鸦搜索算法(CSA)得到明显提升。

基于线激光的压缩机曲轴圆度和平面度测量

目前人工使用千分表测量空调压缩机曲轴圆度和平面度时存在易伤工件表面、效率低和不能精确评定等问题。针对上述问题,设计了一套基于线激光位移传感器的空调压缩机曲轴圆度和平面度非接触式测量系统。首先,通过测量标准量棒,提出一种系统误差的标定方法;其次,基于线激光采样数据,开发了一种曲轴横截面圆度测点的提取算法,并将系统误差用于测点补偿,实现曲轴圆度测量;接着根据曲轴平面测点间的斜率分离出轮廓线,通过均匀下采样方法获取精简点云数据并采用最小二乘法实现曲轴平面度测量;最后,基于上述方法开展了曲轴圆度和平面度的测量实验。实验结果表明:该测量系统的圆度测量精度<4μm,平面度测量精度<2μm,圆度重复度测量误差<0.8μm,平面度重复度测量误差<0.3μm,满足曲轴圆度和平面度快速准确的测量需求。

基于fminimax优化函数的圆度误差评定

依据圆度误差标注代号和附加符号的含义,基于最小外接法、最大内切法和最小区域法分别建立了参考圆的圆心坐标优化目标函数和圆度误差评定模型,采用MATLAB软件编写了参考圆的圆心坐标优化目标函数子程序和圆度误差评定子程序,给出了圆度误差评定中fminimax优化函数调用方法。用Talyrond 585LT圆柱度测量仪对三个试样的圆周轮廓进行了提取,基于最小二乘法、最小外接法、最大内切法和最小区域法对提取的圆周轮廓分别进行了圆度误差评定。研究了优化搜索范围对圆度误差评定结果的影响,并将fminimax优化函数圆度误差评定的优化符合度与其他优化方法圆度误差评定的优化符合度进行了比较。fminimax优化函数的应用结果表明,评定结果精度高于或等于其他优化方法评定结果的精度,可满足圆度误差评定的需要。

基于SDES和双轮差错控制的大数据集成安全系统

针对大数据传输中的数据机密性、完整性和数据丢失等问题,提出一种基于简化数据加密标准(Simplified Data Encryption Standard,SDES)和双轮差错控制的大数据集成安全系统。使用SDES加密算法生成加密字符串,并设计意外数据丢失备份系统以提高机密性和防止意外数据丢失。基于双轮差错控制以较低的空间开销控制传输过程中包含的任意数量的离散或连续错误位,基于固定长度编码(Fixed Length Coding,FLC)的无损压缩技术来减少数据开销。该算法具有较高的AE值、熵和压缩百分比,具有提供更高的数据机密性和完整性的潜力。

轴承套圈电磁无心磨削成圆误差解析和仿真

针对电磁无心磨削成圆过程和磨床加工性能的高精度预测和分析,研究了轴承套圈电磁无心磨削成圆误差的生成机制。建立以几何条件、加工参数和机床刚度为参数的,包含几何误差、静态误差和动态误差的解析方程,通过利用成圆误差方程对轴承套圈表面圆度误差进行迭代,可以在时域范围内对轴承套圈表面圆度误差的再生过程进行数值仿真,提供了一种预测轴承套圈表面圆度误差变化的仿真模型,为有效预测磨削性能和轴承套圈成圆过程提供了可靠的分析手段。通过同步仿真与实验条件参数,得到的仿真结果与实验结果的相对误差为8.04%。结果显示,所建立的综合模型可以完成成圆过程的分析并预测工件最终轮廓。

基于机器视觉的小型零件圆度测量

针对小型零件圆度误差测量效率低、精度不稳定等问题,提出了一种基于机器视觉的小型零件圆度测量方法。通过建立机器视觉检测平台,获得零件图像。经过预处理后,通过Canny算子结合8领域扩张算法划定感兴趣区域,采用多项式插值亚像素边缘检测算法获得边缘坐标;然后,利用改进区域搜索算法确定准圆心,并通过最小区域法的几何结构找出最小区域圆心,从而计算圆度误差。实验结果表明,圆度误差的测量重复精度为8.1μm,能够实现小型零件的非接触测量。

基于改进蝙蝠算法的最小区域法圆度误差评定

圆度是轴类机械产品几何精度评价的核心指标之一,其直接影响到产品的性能和寿命,准确、快速、规范的进行零件圆度误差评定一直是计量领域研究的热点。因此,提出了一种基于改进蝙蝠算法的最小区域法圆度误差评定方法,该方法利用蝙蝠算法的种群寻优能力,结合最小区域法对圆度误差模型中的目标圆心进行快速寻优,进而计算求解出圆度误差值。改进的蝙蝠算法通过增加混沌惯性权重、自适应参数等方法来有效避免算法在圆度误差评定中陷入局部最优,并改善评定准确性和稳定性。通过对实测数据进行实验验证和分析对比,结果表明提出的方法在圆度误差评定中寻优速度明显优于遗传算法,评定精度和稳定性较最小二乘法有较大提升,验证了该方法在最小区域法圆度误差评定应用中的可行性。