Experimental load distributions for double pitch steel roller chains on steel sprockets

An experimental study was conducted to measure the load distribution in steel roller chains on steel sprockets and determine the effect of lubrication, misalignment, sprocket speed of rotation at low speeds, and slack-side load. A chain load distribution test machine was designed and constructed to conduct this investigation. Theoretical results obtained from a geometric progression load distribution model were compared to the experimental results.     

刮板输送机链轮磨损与圆环链形变之间的关系

采用数值分析与试验结合的方法分析了圆环链形变与驱动链轮磨损之间的关系。建立了圆环链有限元模型,分析了标准圆环链在不同负载下圆弧段的弹性形变,数值计算结果表明：在拉伸负载作用下,圆环链圆弧段为椭圆,椭圆长短轴之差随负载增加而增大,当负载接近弹性极限载荷时,圆环链椭圆弧段出现凹弧;采用柔性三坐标仪检测磨损前后驱动链轮链窝曲面并进行分析后发现,链轮链窝在准线方向磨损趋于均匀,母线方向磨损与圆环链形变之间存在关联。测试链轮母线磨损与匹配圆环链21.4%弹性极限载荷时外廓一致。最后得出了圆环链拉伸方向为短轴的椭圆环链或将有利于缓减链轮链窝曲面磨损的结论。     

基于ObjectARX的高速滚子链链轮设计

应用基于ObjectARX的AutoCAD二次开发技术实现滚子链链轮的虚拟加工和设计过程。通过模拟链条与链轮的近似共轭啮合过程,实现链轮虚拟加工过程,得到满足近似共轭啮合的链轮齿廓。链轮虚拟加工包络成形的原理是将链条滚子表面假想为刀具,切制链轮毛坯,链轮轮齿齿面即链条滚子表面在相对运动过程中在链轮毛坯上形成的包络。所得链轮齿廓曲线对于改善滚子链链轮的设计,提高滚子链在高速下的使用性能具有重要借鉴意义。     

Four-square sprocket test machineMachine d'essai en boucle ferme pour les roues a chaines

A 4-square sprocket test machine was built to obtain load vs cycle life data for various chain and sprocket geometry and material combinations. Sprockets were evaluated at various rotational speeds and chain loads that provided accelerated failures. Instrumentation on the machine recorded total sprocket cycles and a sensing switch automatically shut-off the machine when a failure occurred in the sprocket-chain system. Failure was defined as the point at which the chain-sprocket system ceased to function normally. In this paper, the 4-square sprocket test machine is described, preliminary load-cycle life results are given, and an SEM study of failed sprockets is presented.     

Rigid-flexible coupling dynamic modeling and characteristic analysis of the chain ramming mechanism

The previous studies on the dynamic characteristics of chain ramming mechanism have ignored the linkage effect of factors such as the elastic deformation of components, transmission clearance, stiffness of support body. In the model established in this paper, of which the effectiveness is verified by comparing with the experimental data, the influence of the main factors such as the elastic deformation of the chain link, the transmission clearance, the stiffness of the support body of the dynamic component and the linkage effect are all considered. The results show that the support stiffness of the sprocket shaft and the transversal support stiffness of the oil cylinder affect the longitudinal vibration of the chain. The chain link/roller clearance affects the longitudinal vibration of the chain. The track/roller clearance affects the transversal vibration of the chain at the beginning time of the ramming process and during the deceleration of the projectile.

     

线接触问题的弹性趋近量与滚子轴承的载荷分布

在对迄今为止所出现的各种线接触问题弹性趋近量分析方法进行全面阐述的基础上，就一些主要的弹性趋近量算式及其在滚子轴承载荷分布计算中的应用进行了求解和对比分析，分析表明三体接触时采用H．Zantopulos公式的结果最差，而在滚子轴承载荷分布的理论分析体系中，G.Lundberg、A.Palmgren、Luc Houpert以及改进的切片法等理论的计算结果相差不大，可以根据需要选用。     

齿形链传动啮合冲击机理

在齿形链传动中,链条承受周期性的交变载荷,其中链节啮入轮齿时产生的冲击栽荷影响较大。通过研究标准链条分别与直齿链轮和渐开线齿链轮啮合的啮合冲击,分析发现在链轮上采用渐开线齿能减小链条与链轮啮合瞬间的法向冲击速度,进而降低链条与链轮的啮入冲击。     

On the analyses of sprocket load distributionAnalyse de la distribution des charges dans les roues dentees

This paper presents a spring model analysis for the load distribution in chains and in sprocket teeth and compares the results with those from a traditional force-balance analysis which does not include a consideration of elastic properties.     

空心圆柱滚子轴承刚度分析

从空心圆柱滚子轴承变形协调关系出发,通过受力分析,建立各滚子载荷和外负荷的力学平衡方程,再运用当量弹性模量的方法,由帕姆格林公式确定负荷与变形间的关系式,求解了空心圆柱滚子轴承的负荷分布,据此导出了空心圆柱滚子轴承刚度的计算公式,并深入地分析了滚子空心度、外负荷、轴承转速和滚子数等对刚度的影响规律。研究结果表明：空心圆柱滚子轴承的刚度随空心度的增大而减小,随滚子个数的增加而增大,且外负荷和轴承转速会根据滚子的不同空心度表现出不同的变化规律。
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Analyses of thermal hydrodynamic lubrication in high-speed rolling. Part I: the effect of the roller's elastic deformation

A study of thermal hydrodynamic lubrication for high-speed strip rolling, which includes the roller's elastic deformation, was developed for a lubricant whose rheological behaviour satisfies the Barus' model. The difference in lubricating performances between an elastic roller and a rigid roller was assessed using parameters such as film thickness and pressure; temperature distributions in the fluid film, roller, and workpiece; separating force and shear torque. The elastic roller was made either of a unique material or its substrate was coated with one layer of a harder material to improve the wear resistance. The elastic deformation of the roller was obtained with the aid of Hitchcock's elastic-deformation theory and the biharmonic equation of Airy's stress function. It was found that the elastic deformation produces a substantial effect on some rolling characteristics.     

On the dynamic performance of roller bearings operating under low rotational speeds with consideration of surface roughness

The dynamic behavior of radially-loaded roller bearings operating at high loads and low speeds with different surface roughness values is investigated. The simulations take into account different lubrication regimes (rigid solid–isoviscous, elastic solid–isoviscous, rigid solid–piezoviscous and elastic solid–piezoviscous) in the loaded and unloaded sections of the bearing. The simulation results provide a detailed understanding of the variation of the film thickness, wear rate and heat generation between the rollers and the raceways as the rollers travel in the orbital direction. Simulation results reveal that an increase in the radial load results in a proportional increase in the wear rate and an exponential increase in the heat generation, although it does not affect the film thickness noticeably.     

链轮插齿刀的齿形设计

论述了滚子链轮插齿加工用三圆弧链轮插齿刀和渐开线链轮插齿刀的齿形设计及其应用,可供设计与应用参考。     

双节距滚子链链轮设计计算新方法

本文给出了一种双节距滚子链链轮设计计算新方法，将本方法计算结果与ＧＢ５２６９—８５中的设计计算结果进行对比分析，得到满意的结果，说明本方法是有效的。     

轧机圆锥滚子轴承载荷的边界元法解析及实验研究

针对滚动轴承接触的特点,在轴承边界元法中采用赫兹接触理论对滚动体与轴承内、外圈的接触宽度进行修正。编制了三维有摩擦弹性接触的专用轴承边界元法计算程序,对轧机圆锥滚子轴承的载荷分布进行了数值模拟。采用轴承座直接测量法对轧机圆锥滚子轴承的径向和轴向载荷进行测试,并与数值模拟的结果进行了对比,实验测试结果与数值模拟的轴承载荷的分布规律基本一致,证明了边界元方法求解轴承载荷分布的正确性和有效性。     

对数修形圆锥滚子轴承接触副径向刚度分析

以Hertz弹性接触理论为基础,推导出对数修形圆锥滚子与滚道之间的接触变形公式,依据弹流润滑理论,建立对数修形圆锥滚子轴承滚子-滚道接触副等效刚度分析模型,通过实例对对数修形圆锥滚子轴承进行有限元静力学接触分析,得到滚子、滚道接触变形分布.结果发现:接触变形随滚子有效长度和等效曲率半径的增大而减小;等效接触刚度随着接触...     

汽车半轴楔横轧机辊系特性边界元法分析

在三维弹性接触边界元法基础上,根据半轴楔横轧机所采用双列圆锥滚子轴承的特点,开发了半轴楔横轧机滚动轴承边界元法专用计算程序,对汽车半轴楔横轧机辊系在不同结构下轴承载荷分布特性和辊系弹性变形特性进行较系统分析,找到了保证轴承载荷均匀分布和辊系挠度最小的最优辊系结构。研究结果为优化和设计汽车半轴楔横轧设备提供了有效的数值分析方法和理论依据。     

弹性复合圆柱滚子轴承静态径向刚度分析

从弹性复合滚子轴承的基本结构形式出发,结合当前关于实心圆柱滚子轴承和空心圆柱滚子轴承的研究方法,对弹性复合圆柱滚子轴承的静态径向刚度进行了深入细致的研究,用ABAQUS软件建立了弹性复合圆柱滚子轴承径向刚度的有限元计算模型,分析了填充度、外载荷、滚子数对径向刚度的影响规律,并和空心圆柱滚子轴承的刚度进行了比较。计算结果表明：填充度越小,随着外载荷的增大刚度的提升幅度越大,滚子数的增加对轴承的刚度提升幅度越大;填充度越大,随着外载荷的增大刚度的提升幅度越小,滚子数的增加对轴承的刚度提升幅度越小。弹性复合圆柱滚子轴承和空心圆柱滚子轴承比较时,填充度（空心度）越大,两者的刚度相差越大。     

Temperature rise of double-row tapered roller bearings analyzed with the thermal network method

Based on generalized Ohm׳s law, the thermal network model (TNM) is developed for double-row tapered roller bearing lubricated with grease, which is commonly used in high-speed railway. The load distribution and kinematic parameters in bearing are obtained by developing a quasi-static model. The temperature of bearing at different speeds, filling grease ratios and roller large end radius are investigated. The results show that large rotating speed and filling grease ratio result in high temperature rise, especially at roller large end/flange contacts. Besides, an optimal roller large end radius is presented and its mechanism has been explored.     

Analysis of heavy duty tilting-pad journal bearing taking into account pad distortion and possible adoption of rubber pad segments

In this work a comparative study has been made between the thermo-hydrodynamic performance of a three shoe tilting-pad journal bearing with rigid and elastic pads subjected to unbalance load. A case study of a bearing adopting three rubber pad segments has also been studied. The distortion of the elastic pad is introduced into the distribution of the film thickness through an iterative scheme to assess its effect on the load carrying capacity of the bearing. A finite element mesh is used to calculate the distortion of the elastic pad while a finite difference mesh is used to calculate the pressure field in the lubricant film. Results have shown a number of interesting conclusions regarding the adoption of rubber pad segments instead of tilting-pads. There is an increase in minimum oil film thickness when using elastic pad or even rubber pad segments compared with rigid pads. Also the maximum pressure and load carrying capacity are not significantly affected.     

刮板输送机系统机电耦合模型及仿真分析

根据刮板输送机机械系统与控制系统之间的耦合关系,推导出刮板输送机的非线性状态空间机电耦合方程,采用MATLAB/Simulink模块建立刮板输送机的仿真模型,对刮板输送机系统的机电耦合动力学问题进行仿真和研究;采用等效变化载荷质量分析刮板输送机在空载启动、平稳运行、载荷突增以及卡链工况下的刮板链速度、电磁转矩的特性曲线,得到了启动时两链轮的转角曲线。结果表明,驱动链轮与从动链轮启动时转角差约为85°,从动链轮启动旋转较驱动链轮滞后约0.8s。研究结果为研究刮板输送机不同工况、载荷下的转矩、速度变化以及计算链轮张紧度提供了理论和数值依据。