干摩擦条件下聚甲醛塑料动力齿轮传动啮合效率的分析研究与计算

从高分子材料的粘弹性力学模型出发，推导出塑料与钢齿轮副粘滞发热损耗功率的计算公式，并以此为基础，结合塑料材料的弹性模量和滑动摩擦系数的测试数据，考虑温度、弹性模量、摩擦系数及载荷之间复杂的偶合关系，研究并提出了一种在干摩擦条件下塑料与钢齿轮副啮合效率的数值计算方法，运用这种方法，可以方便地获得任意啮合位置的瞬时啮合效率及一个啮合循环中的平均啮合效率，通过对聚甲醛与４５＾＃钢齿轮副的计算发现，在干摩     

Thermo-Mechanical Model and Thermal Analysis of Hollow Cylinder Planetary Roller Screw Mechanism

Planetary roller screw mechanism (PRSM) is widely used for rapid and precise motion translation from rotary into linear motion due to its high stiffness and high position accuracy. However, a high speed PRSM drive system naturally generates significant amount of frictional heat at the contact interfaces, which causes thermal deformation and thermal error and reduces motion accuracy. Preload is usually applied to remove the axial backlash of the PRSM for achieving high accuracy and great stiffness. However, more frictional heat is produced by such preload. On the other hand, larger numbers of angular contact bearings are needed to support the heavy axial load. The friction heat generated in support bearings has also to be investigated. In order to estimate the thermal distribution and thermal error of the hollow cylinder PRSM, a thermo-mechanical model based on finite element method (FEM) is developed, where heat generation from the two main sources of the PRSM, the parameters calculation of heat transfer coefficient and other thermal boundary conditions were studied. The presented model is proven capable of investigating temperature distribution, thermal error, and cooling performances of coolants of the PRSM system.     

A Frictional Heat Model of Planetary Roller Screw Mechanism Considering Load Distribution

Planetary roller screw (PRS), with higher thrust, higher load capacity, and higher speed, is the best choice of the transmission component of the servo system. However, spinning sliding of rollers and support bearings can cause frictional moments and frictional heat, which is an undesirable phenomenon. Besides, frictional heat will further result in high temperature that causes deterioration of lubrication and eventually lead to destruction of the mechanism. Therefore, it is important to predict frictional moments which result in frictional heat. In order to predict the magnitude of frictional heat of PRS mechanism and study the influence of structural parameters of thread and operating conditions on frictional heat, first, a frictional moment model of bearings is built, and frictional moments models of PRS considering the elastic hysteresis of material, the spinning sliding of the rollers, the viscosity of lubricating oil and the differential sliding of thread raceways are established in this paper, respectively. Second, heat generation models of bearing and PRS are presented, respectively. Finally, relationships between frictional heat in terms of operating conditions of PRS, contact angle, and helix angle of roller thread are investigated. The achievements of this project will provide theoretical basis for the design of PRS with lower frictional moments and higher transmission efficiency.     

带有摩擦耗能元件的框架结构动力分析

本文提出粘性屈服模型来模拟摩擦耗能元件的力-速度关系,该模型是连续变化的,克服了库仑摩擦模型不连续导致数值计算复杂的缺点,在进行摩擦耗能体系的动力分析中,采用缩减自由度技术,并作适当的变换,则带有摩擦耗能元件体系的动力分析归结为求解微分代数方程,本文采用增量型Rosenbrock二级三阶半隐式Runge-Kutta法求解该方程,以考虑框架和支撑的材料和几何非线性。对带有摩擦耗能元件的钢框架进行了弹塑性动力分析,研究了支撑刚度与结构层刚度的比值、摩擦力的大小以及地震波类型等参数对体系的影响。     

直流磁场下销盘摩擦过程中的电磁感应力矩分析

为了研究磁场对材料摩擦磨损性能的影响,本文分析了直流磁场下销盘摩擦过程中的涡流和电磁感应力,并通过积分得到感应力矩的计算公式.在销盘0.1 mm间隙时检测了磁吸力和在不同试验条件下盘试样所受的感应力矩,利用试验数据对感应力矩公式中的修正系数进行了最小二乘法拟合,所得感应力矩公式的计算结果与不同电流和转速下的试验数据很好地吻合.在摩擦磨损过程中,可利用感应力矩公式计算出相应试验条件下盘所受的感应力矩,分析其对摩擦系数的影响.     

C7046112轴承摩擦力矩的研究

本文在大气条件下就不同轴向载荷、转速和润滑剂对C_(7046112)轴承摩擦力矩的影响进行了研究。结果表明,轴承的轴向载荷与摩擦力矩之间不是单调上升的函数,而是呈周期性变化的关系。文章指出,在选择轴承优化参数时必须综合考虑,而不能一味地追求摩擦力矩越小越好。     

山地输电线动刚度计算及模态分析

为了揭示地形变化对连续档输电线动态特性的影响，本文提出了基于任意高差角的动刚度理论．首先将单档导线视为连续档导线的子结构，构建了两悬挂点不等高的单档导线振动方程，并在该理论方程中引入了二次项，能够考虑重力沿弦向分量的影响，推导出绝缘子串绕其悬挂点转动的动刚度计算方法，通过动刚度理论研究连续档导线横向振动模态和频率，并应用有限元软件ABAQUS 验证理论模态和频率公式的准确性．所得结果表明，动刚度的计算方法具有较高的精度，理论模态与有限元输出结果吻合较好，同时获得的频率和模态可为山地高压输电线路防舞技术的研究提供依据．     

大型球轴承摩擦力矩试验台的研制及其实用性能的试验研究

为了研究大型轴承的摩擦性能，研制了一种可以测量外径２００～１５００ｍｍ球轴承的启动力矩、运转平均力矩、最大力矩和力矩变化幅值的大型轴承摩擦力矩试验台．这种试验台可以模拟轴承的启动角加速度、转动速度、预负荷和轴向工作负荷等．在此试验台上，对大型角接触球轴承成对预紧时的摩擦力矩与预紧量之间的关系进行了试验研究，并且根据试验结果，提出了一种适用于轴承外径２００～５００ｍｍ，转动速度低于３０ｒ／ｍｉｎ时计算摩擦力矩的经验公式．     

摩托车传动用滚子链磨损特性的研究

道路行驶磨损试验结果表明，摩托车传动用滚子链套筒和销轴零件的主要磨损形式是磨粒磨损，并伴随有疲劳磨损的特征．由微观分析和链条的磨损伸长量可知：套筒和销轴的初始表面硬度较高，有利于改善其磨损表面形貌状态和耐磨性；在磨粒磨损机制下，套筒和销轴零件的表面硬度较低，容易产生“犁切”，表面层的循环硬化现象比较明显，磨损严重；在油池润滑条件下，套筒和销轴零件的表面硬度较高，裂纹的扩展速率较快，循环软化现象也较明显，当表面硬度较低时发生循环硬化．循环软化与循环硬化是导致磨损严重的原因之一．     

GM-3摩擦衬垫动态滑移过程中的摩擦机理研究

采用GM-3摩擦衬垫与高强度透明钢化玻璃为摩擦副,在Rtec摩擦磨损试验机上进行往复滑动摩擦试验,使用高速显微摄像仪(VW9000)对接触摩擦界面进行实时原位观测,并利用灰度法计算接触界面的实际接触面积,探究GM-3摩擦衬垫的磨损机理.结果表明:GM-3摩擦衬垫的摩擦系数与实际接触面积呈正相关关系;其初期磨损机理主要为磨粒磨损和黏着磨损,后期为疲劳磨损和黏着磨损;初期磨粒磨损会导致摩擦系数增加;卷筒状磨屑生成过程中摩擦系数变大,随后细小的磨屑聚集尺寸变大,数量变少,摩擦系数趋于稳定.     

滚齿切削力矩的测试及其分析

本文介绍一用于测试滚齿切削力矩的测试系统,该系统开发利用８０９８单片机数据采集技术,并结合电压频率转换技术和光电耦合,实现了信号的无接触传输。应用该测试系统,作者实验分析了滚齿切削过程力矩的基本变化规律,并对滚齿过程的力矩变化作了定性和定量分析,为进一步探讨滚齿切削规律提供了有利的实验依据