颗粒含量对液固二相流体润滑特性影响的试验研究

利用自制的活塞环-缸套摩擦磨损试验台,基于实验探讨了固体颗粒含量对液固二相流体润滑特性的影响。液固二相润滑剂是由纯油和质量分数为0、0.1%、0.5%、1%、2%、5%的MoS2颗粒混合而成的。试验过程中在线测量了摩擦副表面本体温度和摩擦力,并测试试验前后缸套表面的表面形貌和磨损量。结果表明,在颗粒质量分数大于0.5%后,系统的摩擦力、表面本体温度、磨损量均有不同程度的改善,1.5μm粒径的MoS2颗粒的最佳添加量约为2%。     

一种基于力觉的机器人对孔装配方法

针对带电作业机器人更换金属氧化物避雷器过程中精确对孔装配的需要,提出一种基于力觉自主控制机器人在绝缘横担上寻孔并装配避雷器的方法。控制过程中针对避雷器下端头的特殊形状以及电杆绝缘横担的作业场景,在机器人末端加装力觉传感器,将转换后的力作为被控量,设计一种由触担、寻孔、渐入和插入四个过程构成的对孔装配策略,使机器人能够将避雷器的下端头准确地插入横担上的安装孔。试验结果验证了所提方法的有效性。     

机械维修性的数量特征

维修性是机械设备的一个重要特性。就其数学模型、维修时间的分布与参数、维修周期的确定及维修性分配等问题进行定量分析 ,以便更合理地进行机械设备维修决策和设计     

Development of in situ system to monitor the machining process using a piezo load cell

The measurement of cutting force is one of the most frequently used techniques for monitoring machining processes. Its widespread application ranges from tool condition identification, feedback control and cutting system design to process optimization.This paper suggests another system for measuring cutting force in milling processes. Generally, tool dynamometers are taken into account for the most appropriate cutting force measuring tool in the analysis of a cutting mechanism. However, high prices and limited working space make in situ systems difficult for a controllable milling process. Although an alternative suggestion is to use an AC current from a servomotor, it is unsuitable for cutting force monitoring because of a small upper frequency limit and noise.The suggested cutting force measuring system is composed of two piezo load cells placed between the moving table bracket and the nut flange of the ball screw. It has many advantages, such as lower cost and a wider measurement range than the tool dynamometer, over using the built-in feeding system and the low-cost piezo load cell for applying a conventional machining center.This paper focuses on the performance test of a newly developed measuring system. By comparing the cutting force between the tool dynamometer and the system developed from a series of end milling experiments, the accuracy of the cutting force measurement system was verified. Linearity, transverse sensitivity and the upper frequency limit of the system were verified by experiment.     

Cutting Force Model for a Small-diameter Helical Milling Cutter

In the milling process, the major flank wear land area (two-dimensional measurement for the wear) of a small-diameter milling cutter, as wear standard, can reflect actual changes of the wear land of the cutter. By analyzing the wearing characteristics of the cutter, a cutting force model based on the major flank wear land area is established. Characteristic parameters such as pressure parameter and friction parameter are calculated by substituting tested data into their corresponding equations. The cutting force model for the helical milling cutter is validated by experiments. The computational and experimental results show that the cutting force model is almost consistent with the actual cutting conditions. Thus, the cutting force model established in the research can provide a theoretical foundation for monitoring the condition of a milling process that uses a small-diameter helical milling cutter.     

SiCp/Cu复合材料切削加工性及其加工表面微观结构研究

通过应变测力仪，测量每一组切削用量参数下Cu及SiCp／Cu复合材料的切削力，并用电子显微镜观察分析切削表面的微观结构。研究表明：由于SiC颗粒对位错运动的阻碍，在SiCp／Cu界面处形成位错塞集群，产生应力集中，使SiCp／Cu复合材料切削过程呈典型的脆性分离；切削力随背吃刀量和进给量的增大而增大，随切削速度的增大而减小。     

"多点应力法"测量多级离心泵轴向力和径向力

提出了用“多点压力法”测量多级离心泵轴向力和径向力，在泵轴向空间无法安装外接测量装置时解决了测量问题。利用测量的数据，可靠地修正了原有平衡鼓的外径，结果表明该方法简便，精确，能降低测量成本，缩短测量时间。     

蒙特卡洛法在确定应力分布时的应用

根据蒙特卡洛法和有关应力的理论，在Visual c 6．0的环境下开发了蒙特卡洛法确定应力分布的通用程序。     

冷拉伸滚压成形新工艺参数研究

采用ADINA有限元软件对高强度柔性螺栓在此加工工艺中定义材料性能,建立滚压模型,划分网格,约束边界条件,施加载荷.对在不同拉力,滚压量两个实验参数下进行冷拉伸滚压新工艺加工模拟仿真,得到端面中点的最大应力,有效应力及位移与时间函数的图形,并分析结果得出最有利于加工的工艺参数.为下一步做轴类冷拉伸滚压成形实验提供重要的实验参数.     

行人大腿冲击器的生物仿真度

针对汽车行人保护碰撞试验中大腿冲击器的生物力学特性问题,采用THUMS(total human model for safety)人体模型与大腿冲击器进行对比仿真分析.模拟THUMS-SUV行人交通事故,并对THUMS人体模型大腿所受冲击力和弯矩进行了输出.根据事故中行人大腿初始碰撞条件和行人大腿最低能量状态,分别建立两种工况的行人大腿冲击器碰撞模型并进行模拟,对比分析行人大腿冲击器和THUMS人体模型大腿的动态响应、最大瞬间冲击力和最大弯矩.仿真结果表明:相对THUMS人体模型而言,大腿冲击器的最大瞬间冲击力偏高而最大弯矩偏低,行人小腿和上身的运动和接触作用,会影响大腿部位的接触力和最大弯矩,因此大腿冲击器的生物仿真度有待提高.