地铁钢铝复合式第三轨/受电靴载流摩擦磨损特性研究

Tribological Characteristics between Third Rail and Collector Shoe under Electric Current

通过对销-盘摩擦磨损试验机的夹具和控制部分进行改进,研制出载流摩擦磨损试验装置,并采用该装置研究了地铁钢铝复合式第三轨与受电靴摩擦副之间的载流摩擦磨损特性,采用激光三维共焦扫描显微镜和电子能谱仪等微观手段,结合电接触理论分析了摩擦副的载流摩擦磨损机制.结果表明:存在1个法向压应力阈值,当试验的法向压应力大于此阈值时,摩擦系数随着电流的增加而增大,此时电流增加了机械磨损;而当法向压应力小于此阈值时,摩擦系数随着电流的增加而减小,此时电弧烧蚀材料损失量较机械磨损大;钢铝复合式第三轨的主要磨损机制为粘着磨损和磨粒磨损;钢铝复合式第三轨授流时,在一定的列车运行速度下法向压应力阈值是最佳的工作压应力,既能保证顺利授流,又使得摩擦副材料的磨损量较小,确保行车安全,降低维护频率,节约地铁运行成本.

A new test rig was developed by modifying the clamps and the control system of conventional pin-on-disc tester. The friction and wear characteristics of aluminum-stainless steel composite conductor rail and collector shoe used in metro power supply were investigated on the rig with an electrical current applied across the sliding interface. The morphologies of worn surfaces were observed and analyzed by means of laser confocal scanning microscope and energy dispersive x-ray spectroscopy. Wear mechanisms with electric current were analyzed and discussed based on electric contact theory. Experiment results show that a threshold value of normal stress exists in friction and wear with the variation of electric current. If normal stress is larger than the threshold value, friction coefficients increase with the increasing of electric current, and current enhances mechanical wear. If normal stress is smaller than the threshold induces electric arc erosion. value, friction coefficients decrease with the increasing of electric current, and current Wear mechanisms of the part with current are dominated by adhesive and abrasive wear, but the material volume loss caused by electric arc erosion is much larger than it caused by mechanical wear. For a certain velocity, the threshold value of normal stress is an optimum normal stress, which makes not only electrical power supply stable but also mechanical wear lower and railway running cost saved.