复杂运行环境下高速轮轨最佳撒砂增黏策略试验

在车轮-钢轨高速接触疲劳试验机上开展水、油和树叶等污染下的高速低黏着和增黏试验,通过最高速度200km·h-1的对滚试验,测得不同第三介质条件下的轮轨黏着-蠕滑特性曲线,研究增黏砂粒径和撒砂量对增黏效果的影响。结果表明:喷撒增黏砂可有效恢复各种污染下的轮轨黏着水平,使200km·h-1下轮轨黏着系数保持在0.18以上,低速下更高;增黏砂粒径在0.4~1.0mm范围内增大或撒砂量在40~100g·min-1范围内增加时,增黏效果均稍稍增强,综合考虑确定试验机的最佳撒砂量为40g·min-1、最佳粒径为0.85~1.0mm;考虑试验机与现场轮轨系统的尺寸差异、运行时复杂气流所致砂粒损失及适当冗余度等因素,建议现场最佳撒砂量为115~175g·min-1、最佳粒径为1.0~2.0mm;喷撒增黏砂会造成车轮接触表面的麻坑损伤,也是造成现场车轮踏面常见麻坑损伤的根本原因。

Experimental Study on Optimum Sanding and Adhesion Enhancement Strantegy for High Speed Wheel and Rail under Complicated Operation Environments

A high speed test rig for rolling contact fatigue was employed to examine the wheel-rail low adhesion and enhancement in the presence of water,oil,leaves and so on.Through the rolling tests with the highest speed of 200 km·h-1,the adhesion-creep characteristic curves of wheel and rail under different third medium conditions were obtained,and the effects of sand sizes and sanding amount on adhesion enhancement were studied.Test results show that sanding can restore the adhesion level of wheel and rail effectively in the presence of all contaminants,and the adhesion coefficient can be kept above 0.18 at 200 km·h-1,which is higher at low speed.The effects of adhesion enhancement are slightly increased as the size of sand increases from 0.4 to 1.0 mm or the sanding amount increases from 40 to 100 g·min-1.Taking into account more factors,the optimum sanding amount and particle size are determined to be 40 g·min-1 and 0.85~1.0 mm for the test rig,respectively.Considering such factors as the size difference between the test rig and the on-site wheel-rail system,possible sand loss caused by the complex air flow during operation and the appropriate redundancy,the optimum sanding amount of 115~175 g·min-1 and optimum particle size of 1.0~2.0 mm on site are proposed.Sanding will cause pockmarks on the contact surfaces of wheels,which is also the root cause for the common pockmark damage on the wheel tread on site.