不同接触参数下车轮多边形形成及发展试验研究

Experimental Study on the Formation and Evolution of Wheel Polygon under Different Contact Parameters

利用WR-1轮轨滚动磨损试验机研究了不同轮轨接触参数(垂向力、蠕滑率、转速)下车轮多边形形成规律,分析了滚动过程中的轮轨振动特性,探索了多边形车轮试样的硬化与损伤规律。结果表明:当垂向力、蠕滑率和转速较小时,轮轨系统振动稳定,车轮试样不产生多边形;随垂向力、蠕滑率和转速增大,系统激发了明显的主振动频率,振动幅值随运行时间不断增大,车轮多边形逐渐产生;且多边形波深随垂向力和蠕滑率增大呈现增大趋势。试验后,车轮试样硬度随深度逐渐降低,未产生多边形的车轮试样硬度在圆周方向上无明显波动,多边形车轮试样硬度随轮廓变化而变化,波峰区域硬度低、波谷区域硬度高,波谷区域塑性变形层厚度明显大于波峰区域。多边形车轮试样波谷区域与未产生多边形车轮试样损伤均以疲劳磨损为主,波峰区域表面存在大量剥落坑,波峰与波谷处裂纹长度与深度相较于无多边形车轮试样都明显减小、裂纹角度显著增大。多边形车轮试样表面会受到反复的轮轨冲击-挤压作用,垂向力与蠕滑率的增加会使冲击-挤压作用更加剧烈,车轮多边形更加严重。研究结果对进一步了解车轮多边形形成机理及抑制措施提供一定的指导意义。

The wheel polygon formation rule under different wheel/rail contact parameters(normal force,slip ratio,rotational speed)is studied using the WR-1 wheel/rail rolling wear machine.The wheel/rail vibration characteristics during the rolling process is analyzed,and the hardening and damage rule of polygon wheel samples are explored.The results show that when the normal force,slip ratio and rotational speed are small,the wheel-rail vibration is stable and the no obvious polygon is produced on the wheel sample.With the increase in normal force,slip ratio and rotational speed,the obvious main vibration frequency is generated,and the vibration amplitude increase with the time.The polygon is generate gradually on the wheel samples.The polygonal wave depth increase with increasing the normal force and slip ratio.After the test,the hardness of the wheel sample decreased gradually with the depth,and the hardness of the wheel sample without polygon had no obvious fluctuation in the peripheral direction.The hardness of the polygon wheel sample changed with the profile.The hardness of the crest region is low,but the hardness of the trough region is high,and the thickness of the plastic deformation layer in the trough region is obviously greater than that in the crest region.Fatigue wear was the main damage of the trough region of polygonal wheel samples and non-polygonal wheel samples,and there are a large number of spalling pits on the surface of the crest region.The length and depth of the cracks at the crest and trough are significantly reduced and the crack angle is significantly increased compared with the non-polygonal wheel samples.The surface of polygonal wheel samples could be subjected to repeated wheel-rail impact-crushing actions,and the increase in normal force and slip ratio could make the impact-crushing actions more severe and the polygon of wheel more serious.The results could provide guidance for further understanding the mechanism of wheel polygon formation and the suppression measures.