The wear volume and knowledge about wear processes occuring in the wheel-to-road contact are of critical importance to the development of new material and scheduling maintenance operations, such as grinding rail sections. To this end, wear tests were performed under various predefined parameters. A two roller model was selected as the testing principle by using the standard-quality materials R7 for die wheel roller and 900A for the rail roller. The maximum Hertzian pressure, the circumferential speed, the creep and the direction of loading were varied. The experimental examinations required a new test bench be designed and built. On the new test bench the normal load was applied by means of a novel supporting roller system. This design prevented misalignment of the test rollers to be a weak point of traditional test machines of this kind. The new test bench yielded a good reproducibility of results. The essential results are: 1) The wear volume increase proved to be proportional to the increase of the acting pressure and the creep between the test rollers. 2) Increasing the circumferential speed of the test rollers caused a reduction in the wear volume both at the driving and at the driven roller. 3) A significant wear reduction at the driven rail rollers could be achieved by periodically reversing the direction of the acting friction forces; under such reversing conditions of operation a change in the wear volume at the driving rollers manufactured from wheel material could not be detected. 4. At creep values of about 0.25% a change between low wear and high wear levels was found for the material combination of R7 (driving) against 900A (driven). 5.The driving roller and the driven roller differed fundamentally in their wear processes since their subsurface material layers are exposed to different stresses and, consequently, exhibit a different level of work-hardening. Hence, wear of the driving roller, which was exposed to lower stresses and exhibits a lower surface hardness compared to the driven roller was mainly caused by tribochemical reactions, whereas fatigue and abrasion were the marked wear-producing mechanisms at the driven roller. Examinations as to the extent to which theoretical results can be applied to practise, revealed a good correspondence between wear-specific friction work of the model and of a real system.
Friction and wear testing of rail and wheel material
2003
7 Seiten, 19 Bilder, 8 Quellen
Conference paper
English
Friction and wear testing of rail and wheel material
British Library Conference Proceedings | 2003
|Friction behaviour and wear properties of rail and wheel material
Tema Archive | 2003
|Tema Archive | 2003
|