轿车后轮轴承磨粒磨损失效特性与产生机理

通过对 2 0 0余套早期失效的轿车后轮轴承失效统计分析发现 ,磨粒磨损及烧伤是后轮轴承主要的失效形式 ,该失效形式占所有轴承失效率的 6 0 %。根据轿车后桥半轴的结构、后轮轴承装配状况、及轿车后轮的动力学特性 ,本文提出了轿车后轮发生磨粒磨损及烧伤损坏的失效模型 :(1)在惯性载荷作用下 ,轴承内圈与轴颈接触部位的切向蠕动形成粘着磨损颗粒 ;(2 )半轴轴端螺纹防松键槽侵入轴颈与轴承内孔配合段 ,导致键槽锐边在轴承内孔刮研 ,产生切削微屑 ;(3)蠕动及刮研作用产生的磨损颗粒进入轴承滚道表面 ,与滚动体形成三体磨粒磨损。(4)在制动鼓的维修过程中 ,磨损颗粒的异常侵入 ,同样会导致轴承发生磨粒磨损失效。本文提出 ,防止轿车后轮轴承发生早期磨粒磨损失效的有效途径是 :(1)尽量避免与轴承配合的轴颈圆柱表面受到结构或工艺性的损害。(2 )提高轴颈与轴承内孔表面的光洁度和配合精度 ,以降低蠕动造成的磨损颗粒大小和数量。(3)通过密封等防范措施 ,防止磨损颗粒的侵入。

On Abrasive Wear Mechanism of Automobile Rear-wheel Bearings

Failure characteristics of automobile rear wheel bearings are investigated in this paper. Analyses show that the abrasive wear dominates the failure forms with a high percentage of 60%. By analyzing the structure of rear axle, bearing settings, and the rear wheel dynamics, a failure mechanism model is presented as follows: (1) The creep between inner ring and the fixed rear axle journal, due to the shift of contacting center under the action of inertia dynamic load, will result in adhesive wear particles. (2) The sharp edges of the slot, which is processed on the rear axle for anti loosening of the lock nut, will scrape the bearing bore surface, bringing about small chips and particles. (3) When the abrasive particles from creeping and scraping enter the bearing raceway, three body abrasion will take place among contacting elements. (4) The abrasive wear can also be stimulated when the wear particles from the contacting areas of the break drum enter the bearing during drum maintenance. It is suggested that the cylindrical parts of the axle fitting with the bearing should not be damaged for any reason, and the surface finish and the fitting accuracy of the journal and bearing bores should be enhanced to avoid both abrasive wear and locally concentrated fatigue wear of rear wheel bearings.