ISSN   1004-0595

CN  62-1224/O4

高级检索

限量供油条件下微柱阵列束油表面润滑增效特性研究

Lubrication Enhancement by Micropillar Array Surface with Oil Capture under Limited Lubricant Supply

  • 摘要: 在润滑轨道两侧制备以防指纹油涂层(Anti-fingerprint coating, AFC)修饰的微柱阵列(Micropillar array, MA),形成润湿性梯度束油的润滑增效表面. 使用点接触光弹流润滑油膜测量仪测量了该表面在限量供油往复运动条件下的油膜厚度以及油池形态,探究了往复频率、束油轨道宽度和载荷对润滑性能的影响,同时与未经AFC修饰的微柱阵列束油表面和仅以AFC形成的束油表面进行了对比. 结果表明:制备的经AFC修饰的微柱阵列束油表面比其他2个束油表面有更好的润滑特性,往复运动条件(4 Hz)下明显改善了行程中点及两端点处的润滑状态,相对原始未处理表面行程中点处中心油膜厚度最高提升了51.4%. 表面在束油轨道宽度接近Hertz接触区宽度时集油效果最强,随着轨道宽度增加集油效果减弱. 载荷对微柱束油阵列表面的集油效果影响显著,随着载荷增大轨道机械分离作用变强、毛细回流作用减弱,造成集油能力和油膜厚度下降.

     

    Abstract: In the practice of lubrication, excessive lubricating oil is often proposed to be supplied to form higher film thickness and reduce the wear of contact pair in industry, which brings a series of problems such as the rise in oil temperature, resource waste and environmental pollution. With the continuous development of the concept of green lubrication, accurate and efficient lubrication with limited oil supply has attracted researchers’ attention and is becoming a new point in tribology research, which can change the problems brought by traditional oil supply approach. The purpose of limited lubrication is to improve the utilization efficiency of lubricant and ensure the lubricant supply of tribo-pairs. Inhibiting the spreading of lubricant on the surfaces of tribo-pairs or enhancing the replenishment of lubricants are critical to improve the performance of limited oil supply. People have proposed various strategies to achieve this purpose such as the use of surface texture, chemical coatings or assistant of physical structure. In this paper, a lubrication enhancement surface with oil capture capability was prepared through the formation of stepped wettability gradient, which was generated by the central oleophilic lubricating track and micropillar arrays (MA) with anti-fingerprint coating (AFC). The film thickness and shape of the oil pool on this fabricated surface under reciprocating motion were measured on a ball-on-disc test rig with limited oil supply. The influences of reciprocating frequency, width of lubricating track and applied load on the lubrication properties were investigated. Meanwhile, the lubrication performance of micro-pillar array surface without AFC modification and the surface only modified with AFC were studied. The results showed that the state of oil droplets on prepared AFC-modified micropillar array surface changes from Wenzel state to Cassie-Baxter state, thus it presented stronger oleophobic property and the lubricant oil gets mostly pinned on the lubricating track. Compared to the other two oil gathering surfaces, the micro-pillar array surface had a better lubrication performance. Through enhancing the replenishment of lubricants on both sides of lubricating track, the oil supply at the middle point of reciprocating stroke and two end points was obviously improved under the reciprocating motion (4 Hz), and the lubrication state gets improved with a higher film thickness. The measured central film thickness presented film thickness higher by up to 51.4% than the original surface. The experimental results showed that the oil replenishment was affected by the width of lubricating track. The oil collection capacity was the strongest when the central lubrication track width was close to the radius of the Hertz contact region. With the increase of the track width, the lubricant distribution on both sides of lubricant track became more dispersed, and the lubricating oil requires longer reflow time, resulting in smaller oil collection capacity of a micro-pillar array surface. The applied load presented significant influence on oil collection capacity of this new surface. Increase in load enhances mechanical separation of lubricant and deteriorates the capillary effect, resulting in the decrease of the oil collection capacity and then lower film thickness. This study provided a new approach for improving the oil replenishment under limited lubricant supply.

     

/

返回文章
返回