Experimental Investigation On Friction And Wear Properties Of Textured Port Plate

As an important hydraulic power component, the axial piston pump which in plain flowdistribution form plays a center role in many areas. It is widely used in not only the large engineeringmachineries but also aviation and spaceflight transport, water projects and others. With thedevelopment trends of high pressure, high rotating speed and high flow, the wear and burnphenomenon in each friction pair of the axial piston pump is increasing, especially on the port platepair which is much easier to be worn out, and this phenomenon restricts the operation life anddevelopment of piston pumps directly. As a consequence, designing the friction pairs reasonably andimproving the lubrication conditions are significant for the development of piston pumps.Surface texturing, which has been proven to be an efficient technical means to improve thetribological properties of friction pairs, is the technology to fabricate micro pattern with certain arrayand dimension on the surface by physical or chemical methods. In recent decades, it has beenattracting increasingly attention of domestic and foreign researchers for its excellent performances,and successfully applied in different fields such as mechanical seal, cutting tool, cold forging die, andso on. These examples provide the foundation for the application of surface texture on axial pistonpump, which has positive significance for the improvement of tribological performances of the portplate.The photolithography and micro electrochemical machining were employed to fabricate themicro-dimples with different geometric parameters on the valve plate. The tribological experimentswere carried out on the port plate pair’s wear tester under simulating operating conditions to studyhow the surface texture influenced the friction and wear performances of port plate pair in differentconditions. The friction coefficient, wear loss and wear appearance were taken to be the evaluatingindex.The conclusions of this study showed as follows:1. Compared with the untextured port plate pair, the micro-dimples with appropriate geometricparameters can reduce the friction coefficient effectively and improve its lubrication condition.Micro-dimples with different parameters showed the better results of friction reduction under highercontact pressure(1.80MPa). In addition, the diameter and area ratio were the important factors toeffect the tribological properties of port plate pair, when the diameter is100μm and the area ratio is10%, the largest friction reduction ratio is44.0%. 2. Surface texture can have a stable friction reduction in long-term experiments.3. The wear condition can also be improved by surface texture which mainly reflected in thewear loss and surface roughness. The better wear reducing effect was obtained when the diameters ofmicro-dimples were larger, and under the experimental condition, the wear loss of textured port platepairs with diameter range from100μm to300μm were only about4.54%~7.14%of that of untexturedones.4. The analysis about wear appearance of the upper and lower specimens shows that, texturedport plate pairs can avoid adhesive wear in different degree, which is formed on the untextured ones.Further analysis of lower specimens reveals that containing solid particles is one of the main reasonsto improve tribological performance of port plate pairs.5. There exists a good correlation between friction and wear, so reducing the friction properlycan be conducive to the reduction of wear.