Tribological Behavior And Seizure Failure Analysis Of Bimetallic Piston Pair

Because of its compact structure,high output pressure per unit volume and low cost,swash plate axial piston pump is widely used in mechanical equipment,military and aerospace fields.However,with the development of mechanical equipment in the direction of high pressure,high temperature and high load,the service life and reliability of the piston pump has been put forward higher requirements.At present,the high pressure piston pump still relies on foreign imports,and the fundamental reason is that the friction and wear mechanism of key friction pairs are not thoroughly studied.Therefore,it is of great significance to study the friction and wear performance of piston pump under extreme working conditions for improving the wear resistance and service life of piston pump.In this paper,the piston pair of swash plate axial piston pump is taken as the research object,and the friction and wear performance and anti-seizure performance of piston pair cylinder material under boundary/mixed lubrication condition are studied in detail.The main contents are as follows:（1）Based on the mechanical properties and motion rules of the piston pair of a piston pump,the key parameters for three limiting conditions,namely,the maximum specific pressure,the maximum specific work,and the maximum linear speed,of the contact between the piston and the piston hole,were obtained.The tribological study of the cylinder material of the piston pair was conducted using the"ring block"and"shaft sleeve"friction models,and the experimental plan was developed.（2）The test process was simulated and analyzed by finite element simulation software before the test,and the stress and strain distribution and temperature change on the contact surface during the friction and wear process were observed,which provided reference and guidance for the subsequent test research.（3）Four kinds of copper-based alloy composites,Cu Sn10Bi3,Cu Sn10Bi3Mo Si₂1,Cu Sn10Bi3Fe_mP_n1,Cu Sn10Bi3Mo Si₂&Fe_mP_n1,with different hard particles were prepared by powder metallurgy technology,and the influence of hard particles on the metallographic structure of copper-based alloy was observed.The friction and wear properties of four kinds of samples under three extreme working conditions of boundary/mixed lubrication state and dry friction were tested by using"ring-block"testing machine.The surface morphology and element composition of worn surfaces and debris were characterized and analyzed.And the friction and wear mechanism of piston cylinder liner material under starved lubrication was obtained.（4）The"ring block"testing machine and the"shaft sleeve"testing machine were used to test the anti-seizure performance of different contact modes（i.e.,conformal contact and non-conformal contact）in the piston pair.Analyze the surface wear morphology after seizure,explore the influence of adding different hard particles on the seizure factors of piston cylinder material,and get its seizure failure mechanism.In summary,the equivalent stress and equivalent elastic strain on the surface of copper layer increase with the increasing load,during the friction process,and the maximum equivalent stress occurs at the joint of copper layer and steel plate.The test results show that the addition of different hard particles can effectively improve the metallographic structure of copper-based alloy composites,and the friction and wear properties and anti-seizure properties under extreme working conditions are greatly improved,providing a certain theoretical basis and experimental guidance for the research and development of piston pump.