Experimental Study On Tribological Properties Of Tin Bronze Bushing And Numerical Simulation Of Wear Quantity

The connecting rod small head and piston pin in diesel engine are connected by connecting rod bushing,which forms friction pair with piston pin.The working environment is bad and serious wear will threaten the service life of diesel engine.It is important to study the tribological properties of connecting rod bushing for improving the service life of bushing and the reliability of diesel engine.The tribological properties of tin bronze are analyzed by means of experiment and numerical simulation.The main results are as follows:(1)The single factor test and mixed uniform design test of QSn7-0.2/40 Cr specimen were designed in the pin-disc test.The effects of single factors such as load,rotation speed,temperature and viscosity of lubricating oil on the test results are studied.The wear mechanism is also discussed.The results show that: in the single factor test,The wear mechanism of friction pairs is different under different test conditions.There may be many wear types such as abrasive wear adhesive wear and oxidation wear under the same test conditions.The effects of load,rotation speed,temperature,friction time and pairwise interaction on the wear capacity of friction pairs were studied in the mixed uniform design experiment.The mathematical model of wear capacity was analyzed by stepwise regression analysis.The results show that the interaction of load and temperature and the interaction of rotational speed and temperature and the change of temperature have great influence on the wear rate.When the load is 23 N,the rotational speed is 275 r / min,the temperature is 50?and the time is 30 min,the minimum wear capacity is 0.00001218 g.(2)Single factor test and orthogonal test were designed in the tribological test of tin bronze QSn7-0.2)bushing.The effects of load,rotational speed and matching clearance on the wear rate of the bushing were studied.Through variance analysis and response surface analysis,the effects of various factors and their interaction on wear quantity are analyzed,and the process parameters are optimized,and the mathematical model of wear quantity is established.The wear of connecting rod bushing is greatly affected by speed and fit clearance,load and clearance in interaction,and load and speed.The optimum results of wear response surface of the bushing are as follows: when the load is taken at 110 KN,the rotational speed is 230 r / min,and the matching gap is 0.14 mm,the wear capacity of the connecting rod bushing is 0.0054 mm.(3)A pin-disc wear simulation model is established.The wear coefficient is obtained by calculating the wear rate under different pressures in the pin-disc single factor test.The wear coefficient is involved in the analysis of wear quantity in the subroutine UMESHMOTION.The deformation area mesh is redrawn and the displacement field is updated,and the wear amount of the pin disk under different loads is simulated and analyzed,and the results are compared with the experimental results.The reliability of the pin-disc wear simulation model and the accuracy of the simulation results are verified.