Study On Wear State Of Main Bearing Friction Pair Of Marine Diesel Engine

Ship transport plays an important role in the national trade.About 80% of ships are powered by diesel engines.However,vicious accidents due to the failuer of ship power plant occur all around the world,which lead to terrible economic losses and major casualties.The main bearing of the diesel engine suffer the most from operation friction and afford significant load during working process because of the sliding bearing structure and the majority of engine failure cases are resulted from poor lubrication.Therefore,high quanity lubrication is required.Usually,Marine diesel engine operates in a special condition that lubrication oil would be polluted by water or particle,which contributes to the condition that main bearing becomes tear even the phenomenon.The potential damage that water pollution cases to bearing may not immediately reveal.Thus,to study the abnormal wear law of the bearing when the oil is contaminated with water becomes very urgent in recent years.The simulation of friction pair processes that are determined by different contend of water introduced to lubrication oil have been carried out from pin friction and wear testing machine.During this simulation,various surfaces and abrasive grain of wear stage are analyzed,which includes spectral analysis,iron spectrum analysis according to the comparison from the different parameters of abrasive grain type,metal concentration,abrasive concentration,abrasive size,the abnormal friction law has been found.The results show that few content of water contribute to the lubrication of deputy friction.With the improvement of water content,the quanity of lubrication oil decreases and leads to more serious wear.Refering to the experiment ot friction and wear,several analysis have been worked out in different process,which contributes to a new way to research the impacts from mixed lubrication oil.The characteristics of abrasive grains in the test process were analyzed by using iron spectroscopy,spectroscopy and image processing technology combined with pyrometer,atomic emission spectrometer and Keyence super-depth microscope.The surface roughness of the friction surface was measured by surface contact profiler.The reasoning reasoning method based on evidence reasoning is used to digitize the wear degree of marine diesel engine.This method can use the qualitative information such as expert experience at the same time,and can also use the operation data and historical data of the diesel engine to train the initial model based on the expert experience to improve the diagnostic accuracy and applicability of the model.