Effect Of Operating Parameters On The Performance Of Rolling Bear Under Oil-air Lubrication

With rotating machinery advancing toward more high speed,some breakthrough is needed in the maximum speed of rolling–element bearings as a “joint” of machines.Unfortunately,traditional grease lubrication and oil lubrication cannot satisfy the requirements of bearings with higher and higher running speeds.Instead,air-oil lubrication as a new lubrication method has being been employed in mechanical industry.This new lubrication approach is featured with increase in the operation speed and extended service life of a rotating machinery as well as its environment friendly and running efficiency.For the best performance,different working parameters have to be determined of an air-oil lubrication system according to its running conditions.Furthermore,reasonable design of the elements,such as the nozzle structure,its location and the length of the pipe,are important to improve the lubrication.In this project a new version of the rolling-element bearings chamber has been finished with air-oil lubrication,which is now incorporated into the bearing test rig in the lab to carry out experiments to get optimal working parameters for the guide bearings of the steel rod milling lines in Qingdao Special Iron & Steel Co.,Ltd..Some researches have also been completed to investigate a new type of nozzle proposed by our group.In addition,CFD simulation of the bearing internal space was finish using FLUENT software.The main work is as follows:(1)The old bearing chamber has been updated of the bearing test rig,which enables more adaptive connections among the nozzle,the loading head and temperature measuring system.(2)After a field survey of the guide bearing working conditions of steel rod milling lines in the Qingdao Special Iron and Steel Co.,Ltd.,experimental study of the oil-air lubrication parameters was carried out by our bearing test rig,which has provided helpful data support to the company.The main parameters include tube length,axial pre-load,the number of nozzles,air pressure,speeds and oil-supply quantity.(3)A new type of spray nozzle,which was proposed in our group recently,was studied by three test schemes.Its advantages have been validated including reduction of oil supply fluctuations,improvement of oil supply efficiency and energy conservation.The structure parameters and surface tension coating for the guide fibers have also been studied to investigate their influences on the oil supply,which provides basic data for the further nozzle improvement.(4)Using FLUENT software simulation the thermal field of the internal space of a b earing was calculated and the influence of the rotating speed and air-oil inlet speed on the temperature rise has been investigated.Finally lubrication characteristics provided by the oil-air and lubrication jet were compared.