Analysis And Experimental Study On Heat Transfer Mechanism Of Graphene Lubricating Oil In High Speed Bearing

The core component of the machine tool is the motorized spindle.When the bearing is working,the heat generated by the friction between the inner and outer rings and the heat generated by the motor coil causes the bearing to deposit heat.Long-term overheating work will seriously affect the bearing life and the working accuracy of the motorized spindle.Over the past period of time,research on lubricants and greases have gradually decreased,and nanofluids have gradually attracted people's attention due to its great thermal conductivity.There is no relevant research on using graphene as a lubricant additive for heat transfer in the bearing cavity.When high-speed bearings are working,various working environments and processing will influence the quality of requirements.The thermophysical properties of the material itself and the stability during movement cannot meet the requirements,lead to failures and shortening in their life.Therefore,active control will be great significance to maintaining the dynamic stability of the motorized spindle,the use of an effective temperature rise prediction method to accurately predict the bearing temperature field is a prerequisite for the realization of active temperature rise control.Thermal conductivity is a measure of the ability of a substance to conduct heat.Accordingto molecular dynamics theory and thermal laws,a Graphene-GCr15 molecular dynamics model is established to analyze the number of layer,stacking methods,temperature and pressure on the thermal conductivity of Si₃N₄-GCr15 friction pairs.The results of simulation calculations show graphene can express great thermal conductivity.In a ferm of a single-layer graphene film,the ability to transfer heat is higher.As the improment of graphene film layers,the ability to transfer heat decreases.When the number of film layers reach four or five layers,the ability of transfering heat is relatively strong.Obviously,AAA stacking greatly improves the thermal conductivity of Irregular graphene sheets cumulatively change the thermal conductivity calculation results.The calculated value of ABA accumulated thermal conductivity is lower than the calculated value of AAA accumulated thermal conductivity at498K The thermal conductivity is higher than that under low temperature conditions;Relatively high ambient pressure calculates a high thermal conductivity value,and the thermal conductivity value at 0.4Mpa is higher than the thermal conductivity at low ambient pressure.The wear test results show that the graphene nanolayer can change the temperature change in the X direction of the contact area and improve heat transfer,and make the friction zone better thermally.This performance is more obvious at high temperatures.The bearing temperature rise test experiment analyzes the graphene affects the temperature structure of the bearing,and graphene nanofluids with different volume fractions and oil-air lubrication devices have different effects on the changes in bearing temperature rise.Most results show that adding a certain piece of graphene can import the lubricating oil capacity and conduct heat in the X direction of the friction pair.The situation has been greatly improved.The influence of the fluid add graphene value and the oil-air lubrication system value on the temperature rise of the bearing under the condition of gas-liquid-solid three-phase fluid is experimentally studied.Using orthogonal test method,comprehensive consideration of various parameters,the pressure of air entering the bearing is 0.36MPa?0.39MPa,the graphene concentration is0.075%?0.1%,and the oil supply interval is 1min?2min,which is a good range of bearing operating parameters.After the heat transfer coefficient is optimized,the absolute error of the temperature field prediction is 3.24?,and the prediction accuracy is improved by 10.8%.The results of this paper show that different forms of graphene express different thermal conductivity and change the temperature rise of the friction area;adding an appropriate amount of graphene nanofluid can reduce the temperature rise and deformation of the bearing.,providing a basis for bearings in actual use of the actual cooling and lubrication.