| In this study,the influence of working conditions and grease cone penetration on the elastohydrodynamic(EHD)friction behaviours of grease with high shear rate was studied by using a Mini-Traction Machine(MTM)and changing single variable under the condition of sufficient grease supply.The microstructure and composition of the grease were analyzed by metallographic microscope and infrared spectrum,and the correct evaluation and research of the grease under the actual working conditions of the bearing were carried out.Different components of grease were prepared according to the test requirements.Aiming at the most widely used lithium grease and polyurea grease,mineral oil-lithium grease and PAO oil-polyurea grease with paraffin mineral oil and PAO as base oil were prepared.Each grease is divided into four different cone penetration,namely four different cone penetration of mineral oil-lithium grease and four different cone penetration of PAO oil-polyurea grease.The results of metallographic microscope show that the fiber structure of grease with smaller cone penetration is denser,the winding degree is higher,and the network pore structure is more compact.Moreover,the micro fiber structure of PAO oil-polyurea grease is more winding than that of mineral oil-lithium grease.The influence of different grease cone penetration on Elastohydrodynamic friction characteristics of mineral oil-lithium grease was investigated.The results show that the mineral oil-lithium grease with different cone penetration is more sensitive to ambient temperature than rolling speed,and more sensitive to load than ambient temperature.The sensitivity of the mineral oil-lithium grease with different cone penetration to load and rolling speed is almost the same.The thermal stability of mineral oil-lithium grease with smaller cone penetration is better than that of mineral oil-lithium grease with higher cone penetration.The influence of different grease cone penetration on Elastohydrodynamic friction characteristics of PAO oil-polyurea grease was investigated.The results show that the PAO oil-polyurea grease with different cone penetration is more sensitive to ambient temperature than rolling speed,and more sensitive to load than ambient temperature.The sensitivity of the PAO oil-polyurea grease with different cone penetration to load and rolling speed is almost the same.The thermal stability of PAO oil-polyurea grease with smaller cone penetration is better than that of PAO oil-polyurea grease with higher cone penetration.The friction properties of PAO oil-polyurea grease with different cone penetration andmineral oil-lithium grease with different cone penetration were analyzed and compared.The experimental results show that the friction coefficient of mineral oil-lithium grease with different cone penetration is much larger than that of PAO oil-polyurea grease with different cone penetration under the same working conditions.Whether it is mineral oil-lithium grease with different cone penetration or PAO oil-polyurea grease with different cone penetration,when the ambient temperature is 130 ℃ and70 ℃,the friction coefficient of grease with higher cone penetration is relatively small.However,when the ambient temperature is 30 ℃,the friction coefficient of grease with larger cone penetration is relatively large.Under the same load and ambient temperature conditions,the PAO oil-polyurea grease with different cone penetration is more sensitive to the change of rolling speed than the mineral oil-lithium grease with different cone penetration.Under the same load and rolling speed conditions,PAO oil-polyurea grease with different cone penetration is more sensitive to temperature change than mineral oil-lithium grease with different cone penetration.At the same ambient temperature and rolling speed conditions,the sensitivity of PAO oil-polyurea grease with different cone penetration and mineral oil-lithium grease with different cone penetration are almost the same. |
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