| Rotary lip oil seal is one kind of important seals,which is widely applied in all kinds of mechanical equipment.The sealing failure of oil seals has a serious effect on equipment and environment,so it is important to pay enough attention on the design of rotary lip oil seals.Currently,the design of rotary lip oil seals in China mainly depends on the experience designing and rough macro analysis,and the performance of oil seal can only be known by experiment on products,which is both time-consuming and laborious..Many people have studied the oil seal,but most of the studies only include theory analysis.In this article,experiment and numerical simulation are combined to analyse the pumping friction and heating effect of oil seal to verify the effectiveness of the numerical method and numerical model.The experiment is made up of two parts.Part one is the pumping experiment of oil seal-measuring pumping rate of oil seal in different shaft speeds,interference and stiffness coefficient of spring.Part two is the experiment of temperature measurement-using an thermal imager to measure the temperature of shaft surface in different oil temperature and stiffness coefficient of spring.Then element model of the seal used in experiment is built to simulate Cauchy contact stress and contact width.A CFD model of seal used in experiment is built to simulate the temperature field to compare with experiment results.In addition,the model of themogenesis is built to study temperature field and heat-transfer of seal lip in different shaft speeds,oil temperature and interference.The results of CFD simulation and infrared temperature measuring experiment are accordant by comparison.The deviation between them is within 3K and variation tendency is similar.On account of the influence of micro roughness on seal lip and shaft surface to fluid flows in the process of numerical simulation,the pumping rate calculated with formula differs from experiment results.However,both of them have the same tendency along with the change of shaft speed and interference.This proves that the pumping rate calculating formula is practicable.Within the design of oil seal,designers could use the formula concerned to calculate the pumping rate and build related models to predict temperature field,and this can cut down unnecessary wasting of resources.The simulation results of themogenesis model shows that when an oil seal is working,the high temperature area is the seal lip.And the maximum temperature is concentrated increases obviously with the increase of shaft speed.Most of friction heat is transmitted into shaft,and then transferred into oil and air.The friction heat production rate increases with shaft speed as long as magnitude of interference,and it decreases with the increase of oil temperature.When magnitude of interference is too large,the shear stress of oil between sealing clearance exceeds limit,and lubrication film is unable to form completely,so the sealing fails. |
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