Analysis Of Reciprocating Seal

Four problems have been investigated in this thesis, i.e., finite element analysis of the structural mechanics of seal, fluid lubrication of rod seal, reciprocating sealing mechanism, and frictional experiment on polyurethane sealants.Firstly, Software ANSYS 12.0 was used to establish the three-dimensional model for representative lip-seal. The stress distribution on seal and on interface was simulated during the seal assembling, fluid pressure loading, instroke and outstroke of hydraulic cylinder. Distribution regularities of stress on seal and on interface were concluded according to the calculation result.Secondly, a lubrication model for rod seal was established based on parallel gap , mechanism of fluid lubrication for seal was studied assumed that the temperature of the moving surface is constant and the static surface is adiabatic. The thermal effect and the geometrical wedge effect of microstructure.were given. Results show that the dynamic oil film pressure was determined by the geometrical wedge under isothermal conditions, so dynamic oil film pressure couldn't be created between two smooth parallel surfaces. However, dynamic oil film can be formed when the relative sliding speed is high enough and the thermal effect is included. For the rough seal surface under thermal condition, the formulation of oil film pressure distribution was attributed to the comprehensive action of the geometrical wedge by asperity and the thermal effect.Thirdly, refering to frictional test on reciprocating flexible seal conducted by Kaneta, et al. and others, cross sectional model of seal was established to analyze the lubricant film formation mechanism during instroke and outstroke of hydraulic cylinder, a method for calculating the distribution of pressure and temperature in various cross sectional wedgelike gap was presented, and the influence of different cross sectional shape on sealing effect was discussed for both instroke and outsroke per cycle.Lastly, influence of contact pressure, relative sliding speed, and lubrication state on friction and wear properties of new-type polyurethane was studied by experiment. Discontinious sliding occurred during the dry friction motion between the block and the ring. The lubricant film was easily formed on the interface as long as the lubricant oil exists, and the friction force was influenced significantly by interface temperature in the process of the experiment.