The Study Of Design And Manufacture Mechanism Of The Mechanical Seal Ring Face Structure

The sliding faces of sealing rings are the dominant sealing faces in the mechanical seals which play an important role in determing performance of the friction, wear and the sealing mechanical face seals. In order to improve the sealing performance and the lubrication between the clearance of sealing faces of mechanical seals, surface texturing technology has been used in the mechanical seal and various geometry forms in the seal faces has been processed, which is an effective method, to work without contacting and leaking.A new type of mechanical seal with micro lubricative pores and macro pumping grooves on the seal ring face is introduced, and a preliminary design on the micro and macro geometrical shape of its surface is carried out based on hydrodynamic pressure lubrication theory. Adopting advanced laser surface texturing and using the laser processing technology called "single pulse at a time, repeat at intervals", an experiment of laser modeling technology on Sic sample has been made and the influence of laser parameters, namely, the deferent wavelength, the deferent power, pulse width, repetition frequency, overlap coefficient, number of replication and auxiliary air, on the quality of geometrical shape by modeling on Sic materials is analyzed. High quality of micro lubricative pores and macro pumping grooves on the mechanical seal ring face has been successfully processed, which solves the difficulties of crossing dimension processing on the mechanical seal ring face. Based on the theory of fluid liquid hydrodynamic lubrication film form, a mathematics model is developed to allow performance prediction of fluid liquid hydrodynamic lubrication for mechanical seals with regular micro-surface geometrical structure. And then, use multi-grid method to solve the mathematics model with Reynolds cavitation boundary condition. Dimensionless average pressure of the film between the two sliding faces is used to estimate the performance of the lubrication, analyzing the connections between mechanical seal operation parameters, such as the rotation speed, the viscosity and seal clearance, and micro-pores geometry parameters, such as the area density of the pores and the pore depth over pore diameter ratio, and the Dimensionless average pressure. Increasing the seal parameter (corresponding to an increase of the rotation speed N or the viscosityμ, or decrease of seal clearance c) leads to more efficient hydrodynamic effect of the micro-pores. There is the existence of optimal area density of pores and pore depth, at any given pore diameter, to maximize the dimensionless average pressure. The area density of pores, S_p, has little effect on the dimensionless average pressure. However,the pore depth over pore diameter ratio has great effect on the dimensionless average pressure and the optimal ratios vary from the seal clearances. Besides, although increasing in the hydrostatic pressure can improve the dimensionless average pressure, the regions of cavitation over pores are eliminated by increasing hydrostatic pressure, hence, reducing the efficiency of the hydrodynamic effect of the pores. When the hydrostatic pressure is too great, the pressure increase in the converging film regions is counteracted by the pressure drop in diverging film regions so that fluid film will lose the capacity of sealing and protection. Thus, local cavitation is the key for obtaining hydrodynamic pressure or load-carrying capacity between parallel sliding faces.