A Multi-phase Micro-abrasive Jet Machining Technique For The Surface Texturing Of Mechanical Seals

The mechanical seals are widely used in petroleum, chemical, metallurgy, nuclear and aerospace industries to avoid the leakage of fluids by mutual mating the faces of rotating and stationary rings for its good sealing, long life, low power consumption. However, mechanical seal existing increasingly difficult to meet the requirements of high-pressure, high-speed, complex media in modern machines. Surface texture has been proven as an effective means to improve the tribological and sealing properties of mechanical seals. By fabricating various patterns of grooves or dimples in macro- or micro- scale on the mating surfaces, additional hydrodynamic pressure could be generated to increase the load carrying capacity and the fluid film stiffness between the rotating and stationary rings. Many machining techniques have been developed for the fabrication of surface texture such as micro-cutting, electrochemical machining and laser machining, but all of them have some limitations and shortcomings, limiting research and engineering applications of surface texturing of mechanical seals. Therefore, a technique of multi-phase micro-abrasive jet machining is proposed to fabricate surface texture on the surface of mechanical seals in this paper, and the following works have been done:(1) Proposed a technique of multi-phase micro-abrasive jet machining to fabricate surface texture on the surface of mechanical seals. This technique takes the advantages of the current micro-abrasive jet machining, and can recycle the abrasive particles easily to avoid the pollution on the environments by accelerating the mixture of abrasives and water with a relative low pressure of air.(2) Determined the design idea and design goals of multi-phase micro-abrasive jet machining system, and finished the design of overall project, nozzle, air circuit and mobile platform. Designed machining system in this paper could transform the abrasive solution into multi-phase micro-abrasive jetting under conditions of low air pressure, and has simple overall structure, high gas path reliability, convenient operation and maintenance and other advantages.(3) Explored the masking process based on copper foil tape and through mask electrochemical micromachining, stainless steel sheet and laser machining. The results showed that the mask made of copper foil tape has relatively high accuracy and is suitable for machining of micro-structure. The mask made of stainless steel sheet has simple process and could be used repeatedly. Then the abrasives, jet distance and feed mode were determined and detailed processing process and some cautions were listed.(4) The multi-phase micro-abrasive jet machining was used for the micro-grooves machining for the typical materials such as RBSC, SUS304, and carbon graphite for mechanical seals. The machining effects on three typical materials for mechanical seals are investigated and compared and the influences of machining times, abrasive flow rate, jet pressure, and jet distance on machining quality are studied and optimized through experiments.