Causes and repair of shaft damage of water ring vacuum pump

At present, the shaft and impeller of water ring vacuum pump are all in one-stage dynamic fit, and there is no 0-type sealing ring at the keyway. The liquid in the pump (especially when the corrosive liquid is used as liquid ring in chemical industry) will enter the shaft hole through the fit clearance and keyway, which will corrode the shaft hole of the shaft and impeller, and greatly reduce the fatigue strength. The increase of fit clearance after corrosion and wear (some of which are ground into elliptical shaft holes) not only affect the performance, but also aggravate the vibration and promote fatigue fracture.

The general water ring vacuum pump shaft has not been heat treated, so the fatigue strength is low. In order to prevent fracture, the pump shaft should at least be quenched and tempered, and nitriding treatment should be carried out where conditions permit.

In the design, it is necessary to avoid large section mutation. Fillet connections are applied instead of sharp corners at the transition. The surface finish should not be low, especially in the place where the shaft is easy to break. During the processing, the circumferential machining of the transition parts of different shaft diameters should ensure the quality, and the size and smoothness required by the drawings should be strictly followed. There should be no knife marks, scratches, bumps and other defects on the surface and transition of the pump shaft.

The fatigue damage of pump shaft is very harmful to production, which is a problem of great concern to users. The solution is: according to the size of radial force to check the fatigue strength of the pump shaft, when using corrosive gas and liquid ring, the corresponding corrosion-resistant materials should be used, the pump shaft must be quenched and tempered, and the quality must be guaranteed during processing.

Water Ring Vacuum Pump

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