| 摘要 |
PURPOSE:To prevent the sliding surface of an impeller from rusting, by carrying out such a method that a molten material at a temperature in a range of 1380 deg.C+ or -10 deg.C is poured after a mouth ring formed in the peripheral suface thereof with a plurality of stepped projections and made of gun metals, is positioned in the suction stage of the impeller which is slidingly contacted with a pump casing section. CONSTITUTION:In the process of manufacturing an impeller 1, a molten material at a temperature in a range of 1380 deg.C+ or -10 deg.C, which is determined, as a suitable temperature range, by the result of numerous experiments, is poured after a mouth ring 3 formed in the peripheral surface thereof with a plurality of stepped projections 3a, 3b... and made of gun metals is disposed in the suction stage of the impeller 1 which serves as a sliding surface with respect to a pump casing section 2. In the drawing showing the process of the casing, reference numeral 4 denotes a drag mold, 5: an upper mold, 6: a core which is set after the mouth ring 3 is disposed in the drag mold 4. The thus formed impeller 1 never rusts on the sliding surface with respect to the pump casing 2, and therefore, smooth operation may be expected even after a rest for a long time. |
