| 摘要 |
PURPOSE:To simplify the manufacture of a Roots type pump rotor by forming plural number of resin passages over the whole molding cavity, in the peripheral direction, pouring resin in every other passage, and allowing said resin to be discharged through the remaining passages. CONSTITUTION:On the outer periphery of a rotor body 10, is formed a molding cavity 24, in which resin passages 26, 27 are provided. With the rotor body 10 kept inserted, resin is poured in every other resin passage out of plural resin passages, and discharged through the remaining resin passages. Accordingly, resin poured in a metal mold flows only between the adjacent resin passages in the molding cavity, thereby, sharply reducing the distance of flow, reducing flow resistance, and saving labor for the following machining.
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