| 摘要 |
PROBLEM TO BE SOLVED: To provide a gravity casting machine which can freely set a dropping speed without relying upon the gravity, the dropping speed having a most remarkable effect on the relationship between the filling rate and the speed of molten metal. SOLUTION: A hydraulic servo mechanism 16 is arranged between a speed control valve 14 and a hydraulic cylinder 17. The hydraulic servo mechanism 16 is used for damping and controlling a vibration, and is added at the back of the speed control valve 14. When the gravity casting is carried out, the casting machine is tilted from 0°to 90°by the extending motion of the hydraulic cylinder 17 while extending and contracting it within the range of a response frequency. In this case, the frictional resistance greatly decreases by the minute vibration due to the extension and contraction of the hydraulic cylinder 17, and the molten metal drops while being accelerated by the effect of inertia. When the molten metal flows into the cavity of a metallic die 1, gas is necessarily generated. However, the air and gas existing in the cavity of the metallic die 1 are forcedly discharged by incorporating the hydraulic servo mechanism 16 as an exciting means of the hydraulic cylinder 17. COPYRIGHT: (C)2007,JPO&INPIT
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