| 摘要 |
PURPOSE:To manufacture a casting without cavity even on the side opposite to the gate side by dividing a cope in the vicinity of the axially central part of an end ring, causing an L-type first pipe and further second pipe to communicate with each other for ventilation and fitting a valve freely opening and closing a duct downstream from said first pipe. CONSTITUTION:If a second pipe 13 is ventilated as shown by the arrow from just before starting of casting, a pressure lowers in adjacent parts communicating with the valve 14 in the second pipe 13. Therefore, air in adjacent parts such as cooling fin forming grooves 4a, 4b flows into a first pipe 12 as shown by the arrow (a), passes through the second pipe 13 and is discharged outward. Further, by a push-out effect of cast conductor 15 and a suction effect in the second pipe 13, air is surely discharged outward and generation of cavity by involvement of gas is prevented. On the other hand, a molten metal conductor having entered the first pipe 12 is biased by closing of a duct in the second pipe 13 with the valve 14 after completion of casting. Therefore, a shrinkage at the time of solidification of an end ring 5 can be completely supplied by a molten metal conductor in the first duct 12. As a result, it is possible to prevent generation of cavity and shrinkage cavity in the end ring 5 on the side opposite to the gate side.
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