| 摘要 |
PURPOSE:To eliminate the generation of a blowhole and the formation of a residual solidified section, by lowering a piston set on the hollow section of a cope, gradually from a specified level, on the solidification of molten metal. CONSTITUTION:Firstly, a mandrel 35 and a laminated core 11 are placed between a cope 19 and a drag 28 through the upper and lower sections in the axial direction, and molten metal is injected through the pouring gate 33 of the drag 28. When a molten metal contained in the respective sections of the drag 28 and the cope 19 starts to be solidified, then a piston 26 is gradually lowered through a specified level to press the molten metal. With the start of the solidification, the volume of the molten metal is shrunk, but the shrunk content is supplemented with molten metal extruded by the piston 26, and so a blowhole is not generated. If the piston 26 is lowered through a specified level, the lower surface of the piston 25 is positioned on the upper surface 22a of a salient section molding cavity section 22 for fitting a balancer, on the completion of the solidification, and a residual solidified section is not formed on the salient section for fitting the balancer.
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