| 摘要 |
PURPOSE:To facilitate an operation for removing core sand after molding and to prevent penetration of a molten metal in a collapsible insert core by enclosing the outside peripheral face of the core in the cavity of metallic molds, then controlling the speed of an injection plunger. CONSTITUTION:The molten metal is injected through both sleeves 38, 58 and a runner gate 36 into the cavity 35 when oil is fed into an injection cylinder 55 after completion of closing of the two metallic molds 30, 32. The top surface of the molten metal arrives at about a constricted part 36 at this time and increases the speed of the plunger 59 so that the molten metal is carried fast. The top surface of the molten metal arrives next at the collapsible insert core 1 set in the mold 32 and completely encloses the surface of the core 1 to drop the speed of the plunger 59 so that the molten metal is prevented from splashing in the cavity 35 until a switch 102 is actuated. Packing is not completed yet in this state. The plunger speed is then dropped by the switch 102 to the speed at which the time for the solidified layer formed on the surface of the core 11 to grow to about the extent to withstand the casting pressure takes. The packing is thus sufficiently completed.
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