Molding method and molding apparatus

A molding method that uses a molding apparatus that is provided with a mold having a cavity, an injection sleeve that has a molten metal supply port and is communicated with the cavity, a molten metal furnace within which molten metal is stored, a connecting portion that connects the molten metal furnace to the injection sleeve by one end of the connecting portion being connected to the molten metal furnace and the other end of the connecting portion being connected to a location opposite the molten metal supply port, a pump that is arranged in the connecting portion and pumps up molten metal from the molten metal furnace, a valve that is arranged in the connecting portion, and that forms a molten metal holding space that holds the molten metal pumped up by the pump, in the connecting portion, and a pressure-reducing portion that is arranged in a portion of the connecting portion where the molten metal holding space is located, and that reduces pressure in the molten metal holding space, the molding method comprising:

• forming the molten metal holding space inside the connecting portion by closing the valve;
• pumping up the molten metal from the molten metal furnace into the molten metal holding space of the connecting portion with the pump;
• reducing a pressure of the molten metal pumped up into the molten metal holding space with the pressure-reducing portion;
• communicating the molten metal holding space of the connecting portion with the molten metal supply port of the injection sleeve by opening the valve;
• and
• supplying the molten metal, the pressure of which has been reduced inside the molten metal holding space, into the injection sleeve.

A molding apparatus comprising:

• a mold having a cavity;
• an injection sleeve that has a molten metal supply port and is communicated with the cavity;
• a molten metal furnace within which molten metal is stored;
• a connecting portion that connects the molten metal furnace to the injection sleeve by one end of the connecting portion being connected to the molten metal furnace and the other end of the connecting portion being connected to a location opposite the molten metal supply port;
• a pump that is arranged in the connecting portion and pumps up molten metal from the molten metal furnace into the connecting portion,, and supplies the molten metal into the injection sleeve via the connecting portion;
• a valve that is arranged in the connecting portion, and that forms a molten metal holding space that holds the molten metal pumped up by the pump, in the connecting portion;
• and
• a pressure-reducing portion that is arranged in a portion of the connecting portion where the molten metal holding space is located, and that reduces pressure in the molten metal holding space,
• wherein the injection sleeve performs an operation of injecting the molten metal into the cavity;
• the molten metal holding space is formed by closing the valve;
• the pump pumps up the molten metal into the molten metal holding space of the connecting portion;
• the valve communicates the molten metal holding space of the connecting portion with the molten metal supply port of the injection sleeve by opening, and supplies the molten metal, the pressure of which has been reduced inside the molten metal holding space, into the injection sleeve.