Injection molding machine and injection molding method

摘要

An injection molding machine having a simple structure and adapted to quickly operate for injection molding without taking in air bubbles is provided. The injection molding machine comprises a plunger and a nozzle for injecting the molten metal fed from the plunger into a metal mold. The plunger has a cylinder section with a through hole bored through an upper portion of its lateral wall for introducing the molten metal, and a piston for slidingly reciprocating within the cylinder section. A communication hole is bored through the piston and communicates with the through hole at a predetermined position. The communication hole runs from the lateral wall of the piston through the inside thereof and has a non-return valve arranged therein to allow only a flow from the lateral wall of the piston.