Injection molding machine

摘要

An injection molding machine comprises an injection piston-cylinder mechanism including therein an injection piston and a booster piston. The booster piston is provided with a longitudinal through hole through which a pressurized fluid is supplied from an external source into the piston-cylinder mechansim so as to act on the injection piston to fill the mold cavity with molten bath. When the inner pressure of the cylinder chamber between both pistons reaches a predetermined value or the injection piston reaches a predetermined position, a valve assembly which is connected to the cylinder chamber through a conduit is operated so as to drain the pressurized fluid in the cylinder chamber in a controlled manner thereby to advance the booster piston.