Device and process for injection molding of hollow plastic parts

Process for injection molding of molded parts made from plastic material having at least one cavity, which includes:

• a) injection of plastic melt into the cavity of an injection-molding die from an injection unit along a melt flow path and through a first opening in the injection-molding die
• b) injection of a fluid into the still molten plastic material, so that the latter is pressed against the walls of the cavity, the fluid being injected into a second opening in the injection-molding die;
• c) allowing the plastic material to solidify until it forms the molded part in self-supporting manner;
• and
• d) releasing the molded part from the cavity of the injection-molding die;
• liquid being used as the fluid, which is injected at a preset pressure and a preset quantity, the liquid passing from a first part element of a means for injecting the liquid, which is arranged centrally, via a second part element of the means for injecting the liquid, which is arranged in the vicinity of the injection-molding die, to a third part element of a means for injecting the liquid, which is arranged locally on the injection-molding die, and is injected by the latter into the plastic melt.

Device for injection molding parts made from a plastic material, comprising:

• an injection unit for injecting plastic melt into a first opening in an injection-molding die;
• and
• a liquid injection unit for injecting a liquid into a second opening in the injection-molding die, including:
• a first part element disposed remotely from the injection-molding die;
• at least one second part element disposed in the immediate vicinity of the injection-molding die;
• and
• a third part element disposed locally on the injection-molding die at least during injection of the liquid.