Process for controlling gas blanket extent in plastics injection molding

Abstract

A process and a device for the injection molding of plastic objects of thermoplastic, duraplastic, or elastomeric material implements the steps of: a) injecting a sufficient quantity of molten plastic into cavity (,) of a mold (,) along a melt flow path, which extends from a unit (,) for plasticizing and injecting the plastic through a plastic injection nozzle (,) into mold (,); b) introducing a pressurized fluid, particularly a pressurized gas, from a wall (,) of cavity (,) through at least one fluid injection element (,), so that a fluid blanket (,) forms between wall (,) of cavity (,) and the plastic introduced into the mold; c) allowing the molded part thus produced to harden; d) relieving the cavity (,) of the pressure of the pressurized fluid; and e) demolding the molded part. It is provided according to the invention that at least one surface projection (,) is provided in the mold (,), on the cavity wall (,), such that its upper plateau (,) runs extensively parallel to the cavity wall (,). The pressurized fluid is injected by means of at least one fluid injection element (,) in the region of upper plateau (,) of the surface projection (,), such that fluid blanket (,) forms between the plastic and upper plateau (,) of surface projection (,). Thus, the fluid blanket is controlled to be limited in its extent.