Nozzle for injecting gas into injection mouldings without clogging - consists of porous tube made of sintered metal but whose cavity end is only open at specific points for maximum effectiveness

摘要

A gas nozzle for injection moulding machines introduces gas or gases (e.g. an inert gas) into the mould cavity which is already partly or completely filled with the shot; it injects through the cavity wall at at least one point which does not coincide with that of the injection nozzle for the melt (with or without its gate). At least one end of the gas injecting nozzle into the cavity is made of a porous sintered metal; this forms at least part of the inside wall of the nozzle concerned; it is closed at the cavity end but for specific points where alone it allows the gas(es) to enter the cavity. Pref., the layout shown has the mould clamping plates (2,3) and mould tools (5,6), with the cavity (7) fed through the bore (9) with the melt (10). The gas injector nozzle (11) projects into the cavity (7) and is attached to the one plate (6). It contains the closed gas bore (12) connected to the main gas supply (13). At least the cavity end (15) of the gas injector (11) is a porous sintered metal e.g. produced by powder technique. It is e.g. roughened only at certain points (16) to allow gas to emerge into the cavity (7), using e.g. nitrogen. In service at least the end (15) of the cavity is filled with melt (10) before the gas is injected at those points (16). ADVANTAGE - The nozzle has a simple design. It does not allow melt to penetrate into its gas outlets and hence it eliminates clogging when the melt solidifies.