Injection moulding hollow component and process equipment - involves injecting gas into melt in main cavity from where it flows to secondary cavity via restriction to force melt against walls

摘要

In mfg. a thermoplastic component with a hollow section, a two or more part tool (12) with a first cavity (3) and one or more secondary cavities (8) is used. The secondary cavity (8) is connected to the first cavity by a restricted zone (5). After injection of polymer into the first (3) and secondary (8) cavities and also the restriction (5), gas is forced into the melt in the first cavity (3) only. The gas bubble (15) formed flows through the restriction (5) into the secondary cavity (8) and forces melt against the walls of all areas of the cavities (3,8) and the restriction (5). Claimed equipment includes a two or more part tool (1,2) with a first cavity (31 linked to one or more secondary cavities (8) by restrictions (8) in the melt flow path to ensure at least part of the melt reaches the first cavity (3) from the secondary cavity (8). USE/ADVANTAGE - For injection of thermoplastic components with a hollow section e.g. carrying handles on bottle crates. Greater reproducibility of product quality. Prevents a build up of plastic in the corners of the hollow sections.