Sequential Injection Molding
Injection molding processes for performing sequential shots of different polymer materials are well known. To accomplish such processes, injection molding apparati have been developed using hotrunner systems that are designed to deliver sequential shots of polymer material both to a single cavity and to a plurality of cavities. In multi-cavity applications, shots are intended to be delivered at the same time in the same amounts and at the same rates of flow by controlling the length and configuration of the hotrunner flow channels and the temperature of various portions of the hotrunner and the injection nozzles and the mold cavity itself. However, in practice, it is very difficult to achieve such uniform delivery to multiple cavities. [Nahill et al, US Patent 7,892,462 (2/22/2011)]
Recent US Patents
9/20/2011
8,021,587
Method and apparatus for delivering sequential shots to multiple cavities to form multilayer articles
Armstrong and Nahill of Graham Packaging Company, Pennsylvania, developed a method for sequentially delivering multiple shots of polymer material to several mold cavities to form multilayer articles. (RDC 9/20/2011)
2/22/2011
7,892,462
Controlling delivery of polymer material in a sequential injection molding process
Nahill et al of Graham Packaging, Pennsylvania, developed a method for sequential shots during injection molding controlled by sensors in each cavity of the mold. (RDC 9/3/2011)