Individual cavity flow control methods and systems for co-injection molding
AssigneeMilacron LLC
InventorsJohn Duffy, Scott Hickey
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Abstract
Methods and systems for co-extruding multiple polymeric material flow streams into a mold having a plurality of cavities to produce a plurality of multi-layer polymeric articles each having a consistent coverage of an interior core layer are disclosed herein. In an example method, a flow rate of a first skin material into a cavity is individually controlled for each cavity before initiation of co-injection of a second core material into the cavity, which may address inconsistent interior core layer coverage for articles from different cavities.
Claims14
A method of individually controlling a position of a leading edge of an interior layer during co-injection molding of a plurality of multi-layer articles using a corresponding plurality of cavities of a mold, the method comprising:
- for each cavity in the plurality of cavities, individually controlling a flow rate of a first material into each cavity using a position of a valve pin in a corresponding nozzle of a plurality of nozzles, each nozzle of the plurality of nozzles configured to form a three-layer combined polymeric plastic flow stream therein, the three-layer combined polymeric plastic flow stream comprising an interior stream of a second material encased by an inner stream of the first material and an outer stream of the first material;
- for each cavity in the plurality of cavities, co-injecting from the corresponding nozzle of the plurality of nozzles the second material into the respective cavity with the first material using the corresponding nozzle thereby forming the interior layer of the second material between the inner layer of the first material and the outer layer of the first material in the respective cavity;
- and
- for each cavity in the plurality of cavities, blocking flow of the inner stream of the first material within the corresponding nozzle with the valve pin to cease flow of the inner stream while continuing flow of the outer stream of the first material and flow of the interior stream of the second material into the cavity to form a two-layer combined polymeric plastic flow stream.
A method of individually controlling a position of a leading edge of an interior layer during forming of a plurality of multilayer injection-molded articles using a corresponding plurality of cavities of a mold, the method comprising:
- initiating injection of a first material at a first time into a first cavity of the plurality of cavities using a first nozzle with a valve pin of the first nozzle in a first position before co-injection of a second material into the first cavity, the first nozzle configured to form a three-layer combined polymeric plastic flow stream therein, the three-layer combined polymeric plastic flow stream comprising an interior stream of a second material encased by an inner stream of the first material and an outer stream of the first material;
- initiating injection of the first material at a second time different than the first time into a second cavity of the plurality of cavities using a second nozzle with a valve pin of the second nozzle in a second position different than the first position, thereby restricting flow of the first material into the second cavity before co-injection of the second material into the second cavity, the second nozzle configured to form a three-layer combined polymeric plastic flow stream therein, the three-layer combined polymeric plastic flow stream comprising an interior stream of the second polymeric material encased by an inner stream of the first polymeric material and an outer stream of the first polymeric material;
- co-injecting the second material after a first time delay relative to the first time into the first cavity with the first material using the first nozzle thereby forming an interior layer of the second material between an inner layer of the first material and an outer layer of the first material in the first cavity;
- and
- co-injecting the second material after a second time delay relative to the second time into the second cavity with the first material using the second nozzle thereby forming an interior layer of the second material between an inner layer of the first material and an outer layer of the first material in the second cavity, and
- using the valve pin of the first nozzle to individually control the position of a leading edge of the interior layer in a first resulting multilayer injection-molded article formed in the first cavity and using the valve pin of the second nozzle to individually control the position of a leading edge of the interior layer in a second resulting multilayer injection-molded article formed in the second cavity.
Dependencies are inferred from the claim text.