Inventors:
Frederick G. Kudert - Niles IL
Maurice G. Latreille - Batavia IL
Robert J. McHenry - St. Charles IL
George F. Nahill - Crystal Lake IL
Henry Pfutzenreuter - Alta Loma CA
William A. Tennant - Schaumburg IL
Thomas T. Tung - Hoffman Estates IL
John Vella - Aurora IL
Assignee:
Pechiney Plastic Packaging, Inc. - Chicago IL
International Classification:
B29D 2300
B65D 140
Abstract:
Apparatus for unit cavity and multi-cavity, multi-layer injection molding and injection blow molding machines are provided, which in preferred embodiments, include: co-injection nozzle means including multi-polymer co-injection nozzles comprising an assembly of shells, and having fixed, tapered passageways communicating with annular orifices close to the nozzle gate and to each other, and polymer flow balancing and directing means in the passageways in the form of concentric and eccentric chokes; valve means for each co-injection nozzle, operative in the nozzle central channel to and adapted to be moved to different positions to block and unblock the nozzle orifices, and, in each nozzle to controls the initiation, flow and termination of flow of a plurality of polymer flow streams, comprised of an elongated sleeve having an axial central passageway and a port in its side wall and axially-reciprocable within the nozzle central channel, and, either a solid pin within and fixed relative to the sleeve, or, more preferably, an elongated pin axially-reciprocable within the sleeve central passageway, the sleeves and pins each mounted in close tolerance slip fits to prevent any significant accumulation of polymer melt material therebetween; valve means adapted to move through a nozzle central channel to assist in knitting the internal layer with itself in the central channel; valve means adapted to move through a nozzle central channel with an accumulation of polymer melt material at its forward end, and to assist in encapsulating the knit internal layer in what will be the sprue or bottom area of the container to be formed; valve means adapted to be moved through a nozzle central channel to substantially clear the central channel of polymer melt material; a feed block for each co-injection nozzle, for receiving a plurality of separate polymer melt material flow streams in an axially-aligned, spaced pattern in the periphery of the device, and for redirecting their travel paths to flow axially in a radially-spaced pattern out of the forward end of the device into the rear of a co-injection nozzle; polymer melt material flow stream splitter devices, including runner extensions, T-splitters and Y-splitters, for splitting an income flow stream channel for each melt material, into first and second branched flow channels of equal length which communicate with sets of first and second branched exit ports, each set in an axially-aligned, spaced pattern in different peripheral surface portions of the device; drive means in communication with separate valve means for each nozzle, for simultaneously and identically driving the valve means in each co-injection nozzle, to there simultaneously and identically initiate, regulate and terminate the flow of the respective polymer melt material streams, the drive means including a sleeve shuttle for each sleeve, a pin shuttle for each pin, each connected to common moving means including a sleeve cam bar and a pin cam bar; control means for moving the common moving means in a desired mode to provide the identical, simultaneous movements of the valve means and identical, simultaneous flow control of corresponding materials in each nozzle; a free floating runner system wherein runner means, including a runner block and its runner extension, are mounted on their axial center lines on support means, with a gap between the runner structures and surrounding structures to allow the runner structures to freely thermally expand radially and axially; a force compensation system comprised of means, preferably hydraulic, for providing a forward force to the runner structures to offset any rearward force from axial floatation of the runner means and to provide an on-line, effective pressure contact seal between the nozzle sprues and injection cavity sprues; a runner system providing a substantially equal flow path and experience to corresponding polymer melt material flow streams fed to corresponding passageways in each co-injection nozzle, for forming corresponding layers in each injected article; and apparatus for injection molding and blow molding multi-layer plastic articles, employing the valve means and a fewer number of means for displacing polymer melt materials than there are layers of such materials in the article formed; combinations of the aforementioned and other apparatus and devices, with and without the valve means, and with and without means for displacing and pressurizing each polymer melt material from its source to the co-injection nozzles. Methods for injection molding and injection blow molding articles by means of unit cavity and multi-cavity, multi-layer injection molding and injection blow molding machines are provided, which, in preferred embodiments, include: methods of initiating, regulating and terminating the respective flows of polymer melt material flow streams through the co-injection nozzle orifices, preferably with, but also without the use of valve means, to force thin articles, including parisons and containers comprised of at least three, preferably five layers; methods of doing the above with valve means, and with flow balancing and directing means, involving selectively moving the valve means to various positions which block and unblock the nozzle orifices to form the articles, to provide them with desired characteristics, and to control the relative thicknesses, uniformities and radial positions of the respective layers, especially the internal layer of the article; methods for doing the above with valve means, and with flow balancing and directing means, involving selectively moving the valve means to various positions which block and unblock the nozzle orifices to form the articles, to control the final lateral location of the internal layer within the wall of the injected article; methods of doing the above with and without valve means, and with flow balancing and directing means, in conjunction with pressurizing one or more polymer melt materials, to precisely control the relative flows of the respective polymer melt materials into and through the nozzle central channels and into the injection cavities; methods of initiating flow of a melt stream of polymeric material substantially simultaneously from all portions of an annular passageway orifice into the central channel of a co-injection nozzle of a multi-polymer injecting molding machine for forming multi-layer articles, by providing a melt material in the passageway while preventing the material from flowing through the orifice, subjecting the material to a pressure which at all points about the orifice is greater than the ambient pressure of a flowing melt stream of another polymeric material through the central channel, at all circumferential positions which correspond to said points, and allowing the pressurized material to flow through the orifice to obtain the simultaneous onset flow. The flowing pressurized material has a leading edge sufficiently thick about its annulus that the marginal end portion of the internal layer in the side wall of the injection molded article is at least 1% of the total thickness of the side wall.
