Methods and apparatus for maintaining a pressure contact seal between nozzles and cavities of an on-line injection molding machine

A multi-coinjection nozzle injection molding apparatus for an injection molding machine, which comprises,

• runner means having channels for a plurality of polymeric material streams, and having a forward end with a plurality of co-injection nozzles mounted therein each having means for receiving the plurality of streams and for substantially simultaneously co-injecting a plurality of polymeric materials therefrom, each having an exposed sprue face mounted adjacent the runner means forward end,
• a member mounted to the machine and having a plurality of injection cavities mounted therein each having a sprue face for in communication with a juxtaposed nozzle sprue face,
• support means for supporting the runner means,
• mounting means for mounting the runner means on the support means, said runner means and support means being adapted to allow the runner means to float axially on the support means on the center line of the apparatus while the machine is in operation, and
• means for providing to the runner means a forward force sufficient to compensate for the rearward force from axial floatation of the runner means due to injection back pressure translated through the runner means, and sufficient to provide and maintain an effective pressure contact seal between the nozzle sprue faces and the cavity sprue faces during operation of the machine.

A multi-coinjection nozzle injection molding apparatus for an injection molding machine, which comprises,

• runner means having channels for a plurality of polymeric material streams, and having a forward end with a plurality of co-injection nozzles mounted therein each having means for receiving the plurality of streams and for substantially simultaneously co-injecting a plurality of polymeric materials therefrom, each having an exposed sprue face mounted adjacent the runner means forward end,
• a member mounted to the machine and having a plurality of injection cavities mounted therein each having a sprue face for communication with a juxtaposed nozzle sprue face,
• support means for supporting the runner means,
• mounting means for mounting the runner means on the support means, said runner means and support means being adapted to allow the runner means to float axially on and radially from the center line of the apparatus while the machine is in operation, and
• means for providing to the runner means a forward force sufficient to compensate for the rearward force from axial floatation of the runner means due to injection back pressure translated through the runner means, and sufficient to provide and maintain an effective pressure contact seal between the nozzle sprue faces and the cavity sprue faces during operation of the machine.

Multi-coinjection nozzle injection molding apparatus for an injection molding machine, which comprises,

• a moveable platen,
• support means including first fixed support means spaced from the moveable platen, and second support means
• runner means having channels for a plurality of polymeric material streams, and having a forward face with a plurality of co-injection nozzles mounted therein each having means for receiving the plurality of streams and for substantially simultaneously co-injecting a plurality of polymeric materials therefrom, positioned between the moveable platen and fixed support means for providing a plurality of separate polymer streams to each co-injection nozzle, said second support means including a member mounted to the machine and adapted to be positioned adjacent the forward face of the runner means, having a plurality of injection cavities mounted therein each one juxtaposed to and having its prue in communication with the fixed support means and positioned between it and the moveable platen, for maintaining the injection cavities substantially in a common plane and the co-injection nozzle faces substantially in a common plane, and for protecting and preventing damage to the runner means due to the clamping force exerted by the moveable platen relative to the fixed support means, the runner means, fixed support means and support means each being adapted to allow the runner means to float axially on the center line of the apparatus to accommodate injection back pressure exerted axially through and thermal expansion of the runner means, and
• means for providing to the runner means a forward force sufficient to compensate for the rearward force from axial floatation of the runner means, and sufficient to provide and maintain an on-line effective pressure contact seal between the nozzle sprue faces and cavity sprue faces.

A method of providing and maintaining an effective pressure contact seal between a plurality of co-injection nozzle faces with a plurality of respectively juxtaposed injection cavity sprue faces during the operation of a multi-coinjection nozzle injection molding machine having runner means for distributing a plurality of polymeric material streams to each of the co-injection nozzles mounted in the forward end of the runner means for substantially simultaneously co-injecting a plurality of polymeric material streams therefrom, which comprises,

• mounting the runner means or its axial center line on suitable support means,
• moving the plurality of polymeric material streams from the runner means to each of the coinjection nozzles for substantially simultaneously coinjecting said plurality of polymeric material streams therefrom,
• allowing the runner means to float axially on its axial center line to accommodate any axial thermal expansion thereof and to accommodate injection back pressure exerted through the runner means during the operation of the machine, and
• compensating for the rearward force exerted through the runner means during said axial floatation, by exerting on the runner means through and along its axial center line a forward force sufficient to compensate for the rearward force and sufficient to provide and maintain an effective pressure contact seal between the nozzle sprue faces and the cavity sprue faces during operation of the machine.

A method of providing and maintaining an effective pressure contact seal between a plurality of co-injection nozzle faces with a plurality of respectively juxtaposed injection cavity sprue faces during the operation of a multi-co-injection nozzle injection molding machine having runner means for splitting and distributing a plurality of polymeric materials to each of the co-injection nozzles mounted in the forward end of the runner means for substantially simultaneously co-injecting a plurality of polymeric material streams therefrom, which comprises,

• mounting the runner means or its axial center line on suitable support means,
• moving the plurality of polymeric material streams from the runner means to each of the co-injection nozzles for substantially simultaneously co-injecting said plurality of polymeric material streams therefrom,
• allowing the runner means to float axially on its axial center line to accommodate any radial and axial thermal expansion thereof and to accommodate injection back pressure exerted through the runner means during the operation of the machine, and
• compensating for the rearward force exerted through the runner means during said axial floatation, by exerting on the runner means through and along its axial center line a forward force sufficient to compensate for the rearward force and sufficient to provide and maintain an effective pressure contact seal between the nozzle faces and the cavity sprue faces during operation of the machine.