Multi-cavity, co-injection molding apparatus

A multi-cavity, co-injection molding apparatus comprising:

• (1) a plurality of similar modules, each of which comprises:
• (a) a polymer injection mold defining an injection molding cavity;
• (b) a co-injection nozzle incorporating a gate opening in communicating with said molding cavity, and a polymer flow chamber extending from said gate opening and defined by an annular chamber wall;
• (c) an elongate gate member slidably supported for longitudinal movement in said nozzle and extending through said polymer flow chamber with uniform circumferential clearance from said chamber wall, said gate member defining at one end thereof a gate valve adapted for entering said gate opening thereby to close said gate opening, and said clearance providing a path for polymer flowing through said flow chamber to said gate opening;
• (d) a gate actuator connected to said gate member and adapted for alternative actuation thereby to move said gate member axially alternatively in a direction to cause said gate valve to enter and thereby close said gate opening, or in an opposite direction to withdraw said gate valve and thereby open said gate opening;
• (e) three polymer flow ducts formed in said nozzle, each said duct having an inlet end and an outlet end, said outlet end defines an annular port opening into said polymer flow chamber at said chamber wall, said ports encircling said gate member, beign spaced axially apart, and constituting a central port and respective outer ports spaced on either side of said central port;
• (f) three polymer injectors, each having respective injector polymer outlet and inlet ducts and a movable injector ram;
• (g) respective connecting means connecting the respective injector polymer outlet ducts with the respective inlet ends of said polymer flow ducts of said nozzle;
• (h) respective non-return valves connected respectively to the respective injector polymer inlet ducts, thereby to prevent the back-flow of polymer from the injectors;
• (i) first, second and third polymer inlet pipes connected to the respective non-return valves;
• (j) respective injector actuators drivingly connected to the respective injector rams;
• and
• (k) respective injector control means connected to the respective injector actuators and adapted to control the positions of the respective injector rams according to respective predetermined ram position-time cycles;
• (2) two polymer supply manifolds, each having a plurality of outputs and a single input;
• (3) a first set of polymer distribution pipes connecting the respective outputs of a first one of said polymer supply manifolds with the respective first and third polymer inlet pipes of the respective modules;
• (4) a second set of polymer distribution pipes connecting the respective outputs of a second one of said polymer supply manifolds with the respective second polymer inlet pipes of the respective modules;
• (5) a first polymer plasticizer connected to the input of said first polymer supply manifold and adapted to supply a first hot polymer to said first polymer supply manifold continuously;
• (6) a second polymer plasticizer connected to the input of said second polymer supply manifold and adapted to supply a second hot polymer to said second polymer supply manifold continuously;
• and
• (7) respective heating means for maintaining the respective polymers at their respective working temperatures during their passage from the respective plasticizers to the respective injection molding cavities;
• whereby in each said module, said first hot polymer is supplied by respective injectors to said outer ports in said co-injection nozzle, and said second hot polymer is supplied by one said injector to said central port in said co-injection nozzle.

A multi-cavity, co-injection molding apparatus comprising:

• (1) a plurality of similar modules, each of which comprises:
• (a) a polymer injection mold defining an injection molding cavity;
• (b) a co-injection nozzle incorporating a gate opening in communication with said molding cavity, and a polymer flow chamber extending from said gate opening and defined by an annular chamber wall;
• (c) an elongate gate member slidably supported for longitudinal movement in said nozzle and extending through said polymer flow chamber with uniform circumferential clearance from said chamber wall, said gate member defining at one end thereof a gate valve adapted for entering said gate opening thereby to close said gate opening, and said clearance providing a path for polymer flowing through said flow chamber to said gate opening;
• (d) a gate actuator connected to said gate member and adapted for alternative actuation thereby to move said gate member axially alternatively in a direction to cause said gate valve to enter and thereby close said gate opening, or in an opposite direction to withdraw said gate valve and thereby open said gate opening;
• (e) five polymer flow ducts formed in said nozzle, each said duct having an inlet end and an outlet end, said outlet end defines an annular port opening into said polymer flow chamber at said chamber wall, said ports encircling said gate member, being spaced axially apart, and constituting a central port, two intermediate ports spaced on either side of said central port, and two outer ports spaced respectively outward of said intermediate ports;
• (f) five polymer injectors, each having respective injector polymer outlet and inlet ducts and a movable injector ram;
• (g) respective connecting means connecting the respective injector polymer outlet ducts with the respective inlet ends of said polymer flow ducts of said nozzle;
• (h) respective non-return valve connected respectively to the respective injector polymer inlet ducts, thereby to prevent the back-flow of polymer from the injectors;
• (i) first, second, third, fourth and fifth polymer inlet pipes connected to the respective non-return valves;
• (j) respective injector actuators drivingly connected to the respective injector rams;
• and
• (k) respective injector control means connected to the respective injector actuators and adapted to control the positions of the respective injector rams according to respective predetermined ram position-time cycles;
• (2) three polymer supply manifolds, each having a plurality of outputs and a single input;
• (3) a first set of polymer distribution pipes connecting the respective outputs of a first one of said polymer supply manifolds with the respective first and fifth polymer inlet pipes of the respective modules;
• (4) a second set of polymer distribution pipes connecting the respective outputs of a second one of said polymer supply manifolds with the respective second and fourth polymer inlet pipes of the respective modules;
• (5) a third set of polymer distribution pipes connected the respective outputs of a third one of said polymer manifolds with the respective third polymer inlet pipes of the respective modules;
• (6) a first polymer plasticizer connected to the input of said first polymer supply manifold and adapted to supply a first hot polymer to said first polymer supply manifold continuously;
• (7) a second polymer plasticizer connected to the input of said second polymer supply manifold and adapted to supply a second hot polymer to said second polymer supply manifold continuously;
• (8) a third polymer plasticizer connected to the input of said third polymer supply manifold and adapted to supply a third hot polymer to said third polymer supply manifold continuously;
• and
• (9) respective heating means for maintaining the respective polymers at their respective working temperatures during their passage from the respective plasticizers to the respective injection molding cavities;
• whereby in each said module, said first hot polymer is supplied by respective injectors to said outer ports in said co-injection nozzle, said second hot polymer is supplied by respective injectors to said intermediate ports in said co-injection nozzle, and said third hot polymer is supplied by one said injector to said central port in said injection nozzle.