Gas-assisted injection molding apparatus

A mold for use in gas-assisted injection molding of a thermoplastic article, the mold comprising:

• a cavity defining the shape of a thermoplastic article;
• at least one thermoplastic entry aperture which is adapted to receive molten thermoplastic resin from a nozzle of an injection molding machine;
• a thermoplastic flow path in fluid communication with the thermoplastic entry aperture and with the cavity;
• a fluid flow passageway extending from an exterior surface of the mold to the cavity for communicating a lower viscosity fluid to the cavity, the fluid flow passageway being spaced laterally from and separate from the thermoplastic flow path;
• a plug mounted in an end portion of the fluid flow passageway adjacent the cavity, the plug comprising a porous core which is adapted to permit the flow of low viscosity fluid therethrough but prevent the passage of thermoplastic therethrough;
• and
• a source of fluid pressure connected to the fluid flow passageway to supply a low viscosity fluid under pressure to the mold cavity through the fluid flow passageway.

A mold for use in the gas-assisted injection molding of a thermoplastic article, the mold comprising:

• a cavity defining the shape of a thermoplastic article;
• at least one thermoplastic entry aperture which is adapted to receive molten thermoplastic resin from a nozzle of an injection molding machine;
• a thermoplastic flow path in fluid communication with the thermoplastic entry aperture and with the cavity;
• a fluid flow passageway extending from an exterior surface of the mold to the thermoplastic flow path for communicating a low viscosity fluid to the thermoplastic flow path;
• a source of low viscosity fluid under pressure connected to the fluid flow passageway to supply a low viscosity fluid under pressure to the mold cavity through the fluid flow passageway;
• and
• a plug disposed in an end portion of the fluid flow passageway with the end of the plug substantially flush with the walls of the mold defining the thermoplastic flow path, the plug comprising a porous core which is adapted to permit the flow of low viscosity fluid therethrough but prevent the passage of molten thermoplastic therethrough.

A mold for use in the gas-assisted injection molding of a thermoplastic article, the mold comprising:

• a cavity defining the shape of a thermoplastic article;
• at least one thermoplastic entry aperture which is adapted to receive molten thermoplastic resin from a nozzle of an injection molding machine;
• a thermoplastic flow path in fluid communication with the thermoplastic entry aperture and with the cavity;
• a fluid flow passageway extending from an exterior surface of the mold to the thermoplastic flow path for communicating a low viscosity fluid to the thermoplastic flow path;
• a plug disposed in an end portion of the fluid flow passageway adjacent the thermoplastic flow path, the plug comprising a porous core which is adapted to permit the flow of low viscosity fluid therethrough but prevent the passage of molten thermoplastic therethrough;
• a selectively rotatable cylinder which is closed at its forward end with a cap, wherein the fluid flow passageway extends through the cylinder, the cap extends into the thermoplastic flow path and the cap has an opening which defines an outlet for the fluid flow passageway, whereby the outlet is adapted to face different directions within the thermoplastic flow path upon selective rotation of the cylinder to thereby permit directional control of the fluid injection into the thermoplastic flow path.

A mold for use in gas-assisted injection molding of a thermoplastic article, the mold comprising:

• a cavity defining the shape of a thermoplastic article;
• at least one thermoplastic entry aperture which is adapted to receive molten thermoplastic rein from a nozzle of an injection molding machine;
• a thermoplastic flow path in fluid communication with the thermoplastic entry aperture and with the cavity;
• a fluid flow passageway extending from an exterior surface of the mold to the cavity for communicating a lower viscosity fluid to the cavity;
• a plug immovably mounted in the end of the fluid flow passageway with an end of said plug substantially flush with adjacent walls of the mold and forming a part of the cavity, the plug comprising a porous core which is adapted to permit the flow of low viscosity fluid therethrough but prevent the passage of thermoplastic therethrough;
• and
• a source of fluid pressure connected to the fluid flow passageway to supply a low viscosity fluid under pressure to the mold cavity through the fluid flow passageway.