US 5,635,117 AGranted

Injection molding technique for plural cavity products

AssigneeMazda Motor Corporation

InventorsYoshikazu Fujioka, Nobutaka Tanaka, Yasuyuki Kan

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Abstract

An injection molded product including a plurality of internal cavities is produced by, after having injected a molten resin material into the molding cavity, injecting an inert gas with a gas pressure gradually increasing into the resin material through gas injection nozzles, which are in contact with the resin material to form the respective internal cavities inside the molten resin material. After removing the gas injection nozzles from the resin material for discharging of the inert gas directly from the resin material, any one of the gas injection nozzles, whose temperature during injection of the inert gas was lower than a predetermined temperature level, is judged to be clogged and the gas injection nozzle is cleaned by being blown out with high pressure gas.

Claims10

Dependent claims

A method of producing a molded product, having a plurality of internal cavities, from a molten resin material in a molding cavity comprising the steps of:

bringing a plurality of gas injection nozzles into contact with said molten resin material;
injecting an inert gas into the molten resin material in the molding cavity through said plurality of gas injection nozzles so that each of the gas injection nozzles forms one of said internal cavities inside of said molten resin material;
gradually increasing a gas pressure of said inert gas supplied to said plurality of internal cavities through said gas injection nozzles so as to further form said plurality of internal cavities inside of said molten resin material;
removing said gas injection nozzles from said resin material after a predetermined time so that said inert gas is discharged from said plurality of internal cavities;
detecting a temperature of each of said gas injection nozzles;
judging the molded product to be properly produced with a specified quality when each temperature detected is lower than a predetermined temperature;
supplying a pressurized gas through at least one of said gas injection nozzles after removing said at least one of said gas injection nozzles from said resin material when the temperature of the at least one of said gas injection nozzles is higher than said predetermined temperature;
bringing said at least one of said gas injection nozzles again into contact with said resin material in said molding cavity;
and
injecting inert gas into said resin material so as to form an internal cavity in said resin material.

7 more elements

A method of producing a molded product, having a plurality of internal cavities, from a molten resin material in a molding cavity comprising the steps of:

bringing a plurality of gas injection nozzles into contact with said molten resin material;
injecting an inert gas into the molten resin material in the molding cavity through said plurality of gas injection nozzles so that each of the gas injection nozzles forms one of said internal cavities inside of said molten resin material;
gradually increasing a gas pressure of said inert gas supplied to said plurality of internal cavities through said gas injection nozzles so as to further form said plurality of internal cavities inside of said molten resin material;
removing said gas injection nozzles from said resin material after a predetermined time so that said inert gas is discharged from said plurality of internal cavities;
detecting a temperature of each of said gas injection nozzles;
and
judging the internal cavities of the molded product to be properly produced with a specified quality when each temperature detected is lower than a predetermined temperature;
wherein the temperature of each of the gas injection nozzles is detected while injecting said inert gas.

5 more elements

Dependencies are inferred from the claim text.