Method for forming hollow plastic products and device therefor

Abstract

The present invention relates to hollow plastic product forming process and device, and is especially gas assisted injection forming process for producing sheet type plastic product with structural rib board and the device, controllable flash chamber. The forming process includes at least: injecting molten plastic into inner cavity of mold, further injecting after filling the inner cavity to pressurize, controlling the piston of the flash chamber to withdraw some interval, introducing pressurizing gas to the molten plastic inside the cavity, pushing the molten plastic with the screw of the plastic injecting machine into the controllable flash chamber, controlling the gas pressure and piston shift to make gas enter to the relatively thick part inside the mold cavity, cooling plastic inside the mold cavity while controlling the piston shift, and making gas flow into inside of the plastic product to speed cooling. The present invention has the advantages of no shrinkage and crack in the thicker part of the product, high production efficiency, etc.

Description

technical field [0001] The present invention relates to a method for forming hollow plastic products and related devices, in particular to a method for producing thin-plate plastic products containing structural ribs using gas-assisted injection molding technology and related devices—controllable overflow cavity. technical background [0002] Ernst Friederich of Rohm GmbH in Germany was the first to invent the gas-assisted injection molding process. The patent No. 2501314 disclosed in German patent literature in 1975 is a molding method for making thermoplastics into hollow products by injection molding. The method disclosed in this patent literature includes injecting sufficient molten material into the prepared above-mentioned In the mold of the hollow product, the pressurized gas is also injected into the molten material through the hole on the nozzle to make the molten material fully contact with the inner surface of the mold. Then, in the above-mentioned mold, the hol...

AI Technical Summary

Problems solved by technology

Since the volume of the melt discharged before testing and molding cannot be accurately calculated

Therefore, it is necessary to repeatedly adjust the volume of the overflow cavity after the initial or subsequent model inspection test, which brings great inconvenience to the mold processing, and the change of the plastic material, the level of the melt temperature in the process, and the change of the molding machine parameters , the temperature of the cavity, the interval between the discharge start time of the gas pushing the molten plastic in the thicker position of the cavity and the injection time of the plastic, and the length of the discharge time all affect the amount of the discharge material, that is, the volume of the overflow cavity. The connection between the flow cavity and the cavity is connected through a small channel. The general control valve device is composed of a small plunger that cuts off the small channel, its control device, and the control system. The control part can move the position of the small plunger to control the small channel. In the production process, the plastic melt forms a solidified layer a

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