Method of molding preform in injection stretch blow molding
AssigneeA.K. Technical Laboratory, Inc.
InventorsHisashi Nakajima, Hideaki Koda
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Abstract
A method of molding a preform in an injection stretch blow molding, wherein a gas is entered into the boundary between the preform and an injection core so that the gas pressure causes the preform in an injection mold to be insulated from the injection core, thereby allowing a high-temperature releasing of the preform.
Claims11
In a method of injection stretch blow molding wherein an injection molded preform is released in a high temperature state from an injection mold and an injection core while being held by a neck mold, and the released preform is stretch blow molded to a molded product immediately after the injection molded preform is released the improvement which comprises the steps of
- forcing a gas having a predetermined pressure into the boundary between the preform formed by injecting a resin in an injection cavity and the injection core so that the gas pressure causes an inner surface of the preform to be insulated from a surface of the injection core and the preform to be urged against the cavity surface, thereby performing a cooling step for producing a skin layer on the high temperature preform;
- and
- releasing the preform from the injection mold in a state where the inner surface of the preform is insulated from the surface of the injection core.
A method of injection stretch blow molding comprising the steps of:
- injection molding a predetermined preform by filling an injection mold comprising a cavity die, a core die and a neck mold with molten molding resin,
- forcing a gas having a predetermined pressure into the boundary between the preform and the injection core so that the gas pressure causes the inner surface of the preform to be insulated from the surface of the injection core and the preform to be urged against the cavity surface, thereby performing a cooling step for producing a skin layer on the high temperature preform,
- releasing the preform in a high temperature state from the injection mold while the preform is in a state where the inner surface of the preform is insulated from the surface of the injection core, and while the preform is being held by the neck mold, and
- immediately after the injection molded preform is released, biaxially stretching and expanding the preform employing a stretching rod and blowing air into the form of a hollow thin-walled product.
Dependencies are inferred from the claim text.