Method and apparatus for injection blow molding an article with improved detail definition
AssigneeHercules Incorporated
InventorAime J. Gendron
Life of this patent
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Abstract
An injection blow molding apparatus and method produces articles by injecting a settable material at high pressure into the cavity of an injection mold to form a parison and then expanding the parison in a blow mold defining the configuration of the article. The injection mold defines intricate detail in the walls of the injection cavity and produces a parison with the detail formed thereon. Detail on the expanded portion of the parison is preserved in the blow mold and appears on the surface of the blown article without loss of definition.
Claims8
A method of molding an article with molding detail of high definition in an injection blow molding machine having an injection mold and cooperating blow mold comprising:
- providing in the molding cavity of the injection mold features recessed below the surrounding cavity wall and defining molding detail finer than that obtainable in the blow mold under preselected blowing pressures and temperatures;
- injecting settable material into the injection mold cavity at injection pressures and temperatures sufficiently elevated to force the settable material into the recessed features of the mold cavity and thereby produce a parison having the features of finer molding detail raised thereon;
- transferring the parison with the molding features thereon from the cavity of the injection mold to the cavity of the blow mold;
- blowing the parison in the cavity of the blow mold under the preselected blowing pressures and temperatures to form an article having the general shape defined by the blow mold cavity;
- and
- during the step of blowing preserving the features of finer molding detail raised on the parison by limiting the level of the preselected blowing pressures and temperatures to prevent the raised detail from being deformed by the blow cavity wall.
In a method of molding a hollow article in an injection blow molding machine having an injection mold for forming a parison in an injection step and an associated blow mold for expanding the parison into the shape of the hollow article in a blowing step, the improvement comprising:
- forming intricate detail on the exterior surface of the expandable portion of the parison during the injection step by providing corresponding recesses in the wall of the injection mold, the detail being raised from the surrounding surface by a limited amount and of a scale substantially smaller than the general contours of the parison;
- and
- retaining said intricate detail on the expanded portion of the parison during the step of blowing to produce the hollow article with the intricate detail thereon by providing in the wall of the blow mold a recess accommodating the raised detail as the surrounding exterior surface of the parison is expanded against the mold wall.
Dependencies are inferred from the claim text.