Thread forming and neck finishing process
AssigneeHercules Incorporated
InventorRichard Webster Legrand
Life of this patent
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Abstract
The invention is a process for biaxially blow molding hollow plastic articles to provide a finished neck of axially oriented material in the molding step. One end of a plastic parison is placed over a blow pin positioned between separable mold halves. The parison is then axially oriented and necked down over said blow pin. A crammer sleeve is positioned over the blow pin to cram axially oriented material into the neck finishing cavities when the molds are closed over said blow pin and parison.
Claims3
A process for biaxially blow molding hollow plastic articles to provide a finished neck of axially oriented material comprising:
- a. heating a parison of partially crystalline orientable material to just below the material's crystalline melting point;
- b. placing one end of said parison over a blow pin;
- c. clamping said one end of said parison over and radially spaced from said blow pin;
- d. axially stretching and orienting said parison, thereby drawing said one end of said parison down against said blow pin and reducing the thickness of said parison to a first wall thickness over said blow pin;
- e. further stretching the free portion of said parison to a second wall thickness, said second wall thickness being thinner than said first wall thickness;
- f. clamping mold means around said parison, said mold means having neck finishing cavities contained therein in the portion of said mold means surrounding said blow pin;
- g. axially moving an inner portion of the parison in the clamped end of said parison toward said mold means, thereby forcing a portion of said oriented parison into the neck finishing cavities forming a finished neck;
- and
- h. introducing blow air via the blow pin to radially expand the portion of said parison having said second wall thickness producing a biaxially oriented container body.
A process for biaxially blow molding hollow plastic articles to provide a finished neck of axially oriented material comprising:
- a. heating a parison of partially crystalline orientable material to just below the material's crystalline melting point;
- b. placing one end of said parison over a blow pin;
- c. clamping said one end of said parison over and radially spaced from said blow pin;
- d. axially stretching and orienting said parison, thereby drawing said one end of said parison down against said blow pin and reducing the thickness of said parison to a first wall thickness over said blow pin;
- e. further stretching the free portion of said parison to a second wall thickness, said second wall thickness being thinner than said first wall thickness;
- f. clamping mold means around said parison, said mold means having neck finishing cavities contained therein in the portion of said mold means surrounding said blow pin;
- g. introducing blow air via the blow pin to radially expand the portion of said parison having said second wall thickness producing a biaxially oriented container body;
- and then
- h. axially moving an inner portion of the parison in the clamped end of said parison toward said mold means thereby forcing a portion of said oriented parison into the neck finishing cavities forming a finished neck.
Dependencies are inferred from the claim text.