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AssigneeNone recorded
InventorBruce V. Weeks
Estimating the term…
A production method is disclosed for separating integrally attached gutter flash from a blow-molded thermoplastic resin product utilizing tensile forces applied to the gutter flash while the product is fully restrained within the closed co-operating product mold in which the product is formed, as well as different embodiments of apparatus suitable for accomplishing the production method in a conventional industrial blow-molding machine.
In a method of producing a blow-molded thermoplastic resin product that is contained within operationally-closed co-operating blow-mold subassemblies having movable sectional gutter portions which form the product with a product mold parting line perimeter and with gutter flash integrally attached to the product at the product mold parting line perimeter, the step of progressively separating the integrally attached gutter flash from the product by moving one or more of the sectional gutter portions of the mold at the product mold parting line perimeter while restraining the product within the operationally-closed co-operating blow-mold sub-assemblies.
In a method of producing a blow-molded thermoplastic resin product in blow-mold apparatus having co-operating blow-mold sub-assemblies having movable sectional gutter portions which are each provided with a complementary product cavity, the steps of:
In a method of producing a blow-molded thermoplastic resin product in co-operating base and cap blow-mold sub-assemblies which each have a product mold and a relatively movable gutter plate that surrounds the product mold, the step sequence of:
In a method of producing a blow-molded thermoplastic resin product in co-operating base and cap blow-mold sub-assemblies which each have a liquid-cooled product mold and a relatively movable liquid-cooled gutter plate that surrounds the product mold, the step sequence of:
In a method of producing a blow-molded thermoplastic resin product in co-operating base and cap blow-mold sub-assemblies which each have a product mold and a movable gutter plate surrounding the product mold, and which each function to form the blow-molded thermoplastic resin product with a blow-mold parting line perimeter, with a gutter flash tapered transition tab integrally attached to the blow-molded product along the product blow-mold parting line perimeter, and with non-tapered gutter flash integrally attached to the gutter flash tapered transition tab, the steps of:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Opening, closing or clamping means: hydraulically operated, i.e. closing or opening of the mould parts is done by hydraulic means
Component parts, details, accessories or auxiliary operations, not covered by group B29C33/00 or B29C35/00: deburring or deflashing
Characterised by the shape of the extruded material at extrusion: flat, e.g. panels
Characterised by the shape of the extruded material at extrusion: articles with cross-sections having partially or fully enclosed cavities, e.g.…
Term ended 30 Jul 2021 (estimated)
None.
The present invention relates generally to the manufacture of blow-molded thermoplastic products, and particularly concerns both a method and apparatus for accomplishing the separation of integrally formed gutter flash from a blow-molded product while the product is completely restrained by the product mold cavity of the apparatus.
It is common practice in the United States in connection with the manufacture of blow-molded thermoplastic resin products using conventional production blow-molding machines and known blow-mold assemblies to eject the molded product from the mold assembly with the simultaneously formed gutter flash integrally attached, and to afterwards completely separate the integrally attached flash from the ejected blow-molded product by subsequent combined operations such as sequential cutting and grinding or sequential shearing and grinding. The operating forces required to so-separate and remove such flash, either manually or by machine, sometimes are extremely large and often are beyond the available capacity of the blow-molding machine. The required flash separation and removal forces are especially substantial in cases where the blow-molding machine production cycle unit output is comprised of a single blow-molded product or multiple blow-molded products, each with integrally attached gutter flash, having either or both a substantial resin material wall thickness and a substantial total length of gutter flash trim edge.
FIG. 1 is a schematic perspective view of a conventional production blow-molding machine within which the methods and apparatus of the present invention may be practiced;
FIG. 2 is a schematic elevation view of the interior of the blow-molding machine of FIG. 1 illustrating the mold sub-assemblies of the present invention in a fully separated condition;
FIG. 3 is similar to FIG. 2 except that the included invention mold sub-assemblies are illustrated in an operationally closed condition;
The method of the present invention involves a basic step sequence of blow-molding an extruded and heated thermoplastic resin parison contained within co-operating blow-mold sub-assemblies to form a blow-molded product with integrally attached gutter flash, separating the integrally attached gutter flash from the blow-molded product progressively along the product mold parting-line perimeter from one product dimensional limit to an opposite dimensional limit until flash separation is, depending essentially on product geometry and overall dimensional size, completed or very-nearly completed, and afterwards separating the closed blow-mold sub-assemblies for purposes of accomplishing removal of the product and separated gutter flash from the blow-mold apparatus. The forces applied to the gutter flash during such progressive gutter flash separation are essentially tension forces rather than conventional cutting or shear forces. One embodiment of the invention apparatus particularly well-suited for the production of multiple units of a relatively small, blow-molded product in one complete operating cycle of a conventional industrial blow-molding machine is detailed in FIGS. 1 through 24 of the drawings. Another embodiment of the apparatus of the present invention, an embodiment particularly well-suited for the production of a single unit of a relatively large, blow-molded product in one complete operating cycle of the conventional industrial blow-molding machine is detailed in FIGS. 25 through 31.
FIGS. 1 through 4 schematically illustrate a conventional industrial blow molding machine 10, such as the large-size either SE or SL Series “Sterling” blow molding system manufactured and marketed by Davis-Standard Corporation of Edison N.J., customized to include the blow-mold assemblies utilized in the practice of the present invention. Such machine generally has a throat size that ranges from 38 inches by 36 inches to 84 inches by 60 inches, and is especially well adapted to the production in each machine cycle of either a single very large blow-molded product or multiple smaller-sized blow-molded products utilizing, in either case, an extremely short production cycle time generally varying from approximately 45 to 60 seconds per cycle. Production rates for machine 10 typically varies in the range from 60 to 480 or more units of blow-molded product per hour, depending upon product dimensional size. Such machine is capable of blow-molding a variety of different thermoplastic resins including polyolefin resins and other resins such as polycarbonate, polyethylene, polyvinylchloride, and like resins that are technically-formulated for use in blow-molding applications.
Machine 10 typically includes the illustrated feedstock hopper 12, a feed screw feedstock conveyor 14, and a conventional melter-accumulator-extruder sub-assembly 16 with variably-controlled parison die head 18. Machine 10 also includes guideposts 19 upon which movable platens 20 and 24 reciprocate. Movable machine platen 20 carries base blow-mold sub-assembly 22 and movable machine platen 24 carries cap blow-mold sub-assembly 26. Although such base and cap blow-mold sub-assemblies have co-operating complementary product-forming cavities and generally similar constructions, their respective total function differs.