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Title: Method of making a blown bottle having a ribbed interior surface
Claims: Having fully and completely disclosed and described my present invention, I claim: 1. The method of varying the wall thickness of a blown plastic article, comprising: 1. blowing a parison interiorly of a first blow mold cavity to a blown pre-form having a blown body portion surmounted by a neck, the blow mold cavity having concave grooves in a portion thereof corresponding to the blown body portion of the pre-form, the blown body portion having a plurality of convex exterior bulbous ribs located on a portion of the periphery thereof at the pre-form portions corresponding to the locations of greatest desired strength on the blown body portion of the final article, said bulbous ribs being formed by expansion of the parison into the concave grooves; and then 2. in a single blowing step, blowing the pre-form interiorly of a final blow mold, expanding the ribbed portions of the blown pre-form body to a lesser extent that the non-ribbed portion, and forming a blown plastic article having a smooth exterior surface and a ribbed interior surface in the region corresponding to the ribbed portion of the pre-form. 2. In a method of making a blown plastic container having integral reinforcing ribs on its interior wall surface, the steps of: 1. enclosing a blowable plastic parison within a pre-form mold cavity defined by mold wall surfaces having concave grooves therein; 2. expanding the blowable parison against the pre-form cavity wall surfaces and forming a blown pre-form having an outer wall surface pattern of outwardly directed bulbous projections formed by expansion of portions of the parison into the concave grooves; 3. enclosing the blown pre-form within a final blow mold cavity defined by smooth wall surfaces for forming a smooth outer configuration on the container; and 4. expanding the pre-form against the smooth final blow cavity wall surfaces (a) to form a final article having smooth exterior surfaces and (b) to convert the outwardly directed pre-form projections into concave portions separated by convex reinforcing ribs at the interior wall surface of the container. 3. In a method of forming a blown thermoplastic container having a region of both structural- and material-reinforcement, comprising the steps of: 1. enclosing a blowable plastic parison having a substantially uniform wall thickness within a pre-blow mold cavity defined by a mold wall surface including at least one region having a plurality of grooves; 2. inflating the blowable plastic parison against the pre-blow mold wall surface and forming a pre-form having a region of outwardly directed bulbous ribs formed by expansion of portions of the parison in the grooved pre-blow cavity region; 3. enclosing the pre-form within a final blow mold cavity defined by substantially smooth mold wall surfaces conforming to the outer configuration of a container; and 4. in a single blowing operation (a) inflating the pre-form into contact with the wall surfaces of the final blow mold, (b) stretching the ribbed portion of the pre-form to a lesser extent than the other expanded portions, (c) flattening the bulbous ribs to form a smooth outer wall configuration on the container, and (d) forming reinforcing ribs on the internal wall surface of the container. 4. In a method of forming a blown thermoplastic container having a reinforced region of both structural- and material-reinforcement, comprising the steps of: 1. enclosing a blowable plastic parison having a substantially uniform wall thickness within a pre-blow mold cavity defined by mold wall surfaces including a region having a plurality of concave grooves; 2. inflating the blowable plastic parison against the pre-blow mold wall surfaces and forming a pre-form having (a) a major wall with a thickness less than the thickness of the original blowable parison and (b) a plurality of integral, outwardly directed bulbous ribs having a thickness less than that of said major wall; 3. enclosing the pre-form within a final blow mold cavity defined in part by substantially smooth mold wall surfaces in the region corresponding to the bulbous ribs on the pre-form; and 4. in a single blowing operation (a) inflating and expanding the pre-form into contact with the mold surfaces of the final blow mold, (b) stretching the major wall of the pre-form to a greater extent than the ribbed portion, (c) flattening the bulbous ribs to form a smooth outer wall configuration on the container, and (d) forming two reinforcing ribs on the internal wall surface of the container from each previously existing bulbous rib. 5. The method as defined in claim 4, characterized in Step (4) by forming the major wall of the pre-form into a container wall which is less than the thickness of both of the reinforcing ribs and the portion of the container between said reinforcing ribs. 6. The method of forming a blown container as defined in claim 4, characterized by forming the reinforcing ribs in Step (4) (d) at locations on the interior of the container corresponding to the heels of the previously existing outwardly directed bulbous ribs. 7. The method of forming a blown thermoplastic container as defined in claim 4 characterized by Step (2) including the formation of bulbous ribs around less than the entire circumferential periphery of the pre-form, wherein the reinforcing ribs formed by Step (4) (d) extend around less than the entire inner periphery of the container. 8. The method of forming a blown thermoplastic container as defined in claim 4 characterized by Step (2) including the formation of sinuous shaped bulbous ribs which are converted into twice as many sinuous-shaped reinforcing ribs by Step (4) (d). Other info: Inventors: Uhlig, Albert R. (Toledo, OH, US) Application Number: 505966 Filing Date: 1974-09-16 Publication_date: 1976-05-11 Assignee: Owens-Illinois, Inc. (Toledo, OH) Primary Class(es): 264/530 264/296, 425/525, 425/530 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Silbaugh, Jan H. Assistant Examiner: Attorney: Rice; Philip M., Holler; E. J. |
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