Freestanding container with improved combination of properties
First Claim
1. A freestanding container having an improved combination of strength, stability and formability, the container being a hollow molded plastic body including a substantially cylindrical sidewall defined by a vertical centerline and having a radius R, and an integral base, the base including a bottom wall with a plurality of radial ribs, and legs extending downwardly from the bottom wall between the ribs and each terminating in a lowermost supporting foot, the improvement comprising:
- the bottom wall being a continuous smooth surface free of stress concentrations and being substantially hemispherical with four radial ribs symmetrically positioned about the vertical centerline, each rib having a rib wall which is part of the substantially hemispherical bottom wall and having an average angular extent of from about 15°
to about 30°
to provide enhanced strength;
each leg occupying the remaining angular extent between each rib wall of from about 75°
to about 60°
to provide enhanced formability; and
each foot having an outer edge radially disposed a distance LF of at least about 0.60R from the vertical centerline and an angular extent DF of from about 12°
to about 40°
to provide enhanced stability.
11 Assignments
0 Petitions
Accused Products
Abstract
A freestanding container base having an improved combination of properties in regard to creep resistance, stress crack resistance, impact strength, weight, standing stability and formability. The container base has a substantially hemispherical bottom wall which includes four radiating ribs, and four legs extending downwardly from the bottom wall between the ribs and each of which terminates in a foot. Each rib has a rib wall forming part of the substantially hemispherical bottom wall and having an angular extent of from about 15° to about 30° for enhanced strength, with the leg occupying the remaining 75° to 60° angular extent for enhanced formability. The outer edge and angular extent of the foot are predetermined for enhanced stability and ease of formability. Preferably, the creep resistance is further enhanced by straightening the upper rib portion or providing an enlarged-diameter truncated bottom wall. The base is particularly suited for a blown PET carbonated beverage bottle.
123 Citations
32 Claims
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1. A freestanding container having an improved combination of strength, stability and formability, the container being a hollow molded plastic body including a substantially cylindrical sidewall defined by a vertical centerline and having a radius R, and an integral base, the base including a bottom wall with a plurality of radial ribs, and legs extending downwardly from the bottom wall between the ribs and each terminating in a lowermost supporting foot, the improvement comprising:
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the bottom wall being a continuous smooth surface free of stress concentrations and being substantially hemispherical with four radial ribs symmetrically positioned about the vertical centerline, each rib having a rib wall which is part of the substantially hemispherical bottom wall and having an average angular extent of from about 15°
to about 30°
to provide enhanced strength;each leg occupying the remaining angular extent between each rib wall of from about 75°
to about 60°
to provide enhanced formability; andeach foot having an outer edge radially disposed a distance LF of at least about 0.60R from the vertical centerline and an angular extent DF of from about 12°
to about 40°
to provide enhanced stability. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A container comprising:
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a hollow plastic blow-molded body having an open top end, a substantially cylindrical sidewall, and a closed integral base, the sidewall being defined by a vertical centerline and a radius R; the base having a continuous and smooth bottom wall free of stress concentrations and being substantially hemispherical with four radiating ribs symmetrically positioned about the vertical centerline, and four legs extending downwardly from the bottom wall between the ribs and each terminating in a lowermost supporting foot; each rib having a rib wall which is part of the substantially hemispherical bottom wall and having an average angular extent of from about 15°
to about 30°
;each leg occupying the remaining angular extent between each rib wall of from about 75°
to about 60°
;each foot having an outer edge radially disposed a distance LF of from about 0.60R to about 0.80R from the vertical centerline;
each foot having an angular extent DF of from about 12°
to about 40°
;each foot having a radial width WF between an amount sufficient to establish line contact and up to about 0.35R; the bottom wall having a lowermost central point disposed at a distance HD above a common plane on which the feet reside of from about 0.08R to about 0.20R; and each leg having an inner leg wall extending between an innermost radial edge of the foot and a central portion of the bottom wall, the inner leg wall being a continuous and substantially smooth surface which is upwardly inclined at an acute angle to a common plane on which the feet reside.
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28. A method of making a freestanding container base having an improved combination of strength, stability and formability, the container being a hollow blow-molded plastic body including a substantially cylindrical sidewall defined by a vertical centerline and having a radius R, and an integral base, the base including a bottom wall with a plurality of radial ribs, and legs extending downwardly from the bottom wall between the ribs and each terminating in a lowermost supporting foot, the method comprising the steps of:
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providing the base with a substantially hemispherical bottom wall, the bottom wall being a continuous smooth surface free of stress concentrations; providing four ribs and placing each of the four ribs in a separate quadrant of the bottom wall to form four symmetrical ribs about the vertical centerline, each rib having a rib wall which is part of the substantially hemispherical bottom wall and having an average angular extent of from about 15°
to about 30°
to provide enhanced strength;providing a leg between each rib wall to occupy the remaining angular extent of from about 75°
to about 60°
to provide enhanced formability; andproviding a foot having an outer edge radially disposed a distance LF of from about 0.60R to about 0.80R from the vertical centerline and an angular extent DF of from about 12°
to about 40°
to provide enhanced stability. - View Dependent Claims (29, 30, 31, 32)
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Specification