Polygonal Plastic Container Bottom with Variable Radius Fillet
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Solution Overview
Problem
Stackable containers with polygonal sections face issues with flatness defects in the laying plane due to asymmetry, leading to instability under axial compressive forces, and existing solutions like boxing do not fully address these problems while maintaining the preferred polygonal shape for stacking.
Innovation Solution
A container design with a polygonal section featuring a variable radius fillet connecting the annular seat to the central pin, where the radius is minimum at vertices and maximum at sides, enhancing blowability and mechanical resistance to compression forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polygonal section is used for stackable containers, then mechanical resistance to buckling under axial compression is improved, but flatness defects in the laying plane occur due to asymmetry
Solution Approach 1:
The patent applies local quality by varying the fillet radius at different locations of the bottom. The fillet connecting the central pin to the annular seat has a maximum radius in sectors delimited by vertices and a minimum radius in sectors delimited by sides. This local variation compensates for the asymmetry of the polygonal section, enabling uniform material distribution and correct mold imprinting across all areas, thereby achieving a flat laying plane while maintaining the polygonal shape for stacking resistance.
2Ease of manufacture
If boxing is used to improve bottom forming, then ease of forming is improved, but flatness of the laying plane is not perfectly achieved
Solution Approach 1:
The patent applies parameter changes by modifying the geometry of the bottom, specifically the fillet radius connecting the central pin to the annular seat. The fillet radius varies angularly around the main axis, with maximum values at vertex sectors and minimum values at side sectors. This geometric parameter variation improves material flow and mold imprinting during the boxing process, achieving a flat laying plane that combines the benefits of boxing with enhanced precision.
Data Source
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Figure 3
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AI summary
A plastics container (1) includes a body (2) with a polygonal section which extends along a main axis (X), a shoulder (4) which extends in continuation of the body (2) on an upper side, a neck (5) which extends in continuation of the shoulder (4), and a bottom (3) which extends in continuation of the body (2) on a lower side, the bottom (3) including: an annular seat (9) defining a standing perimeter (10), having a polygonal contour formed from a plurality of sides and vertices, and approximately perpendicular to the main axis (X); a central peg (16) having a side wall (17) that has a generally axisymmetric frustoconical shape about the main axis (X) and which is connected to the rest of the bottom (3) by a connecting fillet (19) which has a radius that is variable in revolution about the main axis (X) of the container.