Corrugated Container Base for Low-Pressure rPET Stability
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Solution Overview
Problem
Containers made from recycled PET (rPET) with traditional reinforced bases are not able to withstand low internal pressures generated by inerting processes without deformation, and reducing material weight compromises their structural integrity, making them unsuitable for holding flat liquids under varying pressures.
Innovation Solution
A container design featuring a base with radial undulations that increase in depth from the central zone to the periphery, combined with a concave vault and a connecting wall, enhances structural strength while minimizing material use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional reinforced bases are used to withstand inerting pressure, then structural strength is improved, but material weight increases
Solution Approach 1:
The base is designed with a domed configuration featuring radial undulations (crests and troughs) that create curved surfaces. These spherical/curved geometries naturally distribute and resist inerting pressure more effectively than flat surfaces, allowing the base to maintain structural strength with reduced material thickness and weight.
Solution Approach 2:
The base surface is segmented into multiple radial undulations consisting of alternating crests and troughs. This segmentation creates a series of radial ribs that reinforce the base structure, distributing stress across multiple zones rather than requiring a uniformly thick base, thereby reducing overall material usage while maintaining strength.
2Productivity
If material weight is reduced to lower production costs, then manufacturing efficiency is improved, but resistance to inerting pressure deteriorates
Solution Approach 1:
The domed base configuration with radial undulations creates curved surfaces that are inherently stronger at resisting pressure. The curvature distributes inerting pressure across the entire base surface, allowing thinner walls and reduced material weight while maintaining sufficient pressure resistance for reliable container performance.
Solution Approach 2:
The base features localized reinforcement through radial undulations with varying depths and profiles. The crests and troughs are strategically positioned to provide maximum structural support where needed, allowing material to be concentrated in high-stress areas while reducing material in lower-stress regions, optimizing both reliability and manufacturing efficiency.
3Strength
If radial undulations with increasing depth are implemented, then structural reinforcement is improved, but manufacturing complexity increases
Solution Approach 1:
The radial undulations are formed as continuous curved surfaces extending from the central zone to the peripheral zone. This spherical/curved geometry can be efficiently produced using standard blow molding techniques, avoiding the need for complex multi-step manufacturing processes while achieving the desired reinforcement effect through the undulated profile.
Solution Approach 2:
The mold base incorporates the radial undulation profile directly into its geometry, allowing the container base to be formed in a single blow molding operation. The dynamic flow of molten material naturally conforms to the mold's undulated surface, creating the reinforced structure without requiring secondary operations or assembly steps, thus managing complexity effectively.
Data Source
Figure 1
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Figure 4~5
AI summary
The present invention relates to a plastic container (1) having a body (5) and a base (6) extending from a lower end of the body, said body (5) comprising at its upper end a shoulder (4) and a neck (2), and the base (6) comprising at least one peripheral heel (7) defining a seat (8), and an arch (10) extending from a central zone (11) to said heel (7), said heel (7) rising on a connecting wall (9) with the wall of the body (5) of the container (1), notable in that said base (6) has a plurality of radial undulations (13) extending from at least the central zone (11) to near the seat (8), i.e.extending at the level of the vault (6), a corrugation being composed of a concave face (13a) and a convex face (13b) facing outwards, the depth, that is to say the distance between the crest of a convexity (13b) and the bottom of a concavity (13a) of said corrugations (13) increasing from the central zone (11) to near the base (8). Another object of the invention relates to a mold base (23) for the manufacture of such a container (1).