Arched Bottom Panel Press-Formed Paperboard Servingware
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Solution Overview
Problem
Existing disposable paperboard serving containers, such as plates and bowls, face challenges with stiffness and load-bearing capability due to flat or concave bottoms, which lead to rocking issues and limited strength, especially when compared to pulp molded or plastic alternatives.
Innovation Solution
The development of disposable servingware containers with a bottom panel featuring an arched central crown and specific transition radii, including a first annular transition portion and a second annular transition portion with a small radius of curvature, enhancing the container's stiffness and durability without requiring additional material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a flat or concave bottom panel is used in pressware containers, then manufacturing is simple, but the container exhibits rocking behavior and limited stiffness
Solution Approach 1:
The bottom panel is formed with an arched crown geometry featuring a convex upper surface that spans approximately 75% of the horizontal distance from the center to the first annular transition portion. This curvature creates a stable, non-rocking base while distributing loads more effectively across the container structure.
Solution Approach 2:
The bottom panel is divided into distinct functional zones: an arched central crown region for stability, a first annular transition portion with radius R1 connecting to the sidewall, and a second annular transition portion with a sharp brim transition radius R2 (where R2/R1 ≤ 0.25). This segmentation allows each region to perform its specific structural function optimally.
2Strength
If additional material is used to increase container strength, then load-bearing capability improves, but material cost and waste increase
Solution Approach 1:
The invention optimizes geometric parameters including the arched crown height (h/D = 0.02 to 0.08), the radius ratio (R2/R1 ≤ 0.25), and the span of the arch (approximately 75% of horizontal distance). These parameter changes maximize structural efficiency, achieving higher strength-to-material ratios compared to conventional flat-bottom containers.
Solution Approach 2:
The bottom panel transitions from a two-dimensional flat surface to a three-dimensional arched structure with convex curvature. This dimensional change adds structural rigidity and load-bearing capacity without proportionally increasing material consumption, as the arch shape distributes forces more efficiently throughout the container walls.
3Strength
If a sharp brim transition with small radius R2 is implemented, then rim stiffness and overall container rigidity increase, but manufacturing precision requirements increase
Solution Approach 1:
The invention specifies that the ratio R2/R1 should be ≤ 0.25, with preferred embodiments having R2/R1 ≤ 0.15. This parameter relationship provides a design guideline that balances rim stiffness with manufacturability, ensuring the sharp brim transition provides adequate structural reinforcement while remaining feasible with standard pressware forming equipment.
Data Source
AI summary
A disposable servingware container 10 press-formed from a generally planar paperboard blank has a characteristic diameter, D, and includes a bottom panel 12 having an arched central crown 14 with a convex upper surface 14a, a first annular transition portion 16 extending upwardly and outwardly from the bottom panel, with the proviso that a portion of the arched central crown defines a substantially continuous, convex arched profile 18 spanning at least 75% of the horizontal distance between center 20 of the container and the first annular transition. An optional sidewall portion 26 extends upwardly and outwardly from the first annular transition portion, while a second annular transition portion 28 flares outwardly with respect to the first annular transition portion defining a second radius of curvature, R2. The ratio of R2/D is 0.0125 or less. An outer flange portion 32 extends outwardly with respect to the second annular transition portion and forms the outer perimeter of the container.