Paperboard Servingware Rim Structure for Higher Rigidity
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Solution Overview
Problem
Pressed paperboard containers exhibit less strength and rigidity compared to pulp molded containers due to seams or pleats formed during the pressing process, which act as material weaknesses and reduce their load-carrying ability.
Innovation Solution
Incorporating a press-formed transition and an outwardly extending evert at the rim of paperboard containers, with a brim transition portion that transitions to an annular evert portion at an eversion angle of at least 25 degrees, helps to fortify the rim and lock pleats in place, enhancing rigidity and rim stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pressed paperboard containers are formed using conventional pressing processes, then manufacturing efficiency is maintained, but seams or pleats are created that reduce strength and rigidity
Solution Approach 1:
The patent applies preliminary action by pre-scoring the paperboard blank along radial lines before pressing. These scores create controlled weak points that allow the material to flex and form pleats without creating uncontrolled seams. The scoring is done in advance so that during pressing, the paperboard follows the predetermined score lines, transforming potential weaknesses into controlled structural features that maintain strength while enabling formation.
Solution Approach 2:
The patent changes physical parameters of the paperboard by controlling the scoring depth, angle, and pattern. By adjusting these parameters, the paperboard's flexibility and bond strength at the pleat locations are optimized. The scores are made deep enough to allow folding but not so deep as to create weak points, transforming the material properties locally to resolve the contradiction between formability and strength.
2Strength
If the rim structure is simplified for ease of manufacture, then production efficiency is improved, but rigidity and rim stiffness are reduced
Solution Approach 1:
The patent segments the brim structure into distinct functional portions: a downwardly extending brim portion and an outwardly extending evert portion. This segmentation allows each portion to be optimized independently - the downward brim provides basic structural support while the evert portion specifically addresses rim stiffness requirements. The segmentation transforms a single complex curved surface into manageable geometric segments that are easier to manufacture while achieving superior rim performance.
Solution Approach 2:
The patent adds a second dimensional component to the rim structure by introducing the evert portion that extends outwardly perpendicular to the downward brim portion. This creates a three-dimensional L-shaped rim profile that significantly increases rim stiffness without requiring excessive brim height or complex curvature. The dimensional change from a simple curved brim to an L-shaped profile with both vertical and horizontal components provides enhanced structural performance.
Data Source
AI summary
Products and methods of increasing the Rigidity and Rim Stiffness of disposable containers are provided. The containers have an outer flange portion extending outwardly with a brim portion sloping downwardly defining a declivity angle α with respect to a horizontal generally parallel to the bottom portion and generally include an outward turn at the periphery of the container. A preferred method of improving rigidity includes press-forming: (i) a brim transition portion adjoining the downwardly sloping brim portion of the container and (ii) an outwardly extending annular evert portion adjoining the brim transition portion extending outwardly at an eversion angle β of at least about 25 degrees with respect to the downwardly sloping brim portion of the flange.