Paperboard Lid Corner Cutouts for Internal Tension Relief
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Solution Overview
Problem
Paperboard and cardboard containers face limitations in mechanical characteristics, particularly in maintaining structural integrity under stress and tension, especially at lid corners, which can lead to deterioration and manufacturing line issues.
Innovation Solution
Incorporating a reinforced lid corner design with a controlled preliminary weakening of the internal layer through a cutout shape, which releases tension and enhances structural integrity while minimizing manufacturing disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If reinforcement layers are accumulated to reinforce a lid corner, then the structural integrity is improved, but mechanical tensions within the corner structure increase leading to weakening or breakage
Solution Approach 1:
The lid corner is divided into multiple layers (first lid corner layer, second lid corner layer, third lid corner layer) with distinct functions. The internal layer is segmented with a cutout shape to reduce tension, while external layers provide reinforcement. This segmentation allows each layer to perform its specific function without creating conflicting mechanical tensions.
Solution Approach 2:
A cutout shape is removed from the internal layer at the lid corner, extracting material that would otherwise create tension when folded. This extracted portion is removed entirely, preventing the internal layer from generating tensile forces that could weaken or break the external reinforcement layers.
2Strength
If multiple reinforced layers are attached prior to forming the corner structure, then reinforcement is improved, but the radius of curvature difference creates tension without sliding capability
Solution Approach 1:
The internal layer with the cutout shape acts as an intermediary element between the external reinforcement layers. By removing material from this internal layer, it serves as a tension-relieving intermediary that prevents stress transfer from the folded corner to the external layers, allowing the reinforced structure to form without excessive tension.
3Strength
If material is cut out and removed from the internal layer to release tension, then structural integrity is improved, but manufacturing line speed is negatively impacted due to debris accumulation
Solution Approach 1:
The cutout shape is specifically designed with local quality features - its size, position, and geometry are optimized to provide the minimum necessary tension relief at the critical corner area while minimizing material removal. This localized approach maintains structural integrity without generating excessive debris that would impact manufacturing line speed.
Data Source
Figure 1A~2B
Figure 3A~3D
Figure 4A~5
AI summary
Examples include a container comprising a box, a lid and a lock. The lid comprises a top, a first flank and a second flank which intersect at a first corner segment comprising a first external and a first internal paperboard or cardboard layer connected along a first longitudinal fold line parallel to the first flank and along a second longitudinal fold line parallel to the second flank. The first internal layer comprises a first cutout shape. The first cutout shape is elongated along the first corner segment, terminates more than 0.5cm away from the first and second longitudinal fold lines, has a maximum total span, along the first and second flanks and in a plane parallel to the top, of at least 0.3mm, preferably of at least 2mm, and has a length of less than 90% and of more than 10% of a height of the first internal layer along the first corner segment.