Container Lid Liner With Localized Thickness Variation
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Solution Overview
Problem
Conventional container lids face issues where the radially inner region of the outer peripheral edge portion of the first layer is damaged during press-molding of the second layer, and the synthetic resin material fails to flow smoothly, leading to incomplete shaping of the second layer.
Innovation Solution
Increasing the thickness of the radially inner region of the outer peripheral edge portion of the first layer and introducing a toroidal thickness varying region in the central portion of the first layer, which allows for a step at the boundary between the central and outer peripheral edge portions, enabling sufficient resistance against molding pressure and smooth resin flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the second layer is press-molded using conventional uniform thickness design, then the molding process is simple, but the radially inner region of the outer peripheral edge portion of the first layer is damaged
Solution Approach 1:
The first layer is designed with non-uniform thickness, where the radially inner region of the outer peripheral edge portion has a greater thickness than other regions. This local thickening provides enhanced resistance and protection against damage during press-molding of the second layer, while maintaining uniform thickness in other areas to preserve manufacturing simplicity.
2Device complexity
If the second layer is press-molded with conventional uniform thickness design, then the structure is simple, but the synthetic resin material fails to flow smoothly
Solution Approach 1:
The first layer incorporates a thickness varying region with gradually changing thickness that serves as a flow guide for the synthetic resin material during press-molding. This local variation in thickness directs the resin flow smoothly into the molding cavity, ensuring complete shaping of the second layer without requiring complex overall structure.
3Strength
If the thickness of the radially inner region of the outer peripheral edge portion is increased, then damage resistance is improved, but material consumption increases
Solution Approach 1:
Instead of increasing the thickness of the entire first layer, the invention locally thickens only the radially inner region of the outer peripheral edge portion. This targeted approach provides the necessary damage resistance at the critical area while minimizing overall material consumption.
Solution Approach 2:
The thickness of the radially inner region is increased only to the extent necessary to provide sufficient resistance during press-molding, rather than uniformly thickening the entire first layer. This partial action achieves the required strength while controlling material usage.
Data Source
Figure 1~2
Figure 3~4
AI summary
A container lid comprising a body made of a thin metal plate, the body having a top panel wall, and a skirt wall extending downwardly from the peripheral edge of the top panel wall; and a synthetic resin liner disposed on the inner surface of the top panel wall of the body, the liner being composed of a first layer (26) formed on the inner surface of the top panel wall; and a second layer (28) formed on the lower surface of the first layer. The thickness of a radially inner region of an outer peripheral edge portion (32) of the first layer is rendered larger than the thickness of a radially outer region of a central portion (30) of the first layer to make a step present at the boundary between the central portion and the outer peripheral edge portion. A toroidal thickness varying region (34) whose thickness gradually decreases radially outwardly is made present in the central portion of the first layer.