Bi-stable Plastic Closure Cap with Multi-Component Expansion
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Solution Overview
Problem
Conventional metal can closure caps are limited by being made only of metal, are not cost-effective, lack flexibility for concave end wall designs, and fail to provide airtight and watertight seals, restricting their usability beyond pill boxes.
Innovation Solution
A plastic closure cap design with a softer material expansion section that allows elastic expansion while maintaining a constant angle transition between the end wall and edge section, achieved through multi-component injection molding with varying material stiffness, and a locking ring for sealing engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional metal closure caps are used, then material stiffness and structural integrity are achieved, but cost-effectiveness and weight are worsened
Solution Approach 1:
The patent changes the material parameters by using plastic instead of metal, and further optimizes by creating regions with different material densities through multi-component injection molding. The softer material component provides flexibility where needed while the harder material component maintains structural integrity, achieving the required stiffness with reduced weight compared to solid metal construction.
Solution Approach 2:
The closure cap is constructed as a composite structure with two different material components: a softer material for the expansion section and a harder material for the base structure. This composite approach allows the plastic cap to achieve the structural stiffness previously only available in metal while maintaining the weight and cost advantages of plastic materials.
2Strength
If traditional metal processing with bending hardening is used, then material rigidity at the transition is achieved, but adaptability to plastic materials and concave end wall designs is worsened
Solution Approach 1:
Instead of relying on bending hardening, the patent changes the material parameter by using a softer material component specifically in the expansion section. This softer material allows the transition region to maintain constant angles during bistable deformation while enabling the end wall to be formed with concave curvature, which would be difficult or impossible with traditional metal processing methods.
Solution Approach 2:
The patent applies local quality by using different material properties in different regions of the closure cap. The softer material is specifically placed in the expansion section where flexibility is needed, while the harder material provides structural support in other areas. This local differentiation enables both concave end wall designs and reliable bistable deformation.
3Stability of the object's composition
If the edge section is made uniformly stiff, then structural stability is achieved, but elastic expansion capability is worsened
Solution Approach 1:
The edge section is designed with local quality by using a softer material component specifically in the expansion sections while maintaining harder material in other areas. This allows the expansion sections to elastically deform and increase the outer circumference during bistable deformation, while the rest of the structure maintains its stability and geometric integrity.
Solution Approach 2:
The edge section is segmented into different functional zones: expansion sections made of softer material that provide elastic deformation capability, and intermediate sections with harder material that maintain structural stability. This segmentation allows the closure cap to achieve both expansion flexibility and overall structural stability simultaneously.
4Ease of manufacture
If conventional metal closure caps are used, then manufacturing simplicity is achieved, but sealing capability and airtightness are worsened
Solution Approach 1:
The patent changes the material parameter by using elastomeric or rubber-like material for the locking ring and expansion sections. This material property change enables the creation of effective seals at the interface between the closure cap and the container opening, providing airtight and watertight sealing capability that is not achievable with conventional metal closure caps while still maintaining relatively simple injection molding manufacturing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the production of cost-effective, lightweight, airtight, and watertight closure systems with a concave end wall design, preventing unintentional opening and expanding usability beyond traditional applications.
Implementation Method 1
The expansion section expands elastically under tension and allows the edge region to expand in the state of concave end wall curvature
Data Source
Figure 1a~1g
Figure 2a~2c
Figure 3a~3f
AI summary
The present invention relates to a cover (10, 20, 30) with a bi-stable flap mechanism made of a plastic with at least two material components. The cover (10, 20, 30) can be produced in one piece in a multi-component injection moulding technique. At the transition area between the front wall (11, 21, 31) and the edge portion (12, 22, 32), the plastic is sufficiently stiff (preferably on account of greater material thickness) to ensure that an angle p enclosed in the transition area from the side wall (11, 21, 31) to the edge portion (12, 22, 32) remains constant in both bi-stable states. Expansion portions (14, 24, 34) provided in the edge portion (12, 22, 32) ensure that the outer circumference of the edge portion (12, 22, 32) can increase/decrease from one bi-stable state to the other bi-stable state.