Screw Cap Safety Ring Radial Stress Resistance
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Solution Overview
Problem
Existing screw closure devices for containers are prone to inadvertent breakage of connection links due to radial and axial stresses, occurring during manufacturing, assembly, or transport, which can lead to premature detachment of the safety ring from the capsule.
Innovation Solution
A screw cap with a safety ring featuring teeth and cavities that resist radial movements and spacing elements to limit axial movements, ensuring the integrity of the link elements until the first opening, while allowing intentional opening through a designed shape and angle configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If frangible link elements are made fragile to allow easy opening, then ease of operation is improved, but reliability deteriorates due to inadvertent breaking during handling and assembly
Solution Approach 1:
The link elements are segmented into two functional zones: an upper fragile portion that breaks during intentional opening, and a lower robust portion that resists inadvertent breaking during handling. This segmentation allows the same component to serve both purposes of easy opening and high reliability during transport.
Solution Approach 2:
Different portions of the link elements have different mechanical properties. The upper portion is designed with lower strength to facilitate opening, while the lower portion near the capsule has higher strength to prevent accidental breaking during assembly and handling. This local differentiation of material properties resolves the contradiction between ease of opening and reliability.
2Device complexity
If safety ring is positioned close to capsule for compact design, then device complexity is reduced, but reliability worsens due to increased radial stress on link elements
Solution Approach 1:
The link elements incorporate a localized reinforcement zone in their lower portion that provides enhanced radial strength without increasing the overall distance between the safety ring and capsule. This local strengthening allows compact design while maintaining reliability under radial stress during handling and assembly.
3Reliability
If additional reinforcement structures are added to prevent link breakage, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The protective function is merged into the link elements themselves through integrated geometric features (the robust lower portion) rather than adding separate reinforcement components. This combining of structure and function maintains reliability while avoiding increased device complexity and manufacturing cost.
Solution Approach 2:
The link elements are designed to be self-protecting through their own geometric configuration, where the robust lower portion inherently resists inadvertent breaking without requiring external reinforcement structures. The structure serves its own protective function, eliminating the need for additional components.
Data Source
Figure 1
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AI summary
Herein described is a closure cap for a container (48), of the type comprising a capsule (10) of a substantially cylindrical shape, threaded internally, provided with a side wall (14) on the lower edge (16) of which a plurality of frangible link elements (18) are provided connecting the lower edge (16) of the capsule (10) to the upper edge (20) of a safety ring (12). On the upper edge (20) of the safety ring (12) there is, made in one piece with the safety ring (12), one or more teeth (22) projecting in axial direction upwards towards the side wall (14) of the capsule (10). The upper portion of each tooth (22) is positioned in shape coupling within a corresponding cavity (24) provided on the side wall (14) of the capsule (10) at its lower edge (16). Each cavity (24) is provided with a bottom wall (26) extending in the axial direction of the cap and against which the related tooth (22) abuts preventing the capsule (10) and the safety ring (12) from being subjected to related movements in the radial direction of the cap such to cause damage to one or more of the link elements (18).