Metal End Closure Threading for Resealable Container Sealing
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Solution Overview
Problem
Existing methods for sealing metallic containers, such as seamed-on end closures and threaded closures, are inconvenient for opening and reclosing, often requiring tools and resulting in sharp edges or increased material costs and damage risks.
Innovation Solution
A method and apparatus that form a thread on both the metallic container and end closure using a joining tool, allowing for a twist-off closure that can be selectively removed and resealed without tools, using a thinner material and reducing the need for additional container thickness or complex capping apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seamed-on end closure is used to seal the metallic container, then the container provides an impermeable barrier and long shelf-life, but the container requires a tool to open and cannot be reclosed
Solution Approach 1:
The end closure is segmented into a body portion and a peripheral flange that can be separated. The peripheral flange is scored to allow it to be pulled away from the container, exposing the threaded body portion for manual opening while maintaining the sealed connection between the threaded portion and container
Solution Approach 2:
The closure transitions from a static seamed-on design to a dynamic system where the peripheral flange can be selectively separated from the container. The scored flange allows controlled separation while the threaded body remains engaged, enabling the closure to adapt between sealed and open states
2Ease of operation
If scores are added to the end closure to form a tear panel, then the container can be opened without a tool, but sharp metal edges are created that may cut the consumer
Solution Approach 1:
The peripheral flange is segmented from the main body through scoring, creating a separate tear-away portion. This segmentation allows the sharp scored edges to be isolated on the detached flange while the smooth threaded body remains engaged with the container, eliminating the cutting hazard
Solution Approach 2:
The harmful scored edges are extracted from the functional sealing portion of the closure. The scores are placed only on the peripheral flange that is intended to be removed, separating the opening function from the sealing function and eliminating the source of sharp edges from the user-contact area
3Strength
If the end closure is made of thicker material to prevent rupture of scores, then the closure is more durable, but the manufacturing cost increases
Solution Approach 1:
The closure has non-uniform thickness distribution. The peripheral flange is made thinner since it is designed to be discarded after opening. The main body and threaded portions maintain sufficient thickness for strength and sealing. This local quality differentiation reduces overall material usage while maintaining durability where needed
4Ease of operation
If threads are formed on the metallic container using a thread roller, then the container can be sealed with a threaded closure, but the container requires additional thickness and the capping apparatus is complex and prone to damage
Solution Approach 1:
Instead of forming threads on the container and using a complex thread roller apparatus, the invention inverts the approach by providing pre-formed threads on the end closure itself. The closure is manufactured with integrated threads during forming, eliminating the need for complex threading equipment and reducing apparatus complexity
Solution Approach 2:
The end closure is self-contained with all threading features pre-formed on the closure body rather than requiring the container to be pre-threaded by external equipment. The closure serves its own threading function, eliminating the need for complex capping apparatus and reducing the number of processing steps
Data Source
AI summary
An apparatus includes a tool operable to releasably join a metallic end closure to a metallic container. In one embodiment, the tool is configured to form a thread in the closure and the container. The tool may optionally crimp the closure to the container. Once sealed, the container can be opened by rotating the closure in an opening direction. The closure can subsequently re-close the container by rotating the closure in a closing direction.