Two-Step Curl Formation for Metal Bottle Sealing
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Solution Overview
Problem
The formation of metal bottles requires multiple necking operations to create a smaller opening, leading to issues like metal hardening, increased costs, and less desirable tolerances due to spring back in the curl formation process.
Innovation Solution
A process involving an internal form plug with a pre-curl groove and an external forming device with a form roller to create a pre-curl in the neck of the container, followed by a cutter to remove the neck, allowing for a two-step curl formation that reduces spring back and improves tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If multiple necking operations are used to decrease the diameter of the opening in the can, then the opening diameter is reduced, but the metal material hardens and spring back increases
Solution Approach 1:
The patent divides the curl formation into two distinct stages: pre-curl formation followed by final curl formation. This segmentation allows the metal to be gradually deformed rather than subjected to multiple aggressive necking operations, reducing work hardening while achieving the desired small opening diameter.
Solution Approach 2:
The pre-curl groove is formed in advance on the internal form plug before the final curling operation. This preliminary action prepares the metal in a controlled manner, creating a pre-curved shape that requires less force during final curl formation, thereby reducing metal hardening and spring back.
2Length of stationary object
If multiple necking operations are used to create a smaller opening, then the opening diameter is reduced, but manufacturing complexity and costs increase
Solution Approach 1:
The patent combines pre-curl formation and final curl formation into a single integrated forming operation. The internal form plug with pre-curl groove and external forming device work together in one continuous process, eliminating the need for separate necking operations and reducing manufacturing complexity.
Solution Approach 2:
The pre-curl groove is pre-formed on the internal form plug, which guides the metal deformation during the single forming operation. This preliminary preparation of the forming tool allows the metal to follow the desired path, achieving the small opening diameter in one operation rather than multiple necking steps.
3Ease of manufacture
If traditional curl formation is used, then the process is simple, but tolerances are loose due to spring back
Solution Approach 1:
The internal form plug with pre-curl groove acts as an intermediary tool that precisely defines the desired curl shape. The metal conforms to this intermediary form during deformation, ensuring accurate tolerances while maintaining process simplicity through the single-forming operation.
Solution Approach 2:
The pre-curl groove is pre-formed on the internal form plug to match the desired final curl shape. This preliminary preparation of the forming surface guides the metal deformation, minimizing spring back and achieving closer tolerances without complicating the manufacturing process.
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
This method simplifies the curl formation process, reduces metal hardening, and achieves closer tolerances in the final curl, enabling more precise and reliable sealing by minimizing spring back and eliminating the need for multiple necking operations.
Implementation Method 1
rotating the closable container and the form roller to form the pre-curl in the neck of the closable container
Implementation Method 2
Necking operations are known to harden the metal material, especially when multiple necking operations are used to decrease the diameter of the opening in the can
Data Source
AI summary
Disclosed is a device and method for forming a curl in a closable container. A process of forming a pre-curl is used, which is followed by a second separate step of forming the completed curl. The two-step process provides for higher tolerances with respect to the shape of the curl that allows the curl to be used as a sealing surface for a recloseable metal bottle. A three-step process provides for even greater tolerances and reduces longitudinal forces by completing the curl using lateral forces.