Metal Container Curl Flattening for Airtight Valve Sealing
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Solution Overview
Problem
Existing manufacturing processes for metal containers, such as beverage cans and aerosol sprays, face challenges in ensuring a secure airtight closure due to the rounded curled portion of the open end, which lacks sufficient contact with the valve gasket, and previous attempts to create a flat surface through machining weaken the thin metal structure.
Innovation Solution
A two-step process involving pressing the curled portion to achieve a flat surface normal to the container's axis, followed by machining to remove the coating and expose the metal, maintaining the thickness and enhancing the surface for better gasket adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the curled portion is machined to obtain a flat surface, then the contact with the valve gasket is improved, but the thin metal structure is weakened
Solution Approach 1:
The patent applies preliminary action by first pressing the curled portion to create a flat surface before machining. This preliminary pressing action prepares the surface geometry in advance, allowing subsequent machining to remove only the coating layer rather than cutting into the metal substrate, thereby maintaining structural strength while achieving the necessary flat surface for sealing contact.
Solution Approach 2:
The patent segments the flat surface creation process into two distinct operations: (1) pressing to create the flat geometric shape, and (2) machining to remove only the coating layer. This segmentation allows each operation to be optimized independently - pressing shapes the metal without removing material, while machining only removes the thin coating layer, thus avoiding weakening the metal structure.
2Area of stationary object
If the curled portion is pressed to obtain a flat surface, then the contact area with the valve gasket is increased, but the coating on the surface remains
Solution Approach 1:
The pressing operation serves as a preliminary action that creates the flat surface geometry and increases contact area in advance. This prepares the surface for the subsequent machining operation that will remove the coating. The preliminary shaping by pressing allows the final machining step to focus solely on coating removal rather than both shaping and coating removal, improving sealing performance without compromising the metal structure.
3Strength
If the curled portion is left rounded, then the metal structure remains intact, but the contact with the valve gasket is insufficient
Solution Approach 1:
The pressing operation is applied as a preliminary action that modifies the geometry of the curled portion to create a flat surface while preserving the metal structure. By performing this geometric modification before machining, the subsequent machining step only needs to remove the thin coating layer, thereby maintaining structural integrity while enabling sufficient contact area for reliable closure.
Solution Approach 2:
The patent applies local quality by differentiating the treatment of different layers of the curled portion. The pressing operation affects the metal substrate to create flat geometry, while the subsequent machining operation locally removes only the coating layer from the surface. This localized differential treatment ensures the metal structure remains intact while the surface coating is removed to expose clean metal for gasket contact.
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 ensures a robust and secure airtight closure by providing a rougher, exposed metal surface for the gasket, minimizing the risk of weakening the curled portion and improving sealing integrity.
Implementation Method 1
a first sub-step wherein the curled portion is pressed to obtain a flat surface in a plane normal to the main axis of the cylindrical body of the metal container
Implementation Method 2
a second sub-step wherein the pressed curled portion is machined to remove the coating, leaving the metal exposed
Data Source
AI summary
Process and installation for manufacturing metal containers and the metal container obtained with the process. The process includes supplying a metal disc, extruding the disc to form a metal container, applying a coating on the inside of the container, deforming the open end of the container to obtain a neck with a curled portion. The curled portion is pressed to obtain a flat surface in a plane normal to the main axis of the container. The process further includes machining the curled portion that has been previously pressed to remove the coating from the curled portion, leaving the metal of the container exposed.