Variable-Thickness Metal Container Necking With Textured Dies
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Solution Overview
Problem
Existing metal container manufacturing processes struggle to efficiently neck containers with varying sidewall thicknesses without causing collapse, buckling, or other physical defects, and require high necking forces, especially when using smooth, polished dies.
Innovation Solution
The use of a necking system with partially textured necking surfaces and relief features in the dies, which reduces surface contact and frictional resistance, allowing for aggressive diameter reduction and successful necking through thick and thin wall portions in a single stroke without defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If smooth, polished dies are used for necking, then the aesthetic finish of container surfaces is improved, but the necking force required increases and physical defects like collapse and buckling occur
Solution Approach 1:
The die surface is given different properties in different zones: the contact area has a textured finish to reduce friction during necking, while other areas maintain smoothness for aesthetic purposes. This local differentiation allows the die to perform both functions effectively.
Solution Approach 2:
Instead of using a smooth surface to reduce friction (conventional approach), the invention uses a textured surface which unexpectedly reduces friction and necking force requirements while preventing defects.
2Productivity
If aggressive diameter reduction is attempted in a single stroke, then productivity is improved, but physical defects like collapse and buckling occur
Solution Approach 1:
The surface texture parameter of the die is changed to reduce friction, enabling larger diameter reductions in a single stroke without causing structural defects. This parameter change allows the material to deform more easily while maintaining integrity.
3Shape
If high necking forces are applied, then aggressive diameter reduction is achieved, but physical defects like collapse and buckling occur
Solution Approach 1:
The die surface is textured in the contact zone to locally reduce friction, allowing aggressive shape change without requiring high forces that would cause structural defects.
Solution Approach 2:
The textured surface, which might seem to increase roughness, actually reduces friction and necking forces, converting a potential disadvantage into a beneficial effect for preventing defects.
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 approach reduces the necking force required, enables greater diameter reduction percentages, and prevents physical defects like collapse and buckling, while maintaining the aesthetic finish of the container surfaces.
Implementation Method 1
reduces surface contact and frictional resistance
Implementation Method 2
reduces a diameter of the section of the sidewall
Implementation Method 3
reduces a diameter of the section of the sidewall by at least 2% in a single stroke
Data Source
Figure 1
Figure 2
Figure 2(a)
AI summary
A shaped metal container comprising less metal than prior art shaped metal containers while still able to handle sufficient axial load and undergo shaping processes, including necking, without wrinkling, buckling, collapsing or other physical defect is disclosed. Processes for shaping a metal container having a sidewall of variable thickness, wherein a portion of the sidewall having a variable thickness is shaped using a die or dies are also disclosed.