Pre-Coated Can Wall Ironing for Tapers Without Coating Damage
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Solution Overview
Problem
Current can manufacturing processes using pre-coated metal face challenges such as limited thickness reduction, damage to polymer coatings, burr formation, and difficulty in forming tapers or steps, which affects the production of nestable cans and increases costs.
Innovation Solution
A method involving a two-part tooling apparatus that reduces the thickness and increases the height of a metal cup's cylindrical wall by using an annular wall-ironing die and punch with varying diameters, allowing for controlled wall-ironing and burnishing to prevent coating damage, while enabling the formation of tapers and steps to create nestable cans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional wall-ironing process is used to reduce can wall thickness, then material cost is minimized, but the polymer coating is damaged
Solution Approach 1:
The patent changes the geometric parameters of the wall-ironing tools, specifically providing the punch and die with non-circular cross-sections (such as polygonal or oval shapes) instead of conventional circular sections. This parameter change modifies the ironing action to reduce coating damage while maintaining wall thickness reduction effectiveness
Solution Approach 2:
The patent applies partial wall-ironing by limiting the ironing process to specific zones of the can wall rather than uniformly ironing the entire circumference. The non-circular punch and die configuration enables selective thinning in certain regions while preserving coating integrity in others
2Manufacturing precision
If wall-ironing is used to reduce thickness, then can wall thickness is reduced, but burrs are formed on the can edge
Solution Approach 1:
The patent changes the cross-sectional geometry parameters of the wall-ironing punch and die from circular to non-circular shapes. This parameter modification alters the deformation pattern during ironing, enabling better control over wall thickness reduction while minimizing burr formation at the can edge
3Ease of manufacture
If conventional circular wall-ironing die is used, then can body is formed, but tapers or steps cannot be formed affecting nestability
Solution Approach 1:
The patent changes the cross-sectional shape parameters of the wall-ironing tools from circular to non-circular configurations. This enables the formation of tapers, steps, or other geometric variations in the can body wall that were not achievable with conventional circular tools, thereby improving nestability
Solution Approach 2:
The non-circular punch and die configuration enables different regions of the can wall to have different thicknesses or geometries. This local variation in wall properties allows formation of tapers and steps in specific zones while maintaining uniform walls in other areas, enhancing nestability without compromising overall can integrity
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 effectively reduces the thickness of pre-coated metal cans while preserving the coating, allows for the formation of tapers and steps, and enhances the nestability of cans, thereby reducing production costs and improving manufacturing efficiency.
Implementation Method 1
reducing the thickness and increasing the height of a cylindrical wall of a metal cup
Implementation Method 2
As the metal in the can body passes through each wall-ironing stage it generally becomes more work-hardened
Data Source
AI summary
A method of reducing a thickness and increasing a height of a cylindrical wall of a metal cup to form a can body comprises positioning a wall-ironing punch inside the cup, moving an annular wall-ironing die axially over the closed end of the cup towards the open end of the cup, but not beyond the open end of the cup, in order to iron the cylindrical wall from the closed end up to a position axially spaced from the open end and moving the wall-ironing die back in an opposite direction to remove the can body from the die. Methods of altering a diameter of one or more regions of a can body are also disclosed.