Selective Can End Shell Thinning Without Forming Wrinkles
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Solution Overview
Problem
The can making industry faces challenges in reducing the amount of metal used in can ends while maintaining strength, as thinner gauges tend to wrinkle during formation, and previous methods to reduce metal volume compromise the space for scorelines and pull tabs.
Innovation Solution
A selectively formed shell is created by stretching and thinning specific areas of the material, maintaining base metal thickness in critical areas like the center panel and outer lip to prevent wrinkling, while reducing material in other areas like the chuck wall, using precise tooling geometry and interaction to achieve weight reduction without compromising strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thinner gauge material is used to reduce metal consumption, then material usage decreases, but the can end tends to wrinkle during forming
Solution Approach 1:
The patent applies different material thicknesses to different regions of the can end. The lip region uses thinner material (0.006-0.010 inches) to reduce overall metal consumption, while the center panel and field region maintain base gauge thickness (0.012-0.020 inches) to prevent wrinkling during forming and ensure structural integrity. This localized differentiation resolves the contradiction between material reduction and forming quality.
Solution Approach 2:
The can end is segmented into distinct regions with different thickness characteristics: a thinned lip region, a base gauge center panel, and an intermediate transition zone. This segmentation allows each region to be optimized independently - the lip for weight reduction and the center panel for forming stability - thereby resolving the contradiction between material usage and manufacturing precision.
2Quantity of substance
If blank size is reduced to reduce metal volume, then material consumption decreases, but the area for scoreline, severable panel and pull tab is compromised
Solution Approach 1:
The patent concentrates material thinning specifically in the lip region while preserving base gauge thickness in the center panel where the scoreline, severable panel, and pull tab are located. This localized approach reduces overall metal volume while maintaining adequate end panel area for functional components, resolving the contradiction between material reduction and functional area preservation.
3Weight of stationary object
If selective stretching and thinning is applied to reduce material, then weight reduction is achieved, but additional forming complexity is introduced
Solution Approach 1:
The patent incorporates the thinning action into the initial shell forming operation itself, rather than requiring separate subsequent operations. The draw die geometry is specifically designed to stretch and thin the lip region during the primary forming stroke, achieving weight reduction without adding significant complexity to the forming process or requiring additional tooling stations.
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 overall material and weight of can ends while maintaining strength, preventing issues like wrinkling and ensuring adequate space for scorelines and pull tabs, achieving significant cost savings without increasing initial material processing costs.
Implementation Method 1
the blank is stretched and thinned in selected areas to reduce the amount of metal required while maintaining the desired strength
Data Source
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AI summary
A shell, a container employing the shell, and tooling and associated methods for forming the shell are provided. The shell includes a center panel, a circumferential chuck wall, an annular countersink between the center panel and the circumferential chuck wall, and a curl extending radially outwardly from the chuck wall. The material of at least one predetermined portion of the shell is selectively stretched relative to at least one other portion of the shell, thereby providing a corresponding thinned portion.