Selective Shell Thinning for Wrinkle-Resistant Can Ends
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Solution Overview
Problem
The can making industry faces challenges in reducing the amount of metal used while preventing issues like wrinkling and uneven thinning in can ends formed from thin gauge material.
Innovation Solution
The use of tooling with a force and/or pressure concentrating forming surface and a hybrid bias generating assembly allows for selective stretching and thinning of predetermined portions of the shell, reducing material usage while minimizing uneven thinning and tooling overload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the blank size for the can end is reduced to use less material, then material consumption is reduced, but the area of the end panel is sacrificed
Solution Approach 1:
The patent applies local quality by selectively thinning specific portions of the can end shell (such as the chuck wall and flange areas) while maintaining full gauge thickness in critical areas (center panel, countersink, and curl). This allows material reduction in non-critical areas without compromising the structural integrity or functionality of the can end, thereby reducing overall material consumption while preserving adequate end panel area.
2Loss of substance
If thinner gauge material is used to reduce material consumption, then material usage is reduced, but the can end tends to wrinkle during forming
Solution Approach 1:
The patent uses local quality to maintain different material thicknesses in different areas of the shell. Critical areas that are prone to wrinkling during forming (center panel, countersink, and curl) retain the base gauge thickness, providing sufficient structural support and wrinkle resistance. Non-critical areas (chuck wall and flange) are selectively thinned to reduce overall material usage. This differential thickness approach prevents wrinkling in critical areas while achieving material reduction goals.
Solution Approach 2:
The patent applies preliminary action by pre-thinning specific portions of the shell before the final forming operations. The selective thinning is performed in a controlled manner during the forming process, allowing the material to be gradually thinned while maintaining structural integrity. This preliminary thinning of non-critical areas prepares the shell for subsequent forming operations without causing wrinkling, as the critical areas retain sufficient thickness to support the forming loads.
3Loss of substance
If selective stretching is applied to thin predetermined portions of the shell, then material thickness is reduced, but uneven thinning and tooling overload may occur
Solution Approach 1:
The patent applies segmentation by dividing the shell into distinct zones with different thinning requirements: critical areas (center panel, countersink, curl) that maintain base gauge thickness, and non-critical areas (chuck wall, flange) that are selectively thinned. The tooling is designed with multiple forming surfaces that independently control the thinning process in each zone, preventing uneven thinning across the entire shell. This segmented approach allows precise control over material thickness distribution while avoiding tooling overload through distributed forming loads.
Solution Approach 2:
The patent uses parameter changes by varying the forming pressure and contact surface characteristics across different areas of the shell during the forming process. The tooling incorporates surfaces with different radii of curvature and contact areas, creating localized parameter changes that control the degree of thinning in each region. Critical areas experience higher forming pressures and shorter contact times to maintain thickness, while non-critical areas experience lower pressures and longer contact times to achieve controlled thinning. This parameter variation ensures uniform thinning in thinned areas while preventing excessive thinning or tooling overload.
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 enables a significant reduction in material thickness, particularly in the chuck wall, while maintaining base gauge thickness in critical areas, thus reducing material consumption and processing costs without compromising the structural integrity of the can ends.
Implementation Method 1
selectively stretching at least one predetermined portion of the shell relative to at least one other portion of the shell to provide a corresponding thinned portion
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. The tooling includes a pressure concentrating forming surface.