Can Lid Score Line Structure to Prevent Opening Derailment
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Solution Overview
Problem
Existing can lids are prone to derailment during opening, particularly under positive internal pressure, leading to lid opening failures due to uneven metal hardness and lever action on auxiliary score lines.
Innovation Solution
A can lid design featuring a score line with a raised portion at its bottom, forming a valley between the inner and outer surfaces, guides the breaking process and prevents derailment by enhancing structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a score line is formed in the panel portion to enable opening by tab operation, then the lid can be opened by breaking the score line, but derailment occurs during breaking causing lid opening failure
Solution Approach 1:
The patent applies local quality by forming a groove at a specific location along the score line to create a localized structural feature. This groove is positioned at a point where derailment is most likely to occur during breaking, and its depth and shape are specifically designed to provide local reinforcement that guides the breaking process and prevents derailment without affecting other areas of the score line.
Solution Approach 2:
The groove is formed in advance during the lid manufacturing process, before the actual opening operation. This preliminary structural preparation ensures that when the tab is pulled and the score line breaks, the breaking process is guided by the pre-formed groove, preventing derailment from the outset rather than attempting to correct it during operation.
2Ease of manufacture
If the panel portion has lower metal hardness outside the coining process portion, then the material is easier to form, but derailment is more likely to occur near the boundary with the coining process portion
Solution Approach 1:
The groove is strategically positioned near the boundary between the coining process portion and the lower hardness region. This local structural feature compensates for the hardness difference by providing a physical guide that ensures the breaking process follows the intended path even when stress concentrates at the boundary due to the material property transition.
3Stability of the object's composition
If positive internal pressure is applied to the can container, then the can is more stable during transport, but the pressure applied to the breaking portion during initial breaking is large causing derailment
Solution Approach 1:
The groove is pre-formed to anticipate and counteract the effect of internal pressure during breaking. When positive internal pressure exists, it naturally pushes the breaking front toward the groove during the opening process, and the groove's geometry is designed to capture and guide this pressure-assisted breaking, ensuring the score line breaks cleanly along the intended path despite the additional force.
Data Source
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AI summary
The can lid (1) includes a panel portion (21), a score line (41) formed on the panel portion (21), a tab (12) for breaking the score line (41), and a raised portion (41d) formed on a bottom portion of at least a part of the score line (41) and forming a valley portion between an inner surface of the score line (41) and the raised portion.