Can Lid Tab Profile to Prevent Finger Hook Protrusion
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Solution Overview
Problem
In cans with positive internal pressure, the central portion of the can lid expands into a dome shape, causing the finger hook portion of the tab to protrude above the seamed portion, which can lead to issues during conveyance and handling.
Innovation Solution
The can lid tab is designed with an inclined upper surface and/or recessed surfaces on the finger hook portion to prevent it from protruding above the seamed portion, ensuring it remains below the edge even when the lid expands due to internal pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional tab design is used in a positive pressure can, then the tab structure is simple and easy to manufacture, but the finger hook portion protrudes above the seamed portion causing conveyance issues
Solution Approach 1:
The tab is designed with different surface characteristics in different regions: an inclined upper surface on the finger hook portion and a recessed surface on the side portion, while the attachment portion remains flat. This local differentiation allows the finger hook to maintain proper profile under positive pressure without complicating the entire tab structure.
Solution Approach 2:
The tab profile parameters are specifically optimized to prevent protrusion: the inclined upper surface has a controlled angle (5-15 degrees), the recessed surface has a specific depth (0.5-2.0mm), and the finger hook portion dimensions are carefully selected. These parameter changes ensure the tab remains below the seamed portion under positive pressure while maintaining manufacturability.
2Reliability
If the can lid expands due to positive internal pressure, then the can maintains structural integrity, but the finger hook portion protrudes above the seamed portion
Solution Approach 1:
The inclined upper surface and recessed surface are designed in advance to counteract the upward displacement caused by positive pressure. The recessed surface specifically pre-compensates for the expansion by creating a downward offset, ensuring the finger hook portion remains below the seamed portion even when the can lid expands under internal pressure.
Solution Approach 2:
The solution addresses the tab position problem by introducing vertical dimension control through the recessed surface, in addition to the inclined upper surface. This multi-dimensional approach (combining angular inclination with vertical recess depth) provides precise control over the finger hook portion's final position relative to the seamed portion under pressure.
Data Source
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AI summary
A can lid tab (12) includes a flat plate-shaped attachment portion (51) including a rivet hole (51a) to be attached to a rivet portion (32) provided in a panel portion (21) of a can lid (1), the attachment portion being in contact with the panel portion (21); a tip portion (52) continuous with the attachment portion (51); and a finger hook portion (53) formed on a side opposite to the tip portion (52) across the attachment portion (51), at least an upper surface on a rear end side of the finger hook portion being inclined downward from the tip portion (52) side toward the rear end side with respect to the attachment portion (53).