Expandable Rivet Shell Structure for Thinner Can Ends
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Solution Overview
Problem
The challenge in the can manufacturing industry is to reduce the material thickness of can ends while maintaining strength, as thinner materials lead to rivet failure and stress during the forming process, and existing tooling cannot form 'expandable bubbles' that would allow for a stronger rivet with less material.
Innovation Solution
A shell with an expandable bubble is formed into an expandable rivet button and then into an expanded rivet, allowing for the use of sheet material with a base thickness less than 0.0082 inches, using a press with optimized bubble station dimensions to enhance the rivet's overlap and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the base thickness of sheet material is reduced to decrease material usage, then material efficiency is improved, but rivet strength and structural integrity deteriorate
Solution Approach 1:
The patent changes the geometric parameters of the bubble structure (height, diameter, wall thickness distribution) to create an expandable bubble that can form a stronger rivet from thinner material. The bubble station dimensions are optimized to produce a bubble with specific parameters that enable enhanced rivet formation while using less base material.
Solution Approach 2:
The patent introduces a dynamic element - the expandable bubble that can change volume and shape during the forming process. This dynamic structure allows the material to be redistributed and reconfigured to create a stronger rivet structure from thinner gauge material, transforming a static thin-walled structure into a dynamic form that achieves superior mechanical properties.
2Loss of substance
If the base thickness of sheet material is reduced to decrease material usage, then material efficiency is improved, but reliability during forming operations deteriorates
Solution Approach 1:
The patent performs preliminary action by creating the expandable bubble structure before the final rivet forming operation. This pre-formed bubble serves as a prepared substrate that guides the subsequent rivet formation process, ensuring that the rivet develops proper structure and integrity even when formed from thinner material that would otherwise be prone to failure.
Solution Approach 2:
The patent optimizes specific parameters of the bubble structure (wall thickness distribution, curvature radius, height-to-diameter ratio) to enhance reliability during forming. These parameter changes create a bubble geometry that distributes stresses favorably during rivet formation, preventing material failure even with reduced base thickness.
3Loss of substance
If conventional tooling is used with reduced material thickness, then material efficiency is improved, but manufacturing precision deteriorates due to inability to form expandable bubbles
Solution Approach 1:
The patent segments the tooling system into specialized components: an optimized bubble station with specific upper and lower punch geometries, separate from the conventional rivet forming tools. This segmentation allows independent optimization of the bubble formation process to achieve precise control over bubble geometry, which is critical for subsequent rivet formation from thin material.
Solution Approach 2:
The patent changes the dimensional parameters of the bubble station tooling (punch diameters, stroke lengths, positioning accuracy) to enable precise formation of the expandable bubble. These parameter changes in the manufacturing process ensure that the bubble achieves the required geometric precision necessary for reliable rivet formation from reduced-thickness material.
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 solution enables the formation of can ends from thinner sheet material, reducing material usage while ensuring the rivet's strength and integrity, allowing for the use of materials with base thicknesses as low as 0.0078 inches without compromising the can end's performance.
Implementation Method 1
forming the sheet material into a shell, forming an expandable bubble on the shell
Data Source
AI summary
A can end including a central panel with an expandable bubble disposed thereon is provided. The use of an expandable bubble allows for an expandable rivet button and thereafter an expandable rivet that has an enhanced overlap of a tab body. Such an expandable rivet allows for the use of a metal sheet with a thinner base thickness.