Reverse Bubble Rivet Button for Thinner Can End Metal
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Solution Overview
Problem
Existing rivet forming methods and tooling face challenges in maintaining strength and consistency while reducing the thickness of metal used in can ends, leading to issues such as tearing and uneven staking, particularly with thinner gauge materials.
Innovation Solution
A press and method that forms a reverse bubble on a shell, creating a concave central portion and convex sidewall, which is then formed into a rivet button and staked to secure a pull tab, allowing for the use of thinner materials with enhanced rivet properties and reduced metal consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If thinner gauge metal is used in can ends, then metal consumption is reduced, but rivet strength and consistency deteriorate causing tearing and uneven staking
Solution Approach 1:
The reverse bubble is formed in advance during the shell forming process, creating a pre-shaped construct with concentrated material in the central portion. This preliminary action prepares the material distribution before rivet forming, enabling thinner gauge metal to achieve adequate rivet strength by having the material already positioned and concentrated where needed for the rivet button formation.
Solution Approach 2:
The reverse bubble creates a localized concentration of material in the central portion of the shell where the rivet will be formed. This local quality change ensures that the thickest material is precisely where the rivet button needs to be, providing localized strength enhancement without requiring increased thickness throughout the entire can end, thus reducing overall metal consumption while maintaining rivet integrity.
2Ease of manufacture
If traditional bubble formation is used, then rivet forming is simplified, but material distribution becomes uneven leading to tearing and inconsistent staking
Solution Approach 1:
Instead of forming a traditional convex bubble that pushes material outward and creates thinning at the center, this invention inverts the approach by forming a reverse bubble with a concave central portion. This inversion causes material to flow inward and concentrate at the center during forming, achieving uniform material distribution and consistent thickness in the rivet button area, which eliminates tearing and ensures consistent staking while maintaining ease of manufacture.
3Productivity
If conventional rivet forming is used with thinner materials, then productivity is maintained, but product reliability decreases due to tearing and uneven staking
Solution Approach 1:
The reverse bubble construct is formed in advance during shell formation, pre-positioning the material concentration needed for reliable rivet formation. This preliminary action ensures that when thinner gauge metal is used, the material is already optimally distributed for rivet button creation, preventing tearing and ensuring consistent staking without requiring slower production speeds or additional corrective operations, thus maintaining productivity while improving reliability.
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
The reverse bubble formation enhances rivet strength and consistency, enabling the use of thinner materials with improved tear resistance and reduced metal consumption without compromising the integrity of the can end.
Implementation Method 1
The upper tooling assembly and the lower tooling assembly are structured to form a reverse bubble when the upper tooling assembly is in the second position
Data Source
AI summary
A rivet forming method includes providing a sheet material with a base thickness, forming the sheet material into a shell, forming a reverse bubble on the shell, forming the shell into a can end, forming the reverse bubble into a rivet button, staking the rivet button to secure a pull tab to the can end, and performing finishing operations on the can end. The reverse bubble provides enhanced rivet forming processes and properties and allows for the use of a metal sheet with a thinner base thickness.