Aluminum Container Sheet Heat Treatment for Better Necking Formability
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Solution Overview
Problem
The container industry faces challenges in producing metal beverage containers with expanded diameters or necked shapes, as existing methods often require multiple operations and result in failures such as curl splits, container fracture, and surface defects like striations and ridges, which lead to high reject rates during forming processes.
Innovation Solution
A method involving heating aluminum alloy ingots to a specific temperature to achieve a dispersoid f/r value of less than 7.65 before rolling them into sheets, which are then formed into containers with reduced surface striations and ridges, using 3xxx or 5xxx series alloys with controlled Mn and Mg content, and specific thickness ranges to minimize forming failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If multiple expansion dies and forming operations are used to expand container diameter or create necked shapes, then container shape complexity is improved, but container failure rate increases due to curl splits, fractures, and surface defects
Solution Approach 1:
The invention changes the material parameters of the aluminum alloy by controlling the dispersoid phase characteristics (size, distribution, and volume fraction) through specific alloying compositions and heat treatment parameters. This modifies the mechanical properties and formability of the material, allowing complex shaping operations to be performed with reduced risk of failure.
Solution Approach 2:
The invention performs preliminary heat treatment of the aluminum alloy sheet before forming operations to optimize the dispersoid phase structure. This pre-treatment prepares the material in advance to better withstand subsequent necking, curling, and threading operations, reducing the likelihood of defects during these processes.
2Productivity
If conventional aluminum alloy sheets are used in forming operations, then production efficiency is maintained, but surface quality deteriorates due to striations and ridges
Solution Approach 1:
The invention modifies the microstructural parameters of the aluminum alloy by controlling dispersoid phase characteristics through specific alloy compositions (Mn: 0.2-1.0 wt%, Mg: 0.1-1.0 wt%) and heat treatment parameters. This results in reduced surface striations and ridges during forming while maintaining production efficiency.
3Reliability
If aluminum alloy composition and heat treatment are optimized to reduce dispersoid f/r below 7.65, then formability and surface quality are improved, but processing complexity increases
Solution Approach 1:
The invention establishes specific parameter ranges for alloy composition (Mn: 0.2-1.0 wt%, Mg: 0.1-1.0 wt%) and heat treatment (temperature and time to achieve dispersoid f/r < 7.65) that optimize formability. These defined parameters provide a clear processing protocol that, while requiring precision, systematic1ize the complex heat treatment process.
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 enhances the formability of aluminum alloy sheets, reducing container failures and reject rates during downstream forming operations like necking, curling, and threading, resulting in smoother surfaces and improved container quality.
Implementation Method 1
heating aluminum alloy ingots to a specific temperature to achieve a dispersoid f/r value of less than 7.65 before rolling them into sheets
Data Source
AI summary
In some embodiments of the present invention a method includes: obtaining a first aluminum alloy sheet formed from rolling a first ingot of a 3xxx or a 5xxx series aluminum alloy, wherein, prior to rolling, the first ingot has been heated to a sufficient temperature for a sufficient time to achieve a first dispersoid f/r of less than 7.65; and forming a container precursor from the first aluminum alloy sheet, wherein when the first aluminum alloy sheet is formed into the container precursor, the container precursor has less observed surface striations and ridges as compared to a container precursor formed from a second aluminum alloy sheet rolled from a second ingot having a second dispersoid f/r value of 7.65 or greater.