Laminated Aluminum-Copper Button Cap Reducing Spring Back
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Solution Overview
Problem
Conventional button caps made of copper or copper alloy tend to experience spring back when swaged, leading to a weakened coupling force and potential rotation over time, which can cause design orientation displacement, and adding reinforcement members increases costs and complexity.
Innovation Solution
A cap composed of an inner layer of aluminum or aluminum alloy and an outer layer of a harder material like copper, nickel, or zinc alloy, laminated continuously across the bottom and circumferential side, reducing spring back and enhancing scratch resistance without increasing the number of parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a cap is made of copper or copper alloy to prevent scratching, then scratch resistance is improved, but spring back occurs during swaging which weakens coupling force and causes rotation
Solution Approach 1:
The cap is divided into two functional layers: an inner layer made of aluminum or aluminum alloy that provides dimensional stability and resists spring back during swaging, and an outer layer made of copper or copper alloy that provides scratch resistance and aesthetic appearance. This segmentation allows each layer to perform its specialized function without compromising the other.
Solution Approach 2:
The invention uses a composite structure combining aluminum or aluminum alloy with copper or copper alloy in a laminated configuration. This composite material approach leverages the advantages of both materials: aluminum's low spring back characteristics and copper's high scratch resistance and visual appeal, creating a cap that satisfies both reliability and aesthetic requirements.
2Reliability
If a reinforcement member is added to prevent cap rotation, then coupling force stability is improved, but the number of parts increases leading to higher cost and manufacturing complexity
Solution Approach 1:
The reinforcement function is merged into the cap structure itself through the aluminum inner layer, eliminating the need for separate reinforcement members. The aluminum layer's inherent low spring back properties provide the necessary dimensional stability and coupling force stability during swaging, while maintaining a simple two-layer construction without additional components.
Solution Approach 2:
The composite structure of aluminum and copper layers integrates the reinforcement function within the cap's own structure. The aluminum inner layer acts as the reinforcement element, providing structural stability and preventing rotation during swaging, while the copper outer layer maintains the aesthetic appearance. This eliminates the need for separate reinforcement members and reduces overall complexity.
3Object-affected harmful factors
If copper or copper alloy is used for the cap, then scratch resistance is improved, but material cost increases compared to aluminum or aluminum alloy
Solution Approach 1:
The cap applies local quality by using copper or copper alloy only on the outer layer where scratch resistance and aesthetic appearance are required, while using aluminum or aluminum alloy for the inner layer where structural stability is needed. This localized material assignment optimizes cost by using expensive material only where necessary for appearance and surface properties.
Solution Approach 2:
The composite structure combines expensive copper or copper alloy with more cost-effective aluminum or aluminum alloy. The aluminum inner layer provides the bulk structural support at lower cost, while the copper outer layer provides the premium surface properties. This composite approach reduces overall material cost compared to using copper throughout, while maintaining the desired scratch resistance and appearance.
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 solution effectively prevents cap rotation and maintains strength, reducing spring back while keeping the cap scratch-resistant and cost-effective by using aluminum for the inner layer and a harder material for the outer layer, thus addressing the issues of spring back and cost in conventional designs.
Implementation Method 1
spring back tends to occur when the circumferential side of the cap is swaged to the main body using a die or the like. In the spring back, the deformed circumferential side is somewhat returned toward its original state when the die or the like is removed.
Implementation Method 2
the second material is copper or copper alloy that is relatively hard to scratch
Data Source
AI summary
There is provided a cap, which is one part of a button fastener. The cap comprises a bottom and a circumferential side rising from an edge of the bottom. The cap is composed of an inner layer made of aluminum or aluminum alloy as a first material and an outer layer made of copper or copper alloy as a second material. The first and second layer are laminated on each other continuously across the bottom and the circumferential side. A Vickers hardness of the second material may be harder than a Vickers hardness of the first material. A tensile strength of the first material may be less than 260 N/mm2, and a tensile strength of the second material may be equal to or higher than 260 N/mm2.