Pipe-to-Flange Press-Fit Joint for Dissimilar Metal Strength
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Solution Overview
Problem
The joining of dissimilar metals like steel and aluminum in multi-materialization is challenging due to differences in properties, leading to issues with joining strength, formability, forming load, and dimensional accuracy, and existing methods do not adequately address material-specific considerations for improved joining strength and durability.
Innovation Solution
A joined body configuration where the spring-back amount of a cylindrical flange portion is greater than the first member, allowing for increased contact area and pressure distribution, enhancing joining strength and durability by selecting materials based on tensile strength and Young's modulus, and using a press-fitting method with a rubber member to expand the flange portion and first member for secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high tension steel is used to reduce weight and improve safety, then strength and safety are improved, but the weight is still heavier than aluminum and formability decreases
Solution Approach 1:
The invention uses a composite structure combining high tension steel (first member) and aluminum alloy (second member) to achieve both high strength and low weight. The steel provides structural strength while the aluminum reduces overall weight, resolving the contradiction between strength requirements and weight reduction goals in vehicle construction.
2Strength
If high tension steel is used, then strength is improved, but forming load increases and dimensional accuracy decreases
Solution Approach 1:
The invention changes the material parameter by using aluminum alloy for the second member instead of continuing with high tension steel throughout. This material substitution reduces the forming load and improves dimensional accuracy during the forming process while maintaining the high strength characteristics of the steel portion.
3Adaptability or versatility
If dissimilar metals are joined together, then multi-materialization is achieved, but joining strength is insufficient
Solution Approach 1:
The invention applies local quality by creating a specific structural configuration where the first member has a hollow cylindrical shape with a flange, and the second member fits into this flange. This localized structural design at the joining interface enhances the joining strength between dissimilar metals through optimized geometric configuration and material distribution.
4Ease of manufacture
If conventional joining methods are used, then joining is achieved, but contact area is small and durability is reduced
Solution Approach 1:
The invention uses a curved surface configuration where the outer circumferential surface of the second member contacts the inner circumferential surface of the flange in a curved contact pattern. This curvature increases the contact area compared to flat or point contact, thereby improving durability and load distribution at the joining interface.
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 improves joining strength and durability by optimizing material selection and contact area, while maintaining high dimensional accuracy and reducing thermal strain compared to welding, thereby addressing the limitations of existing methods for joining dissimilar metals.
Implementation Method 1
an elastic body (urethane rubber member) is inserted inside the pipe body (pipe member), and the elastic body is pressed to be deformed, whereby the pipe body is expanded, and the wall surface body and the pipe body are joined together by press-fitting
Implementation Method 2
since the spring-back amount of the cylindrical flange portion arranged outside the first member is larger than the spring-back amount of the first member, the flange portion tightens the first member, so that the joining strength can be improved
Data Source
Figure 1~2
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AI summary
A joined body 1 includes: a first member 10 having a pipe shape; and a second member 20 including a wall portion 21 having a plate shape, and a flange portion 122 having a cylinder shape provided with an insertion hole 122a through which the first member 10 is inserted. In a state where the first member 10 is inserted into the insertion hole 122a of the flange portion 122 of the second member 20, the first member 10 and the second member 20 are joined with the first member 10 pipe-expanded. A material of the second member 20 is larger than a material of the first member 10 in a spring-back amount.