Aluminum Blind Rivet Nut for Corrosion-Resistant Mixed Material Joints
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Solution Overview
Problem
Blind rivet nuts made of steel react corrosively with aluminum components, particularly those from the 7000 grade aluminum alloys, and existing solutions either require additional coatings or complex positioning methods to ensure secure connections in mixed material constructions.
Innovation Solution
A component arrangement using a blind rivet nut composed of an aluminum alloy with a bead-like protuberance in the thread-free length section, optimized for precise deformation and secure coupling, allowing for use with steel screw means without additional surface treatments, and incorporating tolerance compensation features to prevent the rivet nut from being pulled out during tightening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If steel blind rivet nuts are used to connect aluminum components, then high tightening forces and low costs are achieved, but intense corrosion occurs between the steel rivet nut and aluminum component
Solution Approach 1:
The blind rivet nut is made from the same aluminum alloy material as the component being connected, eliminating the galvanic corrosion issue between dissimilar metals. This homogeneity of material composition resolves the corrosion problem while maintaining the structural integrity needed for high tightening forces.
Solution Approach 2:
The blind rivet nut utilizes composite structure with an aluminum alloy body that combines the benefits of lightweight material with optimized mechanical properties. The specific aluminum alloy composition provides both the necessary strength for high tightening forces and compatibility with aluminum components to prevent corrosion.
2Object-affected harmful factors
If aluminum alloy blind rivet nuts are used to avoid corrosion, then corrosion resistance is improved, but connection strength decreases requiring special surface treatment
Solution Approach 1:
The invention optimizes the aluminum alloy composition parameters to achieve a balance between corrosion resistance and connection strength. By adjusting the alloying elements and their concentrations, the material properties are tuned to provide both adequate strength for steel screw connections and inherent corrosion resistance without requiring additional surface treatments.
3Strength
If the blind rivet nut is designed with optimized deformation behavior, then secure connection is achieved, but the rivet nut may be pulled out during tightening
Solution Approach 1:
The blind rivet nut incorporates a pre-formed bead-like protuberance in the thread-free length section before installation. This preliminary structural feature is designed to engage with the component during tightening, providing immediate resistance against being pulled out while ensuring secure connection. The pre-existing deformation geometry prevents pull-out failure during the tightening 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
The solution provides a corrosion-resistant, secure connection between aluminum and steel components, enhancing the load-bearing capacity and preventing the rivet nut from being torn out, while allowing for precise positioning and tolerance compensation in mixed material constructions.
Implementation Method 1
The engagement of the screw into the blind rivet causes the latter to deform in a thread-free length section such that a bead-like protuberance is formed
Implementation Method 2
a blind rivet nut composed of an aluminum alloy... wherein the first component is composed of an aluminum alloy... and wherein a screw means for the coupling is composed of a material which has a contact-corrosive action on the first component
Data Source
AI summary
A component arrangement comprising a first component, a second component, at least one screw means and at least one blind rivet nut for insertion into a wall of the first component and for coupling to at least one second component is provided. The blind rivet nut has a rivet head, and the sum of a diameter of the rivet head and twice a spacing between the second component and rivet head corresponds to 0.7 to 1.2 times a diameter of a bead-like protuberance of the blind rivet nut, the second component, in the coupling region, being in contact with the first component only in sections, the second component having a spacing from a rivet head of the blind rivet nut within a plane which is parallel to a contact surface between rivet head and first component. The spacing is greater than a wall thickness of the first component.