Friction Rivet Joining Dissimilar Materials
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Solution Overview
Problem
Current friction rivet technologies are limited in joining non-steel and steel materials due to the requirement for similar hardness levels between the rivet and the steel material, and the use of adhesives can reduce welding strength and stiffness, especially when joining light-weight materials like aluminum alloys or plastics with steel.
Innovation Solution
A friction rivet design featuring a head part, body part, and cavity with a first insert of low carbon steel and a second insert of thermoplastic resin, where the second insert is melted and discharged through a flow path to enhance joining performance and repair damage, allowing for effective joining regardless of the steel material's hardness and reducing the risk of galvanic corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If friction rivet joining is used to join light-weight materials and steel materials, then weight reduction is achieved, but welding strength is lowered when adhesives are applied
Solution Approach 1:
The friction rivet is divided into multiple functional segments: a head part, a body part, a cavity, and two distinct inserts (first insert for friction welding, second insert for adhesive containment). This segmentation allows each component to perform its specific function optimally, enabling the system to achieve both weight reduction and maintain welding strength despite the presence of adhesives.
Solution Approach 2:
The first insert acts as an intermediary element between the friction rivet body and the steel material. It is specifically designed to generate frictional heat and achieve welding with the steel material, while the second insert serves as an intermediary to contain and manage the adhesive, preventing it from interfering with the friction welding process. This intermediary mechanism resolves the contradiction between using adhesives for reinforcement and maintaining welding strength.
2Strength
If friction rivet is rotated to generate frictional heat for welding, then joining force is improved, but damage to the upper plate increases
Solution Approach 1:
The second insert filled with adhesive acts as a protective intermediary between the rotating friction rivet and the upper plate. As the rivet rotates and generates frictional heat, the adhesive in the second insert melts and flows out through the flow path, forming a protective layer that reduces direct contact and friction between the rivet and the upper plate, thereby minimizing damage while maintaining effective joining force.
Solution Approach 2:
The adhesive in the second insert undergoes a phase transition from solid to liquid due to the frictional heat generated during rotation. This phase change allows the adhesive to flow out through the flow path, reducing mechanical damage to the upper plate while the heat continues to be transmitted for welding the first insert to the lower plate.
3Ease of manufacture
If a single material rivet is used for friction joining, then manufacturing is simplified, but adaptability to different material hardness levels is limited
Solution Approach 1:
The friction rivet is segmented into a body part made of one material and two inserts made of different materials. This segmentation allows the first insert to be selected for optimal friction welding performance with the lower plate material, while the second insert is selected for adhesive containment and upper plate protection. The body part can be made of a standard material, simplifying manufacturing, while the inserts provide the necessary adaptability to different material combinations.
Solution Approach 2:
The friction rivet employs a composite structure combining different materials in specific components. The first insert can be made of a material optimized for friction welding with steel (e.g., a harder metal), while the second insert is made of a material suitable for adhesive containment (e.g., a softer material or polymer). This composite approach maintains manufacturing simplicity for the body while providing versatility in material compatibility through the selectable inserts.
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 enables robust joining of different materials with improved welding strength, flexibility in material compatibility, and reduced risk of galvanic corrosion, enhancing product quality and marketability by using frictional heat to weld and discharge the second insert, thus overcoming the limitations of existing technologies.
Implementation Method 1
a friction area B between the first insert 30 and the lower plate 90 is generated... welding a first insert and the lower plate using frictional heat generated from a friction area
Implementation Method 2
welding a first insert and the lower plate using frictional heat generated from a friction area by continuously rotating and pressurizing the friction rivet
Implementation Method 3
melting a second insert using frictional heat transmitted through the first insert
Implementation Method 4
melting a second insert using frictional heat transmitted through the first insert and thus discharging the second insert in a molten state
Data Source
AI summary
Disclosed are a friction rivet for joining a non-steel material and a steel material and a joining method using the same, wherein inserts are applied to the friction rivet and, thus, the friction rivet doesn't need to be replaced according to materials of a lower plate and damage to an upper plate caused by penetration into the upper plate by the friction rivet may be repaired.