Friction Stir Joining with Tapered Pin and Auxiliary Insert
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Solution Overview
Problem
Conventional joining methods face challenges in easily inserting the stirring pin of a rotary tool into an auxiliary member and in managing the load on the friction stir device, which can lead to tool damage and increased costs.
Innovation Solution
A joining method using a rotary tool with a stirring pin of smaller diameter towards the tip, where the tool is inserted only from the front face side of an auxiliary member softer than the metal members, reducing load on the device and enhancing tool longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a column-shaped stirring pin is used in conventional friction stir welding, then the joining process can be performed, but it is difficult to insert the stirring pin into the auxiliary member
Solution Approach 1:
The stirring pin is inverted from a column shape to a tapered shape with smaller diameter at the tip, allowing easier insertion into the auxiliary member while maintaining functional effectiveness during friction stir welding
Solution Approach 2:
The diameter parameter of the stirring pin is changed along its length, creating a tapered geometry that facilitates insertion into the auxiliary member while preserving the necessary stirring function
2Productivity
If the shoulder portion of the rotary tool is brought into contact with the metal members during friction stirring, then the joining process can be performed, but the load acting on the friction stir device is enlarged
Solution Approach 1:
The shoulder portion contact function is extracted from the joining process. Only the stirring pin contacts the auxiliary member and metal members, removing the additional load that would be imposed by shoulder portion contact on the friction stir device
Solution Approach 2:
The auxiliary member serves as an intermediary between the stirring pin and the metal members, allowing the stirring pin to perform friction stirring without the shoulder portion needing to contact the metal members directly
3Strength
If friction stirring is performed by inserting the rotary tool into the softer auxiliary member, then harder metal members can be joined, but the tool is severely damaged increasing cost
Solution Approach 1:
The contact relationship is inverted so that only the stirring pin contacts the auxiliary member and metal members, not the entire rotary tool including the shoulder portion. This selective contact reduces severe damage to the tool while maintaining the ability to join harder metal members
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 method allows for easier insertion of the rotary tool, reduces the load on the friction stir device, prolongs the life of the tool, and enhances the joining strength by bringing the stirring pin into slight contact with the metal members.
Implementation Method 1
friction stirring is performed by inserting the rotary tool into the auxiliary member
Data Source
AI summary
The present invention includes a joining process in which a first metal member and a second metal member are joined with an auxiliary member interposed therebetween by moving a rotary tool along a butted portion in a state where the rotary tool being rotated is inserted only from a front face side of the auxiliary member, only a stirring pin is in contact with the auxiliary member, a base end side of the stirring pin is exposed, and an outer circumferential face of the stirring pin is slightly in contact with the first metal member and the second metal member, and the auxiliary member is provided with an inclined face on at least one side face in such a form that the auxiliary member has a smaller dimension with increasing distance from a front face, and at least one of the first metal member and the second metal member is provided with an inclined face corresponding to the inclined face of the auxiliary member and inclined from the front face toward a back face.