Double-Acting Friction Stir Spot Welding Clamp for Thick Weld Regions
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Solution Overview
Problem
Existing double-acting friction stir spot welding methods struggle to create thick, strong welds with a clear boundary between stirred and non-stirred material, leading to potential weaknesses in the welded joint.
Innovation Solution
A holding jig with a cylindrical clamp member featuring an inclined surface that forms a concave region, combined with a backing member having a circular concave portion, allows for the filling of material to create thickened welds on both surfaces of the workpiece, with the inclined surface on the clamp member and the concave portion on the backing member ensuring the boundary between stirred and non-stirred material is within the thickened region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional clamp member with a flat pressing surface is used, then the workpiece can be held stably, but a thick region cannot be formed and the boundary between stirred and non-stirred material becomes exposed, reducing joint strength
Solution Approach 1:
The pressing surface of the clamp member is designed with a specific shape: a flat central portion and an inclined peripheral portion. This local differentiation allows the central flat area to provide stable holding while the inclined peripheral area creates the thick region that covers the boundary between stirred and non-stirred material, thereby improving joint strength without compromising stability
Solution Approach 2:
The pressing surface transitions from a two-dimensional flat surface to a three-dimensional shape with height variation. The inclined peripheral portion creates a height difference that forms the thick region, adding a vertical dimension to the pressing surface geometry to achieve both stable holding and boundary coverage
2Reliability
If the pressing surface is made larger to improve holding stability, then the workpiece is better supported, but the device complexity increases
Solution Approach 1:
The shape parameters of the pressing surface are optimized by defining specific geometric features: a flat central portion with a predetermined diameter and an inclined peripheral portion with a controlled slope. This parameter-based design achieves stable holding and thick region formation without requiring complex additional structures
3Strength
If the rotary tool is pressed deeply into the workpiece to create strong welds, then welding strength improves, but the boundary between stirred and non-stirred material becomes exposed and weak
Solution Approach 1:
The clamp member's inclined peripheral portion is designed in advance to create a thick region that will cover the boundary between stirred and non-stirred material. This preliminary shaping action ensures that when the rotary tool creates the weld, the boundary is already positioned within the thick region, preventing exposure and weakness
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
This configuration enhances the strength and rigidity of the welded joint by forming thick regions on both surfaces of the workpiece, reducing the likelihood of breakage and improving the joint's resistance to tensile loads.
Implementation Method 1
The pin member and the shoulder member can rotate and advance/retract independently. These rotary tools are pressed (press-fitted) into workpieces such as a metal material. The workpieces are softened and stirred by using frictional heat with the workpieces, thereby welding the workpieces to each other.
Implementation Method 2
a concave region whose periphery is covered with the clamp member is formed on the distal end portions of the rotary tools by aligning the contact surface of the shoulder member with the upper edge of the inclined surface. By moving the rotary tool forward and backward with respect to the workpiece in this state, the entire concave region can be filled with the material constituting the workpiece.
Data Source
AI summary
In a double-acting friction stir spot welding device or a double-acting friction stir spot welding method, a pin member and a cylindrical shoulder member that rotates around the axis of the pin member are used as rotary tools, and a clamp member that has a cylindrical shape positioned so as to surround the outside of the shoulder member and is configured to press a workpiece from an obverse surface with an annular pressing surface of the distal end is used as a holding jig. The clamp member has an inclined surface that is adjacent to the inner edge portion of the pressing surface and inclined so as to reduce the inner diameter of the clamp member toward the back side as viewed from the pressing surface.