Friction Stir Welding Thin Metal Sheets Flat Disc Tool
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Solution Overview
Problem
Existing methods for joining thin metal sheets using friction stir welding face challenges such as restrictions on dimensional accuracy and difficulty in achieving precise positioning, leading to potential burn-through and distortion.
Innovation Solution
The method involves overlapping metal sheets with a predetermined width and using a rotating tool with a flat contact surface to generate frictional heat and pressure, preventing fusion and allowing for plastic flow, thereby maintaining joint strength and minimizing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If friction stir welding is used to join metal sheets, then joining strength is improved, but burn through and distortion occur
Solution Approach 1:
The invention changes the geometric parameters of the rotary tool from a conventional columnar shape with a pin to a flat disc shape without a pin. This parameter change modifies the friction stir welding process to prevent burn through and distortion while maintaining joining strength, as the flat disc configuration distributes heat and pressure more evenly across the joint area.
Solution Approach 2:
The invention uses a simple flat disc rotary tool that can be easily replaced rather than a complex columnar tool with pin. This disposable-like approach simplifies the tool design, reducing the risk of tool-induced distortion and burn through while maintaining effective joining capability.
2Manufacturing precision
If dimensional accuracy is restricted before joining, then joining precision is improved, but manufacturing complexity increases
Solution Approach 1:
The invention performs preliminary positioning by overlapping the metal sheets before applying the flat disc rotary tool. This preliminary action establishes the correct geometry without requiring strict pre-joining dimensional controls, simplifying the manufacturing process while maintaining precision.
Solution Approach 2:
The joining process is segmented into distinct stages: first overlapping the sheets to establish geometry, then applying the flat disc tool for joining. This segmentation allows each stage to be optimized independently, reducing overall manufacturing complexity.
3Strength
If a columnar rotary tool with pin is used, then frictional heat is generated for joining, but the thickness of joint portion decreases due to plunging
Solution Approach 1:
The invention inverts the conventional tool geometry from a columnar shape with a pin that plunges into the material to a flat disc shape that sits on the surface. This inversion prevents material displacement and thickness reduction while still generating the necessary frictional heat for joining through the flat contact surface.
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 approach enables the joining of thin metal sheets with improved dimensional accuracy and strength, reducing the risk of burn-through and distortion while maintaining the thickness of the joint portion, and preventing degradation of the external appearance.
Implementation Method 1
frictional heat is generated between the rotary tool and the materials to be joined
Implementation Method 2
heating and pressurizing the overlapping portion to form a joint
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
A first metal sheet (1) is placed on a backing metal plate (6), and an end portion of a second metal sheet (2) is placed on top of an end portion of the first metal sheet (1) such that the ends of the end portions are spaced apart from each other by a predetermined distance in side view. The end portions of the first and second metal sheets (1) and (2) are joined together by downwardly pressing a rotating rotary tool (4) onto the end portion of the second metal sheet (2) placed on top of the end portion of the first metal sheet (1) and by utilizing frictional heat and pressurizing force generated between the rotating tool and the first and second metal sheets (1) and (2).