Friction Stir Welding Tool Dovetail Connection
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Solution Overview
Problem
In friction stir welding, tools with high melting points face issues such as heat transfer and torsional stress, leading to burning, biting, and detachment problems between the tool and holder, as well as loose fittings and inadequate rotational force transmission.
Innovation Solution
A tool design featuring a tool part and shank part with convex and concave sections that restrict movement around the axis of rotation while allowing parallel movement, secured by a cap or screw mechanism, to ensure reliable fixation and easy detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the tool and holder are assembled by shrinkage fitting or similar methods, then the fitting may become loose due to heating, but the initial fixation strength is improved
Solution Approach 1:
The connection interface is segmented into convex sections and concave sections that can move relative to each other in the axial direction while restricted in radial direction, allowing the tool to be divided into separable tool part and holder part that can be assembled and disassembled
Solution Approach 2:
The connection structure transitions from a static fixed fit to a dynamic adjustable fit, where the tool part can move axially relative to the holder during assembly and operation, adapting to thermal expansion and contraction while maintaining reliable connection
2Reliability
If the tool is securely fixed to prevent detachment, then rotational force transmission is improved, but the ease of detachment for tool replacement deteriorates
Solution Approach 1:
The connection structure allows dynamic movement in the axial direction for easy assembly and disassembly, while maintaining static restriction in the radial direction for reliable rotational force transmission during operation
Solution Approach 2:
The connection interface is segmented into convex and concave sections with orthogonal movement characteristics, separating the functions of easy detachment (axial movement) and reliable fixation (radial restriction) into different directional degrees of freedom
3Reliability
If the tool part is made of expensive high-performance material for high melting point welding, then the welding performance is improved, but the manufacturing cost increases
Solution Approach 1:
The tool is segmented into a tool part requiring high-performance material for welding contact and a holder part that can be made of inexpensive material, allowing selective material application only where necessary for performance
Solution Approach 2:
High-performance material is applied locally only to the tool part that contacts the workpiece and experiences high temperature and stress, while the holder part uses cost-effective materials, optimizing both performance and cost
Data Source
AI summary
A tool for friction stir welding includes a tool part, a shank part and a cap part. The tool part and the shank part have a hexagonal frustum-shaped concave section and a hexagonal frustum-shaped convex section to enable movement of the tool part with respect to the shank part in a direction parallel to an axis of rotation while movement of the tool part with respect to the shank part in a direction around the axis of rotation is restricted, by the hexagonal frustum-shaped concave section and the hexagonal frustum-shaped convex section of the tool part and the shank part are fitted to each other. After the hexagonal frustum-shaped concave section and the hexagonal frustum-shaped convex section are fitted to each other, by the tool part and the shank part being covered by the cap part, the tool part is fixed to the shank part.