Friction Stir Welding Retractable Pin Hole Elimination
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Solution Overview
Problem
The existing friction stir welding process faces challenges in achieving a satisfactory finish, particularly at the ends of the welded joint, as it often results in a weld hole that weakens the connection and increases the risk of corrosion and cracking, and the quality of the joint is compromised when using a retractable pin, which reduces the penetration depth and solidification of the material.
Innovation Solution
A friction stir welding process using a retractable pin that extends beyond the end of the welded joint, combined with a gradually thinned edge on the upper plate, allows for constant penetration depth and eliminates the weld hole by retracting the pin in a controlled manner, ensuring homogeneous mechanical characteristics of the welded joint over its entire length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a retractable pin is used to eliminate the weld hole, then the quality of the welded joint is improved, but the penetration depth and solidification of the material are reduced
Solution Approach 1:
The pin is designed to be retractable rather than stationary, allowing it to dynamically adjust its position. During welding, the pin extends to achieve full penetration depth and proper material solidification. At the end of the welded joint, the pin retracts to prevent material extrusion and weld hole formation. This dynamic adjustment resolves the contradiction by providing both deep penetration during welding and hole prevention at the joint end.
Solution Approach 2:
The method involves extending the welding path beyond the actual end of the welded joint. This preliminary extension allows the pin to complete its welding function with full penetration depth before the joint end is reached, then retract to prevent weld hole formation in the final section. The action is prepared in advance by planning the extended path, ensuring both penetration quality and end joint integrity.
2Manufacturing precision
If the welding path is extended beyond the end of the welded joint, then the weld hole is eliminated, but the welding time is increased
Solution Approach 1:
The welding path is extended slightly beyond the actual end of the welded joint - not by a large margin, but by a controlled amount sufficient to allow pin retraction without creating a weld hole. This partial extension achieves the goal of eliminating the weld hole while minimizing the additional welding time required. The extension is excessive only to the degree necessary for pin retraction, not beyond.
3Strength
If the pin penetrates deeply into the material, then the welding strength is improved, but material flows to the edge of the upper plate
Solution Approach 1:
The retractable pin allows dynamic control of penetration depth. During the main welding section, the pin extends to achieve deep penetration for strong welding. Near the end of the welded joint, the pin retracts to shallower depth, preventing softened material from flowing to the edge of the upper plate. This dynamic depth adjustment resolves the contradiction between achieving welding strength and preventing edge material flow.
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 production of a welded joint with improved quality and integrity by maintaining a consistent penetration depth and eliminating the weld hole, thus enhancing the mechanical characteristics and reducing the risk of corrosion and cracking at the joint ends.
Implementation Method 1
The friction of the welding device 3 on the plates 1, 2 is transformed into heat and causes a softening of the material of plates 1, 2, which then locally enters into a pasty state.
Data Source
AI summary
The invention relates to a process for the friction stir welding of two panels (20, 21), using a welding device (25) having a retractable pin (29), comprising the following steps: positioning the two panels (20, 21) so as to be in contact over an overlap region (24) and keeping them in the desired relative position after welding; bringing the welding device into contact with the upper panel at the start of the welded joint; longitudinally welding the two panels, by moving the welding device as far as the end of the welded joint; continuing to move the welding device (25) along a path extending beyond the end of the welded joint; and retracting the retractable pin (29) so as to prevent the appearance of a weld hole in a portion of the path of the welding device (25) extending beyond the end of the welded joint.