Arc Weld Initiation Using Laser-Formed Molten Pool
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Solution Overview
Problem
Conventional arc welding techniques face challenges in achieving uniform weld quality and efficiency, particularly at the initiation point, leading to potential discontinuities and increased processing time due to the need for subsequent grinding operations.
Innovation Solution
A method involving a secondary melting device to form a molten weld pool, followed by a primary welding device initiating the weld while the secondary device is deactivated, with a barrier protecting it from thermal radiation, allowing for continuous welding along the joint without reactivating the secondary device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional arc welding is used to create a weld pool, then welding can be performed, but the weld pool is non-uniform and contains metallic phases and gas bubbles, reducing weld quality
Solution Approach 1:
The invention uses a laser beam to pre-heat and melt the workpiece material before the arc welding process begins, creating a uniform molten pool. This preliminary action ensures the material is in a homogeneous molten state, eliminating metallic phases and gas bubbles that would otherwise be present in conventionally initiated weld pools.
Solution Approach 2:
The invention changes the thermal state parameters of the workpiece material by using laser heating to achieve a controlled molten pool temperature and uniform distribution before arc initiation. This parameter change from solid to uniform liquid state improves weld pool homogeneity and quality.
2Productivity
If conventional arc welding initiates a weld, then welding can proceed, but a local bead forms at the initiation point that requires grinding, increasing processing time
Solution Approach 1:
The laser beam creates a clean, uniform molten pool initiation point without forming a protruding bead. By pre-melting the material uniformly before arc contact, the welding process starts cleanly without requiring subsequent grinding operations to remove initiation beads, thus eliminating additional processing time.
3Strength
If conventional arc welding is used, then welding can be performed, but discontinuities in the weld may occur, adversely impacting joint strength and fatigue performance
Solution Approach 1:
The laser pre-heating and initial melting creates a uniform, contamination-free molten pool that eliminates the formation of discontinuities such as metallic phases and gas bubbles. This preliminary uniform molten state ensures continuous, high-quality weld metal deposition throughout the welding process, improving both joint strength and fatigue performance.
Solution Approach 2:
By changing the thermal parameters through laser pre-heating, the invention achieves a controlled, uniform molten pool temperature distribution that prevents discontinuity formation. This parameter control ensures homogeneous material mixing and continuous weld metal solidification, eliminating weak points in the joint.
4Manufacturing precision
If a laser beam is used to pre-heat the workpiece, then weld initiation quality improves, but the secondary melting device is exposed to thermal radiation from the welding arc
Solution Approach 1:
The invention extracts or removes the secondary melting device (laser) from the high-temperature arc zone by using a shutter mechanism. The shutter closes to block thermal radiation from the welding arc, protecting the laser optics and components from damage while allowing the laser to perform its pre-heating function before arc initiation.
Solution Approach 2:
The shutter acts as an intermediary protective element between the secondary melting device and the welding arc. It selectively blocks thermal radiation when the arc is active, allowing the laser system to be positioned close to the workpiece for effective pre-heating while preventing harmful radiation exposure during welding.
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 enhances weld quality by initiating the weld in hot, homogeneous metal, reducing discontinuities and eliminating the need for grinding, thus accelerating the welding process and improving joint strength and fatigue performance.
Implementation Method 1
activating a secondary melting device, such as a laser, to form a molten weld pool in the workpiece
Implementation Method 2
activating a primary welding device, such as a gas metal arc welding torch, to initiate a weld in the weld pool
Implementation Method 3
The deactivated secondary melting device is protected from thermal radiation emitted by the activated primary welding device
Data Source
AI summary
A weld is formed in a workpiece such as a pipeline by first activating a melting device, such as a laser, to form a molten weld pool in the workpiece and then activating a welding device, such as a GMAW torch, to initiate a weld in the weld pool. The weld therefore incorporates the weld pool homogeneously. Relative movement between the activated welding device and the workpiece continues and completes the weld while the melting device remains deactivated.