Laser Welding Spiral Locus Solid Phase Avoidance
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Solution Overview
Problem
Laser welding techniques face challenges in achieving uniform beads and reducing the generation of bubbles and pits due to the stirring effect of the laser beam on molten metal, particularly when using a spiral locus, which affects the quality and strength of the weld.
Innovation Solution
A laser welding method where the welding target is irradiated with a laser beam along a spiral locus, with the beam spot moving in a way that it avoids the liquid phase of the molten pool as much as possible, passing through the solid phase instead, and the interval coefficient of the spiral locus is controlled to optimize the heat input and reduce defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spiral locus is used for laser welding to improve positional shift and gap margin, then the welding robustness is improved, but bubbles and pits are generated due to the stirring effect of the laser beam on molten metal
Solution Approach 1:
Instead of allowing the laser beam to pass through the molten pool (conventional spiral welding), the invention inverts the approach by making the laser beam avoid the liquid phase entirely. The beam spot is controlled to pass only through the solid phase of the workpiece, thereby eliminating the harmful stirring effect that generates bubbles and pits while preserving the benefits of spiral locus welding.
Solution Approach 2:
The invention applies different irradiation strategies to different regions: the laser beam is directed to irradiate only the solid phase regions (front and rear sides of the molten pool) while deliberately avoiding the liquid phase region. This localized quality control ensures that heat is input into solid material to create molten metal, but the beam does not stir the molten pool, thus preventing defect formation.
2Object-generated harmful factors
If the laser beam passes through the molten pool to create a stirring effect, then gas release is promoted, but the bead uniformity deteriorates and bubbles are generated
Solution Approach 1:
The invention inverts the conventional approach by preventing the laser beam from passing through the molten pool. Instead of using the beam to stir and promote gas release, the beam is controlled to irradiate only solid phases, thereby achieving bead uniformity while gas release occurs through natural processes without harmful stirring.
Solution Approach 2:
The invention converts the potential harm of gas trapped in the molten pool into a benefit by allowing natural gas release without laser-induced stirring. By avoiding molten pool irradiation, the system prevents bubble formation while maintaining effective gas release through controlled solid phase heating and natural convection in the molten pool.
3Productivity
If the laser beam irradiates the molten pool, then the welding speed can be increased, but the generation of bubbles and pits increases
Solution Approach 1:
The invention inverts the conventional welding approach by controlling the laser beam to avoid the molten pool entirely. The beam spot is positioned to irradiate only the solid phase regions, enabling high welding speeds without the harmful stirring effect that generates bubbles and pits, thus decoupling welding speed from defect formation.
Solution Approach 2:
The laser beam performs preliminary heating of the solid phase material ahead of and behind the molten pool, preparing the material for welding without directly irradiating the molten pool. This preliminary action on solid phases enables efficient heat transfer and melting while avoiding the harmful effects of molten pool irradiation, even at high welding speeds.
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 method results in a uniform bead with reduced occurrence of bubbles and pits, enhancing the quality and strength of the weld, even in cases with gaps between metal plates, and allows for easier determination of welding conditions by operators with little experience.
Implementation Method 1
a welding target is irradiated with a laser beam so as to form a beam spot that moves relatively with respect to the welding target along a locus having a spiral shape
Implementation Method 2
The welding target is welded using the laser beam irradiated with
Data Source
AI summary
A welding target is irradiated with a laser beam so as to form a beam spot that moves relatively with respect to the welding target along a locus having a spiral shape rotating around a rotation center moving in a welding direction. The welding target is welded using the laser beam irradiated with. While the welding target is irradiated with the laser beam, the welding target is irradiated with the laser beam based on an interval coefficient which is a value indicating an overlapping degree of the locus having the spiral shape in the welding direction.