Laser Weld Pool Beam Shaping for Void-Free Joints
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Solution Overview
Problem
Laser welding of metallic members often results in void formation within the welded joint, which compromises joint strength and is difficult to detect through appearance inspection.
Innovation Solution
A laser welding method and device that utilize a combination of main and sub-beams, where the sub-beam is emitted to escape voids from the molten weld pool before solidification, using a diffractive optical element to shape the beams and control the temperature distribution, ensuring voids are minimized in the solidified joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single high-power laser beam is used for welding, then welding speed and productivity are improved, but void formation increases and joint strength deteriorates
Solution Approach 1:
The laser beam is divided into multiple beams (main beam and sub-beams) with different power densities. The main beam provides high power density for rapid melting and welding, while sub-beams provide lower power density to prevent excessive void formation. This segmentation allows simultaneous achievement of high welding speed and high joint strength by distributing the heating function across multiple beams with differentiated roles.
2Productivity
If laser welding is performed to achieve high joint strength, then productivity is improved, but void formation occurs and reliability deteriorates
Solution Approach 1:
Different regions of the workpiece receive different power densities through the main beam and sub-beams. The main beam targets the center region for rapid melting, while sub-beams target peripheral regions to control solidification and prevent void formation. This local differentiation of power density ensures high welding efficiency while maintaining weld quality and reliability by addressing void formation in specific critical regions.
3Speed
If high power density laser beam is used, then welding speed increases, but void formation increases and becomes harder to detect
Solution Approach 1:
The invention converts the potentially harmful effect of void formation into a beneficial process feature. By using sub-beams with lower power density, the system creates controlled fluid flow in the molten pool that actively promotes void escape during solidification. This transforms the void formation issue into a self-cleaning mechanism where voids are generated but then systematically removed, making the process inherently more reliable and reducing inspection difficulty.
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
The method effectively reduces void formation, enhancing joint strength and allowing for more reliable inspection and quality control by maintaining the molten weld pool state longer, thereby reducing the number of voids in the welded part.
Implementation Method 1
forming a molten weld pool by emitting laser light including a main power region and a sub-power region onto a workpiece
Implementation Method 2
the sub-beam is emitted onto the workpiece such that a void formed inside the molten weld pool escapes to outside of the molten weld pool before the molten weld pool becomes solidified
Data Source
AI summary
A laser welding method includes: forming a molten weld pool by emitting laser light including a main power region and a sub-power region onto a workpiece, the main power region including at least one main beam, the sub-power region including at least one sub-beam having a lower power density than power density of the main beam; and solidifying the molten weld pool. The sub-beam is emitted onto the workpiece such that a void formed inside the molten weld pool escapes to outside of the molten weld pool before the molten weld pool becomes solidified.