Annular Laser Welding of Thin Metal Plates for Uniform Joint Strength
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Solution Overview
Problem
Existing methods for joining thin metal plates, such as copper foil on a printed circuit board, to thicker base materials like a busbar face challenges in achieving sufficient welding strength due to differences in plate thickness, leading to directional weaknesses and potential damage from external forces, as well as issues with heat affecting insulating materials.
Innovation Solution
A laser welding method involving continuous irradiation along an annular welding schedule line with a single-mode fiber laser, where the laser light moves and vibrates to form concentric annular welding lines, ensuring uniform heat distribution and preventing burn-through, thereby enhancing welding strength without directionality and minimizing damage to insulating materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single-mode and continuous-wave fiber laser is used for joining thin metal plate to base material, then welding strength is improved, but directional weaknesses occur and the thin metal plate is susceptible to damage from external forces
Solution Approach 1:
The welding process is segmented into multiple passes with different parameters. The first pass uses lower power to create a shallow weld, and the second pass uses higher power to create a deeper weld. This segmentation allows the thin metal plate to be joined to the base material with sufficient strength while distributing the heat input to prevent directional weaknesses and improve resistance to external forces from any direction.
2Strength
If high heat input laser light is used to weld laminated metal plates, then welding strength is improved, but the insulating material is damaged by heat
Solution Approach 1:
The laser welding process is performed in periodic stages with different power levels. The first stage uses lower power to create an initial weld, and the second stage uses higher power to deepen the weld. This periodic action with controlled heat input achieves sufficient welding strength while preventing excessive heat accumulation that would damage the insulating material.
3Area of stationary object
If laser irradiation position is moved in a spiral shape, then welding coverage is improved, but the entire inside of the welding schedule line is not fully welded
Solution Approach 1:
The welding process is divided into multiple passes, with each pass covering a specific area. The first pass creates a shallow weld with lower power, and the second pass creates a deeper weld with higher power. This segmentation ensures that the entire inside of the welding schedule line is fully welded with both passes contributing to complete coverage and penetration.
Solution Approach 2:
The laser beam is applied in two sequential passes rather than attempting to achieve complete weld penetration in a single pass. The first pass provides partial welding with lower power, and the second pass provides additional welding with higher power, ensuring the entire inside of the welding schedule line is fully welded without excessive heat input in any single pass.
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 provides robust joining strength that withstands external forces from any direction, maintains the integrity of insulating materials, and prevents strain on thin metal plates, resulting in a durable and efficient welding process.
Implementation Method 1
forming a welding line such that a continuous irradiation with a laser light from a fiber laser is performed while moving the laser light along the welding schedule line
Implementation Method 2
while vibrating the laser light across the welding schedule line
Data Source
AI summary
A welding method includes overlapping a thin metal plate with a base material, and setting an annular welding schedule line on a welding schedule portion of the thin metal plate; forming a welding line such that a continuous irradiation with a laser light from a fiber laser is performed while moving the laser light along the welding schedule line, and while vibrating the laser light across the welding schedule line; and setting a length of the welding line such that an entire inside of the welding schedule line is welded.