Laser Welding Scan Pattern to Prevent Burn-Through in Metal Plates
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Solution Overview
Problem
Conventional laser welding methods face challenges in achieving sufficient joining strength between metal plates with large plate gaps, as increasing the joining region area often leads to 'burn through' defects, resulting in insufficient bonding.
Innovation Solution
A laser welding method that involves scanning with a laser beam along concentric circular loci, with emission intervals to cool and increase the viscosity of molten metal, preventing 'burn through' while maintaining a large joining region area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the area of the joining region is increased to ensure sufficient joining strength between metal plates, then the joining strength is improved, but the molten metal may detach and generate burn through defects
Solution Approach 1:
The patent applies periodic action by implementing intermittent laser irradiation with emission intervals. The laser beam irradiates the metal plates in periodic cycles, stopping irradiation at predetermined intervals to allow molten metal to cool and increase viscosity. This periodic on-off irradiation pattern enables the formation of a large joining region while preventing burn through by controlling the thermal state of the molten metal throughout the welding process.
2Length of stationary object
If the amount of molten metal is increased to bridge large plate gaps, then the gap bridging capability is improved, but the molten metal may hang down and detach causing burn through
Solution Approach 1:
The patent applies preliminary action by providing emission intervals before continuing laser irradiation. Before the laser beam resumes irradiating to generate additional molten metal for bridging gaps, it stops irradiation temporarily to allow the previously generated molten metal to cool and increase in viscosity. This preliminary cooling action stabilizes the molten metal structure, preventing it from hanging down and detaching, thereby enabling safe bridging of larger plate gaps.
3Productivity
If continuous laser irradiation is applied to melt metal plates, then the welding efficiency is improved, but the molten metal viscosity decreases causing burn through
Solution Approach 1:
The patent resolves the contradiction between welding efficiency and molten metal stability by implementing periodic action with emission intervals. The laser beam irradiates continuously but with predetermined interruptions, maintaining high overall irradiation duty cycles for efficiency while incorporating brief stopping periods to allow molten metal cooling. This periodic pattern prevents harmful detachment by periodically restoring molten metal viscosity without significantly reducing total welding productivity.
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 ensures sufficient joining strength between metal plates by preventing 'burn through' and optimizing the joining region area, reducing the risk of molten metal detachment and enhancing bonding quality.
Implementation Method 1
applying a laser beam to a surface of a plurality of metal plates superimposed on each other; melting the metal plates by scanning a position to be irradiated
Implementation Method 2
applying a laser beam to a surface of a plurality of metal plates superimposed on each other
Implementation Method 3
providing an emission interval at the time of shifting the scanning locus so that the irradiation on the surface of the metal plates with the laser beam is temporally stopped
Implementation Method 4
cool and increase the viscosity of molten metal
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
A laser welding method is provided to ensure a sufficient joining strength between metal plates (W1, W2) by increasing the area of a joining region while preventing "burn through" of a molten metal. In the laser welding method by applying a laser beam to a surface of multiple metal plates (W1, W2) superimposed on each other, a scanning locus with the laser beam is sequentially shifted from an inner circular scanning locus to an outer one in a predetermined joining region on the metal plates (W1, W2), and an emission interval is provided to temporally stop the metal-plate-surface irradiation when the scanning locus is shifted. Thus, every time the scanning locus is shifted, the molten metal due to the previous irradiation is cooled and increases its viscosity. Accordingly, the "burn through" is prevented regardless of increase of the area of the joining region, which results in a sufficient joining strength between the metal plates (W1, W2).