Laser Weld Scanning Intervals to Prevent Burn-Through
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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 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 is more likely to detach and cause burn through defects
Solution Approach 1:
The laser beam irradiation is applied periodically with emission intervals between successive irradiations. The molten pool is irradiated, then allowed to cool and solidify partially, then irradiated again. This periodic action allows the molten metal to maintain sufficient viscosity to bridge gaps without detaching, preventing burn through while still achieving adequate joining strength through cumulative heating and bonding.
Solution Approach 2:
The laser beam performs preliminary heating and melting of the metal plates before the molten metal can detach. By applying heat in advance and maintaining the molten state with controlled irradiation intervals, the metal is prepared to flow and bridge the gap between plates before gravitational detachment can occur, ensuring both gap bridging and burn through prevention.
2Length of moving object
If the amount of molten metal is increased to bridge large plate gaps, then the gap bridging capability is improved, but the burn through defect becomes more likely
Solution Approach 1:
The periodic irradiation with emission intervals allows the molten pool to maintain a controlled volume of molten metal throughout the process. The metal is melted, allowed to flow and bridge the gap, then partially solidifies during the interval, preventing excessive accumulation that would lead to burn through while maintaining sufficient molten metal to bridge large gaps.
Solution Approach 2:
The laser beam parameters (irradiation time, intensity, and intervals) are adjusted to control the amount of molten metal generated. By changing the temporal parameters of laser application rather than continuously maximizing heat input, the process generates just enough molten metal to bridge gaps while avoiding the excess that causes burn through defects.
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 reducing 'burn through' occurrences and enhancing the bonding area, even with increased joining region sizes.
Implementation Method 1
irradiating a surface of metal plates with a laser beam; melting the metal plates to form a molten pool
Implementation Method 2
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 3
providing an emission interval at the time of shifting the scanning locus so that irradiation on the surface of the metal plates with the laser beam is temporally stopped; cooling the molten pool; increasing the viscosity of the molten metal
Data Source
AI summary
A laser welding method is provided to ensure a sufficient joining strength between metal plates 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 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, 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.