Laser Welding Heat Management for Nugget Consistency
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Solution Overview
Problem
Existing laser welding methods face challenges in maintaining consistent nugget size and stability when forming multiple nuggets sequentially, leading to irregular weld sections, especially at high speeds or with numerous nuggets in close proximity.
Innovation Solution
The method involves projecting a laser beam onto metallic workpieces in a way that reduces the input heat for each subsequent nugget by considering the remaining heat from previous nuggets, using a two-stage laser irradiation process to control heat distribution and solidification, and adjusting the irradiation intensity and speed to maintain consistent nugget formation along a virtual closed curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the same laser beam conditions are applied to each irradiation region when forming multiple nuggets sequentially, then the welding process is simple to operate, but the nugget size fluctuates and welding stability deteriorates
Solution Approach 1:
The patent applies different laser beam conditions (irradiation intensity, pulse width, or number of pulses) to different irradiation regions based on their local characteristics. Specifically, regions with higher remaining heat from previous nuggets receive lower irradiation intensity or fewer pulses, while regions with less remaining heat receive higher irradiation intensity or more pulses. This local adaptation ensures uniform nugget sizes across the weld line while maintaining operational simplicity through automated control.
2Productivity
If the laser beam is projected at high speed to form multiple nuggets, then productivity increases, but nugget size fluctuation becomes more prominent and welding reliability decreases
Solution Approach 1:
The patent dynamically adjusts laser beam parameters (irradiation intensity, pulse width, or number of pulses) for each irradiation region based on real-time or pre-calculated remaining heat conditions. This dynamic control allows the system to maintain welding reliability and nugget consistency even at high welding speeds, as the parameters are optimized for each specific location rather than using fixed settings throughout the weld line.
3Strength
If the laser beam irradiation intensity is increased to ensure complete melting, then welding strength improves, but excessive heat irradiation causes nugget size fluctuation and potential cracking
Solution Approach 1:
The patent changes multiple laser beam parameters (irradiation intensity, pulse width, number of pulses) in combination to achieve complete melting without excessive heat input. By adjusting these parameters based on remaining heat conditions at each irradiation region, the system ensures adequate welding strength while preventing harmful effects such as nugget size fluctuation and cracking. This multi-parameter control provides fine-tuned heat management for optimal weld quality.
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 approach stabilizes the welding process, suppresses nugget size fluctuations, and prevents excessive heat irradiation, resulting in a stable and uniform weld section with reduced crack formation and improved structural integrity.
Implementation Method 1
a laser beam is projected onto irradiation regions P1 to P3 that are in the same shape and located on a closed curve D such that each of the nuggets is formed along a circumference that is a virtual closed curve D
Implementation Method 2
the nuggets N1, N2, N3 are sequentially formed... size of the nugget tends to increase in an order of the nuggets N1 to N3
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 3A~3D
AI summary
A laser welding method includes: projecting a laser beam onto irradiation regions on plural metallic workpieces such that a weld section is formed when the workpieces are joined by laser welding, the weld section being formed of plural nuggets, and each of the irradiation regions being formed with each of the nuggets. The nuggets are sequentially formed by sequentially projecting the laser beam onto the irradiation regions that respectively correspond to the nuggets. The laser beam is projected onto each of the irradiation regions such that an amount of input heat from the laser beam that is projected onto each of the irradiation regions to the workpiece is reduced as the nuggets are sequentially formed.