Lap Laser Welding of Aluminum Cast Plates With Molten Pool Stirring
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Solution Overview
Problem
Lap welding of metal plates involving aluminum alloy casting often results in large blow holes due to gas bubbles, degrading the quality of the welding part, and existing methods to prevent this reduce productivity.
Innovation Solution
A laser welding method that uses a first laser beam to form a molten pool and a second laser beam with a higher scanning speed to stir and miniaturize bubbles, preventing large blow holes without extending the molten pool unnecessarily, thus maintaining productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the laser beam continuously irradiates the molten pool to prevent rapid cooling and ensure bubble discharge time, then the quality of welding part is improved, but the productivity decreases due to long processing time
Solution Approach 1:
The patent divides the laser beam irradiation process into two distinct stages: a melting step with the first laser beam to create the molten pool, and a stirring step with the second laser beam to agitate and break bubbles. This segmentation allows each stage to be optimized independently, resolving the contradiction between ensuring quality (through adequate bubble discharge time) and maintaining productivity (through faster processing).
Solution Approach 2:
The patent employs periodic action by using the second laser beam to repeatedly scan and stir the molten pool at high speed during the stirring step. This periodic stirring action continuously breaks up large bubbles into smaller ones and promotes gas discharge, enabling quality improvement without requiring excessively long total processing time.
2Manufacturing precision
If a second laser beam with higher scanning speed is used to stir the molten pool and miniaturize bubbles, then the welding quality is improved by reducing large blow holes, but the device complexity increases
Solution Approach 1:
The patent applies universality by using laser beams for multiple functions: the first laser beam performs melting, while the second laser beam performs stirring and bubble disruption. Both steps use the same fundamental tool (laser beam) but with different parameters, avoiding the need for entirely different equipment and reducing overall system complexity despite the multi-step process.
Solution Approach 2:
The patent resolves device complexity by changing parameters of the laser beam system rather than adding fundamentally different equipment. The second laser beam uses higher scanning speed and different irradiation patterns compared to the first laser beam, achieving the stirring function through parameter adjustment rather than mechanical complexity.
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 the generation of large blow holes in the welding part, enhancing the quality and strength of the weld while minimizing productivity losses.
Implementation Method 1
a melting step of scanning and irradiating circularly a superimposed part made by superimposing the plurality of metal plates with a first laser beam so as to form a molten pool made from the plurality of molten metal plates
Implementation Method 2
a stirring step of scanning and irradiating circularly the molten pool with a second laser beam having a scanning speed faster than a scanning speed of the first laser beam so as to stir the molten pool
Data Source
AI summary
In a laser welding method, generation of relatively large blow holes in a welding part is prevented while decrease in productivity is reduced. The laser welding method for lap welding, using a laser beam LB, of a plurality of metal plates and including an aluminum alloy cast plate includes: a melting path of scanning and irradiating circularly a superimposed part of the aluminum alloy plate and the aluminum alloy cast plate with a first laser beam LB1 to form a molten pool of the molten aluminum alloy plate and the molten aluminum alloy cast plate; and a stirring path of scanning and irradiating circularly the molten pool with a second laser beam LB2 having a scanning speed V2 faster than a scanning speed V1 of the first laser beam LB1 to stir the molten pool.