Laser Beam Joining Profile to Prevent Cracks and Air Bubbles
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Solution Overview
Problem
Conventional methods of joining metal members using laser beams often result in rapid temperature changes, leading to cracks and air bubbles in the joined member, which decreases the strength of the joint.
Innovation Solution
A method of manufacturing a joined member by irradiating a laser beam with a central portion of higher energy intensity and a peripheral portion of lower energy intensity, where the peripheral portion's length in the scanning direction is longer than in the perpendicular direction, to suppress temperature changes and improve bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a laser beam with high energy intensity is used to melt metal members for joining, then the joining strength is improved, but rapid temperature changes cause cracks and air bubbles that decrease the joined member strength
Solution Approach 1:
The laser beam is designed with non-uniform energy distribution where the peripheral portion has lower energy intensity than the central portion. This local quality variation allows the center to provide sufficient melting energy while the periphery suppresses rapid temperature changes, preventing cracks and air bubbles in the joined member.
Solution Approach 2:
The energy intensity distribution of the laser beam is changed from uniform to non-uniform, with the peripheral portion having lower energy intensity. This parameter change in energy distribution resolves the contradiction by providing controlled heating that achieves both strong joining and prevents thermal damage.
2Reliability
If the peripheral portion length in scanning direction is increased to suppress temperature changes, then crack and air bubble generation is reduced, but the energy consumption may increase
Solution Approach 1:
The energy intensity in the peripheral portion is optimized to be lower than the central portion but not zero, and the length ratio between scanning direction and perpendicular direction is controlled. This parameter optimization achieves reliable joining while controlling energy consumption by preventing excessive heating in the peripheral region.
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 effectively reduces the generation of cracks and air bubbles, enhances the strength of the joined member, and allows for efficient energy consumption while improving bond strength and liquid-tightness, particularly suitable for vehicle components.
Implementation Method 1
irradiating and melting an end portion on a joining side of the first metal member, while the first metal member is disposed adjacent to at least a portion of the second metal member, by irradiating a heat source while scanning
Implementation Method 2
irradiating and melting an end portion on a joining side of the first metal member
Data Source
AI summary
Provided is a method of manufacturing a joined member by joining a first metal member and a second metal member, the method including: melting an end portion on a joining side of the first metal member, while the first metal member is disposed adjacent to at least a portion of the second metal member, by irradiating the heat source while scanning, the heat source irradiated to the end portion on the joining side of the first metal member has a central portion and a peripheral portion located at a periphery of the central portion and having energy intensity lower than that of the central portion, and in the peripheral portion, a length in a scanning direction of the heat source is longer than a length in a direction perpendicular or substantially perpendicular to the scanning direction of the heat source.