Laser Weld Nugget Pattern for Crack Resistance
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Solution Overview
Problem
Laser welding methods face challenges in achieving consistent weld quality due to stress concentration at the ends of straight-line welds, leading to potential cracking and reduced weld strength, especially when compared to circular or circumferential welds of the same size.
Innovation Solution
A welding method that forms a virtual closed curve of nuggets along the welding objects with a diameter-to-pitch ratio between ½ and 1, ensuring the base material is sandwiched between adjacent nuggets, thereby inhibiting crack progression and enhancing weld strength, while maintaining stability regardless of the welding orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser welding is performed in a straight line, then welding speed is high and processing distortion is minimal, but stress concentrates at the end portions leading to poor weld quality consistency
Solution Approach 1:
The weld is divided into multiple discrete nuggets arranged along a virtual closed curve rather than forming a continuous straight-line weld. This segmentation creates multiple stress distribution points throughout the weld zone, preventing stress concentration at single end portions and improving weld quality consistency while maintaining high welding speed through efficient laser processing.
2Strength
If a circular or circumferential weld is formed, then stress distribution is improved, but weld strength is reduced compared to optimized nugget arrangements
Solution Approach 1:
Instead of uniform circular welds, the invention employs nuggets with specific diameter-to-pitch ratios (0.5 to 1.0) arranged along a virtual closed curve. This creates non-uniform local characteristics where nugget size and spacing are optimized to simultaneously achieve excellent stress distribution throughout the weld zone and maximum weld strength, surpassing both straight-line and conventional circular weld approaches.
3Reliability
If nuggets are arranged with large diameter-to-pitch ratio, then crack progression is inhibited, but welding time increases
Solution Approach 1:
The invention optimizes the diameter-to-pitch ratio parameter within the specific range of 0.5 to 1.0, achieving the optimal balance between crack resistance and welding efficiency. This parameter optimization ensures sufficient base material between adjacent nuggets to inhibit crack progression while maintaining compact nugget arrangement that minimizes the number of welding points and reduces total welding time.
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 significantly improves weld strength by preventing crack propagation and ensuring equivalent strength to horizontal welds, even when performed vertically, while preventing protrusions and maintaining weld quality with die-cast materials.
Implementation Method 1
performing laser welding
Implementation Method 2
a weld is typically formed in a straight line by scanning laser light in a straight line
Data Source
AI summary
A welding method for joining together a plurality of welding objects by overlapping the plurality of welding objects and performing laser welding includes forming a weld by forming a plurality of nuggets along a virtual closed curve on the welding objects, by laser welding. A ratio of a diameter of the nuggets to a pitch dimension between the nuggets that are adjacent to each other is larger than ½ and no more than 1.