Laser Lap Welding Galvanized Steel Protrusion Gap Zinc Vapor
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Solution Overview
Problem
Laser welding of galvanized steel sheets faces challenges such as welding failures due to vaporized zinc causing blowholes, and existing methods require modifications to parts designed for spot welding, affecting strength and impact resistance, and necessitating retesting and redesigning.
Innovation Solution
A laser lap welding method involving press-forming parts with elongated joining regions and forming ridge-shaped protrusions to create a gap for zinc vapor discharge, allowing for stable gap formation and equivalent joining strength to spot welding without altering the layout of unit spots, enabling the use of existing design data and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protrusions are formed on galvanized sheets to discharge zinc vapor during laser welding, then welding quality is improved, but part design complexity increases and existing spot-welding designs cannot be directly utilized
Solution Approach 1:
The invention changes the geometric parameters of the protrusions (height, shape, spacing) to optimize zinc vapor discharge while maintaining compatibility with existing part designs. By adjusting these parameters, the system achieves reliable welding without requiring complete redesign of the parts.
Solution Approach 2:
The protrusions are pre-formed on the galvanized sheets before welding to create predetermined discharge paths for zinc vapor. This preliminary structuring ensures that when laser welding is performed, the vapor has already-defined escape routes, preventing blowholes without requiring complex real-time control systems.
2Reliability
If welding positions are changed to accommodate protrusions for laser welding, then zinc vapor discharge is improved, but strength performance and impact resistance change requiring retesting
Solution Approach 1:
The invention applies local modifications (protrusions) only at specific locations where zinc vapor discharge is needed, rather than changing the overall part design or welding positions. This localized approach maintains the structural integrity and strength performance of the original design while enabling effective vapor discharge at critical points.
3Productivity
If laser welding is introduced as alternative to spot welding, then processing speed is improved, but modifications to part design are required affecting accumulated design data
Solution Approach 1:
The invention makes the protrusion structures serve multiple functions: they enable zinc vapor discharge for laser welding compatibility while maintaining compatibility with existing spot-welding design data and part geometries. This multi-functionality allows the same part design to benefit from both welding methods or transition between them without complete redesign.
4Productivity
If continuous laser welding is performed on galvanized sheets, then welding efficiency is improved, but blowholes occur due to trapped zinc vapor
Solution Approach 1:
The invention segments the welding path into discrete unit spots that are welded sequentially rather than as a continuous operation. Between these unit spots, the protrusions provide vapor discharge paths. This segmentation allows efficient welding while preventing blowholes by clearing vapor at regular intervals along the weld path.
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
Achieves stable zinc vapor discharge and equivalent joining strength to spot welding, allowing for the introduction of laser welding as a cost-effective alternative with minimal power consumption and no non-effective shunt current issues, while maintaining existing design data utilization.
Implementation Method 1
irradiating a laser (2a) onto one surface of the overlapped joining regions of the two parts such that the overlapped joining regions are fused and welded (2) by energy of the laser
Implementation Method 2
zinc gas produced with fusing is discharged through the gap
Data Source
AI summary
A laser lap welding method for parts made of galvanized steel sheet includes steps of press-forming two parts from galvanized steel sheet such that the two parts include elongated joining regions to be welded together on mutually opposed surfaces thereof and a plurality of protrusions are formed on at least any one of the joining regions of the two parts at predetermined intervals in a longitudinal direction of the joining region; retaining the two parts in a state in which the joining regions are overlapped one on the other such that a gap according to a height of the protrusions is formed between the joining regions; and irradiating a laser onto one surface of the overlapped joining regions of the two parts such that the overlapped joining regions are fused and welded by energy of the laser, and zinc gas produced with fusing is discharged through the gap.