Butt Laser Welding with Front and Back Keyholes Across Sheet Gaps
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Solution Overview
Problem
Conventional laser welding methods for butt welding metal sheets with a gap between them suffer from low energy efficiency due to energy wastage through the gap, resulting in incomplete contact and suboptimal mechanical properties of the weld joint.
Innovation Solution
A method involving the simultaneous emission of a first and second front laser beam and a back laser beam, with specific energy densities and spot configurations, to create keyholes and melt baths that maintain contact and efficiently weld metal sheets with a gap, ensuring effective energy absorption and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional single laser beam welding is used on metal sheets with a gap, then the welding process can be performed, but energy efficiency deteriorates significantly due to energy loss through the gap
Solution Approach 1:
The welding process is segmented into three distinct laser beam zones: two front laser beams that create keyholes in each metal sheet, and one back laser beam that bridges the gap and creates a connecting keyhole. This segmentation allows each beam to perform a specific function, preventing energy loss through the gap while maintaining manageable system complexity
Solution Approach 2:
The solution transitions from a single-sided (one-dimensional approach) welding method to a dual-sided (three-dimensional approach) method by introducing a back laser beam that acts from the opposite side of the joint. This dimensional change allows the welding energy to be applied from both directions, eliminating energy loss through the gap while the coordinated control of multiple beams maintains system manageability
2Ease of operation
If metal sheets are positioned with a gap for welding, then accessibility and setup are improved, but weld quality deteriorates due to incomplete contact and energy wastage
Solution Approach 1:
The two front laser beams first create keyholes in each metal sheet before the back laser beam acts to bridge the gap. This preliminary action of creating individual keyholes ensures proper positioning and preparation of each sheet, allowing the back beam to effectively connect them while maintaining both setup accessibility and weld quality
Solution Approach 2:
The back laser beam acts as an intermediary that bridges the gap between the two front laser beams' keyholes. It creates a connecting keyhole that fuses the two metal sheets, ensuring complete contact and energy transfer while allowing the sheets to be positioned with initial gap for accessibility
3Productivity
If high energy density is applied to weld through the gap, then welding speed is improved, but energy loss through the gap increases
Solution Approach 1:
Each laser beam is configured with specific energy density parameters optimized for its local function: the front beams create keyholes with controlled energy density, while the back beam uses optimized energy density to bridge the gap. This local optimization allows high welding speed without excessive energy loss, as each zone receives appropriately tailored energy input
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 enhances energy efficiency and mechanical properties of the weld joint by maintaining contact and optimizing energy absorption, even with gaps between the metal sheets, improving the quality and efficiency of the welding process.
Implementation Method 1
an important part of the energy of the laser beam is wasted since it passes through the gap and therefore does not interact with the sheets
Implementation Method 2
the energy of the laser beam is wasted since it passes through the gap and therefore does not interact with the sheets
Implementation Method 3
the energy of the laser beam is wasted since it passes through the gap and therefore does not interact with the sheets
Implementation Method 4
two further laser beams being intended for melting the metal sheets and for mixing the created weld pool
Data Source
AI summary
A method for butt laser welding two metal sheets includes providing a first metal sheet and a second metal sheet and butt welding the metal sheets along a direction of welding. The butt welding step includes simultaneously generating a first front keyhole in the first metal sheet, generating a second front keyhole in the second metal sheet, and generating a back keyhole in the first and second metal sheets. The first and second front laser beams and the back laser beam are configured in such a manner that at each moment in time, a solid phase region and/or a liquid phase region of the metal sheets remains between the first front keyhole and the back keyhole and between the second front keyhole and the back keyhole.