Segmented Laser Beam Welding to Prevent Weld Seam Humping
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Solution Overview
Problem
Conventional laser beam joining methods face limitations in process speed due to the occurrence of periodic irregularities, known as 'humping', which leads to material accumulation and deficits, resulting in a weakened connection and increased risk of leaks, particularly in thin materials like those used in bipolar plates for fuel cells.
Innovation Solution
The method involves dividing the weld seam into sections, allowing for higher process speeds by producing each section sequentially with intermediate interruptions, and then merging them to form a continuous seam, ensuring material bonding and gas-tightness through precise alignment and overlapping strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the process speed is increased above the critical limit value, then productivity is improved, but periodic irregularities (humping) occur in the weld seam leading to material accumulations and deficits
Solution Approach 1:
The weld seam is divided into multiple individual weld seam sections that are produced sequentially with intermediate interruptions. Each section is created as a separate welding operation, allowing the process speed to be optimized for each segment while avoiding the cumulative humping effect that occurs in continuous welding at high speeds.
Solution Approach 2:
The welding process uses periodic interruption between weld seam sections rather than continuous welding. This periodic action allows the material to cool and reset between sections, preventing the periodic irregularities that accumulate during continuous high-speed welding, while still maintaining overall high productivity.
2Productivity
If the process speed is increased to reduce cycle time, then productivity is improved, but the risk of leaks increases due to humping-induced material deficits
Solution Approach 1:
By segmenting the weld seam into discrete sections, each section can be controlled to achieve complete penetration and gas-tightness independently. The intermediate interruptions allow for proper pool solidification and overlap formation, ensuring reliability even at high process speeds.
Solution Approach 2:
Each weld seam section is produced as a preliminary discrete unit with controlled parameters ensuring gas-tightness before moving to the next section. This preliminary action approach ensures that each segment meets quality requirements before proceeding, maintaining overall reliability.
3Manufacturing precision
If the process speed is limited to avoid humping, then weld seam quality is maintained, but the number of welding systems must be increased for large-scale production
Solution Approach 1:
The segmentation of the weld seam allows a single welding system to produce multiple sections sequentially with interruptions, effectively replacing the need for multiple parallel welding systems while maintaining quality standards through controlled section-by-section production.
Solution Approach 2:
The periodic interruption strategy enables a single welding system to operate at higher effective throughput by alternating between welding sections and interruption periods, eliminating the need for multiple continuous welding systems while maintaining quality.
4Stability of the object's composition
If continuous welding is used to produce a long weld seam, then the connection is continuous, but periodic irregularities occur after the start phase
Solution Approach 1:
The weld seam is segmented into multiple sections that are produced sequentially. The overlap regions between sections ensure continuity of the connection, while the intermediate interruptions prevent the accumulation of periodic irregularities that occur in continuous welding.
Solution Approach 2:
Periodic interruptions are introduced between weld seam sections to reset the welding process conditions. This periodic action prevents the development of periodic irregularities while the overlap regions maintain the continuity of the welded connection.
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 increases process speed while avoiding humping, enabling the production of long, continuous, and gas-tight weld seams, reducing the risk of leaks and thermal distortion, and allowing for the use of thinner materials in large-scale production.
Implementation Method 1
laser beam joining of at least two joining partners, in which a laser beam device produces a continuous weld seam
Implementation Method 2
the laser beam moves continuously along the application path at a process speed, as a result of which the weld seam is formed
Data Source
AI summary
A method for laser beam joining of at least two joining partners, in which a laser beam device produces a continuous weld seam along an application path with a preferably very long path length. Irregularities in the weld seam due to high process speeds are avoided as follows: in a first process step, at least two weld seam sections spaced apart from one another in the longitudinal direction of the path, are respectively produced with an intermediate weld seam interruption. In a second process step the laser beam device produces in each weld seam interruption a further weld seam section, such that all weld seam sections merge together without interruptions, in particular with formation of the continuous weld seam.