Laser Weld Start-End Heating to Prevent Spatter and Craters
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Solution Overview
Problem
Existing laser welding methods suffer from defects such as welding spatter and craters at the start and end of the weld seam due to sudden temperature gradients, which degrade the quality of the weld seam.
Innovation Solution
A method involving a main laser beam and one or more secondary laser beams is used in the start and end regions of the weld seam to control temperature gradients, avoiding spatter and craters by uniformly heating the surrounding area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the laser beam is activated at the beginning of the welding process with concentrated power on the main spot, then the welding speed and efficiency are improved, but a steep temperature gradient forms causing welding spatter and reduced weld seam quality
Solution Approach 1:
The laser beam is divided into a main spot and one or more secondary spots. The main spot concentrates power for efficient welding, while secondary spots distribute additional power to surrounding areas to reduce temperature gradients and prevent spatter, thus resolving the contradiction between welding speed and quality.
Solution Approach 2:
Different regions of the workpiece receive different power densities: the main spot provides high power density for rapid melting and welding progression, while secondary spots provide lower power density to surrounding areas to create a more gradual temperature gradient, preventing spatter formation.
2Loss of time
If the laser beam is switched off at the end of the welding process, then the welding cycle time is reduced, but a steep temperature gradient causes welding craters that significantly reduce weld seam quality
Solution Approach 1:
Before switching off the laser beam at the end of welding, secondary spots are activated to pre-heat the surrounding area and reduce the temperature gradient. This preliminary action prevents crater formation when the beam is switched off, maintaining weld quality without extending the welding cycle time.
Solution Approach 2:
The secondary spots apply a counter-action to the rapid cooling that would otherwise occur when the main beam is switched off. By heating the surrounding area in advance, they counteract the steep temperature gradient that causes crater formation, thus preventing quality degradation.
3Productivity
If the entire laser power is concentrated on the main spot throughout the welding process, then the welding process is carried out in the shortest possible time, but defects occur at the start and end regions of the weld seam
Solution Approach 1:
The laser beam configuration is made dynamic: the main spot operates alone in the middle region for high-speed welding, while secondary spots are activated in the start and end regions to prevent defects. This dynamic adjustment maintains both high productivity and reliable weld quality throughout the entire weld seam.
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 weld seam quality by preventing defects at the seam ends while allowing efficient welding with high precision and speed.
Implementation Method 1
the laser beam is moved along a joining zone of the components, wherein the material of the components, which in particular consist of metal material, is melted in the region of the joining zone
Implementation Method 2
a second, subordinate laser beam is provided, which heats a trailing region of the melt
Data Source
AI summary
A method for laser welding. A weld seam is produced by a laser from a start region to a target region on a target by targetedly applying laser light to the target from the start region to the target region. The laser light in the start region and/or in the target region of the weld seam is split into a main spot and at least one secondary spot for heating a surrounding area of the incidence region of the main spot on the target, and only one main spot is formed between the start region and the target region during the welding process, which main spot is guided along the weld seam on the target.