Precoated Sheet Laser Ablation to Prevent Weld-Zone Build-Up
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Solution Overview
Problem
The buildup of precoating material during laser ablation of precoated steel sheets for welding leads to protrusions, which cause stacking and handling issues, can be brittle and break off, introducing unwanted constituents into the weld, and disrupts weld tracking systems, resulting in reduced weld quality.
Innovation Solution
A method using a protective surface with a dihedral angle to redirect ejected precoating material away from the sheet, combined with a gas jet to carry and ablate the material, and an aspiration nozzle to remove any remaining material, significantly reducing the build-up volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser ablation is used to remove precoating material, then the precoating is effectively removed to prevent weld contamination, but material accumulates on the edge of the removal zone creating a build-up
Solution Approach 1:
A protective surface is introduced as an intermediary element between the laser beam and the precoated sheet. This protective surface intercepts the precoating material ejected during laser ablation and redirects it away from the sheet, preventing build-up formation while allowing the laser ablation process to proceed effectively
Solution Approach 2:
The ejected precoating material, which would normally be harmful by creating build-up, is converted into a beneficial flow pattern. By positioning the protective surface at a specific dihedral angle, the ejected material is redirected along the protective surface and away from the sheet, transforming the harmful ejection into a controlled flow that prevents contamination
2Ease of operation
If build-up is reduced to prevent stacking issues, then sheet handling is improved, but the laser ablation process becomes less effective at removing precoating material
Solution Approach 1:
The protective surface acts as a mediator that decouples the laser ablation process from the build-up formation problem. It allows the laser to effectively remove precoating material while the protective surface manages the ejected material flow, ensuring both effective removal and clean sheet surfaces for stacking
3Measurement precision
If build-up is eliminated to improve weld tracking accuracy, then weld quality is enhanced, but the laser ablation process generates more ejected material
Solution Approach 1:
The ejected precoating material, instead of forming harmful build-up, is redirected by the protective surface to form a controlled flow pattern. The material is carried away by gas flow in a controlled manner, converting the harmful ejection into a beneficial removal mechanism that maintains clean surfaces for accurate weld tracking
4Shape
If a protective surface is introduced to redirect ejected material, then build-up is prevented, but the device complexity increases
Solution Approach 1:
The protective surface is positioned only in the specific local area where build-up occurs - at the edge of the laser removal zone. This localized approach prevents build-up formation without requiring protective surfaces throughout the entire installation, thereby limiting the increase in device complexity to only the necessary local area
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
The method effectively reduces the build-up volume to non-protruding dimensions, ensuring flat sheet stacking, preventing material introduction into the weld, and improving weld tracking accuracy, thereby enhancing the quality of welded parts.
Implementation Method 1
removing through laser ablation at least a portion of the precoating on said at least one face of the precoated sheet in a removal zone
Implementation Method 2
the coating is molten and vapourized and flows radially from the laser beam's central axis
Implementation Method 3
a gas jet to carry and ablate the material
Implementation Method 4
A method using a protective surface with a dihedral angle to redirect ejected precoating material away from the sheet
Implementation Method 5
an aspiration nozzle to remove any remaining material
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Method for preparing a precoated sheet (1) comprising: - providing a precoated sheet (1) comprising a metallic substrate provided with a precoating on at least one of its faces; - removing through laser ablation at least a portion of the precoating on said at least one face of the precoated sheet (1) in a removal zone (6), said ablation step being carried out in an installation (20). The installation (20) comprises at least one protective element (26) comprising a protective surface (28). During the ablation step, the protective surface (28) contacts the precoated sheet (1) in a contact area in register with the laser beam (22) as the laser beam (22) removes the portion of the precoating. A plane tangent to said protective surface (28) at the contact area forms a dihedral angle with the plane of the face (12) of the precoated sheet (1), this angle being strictly smaller than 90°.