Inclined Laser Pre-coating Removal for Welded Joint Quality
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Solution Overview
Problem
Existing processes for welding pre-coated sheets often result in unsatisfactory mechanical properties due to excessive pre-coating ablation, leading to reduced hardness and tensile strength in the welded joint, as well as inadequate corrosion protection.
Innovation Solution
A process involving the partial removal of the pre-coating layer using a laser beam, with a specific inclination angle between 12° and 50°, to minimize pre-coating in the molten zone while retaining an intermetallic alloy layer for corrosion protection, thereby optimizing mechanical and corrosion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a perpendicular laser beam is used for pre-coating removal, then the removal process is simple to implement, but the processing speed is low and pre-coating removal time is excessive
Solution Approach 1:
The patent changes the orientation parameter of the laser beam from perpendicular (0°) to inclined (12°-50°) relative to the sheet surface. This parameter modification enables faster processing speeds while maintaining effective pre-coating removal, directly resolving the contradiction between productivity and device complexity.
2Productivity
If the laser beam is inclined at a large angle to increase processing speed, then productivity improves, but the reflected beam may strike the laser optics causing damage
Solution Approach 1:
The patent applies a moderate inclination angle (12°-50°) that is sufficient to achieve high processing speeds but not excessive enough to cause reflected beam damage to optics. This partial action approach optimizes the balance between productivity improvement and harm prevention.
3Reliability
If the pre-coating layer is completely removed to improve weldability, then welding quality improves, but corrosion protection is lost in the welded area
Solution Approach 1:
The patent applies local quality by selectively removing pre-coating only in the immediate weld zone while preserving it in adjacent areas. This creates different pre-coating conditions in different locations: removed where welding occurs (improving weld quality) and retained where corrosion protection is needed (maintaining corrosion resistance).
Solution Approach 2:
Instead of completely removing the pre-coating layer across the entire sheet, the patent applies partial removal only in the specific weld area. This partial action achieves the necessary weldability improvement without excessive removal that would compromise corrosion protection in non-welded regions.
4Manufacturing precision
If the laser beam moves slowly to ensure complete pre-coating removal, then removal completeness improves, but processing time increases
Solution Approach 1:
The patent changes the laser beam orientation parameter to inclined position, which fundamentally alters the interaction dynamics between laser and pre-coating. This parameter change enables high-speed processing while maintaining complete removal effectiveness, resolving the time-quality contradiction.
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 reduces pre-coating ablation time, enhances mechanical properties of the weld, and ensures sufficient corrosion resistance around the welded joint by maintaining a thin layer of intermetallic alloy, thus improving the efficiency and quality of the welding process.
Implementation Method 1
the removal being carried out by means of the impact of a Laser beam on said pre-coating layer
Data Source
Figure 1~2
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Figure 5~6
AI summary
The invention relates to a method for producing a pre-coated metal sheet for the welding thereof to another pre-coated metal sheet, said method comprising successive steps according to which: a pre-coated metal sheet (1) is supplied, comprising a metal substrate (3) provided with a pre-coating layer on at least one of the faces (10) thereof, then at least part of said pre-coating layer (5) is removed from at least one face (10) of said pre-coated metal sheet (1) so as to form a removal area (7), said removal being carried out by means of the impact of a laser beam (15) on said pre-coating layer (5), the removal step comprising, throughout the removal, the relative movement of said laser beam (15) in relation to the metal sheet (1) in a direction of advancement (A). During the removal, the laser beam (15) is inclined in relation to the face (10) of the metal sheet (1) such that the orthogonal projection of the laser beam (15) on said face (10) of the sheet metal (1) is located in the region of the metal sheet (1) in which the removal has already been carried out, and the laser beam forms an angle of inclination (a) of between 12° and 50° with the direction normal (N) to the surface of the metal sheet (1).