Laser Welding Beam Steering for Dissimilar Material Joints
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Solution Overview
Problem
Laser welding of materials with different melting points or thicknesses faces challenges in achieving a uniform weld pool due to asymmetrical energy distribution, often requiring trial and error for offsetting laser beam positions and limited by the small spot size of modern lasers, which complicates the application of sufficient energy across the weld junction.
Innovation Solution
The implementation of Pulse Spread Technology, which involves steering a laser beam across the material junction with varying power density profiles, customizing the intensity and speed of the laser beam to ensure equal melting of both materials by applying higher power density to the higher melting point material and lower power density to the lower melting point material, thereby creating a more uniform weld pool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the laser beam is offset from the weld junction to apply more energy to the higher melting point material, then the energy distribution compensates for melting point differences, but the weld pool becomes asymmetrical and weld quality is compromised
Solution Approach 1:
The patent implements dynamic beam steering that adjusts the laser spot position in real-time during each pulse cycle. The beam oscillates between offset positions (applying more energy to higher melting point material) and centered positions (creating symmetrical weld pools) in a controlled sequence, allowing both energy compensation and weld pool symmetry to be achieved
Solution Approach 2:
The system uses periodic beam oscillation at specific frequencies to cycle the laser spot between different positions across the weld junction. This periodic movement allows repeated application of energy compensation offsets while maintaining overall weld pool symmetry through balanced cycling patterns
2Manufacturing precision
If the laser spot is centered on the weld junction to melt equal amounts of each material, then the weld pool symmetry is improved, but the higher melting point material may not receive sufficient energy or the more fragile material may be damaged
Solution Approach 1:
The system dynamically adjusts beam position timing and amplitude based on material properties. During specific phases of the oscillation cycle, the beam offsets toward the higher melting point material to deliver additional energy, while during other phases it centers on the junction to maintain symmetry, with the entire pattern repeatable and controllable
Solution Approach 2:
The patent changes multiple parameters including beam position, oscillation frequency, pulse duration, and power levels to optimize both energy distribution and weld pool symmetry. By adjusting these parameters dynamically, the system adapts to different material combinations and thicknesses
3Measurement precision
If a highly focused laser beam is used to reduce spot size, then the laser precision and energy concentration are improved, but the inherent gaps between materials become more significant and sufficient energy application becomes nearly impossible
Solution Approach 1:
The patent transitions from static single-point heating to two-dimensional beam oscillation across the weld junction. By moving the focused beam back and forth in a controlled pattern, the system distributes the concentrated energy across a wider effective area, bridging material gaps while maintaining the precision benefits of focused beams
Solution Approach 2:
The system employs dynamic beam steering to move the focused laser spot rapidly between positions on either side of the weld junction. This dynamic movement allows the highly focused beam to deliver sufficient total energy by cycling through multiple locations, effectively treating the gap between materials through temporal rather than spatial distribution
4Use of energy by moving object
If the zig zag beam pattern is offset to apply energy over a wider area of each material, then the energy distribution across materials is improved, but the weld pool becomes asymmetrical due to dissimilar amounts of each material being melted
Solution Approach 1:
The patent intentionally introduces asymmetry in the form of an offset zig-zag pattern that applies more energy to the higher melting point material, while simultaneously using dynamic control to balance the overall energy distribution. The asymmetrical offset is compensated by adjusting beam dwell times and oscillation amplitudes to maintain weld pool symmetry
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 results in a significantly reduced weld time and improved weld quality by ensuring equal amounts of each material are melted, reducing the risk of damaging the more fragile material and enhancing the symmetry of the weld pool.
Implementation Method 1
a fiber laser configured to generate a laser beam according to the one or more varying intensity profiles
Implementation Method 2
the power density that is applied varies in a predetermined fashion based on the beam's position on the part
Implementation Method 3
beam steering optics for moving the generated laser beam
Implementation Method 4
customizing the intensity and speed of the laser beam to ensure equal melting of both materials
Implementation Method 5
applying higher power density to the higher melting point material and lower power density to the lower melting point material
Data Source
Figure 1~2
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AI summary
A system and method for precision welding using a fiber laser is disclosed in which varying intensity laser pulses are spread across the material junction in a number of high aspect ratio areas. The power density applied along each area is varied to accommodate differences in the material characteristics of each material while allowing for the creation of a more uniform weld pool alloy.