Composite Laser Beam Control for Thick Metal Cutting Quality
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Solution Overview
Problem
Laser cutting of metals, particularly thick materials, faces challenges with irregular cut surfaces and self-burning due to high-power cutting methods, and the use of one-micrometer waveband laser beams with oxygen assist gas leads to unnecessary melt width and kerf control issues.
Innovation Solution
A laser processing apparatus and method utilizing a composite laser beam formed by combining a circular center beam and an annular ring beam, with a control unit to individually adjust power densities based on workpiece thickness and cutting progression, allowing for adaptive beam profile optimization during cutting operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-power laser beam is used to cut thick materials, then cutting capability is improved, but cut surface irregularity and self-burning occur
Solution Approach 1:
The laser beam is divided into multiple independent cores (e.g., 7 cores) within the optical fiber, allowing each core to carry a portion of the total power. This segmentation enables distributed heating that reduces localized overheating and self-burning while maintaining high total power for cutting thick materials, thereby improving cut surface quality.
Solution Approach 2:
Different cores in the multi-core optical fiber can be assigned different power levels and beam characteristics tailored to specific cutting conditions. This local quality adjustment allows optimization of power distribution across the cut width, preventing both insufficient penetration and excessive overheating that causes surface irregularity.
2Use of energy by moving object
If one-micrometer waveband laser beam with oxygen assist gas is used, then energy intensity and absorbance are improved, but melt width increases and kerf control deteriorates
Solution Approach 1:
The single high-intensity beam is segmented into multiple lower-intensity beams through the multi-core fiber structure. This reduces the peak intensity that causes excessive melting and widening, while the combined effect of multiple beams maintains sufficient total energy for cutting, thereby improving kerf control.
Solution Approach 2:
The invention changes the spatial distribution parameter of the laser beam by using multiple cores with different positions and potentially different power levels. This parameter change allows optimization of the energy distribution pattern to achieve better kerf control while maintaining effective cutting.
3Device complexity
If conventional single-beam profile is used, then device simplicity is maintained, but adaptability to varying material thicknesses is limited
Solution Approach 1:
The multi-core optical fiber system provides multiple beam profiles (different power distributions across cores) that can be selectively activated depending on material thickness and cutting conditions. This multi-functionality allows a single device to adapt to various cutting scenarios without requiring multiple separate laser systems.
Solution Approach 2:
The system enables dynamic adjustment of power distribution among the multiple cores based on real-time cutting conditions and material thickness. This dynamic adaptability allows optimization of beam profile during the cutting process, improving versatility while maintaining a relatively simple fixed fiber structure.
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 improves cutting quality by optimizing beam profiles for varying material thicknesses, reducing self-burning, and maintaining high-quality cut surfaces, even during changes in cutting direction, by dynamically controlling the power density of the center and ring beams.
Implementation Method 1
a laser beam of a one-micrometer waveband from a solid-state laser or fiber laser realizes a very high optical energy intensity and absorbance on a metallic work
Implementation Method 2
the laser beam is typically condensed through a condenser lens into a spot of 100-500 μm to increase energy density and instantaneously heat the workpiece to a metal melting point
Implementation Method 3
at least one first laser device, each providing at least one first optical feed fiber with a first laser beam
Data Source
AI summary
The invention concerns an apparatus and its use for laser processing. The invention also concerns a method and an optical component. According to the invention, at a first laser device, providing a first optical feed fiber and a second laser device providing a second optical feed fiber is provided. A beam combining means connected to the first and second feed fibers and to a multi-core optical fiber is adapted to form a composite laser beam by having the first optical feed fiber aligned with a first core of the multi-core optical fiber and the second optical feed fiber aligned with at least one second core of the multi-core optical fiber. The first and second cores outputs a composite laser beam to a workpiece to be processed. A control unit controls power density of at least one of first and second laser beams of the composite laser beam in at least one of: in response to approaching a change point in direction of cutting progression and to cause change in relation between the power density of the first output laser beam and power density of the second output laser beam in accordance with thickness of the workpiece being cut.