Composite Laser Beam Cutting for Thick-Metal Kerf Control
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Solution Overview
Problem
Laser cutting of metal workpieces, especially thick materials, faces challenges with irregular cut surfaces and self-burning due to high-power cutting methods, which affect kerf control and quality, particularly when using one-micrometer waveband laser beams with oxygen assist gas.
Innovation Solution
A laser processing apparatus and method utilizing a composite laser beam formed by combining a circular and annular laser beam within a multi-core optical fiber, with a control unit to adapt power density in response to workpiece thickness and cutting direction changes, optimizing beam profiles for varying material thicknesses and cutting operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-power laser beam is used to cut thick materials, then cutting capability is improved, but cut surface irregularities and self-burning occur
Solution Approach 1:
The laser beam is segmented into multiple independent cores within a multi-core optical fiber, with at least one central core and at least two peripheral cores. Each core can be independently controlled to deliver specific power levels, allowing the total power to be distributed in a controlled manner that prevents localized overheating and self-burning while maintaining high cutting capability.
Solution Approach 2:
Different regions of the laser beam are assigned different power densities through the multi-core fiber configuration. The peripheral cores can be controlled to provide lower power density at the edges while the central core provides higher power density in the center, creating a optimized power distribution profile that prevents edge melting and self-burning while maintaining effective cutting through the material.
2Use of energy by moving object
If one-micrometer waveband laser beam with oxygen assist gas is used, then energy density is improved, but melt width widens and kerf control deteriorates
Solution Approach 1:
The multi-core optical fiber enables different power densities to be delivered to different regions of the cut. By controlling the power in peripheral cores versus central cores, the system creates a power distribution that concentrates energy where needed for cutting while reducing energy at the edges, thereby preventing excessive melt width and improving kerf control.
Solution Approach 2:
The system changes the spatial distribution parameter of the laser beam by using multiple cores with different power levels instead of a single uniform beam. This parameter change allows the same total power to be delivered with a modified intensity profile that prevents edge melting and improves cut quality.
3Device complexity
If single beam profile is used, then device complexity is reduced, but adaptability to different material thicknesses deteriorates
Solution Approach 1:
The multi-core optical fiber system provides multiple functions within a single device configuration. The same fiber assembly can deliver different power distributions by independently controlling different cores, enabling adaptation to various material thicknesses and cutting requirements without changing the physical beam delivery system, thus achieving universality while maintaining relatively simple device 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 adjusting power densities of center and ring beams, achieving better control over cutting surfaces and processing speed, reducing irregularities and self-burning, and enabling efficient cutting of both thin and thick materials with enhanced precision and cleanliness.
Implementation Method 1
combining means connected to said first and second feed fibers and to a multi-core optical fiber, the combining means being adapted to form a composite laser beam by having said at least one first optical feed fiber aligned with a first core of said multi-core optical fiber, and said at least one second optical feed fiber aligned with at least one second core of said multi-core optical fiber
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
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
Data Source
Figure 1a~1d
Figure 2~3
Figure 4~5
AI summary
The invention concerns an apparatus and its use for laser processing. The invention also concerns a method. According to the invention, at a first laser device (30), providing a first optical feed fiber (32) and at a second laser device (31 ) providing a second optical feed fiber (33). A beam combining means (34) connected to the first and second feed fibers and to a multi-core optical fiber (35) is adapted to form a composite laser beam by having the first optical feed fiber (32) 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 (35). The first and second cores output a composite laser beam (2) to a workpiece (21) to be processed. A control unit (10) 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 (22) 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 (21) being cut.