Multi-Core Optical Fiber Beam Shaping for Laser Cutting and Welding
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Solution Overview
Problem
Laser welding and cutting techniques face issues such as excessive heat leading to hardening and deformation in weld seams, irregular cut surfaces, and the need for high-power lasers to manage thick materials, which are not efficiently addressed by existing methods.
Innovation Solution
Combining keyhole laser cutting/welding with heat conduction welding using a dual-core optical fiber setup, where a high-brightness fiber laser and a lower-brightness diode laser are aligned within a dual-core optical fiber to produce a hybrid laser beam with adjustable intensity profiles, allowing for both efficient cutting and welding with reduced hardening effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-power laser beam is used for keyhole welding to join thick materials, then welding depth and strength are improved, but excessive heat causes hardening and deformation of the weld seam
Solution Approach 1:
The laser beam is segmented into multiple modes (fundamental Gaussian mode and higher-order modes) that can be independently controlled. This allows separation of the heating function (using higher-order modes for broader heat distribution) from the keyhole formation function (using fundamental mode for concentrated energy), thereby reducing excessive localized heat while maintaining weld penetration and strength
Solution Approach 2:
The invention enables dynamic adjustment of the laser beam intensity profile by controlling the relative power distribution between different laser modes. This dynamic control allows optimization of the intensity distribution to match the specific welding requirements, preventing excessive heat input that causes hardening and deformation while maintaining adequate penetration
2Productivity
If high-intensity laser beam is focused to a small spot to increase energy density, then cutting speed and penetration are improved, but the focal spot becomes too narrow to effectively vaporize and remove molten metal from thick materials
Solution Approach 1:
The laser beam is divided into multiple mode components with different spatial intensity distributions. The fundamental mode provides a concentrated central peak for deep penetration and high cutting speed, while higher-order modes provide broader energy distribution that expands the effective focal spot area, enabling simultaneous achievement of high cutting speed and adequate molten metal removal
Solution Approach 2:
Different regions of the laser beam cross-section are assigned different intensity characteristics through mode composition. The center region maintains high intensity for penetration and speed, while the peripheral regions have extended intensity distribution to broaden the focal spot area, creating a composite beam with non-uniform but optimized local quality for thick material cutting
3Device complexity
If a single laser beam with fixed intensity profile is used, then device complexity is reduced, but the laser cannot efficiently perform both cutting and welding operations
Solution Approach 1:
The laser system incorporates dynamic control of beam intensity profile through adjustment of mode power ratios. A single laser source can adapt its output characteristics in real-time to match different processing requirements (cutting vs. welding), providing versatility without requiring multiple separate laser systems, thus maintaining relatively simple device architecture
Solution Approach 2:
The single laser beam is designed to perform multiple functions (both cutting and welding) by dynamically adjusting its intensity profile. The same laser source can be configured for keyhole welding, conduction welding, or cutting operations depending on the desired outcome, eliminating the need for separate specialized laser systems while maintaining operational versatility
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 reduced hardening and deformation in weld seams, cleaner cut surfaces, improved control over the cutting process, and the ability to use a single laser source for both cutting and welding, while reducing costs.
Implementation Method 1
a first optical feed fiber adapted to carry a first laser beam from a first laser device to a first core of the multi-core optical fiber, and a second optical feed fiber adapted to carry a second laser beam from a second laser device to the second core of the 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 of 1500 degrees or over so that the workpiece melts
Implementation Method 3
an assist gas may be fed to prevent corrosion of the molten metal
Data Source
Figure 1~2
Figure 3~6
Figure 7
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(6), providing a first optical feed fiber (8) and a second laser device (7) providing a second optical feed fiber (9) is provided. A beam combining means (11) connected to the first and second feed fibers and to a multi-core optical fiber (12) is adapted to form a composite laser beam by having the first optical feed fiber (8) 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 (12). The first and second cores outputs a composite laser beam (16) to a workpiece (14) to be processed. A control unit (10) individually controls the power density of the output laser beams.