Beam Shaper Wavefront Layout for Smooth Thick-Sheet Laser Cutting
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Solution Overview
Problem
Laser cutting of thick metal sheets often results in corrugated surfaces due to hot spots, turbulences, and uncontrolled reaction fronts, leading to reduced cutting quality, especially for workpieces thicker than 15 mm.
Innovation Solution
A beam shaper that includes a first beam shaping section for shaping the central part of the laser beam with spherical wave fronts and a second section for shaping the peripheral part with parallel wave fronts, allowing for incoherent superposition to achieve a homogeneous intensity distribution, stabilizing the cutting process and reducing surface corrugations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional laser beam cutting is used on thick metal sheets, then cutting capability is achieved, but surface corrugations and hot spots are formed reducing cutting quality
Solution Approach 1:
The patent applies local quality by creating different intensity zones within the laser beam profile. The beam shaper generates a customized intensity distribution with a central low-intensity zone and peripheral high-intensity zones, allowing different regions of the beam to perform different functions: the periphery creates ignition points while the center avoids excessive heating that causes hot spots
Solution Approach 2:
The patent changes the intensity distribution parameter of the laser beam from a conventional Gaussian profile to a customized profile with multiple intensity levels. This parameter change is achieved through optical beam shaping elements that transform the beam's spatial intensity distribution to control heating patterns and eliminate surface corrugations
2Length of moving object
If high laser power is used to cut thick workpieces, then cutting depth is achieved, but uncontrolled reaction front growth occurs
Solution Approach 1:
The patent segments the laser beam intensity into multiple zones with different intensity levels. The beam shaper creates a segmented intensity profile where the periphery has high intensity for ignition and the center has low intensity for controlled heating, preventing uncontrolled reaction front propagation while maintaining cutting depth
Solution Approach 2:
The patent implements feedback control by using sensors to detect the reaction front position and adjusting the laser beam intensity distribution accordingly. The beam shaper dynamically modifies the intensity profile based on real-time feedback to maintain stable reaction front growth at the desired cutting depth
3Temperature
If conventional Gaussian beam profile is used, then laser beam delivery is simple, but homogeneous heat distribution is not achieved
Solution Approach 1:
The patent introduces a beam shaper as an intermediary optical element between the laser source and the workpiece. This intermediary device transforms the conventional Gaussian beam profile into a customized intensity distribution, achieving homogeneous heat distribution while managing the added system complexity through integrated optical design
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
The beam shaper produces a laser beam with a substantially homogeneous intensity distribution perpendicular to its direction, resulting in smooth cut surfaces with reduced corrugation amplitudes, even for thick metal sheets, by effectively managing heat input and ignition dynamics during the cutting process.
Implementation Method 1
a first beam shaping section (2) for shaping a central part of the laser beam such that the laser beam includes first wave fronts (85) which are at least partially spherical, and a second beam shaping section (3) for shaping a peripheral part of the laser beam such that the laser beam includes second wave fronts (84) which are at least partially parallel
Implementation Method 2
the second wave fronts (84) at least partially incoherently superimpose the first wave fronts (85)
Implementation Method 3
a part of the workpiece surface is heated until ignition temperature is reached and the reaction of the metal and oxygen gas is started
Implementation Method 4
the reaction between the oxygen and the metal actually creates additional energy in the form of heat, which supports the cutting process
Implementation Method 5
The molten liquid metal, which has very low viscosity, is removed from the cut by the shear force of the oxygen jet
Implementation Method 6
the material is molten solely by the laser power and blown out of the cut kerf by the kinetic energy of the gas jet
Data Source
Figure 1~2
Figure 3a~3b
Figure 3c~3d
AI summary
A beam shaper (1) for shaping a laser beam is provided, including a first beam shaping section (2) designed for shaping a central part of the laser beam, and a second beam shaping section (3) designed for shaping a peripheral part of the laser beam. Moreover, a device for laser beam treatment of a workpiece and a method for laser beam treatment of a workpiece are provided.