Laser Flame Cutting with Deep Focus for Thick Plate Speed
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Solution Overview
Problem
Existing methods for flame cutting thick workpieces with high laser power (>10 kW) fail to achieve a corresponding increase in cutting speed while maintaining high quality and process reliability.
Innovation Solution
Adjusting the focus position of the laser beam to be deeper within the workpiece, with a distance greater than half the workpiece thickness, and increasing the distance between the cutting gas nozzle and the workpiece surface to at least 2 mm, allows for a significant increase in cutting speed with improved power density and cutting gap width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the focus position is located on the top of the workpiece or slightly below/above the surface (conventional method), then the power density at the workpiece surface is high, but the cutting speed increases less than proportionally with laser power increase
Solution Approach 1:
The patent inverts the conventional focusing approach by moving the focus position from the workpiece surface or near-surface region to a depth greater than half the workpiece thickness. This inversion causes the laser beam to be defocused at the surface, reducing power density there, while concentrating energy deeper within the material where it is most needed for cutting thick workpieces, thereby achieving proportional increases in cutting speed with laser power.
Solution Approach 2:
The patent changes the focus position parameter from conventional values (0 to ±5 mm from surface) to a new range (> D/2, where D is workpiece thickness). This parameter change fundamentally alters the beam geometry at the workpiece interface, transforming the cutting mechanism to enable linear scaling of cutting speed with laser power in the 10-20 kW range.
2Productivity
If the focus position is located deep within the workpiece (> half thickness), then the cutting speed increases proportionally with laser power, but the power density at the workpiece surface is reduced
Solution Approach 1:
The patent applies local quality by creating different power density conditions at different locations: the workpiece surface experiences reduced power density (defocused beam) while the interior region at depth > D/2 receives concentrated energy (focused beam). This spatial variation in energy distribution optimizes both surface integrity and cutting efficiency throughout the material thickness.
3Productivity
If the distance between the cutting gas nozzle and the workpiece surface is small (1-2 mm as per conventional standards), then the process control is precise, but the cutting speed increase is limited
Solution Approach 1:
The patent changes the nozzle-to-workpiece distance parameter from the conventional 1-2 mm range to at least 2 mm (preferably at least 3 mm or 5 mm). This parameter change, combined with the deep focus positioning, creates optimal conditions for the defocused beam geometry and gas-assisted material ejection, enabling proportional scaling of cutting speed with laser power while maintaining edge quality.
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 enables a 50% increase in cutting speed with a 50% increase in laser power, while maintaining good cutting edge quality and process reliability, contrasting with previous methods that achieved less than 20% feed increase with similar power increases.
Implementation Method 1
using a laser beam with a power output of more than 10 kW
Implementation Method 2
the laser beam is moved along a cutting direction relative to the workpiece, whereby a kerf forms
Implementation Method 3
flame cutting a workpiece with a thickness of at least 10 mm using a laser beam with a power output of more than 10 kW and oxygen as the cutting gas
Implementation Method 4
liquefied workpiece material and/or slag produced during cutting
Implementation Method 5
a focus position in the direction of the laser beam is located or positioned in the workpiece at a depth greater than half the thickness of the workpiece
Implementation Method 6
the laser beam exits together with the cutting gas from a nozzle opening of a cutting gas nozzle
Implementation Method 7
a distance of a workpiece-side nozzle end face from the workpiece surface is at least 2 mm
Data Source
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AI summary
The invention relates to a method for flame cutting, by means of a laser beam (3) having a power of more than 10 kW and using oxygen as the cutting gas, an in particular planar workpiece (2) having a thickness (D) of at least 10 mm. According to the invention, a focal position (F) is located in the workpiece (2) at a depth that is greater than half (D/2) of the thickness (D) of the workpiece (2) in the beam direction (6) of the laser beam (3), and the laser beam (3) exits, together with the cutting gas, from a nozzle opening (5) of a cutting-gas nozzle (1), wherein a distance (A) of a workpiece-side nozzle end face (8) from the workpiece surface (9) is at least 2 mm, preferably at least 3 mm, particularly preferably at least 5 mm.