Donut Keyhole Laser Cutting for Thick Plate Oxy-Cutting
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Solution Overview
Problem
Current laser cutting technologies are limited in maximum thickness capability and are inefficient compared to other thermal cutting methods like oxy-fuel cutting, with increased costs and challenges in piercing and spatter projections, especially when trying to cut thicker materials.
Innovation Solution
A method that focuses a laser beam into a tiny spot with high power density above the keyhole mode threshold, oscillating in a periodic loop pattern to heat the workpiece above 900°C, enabling oxy-cutting with an oxygen stream, and using a long focal length to protect optics and enhance cutting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If laser power is increased to cut thicker materials, then cutting thickness capability is improved, but cost and system complexity increase significantly
Solution Approach 1:
The patent applies dynamics by oscillating the laser beam in a periodic loop pattern rather than using a static high-power beam. This dynamic approach allows a lower power laser (1-12kW) to effectively cut thicker materials by continuously moving the keyhole position, preventing heat accumulation and enabling deeper penetration through repeated heating cycles on the same path.
Solution Approach 2:
The patent employs periodic action through the oscillating laser beam that follows a periodic loop pattern. The beam repeatedly traverses the same path, creating periodic heating cycles that progressively deepen the keyhole through the material thickness. This periodic action enables thick material cutting without requiring proportionally higher laser power.
2Length of moving object
If traditional LASOX process is used to cut thicker materials, then cutting thickness capability is improved, but cutting speed decreases and cost increases
Solution Approach 1:
The patent changes the key parameter from conduction mode heating to keyhole mode heating by increasing power density through beam oscillation. This parameter change enables the laser to penetrate deeper into the material while maintaining higher cutting speeds, as the keyhole mechanism removes molten material more efficiently than conduction mode, directly addressing the speed limitation of LASOX processes.
3Length of moving object
If laser beam is focused into a large spot for oxy-cutting, then cutting thickness capability is improved, but cutting speed decreases due to conduction mode heating
Solution Approach 1:
The patent uses dynamic beam oscillation to maintain a moving keyhole position rather than a static large spot. This dynamic approach allows the laser to continuously advance through the material at high speed while the oscillation pattern ensures adequate heating and keyhole formation at each position, resolving the speed limitation of static large spot oxy-cutting methods.
4Productivity
If high power density is used to create keyhole mode, then cutting speed and penetration are improved, but spatter projections on optics occur
Solution Approach 1:
The patent uses dynamic beam oscillation to prevent spatter accumulation on optics by continuously moving the keyhole position. This prevents molten material from settling in a fixed location and projecting onto the optical path, while still maintaining the high power density needed for fast cutting and deep penetration through the periodic heating cycles.
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 method allows for cutting thicker plates as efficiently as oxy-fuel cutting, with improved cutting speed and quality, and deeper penetration, while avoiding the costs and inefficiencies of traditional LASOX processes.
Implementation Method 1
heating an area of the material to be cut to an enabling temperature range with a laser beam
Implementation Method 2
heating it in conduction mode beyond 900C
Implementation Method 3
the oxy-cutting process is enabled by the exothermic oxidation of the metal which melts away due to an O2 flow
Data Source
Figure 1
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Figure 2b
AI summary
A method of combined laser and oxy-cutting, including heating an area of the material to be cut to an enabling temperature range with a laser beam and introducing an oxygen stream into the heated area, thus cutting the material. Wherein the laser beam is directed in a periodic path.