Pulsed Laser Cutting for Thick Metal Kerf Quality
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Solution Overview
Problem
Existing laser cutting methods for thick metal workpieces, especially those with fine structures and corners, suffer from reduced quality of the kerf, including increased burr formation and heat-affected zones, when using high laser powers.
Innovation Solution
A laser cutting method using a pulsed laser beam with long pulses and a quasi-continuous wave mode, combined with a non-reactive gas, to cool the workpiece during intervals, reducing heat affected zones and improving kerf quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high laser powers are applied to increase cutting speed and enable cutting of thicker workpieces, then cutting speed and thickness capability are improved, but the quality of the kerf suffers with increased burr formation and heat-affected zones
Solution Approach 1:
The patent applies periodic pulsed laser irradiation instead of continuous wave irradiation. The laser operates in pulsed mode with pulse widths of 100-1000 μs and duty cycles of 1-50%, creating periodic heating and cooling cycles that prevent excessive heat accumulation and burr formation while maintaining effective cutting speeds for thick workpieces
Solution Approach 2:
The patent dynamically adjusts laser parameters including pulse width (100-1000 μs), pulse frequency (10-1000 Hz), and duty cycle (1-50%) based on workpiece thickness and material properties. This dynamic parameter optimization allows the system to adapt to different cutting conditions, maintaining kerf quality across varying productivity requirements
2Strength
If high laser powers are applied for thick workpieces, then cutting capability is improved, but heat-affected zones increase causing quality degradation
Solution Approach 1:
The periodic pulsed laser operation creates intervals of laser off-time between pulses, allowing heat to dissipate from the workpiece during the off-periods. This prevents thermal accumulation and minimizes heat-affected zones while maintaining sufficient peak power during pulse periods to cut through thick workpieces effectively
Solution Approach 2:
The patent changes the temporal parameters of laser energy delivery by using pulsed operation with specific pulse widths (100-1000 μs) and duty cycles (1-50%). This parameter transformation converts continuous high-power irradiation into controlled intermittent irradiation, reducing thermal damage while preserving cutting capability
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 method enhances kerf quality by reducing burr formation and smoothing the cutting face, while maintaining effective cutting speeds for thick workpieces.
Implementation Method 1
a laser beam emitted by a laser cutting head is caused to impinge on the workpiece... a directed laser beam moves relative to the metal workpiece to locally create a cut in the metal material at the position of incidence of the laser beam
Implementation Method 2
Modern laser cutting machines also direct a gas jet onto the position of incidence of the laser beam... The gas jet may assist the removal ('blowing') of molten metal material
Implementation Method 3
A laser cutting method using a pulsed laser beam with long pulses and a quasi-continuous wave mode, combined with a non-reactive gas, to cool the workpiece during intervals, reducing heat affected zones
Data Source
Figure 1~2
Figure 3~6
AI summary
A laser fusion cutting method for cutting a metal workpiece with a high power laser, the laser having an output power of at least 10 kW or at least 15 kW, may benefit if the laser is operated in pulsed operation, with long laser pulses having a pulse width of at least 10 µs.