Laser Cutting Burn Detection via Reflected Beam Variability
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Solution Overview
Problem
Conventional laser processing state determination devices cannot detect burning defects, which occur when cutting thick plates with oxygen assist gas, leading to deteriorated cut surface quality.
Innovation Solution
A laser processing machine and method that includes a laser oscillator, processing head, assist gas supply, reflected beam detector, and a standard deviation calculation unit to determine burning defects by comparing calculated standard deviation values of reflected beam detection values with threshold values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional reflected beam detection with threshold comparison is used, then gouging defects can be detected, but burning defects cannot be detected
Solution Approach 1:
The invention changes the detection parameter from simple threshold comparison to standard deviation calculation. By calculating the standard deviation of reflected beam detection values over time, the system can detect burning defects which cause abnormal fluctuations in the reflected beam signal, while conventional threshold methods only detect gouging defects.
2Measurement precision
If standard deviation calculation is implemented, then burning defects can be detected, but device complexity increases
Solution Approach 1:
The invention replaces complex mechanical or optical modification systems with a computational approach. The standard deviation calculation is performed by a control unit using software algorithms, substituting potential mechanical complexity with simpler computational processing of the existing reflected beam detection signal.
3Measurement precision
If monitoring wavelength selection is used, then detection accuracy improves, but information processing complexity increases
Solution Approach 1:
The invention extracts only the necessary monitoring wavelength information from the reflected beam spectrum. By selecting specific monitoring wavelengths that are most sensitive to burning defects and extracting only those wavelength components for standard deviation calculation, the system reduces information processing complexity while maintaining high detection accuracy.
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
Enables the detection of burning defects, ensuring the quality of cut surfaces during laser cutting of thick plates, thereby preventing excessive melting and improving processing outcomes.
Implementation Method 1
a reflected beam detector configured to detect a reflected beam reflected from the sheet metal when the sheet metal is irradiated with the laser beam
Implementation Method 2
a standard deviation value calculation unit configured to calculate, in a predetermined calculation cycle, a standard deviation value of a reflected beam detection value at a monitoring wavelength from among reflected beam detection values in a predetermined wavelength band
Implementation Method 3
a quality determination unit configured to determine whether or not a burning defect has occurred in which a cut surface of the sheet metal is excessively melted based on a comparison result of comparing, with a first threshold value, the standard deviation value
Data Source
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AI summary
A reflected beam detector (30) detects a reflected beam reflected from a sheet metal (W) when the sheet metal (W) is irradiated with a laser beam so that the sheet metal (W) is cut. A processing state determination unit (40) is provided with a standard deviation value calculation unit and a quality determination unit. The standard deviation value calculation unit calculates, in a predetermined calculation cycle, a standard deviation value of a reflected beam detection value at a monitoring wavelength from among reflected beam detection values in a predetermined wavelength band output from the reflected beam detector (30). The quality determination unit determines whether or not a burning defect has occurred in which a cut surface of the sheet metal (W) is excessively melted based on a comparison result of comparing, with a first threshold value, the standard deviation value calculated by the standard deviation value calculation unit.