Laser Welding Signal Correction for Scan Position Monitoring
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Solution Overview
Problem
Conventional laser welding monitoring apparatuses face challenges in accurately monitoring the state of processing due to light dispersion in scanning lenses and varying signal intensity caused by changes in the position of the processing point.
Innovation Solution
A laser welding monitoring apparatus that includes an acquisition interface, an arithmetic circuit, and a storage device. The apparatus acquires signals from measurement light, which includes plasma light, heat radiation light, and reflected light, and corrects these signals based on pre-stored variation tendency information to suppress variations in intensity due to changes in the processing point position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a light receiving unit is placed outside the optical system for processing, then the structure is simpler and easier to implement, but light from a region wider than the processing point is received, causing the state of the processing point to be hardly reflected accurately and deteriorating the accuracy of determining the state of processing
Solution Approach 1:
The patent introduces a light receiving unit that is positioned within the optical system, acting as an intermediary element that selectively captures light from the processing point. This light receiving unit works in conjunction with the galvanometer mirror and scan lens to ensure that only light from the specific processing point is received, thereby improving measurement precision while maintaining system feasibility
Solution Approach 2:
The patent places the light receiving unit in a different spatial dimension within the optical path, specifically positioning it to receive light after it has been focused by the scan lens. This dimensional repositioning allows the system to distinguish light from the processing point versus light from surrounding regions, resolving the contradiction between ease of implementation and measurement accuracy
2Measurement precision
If a sensor portion is designed to receive light passing through an optical system for processing including a galvanometer mirror and scan lens, then the processing point can be monitored, but the angle and position of laser light are changed by scanning, causing light from the processing point to be dispersed in the scanning lens and signal intensity to change depending on processing point position
Solution Approach 1:
The patent implements a feedback mechanism where the signal intensity variations caused by scanning are measured and then corrected through arithmetic processing. The system stores variation tendency information that corresponds to how signal intensity changes with processing point position, and uses this feedback to correct the measured signals, thereby maintaining reliable and consistent monitoring results across different scanning positions
Solution Approach 2:
The patent changes the parameter of signal intensity by applying correction based on stored variation tendency information. The arithmetic processing unit adjusts the raw signal intensity values to compensate for scanning-induced variations, transforming the unreliable raw signals into reliable corrected signals that accurately reflect the processing state regardless of position
3Adaptability or versatility
If the position of the processing point is changed by scanning with laser light, then the entire workpiece can be processed, but the intensity of measurement light varies depending on processing point position, making accurate monitoring difficult
Solution Approach 1:
The patent performs preliminary action by storing variation tendency information before actual welding monitoring begins. The system pre-characterizes how signal intensity varies with processing point position by performing scanning without welding, stores this variation pattern, and then uses it to correct subsequent monitoring signals. This preliminary characterization enables accurate monitoring across the entire workpiece area
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 apparatus effectively suppresses the influence of processing point position changes on measurement light intensity, enabling accurate monitoring of the welding state by ensuring consistent signal intensity across different processing positions.
Implementation Method 1
a spectrometer that spectrally disperses the measurement light into the plasma light, the heat radiation light, and the reflected light
Implementation Method 2
irradiating a workpiece with laser light
Implementation Method 3
plasma light generated at the processing point through irradiation with the laser light
Implementation Method 4
heat radiation light
Data Source
AI summary
A laser welding monitoring apparatus includes an acquisition interface that acquires a signal corresponding to measurement light measured by irradiating a workpiece with laser light, an arithmetic circuit that determines the state of processing based on the acquired signal, and a storage device that stores in advance variation tendency information corresponding to a tendency of intensity of the measurement light to vary depending on a position of a processing point in a region scannable with the laser light by using an optical system including a galvanometer mirror and a scan lens on the workpiece. When scanning is performed with the laser light by the optical system in a predetermined welding pattern, and the acquisition interface acquires an intensity signal indicating intensity of the measurement light that has been received, the arithmetic circuit corrects the intensity signal and suppresses a variation in intensity depending on a position of the processing point based on the variation tendency information for each light and determines the state of processing based on the intensity signal that has been corrected.