Laser Welding Seam Tracking Sensor Calibration
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Solution Overview
Problem
Current laser welding processes face challenges in achieving precise seam position control, especially with compensation for drift movements of the laser beam in the processing optics, leading to inaccuracies in weld seam formation, particularly when welding different materials like steel and cast iron.
Innovation Solution
A method involving the detection of the joint position in multiple measuring areas using a sensor device, such as a CMOS camera, to adjust the laser processing head's position and coordinate system, allowing for precise alignment and compensation of drift movements by generating test points and shifting measurement areas to ensure accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a seam tracking sensor is manually adjusted using low-power laser beam to generate test points, then the sensor can be calibrated to detect joint position, but beam offset occurs during high-power welding and the process is time-consuming
Solution Approach 1:
The patent performs preliminary calibration by detecting the joint position with the sensor at multiple positions along the joint path before actual welding begins. The system pre-determines correction values for sensor offset and beam drift based on these preliminary measurements, so that when high-power welding starts, the corrections are already applied and the weld seam position accuracy is maintained without time-consuming adjustments during the welding process.
2Measurement precision
If conventional seam tracking sensors are used to detect joint position in advance of the laser beam, then tolerances in workpiece and clamping device can be compensated, but lateral displacements caused by workpiece torsion and laser beam drift cannot be detected
Solution Approach 1:
The patent divides the measurement task into multiple segments by placing sensors at different positions: one sensor detects joint position in advance of the laser beam, while additional sensors detect joint position at and behind the laser beam position. This segmentation allows the system to separately measure and compensate for different types of errors including lateral displacements caused by workpiece torsion and laser beam drift, thereby improving reliability without sacrificing measurement precision.
3Measurement precision
If multiple independent sensors are used to detect joint position and compensate for workpiece torsion, then accuracy can be improved, but the use of multiple sensors with positional tolerance reduces the overall accuracy
Solution Approach 1:
The patent merges multiple measurement functions into a single integrated sensor system. Instead of using multiple independent sensors that would have relative positional tolerances, the invention uses one sensor to perform multiple detection tasks at different positions along the joint path. The sensor captures images at multiple locations and the evaluation device processes all this information together to determine joint position and calculate corrections, thereby achieving high accuracy while reducing device complexity.
4Ease of manufacture
If manual calibration methods are used for seam tracking sensors, then the process is simple to implement, but the accuracy depends on operator skill and available measuring equipment
Solution Approach 1:
The patent implements a self-calibrating system where the sensor and evaluation device automatically determine the joint position and calculate correction values without requiring manual intervention. The system performs its own calibration by detecting the joint at multiple positions, computing the offset between sensor-detected position and actual joint position, and storing correction values in memory. This self-service approach eliminates dependence on operator skill and available measuring equipment while maintaining ease of implementation through automated procedures.
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 ensures highly precise seam position control and compensates for drift movements, resulting in improved accuracy and quality of the weld seam, even with robotic guidance, by adapting the sensor coordinate system to the workpiece geometry and correcting path errors.
Implementation Method 1
detecting the position of a joint in a first measuring area in front of a laser beam position on the workpiece, detecting the laser beam position in a second measuring area
Data Source
Figure 1~3b
Figure 4a~6
Figure 7a~8
AI summary
Setting-up method for laser welding comprises: (A) using a sensor system to determine the position of the joint (19) on a workpiece in a first measurement zone (17a) ahead of the beam position (18); (B) then measuring it in a second zone (17b) overlapping the beam position and/or a third zone (17c) after the beam position; (C) comparing the position of the joint in the zones and the beam position; and (D) adjusting the position, orientation and coordinate system of the sensor system and/or laser head relative to the workpiece. An independent claim is included for a laser welding method incorporating the setting-up method.