Laser Beam Focus Checking Along 3D Workpiece Trajectories
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Solution Overview
Problem
Existing methods for checking the focus position of a laser beam during welding processes are often inaccurate and prone to errors, especially when dealing with non-planar workpieces, as they rely on manual adjustments or pilot lights, and fail to account for deviations in focus position along complex geometries.
Innovation Solution
A method that focuses the laser beam at multiple positions along a trajectory on the workpiece, detects radiation at each position, and compares signal values to a reference value formed from multiple signal values to accurately determine and adjust the focus position, using a programmable focusing optical unit to compensate for deviations and maintain a nominal focus position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual checking or pilot light methods are used to check focus position, then the checking process is simple to implement, but the measurement precision is poor and error-prone
Solution Approach 1:
The patent replaces manual mechanical checking methods and simple optical pilot lights with an automated radiation detection system. The control unit automatically detects radiation generated during laser-workpiece interaction, processes the signals, and determines focus position accuracy, eliminating manual intervention while achieving high measurement precision through electronic signal analysis.
Solution Approach 2:
The system implements feedback by detecting radiation signals during laser processing, comparing the detected signal values against reference values, and using this comparison to determine whether the focus position is accurate. This closed-loop feedback mechanism enables automatic focus verification without requiring complex mechanical adjustment devices.
2Reliability
If focus position is checked at only one position, then the checking process is fast and simple, but the reliability is insufficient for complex three-dimensional workpieces
Solution Approach 1:
The patent divides the focus position checking process into multiple discrete measurement positions along the laser trajectory. By checking focus accuracy at multiple segmented positions rather than a single point, the system reliably verifies focus maintenance across complex three-dimensional workpiece geometries while keeping each individual measurement quick and automated.
Solution Approach 2:
The system performs preliminary focus position checks at multiple positions before actual welding processing begins. This preliminary verification ensures that the focusing optical unit maintains accurate focus throughout the entire trajectory, preventing defective welds before they occur and eliminating the need for time-consuming post-processing inspections.
3Adaptability or versatility
If the focusing optical unit is not adjustable, then the device structure is simple, but the adaptability to different workpiece geometries is poor
Solution Approach 1:
The patent employs a dynamically adjustable focusing optical unit that can change its focal position along the laser beam trajectory. This dynamic adjustment capability allows the system to adapt to varying workpiece geometries and maintain optimal focus at different positions, transforming a static optical system into a flexible, geometry-adaptive focusing mechanism.
Solution Approach 2:
The system changes the focal position parameter of the focusing optical unit based on the specific geometry of the workpiece and the laser trajectory. By dynamically adjusting this key optical parameter, the system achieves high adaptability to different workpiece shapes and sizes without requiring completely different optical systems for each application.
4Manufacturing precision
If focus position checking is not performed, then the processing speed is high, but the manufacturing precision of welding spots deteriorates
Solution Approach 1:
The patent implements continuous focus position verification throughout the laser processing operation by automatically detecting radiation signals at multiple positions along the trajectory. This continuous monitoring ensures welding spot quality is maintained without interrupting the processing flow, achieving both high manufacturing precision and sustained productivity through seamless integration of inspection into the manufacturing process.
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 approach allows for precise and flexible checking of the focus position, independent of material and laser parameters, enabling accurate welding even on three-dimensional workpieces by using a relative reference value based on signal values from multiple positions, thereby improving the quality of welding spots and allowing for real-time adjustments during processing.
Implementation Method 1
a laser beam (4) is focused at a plurality of positions along at least one trajectory (B) on a workpiece (2)... detecting radiation (11), which is generated during an interaction of the laser beam (4) with the workpiece (2)
Data Source
AI summary
A method checks a focus position of a laser beam in relation to a workpiece. The method includes: focusing the laser beam at a plurality of positions along a trajectory on the workpiece; detecting radiation generated during an interaction of the laser beam with the workpiece at a respective position of the positions; determining signal values corresponding to the detected radiation at the respective position; and checking the focus position at at least one of the positions by comparing the respective one of the signal values at the respective position with a reference value formed from the signal values.