Laser Beam Focal Position Control Using Cut Gap Width Imaging
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Solution Overview
Problem
Determining the focal position of a processing beam, such as a laser beam, is challenging due to the difficulty in directly measuring it and the influence of disturbance variables, making it difficult to maintain a consistent cutting process.
Innovation Solution
A method and apparatus that determine the focal position by recording spatially resolved images of the workpiece's cut edges to measure the cutting gap width, using caustic characteristics of the beam to ascertain the focal position, and adjust it as needed during the cutting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct measurement of focal position is attempted, then measurement precision may be improved, but measurement becomes infeasible due to difficulty and disturbance variables
Solution Approach 1:
The patent uses the cutting gap width as an intermediary parameter to indirectly determine the focal position. Instead of directly measuring the focal position which is difficult and prone to disturbances, the method measures the cutting gap width (which is easier to measure using imaging cameras) and uses this as a mediator to infer the focal position through established relationships between gap width and focal position.
Solution Approach 2:
The patent replaces direct mechanical/optical measurement of focal position with an imaging-based measurement system. Using imaging cameras to capture cut edges and calculate gap width substitutes the difficult direct focal position measurement with a more feasible optical imaging and image processing approach.
2Stability of the object's composition
If focal position is kept constant by regulating influencing parameters, then process stability is improved, but adaptability to changing conditions deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the cutting gap width is continuously monitored during processing, and this information is used to adjust the focal position in real-time. The system measures the actual gap width, compares it to reference values, and regulates the focal position accordingly, enabling the process to adapt to changing conditions while maintaining stability.
Solution Approach 2:
The patent transitions from a static focal position regulation approach to a dynamic one. The focal position is no longer kept constant but is continuously adjusted based on real-time measurements of the cutting gap width, allowing the system to adapt dynamically to changing processing conditions while maintaining process stability.
3Measurement precision
If offline determination methods are used, then measurement accuracy may be improved, but productivity deteriorates due to time loss
Solution Approach 1:
The patent performs preliminary characterization of the relationship between cutting gap width and focal position during offline setup or initial calibration. This preliminary action creates reference data that enables rapid online determination of focal position during actual processing, combining the accuracy benefits of offline methods with the speed needed for production.
Solution Approach 2:
The patent creates a reference model or lookup table during offline operations that copies the relationship between gap width and focal position. This reference data is then used during online processing to quickly determine focal position without performing complex offline analysis each time, thus maintaining accuracy while improving productivity.
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 accurate and online determination and regulation of the focal position, eliminating the need for offline methods, improving measurement accuracy, and ensuring a robust cutting process.
Implementation Method 1
recording at least one spatially resolved image of an area of the workpiece that is to be monitored and comprises the cut edges of a cutting gap
Data Source
AI summary
The invention relates to a method for determining a focal position of a machining beam, in particular a laser beam, relative to a workpiece when machining the workpiece using the machining beam, having the following steps: receiving at least one spatially resolved image of a workpiece region to be monitored, said region comprising the cut edges of a cut gap formed during the machining process on the upper face of the workpiece, ascertaining a gap width of the cut gap on the upper face of the workpiece using the cut edges in the at least one spatially resolved image, and determining the focal position of the machining beam relative to the workpiece using the ascertained gap width. The invention also relates to a corresponding device.