Laser Cutting Quality Control via Interrupted In-Process Scanning
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Solution Overview
Problem
High-power laser cutting processes face challenges in real-time quality monitoring due to the physical properties of the cutting process, making it difficult to measure quality characteristics directly from process emissions, leading to uncertain online estimation and a lack of effective post-process quality control methods that do not rely on separate test parts or immediate part removal.
Innovation Solution
An offline quality control method that interrupts the cutting process to scan and assess quality features like slag residue, cut edge roughness, and kerf width directly after processing, allowing for immediate identification of defects and adjustment of cutting parameters without requiring part removal, while also integrating temporary online monitoring for adaptive control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If online process control is used to monitor cutting quality in real-time, then immediate quality assessment is possible, but measurement precision is reduced due to inability to directly measure quality characteristics from process emissions
Solution Approach 1:
The cutting process is interrupted after a first partial processing operation to perform offline quality control measurements before the cutting process is fully completed. This preliminary action allows precise measurement of quality characteristics (slag residue, contour sections, cutting gap width, cutting edge roughness) using specialized scanning methods without the constraints of real-time monitoring, thereby resolving the contradiction between speed and measurement precision.
2Measurement precision
If offline quality control is performed by removing parts for inspection, then accurate quality assessment is possible, but productivity is reduced due to part removal and handling time
Solution Approach 1:
Quality control measurements are performed preliminarily during the cutting process interruption rather than after part removal. The scanning device measures quality features directly on the workpiece in situ, eliminating the need for part removal and handling. This resolves the contradiction by maintaining measurement precision while avoiding productivity loss from part removal.
Solution Approach 2:
The system performs self-inspection by automatically scanning and evaluating quality features of the workpiece without requiring external removal or separate inspection processes. The cutting system itself provides the quality control function through integrated scanning and evaluation, eliminating the need for separate part handling and inspection operations.
3Measurement precision
If the cutting process is continuously interrupted for quality checks, then quality control precision is improved, but productivity decreases due to increased non-productive time
Solution Approach 1:
Instead of continuously interrupting the cutting process for quality checks, the system performs partial quality control by scanning only after the first partial processing operation. This partial action provides sufficient quality assurance while minimizing interruptions to the overall cutting process, thereby resolving the contradiction between quality control precision and productivity.
Solution Approach 2:
Quality control is performed preliminarily after the first partial processing operation rather than continuously throughout the entire cutting process. This preliminary quality check identifies potential issues early without requiring multiple interruptions, maintaining quality precision while reducing total non-productive time.
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 direct post-process quality control, reduces unproductive time, and improves process reliability by allowing for early intervention in poor cutting quality, minimizing rejects and optimizing cutting parameters based on real-time feedback.
Implementation Method 1
at least one detector arrangement for detecting radiation reflected from the scanning area and/or emitted, especially thermal, radiation
Implementation Method 2
high-power laser cutting device with a 4 kW laser beam
Implementation Method 3
the working laser beam is adjusted with regard to the focus diameter in such a way that it is smaller than the cutting gap width
Data Source
Figure 1~2
Figure 3
Figure 4a~4b
AI summary
A method and a device for checking laser cutting processes in the high-power range greater than 1 kW average power provide for automatic quality control after the interruption and/or completion of a cutting process carried out with predetermined cutting parameters. The cutting process is interrupted after a first part-processing process, whereupon at least a section (K1, . . . KX) of the processing route is scanned. This is preferably done at a higher speed than that for the first partial machining operation and preferably close to or on the same machining path. At least one quality feature of the processing result is automatically determined on the basis of the scan result and compared with predefined quality specifications. Depending on the result of the comparison, an error message can then appear, processing can be aborted, a defect can be reworked, at least one cutting parameter can be adjusted and the cutting process can be continued with the changed set of cutting parameters.