Ensuring the quality of rolled titanium zinc (TiZn) metal sheets used for roofing and wall panels in building construction is a demanding process, not in the least because the metal sheets have a reflective surface that makes identifying the appropriate imaging technology for an inspection system a priority.
Another challenge is the application’s location in a rolling mill, where high temperatures (around 60°C), dust, lubricants, aerosols, vibration, electromagnetic interference, and light interference are all present.
Now, Wise Technologies (Ljubljana, Slovenia) has developed a system that can manage inspections under these conditions. Dubbed Wise SCAN, the system consists of two imaging modules that can scan the complete width of the metal sheets. Each module incorporates two Basler Vision Technologies (Ahrensburg, Germany) GigE linescan cameras that acquire images of the sheets from both the top and the bottom.
Each imaging module also has illumination sources positioned and configured in such a way that flaws on the metal sheets can be distinguished with enough contrast to allow reliable defect recognition. One of the modules contains an encoder that triggers the cameras based on the speed of the production line and the length of the metal sheet. The cameras typically deliver nearly 19,000 lines/s at full resolution.
The Wise SCAN system can inspect the quality of the sheet before it is wound into rolls or cut into plates. It can also be used to detect several types of defects including mechanical damage, burnt oil, stabs, and edge defects. The inspection system has eliminated the need for six workers in two shifts providing manual labor, while helping to ensure the quality of the final product.
-- Posted by Vision Systems Design