TYPICAL THG LAYOUT CONFIGURATION
Fence Grade mark reader Check grader THG Trimmer
Lug loader Grade Projector display zone
Flat transpor t
Simpler is better. USNR’s THG utilizes a short, flat transport system to move boards through the scan zone. THG’s simple, level transport system is designed to accommodate the highest piece rates. In most mill layouts this configuration can easily be dropped into the existing flow for minimal disruption and minimal downtime (see layout above). THG’s transport system also features the narrowest of belts (pictured opposite page) to transport the boards through the scan zone, ensuring minimal obscuration of the bottom surface of the board. The sensors see as much of the bottom of the board, and the defects, as is possible with a transverse scanning system. This simple, well designed transport system means reduced capital cost and reduced requirement for ongoing maintenance that more complex transport systems demand.
LED illumination
Lighting is of utmost importance for any visual scanning system. Light must be spread evenly across the scan zone and devoid of any hot spots that require shielding. It must cover all 4 faces of the piece evenly and consistently, and it must be as white as possible to accurately image the colors of the board. It must also be reliable and not degrade over time. It should be simple to maintain and calibrate, and easily accessible to keep clean. USNR chose its LED lighting system for THG to meet all of these criteria. LED is a long functioning light source that is clean, stable and easy to maintain. THG is configured with four separate light bars to ensure even coverage over each face of the board, and is positioned off-axis for highlighting cracks and splits. Unlike other light sources such as halogen, LEDs don’t degrade over time and run relatively cool for reduced fire hazard.
www.usnr.com | ISSUE 4 - 2013 | Millwide Insider 11