market, making the window of opportunity very short to shut down the line for the installation. “We had 11 days to rip the equipment out from landing table through the trim saws and install new hardware, transfers, THG system, Revolver Lug Loader, new landing table, etc. We worked 24 hours a day mechanically and 12 hours a day on the electrical side to get everything wired up. After install we still had the task of starting up the control and optimization systems and getting them tuned in.” Doug said the timing was absolutely challenging but the mill started producing on the scheduled production date. He commented that it was a very good start up.
and with increased production. Though the performance tests haven’t yet been done he is confident the THG is ready. “We’ve passed three inspections by the grading bureau (Western Wood Processors Association – WWPA) and we’re seeing all of our grade out percentages tracking nicely to our projected targets.” Doug is convinced that as the software continues to progress and the mill gets better at tuning for its products, the system will continue to improve the mill’s fortunes.
THE IMPORTANCE OF PITH
Harry Ogloff, USNR’s product manager for automated planer grading systems, explains the importance of the THG’s proprietary end grain scanner in determining accurate knot sizing. “The purpose of the end grain scanner is to measure the grain at the end of the board to determine which part of the log the board originated from. Knowing the part of the log the board came from is critical to accurately determining how the surface knots are connected within the material. The end grain scanner along with other attributes of the material allows the THG to not only view the knots from the material surfaces, but also know how these knots are interconnected inside the material.” He went on to say that one key attribute for structural grading is the amount of knotty material that exists in a given cross section of the board. In a log, the knots typically will converge toward the pith (center of the log). To determine the volume of knotty material in a board and assess its structural properties it is essential to know how the surface knots connect inside the board. The end grain scanner provides important data to assist the optimizer in that determination.
How the system works
The new USNR equipment supply begins with the MillTrak camera controlling the backlog to the Revolver Lug Loader. Once in lugs the boards are transported on a narrow, flat transfer through the THG scan frame where they are scanned for the mill’s specified defects. The THG’s belted scanner transfer is a key advantage over competitive transverse systems that require elevation changes and tend to obscure the boards during scanning. The THG scanner transfer is a simple, flat transport system that completely stabilizes the boards on thin belts that carry the boards through the scan zone. These thin belts ensure the BioLuma 2900LVG+ sensors see as much of the four surfaces of the board as possible. The THG scanner is fitted with two rows of sensors positioned off-axis both above and below the transfer; in this way all four surfaces of the board can be scanned utilizing only two rows of sensors. As well, the THG utilizes an end grain scanner positioned at lumber line that scans the end of each board, and provides the THG’s GrainMap™ technology with measurement data to identify the pith location relative to the board for highly accurate knot sizing capability. (See sidebar at right.) The THG software classifies the defects on each board and assigns it a grade based on the size and location of the defects together with the mill’s grade definition inputs. The check grader and Grade Projector are located immediately downstream from the THG scan frame. As the boards exit the scanner the grade and trim solutions are projected onto the surface of the board for the check grader to view; he can either
Speaking from experience
Today the Glendale operation has reduced its grading contingent from four manual graders down to one check grader. Doug speaks from experience when he says he is pleased and impressed with the performance of the THG. “I’ve dealt with some other automated grading systems and they have taken quite some time to get things tuned in to a comfortable level. Above and below grade are very important to us and those tend to be finicky and take some time to get tuned in, especially with the product mix in dimension mills. This system started up on time, and we started seeing the grade out numbers consistently filter into the percentages that we wanted. We also started to see our production numbers increase within a short time of start-up. We were pretty impressed with that.” He continued t ?^ Z[? ] H?YH?]\?\]X[ H\??????] \? [?] ?\? ?] HX[?X[ ?\?[K?][?H???\?[???\? ?\?[H ?\?Y \? [YK[? ?H ?\?Y ?YZ[?? H?YH?]?[X?\?????\?[? H?[ \?[?? H \??[?Y?\? ] ?H ?[?Y ??H ?\?H ?] H[\ ?\??Y ?] ] ??????\?????H T??QH
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