Problem
One way to improve efficiency in plywood veneer mills is to examine logs and determine the largest possible cylinder. This allows the log to be positioned in the lathe to generate the greatest amount of useable veneer. Log curvature, limbs and cracks all complicate the problem. Furthermore, the solution must be found in real time as the log is moved into position on the lathe. Alpha Omega developed 3D real time modeling software for Coe Manufacturing Company veneer lathes.
Solution
The Coe veneer mill log measurements have seen three significant generations:
The first used CCD linescan cameras, with ordinary light as illumination. This system was in use in the early 1980s. It used upward-looking cameras to observe the log profile, essentially detecting the edge of the log's shadow. Multiple cameras observed the log's shape at eight locations along its length.
The next measurement technology was laser triangulation distance measurement. Laser illumination and image focal plane compensation combined to reduce measurement limitations of the earlier technique. Several of these spot-distance measurement devices are used in a log measurement installation to observe the log profile.
The present-day log measurement system is a laser-illuminated, scanning, triangulation distance measurement system. It observes hundreds of points along the entire length of the log, compared to the five-to-eight discrete measurement locations of the earlier systems. The scanners provide considerably increased measurement performance over the previous systems. The Coe Lathe Charger system now acquires a complete 3-D measurement of the incoming log in real time.
Results
The scanning program measures details as small as a fraction of an inch and determines crack depth to calculate the amount of partial and complete veneer sheets that can be produced from the log. The system produces a significant increase in efficiency and profit for the mill.
