Tree-D Compact 3-D Optimization Retrofit Eliminates Costly Relocation of Upstream Log Handling Equipment
NEW AUGUSTA, Miss. — Mark Parish did not expect to become the manager of a sawmill.
After earning a Bachelor of Science degree in forestry at the University of Arkansas-Monticello, he planned to be a forestry manager. But management talent is highly transferable so when Mark was recruited to mill management in 1985, he took the opportunity.
Sixteen years later, Mark is the manager at the Georgia-Pacific Corp. Leaf River mill in New Augusta, Miss. He has held the position since 1997, and he has found it to be a good fit.
New Augusta is a town of about 700 residents in southeastern Mississippi. The Southern yellow pine sawn for lumber at the Leaf River mill comes both from Georgia-Pacific plantations and private forest lands in the sparsely populated region.
Leaf River has used optimization technology throughout its mill for some time. The mill had single axis scanning and optimization for its primary breakdown equipment, but it wanted togo to a three-dimensional system. Optimization technology has improved by “leaps and bounds”
since he first got involved in it in the early 1990s, noted Mark.
Last fall the Leaf River mill added a new optimizing system, the Compact 3-D Optimization Retrofit, designed and manufactured by Tree-D Inc. of Tallahassee, Fla. A signature feature of the Tree-D system is that it is amenable to retrofitting an existing, relatively short infeed.
Given the depth of his experience in mill management, Mark is very familiar with sawmill equipment and machinery, including optimization systems. He explained some of the considerations that resulted in the choice of the Compact 3-D.
The company selected the optimizing system from Tree-D for a very specific reason, explained Mark. “Nobody else could retrofit (an optimizer) to a regular size Chip-N-Saw infeed.” Tree-D could do it with its system, and that meant Leaf River could avoid the cost of relocating all its upstream equipment.
The sophistication of the Compact 3-D system has provided the good results and operational simplicity that Mark sought. “It’s an easy system to use on a conventional Chip-N-Saw with good resolution,” he said, and the Compact 3-D can be quickly set up. “I’d buy another one tomorrow,” he added.
The Compact 3-D gets a real workout at Leaf River. The mill runs five days per week, 20 hours each day. Mark has found the Compact 3-D system to be “pretty-bullet proof.”
In 2001, in a publication titled “A Look at Our Manufacturing Facilities,” Georgia-Pacific reported production of 100 million board feet with 112 employees at its New Augusta mill. Much of the Southern pine dimensional lumber produced by the mill goes to construction applications.
Most of the lumber produced by the Leaf River mill is shipped to companies to be treated. A significant volume of material also goes to re-manufacturers to be used to make roof trusses for buildings.
At about the same time the Leaf River mill began to control its primary breakdown line with the Compact 3-D, it switched to a smaller diameter log. The typical log now is about 6.8 inches in diameter, according to Mark, and yields about 37 board feet of lumber.
The Tree-D system generates analytical reports and diagnostics almost effortlessly, according to Mark. Tree-D industrial grade computers using the QNX™ operating system run the Compact 3-D system. According to Ralph Bennett, one of the four partners behind Tree-D, the Compact 3-D computer system is networked to a separate reports computer operating under a Windows™ platform. The reports computer allows users to control all the operating parameters and to print shift reports; it also houses the database repository that allows log and production data to be stored for access at later times for mill performance analysis.
Ralph grew up in Eugene, Ore. where he developed deep roots in the timber industry by serving 25 years with a West Coast based engineering firm. In 1985 he moved to Florida where he linked up with Harry Qualls, an experienced systems integrator and computer programmer. The two wrote a computer program designed for the very early optimization systems.
The early systems were designed around slow pre-Pentium 386 and 486 computers that did their work off-line by producing look-up tables that were loaded into mill systems controlling the infeed lift and shift as well as the chipping heads and saws. The look-up tables were based on simplified round, straight, constant-taper shaped logs, which were the only shapes available from the light curtain scanners in use during that period. In those days, solution times per log were equivalent to as much as 15 feet of log travel. Real-time solutions came much later as computer technology advanced. For example, most Tree-D log solutions now only require 4 to 5 inches of log travel.
Anxious to capitalize on the quantum advances in computer technology, Ralph and Harry joined forces with two more men, and the four of them launched Tree-D. The other two principals of Tree-D are Robert Mayer and Steve Bellenot, Ph.D. Mayer, an electrical engineer with years of experience designing electronic sensing products, provided the expertise required to develop 3-D scanning technology to complement Tree-D’s optimization software capabilities; Tree-D has applied for a patent for the T-260 series scanners as a result of his efforts. Bellenot, a professor of mathematics at Florida State University, developed the demanding mathematical aspects of the lumber pattern solver software that does the fitting of high value lumber into the log images.
The Tree-D team, now equipped with real shape, real time log scanning and lumber pattern solving capabilities, wanted to find a way to bring 3-D optimization to existing systems without the expense of retrofitting long double-length infeed equipment. Thus, the Compact 3-D concept was born.
The Tree-D Compact 3-D System requires mounting two Model T-261Q Quad Head Ring Scanners to an infeed bed that has been extended or replaced so that it is at least 4 feet longer than the mill’s longest log. This additional length requires minimal changes to up-stream log processing equipment. Longer lengths are recommended if space permits.
Additionally, centering rolls and a vee-rail style wear bar and chain must be added to the infeed. The centering rolls help steer logs to the center of the infeed, and the vee-rail style flights eliminate side movement of logs as they move forward and as flights wear. Bed shifting is also required to achieve the full benefit of the compact optimization system. Most mills have also added one or more additional press rolls on the bed extension to help control logs as they enter the infeed. The centering rolls can be eliminated if the proper style auto-rotation equipment is installed.
The first quad-head scanner ring is placed about 2 feet downstream from the infeed tail sprocket; this distance is increased if mill space permits an infeed length longer than the required minimum. The second ring is located one-half the maximum log length downstream from the first scanner.
When a log reaches the second scanner, the system assumes it has been rotated and that the lead end of the log is stable as it moves forward. At that time, both scanners will begin recording 3-D rings of closely spaced points around the circumference of the log (true shape log profiles) at approximately 1-inch centers along the length of the log.
The optimizer recognizes that during this initial segment of travel, vertical or horizontal movement can occur as the longer logs continue to load onto the chain. Once the log tail end has passed the tail sprocket, it is assumed to be stable on the chain, and all subsequent rings represent the log in its true position as it enters the C-N-S or sharp-chain. The log travels forward in this stable mode until the lead end reaches a point as little as 2 feet from the head sprocket, where scanning action is terminated and the pattern solution process begins.
This process produces a combination of ‘stable’ and — on the longest logs — ‘non-stable’ rings. The ‘non-stable’ rings are obtained while the log is transitioning onto the infeed chain, and the ‘stable’ rings are obtained once the log is fully loaded onto the chain. Using the x and y positions from the ‘stable’ rings along with the x and y positions of the leading rings, the system interpolates a three-dimensional curve along the length of the log and realigns the ‘non-stable’ ring images accordingly. Since short logs are fully loaded on the chain before the scanning action begins, all their rings are ‘stable.’ U.S. and international patent applications for this unique process have been submitted.
Tree-D has installed six systems in the Southeastern U.S., and the mills have benefitted from significant improvement in lumber recovery and grade. All mills using this system have reported a very significant improvement in controlling such parameters as edge and face wane and lumber lengths. Three more mills have ordered systems to be installed by year-end.
One of the reasons that Leaf River chose the Compact 3-D Optimization Retrofit was that it was literally a retrofit system. The installation did not require a major re-engineering of existing mill equipment. Specifically, the Compact 3-D did not require a double-length infeed.
Ralph estimated the cost of the Compact 3-D Retrofit is about one-tenth the expense of installing a new, longer conveyor and relocating all the upstream log handling equipment.
The people at Tree-D are the sort you can count on to support the system, said Mark. As for maintenance, it amounts to little more than taking the time to check the calibration once a week.
In addition, for all the sophisticated technology built into the Compact 3-D, the system is “very user-friendly,” he said. “Once the parameters are set, the log comes in, and the Compact 3-D knows what you want out.”
Tree-D offers a full line of optimization software and scanning products for stem bucking, auto-rotation and primary breakdown, including curved cant sawing. The company has many mills successfully running one or more of its systems, some for several years.
For more information, contact Tree-D at (850) 906-9336 or e-mail firstname.lastname@example.org.