|The online newspaper for the forest products industry including loggers, sawmills, remanufacturers and secondary wood processors.|
Culp Lumber a Leader in Sawmill Innovation
Company’s advanced Southern Yellow Pine mill embraces SteadyScan from Advanced Sawmill Machinery
By Alan Froome
Date Posted: 8/1/2003
NEW LONDON, North Carolina — Few sawmill owners or managers are willing to be the first to install a new machine or control system. They want to have all the bugs worked out and see it working somewhere else first. But for advances to be made, someone has to take the risk and be
The Culps are a family of some of those rare people who are willing to take risks in new technology, and over the years they have earned the respect of their
One of Culp’s many innovations over the years was its use of the first Advanced Sawmill Machinery (ASM) built sharp chain, which was installed on the primary log breakdown line in 1994. ASM, based in Holt, Fla., is well known today for its sharp chain systems; since that first one built for Culp, ASM has sold over 100 systems.
ASM recently installed another new technology at the Culp mill — its new SteadyScan log transport system. SteadyScan is a patent-applied-for log conveying system that is designed to eliminate log roll and movement when passing logs through a scanner for computer optimization. The ASM SteadyScan log transport system cradles the tree securely and runs on an accurate, machined keyway in order to hold the stem still as it travels on the conveyor.
At Culp Lumber Co., the ASM SteadyScan is running on the tree-length optimum log bucking line. “In this case, Culp was in fact the second mill to purchase the SteadyScan transport system,” said AMS president David Seffens, “but they added their own ideas and specifications. Our first SteadyScan system was installed at New South Industries in Camden, South Carolina.”
If there is any log movement in the scanning zone, the measurements — diameters, sweep and shape — captured by the scanning process will be incorrect; the resulting cutting solution will be wrong, and lumber recovery will suffer.
Basically, if a log rolls while passing through the scanning zone, the scanner will ‘read’ the diameter larger than it actually is or show more sweep, and the optimizer will select incorrect lumber sizes for the machine to cut. The SteadyScan system also contributes to accurate scanning for shape and crook. Data for log diameter, length, shape and crook are used in computing a bucking solution to recover the highest value from each log.
“Recovery has improved, and in combination with the new Perceptron Tri-Cam scanner, we are seeing much more accurate log diameters,” said David Richbourg, manager of the Culp mill. “Length bucking accuracy is also very tight and is now
The mill only produces 20-foot products in 6x6; dimension products are 16-foot maximum length. Therefore, the bucking system must find log segments with diameter and sweep characteristics that produce 20-foot 6x6 with a maximum side board of 16 feet or a single 20-foot 6x6. Any side board longer than 16 feet will be cut back at the trimmer, diminishing recovery.
The Perceptron Tri-Cam scanner sees nearly 360 degrees of the log’s cross-section; the log passes through a ‘doughnut’ configuration scanner before the data is outputted to the optimization computer. The previous single-array Lasar camera scanning system, from its position mounted overhead on a roof truss in front of the bucking station, could see 130 degrees of the log.
“We studied many conveyors and made a lot of sketches before finalizing the design with ASM,” said David. “All the small details are important — the angle of the flights, the pitch spacing of the cradles, and so on. To work properly, the system has to carry both the smallest diameter straight log and the largest crooked log without movement through the scanner. We felt the best combination from a wear standpoint was to use cast steel cradles running in a stainless steel pan. In fact, we use stainless steel conveyor pans almost everywhere in the mill.”
“We tinker more with the bucking system parameters than most other systems in the mill to maximize the benefits and to keep our lengths tight,” David added.
At Culp Lumber Co., stems up to 60 feet long are transported through the Perceptron Tri-Cam laser-camera Scanner; the overall length of the system is about 120 feet. After the scan data is collected, the Perceptron optimization system calculates the optimum bucking solution and outputs it to a log bucking system that has four movable saws.
The transport system runs at 400 feet per minute but is capable of 500 feet per minute, according to David. “The steel log cradles run on stainless steel keyed chainways that are machined in 20-foot-long sections on our two-head milling machine. This ensures that any future replacement chainway sections will be interchangeable.”
The SteadyScan system at New South Industries features a chainway with special plastic wear strips instead of stainless
The SteadyScan log transport cradles fit precisely over a v-way. They typically are spaced at 30 inches or 36 inches and carried on a 6-inch pitch 155B chain. Sprockets are nominally 40 inches in diameter with 20 teeth, and the chainway is lubricated by a timed injection of oil, similar to a sharp chain system. The chain is driven by an AC Vector variable speed electric drive that has a rotary encoder to accurately measure and track log lengths as they pass down the conveyor. Occasionally, the conveyor may need to be reversed and the encoder count must be adjusted, so the drive train is hydraulically tensioned to remove any backlash. To load and unload the conveyor, logs are kicked on and off the SteadyScan chain. Kicking off is achieved using an overhead sweep kicker to scoop the logs out of the chain cradles and into the pocket below the multiple buck saws.
Culp Company History
Culp Lumber Co. is located in New London, some 40 miles northeast of Charlotte. The company was established at this site in1925 by the late Henry Culp, who passed the business onto his son, Henry W. Culp Jr., president of the company. The third and fourth generations of the Culp family now are working at the sawmill: vice president Hank Culp (Henry W. Culp III ) and his daughter, Amy Culp-Shelton secretary-treasurer. George Culp, Hank’s brother, is also involved in the company business.
The sawmill has been upgraded regularly as technology has improved. The most modern layout was in 1984 when a twin bandmill sharp chain system was installed for primary log breakdown. A new planer mill was built in 1991, and the first version of the optimum bucking system was started up in 1996.
The mill was expanded in 1998, and a new head rig and 36-inch log carriage were installed in order to process logs that were too big for the sharp chain system. In 2000 a new dry kiln was added followed by a Coe Newnes lineal edger system in 2002.
“We harvest trees within a 100-mile radius of the mill and cut 60 percent of our logs with our own crews,” said David. “The remainder comes from contractors. We use Hydra-Ax feller-bunchers, John Deere and Franklin skidders and Huskie and Prentice Loaders.”
Logs up to 25 inches in diameter and 8 to 20 feet long — plus some larger ones — normally are processed on the head rig. Production is around 80 million board feet annually, or about 380,000 per shift. The mill runs one 10 hour shift a day and employs a total of 85 people, including 12 truck drivers. Principal products are 1x4, 1x6, 2x4 through 2x12, and 4x6 and 6x6 timbers. Lengths produced are from 8 to 20 feet in 1 foot increments, which is unusual in the Southern yellow pine industry.
Culp Lumber Co. is very active in the stewardship of forest resources and employs several foresters to ensure that trees are replanted and the timber supply is being managed sustainably.
The general layout of the Culp Lumber Co. mill, starting at the log yard, comprises:
• Fulghum 120 foot log crane with AC Vector winch and wheel drives
• Nicholson A-4 27-inch capacity ring debarker
• Goring-Kerr metal detector
• CTC optimum log bucking system with Perceptron Tri-Cam scanner, four movable 72-inch saws, ASM SteadyScan transport conveyor system, and Redwood Electronics Opti-Buck camera to position the zero saw relative to the end of the stem.
• ASM sharp chain system with USNR Letson & Burpee 6-foot twin air-strain bandmill and twin canters with Key Knife chipping system for primary log breakdown
• USNR Letson & Burpee 6-foot twin air-strain bandmill and twin canters with Key Knife chipping system, Hemco V-6 laser scanner, and Coe Newnes-McGehee skewing table infeed with spiked edger type through chain to square off cants
• Salem 6-foot horizontal bandmill to resaw the cants with Land-East inertial separator outfeed table
• USNR-Ukiah two-saw optimized edger with Hemco V-6 scanner and USNR Timbergraphics optimization software
• Coe Newnes-McGehee three-saw lineal edger with Key Knife reman head
• USNR Log Boss carriage with 36-inch opening, three knees, plastic wheels and IESCO 250hp DC drive
• USNR- Hemco S-332 trimmer with saws on 1-foot centers, Hemco V-6 scanner
• USNR-/Hemco 89-bay sling lumber sorter
• Lunden lumber stacker with auto stick placer, using laminated and hardwood sticks
Culp Lumber Co. also is equipped with six Taylor THD-360 forklifts, which have 36,000 pounds of lift capacity. The mill has a saw filing shop with two full-time employees who maintain the bandsaw blades and Key Knife tools used on the canters.
The filing room is comprehensively set up with:
• Two Iseli BC-1 CNC saw grinders (RH)
• Iseli BC-1 CNC saw grinder (LH)
• Iseli type STA auto swaging and shaping machine
• Gockel G-50 traveling head grinder
• Armstrong auto saw leveler
• Two Armstrong # 4 stretcher rolls
• Newman-Whitney GS-100 carbide knife grinder
Variable pitch, variable depth bandsaw blades are supplied by Oleson Saw Technology, which also supplied most of the above filing room equipment. IKS, Simonds and Cut Technology also supply blades.
The mill operates two dry kilns, a 68-foot Irvington Moore double-track kiln that is direct fired by a McConnell shavings burner, and an 86-foot CTC-Culp designed double-track kiln that is fired by a 65 million BTU Ed Bahr Services burner and features 12 76-inch fans with AC variable frequency drives.
The planer mill consists of:
• USNR-LSI double-pack infeed tilt hoist
• Newman M-990 16-knife planer/matcher with shop-built infeed and Quietcut spiral carbide heads
• Northern Milltech digital in-line moisture sensor
• Lucidyne 300 grade mark reader
• USNR-LSI double-bank trimmer
• Lucidyne 100 grade mark reader
• Claussen eight-arm grade stamper
• USNR-LSI 30-bin sorter
• USNR-LSI package maker with secondary lift
• Signode air tool strapper using 5/8-inch polyester strapping
• Newman-Whitney SS-30 machine to turn cut blocks into shavings
Advanced Sawmill Machinery
Advanced Sawmill Machinery was started in 1994. It is located on a 38-acre site in Holt, Fla. with 30,000 square feet of shop and assembly area. The company is equipped with CNC precision quality machine tools and laser cutting tables.
Company president David Seffens is largely an experience-taught engineer who continually comes up with better sawmill machinery designs. Ideas and designs are typically customer driven in the first instance, then refined by David and his staff to achieve the customer’s intent with the simplest, most practical equipment.
In addition to sharp chains and the Steady-Scan transport system, Advanced Sawmill Machinery also builds curve sawing systems, canters, edgers, tilt hoists, trimmers and carriage drives.
The company currently is under contract to build seven log preparation machines of its own unique design for veneer slicing of exotic woods. These are some of the most complicated machines it has designed to date. They have sophisticated computer controls supplied by Tri-Delta of Alabama.
For further information about Advanced Sawmill Machinery, call (850) 537-5333.
Do you want reprints or a copyright license for this article? Click here
Research and connect with suppliers mentioned in this article using our FREE ZIP Online service.