By Jennifer McCary
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Travis says that the decoupling of the canter and gang saw eliminates many problems that occur during simultaneous chipping and sawing. And because these functions are separate, troubleshooting is also simplified. The ASM sharp chain transport system combined with the downward motion of the conical heads secure the cant positioning so that it does not shift during the cut. "If you are chipping from the side," Travis observes, "The side pressure will move the cant. You can optimize all you want, but if you can't hold that log where you've placed it, you have lost everything you have paid for."
(top) Two-sided cants proceed through ASM curve canter. (bottom) ASM sharp chain transport for cants.
Every log processed at the sawmill goes through the curve-sawing canter. Thus, Travis Lumber is able to saw on the curve and recapture those impressive yields on 100% of its log furnish. Cants over 10. inches or those with defects can be re-routed on the canter outfeed to a linebar resaw, with the majority of cants proceeding to the ASM 800 HP 10 in. bottom arbor curve-sawing versa gang. Studies of the resource base indicated that the 10 in. opening would be able to handle all but a small percentage of the total raw material. Average log diameter is 7 1/2 inches.
An angled and moveable linebar is positioned to within 2 inches of the saws on the gang's infeed table. The linebar adjusts to the curve of the cant and can be offset as much as 12 inches. Initially, the linebar was stationary with a 3 inch offset. "We found out that we could put more curve in the log with the canters than we thought originally." explains Travis. "Then to get that curve through the gang we had to have a linebar that could move with it."
ASM, Inovec, and Travis modified the system in March and picked up another 2-3% increase in yield. Fluted feed rolls keep the cant positioned against the linebar for precise feeding of the curved cant through the saws. A crowder roll ensures that the cant's leading edge remains against the angled linebar. Once the press rolls gain control of the piece, the back of the linebar in front of the gang infeed moves out of the way. So instead of the saws moving to adjust to the curved cant, the cant is skewed relative to the saws, based on its curved profile. According to the manufacturer, the curve sawing theory at the gang is very similar to the manner in which a planer works.
Direct coupled hydraulic motors on the feed and press rolls keep the system simple and straightforward. After a great deal of research, ASM contracted with Precision Tool and Die, Shreveport, La., to custom manufacture the arbor, lube and guide system. The result, according to Travis, has been exceptional saw life.
Side view of ASM curve-sawing gang
The gang's sawing module is a single arbor with two banks of saws. As the cant advances the module shifts to the desired pocket based on cant size. The large bank is equipped with 28 in., 120 plate blades with .140 in. kerf. It saws 4 and 6 in. cants. This provides savings in target sizes while ensuring the gang's reliable and trouble-free operation. The system has operated a year with no downtime and no saw or guide problems. Now, with a year's worth of operating data, managers are ready to start experimenting with kerfs and arbor speeds to hopefully tweak another 2 to 3% increase in yield.
Travis is careful to note, however, that as good as this new technology is, the upgrade would not have been successful had any part of the overall project been left out. Upstream modifications at the tree-length log cutup system included adding a second 74 in. cutoff saw; installing an ASM rotary log kicker and turner, which turns the small end first to feed the mill; and installing a Baldor PLC vector drive. The new PLC allows Travis lumber to process 15 logs per minute on one cutup line, which translates to 400 FPM. A Caterpillar 966 feeds logs to the merchandising line, which begins with an ASM self-centering infeed and 30 in. Cambio debarker, before stems are kicked onto the high speed bucking line.
To accommodate the expanded products that would be possible after completion of the project, 30 bays were added to the HEMCO sling sorter, bringing the total number to 67 bays on the green end. TLC's product mix now includes 5/4 inch decking, 4x4 inch and 4x6 inch timbers, 1x4 inch through 1x8 inch and 2x4 inch through 2x12 inch lumber in lengths from 4-20 feet.
"If you're going to make a commitment to thin kerfs, high speed production and curve sawing, you've got to make a commitment to put the equipment in the file room to do the job right." Travis states. Nobody at the mill ever had any exposure to thin kerfs or curve sawing. So early on, head filer Emmett Jones and green end supervisor Jerry Craig started doing their homework to learn all they could about it. Jones and his circle saw filer attended training classes at Sabine Valley Vocational Tech. He also studied all the filing room equipment on the market to determine what would best suit their needs.
In the end, the filing room upgrade included six new machines. "Mr. Travis spared no expense," says Jones. "If any of us in the filing room thought we needed something, he got it." Circle saw equipment includes a Vollmer dual side grinder, Vollmer top and face grinder and Simonds circle saw leveler. Remaining equipment purchases include a Simonds band saw leveler, Simonds band saw tensioner and an IMW guide grinder.
Filing room is upgraded with six new machines.
Saws are changed twice a day and aluminum guides are also changed every time the saw is changed. Jones notes the decision to go with aluminum guides has worked out extremely well. Although he has ordered 40 saws, Jones reports only 20 blades had to be replaced in the first year of the curve-sawing gang's operation.
On any given day, the four-man staff will work on 19 bands and 44 carbide saws. In addition to Jones, the staff includes two band filers, a carbide man and a knife grinder.
the story continues...
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