Lumber Complex of the Future–Part VIII: the Rough Mill Process

The conventional rough mill is a crosscut first sequence with cut lines determined by the machine operator based on visual examination of the lumber. Future rough mill process concepts include microprocessors to make decisions and direct process control equipment; elimination of operator decisions based solely on a cursory, visual examination of the lumber; maximizing yield from each piece of lumber within the requirements of the cutting bill; maximizing overall yield at the lowest unit cost using computer-generated cutting requirements; and flexibility to handle a variety of lumber characteristics, cutting bill requirements, and processing options. Packages of lumber move to the unstacker for breakdown. The lumber then moves through the brand sensor which “reads” the brand and recalls the data concerning each individual piece. A computer decision is made as to whether a piece of lumber should be ripped first or crosscut first. A computer-controlled conveyance system moves the lumber. If the lumber is a crosscut first piece, it moves to the control sensor. This sensor reads the brand, recalls the cutting sequence developed by the computer, and actuates the cutoff saw and feed system. The lumber is crosscut into pieces of various length as specified by the cutting sequence. These short pieces then move to the control scanner and new data on size and defect characteristics are read into the computer. The computer develops a ripping sequence. The control scanner then actuates the gang ripsaw and feed system. The four blades of the computer-actuated gang ripsaw are set based on information from the control scanner and the computer-generated ripping sequence in order to maximize yield. At the ends of both lines there are off-bearers to stack the blanks, perform a quality control inspection, and send any usable pieces of wood to the salvage saws. At the salvage station there are both a conventional cutoff saw and ripsaw.

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