ALPS – a new automated log and lumber processing system for hardwoods

During conventional production of solid wood furniture parts, logs are first sawed into lumber having defects randomly located throughout the board. The lumber is then remanufactured and the defects removed by ripping and cross cutting. The process is labor intensive, and saw kerf losses alone waste substantial volumes of lumber. This paper proposes an Automated Lumber Processing System (ALPS) which produces the same parts more efficiently. In ALPS, logs are scanned by computerized axial tomography to locate internal knots and establish log geometry without destruction. Using these data, the computer determines the log positions needed to maximize grade or value yield and automatically positions and turns the logs as needed, activates the sawmill dogs and carriage stroke, and sets feed speeds. Many boards, however, will still contain defects (i.e., knots, wane, stain, worm holes, checks) which must be removed. After drying and superficial surfacing, boards are scanned for defects by video image analysis methods. The computer identifies defect types, provides data on their location, and defines board geometry. ALPS then uses the image-derived defect data to compute an optimum cutting pattern for each board, thus yielding the maximum number of parts for a given cutting bill. Parts are cut from the board by a numerically controlled high-power laser directed by the computer-derived optimum cutting pattern data. Lastly, parts are automatically sorted for size. Residue material is chipped and used for fuel.

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