Log centering apparatus and method using transmitted light and reference

Abstract

A log centering apparatus and method are described employing an optical log scanner for determining the longitudinal axis of the log for optimum wood product production by transmitting light to detectors through the space between the side of such log and reference edge members. The detectors each include a linear array of photosensitive diodes which are electronically scanned to take a reading. Before scanning, rough centering arms clamp the log and its opposite ends are engaged by rotation spindles. The log may be rotated intermittently or continuously during scanning to measure at different angles the distance between the reference edge and the surface of the log at a plurality of points spaced longitudinally along the log. These distance signals are fed to an electronic computer to compute the optimum yield axis of such log. The spindles on which the log is rotated are moved horizontally and vertically after determination of its optimum axis, to reposition the log until such optimum axis is in alignment with a reference axis, spaced a predetermined distance from a work axis, such as the lathe of a veneer lathe. The preferred embodiment of the invention is a veneer lathe charger. After repositioning the log in alignment with the reference axis, such log is reclamped and held while the spindles are removed so that the ends of the logs can be engaged by pivoted pendulum-like transfer arms which transfer the log from such reference axis to alignment with the lathe axis.