Improvement Potential in Log Rotation

摘要

Several different log rotation methods are used at sawmills. They vary from manual log rotation to log rotation with a real time measurement. Furthermore, sawmills use different log rotation mechanics with different manufacturers. In general, all manufacturers have their opinions about the best log rotation technique for different sawing environments. For the best recovery, the standard deviation of the log rotation angle should be under 2 deg for optimal sawing, including value optimizing with tomography. The typical standard deviation value of automatic log rotation angles in sawmills varies from 10 deg to 15 deg . Therefore, there is much room for improvement in log rotation mechanics in order to get a maximal profit at this most basic and important stage of cutting logs. If and when the log rotation is not in control, the blame is usually put on the mechanical part of the system. However, our studies have indicated that all factors from the log conveyor to the computer communication between the subsystems have an effect on successful log rotation. This article discusses the aspects of rotation mechanics which affect the log rotation precision. Moreover, different log rotation methods used at sawmills are presented. Examinations and results of this article are based on log rotation studies at several Finnish sawmills during the years 2003 - 2005.