A contribution to the research of circular saw lateral stability 1 Influencing parameters on the circular saw natural frequencies

The circular saw is the most frequently used woodworking machine. The main problem of using the circular saw is the lateral stability of the sawblade and the problems grow bigger with increased cutting speed and feed speed, and with decreased sawblade thickness. Sawblade behaviour during rotation and cutting is significantly determined by the natural frequency spectrum of the standing sawblade. In this study the research results of the natural frequency spectrum, some influencing parameters and damping characteristics of differenth designed circular saw blades in variable conditions are presented. The natural frequency spectrum was determined by using a standing sawblade. The influences of the following pammeters were investigated: 1. clamping ratio, 2. the characteristics of the contact area between the saw and the clamp, 3. damping. The standard measuring equipment for vibration and noise was used. One of the aims of this study was to develop a measuring method for the determination of circular saw blade damping characteristics. The measurment results show that the natural frequency spectrum of damped saws does not significantly change with additional damping (with a damping layer between the saw blade and clamp), but the accelerations of specific frequencies of undamped saws are reduced. Based on the measuring results it cannot be generally concluded what the influence of the clamping ratio (0,24 to 0,33) on the saw frequency spectrum is. It is shown that the restitution factor between the saw and a small ball can be used for the determination of the saw blade damping characteristics.