Impact of Circular Saws Surface Hardness and Thickness on Coefficient of Damping

Abstract

During sawing, under the influence of different forces and saw speeds close to critical, resonance vibrations occur. Seeking to increase the stability of saw, it is important to estimate saw bend form, the vibration amplitude and vibration damping time (coefficient of damping). Having estimated vibration damping time, it is also possible to forecast the change of kerf size in time. The paper presents study results of four 9XФ circular steel saws of longitudinal sawing, the diameters of which are 400, 500, 800 and 1000 mm, as well as five 9XФ circular steel saws of transverse sawing, the diameter of which is 400 mm. Amplitude-frequency characteristics, resonance frequencies and saw bend forms (modes) were ascertained. The variation of coefficient of damping within frequency range and its distribution in the points of saw plane were estimated. The variation of saw thickness was estimated within 0.12 mm – 0.25 mm, while surface hardness within 7 HRC – 10 HRC range respectively. The coefficient of damping as well as the relationship between saw surface hardness and thickness were evaluated. It was found, that the coefficient of damping is inversely proportional to the variation of surface hardness of saw material. Estimating the ratio between saw thickness and surface hardness, it was found, that the value of coefficient of damping is preconditioned by surface hardness.