Bend Forms of Circular Saws and Evaluation of their Mechanical Properties

Abstract

A circular saw is able to operate properly only when its equilibrium form is stable. Usually it is a flat equilibrium form. In most cases the loss of stability of a circular saw is related to the loss of its dynamic stability. One of the reasons are resonance vibrations of saws. With appearing resonance phenomena, tiny forces cause great deformations. The size of these deformations depends on saw rigidity and damping value, therefore it is very important to know mechanical properties of saws (strength, rigidity, coefficient of damping, etc.). The elaborated study methods and equipment allow to evaluate precisely mechanical properties of saws, separate bend forms, resonance frequencies and damping. Using resonance frequencies, under which saw bend forms are close to theoretical, Young`s modulus was estimated for all four fastened saws (E = 230 ÷ 368 GPa). Using amplitude-frequency characteristics of saw vibrations, coefficient of damping was evaluated (tgδ = 0.00025 ÷ 0.01255). Bend forms of saws were also studied changing their fastening moment, respectively – 50, 100 and 150 Nm. The paper presents study methods, bend forms of saws and obtained relationships, reflecting the change of mechanical properties of saws.