Формирование коаксиальных полей остаточных напряжений в полотне круглой пилы

Abstract

The working tool of machines with circular cutting units is a circular saw, the condition of which largely determines the quality of material processing. Circular saw blades in the process of operation are subjected to a complex effect of force and temperature factors that cause elongation and deformation of the saw blade, and the occurrence of internal stresses that take it out of the flat form of elastic balance and reduce the tool’s performance. The ability of saws to resist these factors is determined by the rigidity and stability of the saw blade. It is customary to consider a circular saw blade consisting of three zones: peripheral, middle and central. The middle part has the greatest influence on the stability of the saw blade. Initially, after manufacturing, the saw blade has a flat shape of balance, which can be disturbed by any external impact on the saw during the cutting process. The balance disturbance causes the blade and the cutting edge of the saw to deviate from the initial operating condition and reduce the accuracy and quality of wood processing. In order to prevent the influence of external forces, coaxial zones of plastic deformation of a certain width are formed in the middle part of the blade. In this case, under the influence of the created stresses, the effect of web tension appears. In world practice, two methods of forming such zones are used: forging and rolling. The creation of normalized stresses in the circular saw blade is carried out by local mechanical contact action of the working body of the saw tool on the steel saw blade in certain places of the middle zone. Compressive stresses compensating the forces of centrifugal acceleration, the thermal heating of individual zones of the saw blade, the external longitudinal and transverse bending forces that occur in the blade during wood processing are formed in the treated annular zones. The considered methods for creating annular zones of plastic deformation fields involving mechanical action on the saw blade have significant drawbacks, the elimination of which requires fundamentally new technical solutions. It is proposed to form coaxial fields of residual stresses of the saw blade by thermoplastic action consisting in creation of normalized residual stresses in the saw blade by concentrated thermal action on local annular zones coaxially located along the saw blade for the entire thickness of the saw. The formation of coaxial circular fields of residual stresses in the circular saw blade is simulated. The considered method of saw preparation will increase its stability in the process of operation.