Experimental Studies of Vibration Excitation During Turning

In this work, the mechanism of vibration excitation during longitudinal turning using a cutter–oscillator is analyzed. The research covers the entire process—from the first contact of the cutting edge with the allowance to the established cut. It is shown that oscillations of the cutter–oscillator caused by various excitation mechanisms can be observed within one revolution of the workpiece, both in the cutting area and during steady cutting, in the conditions of both continuous and discontinuous turning. It has been established that the section of initial cutting is present in any mode of longitudinal turning. Due to the elastic deformation of the cutter–oscillator system, a full cut to the depth of the cut is made in a few revolutions of the workpiece. The number of revolutions per cut‐in area depends on the stiffness of the system and does not depend on its mass, which determines the frequency of natural oscillations. With increasing stiffness, the number of revolutions decreases. In addition, the thickness and width of the cut metal layer significantly affect the number of revolutions of cutting: with an increase in thickness, the number of revolutions decreases, and with an increase in width, it increases. It is shown that the modes of turning (continuous and intermittent) do not affect the duration of cutting, and the cutting speed has an insignificant effect. It was also established that the static deflection of the cutter and its oscillating amplitude increase at each subsequent turn at the cut‐in area. At the same time, the cutting speed has a weak effect on the deflection, but it significantly affects the amplitude. During the research, four types of force loading of the cutter–oscillator were identified, each of which corresponds to a certain law of motion and a characteristic shape of the oscillogram. The purpose of the article is to carry out a comprehensive analysis of the excitation mechanism of the oscillating cutter–oscillator during longitudinal turning, starting from the moment of the first contact of the cutting edge with the allowance until the established cutting mode, taking into account various processing conditions (continuous and intermittent turning), and also reveal the nature of the excitation effects and the corresponding laws of the cutter movement.