Investigation of the formation of a machined surface profile during end milling with a tool with a long overhang

Abstract

Purpose. Investigate the mechanism of forming the profile of the machined surface when milling with a tool with a long overhang. Methodology. Experimental method was used with a special stand, which makes it possible to simulate an elastic system of a part with different dynamic properties, record oscillograms of oscillations of a part and a tool during the cutting process. Milling was performed with a milling cutter with cutting modes in which self-oscillations occur. To determine the patterns of movement of the part and the tool, the method of aligning the fragments of oscillograms was used. Results. The scheme of the formation of the profile of the machined surface under the conditions of milling with self-oscillations by a tool with a long overhang has been investigated. It was found that the free vibrations of the tool after the tooth leaves the cutting zone have a higher intensity than that of the part. This affects the position of the infeed point on the cutting surface. To determine the period and range of self-oscillations of the cutter and the part, the section of the oscillogram with self-oscillations was straightened using the Savitsky-Galei filter. Comparison with the cutting surface of the sections of the oscillogram of the part and the tool during milling showed an identical vibration mode of the cutter. Based on the results of experimental studies, the deviation from the line of elastic equilibrium of the first wave of self-oscillation of the cutter was determined and a graph of its change was plotted. The studies performed have confirmed the previously established effect of deviation from the elastic equilibrium position of the first self-oscillation wave during counter milling on the shaping of the treated surface. Originality.  It has been established that the profile of the machined surface when milling with long overhang end mills is directly related to the deviation of the tool from the elastic equilibrium position during self-oscillation. Practical value. The obtained results show the effect of a tool with a long overhang on the formation of a machined surface during milling with self-oscillation.