A simple calculation model of cutting forces in consideration of cutting edge roundness

摘要

In finishing, cutting edge roundness has to be taken into consideration in cutting process because the roundness can not be ignored at small undeformed chip thickness. The purpose of this study is to propose a simple calculation model of cutting forces acting on a blunt cutting edge at the small undeformed chip thickness in orthogonal cutting. In this study, an equation of equivalent rake angle of a cutting tool with a large cutting edge roundness was formulated from experimental equivalent rake angles. The experimental equivalent rake angles were estimated from cutting forces acting on a blunt cutting edge by using the relationship between the rake angle and the direction angle of resultant force without effects of the cutting edge. Then cutting forces were calculated from the equation of equivalent rake angle and the relations among the cutting process parameters without effects of the cutting edge and they were compared with actual cutting forces. As a result, the conclusions obtained in this study are as follows. First, the equivalent rake angles obtained by cutting tests using some radii of cutting edge roundness were unified into the same relationship by normalizing the undeformed chip thickness with the radius of cutting edge roundness and they approached to their nominal rake angle at large undeformed chip thickness, respectively. Second, assuming that shear stress on shear plane was constant, cutting force including effects of cutting edge roundness resulted in dividing into two components: cutting forces acting on rake face and on flank face. Third, the cutting forces acting on a blunt cutting edge predicted by the proposed calculation procedure approximately coincided with the actual cutting forces.