Effects of Specific Gravity in Air dry Condition upon Cutting Phenomenon, Stress Distribution over Tool Rake Face and Frictional Coefficient on Interface between Tool and Chip in Orthogonal Cutting of Wood

摘要

In order to make clear the cutting mechanisms which are related to cutting forces, tool wear, machinability of workpice, cutting efficiency and so on, a more fundamental research under the actual cutting conditions should be carried out. For that purpose, it is important and necessary to make clear the actual stress distributions on the tool rake face. But few studies have dealt with the exact measurements of the stress distributions, and so, the main objective of this study is to obtain quantitaive information on them. In this study, the basic orthogonal cutting tests of wood were performed at 144.9 mm/min of cutting speed under various combinations of depth of cut (t) and specific gravity of wood in air dry condition (ru), using the conventional tool and the composite tool in order to make clear the influence of two factors on the cutting force components, the cutting phenomena, the stress distributions over the tool rake face and the frictional coefficients on the interface between the tool and the chip. The main results obtained are summarized as follows: (1) The distributions of the frictional stress (r) and the normal stress (o) over the tool rake face can be expressed by Eq. (7), and the variations of the values of the exponents and the coefficients used in this equation with ru are illustrated in Figs. 9 and 10. (2) On the basis of the experimental results (Eqs. (2), (3) and (5), and Figs, 8 and 9) obtained in the wood cutting tests, the cutting force ratios on the tool face near the tool edge to the total cutting force on the tool face can be calculated from Eq. (9), and these ratios are shown in Tables 2 and A-4. (3) The frictional coefficients (μ3) on the tool rake face can be expressed by Eq. (15). On the tool rake face,μ3 can be considered to be constant, and the values of μ3 are shown, comparing with the other frictional coefficients, in Fig. 12, Tables 3 and A-5.