Effect of Grain Angle upon Change of Cutting Phenomenon, Stress Distribution over Tool Rake Face, and Frictional Coefficient on Interface between Tool and Chip in Orthogonal Wood Cutting

摘要

In the wood cutting process, it is important to obtain the actual stress distributions over the tool rake face during cutting and to investigate the changes of the stress behavior depending on the workpiece conditions, but few studies have dealt with the exact measurements of the stress distributions, and so, the main objective of this paper is to obtain quantitative information on them. The method of the measurement was based on the use of the composite tool which was divided into two parts parallel to a cutting edge in order to measure separately the force on one section of the tool (Figs.1, 3 and 4). Using this tool, the stress distributions over the tool rake face were measured directly in the wood cutting. The frictional coefficients on the interface between the tool and the chip during cutting were made clear based on the results of the stress distributions. The main results obtained are summarized as follows : (1) The distributions of the normal stress (σ) and the frictional stress (τ) over the rake face can be expressed by Eq.(16), and the variations of the values of the exponents and the coefficients used in this equation with grain angle (φ1) are illustrated in Figs.19 and 20. (2) On the basis of the experimental results (Figs.13～16) obtained in the wood cutting tests with the conventional tool and the composite tool, the ratios of the cutting force acting on the rake face length (lc) of the edge part T2 of the composite tool to the total cutting force acting on the conventional tool can be calculated from Eq.17, and these ratios are illustrated in Fig.23. (3) The frictional coefficients (μ) on the interface between the tool and the chip can be expressed by Eq.(18). On the rake face, μ can be considered to be constant, and the variations of μ with φ1 are illustrated in Fig.24.