Abstract:

The size effect of flat end mills based on the ternary cutting force model is checked, and then a simple method estimating coefficients of cutting force is explored. The effect of helical angle on cutting force is proved to be negligible when cutting depth is little, then a simplified ternary mathematical model of force for single tooth of flat end mills is built. Based on this model, the instantaneous cutting thicknesses for every tooth are compensated with tooth run-out, and data of cutting experiments are used to fit the linear equations of peak cutting forces with cutting depth and instantaneous cutting thickness for every tooth, their R-squares are found to be near 1 as a whole, this indicates that the coefficients of cutting force for one tooth be constant, which means that the size effect of flat end mills be not significant. Accordingly, the average peak force of tool is used to estimate cutting force, with this estimation method, tool eccentricity need not to be considered, and calculation is rather simple, its simulated force waveform is close to the measured, which indicates that the estimating method be rather effective. These research results can be used as reference in the research of size effect for milling force, and in the application of flat end mills.

Key words: cutting force, estimation, linear fit, size effect, flat endmills