Abstract: In order to study the change rule of chip breaking limits in high speed machining, chip breaking experiments are performed by using the representative turning insert with 3D complex groove at eleven normal and high cutting speeds. Based on the analysis of the experimental data, the chip-breaking limit curve and the common-character chip-breaking limit curve are obtained. The relationship between cutting speed and critical feed rate and the relationship between cutting speed and chip breaking region are analyzed by the method of cubic spline function interpolation and their mathematical models are built by the method of quadratic polynomial fitting and cubic polynomial fitting. Then, the mathematical model with least error and easy calculation is chosen. The results of the cutting experiments show that the critical depths-of-cut is a constant value at various cutting speeds, and the curve of critical depths-of-cut is a perpendicular line. Therefore, the new mathematical model of the critical depth-of-cut is built. Combining with the representative turning insert with 3D complicated groove, the change rule of the critical feed rate is studied and the predictive model is deduced. The establishment of the chip breaking limit curve and the mathematical model of 3D complicated grooved insert lays a theoretical and experimental basis for the future investigation of the chip breaking mechanism of turning insert with 3D complicated groove in the field of high speed machining.

Key words: Critical depth-of-cut, Critical feed-rate, High speed machining, Mathematical model