Modeling and analysis of variable-core groove for integral cutting tools

Abstract

With good stiffness, the helical groove with variable-core radius has been widely used for end mills, drills and other integral cutting tools. However, ground by five-axis grinder, its machining process is high cost and time consuming. Thus, this paper reports a graphical analysis method to obtain the structure parameters and geometric shapes of variable-core grooves with the known wheel geometry and position before the practical machining. The wheel movement during the machining process is firstly decomposed into three simple motions and modeled as a translation matrix. Then, a family of wheel surfaces is calculated and the groove cross section line is deduced by splitting the surfaces with a cross section plane. Accordingly, the normal section line of the groove is expressed by a series of scattered points, which are the intersections of the normal section plane and the helical curves generated by the points on the groove cross section line which moves along the wheel trajectory. All the mathematic models are programed by Matlab and verified by experiment. Finally, the key parameters of the variable-core groove, including the rake angle, groove width on the cross and normal sections and the departure distance between the cross and normal groove section lines, are analyzed from the tool bit to the hilt.