Applying the finite element method to drill design based on drill deformations

The design of the twist drill with special cross-sectional shape using the finite element method based upon drill deformations was presented in this paper. In order to improve the unfavorable distribution of the total orthogonal rake angle along the primary cutting edge of a thick web drill, a thick web drill with curved primary cutting edges was devised. The profile of the curved primary cutting edge was mathematically determined by changing the distribution of the tool orthogonal rake angle along the primary cutting edge. A three-dimensional finite element analysis based upon the drill deformations was applied to obtain the ''secondary'' flute shape and to specify the web thickness, the helix angle, and the flute length. The effect of these geometric parameters on drill deformations was also investigated. Experiments were conducted to evaluate the drill's cutting performance. Experimental results indicated that the thick web drill with curved primary cutting edges was effective in reducing the thrust force, the torque, and the tool wear, a strength that definitely provided a better cutting drill and longer tool life for drilling the JIS S50C heat-treated steel.