種々の切れ刃形状のドリルの切削抵抗と切りくず生成状態(第2報)

切れ刃形状の解析結果に基づく実験結果の検討

抄録

In the 1st part of this investigation, various shaped drills which have straight or circular cutting edges at the chisel edge portion and concave or convex cutting edges at the main cutting edge portion have been analyzed geometrically. Expressions for inclination angle and normal rake angle along the cutting edge have been obtained. In this paper, the experimental results on the cutting forces and chip formation such as chip flow angle and normal shear angle are shown and discussed on the basis of the results of geometrical analysis. It is possible to treat and explain qualitatively the cutting phenomena in drilling with various shaped drills under the given cutting conditions. It is found that the distribution of inclination angle along the cutting edge influences greatly on the formation of broken chips and the magnitude of thrust force, and Stabler's chip flow rule does not give the first approximate relation along the cutting edge when the main cutting edges of a drill are curved ones. Furthermore, as a result of the analysis and experiment, effective cutting edge configurations for the chip breaking and the reduction of thrust force are deduced.