微小径エンドミルを用いて加工された溝の送り直角断面形状

抄録

Profile errors of grooves milled with a micro square end mill are discussed in this paper. Very low stiffness of micro end mills causes inevitably those errors to depress the productivity. Upright errors on both side walls of a groove are caused by transient chip formation on twisted cutting edges, that is, cutting point moves from the groove bottom to the shoulder at an engaging cross section of a groove, where uncut chip gets gradually larger in width. In the other hand, uncut chip width gets gradually smaller at disengaging cross section of a groove. Thus changing chip volume at both side walls forces the change of elastic deflection by the difference of normal cutting force component on both cutting edges. It results in upright errors on both side walls. Additionally, the end face of an end mill is inclined by normal cutting force, and it makes the concave bottom surface with an ellipse sloping down to a down-milling wall, because the largest cutting force toward the tool axis acts on a cutting edge at a rotating angle over 90deg. from engaging point.