Drills for drilling holes from the side of metal plates having low hardness of stacked metal plates having different hardness, and a drilling method using the drill

摘要

PROBLEM TO BE SOLVED: To prevent the inner surface of the hole of a metal plate low in hardness from becoming rough due to rubbing by chips, and to prevent the opening end of the hole from being chamfered, when metal plates different in hardness are stacked to drill a hole.