| 摘要 |
PURPOSE:To finish an edge of a round hole of a formed article by fitting a cone drill, through self-adjustment, in the center of a round hole by means of a cushion coupling and performing chamfering. CONSTITUTION:When a cone drill 4 is gradually elevated under rotation from below so as to be fitted in a round hole 6 of a formed article 5, even if there is some discrepancy in position between the drill 4 and the round hole 6 and also discrepancy between an interval Po' between two cone drills 4 and an interval Po between two round holes 6, the center of the drill 4 is brought into congruence with the center of the round hole 6 due to its eccentricity caused by a cushion coupling 3 after being guided by means of the taper shape of the drill 4 so that the uniform pressure is put on the drill 4. Right chamfering can thus be performed. |
