| 摘要 |
Drill apparatus having a special drill bit with means for drilling a hole into the sidewall of a tube and upon withdrawal of the bit, for forming a flange around the drilled hole. Pins for forming the flange are movable in bores passing crosswise through the drill bit. When the rotating tip portion of the drill bit is withdrawn from the hole, the pins project from the drill bit to cause a flange encircling the hole to be formed. |
