| 摘要 |
<p>A method for forming an elbow by cutting forms the hole of the elbow by performing the following steps: a step for forming in a material a starting hole having an uncut section left on the hole surface; a step for finishing the inner diameter of the portion of the starting hole (11-3), which is located on one side thereof, using a side cutter (II) provided with a circular arc-shaped cutting edge and having an outer diameter smaller than the diameter to which the hole is to be finished, the side cutter (II) being operated in such a manner that the cutter is revolved while being rotated in an attitude tilted in a predetermined direction relative to the material (12), the revolution of the side cutter (II) being performed in such a manner that the cutter moves along the hole surface to be finished; and a step for finishing the inner diameter of the portion of the starting hole (11-3), which is located on the other side thereof, by revolving and rotating the side cutter (II).</p> |
