| 摘要 |
<p>PURPOSE:To provide a piercing method of a seamless metallic tube which can carry out piercing of a high tube expanding ratio stably without generating troubles such as choking, outside flaws of a tube, poor engagement and so forth. CONSTITUTION:Disk rolls 3u, 3d are arranged obliquely in non-parallel with the outlet face angle theta2 of main rolls 1A, 1B at a skew angle DELTA to a pass line X-X to the sides of cone-shaped main rolls 1A, 1B positioned on the rotatively approaching side to a disk roll sliding surface for a billet and the following two conditions are satisfied about the skew angle delta, the outlet face angle theta2 and the inlet face angle theta1 to realize >=1.15 tube expanding ratios. theta2+2 deg.<8<9 deg., delta+theta1<12 deg..</p> |
