| 摘要 |
<p>PURPOSE:To make easily and surely the wall thickness distribution in the longitudinal direction of a seamless pipe uniform by controlling a piercer, by obtaining the target wall thickness distribution in the longitudinal direction of a pipe obtained after piercing, required to make the wall thickness distribution of a roll-finished pipe at the exit side of a stretch reducer uniform. CONSTITUTION:As a blank material, a round steel bar 10 is continuously heated in a rotary hearth type heating furnace 12, and after piercing it by a piercing mill 14, the pierced blank pipe is stretched by a mandrel mill 20 and is successively drawn by a stretch reducer 26 after being reheated in a reheating furnace 24. In such a method of the wall thickness controlling of a seamless pipe, the wall thickness distribution of a roll-finished pipe 28 at the exit side of the reducer 26 is previously estimated to obtain the target wall thickness distribution in the longitudinal direction of the hollow rough blank pipe 16 obtained after piercing, required to make said estimated wall thickness distribution uniform. Then, the piercing conditions of piercer 14 is controlled so as to obtain said target wall thickness distribution.</p> |
