| 摘要 |
<p>PURPOSE:To control the finish outside diameter of a finish rolled pipe and to prevent surely the out-of-tolerance in the outside diameter of products by adjusting finely the outside diameter of the seamless steel pipe obtained by stretch reducing with a stretch reducer of 3-roll type by using sizers. CONSTITUTION:In a stretch reducer for seamless pipes which stretch-reduces a base pipe with a 3-roll type hot stretch reducer 26 arter heating the same in a reheating furnace 24, adjusts finely the outside diameter thereof with plural units of sizers 31 consisting of grooved rolls of 2 roll type which re synchronized with rolling speeds and are adjustable of rolling reduction, and allows the pipe to cool with a cooling head 30, the hot outside diameter Do and temp. To of the finish rolled pipe right after the outlet side of said sizers 31 are detected, and in a control device 36, a cold finish outside diameter Dc is determined from these detected values, and the gaps of the grooved rolls of said sizers 31 are controlled so as to eliminate the difference DELTAD1 between the Dc and a target outside diameter DT.</p> |
