| 摘要 |
<p>PURPOSE:To control the wall thickness and roundness of a pipe material, by stabilizing its rolling condition, by controlling the speed of mandrel mill roll, and offsetting the fluctuation of tension acting on a mandrel bar. CONSTITUTION:A mandrel bar 2 is inserted into a mandrel mill which rolls a pipe material 10 by rolls r1-rn. A tension acting on the bar 2 is detected by detecting a driving torque of a device 4 used for driving the mandrel 2. And the fluctuation of tension of the bar 2 caused by the fluctuation of said torque is cancelled and eliminated by controlling the speed of the rolls r1-rn. Thus the tension acting on the bar 2 is made constant, and the rolling condition is stabilized, and consequently, a product having prescribed wall thickness and roundness is obtained.</p> |
