| 摘要 |
<p>PURPOSE:To control the outer diameter in the longitudinal direction with high accuracy, by controlling the rotating speed of the roll at the next stand basing on the difference between the value of bulge width measured at a specified roll stand and the reference bulge width, in elongating a hollow blank pipe by a mandrel mill. CONSTITUTION:In elongating a hollow blank pipe 14 by a mandrel mill equipped with plural stages of roll stands, the bulge width of a pipe material are respectively detected by sensors 34, 35 provided to the exit sides of the (i)th stand 33i and the (j)th stand 33j. The detected signals are analyzed by a bulge width measuring device 36 to calculate the changing rate against the reference bulge width by a host arithmetic device 37, and to calculate the rotating speed for adjustment against the reference speed of the grooved rolls 17 at the (i)th stand 33i. Basing on said calculated results, the main motors 31 of the (i)th stand are respectively controlled through a main motor controlling device 32 to adjust the rotating speeds of respective rolls 17, thereby the outer diameter in the longitudinal direction of a blank pipe 18 to be fed to a finish mill is finished highly accurately.</p> |
