| 摘要 |
<p>PROBLEM TO BE SOLVED: To make a taper rolling possible with a small bulging volume condition even if an end length of a pipe to be taper rolled is not sufficient to cover a distance between stands by providing a pipe outer diameter measuring sensor at an exit side of the stand for obtaining a tip end cross sectional area changing rate to be caused by a bulging, based on a measured value of the pipe, and for rolling the next pipe element by setting the number of roll rotations at a specific value. SOLUTION: The number of roll rotations (ΔN1+N) is set to satisfy a formula (ΔN1+N)=(N deg.+ΔN)×α×C. In this case, N is the number of a standard roll rotations of the stand,ΔN is an increased speed volume of the number roll rotations calculated from a law that a pipe element cubage is constant,ΔN1 is an increased speed volume of the proper number of roll rotations which does not cause a bulging, and C is a constant being determined by an operational data in the past. Also,αsatisfies a formulaα=(Dtop-t)/(Do-t), Dtop is an outer diameter of the pipe element tip end inclusive of the bulge, Do is an outer diameter of the pipe element and t is a thickness of the pipe element. The next pipe element is rolled at the number of roll rotations obtained.</p> |
