| 摘要 |
<p>PURPOSE:To prevent thickening of a pipe end after reducing with high accuracy by thinning the pipe end of a blank pipe at an entrance side of a reducing mill with high accuracy. CONSTITUTION:A reference thickness pattern in longitudinal direction of the pipe end after thinning rolling that can suppress the fluctuation of the thickness at the pipe end at the time of reducing is determined beforehand for each reducing schedule. Then, the change of an outer diameter pattern that occurs in longitudinal direction of the pipe end at the time of thinning rolling that obtains the reference thickness pattern is determined beforehand. At the same time, the thickness fluctuation given by the change of the outer diameter pattern to longitudinal direction of the pipe end at the time of reducing is determined beforehand. Then, the rolling pattern of thinning rolling for the hollow pipe is set by adding thickness fluctuation to the reference thickness pattern for the hollow pipe as an object of controlling. After thinning rolling by the rolling pattern, the thickness pattern and outer diameter pattern in longitudinal direction of the pipe end of the hollow pipe are measured and the difference between reference thickness pattern and outer diameter pattern and thickness pattern and outer diameter pattern is found. The reference thickness pattern and outer diameter pattern are corrected to make the difference zero.</p> |
