| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for rolling raw tubes for seamless steel tube manufacture by which rough tubes having an equivalent or better wall thickness distribution are obtained, compared with the ease where a fixed shoe is provided even if a Piercer mill provided with a roller shoe is used. SOLUTION: In the Piercer mill a plug is contacted with the top surface of the round steel slab traveling horizontally among a pair of skew rolling rolls up and down, and concurrently when the round steel slab is surrounded with a pair of roller shoes right and left, and rolled, perforated into tubular shape, the clearance (δ) formed by the skew rolling rolls surrounding the round steel slab and the roller shoes in sectional view at gouge position is designed to be 20 mm or less to roll the round steel slab so that the load ratio imposed on the pair of roller shoes right and left is within the range of 0.9 to 1.1.
|
