| 摘要 |
<p>PURPOSE:To roll a seamless steel tube in which an uneven metal scarcely exists in the peripheral direction with mandrel bars of the number being as small as possible by executing the rolling by inclining and arranging roll shafts of a pair of caliber rolls in the same directions against the advance direction of a stock to be rolled, at the time of stretch reducing of the stock to be rolled, into which the mandrel bar is inserted and rolling it. CONSTITUTION:BY inclining and arranging a roll shaft against the advance direction of rolling, a wall thickness distribution can be equalized in the peripheral direction. Its inclination angle theta1 is arranged in the same direction in a pair of roll stands. A gap between rolls 1, 1' being roughly uniform in the peripheral direction and a mandrel 3 is demarched, and a steel pipe 2 whose wall thickness is uniform in the peripheral direction is obtained. Also, since the inclination direction is the same direction, rotational force works in the reverse direction to the steel pipe by a pair of rolls 1, 1', and a rotation of the steel tube 2 can be prevented. In such a way, since an outside diameter pitch of the mandrel bar to be retained can be set roughly, the number of retaining pieces of the mandrel bars can be curtailed remarkably, and a variable of wall thickness in the peripheral direction can be prevented at a low cost, and also, simply.</p> |
