| 摘要 |
PURPOSE:To obtain billets of a good square section from ingots having a trapezoidal section by providing camber-preventing guides in the inlet and outlet of the 1st pass formed of a roll pair having calibers and selecting the roll diameters of the respective passes according to the sizes of rolled materials. CONSTITUTION:In the stage of rolling a billet of a square section from a casting ingot of a trapezoidal section produced by continuous casting, the 1st pass is formed of a roll pair having calibers. Freely rotatable guiding rolls 10 and horizontal guiding rolls 12 are provided on the inlet and outlet sides of the 1st pass to suppress the upward camber of a material 13 to be rolled. The material is rolled at >=30% draft by the 1st pass. Further, the material is rolled in the respective passes by setting the roll diameters in the respective passes in such a way that the ratio Ld/Hm between the average value Hm of the height size on the inlet and outlet sides in the corresponding passes of the material 3 and the projected size Ld of the length of the contact surface of the rolling rolls and the material 3 in the rolling direction attains >=0.5. The abnormal increase in roll surface pressure is prevented by the above-mentioned method. |
