| 摘要 |
PURPOSE:To collapse and remove the pores in the inside of a billet and to obtain a product having a square or circular cross section and an excellent quality, by performing the operations of subjecting the billet to rolling reductions first from both its long-side sides and successively from its short-side sides, once or more times. CONSTITUTION:In rolling a billet A having a rectangular cross section into a billet B having a square cross section or a circular one; as a method (1), the billet A is subjected to rolling reduction from both sides of its long sides till its short-side length attains the short-side length of a product B, and is successively subjected to rolling reduction from both sides of its short sides repeatedly till its long-side length attains the long-side length of product B. At that time, it is preferable to increase the rolling reduction as large as possible and to decrease the rolling speed as low as possible within an allowable range to collapse and remove the pores in the inside of billet A. As the other method (2); the operation of subjecting both sides of its long sides to rolling reduction in the 1st pass and then subjecting repeatedly its short sides to rolling reduction in the 2nd and subsequent several passes is repeatedly performed till the lengths of its long and short sides attain the lengths of short and long sides of product B. |
