| 摘要 |
<p>A method of manufacturing a seamless tube by the invention can duly control the rotary forging effect without miss-rolling such as defective onset engagement with rolls by satisfying either of (1) - (3) formulas below, dependent on a given range of roll diameter ratio Dg / D1, prevent the occurrence of internal surface flaws at the top of the work material attributable to deteriorated hot workability, and further prevent the occurrence of said flaws over the remaining length without altering parameters for piercing-rolling process. Thus, the invention can be widely utilized as an excellent manufacturing method for said tube: in €‰€ƒcase €‰€ƒof €‰ €ƒD g / D 1 < 1.1 , 23 ‰¦ N / ( D f / 100 ) ‰¦ 40 , in €‰€ƒcase €‰€ƒof €‰€ƒ 1.1 ‰¦ D g / D 1 < 1.5 , 20 ‰¦ N / ( D f / 100 ) ‰¦ 44 , in €‰€ƒcase €‰€ƒof €‰€ƒ 1.5 ‰¦ D g / D 1 ‰¦ 1.8 , 20 ‰¦ N / ( D f / 100 ) ‰¦ 48.</p> |
