| 摘要 |
PURPOSE:To prevent the breakage of a solidified shell, cracking of a core, etc. by providing many gas ejecting holes in the outside circumferential part of the core and disposing independently paths for supplying the ejecting gas and passages for cooling fluid in the core. CONSTITUTION:A core 7 consists of a hollow cylindrical outside body 11 and an inside body 12 which is concentrical with said body and has an open top end. Paths 16 for supplying an ejecting gas and passages 14 for cooling fluid are independently provided in the body 12. The pressure and flow rate of the gas ejected from gas ejecting holes 13 are adjusted to optimum values separately and independently from the pressure and flow rate of the cooling fluid of the core. The holes 13 are further made gradually larger in the drawing direction of a billet and the compressive stress to be exerted from a shell to the core is adequately decreased. The compressive force to the core 7 is decreased by the pressure of the ejecting as in the above-mentioned method, by which the drawing of the billet is made easy and the breakage of the shell, etc. are prevented. |
