bocal superior adaptado para ser disposto dentro de uma abertura de descarga de um distribuidor ou de uma panela

摘要

The present invention is directed to creating a less-energy loss or smooth (constant) molten steel flow with a focus on a configuration of a bore of an upper nozzle, so as to provide an upper nozzle formed with a bore having a configuration capable of to suppress deposit formation. For this purpose, in an upper nozzle 10 for allowing molten steel to flow therethrough, a radius of an upper end of a bore 11 is set to be equal to or greater than 1.5 times a radius of a lower end of the bore 11, and a bore surface 14 is formed in a vertical cross-sectional configuration represented by log(r(z))=(1/n)×log((H+L)/(H+z))+log(r(L))(n=1.5 to 6).