| 摘要 |
PURPOSE:To decrease tensile stress owing to thermal impact and to prevent the breackdown of a nozzle, by providing fine grooves for absorption of thermal expansion on the inside circumferential surface of a nozzle consisting of a material having good corrosion resistance for continuous casting over the entire length. CONSTITUTION:>=1 piece of fine grooves 1 are provided longitudinally from the top end to the bottom end of the inside circumferential surface of a nozzle of a material, such as zirconia, having good corrosion resistance but poor spalling resistance. The fine grooves may be annular or spiral from the top to bottom ends at a suitable pitch or may be a combination thereof in addition to the above-mentioned shape. In either case, the provision of the grooves uniformly over the entire part is preferable. The width of the grooves 1 is the value obtained by dividing the rate of expansion owing to a temp. rise by the number of the grooves 1. The depth thereof is determined by calculating the point where the max. temp. difference DELTAT in the system is equal to the tensile strength of the material because the tensile stress owing to thermal expansion is proportional to the DELTAT. |
