在美国研制连续浇铸的早期,就已经知道中间包的塞杆不能适应连续浇铸来自盛钢桶的大批钢水。当时还怀疑,当从开浇到结束浇铸的全部时间由于输送时间长,保存提前运来的钢水以及盛钢桶中的真空除气而延长时,连续浇铸盛钢桶中的普通塞杆是否还适用。而且,在盛钢桶中甚至用最好的氧化锆注管也不能连续浇铸几百吨,因采用吹氧或机械方法来去除注口上的凝结金属或氧化物时,可能使它过早地损坏。平常,还希望以比改变中间包中的钢水液面更快的速度来改变浇铸速度。为此,美国钢铁公司研制了 Earlier in the development of continuous casting in the United States, it was known that the tampon of the tundish could not accommodate the continuous casting of large quantities of molten steel from ladle steel. At the time, it was also suspected that when the entire time from pouring to completion of casting was prolonged due to the long delivery time, the preservation of the molten steel supplied in advance and the vacuum degassing in the ladle, Be applicable. Moreover, even hundreds of tons of continuous casting can not be continuously poured into a ladle even with the best zirconia injection tubes, and the use of oxygen blowing or mechanical means to remove condensation metal or oxides from the nozzle may prematurely damage it . Normally, it is also desirable to change the casting speed faster than changing the molten steel level in the tundish. To this end, the United States developed a steel company