自从1984年约翰·威廉用砂芯在暗冒口的金属壳内做出一个孔的方法成为专利以来,暗冒口就一直在铸钢工业中得到广泛的应用。暗冒口的工作原理是:用“爆竹”芯在暗冒口凝固时所形成的钢壳上捅出一个孔,这个孔让大气压力推动暗冒口里的金属液,使其补缩铸件。如果没有爆竹芯,即使存在定向凝固所需的整个温度梯度,暗冒口也不会补缩铸件。暗冒口失效是很麻烦的,因为通常不易发现它的失效,尤其是用侧边暗冒口时更是如此。切除冒口后,铸件的缩颈部位常常较为致密,而在冒口下面或离冒口接触面一定距离的部位处会出现缩孔。在许多情况下, Since 1984, when William made a hole in the stinking metal shell with a sand core patenting, the stubborn mouth has been widely used in the steelmaking industry. Dark take the mouth of the working principle is: Use “firecrackers” core in the dark riser when the solidification of the steel shell formed by the poke out a hole, the hole to atmospheric pressure to push the metal in the dull mouth to shrink casting. Without a cracker core, even though there is an entire temperature gradient required for directional solidification, the obscuration nozzle will not contract the castings. Dead-stoic failure is troublesome, as it is usually not easy to find its failure, especially with the dark side of the riser. After removal of the riser, the constrictions of the castings are often denser, while shrinkage occurs at or below the riser at a distance from the contact surface of the riser. in many circumstances,