我厂过去浇铸麻纺机T字龙筋,因缩孔而报废的很多,缩孔地位大都是在转角的热节处,研究结果,确定是原来用的明冒口有问题,因为明冒口与空气的接触面太大,以至在铸件冷缩以前,冒口表面己经凝结成一层硬皮,失去了补缩作用,为了缩小冒口与空气的接触面,用浇口圈做了一只小孔冒口罩(如图1),把它扣在冒口上面, Our factory in the past casting T-spire dragon tendons, due to shrinkage and retirement lot, most shrinkage in the corner of the heat Festival, the results of the study to determine the original use of the Ming riser problems, because Ming riser and The contact surface of the air is so large that even before the shrinkage of the casting, the surface of the riser has been coagulated into a layer of crust which loses its effect of shrinkage. In order to reduce the contact area between the riser and the air, a small Hole riser cover (Figure 1), buckle it in the riser above,