The common characteristics of cast steel are high melting point, poor fluidity, large shrinkage, easy oxidation and inclusion. During casting, the gating system is required to have simple structure, large cross-sectional area, fast and stable mold filling, and the flow strand should not be dispersed, which is conducive to the sequential solidification of castings and feeding of risers, and should not hinder the shrinkage of castings. Most factories use bottom pouring ladle with good thermal insulation performance and strong slag resistance. When pouring with bottom pouring ladle, the pouring system must be open, and the sprue is not filled to ensure that liquid steel will not overflow outside the sprue. The gating system type of the seat body shall be determined according to the above principles.
The sectional area of each component of the gating system is determined based on the sectional area of the cladding hole and with reference to the following gate ratio, Σ S-bag hole: Σ S straight: Σ S horizontal: Σ S internal = 1: (1.8 ~ 2): (1.8 ~ 2): (2.0 ~ 2.5). The sprue adopts circular section. It is determined that the cross-sectional shape of the sprue is circular. The sprue of large steel castings is mostly circular. The size of their respective sprues is shown in Figure 1.
Thus, the riser size is calculated by cubic equation method. In order to increase the local cooling rate of the casting, cold iron is placed inside the cavity and on the working surface. Therefore, according to the above analysis and calculation, a more reasonable gating system scheme is designed, as shown in Figure 2; The bottom deluge ingate layout is adopted. Four ingates are arranged at the bottom of the casting and two cold irons are used.