Among the process parameters associated with pouring characteristics, pouring time and pouring temperature are usually taken as variable parameters of process design. Among them, the pouring time is related to the mold filling speed of liquid metal, and reasonable pouring time can effectively avoid casting defects such as oxidation slag inclusion, insufficient pouring and cold insulation caused by eddy current. The reference value of pouring time can be obtained according to the empirical formula, as shown in the formula. However, the actual value should be determined according to the casting structure and production conditions.
Among them, “1” is the coefficient, which is related to the wall thickness of the casting, and “1” is the total mass of pouring liquid metal (kg).
The value of pouring temperature depends on the type of alloy, the main wall thickness of castings, the discharge temperature and pouring temperature of HT250 iron castings. For example, for the castings with the main wall thickness of 30-50mm, the pouring temperature is [1350, 1430] ℃, so there is a better pouring temperature, which can effectively avoid casting defects such as porosity and shrinkage. Secondly, the flow coefficient and the critical speed of liquid metal filling are related to the choke surface size, pouring temperature, gate type and gate section ratio, which can be adjusted by changing the structural parameters of gating system, feeding system and pouring temperature.