Based on one hydraulic valve body and two hydraulic multi way valve body, the design method of casting and pouring system is introduced, and the casting system model of valve body is established. The casting process of valve body is simulated by using casting simulation software ProCAST, the position and size of casting defects in casting process are predicted, and the casting defects caused by different pouring temperature are analyzed According to the influence of subsidence, the following conclusions are drawn:
(1) During the filling process of the casting, when the liquid metal just enters the cavity, the filling is not stable, resulting in splashing; and because the cavity of the multi-channel valve body casting is complex, the flow resistance is large, the phenomenon of multiple streams of liquid intersection occurs, but in the later filling process, the pouring is gradually stable, which can effectively prevent the formation of air entrainment and slag inclusion defects.
(2) During the solidification process, the casting solidifies from all sides to the inside, and shrinkage defects appear at the last solidified part of the casting.
(3) When the pouring temperature is 1360 ℃, the maximum porosity is the smallest, and its value is 0.634; when the pouring temperature is greater than 1360 ℃, the maximum porosity increases rapidly, and then it basically remains around 0.95. Therefore, when the casting material is QT500-7, the most suitable pouring temperature is 1360 ℃.
(4) Because the volume expansion of nodular cast iron caused by graphite precipitation during solidification can compensate for some volume shrinkage, the shrinkage volume of QT500-7 is much smaller than that of steel-304.
(5) In view of the problem of shrinkage in the casting process of valve body, the structure of valve body was improved. The maximum porosity of the improved valve body was 31.4%. Compared with the valve body before the improvement, the shrinkage defects of the improved valve body were reduced, and the porosity was reduced by 2.9 times.
(6) For the two-way hydraulic multi-channel valve, due to the complex structure of the multi-way valve body, there are many narrow and long special-shaped holes and grooves in the complex inner cavity valve body with high integration degree, forming hot spot, which makes the shrinkage resistance of the casting larger during solidification. There are many shrinkage positions in the valve body, and the maximum porosity is 72.7%.