The gating system is used to guide the liquid metal into the cavity. According to the casting structure, technical requirements and alloy type, we should select the structure type of the gating system, determine the location of the introduction, calculate the cross-sectional area size, etc., so as to design a reasonable gating system. The reasonable design of pouring system is related to whether the metal liquid can fill the mold cavity smoothly, and whether the metal liquid will produce defects such as sand flushing, air entrainment and turbulence in the process of filling the mold cavity. The design of the pouring system shall follow the following principles:
① Guide the liquid metal to fill the mold smoothly and continuously, and can not directly impact the core;
② Control the flow direction order in the filling process to ensure that the casting contour is clear and complete;
③ Fill the cavity at a suitable time to avoid the formation of sand inclusion, cold separation and other defects;
④ It is simple and reliable with the ability of slag retaining and overflowing;
The pouring position of the casting is the position of the casting in the mold when pouring. It directly affects whether the liquid metal can fill the whole mold cavity smoothly, avoiding defects such as “insufficient pouring”, “cold separation”, “air entrainment”, “sand flushing”, etc.; in the solidification process, whether it is conducive to realize the feeding of the liquid metal, avoiding defects such as “shrinkage cavity” and “shrinkage porosity” etc. The structural features of the cylinder head andfeatures in this project are analyzed. The lower part of the cylinder head includes thin-walled inlet, exhaust and water channel structures which are difficult to form. The top surface of cylinder head belongs to the last part of metal filling, and it is also the machining plane. The casting defects (oxidation inclusions, etc.) on the top of casting can be removed by increasing machining allowance. Therefore, the casting should be discharged vertically. Three pouring positions can be determined for selection.
(a) Adopting the top air inlet side casting scheme, it belongs to the top casting type, with short filling time, which can guarantee the filling energy smoothly, and opening the inner gate at the top of the casting, which is conducive to the sequential solidification and meets the feeding conditions, and the top casting type has the advantages of convenient modeling and simple structure.
(b) Compared with the first pouring scheme, the water inlet is more evenly distributed, and the rising rate of liquid level is more gentle, but there will be metal liquid intersection in the middle, which is prone to casting defects such as inclusions, air entrainment and turbulence.
(c) The Pouring Scheme on one side of the bottom is adopted, the water enters from the bottom, avoiding the direct impact of the metal liquid on the molding sand, and the liquid level rises much more smoothly. However, compared with the previous two top casting schemes, it does not conform to the principle of sequential solidification, and the bottom is prone to shrinkage porosity, shrinkage cavity and otherdefects.