The pouring position of sand mold casting is the position of the casting in the mold during pouring. It directly affects whether the liquid metal can smoothly fill the cavity of the whole mold, so as to avoid casting defects such as “insufficient pouring”, “cold shut”, “air entrainment”, “sand flushing” and so on; In the solidification process, whether it is conducive to realize the feeding of liquid metal and avoid the defects such as “shrinkage cavity” and “shrinkage porosity” of sand castings.
The structural characteristics and sand casting characteristics of the cylinder head in the project are analyzed. The lower part of the cylinder head contains thin-walled inlet, exhaust and water channel structures that are difficult to form. The top surface of the cylinder head belongs to the last part of metal filling and is also the machining plane. The casting defects (oxidation inclusions, etc.) on the top of sand castings can be removed by increasing the machining allowance. Therefore, castings should be discharged vertically.
As shown in the figure, three pouring positions can be determined for selection. Figure (a) adopts the top air inlet side casting scheme, which belongs to top casting. The filling time is short, which can smoothly ensure the filling energy. In addition, the inner gate is set on the top of the sand casting, which is conducive to sequential solidification and meet the feeding conditions. At the same time, the top casting has convenient modeling and simple structure. Figure (b) adopts the pouring scheme with symmetry on both sides of the top. Compared with the first pouring scheme, the water inlet is more evenly dispersed and the rising rate of liquid level will be more gentle, but there will be liquid metal intersection in the middle, which is prone to casting defects such as inclusions, entrainment and turbulence. Figure (c) adopts the Pouring Scheme on one side of the bottom, and the water enters from the bottom to avoid the direct impact of liquid metal on molding sand, and the rise of liquid level is relatively gentle. However, compared with the previous two top casting schemes, it does not comply with the principle of sequential solidification, and the bottom is prone to shrinkage, shrinkage and other casting defects.