Selection of casting position of nodular cast iron for automobile hub support

According to the actual production situation, the automobile hub support casting is produced by using the Japanese Xindong automatic pouring machine and the method of ordinary wet sand gravity casting. After analyzing the structural characteristics of nodular cast iron, the sand consumption and the specification of molding line sand box, the molding scheme of one box and two pieces is adopted, and the size of sand box is 600 mm × 700 mm × 380 mm。

The casting position is the position of nodular cast iron in the mold during the casting process. Choosing the casting position is usually the first step after determining the modeling method in the process design of nodular cast iron. It is a very important link in the design process. The reasonable casting position should ensure the sound nodular cast iron, simple modeling and core making, and convenient cleaning in the later stage. When designing the casting position, we should pay attention to making the important parts in a favorable position, estimate the positions prone to defects in advance, and take effective measures for these positions. Generally, the following principles need to be followed to determine the casting position:

(1) The important surface or part of nodular cast iron faces downward or on the side. Practical production experience shows that the upward surface is usually more prone to shrinkage porosity, pores and inclusions, while the lower part of nodular cast iron has better solidification and feeding effect due to the static pressure of the upper metal, which is conducive to obtaining smooth surface and dense structure.

(2) The large plane of nodular cast iron is inclined or placed downward. If necessary, the inclined casting method (such as horizontal sitting vertical casting, horizontal sitting inclined casting, etc.) can increase the rising speed of liquid metal and reduce sand inclusion defects.

(3) Usually, the thin-walled part is placed under the lower part of nodular cast iron or under the inner sprue to ensure the mold filling capacity of liquid metal and prevent cold shut or insufficient pouring.

(4) It is beneficial to realize sequential solidification. For the alloy nodular cast iron with large volume shrinkage, the thick part should be placed at the top of the nodular cast iron, so that the riser can be used for feeding later. If it cannot be fully met, the hot spot shall also be located on the side of nodular cast iron as far as possible to facilitate the subsequent feeding with side riser.

(5) It is conducive to the positioning and exhaust of sand core, and avoid the use of unstable hanging core or cantilever sand core.

(6) Try to keep the box closing position, casting position and cooling position of nodular cast iron consistent to avoid turning the mold after casting.

Therefore, based on the above principles, the pouring position of nodular cast iron is determined as the thick part most prone to hot spots, as shown in the figure.

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