Method to prevent shrinkage cavity and porosity of female rotor

Abstract

The invention provides a method for preventing hole shrinkage and shrinkage looseness of a casting. The method comprises the following steps of S001, making sectional sand into a sand core by using anadditional material manufacturing technology; reserving a cooling passage in the additional material manufacturing process of the sand core; S002, assembling a plurality of sand cores to form a groupcore; pouring the metal liquid into a die cavity formed by the group core until the die cavity is fully filled with the metal liquid; S003, introducing low-temperature gas into the cooling passage sothat metal liquid is gradually cooled to form the casting. The invention also provides a method for preventing hole shrinkage and shrinkage looseness of a female rotor. The special cold iron for temperature lowering is not needed, so that the cooling cost is reduced; during the temperature lowering on the metal liquid, the temperature can be timely lowered through controlling the gas pressure ofthe introduced low-temperature gas and the specification of the cooling passage by aiming at different specifications of castings; the occurrence of problems of hole shrinkage and shrinkage loosenessof the casting can be prevented.

Description

technical field [0001] The invention relates to the technical field of casting, in particular to a method for preventing shrinkage cavity and porosity of castings and female rotors. Background technique [0002] Materials generally expand when heated and contract when cooled. When the casting is cooled and formed, it also shrinks, resulting in a reduction in the volume of the casting. Under normal circumstances, when the casting cools and shrinks, it will be replenished again by molten metal. However, when the casting is not cooled uniformly, the local molten metal will condense first, and further surround the uncondensed molten metal to form a closed cavity. When the uncondensed molten metal cools and shrinks, it cannot be supplemented by external molten metal, thus forming shrinkage cavities or shrinkage porosity. In order to prevent shrinkage cavity or shrinkage porosity of castings, chill iron or riser or a combination of both are generally used. [0003] Due to the ...

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Problems solved by technology

[0005] However, due to the special shape of some castings, special cooling iron must be used on the surface of the casting, but the cost of the special cooling iron is very high, and some castings cannot be placed on the cooling iron

For example, the female rotor includes a shaft and blades, so it is impossible to place a general-purpose cold iron, and the cost of making a special cold iron is too high, and the problem of shrinkage cavity or porosity cannot be solved simply by relying on the riser

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