Design of gating system for casting process of cast steel joint

In casting production, gating system is one of the important factors that affect the quality of castings. According to the characteristics of cast steel joint castings, the basic principles of our gating system are as follows:

(1) Ensure that the molten steel entering the cavity is stable and free of eddy current.

(2) The reasonable pouring position should be selected to facilitate the sequential solidification of castings.

(3) The gating system shall not cause thermal stress on the casting.

(4) Ensure that the molten metal has a proper rising speed in the mold during the pouring process.

(5) The structure of the pouring system shall have the ability of exhaust and slag retention.

There are many calculation methods of the gating system. At present, the main application is the calculation of the gating system in subcontracting and plug bar. The latter is divided into the calculation method of pouring weight speed and the calculation method of rising speed of molten steel. The former and the latter’s calculation method of pouring weight speed are mainly suitable for small steel castings produced in large quantities. It is rarely used in large steel castings. The calculation method of liquid steel rising speed is suitable for large steel castings. This paper adopts the method of calculating the rising speed of molten steel.

Calculation method of rising speed of molten steel. According to the weight and structure of the casting, the required rising speed of the molten steel is determined, and the pouring time of the casting is calculated according to the selected hole size. According to the height of casting and pouring time, the rising speed of molten steel is checked.

The size of cast steel joint is huge and the production cost is very high, so the scrap rate should be as low as possible in the production process. Therefore, it is necessary to simulate the casting process of cast steel joint to realize the pre casting. The solidification simulation is based on the numerical simulation technology of the filling and solidification process of the casting. It can be used for solidification analysis, flow analysis and coupled calculation of flow and heat transfer of castings. The casting temperature, casting speed, casting time, molten steel demand, cooling time in sand mold and other process parameters were determined, and the tendency of shrinkage cavity and porosity was predicted. It plays an active role in improving and optimizing the casting process, improving the casting quality, reducing the scrap rate and ensuring the stability of the process design level. The casting defects are predicted by solidification simulation and the casting process is optimized to ensure the excellent quality of cast steel joints.

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