# Case study on solidification process and mold vibration transient of centrifugal casting furnace tube

As shown in Fig. 1, the temperature of the cast pipe and mold changes along the radial direction. It is noted that the solidus temperature TS = 1158 ° C, when the casting tube mass is 309.6kg (Fig. 1 (a)), the time for complete solidification is about 40s. The smaller the casting tube mass is, the shorter the time for complete solidification is. When the casting tube mass is 180.6kg (Fig. 1 (d)), the time for complete solidification is less than 20s.

As shown in Fig. 2, the temperature of the cast pipe and mold changes along the axis. It can be seen that the temperature near the end is slightly lower than that in the middle at the same time, whether it is the pipe or the mold, because in addition to radiating towards the radius, there are convection and radiation heat transfer along the axis.

Fig. 3 shows the variation trend of the amplitude of several nodes with time. It can be seen that the vibration of each node increases with the increase of time. This is because, in the initial state, the temperature of the mold is low, the elastic modulus is large, that is, the rigidity is large, so the vibration is relatively small at the beginning. As time goes on, the heat is gradually transferred from the internal liquid metal to the external casting mold, the mold temperature is gradually increased, the elastic modulus is decreased, and the flexibility is increased, so the vibration will increase with time.

From the results of calculation and analysis, it can be known that considering the vibration of the mold rotor, the inner surface of the casting will no longer coincide with that without considering the vibration, but will have a certain offset, resulting in the phenomenon of uneven wall thickness. When the temperature change of the system is introduced into the model, the vibration of the mold rotor will change with the temperature change, which will also lead to the change of the wall thickness of the casting with time. Fig. 4 shows the variation law of the wall thickness of the cast pipe at the center of the axis direction with time. It can be seen that on the same section, the maximum wall thickness of the cast pipe gradually increases with time, while the minimum wall thickness gradually decreases with time, that is, the difference between the maximum wall thickness and the minimum wall thickness increases with time.

Figure 5 shows the variation of the final wall thickness difference along the axis. The results are drawn in the same figure. It can be seen that the wall thickness difference of each section of the casting furnace tube is in the order of micrometer, and the thickness gain of each section is different, which is determined by the mass eccentricity of the mold itself; In addition, it is found that the four curves almost coincide with each other. It can be seen that the influence of casting pipe quality on wall thickness difference is much smaller than that of vibration.

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