Temperature field of compacted vermicular cast iron during mold filling

The pouring conditions of vermicular cast iron pressure plate are as follows: pouring temperature 1419 ℃, pouring speed 0.55m/s, pouring time 7.5S, external temperature 25 ℃, surface heat flow condition air cooling. The temperature field of compacted vermicular cast iron during mold filling is shown in the figure. According to the analysis of the figure, the molten metal first fills the sprue through the sprue cup, then flows into the transverse sprue, inner sprue and riser under the action of gravity, and finally flows into the mold cavity from the lugs on both sides until the whole mold cavity is filled. The whole filling process takes 7.35s, which meets the requirements of the casting process. As vermicular cast iron is produced by disa vertical parting boxless extrusion molding line, and the pouring method is to inject from both sides of the top, the lower half of vermicular cast iron pressure plate is filled first and then the upper half.

When the vermicular cast iron is filled to 5.09 s, the whole mold cavity is not full, but the lower half of the vermicular cast iron pressure plate near the inner circle and the two small lugs have been cooled to about 1300 ℃; At the end of mold filling, the temperature distribution of compacted vermicular cast iron pressure plate is uneven, the maximum temperature difference is about 124 ℃, and the whole compacted vermicular cast iron is in liquid state.

During the whole filling process, the liquid metal flows into the cavity from the lugs on both sides. The whole process is fast and stable. The liquid metal fills the cavity smoothly without splashing, insufficient pouring, cold shut and insufficient pouring. When the time is 9.6 s, all parts of the compacted vermicular cast iron pressure plate successively enter the solid-liquid two-phase zone, and the solidification process begins.

In general, at the pouring temperature of 1419 ℃ and the speed of 0.55 m/s, the pouring system can fill the mold quickly, smoothly and completely. In the process of mold filling, large temperature gradient and uneven cooling temperature will lead to casting defects such as shrinkage cavity and porosity, and large residual stress will be produced in vermicular cast iron.

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