Squeeze casting experiment

A 1000KN hydraulic press was used to apply the external pressure of squeeze casting, and a medium frequency induction aluminum furnace was used to melt the alloy. A356 aluminum alloy is used in the casting, and its chemical composition is very low. The coating is water-based graphite, which is directly sprayed on the surface of the mold cavity. The coating is mainly used for demoulding.

The data acquisition instrument used in the experiment is the data acquisition instrument made by IMC company. The data acquisition instrument can simultaneously collect 32 channels of analog signals. Each channel can be connected to various types of thermocouples, PT100 temperature sensors, and can also collect pressure, flow, voltage and other signals. The sampling frequency in this experiment is 200Hz.

Before pouring, the A356 aluminum ingot is put into the medium frequency induction furnace for melting, and then degassing and refining are carried out on the molten aluminum. Because the high frequency magnetic field will make the melt constantly agitate when the medium frequency induction furnace is running, the melt needs to stand for a period of time after degassing and refining. At the same time, four heating rods installed on the mold are needed to preheat the mold. Usually, the mold is preheated to 210 ℃ and then kept warm, and the heating is stopped before pouring. In order to demould the mold, the coating was sprayed in the mold cavity.

After everything is ready, ladle out the melted aluminum alloy melt from the medium frequency induction aluminum furnace, insert an armored thermocouple prepared in advance into the aluminum alloy melt, measure the melt temperature, and maintain the temperature measurement before pouring. In this way, the pouring temperature can be determined at any time by real-time measuring the temperature. Take out the thermocouple before pouring, and the temperature at this time is regarded as the pouring temperature.

The high-temperature melt is poured into the mold cavity, the press is quickly started, the punch falls quickly, and the external pressure is applied to the casting, and then the press is switched to the automatic pressure maintaining mode. Due to the reason of the press itself, the pressure will be released after holding for a period of time, so the press needs to continuously carry out automatic pressure supplement.

After solidification, start the press to open the mold, and then use the ejector mechanism of the press to eject the casting. Every time the casting is taken out, the temperature of the die decreases rapidly. When the temperature displayed by each thermocouple of the temperature measurement unit is basically the same and the cooling rate is less than 2 ℃ / min, the temperature of the die changes little. The next squeeze casting experiment can be carried out. Through the real-time monitoring of the temperature measurement unit, the experiment can be started when the temperature of the die decreases to the set initial temperature of the die.

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