Combination of Test Bench Iron Floor and Motor Performance Testing

Chemical sand adhesion on the test bench iron floor may occur when high-temperature molten metal is oxidized to form metal oxides, primarily FeO. Iron oxide reacts chemically with SiO2 in the mold to form silicates, which have a low melting point and easily adhere to the casting surface, causing sand adhesion. The principle of sand adhesion formation on the test bench iron floor is as follows: when molten metal is poured into the sand mold of the test bench iron floor, it impacts the surface of the cavity, creating high pressure that forces the molten metal to penetrate gaps.

On the test bench iron floor, graphite and austenite coexist. Moreover, during the transformation process, graphite, austenite, and the liquid phase coexist until the eutectic transformation is complete. The phase involved in the eutectic transformation of gray cast iron is graphite. After graphite precipitates on the test bench iron floor, austenite precipitates between the branches of the graphite. Then, the two grow together, forming a somewhat nearly spherical crystal—a growing eutectic crystal. The interface of the eutectic crystal in contact with the liquid phase is uneven,and the graphite flakes on the test bench iron floor always protrude outside the eutectic crystal, extending into the liquid phase and maintaining a growth trend within the liquid phase.

Equipment inspection for the test bench iron floor: Before the shift, inspect and maintain the ladle used for the test bench iron floor. Check the overhead crane, along with the steel cables and hooks used. Measure the temperature, pour the molten metal, and after the stream inoculation temperature is appropriate, start the timer and proceed with pouring. During pouring, add stream inoculant. The pouring time for each mold is approximately 18 to 30 seconds. The total pouring time for the large ladle on the test bench iron floor should not exceed 10 minutes, with an interval of 10 to 15 seconds between molds. Before removing the pouring cup, observe the color of the solidified iron in the cup. When it turns dark red, remove the pouring cup. During pouring, remove the pouring cup from the mold.

Increase the compactness of the sand mold for the test bench iron floor. Since the casting structure cannot be changed, the molding process must be improved to enhance sand mold compactness. The foundry workshop uses a German molding line for production, which allows adjustable molding pressure. The relevant parameter for the upper mold molding pressure was 79 and has been increased to 100. At the same time, improving the compactness of the test bench iron floor allows for appropriate additional spraying of alcohol-based coatings on areas prone to sand adhesion. During the eutectic transformation of gray cast iron, graphite and austenite coexist, and there is a point where graphite, austenite, and the liquid phase coexist, exhibiting characteristics of eutectic transformation. That is, due to the dominant position of graphite during the transformation process, the cooperative growth of graphite and austenite is not very tight, and the interface of the eutectic crystal is uneven. Some also consider the eutectic transformation of gray cast iron to be an abnormal eutectic transformation.

Remove the pouring cup from the test bench iron floor and place it on the storage flatcar. Quickly separate the iron block inside the cup from the cup body. While the cup body is still hot, cover it with sand to prepare for the next pouring. Equipment inspection for the test bench iron floor: Before the shift, inspect the equipment required for this process, such as the shakeout machine, punch-out machine, pneumatic pick, water cooling circulation system, and infrared temperature measurement devices. Identify and resolve faults promptly. Check whether the nuts on the tracks and the punch-out machine are loose. If any are loose, tighten them. Perform shakeout and transfer of rough castings. To address the sand adhesion issue on the test bench iron floor, analyze possible causes based on workshop production conditions. Use quality analysis methods to develop targeted measures for the sand adhesion problem and validate them in production. Identify the key factors causing sand adhesion in castings, improve the production process for the test bench iron floor, and reduce the scrap rate of castings.

The number of austenite dendrites decreases. Under the same carbon equivalent conditions (increasing silicon content while correspondingly reducing carbon content), the number of primary austenite dendrites increases. Process factors such as the temperature of the original molten iron for the test bench iron floor, the duration the molten iron is maintained at high temperatures, the cooling rate after pouring, and the undercooling during solidification all affect the morphology of primary austenite. However, under the production conditions of the test bench iron floor, these parameters are often determined by various process requirements, making it difficult to control the primary austenite dendrites by altering these parameters.