The induction melting furnace was chosen as the melting equipment by the foundry industry due to its simple operation, low melting loss, and easy control of components. Due to the short life of the furnace ling andin the occurrence of furnace leakage incidents, production safety is seriously affected. Therefore, how to extend the life of the furnace lining and ensure the safe operation of the induction melting furnace has become a research topic in the foundry industry.

The following explains the common problems and remedies for the lining of the induction melting furnace.

Longitudinal cracks: Remedial measures: The furnace lining after knotting should be immediately baked. The furnace cannot be stopped in the previous week or half a month. It should be continuously melted and kept warm to form a thick sintered layer to resist the tension caused by cooling shrinkage. stress.

Lateral cracks: Remedy: Start with the furnace building process, keep the weight of the furnace charge consistent each time, the furnace lining density is uniform, and the ram is strong; before adding another layer of material after each layer is knotted, use a flat shovel to beat the The solid surface is about 20mm loose, so that the layers are fully engaged with each other; before the furnace is built, the charge is evenly stirred to prevent debris from falling into the charge when the furnace is built.

Furnace lining peeling: Remedy: Change the shape of the crucible mold, design it as a table body, and drill some small holes uniformly around the crucible. It is beneficial to discharge the moisture in the charge during the oven. The hole interval is 225mm and the hole diameter is 2 to 3mm. Baking time (room temperature to 400 ℃) is conducive to the drainage of moisture.

Poor sintering on the working surface: Remedial measures: change the grade of the charge, test the service life of the furnace lining, in order to avoid wrong conclusions with only one sample, two consecutive experiments can be performed (grade of the charge: F-150A, F-155A, F-165A ); Extending the oven time (such as slowing down the heating speed of the oven) can improve the erosion resistance of the working surface of the furnace.

Severe bottom wear: Remedial measures: When building the bottom of the furnace, the thickness of the tamping is 50 to 100 mm higher than the actual thickness of the bottom of the furnace. After knotting, scrape to the actual thickness to make the working surface stronger. The thickness of the secondary feed should be controlled to 80 ~ 100mm, to avoid the knot of the furnace lining is not tight; increase the cooling water flow at the bottom of the furnace, and regularly remove pipeline scale.

Part of the bottom corner is worn: Remedy: Avoid operating under low metal liquid level. If the input power is not changed, the amount of metal melted is unchanged, and the liquid level is high (70% of overcapacity). It is more economical; when the metal liquid level is too low Attention should be paid when adding materials. If large pieces of material are added and the electric furnace has high input power, the bottom will be overheated severely, which will increase the erosion.

Furnace wall side wear: Remedial measures: Keep the liquid level of the metal to be used high, so that the erosion and erosion of the furnace wall are uniform; turn on the power before pouring, so that only short-term stirring is required, and the furnace temperature is usually maintained at about 1300 ° C. The cold material is melted below 1400 ℃ to maintain a stable melting rate; during melting, the slag is picked up so that the metal quickly enters the melt flow, reducing the erosion of the furnace lining by the slag; when the crucible mold is placed, it is concentric with the induction coil to ensure the thickness of the furnace lining Even, keep the error within 3mm.

Low melting point slag: Remedy: Increase the temperature for a short time to avoid the formation of slag; often change the liquid level of the furnace to avoid the formation of slag at a fixed point.

High melting point slag: remedial measures: clean the sand and debris in the furnace before charging; use a relatively clean charge or the blast-blasted charge; the melting temperature should be controlled at about 1400 ° C.

Measures to extend the life of the furnace lining: commonly used furnace building materials are magnesia and silica sand, most of which use silica sand. Although the price of silica sand is cheap, it is easily eroded. Before the furnace is built, the charge must be manually inspected to ensure that it is clean. After manual selection, mainly to remove lumps and other impurities, and then magnetic separation, magnetic impurities must be completely removed. Because the void is inevitably formed when tamping the furnace lining dry, its size and quantity directly affect the compactness of the furnace lining. When the size and number of voids reach a certain level, it is impossible to prevent the penetration of molten steel, which leads to the occurrence of a furnace leak. Therefore, a reasonable proportion of sand particles is very important.

The factors that affect the life of the furnace body are also related to the furnace body loss during the melting process, which is mainly manifested by chemical erosion and entrainment with physical erosion. The principle is that the furnace charge reacts with the oxides in the slag to form a compound with a low melting point, which makes the furnace body thinner under the continuous washing of molten steel. After the phase melting is completed, the furnace mouth is covered with asbestos cloth to prevent the furnace body from rapidly cooling and causing cracks, and the next fusion cannot be well integrated, resulting in the phenomenon of steel penetration.

Combining years of experience in the management of induction melting furnaces, the measures taken for common problems of furnace linings have proven to be reasonable and feasible in practice; the production process, induction furnaces, furnaces, melting and maintenance of three It can effectively extend the service life of the furnace lining and reduce the number of furnace building.