Explosion-Proof Centrifugal Fan Casting Process

Explosion-Proof Centrifugal Fan Casting Process

During operation, the impeller of an explosion-proof centrifugal fan rotates at high speed with the shaft. Therefore, the internal structure of the impeller casting must be uniform, free from inherent casting defects and surface imperfections. Simultaneously, the dynamic balance performance of the impeller must be ensured after processing. In the casting process design, both horizontal and vertical casting methods are employed. Specifically, when the impeller is in the water-filled state, its contour is positioned vertically. The feed coefficient is set to be reinforced. Laser tubes can be utilized to increase the height of the upper section of the explosion-proof centrifugal fan impeller or to ensure the quality of both the internal and external surfaces of the casting, thereby promoting feeding and shrinkage. During sand molding, metal molds employ Co-hardened sodium silicate sand, while cores use resin self-hardening sand to ensure proper alignment of the impeller's three cores and facilitate sand removal. Molds are costly but offer high strength, preventing sand loosening during forming. The three holes in explosion-proof centrifugal fan impellers allow easy sand removal, resulting in smooth casting surfaces. 3. Smelting, spheroidization, and inoculation processes. During smelting, a medium-frequency induction furnace adjusts and controls chemical composition. This lowers pig iron temperature and reduces impurity content. Raw material is high-quality fresh iron (Q10) with strictly tested composition. During smelting, the charge fully dissolves with rapid temperature rise. Slag is promptly removed to eliminate aluminum. Combustion losses are minimal. Aluminum and iron can be added to the alloy. Due to copper's low melting point, the composition of the melting agent is adjusted to achieve the tapping temperature, with its content serving as the basis. The tapping temperature of the melting agent added to the furnace is typically controlled between 1450–1490°C. The spheroidizing agent is a composite rare-earth magnesium spheroidizing preparation, added at 1.4–1.8% by weight of the melting agent. with particle size 3–8 mm. The inoculant is 75SiFe, added at 1.0–1.3% of the charge weight. Place freshly baked spheroidizing agent into the ladle's hole using a special dam-type ductile iron ladle, then cover with an inoculant layer (2/3 of the 75SiFe). Next, cover with palm-based inoculant to prolong the spheroidizing reaction time. The initial production rate of the explosion-proof centrifugal fan is approximately 2 weeks for the entire process. After reaction, gently tap the pig iron again and pour the remaining 75SiFe inoculant into the ladle. Discharge the pig iron. After reaction completion, rapidly stir and skim off the slag. Cover with palm-insulated inverted triangles to confirm spheroidization effect, then inject as needed. The pouring temperature must be controlled between 1390–1430°C. To achieve stable filling, do not interrupt the molten iron supply during pouring. (1) Through alloying and process control, QT600 inductor cast iron achieves performance specifications in the as-cast condition. (2) Employ horizontal casting technology with enhanced material supply to develop impeller castings meeting quality requirements. (3) Installation testing confirms that QT600 induction cast iron impellers meet original blower performance specifications and satisfy application demands across building materials, metallurgy, thermal power, coal, chemical, and other industries.