Smelting Process The original smelting process was carried out by adding 1.4% FeSiMg8RE18 for spheroidization, adding 1.0% FeSi75 for inoculation treatment, and adding Cu-Mo alloy to achieve QT700-2 mechanical performance standard. Its performance is shown in the table below. It can be seen from the table that the carbide in the ductile iron matrix smelted by the Cu-Mo alloy can reach 15%-25%. It can be seen that this smelting process is not conducive to the full graphitization of the casting.
The new process scheme uses a furan resin sand casting technology and a high copper-tin alloy ductile iron smelting technology. In view of the characteristics of the resin sand type, the process should consider the following problems: fast filling speed, heat dispersion, smooth punching, smooth exhaust, and high rigidity of the mold.
The determination of the gating system is based on the structural characteristics of the left and right rotation, and the type of the gating system is analyzed and determined, and the no-cast casting process is used [2], as shown in Fig. 2.
Process characteristics (1) Top injection and dispersion injection plus cold iron on the outer edge are beneficial to form a balanced solidification mode and enhance the self-retracting ability of the casting. (2) Multi-pass gates, hot spots are scattered, there are many outlet holes, and the filling speed is fast. Meet the requirements of the resin sand process. (3) The thermal stress of the casting is small. (4) The disadvantage is that it lacks strong adaptability to the quality fluctuation of molten iron metallurgy. (3) The sand box has good rigidity and the two sides are tightened with bolts. (4) The rim is provided with 15 air outlets, and the hub is provided with 15 air outlets to accelerate the exhaust.
The metallurgical quality guarantees the chemical composition of ductile iron gears using high Cu-Sn alloy ductile iron [3]. The use of electric furnace smelting and intensification of inoculation measures to ensure metallurgical quality. Implementation effect In 2002 and 2003, our company produced a total of 1986t of ductile iron gears, of which more than 95% met the mechanical performance requirements to achieve stable production.
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