Research On The Process Of Iron Mould Coated Sand For Nodular Iron Crankshaft With High Strength And Ductility

Automobile is one of the important communication tools of the current time. Engine is the core part of the vehicle, and crankshaft is the key point of engine. With the increasing of the power of the diesel engine, the crankshaft will bear the higher alternating loads. The requirement to the strength, the ductility and the reliability of the material of the crankshaft is higher and higher. The original crankshaft and the medium strength crankshaft cannot satisfy the demand.Since the cast iron crankshaft has the advantages, in the paper, we do the research on the process of iron mould coated sand for nodular iron crankshaft with high strength and ductility. The cast structure of crankshaft by the process is compact and mechanics capability better. Other more, it observably enhances the size precision and consumedly reduces exterior coarseness. The quality of the cast crankshaft improves consumedly. Consequently, based on keeping high strength of the crankshaft, research on the process of iron mould coated sand for QT880-6 crankshaft raises the ductility of nodular cast iron greatly, has make the specific elongate on rising 6 percent average.This paper presents the process of getting the qualified molten iron through melting scrap, carburant and moderate cast iron, which offers a new way for producing ductile iron. The chemical constituent was 3.6~3.9 C%,1.8~2.4 Si%,0.25~0.6 Mn%,0.3~0.7 Cu%,≦0.05 P%,≦0.03 S%。By the example of 430 crankshaft, the paper design the technology, improve workmanship for the crankshaft by iron mould coated sand. Based on the working characteristic, the paper determines the processing parameters of iron mould coated sand , which includes the crankshafts cast thickness, sand coating thickness, and thickness of metal mold. The paper offers effective processes for the defect structure in the crankshaft production. In the paper, the mechanical property of crankshaft is improved by incomplete austenitizing, and the heat treat process parameters are set up. The normalization process is to heat the crankshaft up to temperature of (860±30)℃and then get it soaked for (1.5±0.5) hour prior to mist cooling. The tempering process is to heat the crankshaft up to temperature of (600±20)℃and then get it soaked for (2.0±0.5) hour prior to air-cooling.