Casting of nodular cast iron crankshaft and development

1, the introduction of the crankshaft is one of the key components of automobile engine, the performance good or bad directly affect the service life of the car. Crankshaft is working under heavy load and changing bending moment and torsion moment, common failure modes for the bending fatigue fracture and journal wear and therefore requires the crankshaft material has high rigidity and fatigue strength and good wear resistance. With the development of the spheroidal graphite cast iron technology, its performance has been improved, quality and cheap ductile iron has become one of important materials to make the crankshaft. Since the invention of nodular cast iron, 1947 through the efforts of the not long time, the tensile strength increased to 600 ~ 900 mpa, approach or exceed the level of carbon steel. Compared with forging steel materials, nodular cast iron crankshaft both manufacture simple, low cost, and shock absorption, abrasion resistance and is not sensitive to surface crack forging steel materials do not have good qualities, thus ductile cast iron has the possibility instead of the crankshaft forging steel manufacturing. In the late 1950 s, domestic automobile factory take the lead in mass production of nanjing yuejin brand car ductile iron crankshaft. In the '60 s, no. 2 first become domestic carried out in accordance with the ductile iron crankshaft production process design and production of the car factory. In the 70 s and 80 s, small and medium-sized diesel engine in the rapid development of our country, because of the ductile iron manufacturing and economic advantages, most small and medium-sized diesel engine using ductile iron crankshaft, greatly promoted the application and development of the ductile iron crankshaft, appeared a batch of professional ductile iron crankshaft plant. Nearly ten years in the process of the rapid development of automobile industry, and has built a batch of modern ductile iron crankshaft production plants ( Or factory, workshop) , the ductile iron crankshaft is widely used in the domestic. Foreign ductile iron crankshaft is widely applied, as early as the 1950 s, foreign began is applied to nodular cast iron crankshaft production, such as America's first application, ford Chrysler, Swiss GF companies in the United States, France's Renault and Citroen company, such as Italy's fiat spa, Romania brasov car factory has succeeded in the production of nodular cast iron was applied to the crankshaft. In Germany, displacement under 2000 ml of ductile iron crankshaft of diesel engine (50%), displacement of gasoline engine under 1500 ml of ductile iron crankshaft accounted for 80%; In the American auto industry, ductile iron crankshaft accounted for 80%. Due to the manufacturing technology and economic advantages, the ductile iron crankshaft is widely used in the automobile industry's overall situation will not happen in the future. 2, the ductile iron crankshaft melting for ductile iron smelting, adopting cupola both at home and abroad, power frequency furnace duplex melting more. Iron liquid generally should pass desulfurization process, iron desulfurization methods are now using porous plug desulfurization method, namely the N2 gas blowing stir in CaC2 or compound desulfurizer desulfurization. Desulfurization of stability is of great significance for smelting iron crankshaft liquid, such as adopting induction furnace melting can better control the alloy composition range, stable spheroidizing, easy to guarantee the quality of molten iron. Spheroidizing is an important link in production of ductile iron crankshaft, stone