SAND CASTING EQUIPMENT.

Based on many years of casting practice, combined with the existing auto parts casting situation on the market, xinyuanzhu group divides automotive iron castings into gray iron castings, ductile iron castings, vermicular graphite iron castings, ADI, and special cast iron. Casting is gray iron castings and ductile iron castings. The other three types need to be customized.
1. Automobile gray iron castings
The typical gray cast iron part in automobiles is the cylinder block. Its development direction is thin-walled and high-strength. There are two main ways to realize it:
1.1 Low carbon equivalent process: mainly by reducing the C and Si content of gray cast iron to improve the strength of cast iron.
Its main advantages are: by changing the ingredients after the furnace, it is easy to realize, and the reliability is higher; the alloy elements are not used or used less, and the cost is lower; the requirements for the pretreatment and operation of the furnace are relatively loose. Its shortcomings are also obvious: low carbon equivalent, poor casting performance, easy to cause shrinkage (loose) waste and increase casting stress; the processing performance and section uniformity of the casting are poor, and the thermal conductivity of the casting is affected.
1.2 High carbon equivalent and alloying process: It is mainly to keep the C and Si content of gray cast iron at a high level (wC>3.3%), and to increase the strength of cast iron by adding alloying elements such as chromium and copper. , Is developing in the direction of multi-element microalloying to increase strength. Its advantages are that the alloying process is relatively mature, and the effect of improving the strength is obvious; the casting performance is better, and the tendency to form shrinkage (loose) waste products is small; the processing performance and thermal conductivity of the casting are better. The disadvantage is that more alloying elements are added, and the cost of castings is not only higher, and poor processing may also affect the workability and leakage of the castings; the requirements for furnace pretreatment are relatively strict.
With the increase of engine power, the performance requirements of gray cast iron are further improved. Some cylinder blocks of engines at home and abroad have been manufactured with HT300 or even HT350. In order to meet the needs of high-speed cutting of car cylinders, the problems of high-performance and high-speed cutting of cylinder materials have been successfully solved by optimizing the melting process, materials and alloying processes.
2. Ductile iron castings
Nodular cast iron in automobiles is mainly represented by crankshafts, camshafts, middle and rear axle housings, various brackets, housings and other parts. At present, the development of forward as-cast high-strength pearlite-based ductile iron (QT700-2, QT800-2, QT800-5) and as-cast high-toughness ferritic ductile iron (QT400-18, QT400-15, QT600-10) . It is mainly obtained by optimizing the smelting process, strictly controlling the content of S, P and trace elements in the original molten iron, selecting appropriate nodulizers, inoculants, alloying elements and adding methods, and strictly following the inoculation process.
Xinyuanzhu Group has the production technology of various grades of ductile cast iron. In order to meet the needs of the middle and rear axle housings of trucks, the as-cast QT600-5 process was developed, and the as-cast QT800-2 process was developed to meet the needs of car crankshafts. For the needs of the steering knuckle, the as-cast QT400-18 and QT400-15 processes were developed and applied in production.
In recent years, silicon solid solution strengthened ferritic ductile iron has gradually attracted domestic attention. It was first developed and applied in Sweden, and became the Swedish national standard (SS140725) in 1998. It was subsequently included in the international standard (ISO1083) in 2004. Standard GB/T 1348-2009) included it in the normative appendix. Internationally, solid solution strengthened ferritic ductile iron grades QT 450-18, QT 500-14, and QT 600-10 have been released, which have been successfully applied in automobiles.
3. Vermicular graphite cast iron
Vermicular graphite cast iron has been widely used in automobile castings such as automobile exhaust pipes and high-horsepower engine cylinder heads. Using vermicular graphite cast iron to manufacture medium and high-power engine cylinder heads, on the one hand, can reduce the weight of the cylinder head through design, on the other hand, it can also improve the performance of the cylinder head and increase the power of the engine. At present, the application of vermicular graphite cast iron in high-power engine cylinder blocks is increasing. The wall thickness can be reduced, the ribs can be eliminated, and the weight can be reduced by about 25%. It has been successfully applied to the high-power engine blocks of foreign companies such as Ford and Audi. . The application of vermicular graphite cast iron is mainly restricted by the difficulty of stable control of its production process.
4. Austempered ductile iron (ADI)
Austempered ductile iron has comprehensive mechanical properties with high strength, plasticity and toughness. It can be roughly divided into two categories, namely high-strength type with strength of 1200 ~ 1600 N/mm2 and 900 ~ 1200 N/mm2, elongation About 10% high toughness type. Due to its excellent material properties, it has achieved rapid development in developed countries in Europe and America. ADI products have been successfully applied to truck chassis, engines and car crankshafts. In recent years, in the European market, ADI has more and more applications in cars, accounting for 32% of the entire ADI market. In the US market, ADI parts for heavy and light trucks account for 51% of the entire ADI market.
In the domestic automotive field, ADI parts have also been initially applied. The total weight of this series of parts is reduced from 630.62Kg to 380.66kg, and the weight reduction rate reaches 39.6%. The rear leaf spring bracket of the truck and the gear shell cover (claw) and gear shell of military vehicles have been replaced by ADI.
5. Special cast iron
With the improvement of engine performance, the heat resistance requirements of some castings such as exhaust pipes are getting higher and higher, and high silicon molybdenum ductile iron, medium silicon molybdenum vermicular iron, and high nickel ductile iron continue to appear. A domestic joint venture Deutz engine has applied high-silicon molybdenum ductile iron exhaust pipes in batches, and high-nickel ductile iron exhaust pipes have been applied in batches to some supercharged engines.