Counter gravity casting of large thin wall aluminum alloy plate

Lightweight design of aerospace components is an important research direction in this field. Reducing the mass of aerospace components can not only reduce the launch cost of the vehicle, but also improve the maneuverability of the vehicle. The density of aluminum alloy is about 2.7g/cm3, with high specific strength and hardness, good comprehensive mechanical properties, and excellent conductivity, thermal conductivity and corrosion resistance. It has been widely used in various fields of national economy, such as aviation, aerospace, automobile, machinery manufacturing, shipbuilding and chemical industry. It is the most widely used non-ferrous metal structural material.

Counter gravity casting, represented by low pressure and differential pressure, is the mainstream technology for manufacturing complex thin-walled light alloy components with high metallurgical quality, which is widely used at home and abroad. The counter gravity casting equipment has the characteristics of filling mold in the counter gravity direction. The alloy liquid can be controlled to fill under the control system of liquid level pressure, solidify under high environmental pressure, the forming process is stable, the casting structure is dense and the performance is high, which significantly improves the high-quality forming ability of complex thin-walled light alloy components.

With the development of casting technology and digital computing technology, the foundry computer simulation technology, which has the advantages of high efficiency, energy saving and high reliability, has been more and more applied in the actual production of industrial and mining enterprises. At present, the more mature commercial software in the world includes German MAGMAsoft, French ProCAST, FLOW-3D, etc. Tsinghua University, Huazhong University of science and technology and other units have also made considerable progress in the field of computer simulation technology of casting in China.

With the aid of simulation technology, the influence of chill, feeding pressure and casting thickness on defect formation of aluminum alloy under counter gravity casting condition was studied, and qualified plate casting was developed.

a. The distribution of chill has an obvious effect on the formation of defects in plate casting. When there is a large gap between chill irons, shrinkage porosity is easy to form in the gap.

b. The results show that the pressurization holding value has an important influence on the formation of casting defects. When the pressurization holding value is relatively low, it can not effectively promote the feeding of defects such as shrinkage porosity. Increasing the holding pressure value can effectively reduce the defect formation tendency. For typical castings, the pressurization and holding value should be higher than a certain value.

c. When the pressure holding value is constant, the casting thickness and chill thickness have the same effect on the formation of casting defects. When the thickness of casting or chill is fixed, the tendency of forming shrinkage porosity can be effectively reduced by decreasing the thickness of chill or increasing the thickness of casting.