Hub support is an important supporting component of automobile suspension system. During automobile driving, it mainly bears alternating impact load, and fatigue failure is its main failure form. Therefore, the hub support has high requirements for structure, strength, plastic toughness and shock absorption performance. Its comprehensive performance is directly related to the use safety of vehicles. For a long time, QT450-10 nodular cast iron has been mostly used to manufacture automobile hub supports in China. However, with the increasing requirements for automobile performance in recent years, the traditional automobile hub support has been difficult to meet the new needs of major automobile enterprises because of its insufficient strength and short service life. Therefore, the development of nodular cast iron automobile hub support products with no loss of plastic toughness and significantly improved strength compared with QT450-10 has important application value.
In addition, due to the uneven distribution of wall thickness of nodular cast iron hub support casting, the large difference between the wall thickness of thin wall and thick wall area, and the complex structure of nodular cast iron, there are often many defects such as shrinkage cavity and porosity in actual production. If the process is improved according to the previous means of empirical analysis, it is necessary to test the mold repeatedly and modify the process parameters repeatedly. The whole modification process consumes a lot of manpower and material resources. Using ductile iron simulation software to simulate the casting process of hub support, analyze the causes of defects according to the simulation results, and then continuously optimize the ductile iron process, which will greatly shorten the mold development cycle, save a lot of time and cost, and improve the process yield.
Although there are many researches on casting simulation at home and abroad, and there are many documents on process improvement based on nodular cast iron simulation, most of them are to simulate and optimize the castings with simple structure, but the simulation and process optimization of complex and special-shaped nodular cast iron are very rare. The purpose of this paper is to optimize the process of nodular cast iron for automobile hub support by means of experiment and computer numerical simulation, and solve the shrinkage porosity and shrinkage cavity defects in the casting, so as to obtain high-quality hub support casting.
(1) The composition design and performance test of nodular cast iron were carried out
According to the composition of national standard nodular cast iron, the chemical composition of high strength and Toughness Nodular Cast iron is designed by means of alloying. The mechanical properties and microstructure of each group of materials are compared to determine the composition of nodular cast iron suitable for the production of high strength and toughness automobile hub support.
(2) Process analysis and design of nodular cast iron for automobile hub support
The structural characteristics and performance requirements of hub support casting are analyzed, and the process scheme of nodular cast iron for hub support is designed and formulated.
(3) Three dimensional modeling of nodular cast iron process for hub support
Using 3D modeling software UG / nx12 0 carry out solid modeling of the designed gating system, feeding system and sand core, and complete the assembly of the whole gating system.
(4) Numerical simulation and optimization of nodular cast iron process for hub support
Convert the drawn three-dimensional model into STL format and import it into magma numerical simulation software. Simulate the mold filling and solidification process after grid division and parameter setting. According to the simulation results, analyze the location of possible defects, judge the irrationality of process design, continuously improve the process scheme of nodular cast iron and repeat the simulation and analysis process, Determine the optimal process scheme.