At this stage, the market competition in the automobile industry is fierce, and the requirements for energy conservation, environmental protection, and production cost reduction in the automobile production link are constantly increasing. Therefore, the use of aluminum magnesium alloy structural castings has become the main trend of automobile casting production, and the relevant manufacturing technology has become the focus of research and development. The production technology of aluminum-magnesium alloy structural castings mainly includes high-pressure casting, squeeze casting and low-pressure casting. Compared with other technical forms, the production efficiency of high-pressure casting process is higher and the quality of casting products is better. Therefore, the high-pressure casting process is the main production process in the production of automobile castings at present. The development and research of this technology are mainly focused on the high-pressure casting link. Because the air entrainment is easy to occur during the casting process, Porosity may occur in the interior of automobile castings, which may affect the development of heat treatment operation.
In order to effectively solve the above problems, vacuum negative pressure suction casting process and double circuit vacuum system can be used. In the application process of vacuum negative pressure suction casting process, it is necessary to ensure that the die casting process is always in a high vacuum state. The metal liquid will pass through the mold, suction tube and pressure chamber in the vacuum state, and inhale from the furnace through the suction tube in the oxygen-free working environment. The steam generated by the release agent can be discharged from the vacuum system. The main characteristics of this technology work are mainly reflected in the following aspects:
First, before the technicians start the quantitative pouring, the whole system is in a high vacuum state, and the molten metal will not be oxidized during the pouring process;
Second, in the pouring process, the gas in the mold cavity and metal melt can be effectively discharged;
Third, there will be no heat loss during the casting process, and technicians can use lower pouring temperature for production operations.
At present, this technology has been applied to the mass production of automobile structural castings, providing advanced public support for the production of high-quality light alloy castings. The dual-circuit vacuum system can also be used for the production of automobile structural castings. This production mode can also be called structural parts production technology. By using this technology, the formation speed of the vacuum environment can be improved, a good manufacturing environment can be provided for the production of automobile structural castings, and the production quality of automobile structural castings can be effectively improved. One of the loops in the dual-circuit vacuum system is set at the upper end of the pressure chamber, The main function is to extract the air in the pressure chamber, which is started when the punch moves forward to seal the pouring opening, and closed immediately when the punch is about to seal the air extraction opening. The other circuit is set in the same way as the vacuum production process, which is mainly in line with the extraction of the air in the cavity. At present, the production technology of structural parts has been applied to the manufacturing of aluminum alloy integrated door inner panel, body longitudinal beam and other automotive castings.