Aluminum die castings have advantages of high production efficiency, low processing cost, easy realization of mechanical automation in production process, high dimensional accuracy of castings, good surface quality and good overall mechanical properties. But in process of casting, defects such as blowhole, flow marks, scratches, depressions, cracks and undercasting are easy to occur, which make appearance quality and mechanical properties of die castings decline. In order to avoid above problems in process of die casting, structural designer needs to evaluate scheme ahead of time in design of die casting structure, and make reasonable layout in design of part structure, so as to minimize defect by optimizing structure.
Aluminum alloy die castings must be moulded and integrated with die casting machine and aluminium alloy. Principle of die casting technology is to use high pressure to flow liquid metal into cavity of a precise metal die at high speed, and liquid metal is cooled and solidified into castings under pressure. Cold and hot chamber are two basic methods of die casting process. In cold chamber, liquid metal is poured into chamber by manual or automatic pouring device, then injection punch advances, and metal hydraulic pressure is put into chamber. In hot chamber die casting process, chamber is perpendicular to crucible, and liquid metal flows into chamber automatically through inlet of chamber. Die-casting punch moves downward, pushing liquid metal into cavity through gooseneck tube. After liquid metal solidifies, die-casting mould opens and takes out casting to complete the whole process of die-casting formation.
Rationality of design for die castings is related to the whole process of die casting. When designing die castings, structural characteristics of die castings and technological requirements of die casting should be fully taken into account. Defects of designed die castings in process of die casting should be minimized so as to improve quality of die castings to the greatest extent with optimum design scheme.