ã€China Aluminum Network】 When designing the structure of aluminum alloy and magnesium alloy castings, the following matters should also be generally noted:
1 Because of the low melting point of aluminum alloy and magnesium alloy, a variety of casting methods can be used to produce aluminum alloy and magnesium alloy castings. Therefore, when designing their structures, the casting method used for the casting should first be considered in order to take into account the corresponding structural manufacturability.
2 Aluminum alloy and magnesium alloy castings should adopt thin-walled structures as much as possible to achieve uniform wall thickness. This is beneficial to prevent shrinkage shrinkage and shrinkage and increase the strength of the casting metal. However, for the uneven thickness of the wall, it is necessary to set up aluminum alloy and magnesium alloy castings for feeder feeding, and it is also possible to use thickening of certain parts to realize solidification in order to provide favorable feeding and ensure quality.
8 Aluminum alloys and magnesium alloys are easily oxidized and inhaled, and the density is low (2/3 to 3/4 smaller than cast steel and cast iron), which makes the metal liquid static pressure small and difficult to exhaust. Therefore, aluminum alloys and magnesium alloy castings are prone to generate pores and oxidized slags, which reduce the mechanical properties and airtightness. In the design of casting structures, large horizontal planes should be avoided, the transition should be smooth, and no turbulence of molten metal should be caused. '
4 Because of the low melting point of aluminum alloy and magnesium alloy, for the castings with certain airtightness requirements, special care should be taken when designing the casting structure to avoid the use of core support to fix the core, otherwise the core support and the casting body do not fuse, Oil leak.
5 As the aluminum alloy and magnesium alloy wire shrink more, the elastic modulus is lower, and the local stress concentration is sensitive, so it is easy to produce deformation and crack in the casting and use. Therefore, attention should be paid to the design of the casting structure.
a) Using I-shaped, slotted and box-shaped cross-sections with larger moments of inertia to enhance the casting wall;
b) The structural shape of the reinforcing ribs should be appropriate, otherwise, a large stress concentration is likely to occur at the edges of the ribs. In addition, the ribs should not be too thick, otherwise shrinkage holes can easily occur at the junction with the wall.
c) In order to avoid the edge of the hole should be built should be strengthened, such as the use of flange reinforcement;
d) Reinforcement ribs are often used for wheel castings to strengthen the connection between the hub and the web. For =-: thicker wall connections with slopes are often used between the heat 3 and the cast wall;
e) Thin-walled castings can be reinforced with ribs or stepped sections; large diameter bolts that are far away from each other are not required to fasten aluminum alloys and magnesium alloy castings, otherwise they will produce shadows due to excessive local forces. Reasonable The casting design should use a large number of small-diameter bolts to fasten the castings so that the fastening force of each bolt is such that it does not deform the softer aluminum alloy and the magnesium casting, and can also be used by adopting larger ones. Nut washers reduce the pressure on the female to bosses
g) try to transmit the forces on the castings along the axis so as to avoid additional bending or torsional stress in the bow; an inch of thin-walled shell-shaped aluminum alloy and magnesium alloy castings should not have abrupt shapes;
i) Since aluminum alloys and magnesium alloys have small elastic deformations, aluminum alloys and magnesium alloy castings with a press-fitting relationship must be considered when designing the casting structure, and they must be taken after j deformation and multiple disassembly. Clearance, similarly, the threaded holes in aluminum alloy and magnesium alloy castings should be longer than those in cast iron and cast steel. For aluminum alloy castings, take L (length) of the brain (diameter)-2 for magnesium alloy castings. Take L/d:2.5.
6 Magnesium alloys have higher compressive strength than tensile strength. Therefore, when designing magnesium alloy casting structures, asymmetrical cross-sections and their compressive stress should be used.
7 Magnesium alloys have poor corrosion resistance, and commonly used surface treatment to improve the corrosion resistance of magnesium alloy castings. In addition, attention should be paid to the structural design of castings: a) Magnesium alloy castings (such as water pump castings) that are in contact with flowing water during use Don't have pits that can hold water: In order to avoid damage to the corrosion-resistant lacquer layer, there should be no sharp corners on the casting.
8 should pay attention to the use of bimetal casting, insert casting and other methods to solve the aluminum alloy and magnesium alloy casting structural design problems.
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