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 casting and use. Therefore, attention should be paid to the design of the casting structure: a) Adoption The I-shaped, slot-shaped, and box-shaped cross-sections with larger moments of inertia enhance the wall of the casting; b) the structural shape of the ribs should be appropriate; otherwise, large stress concentrations tend to occur at the edges of the ribs. In addition, the ribs should not be too large. Thick, otherwise it is easy to produce shrinkage porosity and shrinkage at the connection with the wall; c) In order to avoid the edge of the hole should be strengthened should be concentrated, such as the use of kerf reinforcement; d) Reinforced ribs are commonly used to reinforce the wheel castings The connection between the hub and the spoke plate, pair =-: between the summer heat three and the casted wall is often connected with a thickened wall with slope; e) for the thin-walled castings can be reinforced with ribs or ladder-shaped sections; avoid each other with a longer distance The large-diameter bolts fasten the aluminum alloy and magnesium alloy castings, otherwise they will produce shadows due to excessive local forces. A more reasonable casting design should use a larger number of small-diameter bolts to fasten the castings so that each bolt The fastening force 蜒:. It is not necessary to deform the softer aluminum alloy and the magnesium alloy casting, and it is also possible to reduce the pressure of the female to the boss by using a larger nut washer; g) to try to transmit the force on the casting along the axis, In order to avoid the bow from additional bending or torsional stress; one inch in thin-walled shell-shaped aluminum alloy and magnesium alloy castings, should not have a sudden change in shape; i) due to aluminum and magnesium alloy bomb r ^ 竺囔 volume is small and easy to deform, so For the aluminum alloy and magnesium alloy castings with press-fitting relationship, the casting structure must be considered when designing the castings, and the gaps produced after j deformation and multiple disassembly must be considered. Similarly, the threaded holes on aluminum alloy and magnesium alloy castings should be better than cast iron. The lengths of hatched pits in steel and steel castings are appropriately lengthened. L (length) of the brain (diameter) is used for castings of aluminum alloys, and L/d: 2.5 for castings of magnesium alloys.
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 Do not have pits that can hold water; 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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