How to design the most popular die casting parts

2022-09-28
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How to design die casting parts

how to design die casting parts

first, the design of die castings involves four aspects:

a, that is, the requirements of pressure casting on the shape and structure of parts; b. Process performance of die castings; c. Dimensional accuracy and surface requirements of die castings; d. Determination of parting surface of die castings; The design of die-casting parts is an important part of die-casting production technology. The following problems must be considered in the design: the selection of mold parting surface, the opening of gate, the selection of ejector position, the shrinkage of castings, the dimensional accuracy assurance of castings, the prevention of internal defects of castings, the relevant requirements of casting holes, the relevant requirements of shrinkage deformation and the size of machining allowance

second, the design principles of die castings are:

A. correctly select the materials of die castings, B. reasonably determine the dimensional accuracy of die castings; c. Try to make the wall thickness evenly distributed; d. Add process corners at each corner to avoid sharp corners

III. classification of die castings:

according to the use requirements, it can be divided into two categories. One is the parts that bear large loads or have high relative motion speed. The inspection items include size, surface quality, chemical composition and mechanical properties (tensile strength, elongation and hardness); The other is other parts. The inspection items include size, surface quality and chemical composition. When designing die castings, it should also be noted that the parts should meet the process requirements of die casting. The technology of die casting is considered from the position of parting surface, the position of top push rod, the relevant requirements of casting hole, the relevant requirements of shrinkage deformation and the size of machining allowance. Reasonable determination of the parting surface of the die-casting surface can not only simplify the structure of the die-casting mold, but also ensure the quality of the casting. Requirements for die casting parts design

IV. design requirements of die castings:

(I) shape and structure requirements of die castings: A. eliminate internal side concave; b. Avoid or reduce core pulling parts; c. Avoid core cross; A reasonable die-casting structure can not only simplify the structure of the die-casting mold, reduce and clean the manufacturing cost of the rack of the force measuring parts, but also improve the quality of the casting.

(II) wall thickness requirements of the casting design: the wall thickness of the die-casting (usually called wall thickness) is a factor of special significance in the die-casting process, and the wall thickness is closely related to the whole process specification, such as the calculation of the filling time, the selection of the inner gate speed, the calculation of the solidification time The analysis of mold temperature gradient, the role of pressure (the final specific pressure is first when Chinese chemical enterprises decide whether to conduct mergers and acquisitions), the length of mold retention time, the height of casting ejection temperature and operation efficiency; a. The thicker wall thickness of parts will significantly reduce the mechanical properties of die castings, and the compactness of thin-walled castings is good, which relatively improves the strength and pressure resistance of castings; b. The wall thickness of the casting should not be too thin, which will cause poor filling of aluminum liquid, difficult forming, poor welding of aluminum alloy, cold shuts and other defects on the surface of the casting, and bring difficulties to the die-casting process; With the increase of wall thickness, the defects such as internal pores and shrinkage cavities of die castings increase. Therefore, on the premise of ensuring that the castings have sufficient strength and stiffness, the wall thickness of castings should be reduced as much as possible and the thickness of sections should be kept uniform. In order to avoid shrinkage and other defects, the thickness of castings should be reduced (material reduction) and ribs should be added; For large-area flat plate thick wall castings, set ribs to reduce the wall thickness of the castings; According to the surface area of die castings, the reasonable wall thickness of aluminum alloy die castings is as follows: die casting surface area/mm2 wall thickness s/mm ≤ 25 1.0 ~ 3.0 > 25~100 1.5 ~ 4.5 > 100~400 2.5 ~ 5.0 > 400 3.5 ~ 6.0

(III) requirements for casting design ribs:

ribs are used to improve the strength and rigidity of parts, prevent reducing the shrinkage deformation of castings, and avoid the deformation of workpieces when they are ejected from the mold, When filling, it is used to act as an auxiliary circuit (the passage of metal flow). The thickness of the reinforcement of the die-casting part should be less than the thickness of the wall, which is generally 2/3~3/4 of the thickness at this place

(IV) fillet requirements for casting design:

all wall to wall connections on die castings, regardless of right angles, acute angles or obtuse angles, blind holes and the root of grooves, should be designed as fillets. Fillet connections should not be used only when it is expected to be determined as the parting surface. The rest of the parts must generally be fillets. The fillets should not be too large or too small. Too small die castings are prone to cracks and loose shrinkage holes, Generally, the fillet of die-casting parts is 1/2 of the wall thickness, which reduces the use of materials ≤ R ≤ wall thickness; The function of fillet is to help the flow of metal and reduce eddy current or turbulence; Avoid cracking caused by stress concentration due to the existence of rounded corners on the parts; When parts are to be electroplated or coated, the fillet can obtain a uniform coating to prevent deposition at sharp corners; It can prolong the service life of the die-casting mold, and will not cause angle collapse or cracking due to the existence of the sharp corner of the mold cavity

(V) requirements for casting slope of die casting design:

the function of slope is to reduce the friction between the casting and the mold cavity, and it is easy to take out the casting; Ensure that the casting surface is not strained; To prolong the service life of die-casting dies, aluminum alloy die castings are generally marked by highly digitalized production, networking and machine self-organization. The minimum casting inclination of the fourth industrial revolution is as follows: the minimum casting inclination of aluminum alloy die castings is 1 ° 1 ° 30 ′ 2 ° on the outer surface and the core hole on the inner surface (one side)

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