Die casting is widely used in automobiles, 3C products, hardware parts, and other fields due to its advantages of high efficiency, high material utilization, and high forming accuracy. Corresponding die-casting molds need to be designed for specific die-casting parts, and the shell needs to be formed using side gate die-casting molds. The design and manufacturing of side gate die-casting molds are key to ensuring the quality of aluminum alloy die-casting parts. Taking aluminum alloy shell parts as an example, this article introduces the design of die-casting molds for aluminum alloy horizontal cold chamber die-casting machines.

A process analysis was conducted on an aluminum alloy die-casting part of a certain shell, and the structural design of the die-casting mold for a horizontal cold chamber die-casting machine was introduced in detail, mainly including the selection of parting surfaces, pouring system design, side core pulling design, and demolding mechanism design. The working principle and structural characteristics of the die-casting mold were explained, providing reference for the structural design of die-casting molds for horizontal cold chamber die-casting machines.

Graphic and textual results

The shell structure is shown in Figure 1 and Figure 2. The casting requires high strength, light weight, and can work in high temperature and high humidity environments above 100 ℃. Therefore, YL102 aluminum alloy with a melting point of 650 ℃ is selected. Due to the high Si content, a metal crucible is used for the melting furnace. The casting has 2 through holes with a diameter of 6mm and blind holes with a diameter of 8mm. It has a cylindrical surface with a diameter of 56mm. The center distance between the 2 through holes with a diameter of 6mm is required to be 280-0.2mm, and the dimensional accuracy of the casting is not high. The casting has good formability and is required to have a smooth surface without any casting defects such as cracks, cold shuts, or porosity inside. The starting angle of the inner and outer surfaces is set at 1 °, and the casting wall thickness is 4mm. A rounded corner with a radius of 1mm is set at the transition between the inner and outer cylindrical surfaces; Die casting process parameters: injection specific pressure of 65MPa, filling speed of 42m/s, pouring temperature of 630 ℃, mold preheating temperature of 160 ℃, filling time of 0.1s, using sodium fluoride water as coating. According to the projection area method to calculate the clamping force, the J1110A horizontal cold chamber die-casting machine is selected for die-casting. The inner diameter of the die-casting machine's chamber is 40mm, the outer diameter is 90mm, and the injection stroke is 0-120mm.

(1) Option I: The large core of the die-casting mold is located in the core fixing plate, and the cavity and small core are located in the cavity plate. The advantage is that the ejection force of the die-casting part is small. The disadvantage is that it is difficult to ensure the symmetry between the two small holes with a diameter of 6mm on the die-casting part and the centerline of the outer circle with a diameter of 56mm and the inner hole with a diameter of 48mm; The parting surface of the die-casting mold is the lower plane (assembly reference surface) of the die-casting part, with flying edges on top, which cannot ensure the accuracy of dimensions 20mm and 16mm (see Figure 1). Obviously, the quality of the die-casting part cannot be guaranteed with this scheme.

(2) Scheme II: Part of the mold cavity and large core are placed in the mold core fixing plate, while the other part of the mold cavity and small core are placed in the mold cavity plate. The disadvantage is that it is difficult to ensure the symmetry between the center lines of the two die castings with a diameter of 6mm and the outer circle of the casting with a diameter of 56mm and the inner hole with a diameter of 48mm. The parting surface of the die casting mold is set on a plane with an outer circle, which artificially causes the outer circle of the die casting to have burrs and results in poor appearance quality of the casting.

(3) Scheme III: The die-casting model cavity and large core are located in the cavity plate, while the small core is located in the core fixing plate. The advantage is that the flying edge of the casting is not on the installation reference surface of the casting. The disadvantage is that the symmetry between the two small holes with a diameter of 6mm in the casting and the centerline of the outer circle with a diameter of 56mm and the inner hole with a diameter of 48mm has a certain impact, but the quality of the casting can be basically guaranteed; Use the flat surface of the die-casting part as the parting surface, and there are flying edges on the flat surface of the die-casting part. Due to the fact that the flying edges of the die-casting parts are obstructed by other components during assembly, it does not affect the appearance quality of the castings after assembly. This solution is more reasonable.

(4) Plan IV: The die-casting model cavity and large and small cores are all located in the moving mold. The advantage is that it can ensure the symmetry of the centerline between the casting's two small holes with a diameter of 6mm and the outer circle with a diameter of 56mm and the inner hole with a diameter of 48mm. The disadvantage is that the parting surface is set on the lower plane (assembly reference) of the die casting, and there are burrs on the assembly reference surface of the casting. This surface is the assembly reference surface and cannot have burrs, so the plan is unreasonable.
Option V: One part of the die casting mold cavity is located in the moving mold, while the other part is located in the fixed mold. All large and small cores are located in the moving mold. The advantage is that it can ensure the symmetry of the centerline between the casting's two small holes with a diameter of 6mm and the inner hole with a diameter of 48mm. The disadvantage is that it cannot ensure the symmetry between the two small holes with a diameter of 6mm in the die-casting part and the centerline of the outer circle with a diameter of 56mm in the die-casting part, and the use of the outer circle surface with a diameter of 5mm as the parting surface artificially causes burrs on the outer circle surface of the die-casting part, resulting in poor appearance quality. Based on the above analysis, option III is chosen, with the upper plane of the shell as the parting surface.

1. 4. Hexagonal socket screw 2. Limit plate 3. Wedge block 5. Sliding block 6. Diagonal guide column 7. Top wire 8. Spring 9. Side core 10. Dynamic mold core 11. Small core 12. Top rod 13. Large core 14. Gate sleeve 15. Diversion cone 16. Copper tube 17. Fixed mold seat plate 18. Fixed template 19. Dynamic template 20. Support plate 21. Push rod fixing plate 22. Push plate 23. Dynamic mold seat plate

Author of this article:
Wang Shanglin
Jiangmen Vocational and Technical College
Source of this article: "Special Casting and Nonferrous Alloys" magazine