The castings produced by die-casting technology have high dimensional accuracy, fine structure, small machining allowance, and high production efficiency, and are widely used in fields such as automobiles, home appliances, and mechanical equipment. The valve body studied in this project is an important carrier for the installation of automotive oil cylinder components. Its shape is relatively complex, and it requires high air tightness, accuracy, and mechanical properties. It also needs to be mass-produced, so it is produced using die-casting technology. By analyzing the structure and technical requirements of the valve body, two die-casting processes were designed, and numerical simulations were conducted using ProCAST software. The simulation results were analyzed and process optimization was carried out, ultimately eliminating shrinkage defects in the castings and obtaining a die-casting process that meets the technical requirements of the valve body, providing reference for the production of such parts.

Graphic and textual results

The casting is the valve body of an automotive oil cylinder component produced by a certain company. Its three-dimensional structural schematic diagram is shown in Figure 1, where the dark gray area is the machining surface, the machining allowance is 0.3mm, the contour dimensions are 115.5mm × 74.5mm × 71.9mm, the maximum wall thickness is 24.6mm, the minimum wall thickness is 2mm, the main wall thickness is 7mm, the mass is 0.36kg, the material is ADC12, and its mechanical properties are shown in Table 1. The casting requires deburring, with a mold opening angle of 1.5 ° to 3 °, a shrinkage rate of 0.5%, and no casting defects such as shrinkage holes, porosity, cracks, and cold shuts. The surface is subjected to shot blasting treatment.

The predicted results of shrinkage defects in pouring system 1 are shown in Figure 8. From Figure 8, it can be seen that shrinkage defects occurred in the thick wall area of the casting, with a shrinkage volume of 0.46cm3 (excluding the overflow groove) and a shrinkage rate of 80% to 90% at the cut surface. It can be seen that casting system 2 also produced shrinkage defects in the thick wall area of the casting, with a shrinkage volume of 0.16 cm3 and a shrinkage rate of 80% to 85% at the cut surface, which is less than casting system 1. The main reason is that the metal liquid started filling the thick wall area earlier under the conditions of casting system 1, and the temperature in the thick wall area was higher and the solidification rate was slower during solidification, making it easier to produce isolated liquid phases and shrinkage defects. Therefore, casting system 2 is superior.

Two die-casting processes were designed and numerically simulated through analysis of the valve body structure. The results showed that shrinkage defects occurred in the thick walled area of the casting, and the process of filling the thick walled area with molten metal first resulted in more shrinkage defects. The reason for the occurrence of shrinkage defects was that the solidification rate in the thick walled area of the casting was slower, and some areas were isolated due to the lack of metal liquid supplementation. By increasing the cooling system at the thick wall, the process was optimized, and the results showed that the optimized casting had no shrinkage defects and was verified in production, meeting the technical requirements.

author

Zhang Fang
Zibo Vocational College School of Mechanical and Electrical Engineering

This article comes from: "Special Casting and Nonferrous Alloys" magazine, "Die Casting Weekly" strategic partner