Method for maintaining pressures and then quickly boosting pressures for metal low-pressure casting molding of aluminum alloy automobile chassis castings

Abstract

The invention discloses a method for maintaining pressures and then quickly boosting the pressures for metal low-pressure casting molding of aluminum alloy automobile chassis castings. The method includes that existing processes for low-pressure casting of aluminum alloy automobile chassis castings continue to be carried out at liquid lifting, mold filling and crystallization pressure boosting stages, and liquid lifting pressures, mold filling pressures and crystallization boosted pressures are 15-21 kPa, 25-35 kPa and 80-100 kPa under the control respectively; stages for maintaining the pressures and then quickly boosting the pressures are added between crystallization pressure maintaining stages and pressure releasing stages; a plurality of characteristic positions are set according to structure characteristics and solidification sequences of the castings; crystallization maintained pressures start to be increased and reach 150-1000 kPa after the fact that the characteristic positions A start to be solidified is determined, and the pressure boosting speeds are 10-40 kPa/s; then the castings enter pressure maintaining stages, the characteristic positions B, the characteristic positions C and the characteristic positions D are sequentially solidified, and the pressures continue to be maintained for 10-60 s after the characteristic positions D are completely solidified. The method has the advantages that solidification shrinkage supplementing effects and mechanical properties of the castings can be obviously improved, shortcomings of flashing of molten liquid, burr and flash of existing castings and the like can be overcome, and requirements on mold structures and casting mold clamping force can be obviously lowered.

Description

technical field [0001] The present invention relates to a method of manufacturing aluminum alloy automobile chassis castings by adopting a low-pressure casting process, more particularly, it is a method for preparing aluminum alloy automobile chassis castings that continues to be rapidly pressurized after entering the crystallization and pressure-holding stage according to the solidification time in sequence , Metal mold low-pressure casting forming method of rapid pressurization after holding pressure. Background technique [0002] In recent years, with the improvement of automobile lightweight requirements, the application of aluminum alloy structural parts in automobiles has become more and more extensive. Taking the chassis suspension system as an example, the application ratio of aluminum alloy front / rear steering knuckles is close to 50%, and the application ratio of aluminum alloy in swing arms and control arm parts has also reached about 30%. In 1995, the BMW 5 Seri...

AI Technical Summary

Problems solved by technology

[0008] Aiming at the problem that it is difficult to achieve high crystallization supercharging pressure in the low-pressure casting of aluminum alloy automotive chassis castings with complex shapes and variable cross-sections such as steering knuckles, control arms, and sub-frames, combined with the structural characteristics of such castings and the sequential solidification process According to the requirements, a pressure method for low-pressure casting molding of aluminum alloy casting metal molds with rapid pressurization after crystallization and pressure holding according to the solidification sequence is proposed to further reduce casting defects such as shrinkage cavities and porosity, and improve the microstructure of castings. Density and Mechanical Properties

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