A kind of sequential pressurization method after crystallization and holding pressure for metal mold low-pressure casting of aluminum alloy automobile chassis casting

Abstract

The invention discloses a sequential pressure boost method after crystallization pressure maintaining and for metal-mould low-pressure casting forming of aluminum alloy automobile chassis cast parts. According to the method, an existing aluminum alloy cast part low-pressure casting process is still adopted at the stages of liquid lift, mold filling and crystallization pressure boost, and the liquid lift pressure, mold filling pressure and crystallization pressure boost pressure are controlled to be 15-21kPa, 25-35kPa and 80-100kPa correspondingly. A sequential pressure boost stage is added between the crystallization pressure maintaining stage and the pressure relief stage. According to structural characteristics of the cast parts and the solidification sequence, multiple characteristic positions are set. After the situation that the characteristic position A starts to be solidified is determined, the crystallization pressure maintaining pressure starts to be increased; after the situation that the characteristic position B starts to be solidified is determined, the pressure boost speed is increased; and after the characteristic position C starts to be solidified, the pressure boost speed continues to be increased to reach 20-40kPa / s till the crystallization pressure maintaining pressure is increased to 310-1000kPa, and then pressure maintaining is carried out till solidification of the characteristic position D is finished. By means of the sequential pressure boost method after crystallization pressure maintaining and for metal-mould low-pressure casting forming of the aluminum alloy automobile chassis cast parts, the solidification feeding effect and the mechanical property of the cast parts are remarkably improved, meanwhile the defects of molten aluminum splashing, casting fin and burrs and the like are avoided, and the requirement for a mold structure and casting-molding mold clamping force is remarkably 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 by sequentially increasing the pressure after entering the crystallization and pressure-holding stage according to the sequential solidification time 1. Sequential pressurization method after crystallization and pressure holding for metal mold low pressure casting. 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 199...

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Problems solved by technology

[0008] The purpose of the present invention is to solve the problem that it is difficult to achieve high crystallization boost pressure in low-pressure casting of aluminum alloy automobile chassis castings with complex shapes and variable cross-sections. After entering the stage of crystallization and holding pressure, the pressurization method is used for the low-pressure casting of aluminum alloy castings, which is continuously pressurized according to the solidification sequence, so as to further reduce casting defects such as shrinkage cavities and porosity, and improve the microstructure and mechanical properties of castings.

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