A plaster mold casting method for large complex thin-walled magnesium alloy parts

Abstract

The invention relates to a gypsum mold casting method for large complex thin-walled magnesium alloy parts. The surface of the assembled pattern is coated with in-situ paint, and an amorphous cold iron is arranged at the hot joint. It is 1.25% phenol resin, 0.4% toluenesulfonic acid, 1-1.5% boric acid, 2% bentonite, and the balance is chromite sand of 70-140 mesh. The casting is poured in the pressure regulating casting device, and the gypsum made by pouring the pattern The mold is placed at the pouring position of the pressure regulating casting machine, and the dry air or CO2 atmosphere containing 0.1%-1.0%SF6 is filled in the tank, and vacuum pouring and pressurized solidification are carried out. The pouring temperature is 710°C-750°C, and the initial filling mold The vacuum degree is -0.6~-0.8Mpa, and the solidification pressure is 0.020-0.025Mpa. By adopting the method of the invention, oxidation can be prevented, mold filling ability can be improved, shrinkage cavity and porosity inside the casting can be reduced, and magnesium alloy casting with higher density can be obtained.

Description

technical field [0001] The invention relates to a casting method, in particular to a gypsum mold casting method for a large complex thin-walled magnesium alloy piece. Background technique [0002] Sand casting is mostly used for large magnesium alloy castings, but the precision of the castings is low, and it is very difficult to produce large-sized, thin-walled and complex castings. Therefore, in recent years, many research and development workers have carried out a series of research on the application of gypsum molds in magnesium alloy casting. When casting high-magnesium-containing aluminum alloys and magnesium alloys in gypsum molds, there are many oxidized inclusions, high liquid surface tension, poor mold filling effect, and a high tendency to produce defects such as pores, inclusions, and shrinkage porosity. The main reason is that the chemical activity of magnesium is high, and its liquid temperature will have a violent exothermic reaction with gypsum. Therefore, gy...

AI Technical Summary

Problems solved by technology

Magnesium alloy has less solidification latent heat, and the thin wall may not be poured enough, especially the large flat part with thin wall is difficult to fill; the gas permeability of the gypsum mold is very poor, and it is difficult to hold the breath during the pouring process and stay in the mold; the gypsum cast magnesium alloy solidifies slowly, Prone to coarse grains, resulting in reduced mechanical properties

Images