Variable thermal conductivity compound mold for thin-walled aluminum alloy casting and preparation process

Abstract

The invention provides a variable thermal conductivity compound mold for thin-walled aluminum alloy casting. The variable thermal conductivity compound mold for thin-walled aluminum alloy casting is characterized in that the raw materials comprise gypsum powder and chill sand; and the chill sand mainly comprises 30-35 wt% of silica sand, 25-30 wt% of chromite sand, 20-25 wt% of ilmenite sand and 15-20 wt% of emergy. The variable thermal conductivity compound mold for thin-walled aluminum alloy casting achieves rapid heat dissipation of a fired-pattern gypsum mold, adjusts the solidifying temperature field of a casting and improves the solidifying structure of an alloy.

Description

technical field [0001] The invention relates to a variable heat conduction composite casting mold for thin-walled aluminum alloy casting and a preparation process thereof, belonging to the field of aluminum alloy investment precision casting. Background technique [0002] With the advancement of lightweight, aluminum alloy castings with thin walls and complex structures are increasingly used in aerospace, weapons, ships and other fields. Sand casting has high thermal conductivity, which can only meet the net shape of castings with a wall thickness of 5mm or more, and the dimensional accuracy can only reach CT9~CT10, which is difficult to meet the development needs of thin-walled, precise, complex, and nearly no margin castings. Investment gypsum casting shaped castings have the characteristics of low surface roughness (Ra3.2~Ra6.3), high dimensional accuracy (CT5~CT6), thin wall (0.8~3.5mm), etc. The rate is only 220W·m -2 ·K -1 , less than 1 / 3 of the resin sand mold, 1 / 5...

AI Technical Summary

Problems solved by technology

Sand casting has high thermal conductivity, which can only meet the net shape of castings with a wall thickness of 5mm or more, and the dimensional accuracy can only reach CT9~CT10, which is difficult to meet the development needs of thin-walled, precision, complex, and nearly no margin castings.

Investment gypsum casting shaped castings have the characteristics of low surface roughness (Ra3.2~Ra6.3), high dimensional accuracy (CT5~CT6), thin wall (0.8~3.5mm), etc. The rate is only 220W·m -2 ·K -1 , less than 1 / 3 of the resin sand mold, 1 / 5 of the metal mold, the cooling rate of the aluminum melt is low during solidification, the dendrites grow excessively, and many scattered hot spots cause the isolated molten pool of the casting to be effectively fed and shrink, resulting in the solidification structure Coarse, uneven performance of castings

At present, relevant research has been carried out in China on the problem that the low thermal conductivity of the investment plaster mold leads to the coarse solidification structure of the casting, mainly focusing on the temperature control methods such as water cooling, air cooling, and local heating of the casting mold, and the optimal design of the gypsum formula. A certain effect has been achieved, but the control effect on the solidification structure of the casting is limited

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