Lost foam casting (LFC) method without roasting by using precise paraffin wax model sample and high-performance coating shell mould

Abstract

The invention discloses a lost foam casting (LFC) method without roasting by using a precise paraffin wax model sample and a high-performance coating shell mould, comprising the following steps of: (1) manufacturing the paraffin wax model sample; (2) preparing a coating; (3) coating the coating and drying; (4) dewaxing the shell mould and recovering; (5) boxing the shell mould and filling sand; (6) burning out the residual wax under a negative pressure; and (7) pouring molten metal. The LFC method without roasting by using a precise paraffin wax model sample and a high-performance coating shell mould disclosed by the invention is simple in process, low in cost, less in energy consumption, high in efficiency, and more stable in casting quality; and silica sol having the same weight with Guilin No. 5 is added in the coating on an inner layer, so that the coating property of the coating on the wax model can be obviously improved, thus ensuring finish degree, and the coating is suitable for castings with various different materials. The coating on an outer layer is low in cost after being compounded of coarse and fine quartz sand and powder, the procedure of scattering dry sand layer by layer is cancelled, and the strength, stiffness and air permeability of the coating are ensured. Test detection indicates that the coating on the inner layer or the coating on the outer layer has a normal-temperature strength of greater than 1.5 MPa and the air permeability of 1.3 cm<2>/Pa.min after being dried, has strength being greater than 1.35 MPa and air permeability being 1.5 cm<2>/Pa.min after being roasted for 10 minutes at 1000 DEG C.

Description

technical field [0001] The invention relates to lost foam casting, in particular to a lost foam casting method using a paraffin pattern and a high-performance coating shell mold without baking. Background technique [0002] Lost foam casting has been used in industrial production for more than 50 years. Foam materials have been used as castings at home and abroad. Even with the LFC method of mold foam molding, the dimensional accuracy of castings is one level lower than that of wax mold precision casting, and the surface finish Two grades lower, as for the dimensional accuracy and surface finish of a large number of FMC castings cut from foam sheets, they cannot be compared with wax castings. Moreover, the discharge of paraffin is only CO 2 +H 2 O, while the foam (EPS or STMMA and EPMMA) discharges contain a large amount of toxic gases such as benzene, toluene, ethylbenzene, and styrene, which are extremely difficult to purify. The paint needs to be dipped and sprinkled...

AI Technical Summary

Problems solved by technology

[0002] Lost foam casting has been used in industrial production for more than 50 years. Foam materials have been used as casting patterns at home and abroad. The dimensional accuracy of castings is also one level lower than that of wax mold precision casting, and the surface finish is two levels lower. As for the dimensional accuracy and surface finish of a large number of FMC method castings cut and formed by foam sheets, they cannot be compared with wax mold castings.

Moreover, the discharge of paraffin is only CO2+H2O, while the discharge of foam (EPS or STMMA and EPMMA) contains a large amount of benzene, toluene, ethylbenzene , styrene and other poisonous gases that are extremely difficult to purify, while the traditional wax pattern (investment pattern) precision casting method is cumbersome, inefficient, and Polluted by irritating and harmful gases, the shell needs to be roasted at a high temperature of 1000-1100°C after dewaxing, and the gas permeability of the shell is extremely poor.