Surface layer shell type preparation method capable of effectively improving small-size concave profile rising

Abstract

The invention relates to the field of shell type preparation of investment casting, in particular to a surface layer shell type preparation method capable of effectively improving a small-size concaveprofile rising. The preparation method comprises the following steps that a coating is prepared, specifically, a first coating is prepared, specifically, 1 part of silica sol, 0.5-1 part of water, 2.5-3.5 parts of an aggregate, 0.001-0.005 parts of a wetting agent in part by weight are prepared, sequentially added into a first batching barrel, and uniformly stirred to form the first coating; a second coating is prepared, specifically, 1 part of the silica sol, and 2.5-3.5 parts of the aggregate in part by weight are prepared, sequentially added into a second batching barrel, and uniformly stirred to form the second coating; a wax mold is pre-coated; and shell manufacturing is carried out. The first coating with low viscosity and low surface tension is used for pre-coating and treating thewax mold, so that a wet pre-coating layer is formed between a surface layer coating and the wax mold, the direct contact between the surface layer coating and the wax mold is avoided, the phenomenonof the bubble accumulation on the small-size concave profile of the wax mold due to the oversized surface tension of the surface layer coating can be avoided, and the rising of a casting is effectively reduced.

Description

technical field [0001] The invention relates to the field of shell mold preparation of investment precision casting, in particular to a surface shell mold preparation method which can effectively improve small-sized concave surface cast nodules. Background technique [0002] Investment casting, also known as "lost wax casting", is widely used in the production of aero-engine precision castings due to its high precision and less inclusions. With the continuous improvement of engine performance requirements, the dimensional design of some parts is more complex, which puts forward higher requirements for the precision of castings. In investment casting, the key factors affecting the molding accuracy of castings are mainly affected by the shell making process, except for the dimensional accuracy of the wax mold itself. In recent years, silica sol has been widely favored in the field of shell-making binders for investment precision casting, and has gradually replaced ethyl silic...

AI Technical Summary

Problems solved by technology

[0003] However, the surface coating prepared with silica sol as a binder, due to its high density, increases the viscosity of the coating and the surface tension increases sharply, which seriously reduces the wettability of the coating to the wax model. The surface of the mold, especially the surface of the wax mold with small concave surface, is particularly obvious; and when coating the wax mol