Method of manufacture of articles with internal passages therein and

Abstract

In casting of hollow turbine blades problems arise with breakage or distortion of long thin cores for small diameter cooling passages, and also in maintaining cores accurately positioned for casting thin walled blades. The present invention provides a method of manufacture in which a pre-form of the blade, or other hollow article, is made in two parts and is accurately machined to define the required passage shapes or wall thicknesses in at least one of the parts, appropriate cores are made and the pre-form parts are assembled in a casting mould with the cores in position and heated to melt the preforms. Thus the cores are supported by solid material during the melting process. The melting can take place progressively in a uni-directional manner along the article so that only a narrow area of the article becomes melted at any time and the cores are supported in the melt from both ends. Thus columnar grained or single crystal articles can be made by this method. The method can also be used to produce blind-ended holes in a cast article.