GB823837A - Improvements in or relating to the manufacture of cast members adapted to form parts of combustion chambers - Google Patents

Abstract

823,837. Casting composite articles. GENERAL MOTORS CORPORATION. March 18, 1958 [April 2, 1957], No. 8652/58. Class 83 (1). [Also in Group XXVII] A cast member forming part of a combustion chamber, e.g. the cylinder head 18 of a Diesel engine, has non-fusibly cast therein at least one insert 34, 40 of sheet material which extends through, and substantially normal to the surface of, a layer of said member subject, during operation, to severe cyclic temperature changes, said insert or inserts being such as to effect the formation of stress-relieving grooves 37 in said layer adjacent each insert. Under operating conditions, the initial expansive compression imposed on the surface layer of the part stresses this layer beyond its compressive yield point for the temperatures involved, and effects the formation of grooves immediately adjacent to and including the opposite sides of each insert. The inserts are so located that these grooves serve to accommodate and isolate subsequent expansion and contraction of the surface layer from the adjacent critical areas, e.g. intermediate and adjacent the valve ports 24 and injector nozzle opening 26. The units are of a material, or coated with a material, which will prevent fusion with the melt during casting, e.g. high-melting-point metal or ceramic, asbestos, or metal coated with an oxide, ceramic or metallic material, such as rolled sheet steel coated with an iron-aluminium compound. The inserts have a corrugated portion normal to and intersecting the surface layer of the combustion chamber, the corrugations lying parallel to said surface layer. In a casting method, the inserts are mounted in grooves 56, Fig. 8, in the mould by moulding-paste 60, the cast head being subsequently machined, Fig. 10, to the finished head surface.