| 摘要 |
PROBLEM TO BE SOLVED: To obtain a core for casting which can simply reinforce a bore by coating slurry mixing complex grain composed of main grain of hard grain and auxiliary grains having good matching with molten iron into water glass on the surface of the casting core inserted in a mold and forming a bore of a cylinder, etc. SOLUTION: The reinforcing layer 11 is coated at the upper part and the lower part on the outer peripheral surface of the core 10 for forming the bore of the cylinder block. The reinforcing layer 11 is coated on the core 10 and dried with mixed material of single or various kinds of the complex grains 12 which are made to capsule with the auxiliary grains 14 of iron powder, cast iron powder, aluminum powder in the case of e.g. the cast iron of the same base metal as the cylinder block on the outer periphery of the main grain 13 using powder having <=10μm of the hard grain, e.g. alumina, WC, SiC, etc., as nucleus and further, is made to slurry with the water glass. The core for casting forming the reinforced layer 11 is set in a molding flask and the molten metal of the cast iron, etc., is poured and case. By this constitution, the reinforced layer on the bore surface can simply be formed.
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