PURPOSE: To centrifugally cast two pieces of tapered pipes of the same inside diameter easily with one time of casting work by parting a casting at the place of a small diameter inside circumferential surface by the shrinkage stress developed on cooling and solidification of molten metal in a mold of which inside circumference surface becomes larger in diameter the nearer the two end sides.

CONSTITUTION: Molten metal (b) is supplied from a spout 2 into a mold 1, and while the inside circumferential surface of the molten metal is being maintained at the inside circumferential surface around the central axial center P by the centrifugal force developed by the revolution of the mold, the molten metal is cooled to solidify. Since a mold coating material (a) is packed in the groove 6 in a small diameter inside circumferential part, the packed part assumes a locally heat insulated state, and is therefore slower in the rate of solidification than that in the thin-walled molten metal part in contact with the small diameter inside circumferential surface part so that the casting is parted at the place of the small diameter inside circumferential part by the shrinkage stress developed on cooling and solidifying of the molten metal. After the cooling and solidifying, the casting is pulled to both sides, thus two pieces of tapered pipes of the same shape are produced simultaneously with one time of casting work by using one piece of the mold 1.