| 摘要 |
PROBLEM TO BE SOLVED: To provide a bore pin for casting a cylinder block which causes no deformation and damage due to casting pressure, can be cooled uniformly and sufficiently in the entire circumferential direction of the bore pin, is capable of casting a cylinder block without cavities on the bore portion, and can be easily manufactured and worked. SOLUTION: The bore pin is provided with an outer bore pin 10 which has a hole portion 12 at an end used as a cylinder bore forming portion, an inner bore pin 20 which is fixed in the portion 12, and a cooling liquid pipe 30 which is provided inside both the bore pins and is provided with an inner pipe 31 and an outer pipe 32. A plurality of circular grooves 13, 14, 15 and 16 are formed on the inner circumferential surface of the portion 12, and communicating grooves 25, 26 and 27 for communicating the adjacent circular grooves are provided on the outer circumferential surface of the bore pin 20. The cooling liquid from the pipe 31 is supplied to the bore pin 20, cools the molten metal in the end side through the circular and communicating grooves, and is sent back to a space between the inner and outer pipes.
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