| 摘要 |
PURPOSE:To form a port hole with high precision, by a method wherein a cylinder sleeve is blanked to form the port hole, a part of a molten metal, by which a cylinder body is formed, is fed to the inner surface of the port hole, and the port hole is formed integrally with the cylinder body. CONSTITUTION:A cylinder sleeve 3, internally chilled in a cylinder body 2 of a cylinder 1, is blanked to form a port hole P formed with an intake air port 3a, a scavenging port 3b, and a exhaust port 3c, which are smoothly connected to a vent passage C formed with an intake air passage, a scavenging passage 2b, and an exhaust passage. In which case, a side P1 of the port hole P is extended parallel to a plane F including the axis of the cylinder and the side of the port hole, except the exhaust port 3c, has size wider than that of the vent passage C. Since, in case this constitution is left as it is, a wide recessed part E is present between the port hole P and the vent passage C as it is, a part of a molten metal, by which the cylinder body 2 is formed, is fed to the inner surface of the port hole P, and the port hole P is formed integrally with the cylinder body 2. |
