| 摘要 |
PROBLEM TO BE SOLVED: To provide a producing method using an insert core by which a scavenging port to be an undercut part can be formed in a metallic mold casting method of a cylinder for internal combustion engine. SOLUTION: The cylinder for internal combustion engine provided with hollow scavenging air passages 14, 15 with inner walls 18, 19 forming the scavenging ports 16, 17 for opening/closing with a piston, is produced by the metallic mold casting by using the insert core 30. The insert core 30 has a cylindrical part 32 having the outer diameter almost equal to the bore diameter of the cylinder to be obtained and projectingly arranged with scavenging port forming parts 36, 37 having the almost equal cross section dimensional shape to the above scavenging ports 16, 17, an intake port forming part 41 having almost equal cross section dimensional shape to at least the end part at the cylinder bore side in an intake port 11 and an exhaust port forming part 42 having almost equal cross section dimensional shape to at least the end part of the cylinder bore side in an exhaust port 12 toward the outer part in the diameter direction from the cylindrical part 32. COPYRIGHT: (C)2004,JPO
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