| 摘要 |
PURPOSE:To improve the easiness of opening a score part of can cap and the resistance to stress corrosion cracking thereof, by forming a slant surface of specific dimensions within a specific distance from the source, in the can cap having a ring-tab fastening part in the inside of the inner-surface score formed along the outer circumference. CONSTITUTION:In a can cap 1, having a ring tab 2 fastening part 4, for opening a can in the inside of an inner-surface score 5 formed along the outer circumferential edge; a slant surface 7 is provided from a position Ls <=20 times the sheet thickness away from a ring tab 2 fastening part 4 and the score 5, and the width Lt of slant surface 7 is made to 10-40 times the sheet thickness and its depth Ld is made to 2-20 times the sheet thickness on condition that Ls<=Lt, Ld<=Lt/2<1/2>. When the can is opened by pulling up the tab 2, a tensile stress acts effectively on the processed part of score 5 to produce easily a crack and reduce a can opening force. Further, a compressive stress acts on the end part of score 5 by the vacuum in the pan produced during its storage, and a stress corrosion cracking is hardly produced. |
