| 摘要 |
PROBLEM TO BE SOLVED: To decrease the can-opening force for an easily opening can lid in a stable manner so as to improve the openability of a can. SOLUTION: To produce an easily opening can lid herein discussed, use is made of a pair of metal molds comprising a set of punch with a cutting-edge curvature of 0.5mm or less and die and a wrinkle-pressing board. The can lid 1 is given halfway shearing under condition that the biting degree of the punch should be 0.4t-0.7t (t: plate thickness) and the unilateral clearance between the punch and die should be -0.3t-0.3t. As a result, in each of the front side and back side of the can lid 1 a hole-opening notch 2a, 2b having the shape of a sharp fissure and formed with a bottom radiusρof 0.025mm or less and a depth D within a range of 0.25t-0.40t is formed.
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