| 摘要 |
PROBLEM TO BE SOLVED: To eliminate any repairing coating preventing a corrosive deterioration caused by damage of a plating layer and a resin film layer formed on both surfaces of an can lid and further enable a ca to be easily opened even by a child or an aged person in the case that a groove for the opening part is formed at the can lid composed of a steel plate having resin film layers formed on both surfaces. SOLUTION: A can lid panel formed by applying a resin coated steel plate formed with polyester resin films 7 on both surfaces of the steel plate is pressed and machined under application of a pair of dies having one of an upper die and a lower die as a curved surface die with a tip radius being 0.1 to 1.0 mm and the other die as a flat die, and then a groove 2 for an opening port is formed. A plate thickness (t) (mm) of the steel plate at the machined thinnest section 2a of the can lid panel applied with a press machining satisfies 2.5<=P<=5.0, P=t×Ts×[exp(n)/(nn)}×[2/√3×|In[1+(t-t0)/t0]|]n, where t0: a thickness of the steel plate (mm), n: a machining hard index at a region of 40 to 90% of uniform elongation, and TS: a tensile strength (kgf/mm2).
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