| 摘要 |
PROBLEM TO BE SOLVED: To simply form a folding line with a slight error, to obtain the smooth extension of the folding line and to increase the insensitiveness of a folding line to buckling breakage. SOLUTION: A folding line BL carved in the sheet cut piece of a package, especially, a foldable box under pressure is formed as a groove like recessed place and this recessed place starts from one sheet surface 5 and is closed toward other sheet surface 4 at the position of the bottom part thereof. The bottom part of the recessed place 5 is alternately constituted of regions 8 having relatively large depth T2 and regions having relatively small depth T1 in a longitudinal direction. The regions having relatively small depth T1 are restricted by a circular arc and the radius of this circular arc is at least 1.1mm and the center point M of the curvature is positioned on the opposite side of the common line L mutually connecting the regions 8 having relatively large depth T2. |
