| 摘要 |
PROBLEM TO BE SOLVED: To reduce a warping back of a plastic sheet at the time of creasing, and also, easily perform a bending at the time of bending/folding by a method wherein a plurality of acute angle grooves and protruding curved surfaces are formed on a creasing surface, by using a plurality of curved surfaces and acute angle edges which are formed on a creasing blade. SOLUTION: On respective side surfaces of a creasing blade 1, first and second recess-like curved surfaces 1A, 1B to form rounded surfaces are formed, and a recess-like third curved surface 1D to form a rounded surface between the ends of respective side surfaces is formed, and a cute angle edge 1c is formed at both ends of the third curved surface 1D. By punching this creasing blade 1 through a working machine, on one surface 2a of a plastic sheet 2, a creased surface 20 is formed on the surface 2a of the plastic sheet 2, and on this surface, protruding curved surfaces 10 which correspond with respective curved surfaces 1A, 1B, 1D are formed, and at the same time, acute angle grooves 11 corresponding with respective acute angle edges 1c, are formed. Therefore, when the plastic sheet 2 is folded, the folding can be easily performed by the formed grooves. |
