| 摘要 |
PROBLEM TO BE SOLVED: To smoothly, accurately form a slit by providing a heat resistant filament at a trough part of a corrugated sheet surface, scanning a laser beam in a direction crossing a wave of the sheet, forming a first slit line on a ridge part, and similarly forming a second slid line on the other surface. SOLUTION: A laser beam is scanned in a direction crossing a wave of a corrugated sheet S in the state that a heat resistant filament 4 is provided at a trough part of one surface of the sheet W, the ridge part is slit except only the trough part to form first slit line 1. Similarly, the filament 4 is provided at the trough part of the other surface of the sheet S, the beam is scanned in a direction crossing the wave of the sheet S, and the ridge part is slit except only the trough part to form a second slit line. This is bent and folded in a zigzag state. As a result, the slit line can be accurately formed. Since no adhesive part is provided, the overall area of the sheet S becomes an effective area. |
