| 摘要 |
PURPOSE:To realize a ruled line easily along which breakage is hard to develop, by a method wherein the bottom wall of the ruled line projects to one surface side of a plastic sheet and the cross-sectional shape of the ruled line is made to be thick at its central part and thinner and its both sides than at its central part. CONSTITUTION:The bottom wall of a ruled line projects to one surface side of a plastic sheet 2. The cross-sectional shape of the ruled line 1 is made to be thick at its central part 11 and thinner at its both sides 12 than at its central part. When the ruled line 1 is drawn by pinchingly pressing the plastic sheet 2 with a male mold 3 and a female mold 4, the width W of the female mold is set to be 2 - 4 times the thickness T of the plastic sheet and the clearance A between the female mold and the male mold is set to be 0.2 - 0.7 times the thickness T of the plastic sheet. Further, the male mold 3 is fitted into the female mold 4 to the depth B, which is 0.5 - 3 times the thickness of the plastic sheet. As the plastic sheet 2, rigid sheet or semirigid sheet, which is made of polyvinyl chloride, polypropylene or the like and the thickness of which is about 0.1 - 1.0mm, is employed. Thus, a plastic sheet having a ruled line 1, is obtained easily and breakage is hard to develop, is realized. |
