| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve a problem that strength of a cardboard is reduced resulting from that corrugations are damaged by a hook blade when forming a zipper of the cardboard. <P>SOLUTION: A blade is formed on only one side of two sides of a hook blade for forming a zipper of a cardboard. Further, the blade is formed on the side not parallel to the advancing direction of the zipper. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
