| 摘要 |
A creasing device comprises a counter-rotating male drum 2 and female drum 20,40. The male drum 2 carries a conventional creasing ring 4 with a central rib 6 flanked by shoulders 8. The female drum 20,40 comprises a central channel 30,46 aligned with the creasing rib 6 on the male drum 2; and a pair of projecting lateral ribs 26,50 on each side of the central channel 30,46 that are aligned with the shoulders 8 on the male drum 2. The lateral ribs 26,50 press a sheet 14 of the card or paper stock against the shoulders 8 of the creasing ring 4 to better define the edges of the crease and to reduce the tendency of a printed coating on the stock to crack during subsequent folding. The pair of lateral ribs 26 may be provided by a pair of inserts. Alternatively, both ribs 50 and the central channel 46 may be provided by a single insert 42. |
