| 摘要 |
A device for slowing down signatures to be folded in a chopper folder is disclosed comprising a table formed with a slot therein parallel to the direction of movement of the signatures, a headstop perpendicular to such direction, two fold rollers disposed below the slot, and a blade cooperating with the fold rollers for folding the signatures centered with respect to said slot, and further comprising a device for applying vacuum or under pressure acting upon each signature to be folded to slow it down progressively as it approaches the headstop, the slowing down force being applied to prevent bouncing of the signature off said headstop, on the one hand, and on the other hand, to produce tension in the signature until the vacuum is suddenly brought to atmosphere, the vacuum device comprising at least one series of holes disposed in accordance with the direction of movement of the signature to be folded in order to be obturated thereby one after the other until obturation of all the holes in the series of holes, which corresponds to maximum vacuum and thus maximum slow down of the signature, the vacuum device comprising a box secured under the table with the series of holes being formed in the table. |
