Document inversion
For most documents the accordion folding procedure is exactly as described above. (Bookfolds require a modified form of accordion folding.) In the first phase of the standard procedure [1], the leading edge of the document is deflected downward to make contact with the folding drum. Certain document types require the document to be deflected upward in the first phase, this being necessary to present the packet with title block in the correct orientation relative to the crossfold blades. Inversion of the leading edge in this way applies to certain documents, such as those with title block trailing and long edge leading (“LEL” orientation, Chapter 4).
Other document types require another form of inversion in which the entire accordion folded packet is flipped upside down before entering the crossfold section. This procedure, again necessary for title block positioning, is accomplished at the end of the folding sequence by reversing the drum through one almost complete revolution, thus inverting the packet as it exits the accordion folder.
Section 2: The Crossfolder
Once the accordion sequence is completed, the folded packet exits to the rear of the accordion fold section and then enters the crossfold section. If no crossfold has been called for, the accordion folded packet is propelled to the rear of the crossfold section and is then ejected into the rear receiving tray. If crossfolds are required, the packet is arrested at the rear of the crossfold section by a guide fence which maintains the packet at right angles to the upper crossfold blade.
| Upper crossfold blade |
Accordion | Packet shifts |
folded packet | |
| |
Upper |
|
crossfold |
|
fold |
|
rolls |
|
[1] First crossfold action
The
When stopped by the guide fence, the accordion folded packet is driven from left to right to position it under the blade, which then makes the first crossfold by driving the packet downward into the upper crossfold fold rolls [1].
If only one crossfold is called for [2], the lower crossfold blade acts simply as a diverter, pushing the descending packet through the lower crossfold fold rolls, and then out to the crossfold receiving tray at left (viewed from the rear of the crossfold section).
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