GB2103190A - Sheet folding apparatus - Google Patents

Abstract

Sheet folding apparatus for four- break sheet foling comprises means for transporting a sheet 1 between one or other of two rolls 2 or 3, a folding pocket 6 selectively locatable to receive sheets passed between either pair of rolls, a roll 4, for producing folds in such sheets, and adjustable guides 7, 8 for guiding the folded sheets. <IMAGE>

Description

SPECIFICATION Sheet folding apparatus The present invention relates to sheet folding apparatus, and has particular reference to a variable pocket folding mechanism for preferably four-break folding in a folding machine, in which sheets are optionally provided in the folding mechanism with International or English fourbreak fold.

In folding machines of known construction, pocket folding mechanisms are provided in most cases for forming the third and fourth fold breaks, it being possible by adjustment of sheet deflectors, i.e. by free choice of the folding pockets to be used, to produce fold breaks in any direction. Such a folding mechanism construction is described in, for example, DE-AS 1 611 395 for forming the second, third and fourth fold breaks.

This optional use of upwardly or downwardly directed folding pockets is not, however, restricted to two-sheet folders, but is generally encountered. The optional utilization of the folding pockets in the folding roller assembly chosen in the afore-mentioned example is still not adequate, however, for realizing English and International four-break folding of thick paper. For this purpose, a further folding mechanism having a folding pocket disposed to point downwards at an obtuse angle to the sheet run is required, together with all the additional cost of procurement, maintenance, storage and increased setting-up times resulting from changing over the folding mechanisms.With the folding mechanism construction described in DD-AS 1 611 395, appropriate quality of processing without additional perforation of the sheets is possible, particularly at the fourth folding mechanism, only in the case of thin paper. When the lower folding pocket is used, squeeze creases occur in paper exceeding 70 gr/m2, as after entering the feed rollers the sheet must be introduced at an acute angle into the folding pocket. In the processing of paper from 90 gr/m2 upwards, the use of a folding mechanism as described in DD-AS 1 611 395 is only possible with compromises in regard to the quality of folding, since as the folded sheet leaves the folding mechanism squeeze creases occur when the upper folding pocket is used.

There is accordingly a need for apparatus capable of producing, for example, English and International four-break folds with minimum expenditure on procurement, maintenance, storage and installation for the folding mechanism, and with avoidance of lengthy setting-up times resulting from changing over of folding mechanisms. For preference, sheets should not be fed into folding pockets at an acute angle, regardless of their scheme-imposed arrangement.

According to the present invention there is provided sheet folding apparatus comprising transport means for sheet transport along a selectable one of a first path between two rolls and a second path between two rolls, sheet feed means for feeding sheets for transport along a selected one of the paths, a sheet receiving pocket selectably positionable in association with the selected one of the paths to receive sheets transported along that path, fold roll means associated with a roll of each path to produce folds in sheets transported along the selected one of the paths and received by the pocket, and adjustable guide means positionable to guide the folded sheets.

In a preferred embodiment, for feeding the sheets to the folding pocket, two rolls pairs and their arrangement are so provided that the forming of the fold can take place, as desired, according to the requirements relating to the desired folding scheme, either downwards or upwards. The folding pocket can accordingly be used in a first or a second position and sheet defiectors can be swung in or out respectively. To form the fold, one roll of the roll pair co-operates on each occasion for the purpose of feeding the sheets, with a folding roll. An especially advantageous construction of the folding mechanism head is achieved if the two roll pairs forfeeding the sheets constitute a total of three rolls, of which one is a constituent of both roll pairs, the direction of the rolls being changeable according to the sheet run to be selected.For the optional feeding of the sheets to one of the two roll pairs, a pivotally mounted feed table may be provided.

Depending upon the position of this feed table, the sheets are fed to one of the two roll pairs present, are transported onwards till they meet the folding pocket, are folded either in the downward direction or in the upward direction by folding roll in engagement with one roll pair and, after deflection by the swung-in sheet deflector, are fed by conveying rolls to a delivery device. When the sheets are fed to the upper roll pair in the fourth folding mechanism, the folded sheets are delivered as English four-break fold, and when they are fed to the lower roll pair they are delivered as International four-break fold. In both cases the folding pocket extends at an obtuse angle with the plane of sheet run, so that forced guidance of the sheet at an acute angle is avoided. The folding mechanism of the said embodiment can therefore be used for all types of paper without restrictions.

An embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a schematic elevation of folding apparatus according to the said embodiment, the apparatus having a sheet run for the production of English four-break fold; and Fig. 2 is a view similar to Fig. 1 but with the apparatus having a sheet run for the production of International four-break fold.

Referring now the drawings, there is shown a fourth folding mechanism in which, in Fig. 1, sheets 1 can be fed to a roll pair 2 via a pivotaliy mounted feed table 5 and transported until they meet a folding pocket 6 in position I. The forming of a fold in each sheet takes place in a downward direction between a folding roll 4 and one roll of the roll pair 2 in engagement therewith. A sheet deflector 7 pivoted into an operative position, deflects the folded sheet towards conveying rolls 9 to the delivery device of the folding machine. In this position of the feed table 5 and of the folding pocket 6 in the fourth folding mechanism, the delivery is effected as English four-break fold.

In Fig. 2, the sheets 1 are fed to a roll pair 3 via the pivotally mounted feed table 5 and are transported until they meet the folding pocket 6 in position II. The forming of the fold takes place in an upward direction between the folding roll 4 and one roll of the roll pair 3 in engagement therewith. A sheet deflector 8, pivoted into an operative position, deflects the folded sheet towards conveying rolls 10 to the delivery device of the folding machine. In this position of the feed table 5 and of the folding pocket 6 changed over into position II in the fourth folding machanism, sheet delivery takes place as International fourbreak fold.

The angle a, which influences the quality of fold, i.e. the angle at which the sheet is fed to the folding pocket, is in both positions of pocket 6 greater than 900. Thus the cause of the occurrence of squeeze creases is eliminated and a universally applicable, variable folding mechanism is made available.

Claims (4)

1. Claims

   Sheet folding apparatus comprising transport means for sheet transport along a selectable one of a first path between two rolls and a second path between two rolls, sheet feed means for feeding sheets for transport along a selected one of the paths, a sheet receiving pocket selectably positionable in association with the selected one of the paths to receive sheets transported along that path, fold roll means associated with a roll of each path to produce folds in sheets transported along the selected one of the paths and received by the pocket, and adjustable guide means positionable to guide the folded sheets.
2. 2. Apparatus as claimed in claim 1, wherein the first path is defined between a first and second roll and the second path between the second and a third roll, each roll being drivable to rotate in either direction.
3. 3. Apparatus as claimed in either claim 1 or claim 2, the feed means comprising a pivotable feed table.
4. 4. Sheet folding apparatus substantially as hereinbefore described with reference to the accompanying drawings.