Folding machine

Abstract

A folding machine for folding a stack of sheets, the folding machine comprising: a frame; mechanism for pre-folding a stack of sheets along a crease line into a main plane such that a booklet with a straight back is obtained; mechanism for keeping the pre-folded booklet relative to the frame; mechanism for finishing the fold; and a transport plate having a leading edge around which the stack of sheets is folded, the transport plate being movable along the mechanism for pre-folding and the mechanism for finishing the fold.

Claims

1. A folding machine for folding a stack of sheets, the folding machine comprising: a frame; means for pre-folding a stack of sheets along a crease line into a main plane such that a booklet with a straight back is obtained; means for maintaining the shape of the pre-folded booklet relative to the frame; means for finishing the fold; a transport plate having a leading edge around which the stack of sheets is folded and wherein the leading edge is abutting the fold, said transport plate being movable with its leading edge abutting the fold along the means for pre-folding and the means for finishing the fold; and two endless belts with one belt arranged on each side of the transport plate, wherein the two endless belts are guided along guide rollers for pulling the transport plate along the means for pre-folding and then along the means for finishing the fold, wherein between guide rollers the two endless belts are aligned with the means for pre-folding the stack of sheets and wherein each of the endless belts defines a plane that is perpendicular to the transport plate to position the transport plate for movement along with the stack of sheets through the means for pre-folding the stack of sheets.

2. The folding machine according to claim 1, wherein the means for finishing the fold comprise a back roller for pressing the fold between the back roller and the leading edge of the transport plate.

3. The folding machine according to claim 1, wherein the means for finishing the fold further comprise two side rollers arranged on either side of the transport plate.

4. The folding machine according to claim 1, wherein the transport plate is flexible.

5. The folding machine according to claim 1, wherein the leading edge of the transport plate comprises a bulge.

6. The folding machine according to claim 1, wherein the means for pre-folding comprise two nip rollers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic cross sectional view of a first embodiment of the folding machine according to the invention.

(2) FIG. 2 shows a schematic perspective view of a second embodiment of the folding machine according to the invention.

(3) FIG. 3 shows a schematic cross sectional view of a third embodiment of the folding machine according to the invention.

(4) FIG. 4 shows a cross section of the transport plate of a fourth embodiment according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows a schematic view of a folding machine 1 according to the invention. The folding machine 1 has two nip rollers 2, 3 for pre-folding a stack of sheets 4 around a transport plate 5. As illustrated in FIG. 1, the leading edge of the transport plate 5 abuts the fold.

(6) The transport plate 5 moves the pre-folded sheets 4 along the nip rollers 2, 3. The nip rollers 2, 3 then keep the pre-folded sheets 4 in position, such that a back roller 6 can roll over the back 7 of the pre-folded sheets 4.

(7) The transport plate 5 functions as an anvil, such that the back roller 6 can exert a large pressure to the back 7, such that a square fold is generated.

(8) Side rollers 8, 9 are arranged on either side of the transport plate 5 to provide further pressure on the pre-folded sheets 4. This pressure is counter acted by the transport plate 5, such that also the inner portion of the pre-folded sheets 4 receive sufficient pressure to be creased.

(9) FIG. 2 shows a second embodiment of a folding machine 10 according to the invention. This folding machine 10 has a set of primary rollers 11, 12, which provide a pre-folding action to a set of sheets 13 folded around a transport plate 14.

(10) The transport plate 14 is connected to two endless belts 15, 16 positioned on either side of the transport plate 14. The belts 15, 16 are guided along guide rollers 17. From inspection of FIG. 2, it can be seen that, between guide rollers 17, the belts 15, 16 are aligned with the primary rollers 11, 12 wherein the belts 15, 16 position the transport plate 14 such that the transport plate 14 can be moved along with the sheets 13 through the primary rollers 11, 12.

(11) After the pre-folding by the primary rollers 11, 12, the sheets 13 and the transport plate 14 is moved through secondary rollers 18, 19 to finish the fold in the sheets 13.

(12) FIG. 3 shows a third embodiment of a folding machine 30 according to the invention. In this embodiment, the transport plate 31 is flexible and arranged on either side to belts 32, 33.

(13) A set of sheets 34 is folded around the transport plate 31. To finish the crease in the sheets, a meandering pattern is imposed over a length x to the back of the sheets 34. This meandering pattern is caused by three rollers 35, 36, 37 and facilitated by the flexibility of the transport plate 34.

(14) FIG. 4 shows a cross section of the transport plate 40 of a fourth embodiment according to the invention.

(15) The transport plate 40 is provided on the leading edge with a bulge 41. Sheets of paper 42 are folded around the transport plate 40. When a pressure P is supplied to the sheets of the paper 42, the protruding edges of the bulge 41 concentrate the pressure, such that also the inner sheets 42 are subjected to sufficient pressure for providing the desired fold.