SHEET FOLDING MACHINE WITH WASTE PRODUCT REMOVAL

Abstract

A machine for folding sheets receives a stream of sheets. A first folding unit is followed by a further unit. The first folding unit has at least one buckle plate and at least two folding rollers to fold the sheets. A monitoring device checks the stream for defects. A control unit activates a removal device for removing waste products when a defect is detected. The monitoring device is disposed at the entry region of the buckle plate and monitors the stream in the buckle plate. The removal device is disposed downstream of the first folding unit and upstream of the further unit. The system, which is suitable for industrial folding machines, reliably detects unusable waste products in the folding process even before production might be affected.

Claims

1. A machine for folding sheets with waste product removal, the machine comprising: a sheet feeder for generating a stream of sheets; a first folding unit and a further unit disposed along a sheet transport direction, said first folding unit having at least one buckle plate and at least two folding rollers for folding the sheets; a monitoring device disposed at an entry region of said buckle plate, said monitoring device being configured to monitor the stream of sheets in said buckle plate and to check the stream for defects; a removal device for removing waste products disposed between said first folding unit and said further unit along the sheet transport direction; and a control unit connected to said monitoring device and said removal device, said control unit being configured to activate said removal device for removing a waste product when a defect is detected.

2. The machine according to claim 1, wherein said buckle plate comprises an entry lip and said entry region is positioned in vicinity to said entry lip.

3. The machine according to claim 2, wherein said entry lip is positioned in vicinity to said two folding rollers.

4. The machine according to claim 1, wherein said monitoring device comprises an ultrasound sensor.

5. The machine according to claim 4, wherein said ultrasound sensor, in a monitoring operation, is set up to detect whether there is one sheet, two sheets, or no sheet in the buckle plate.

6. The machine according to claim 4, wherein said ultrasound sensor is configured to detect whether a single layer and a double layer of sheets occur in continuous alternation in the stream.

7. The machine according to claim 6, wherein the ultrasound sensor is configured to detect whether a further double layer of sheets occurs in the stream within a specified period of time.

8. The machine according to claim 1, wherein said monitoring device is configured to check the stream in said buckle plate for at least one defect selected from the group consisting of trailing sheets entrained by leading sheets, leading sheets entrained by trailing sheets, and misfolded sheets.

9. The machine according to claim 1, wherein said removal device is disposed on a transfer device between said first folding unit and said further unit.

10. The machine according to claim 9, wherein said removal device is a switchable removal flap.

11. The machine according to claim 1, wherein said further unit is a second folding unit.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0044] FIG. 1 is a schematic, sectional side view of an exemplary embodiment of the invention with a folding machine and waste removal;

[0045] FIGS. 2A to 2C illustrate a preferred exemplary embodiment of the invention and of the further developments.

[0046] In the figures, corresponding features have the same reference symbols. Repetitive reference symbols are left out in some instances for reasons of visibility.

DETAILED DESCRIPTION OF THE INVENTION

[0047] Referring now to the figures of the drawing in detail and first, in particular, to FIG. 1 thereof, there is shown a schematic view (sectional view) of a preferred embodiment of a machine 1 for folding sheets in accordance with the invention. The machine 1 includes a sheet feeder 2 such as a stack feeder, which generates a shingled stream 4 out of sheets 3, 3a, such as sheets of paper or cardboard, and feeds the shingled stream to a first folding unit 5. The first folding unit 5 is preferably a buckle folding unit, which may include up to 6 buckle plates, for example. At least one second unit 6, in particular a second folding unit 6, preferably likewise a buckle folding unit, may be disposed downstream of the first folding unit 5. A transfer device 7, in particular a transfer table having multiple transport rollers 8 and a hold-down element 9, is disposed between the two folding units 5, 6.

[0048] The first folding unit 5 has multiple installation points 10 (for buckle plates or sheet deflectors installable in accordance with a folding scheme) and multiple folding rollers 11. Each one of the buckle plates 12, 13 creates a respective fold in the sheet 3. Every buckle plate 12, 13 has an adjustable folding stop 14 for adjusting the desired folding length. The sheet deflectors 17 merely deflect the sheets 3 (without folding them). Every buckle plate 12, 13 has an entry lip 15. The entry lip 15 is disposed to be close to the folding rollers 11, in particular adjacent to the folding rollers 11, and ensures that the sheet 3 enters the buckle plate 12, 13 in a trouble-free way.

[0049] The buckle plate 12 has a length 18 in the direction of the sheets entering and exiting the buckle plate; a folding stop 14 is adjustable in the direction of this length 18. The area indicated by reference numeral 16 and the dashed lines in the figure represents an entry region of the buckle plate 12. The entry region 16 is disposed to be close to the folding rollers 11, in particular adjacent to the folding rollers 11.

[0050] The machine 1 for folding sheets comprises a removal device 20, which is preferably designed as a removal flap 21 with a horizontal (pivot) axis 22. The removal flap 21 is arranged to pivot and may be pivoted back and forth between a first pivot position 23 and a second pivot position 24. The removal flap 21 preferably comprises a first surface 25 and a second surface 26, which may, for instance, be disposed at right angles relative to one another. In the first pivot position 23, all folded sheets 3b move across the first surface 25, whereas in the second pivot position 24, selected sheets 3b hit the second surface 26 and are thus removed. Thus the second surface 26 forms a removal element 27 for removing unusable products 28. Two removal rollers 29 may preferably be disposed below the removal flap 21 to assist in a secure removal of the defective sheets. They may, for instance, be driven via the last one (in the direction of transport) of the multiple transport rollers 8.

[0051] The sheets 3, 3a to be folded preferably enter the arrangement of folding rollers 11 as an under-shingled stream 4. There, they are folded as sheets 3, 3b, 3c by an interaction between the buckle plates 12 and the folding rollers 11, and subsequently travel along the transfer device 7 to the further unit 6 as folded sheets 3, 3d, i.e., not in a shingled formation.

[0052] In accordance with the invention, the machine 1 for folding sheets comprises a monitoring device 30, preferably an ultrasound sensor 31 with an emitter 32 and a receiver 33. In accordance with the invention, the monitoring device 30 is disposed at the entry region 16, preferably in the entry region 16. The monitoring device 30 may, for instance, be disposed to be close or even very close to the folding rollers 11. In the form of an ultrasound sensor 31, the monitoring device 30 may be disposed in such a way that the emitter 32 is disposed above the buckle plate 12 and the receiver is disposed below the buckle plate 12or vice versa. Alternatively, a reflective-light sensor 34 might be provided, for instance, which is preferably disposed to be perpendicular to the plane 35 of the sheet 3.

[0053] The monitoring device 30 may detect, for instance, whether there is one sheet 3, 3b, 3c or no sheet 3, 3b, 3c or whether there are two sheets 3, 3b, 3c in the entry region 16, in particular whether there is a single layer 36 of sheets 3 or a double layer 37 of sheets 3. The detected number of sheets 3, in particular their sequence in time, may then be compared to a defined number of sheets or sequence of sheets. If there is a match, the sheets 3 may be transferred to the further unit 6 as sheets 3d, i.e., the removal device remains inactive (first pivot position 23). In any other case, i.e., if there is no match, i.e., in case of a defect, the sheets 3 that have been found to be defective may be removed as sheets 3e, i.e., as unusable products. For this purpose, the machine 1 for folding sheets comprises a control unit 40, which is connected to the monitoring device 30 in such a way that the control unit 40 actuates, i.e., pivots, the removal device 20 in a case-by-case way.

[0054] FIGS. 2A to 2C illustrate respective details of FIG. 1 in the region of the folding rollers 11 and of the buckle plates 12, 13. The detail views illustrate various states.

[0055] FIG. 2A illustrates a first state where none of the sheets 3b or 3c are entrained by the respective other sheet. The trailing edge of the leading sheet 3b is guided around one of the folding rollers 11 and subsequently enters the further buckle plate 13. The leading edge of the trailing sheet 3c enters the entry region 16, i.e., the buckle plate 12. In this state, folded products without any defects are produced. In this process, the monitoring device 30 checks the entry region 16 of the buckle plate 12, i.e., a sheet 3 in a plane 35. The monitoring device detects a defect-free production of folded products and therefore does not activate the removal device. In FIGS. 2B and 2C, this is different.

[0056] FIG. 2B illustrates a second state in which the leading edge of the trailing sheet 3c is entrained in the exiting direction by the trailing edge of the leading sheet 3b. Thus the trailing sheet 3c does not properly enter the entry region 16, i.e., the buckle plate 12. In this state, defective folds occur. The monitoring device 30 in turn checks the entry region 16 and detects the defective production of folded products. Thus in this condition, the unusable product removal device is activated so as to remove the waste product from the product stream.

[0057] FIG. 2C illustrates a third state in which the trailing edge of the leading sheet 3b is entrained in the entry direction by the leading edge of the trailing sheet 3c. Consequently, sheet 3b does not enter the second buckle plate 13 in the desired way. In this condition, too, defective folds occur. The monitoring device 30 in turn checks the entry region 16 and detects the defective production of folded products. Thus in this case, the unusable product removal device is activated as well.

[0058] In all three states, the monitoring device 30 preferably detects whether there is one sheet or no sheet or whether there are two sheets in the entry region 16. In a particularly preferred embodiment, the monitoring device 30 uses an ultrasound sensor 31 with an emitter 32 and a receiver 33. The detected number of sheets in the entry region 16 may be compared to a target value as an actual value. The target value may be defined in accordance with the ongoing production of folds as a succession of changing values (sheet number/single layer 36 or double layer 37 of sheets).

[0059] The entrainment may be caused by the following: In the folding operation, once the fold has successfully been completed, the leading sheet 3b exits the buckle plate 12. At the same time, the trailing sheet 3c enters the buckle plate 12. The leading edge of the trailing sheet meets the surface of the leading sheet. In the entry region 16 of the buckle plate, the two sheets 3b and 3c traveling in opposite directions touch and friction occurs between them along a certain path. This touching may cause defects: for instance, the trailing sheet 3c may be pulled out of the buckle plate and entrained by the leading sheet due to friction forces that are too high or due to damage to the paper.

[0060] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: [0061] 1 machine for folding sheets [0062] 2 sheet feeder [0063] 3 sheet [0064] 3a-e sheet [0065] 4 shingled stream [0066] 5 first folding unit [0067] 6 further unit, in particular second folding unit [0068] 7 transfer device, in particular transfer table [0069] 8 transport rollers [0070] 9 hold-down element [0071] 10 installation locations for buckle plates or sheet deflectors [0072] 11 folding rollers [0073] 12 buckle plate [0074] 13 further buckle plate(s) [0075] 14 folding stop [0076] 15 entry lip [0077] 16 entry region [0078] 17 sheet deflector [0079] 18 length of the buckle plate [0080] 20 removal device [0081] 21 removal flap [0082] 22 horizontal axis [0083] 23 first pivot position [0084] 24 second pivot position [0085] 25 first surface [0086] 26 second surface [0087] 27 removal element [0088] 28 unusable product [0089] 29 removal rollers [0090] 30 monitoring device [0091] 31 ultrasound sensor [0092] 32 emitter [0093] 33 receiver [0094] 34 reflective-light sensor [0095] 35 plane of the sheet [0096] 36 individual layer of sheets [0097] 37 double layer of sheets [0098] 40 control unit