EP1976789B1 - Apparatus for decelerating sheets to be stacked, especially paper or cardboard sheets - Google Patents

Description

The invention relates to a device for braking sheets to be deposited on a stack, in particular paper or cardboard sheets, and a machine for cross-cutting webs of material containing a braking device for the sheets produced by cross-cutting.

Known manner make cross-cutting machines from a web, in particular a paper or board web, by cross-cutting single sheets ago, which are then stored on stacks. At high operating speeds, it is necessary to decelerate the individual sheets transported from conveyor belts to the stack area prior to depositing so as not to interfere with stacking.

From the WO 91/08974 a device of the generic type is known in which the braking device has on both sides of the transport plane of the arcs arranged clamping elements with circumferential clamping zones, wherein the clamping zones at least one side during circulation time to reach the inlet plane of the sheets, so that an arc between two clamping zones can be clamped , The clamping elements are driven by a non-uniform rotary drive so that the clamping zones when applied to the sheets have the inlet velocity of the sheets. Subsequently, the speed of the clamping zones is reduced to the desired discharge speed of the sheets. After releasing the clamping of the sheets and before clamping the subsequent sheets, the clamping zones are accelerated by the non-uniform drive back to the inlet speed of the sheets.

That in the WO 91/08974 described method has the advantage that it is possible to decelerate the sheets without relative speed to the Abbremselementen. This prevents unwanted marks from appearing on the sheets.

The invention has for its object to provide a generic braking device that allows sheets of high speeds of for example 400 m / min to slow down to a significantly lower deposition rate of, for example, 80 m / min safely and without markers so that a scale flow of overlapping sheets forms, which can then be stored without problems on a stack.

• Zumindest an einer Seite der Transportebene der Bögen sind über die Breite der Vorrichtung rotierend antreibbare Klemmelemente angeordnet, die auf einem Teil ihres Umfanges Klemmzonen aufweisen, die beim Umlauf zeitweise bis in die Einlaufebene der Bögen reichen,
• auf der entgegengesetzten Seite der Transportebene der Bögen ist ein rotierendes Gegenelement angeordnet, so dass ein Bogen zwischen den Klemmzonen und dem Gegenelement einklemmbar ist,
• die Klemmelemente sind mit einem ungleichförmigen Drehantrieb verbunden, und
• in Bogenlaufrichtung mit Abstand vor den Klemmelementen ist eine Ablenkeinrichtung angeordnet, von der die Bogenhinterkanten aus der Einlaufebene nach unten abgelenkt werden.

This object is achieved according to the invention with the following features:

• At least on one side of the transport plane of the sheets, rotatably drivable clamping elements are arranged over the width of the device, which have clamping zones on a part of their circumference which at times extend as far as the entry plane of the sheets during circulation,
• on the opposite side of the transport plane of the sheets, a rotating counter-element is arranged, so that an arc between the clamping zones and the counter-element is clamped,
• the clamping elements are connected to a non-uniform rotary drive, and
• in the sheet running direction at a distance in front of the clamping elements, a deflection device is arranged, from which the sheet trailing edges are deflected from the inlet level downwards.

Due to the distance of the clamping elements of the deflector in the sheet running direction, it is possible to attack the clamping zones at the beginning of deceleration with such a large distance in front of the sheet trailing edge, that the braking operation is completed before the clamping zones are located at the sheet trailing edge. The succeeding sheet can thus move forward unchecked over its downwardly deflected sheet trailing edge during the deceleration of the previous sheet. The time during which the following sheet approaches the clamping elements above the preceding sheet is thus additionally available as a braking time for the preceding sheet. Without this distance, the braking time would be limited to the time in which a subsequent arc closes the gap to the previous arc.

Preferably, as a counter element on the other side of the transport plane also clamping elements with circumferential clamping zones are arranged, which are also driven by a non-uniform rotary drive.

The device for deflecting the sheet trailing edges down is preferably a cyclically switched suction box with suction openings on the upper side, which sucks the sheet trailing edges arranged below the inlet plane of the sheets and so moves down. In addition, the suction box retains the free end of the sheet between the clamping zones and the sheet trailing edges during braking of a sheet and thus tightened. The free bow end would otherwise tend to push forward against the braking clamping zones

As a non-uniform rotary drive for the clamping elements and the counter element, a three-phase synchronous servo motor is preferably used, which has a very low dynamic mass moment of inertia. For this, the engine is relatively long and designed with a relatively small diameter. Preferably, its length to diameter ratio is more than 4.

Preferably, the clamping zones are formed by ring-segment-shaped elements which are fastened on a hollow shaft driven by the non-uniform rotary drive. Thus, the hollow shaft has a low moment of inertia and yet a high torsional stiffness, it is preferably designed as a CFRP tube with at least 100 mm outer diameter. On the hollow shaft are preferably applied as clamping zones ring segments with kreisbogenförmigem outer diameter having an outer circumferential length of 40 mm - 100 mm. The segments are preferably made of a volume-compressible, foamed plastic material, so that the sheets can be trapped slip-free while avoiding marks.

The invention will be explained with reference to a preferred embodiment. The drawing illustrates the embodiment is simplified.

Figur 1

die Seitenansicht einer Querschneidemaschine,

Figuren 2 - 6

die Wirkungsweise der Bremsvorrichtung beim Abbremsen der Bögen und

Figur 7

in einer Seitenansicht das Wirkprinzip der Bremsvorrichtung.

It shows

FIG. 1

the side view of a cross cutting machine,

Figures 2 - 6

the operation of the braking device when braking the bows and

FIG. 7

in a side view, the operating principle of the braking device.

• Eine Längsschneideeinrichtung 2, in der die Ränder der Bahn beschnitten und gegebenenfalls die Bahn 1 in bis zu sechs Einzelbahnen aufgeteilt wird, eine Querschneideeinrichtung 3, eine Brems- und Überlappungsvorrichtung 4, von der die beim Querschneiden hergestellten Bögen übernommen und abgebremst werden, wobei sich ein Schuppenstrom bildet, sowie eine Stapeleinrichtung 5, in der die Bögen auf Stapel 6 abgelegt werden, die auf Paletten 7 liegen.

In the FIG. 1 in an overall view illustrated device is used to produce paper or cardboard sheets from a continuously fed web 1. In web / sheet travel direction (in the figures from left to right) the following components are arranged one behind the other:

• A longitudinal cutting device 2, in which the edges of the web is trimmed and, if appropriate, the web 1 is divided into up to six individual webs, a cross-cutting device 3, a braking and overlapping device 4, from which the sheets produced during cross cutting are taken and decelerated, wherein a Shingled stream forms, as well as a stacking device 5, in which the sheets are stored on stack 6, which lie on pallets 7.

The cross-cutting device 3 contains in a known manner two superimposed knife drums 8, which are each equipped with at least one transverse knife, of which the web 1 is divided into sheets 9 during the passage. If a plurality of webs 1 processed superimposed, so arise when cross-cutting sheet packages, which are then transported on. The term "sheet" used below therefore also includes sheet packages which are produced and further processed in the multi-layer operation. Behind the cross cutting device 3 are elements for taking over the web start produced at a cross section and for tightening the web in cross cutting, elements for accelerated onward transport of the arc produced at a cross section to create a gap between two sheets, and the brake and overlap device 4 are arranged , which produces a shingled stream of overlapping sheets, which is fed to the stacking device 5 with a slowed transport speed.

It begins with a high-speed upper belt conveyor 10 and an associated lower fast belt conveyor 11, each composed of individual parallel belts and driven at an increased speed relative to the speed of the web 1 entering the cross-cutter. Thus, a sheet 9 produced at the cross section is transported further at an increased speed, and in each case a gap is created between two successive sheets or sheet packages.

Behind the lower fast belt conveyor 11, the brake and overlap device 4 begins with a vacuum can be acted upon suction box 13, the upper, provided with suction openings wall parallel to some distance below the conveying plane of the sheets 9. The suction openings of the suction box 13 can be opened in cycles, so that sucked from the negative pressure respectively the trailing edges of the sheets 9 and deflected downwards. The trailing edges of the sheets are released from the fast running upper belt conveyor 10, which extends over the length of the brake and overlap device 4. The suction box 13 serves as a deflection device, from which the sheet trailing edges are deflected from the inlet level down. The suction box 13 begins a lower belt conveyor 14, which runs at the slower filing speed with which the sheets are placed on the stack 6. When braking a sheet 9, the leading edge of a subsequent, even faster moving sheet slides over its trailing edge. This results in a scale flow of overlapping sheets, which is further promoted on the lower belt conveyor 14 with the slower storage speed.

In order to be able to decelerate the sheets safely, without jamming and without markings, from a high entry speed of, for example, 400 m / min to a sufficiently low depositing speed of, for example, 80 m / min, a distance behind the suction box 13 from which the sheet trailing edges are deflected downwards are arranged, a braking device containing rotatably driven clamping elements 16 with clamping zones 17, of which the sheets 9 are clamped and braked. The clamping elements 16 with the clamping zones 17 are arranged on one side of the transport plane of the sheets (in the present example above the transport plane) across the width of the device so that the clamping zones 17 at times extend to the inlet level of the sheets 9 during circulation. On the opposite side of the transport plane of the sheets 9, a rotating counter-element 18 is arranged so that a sheet 9 or a sheet package between the clamping zones 17 and the counter-element 18 can be clamped. The clamping elements 16 are located at a distance of at least 100 mm from the inlet-side beginning of the deflection (here suction box 13) so that they can attack with a minimum distance of 100 mm from the sheet trailing edge on a sheet 9. Thus, a subsequent bend has time to slide with its leading edge over the previous when braking deceleration before it is braked itself. If necessary, the clamping elements 16 and the associated counter element 18 are limited in and against the sheet running direction (arrow 19 in FIG FIG. 2 ) adjustable, so that the distance to the deflection (suction box 13) is format dependent adjustable. In this way, the attack position of the clamping zones 17 can be adapted to the sheets 9 of the arc length.

The clamping elements 16 with the clamping zones 17 as well as the rotating counter-element 18 are each connected to a non-uniform rotary drive, which makes it possible to change the circumferential speed in one revolution. Preferably, the clamping zones 17 are formed by ring-segment-shaped elements, which are fastened on the outside on a hollow shaft driven by the non-uniform rotary drive. So that the hollow shaft a small Mass moment of inertia and yet has a high torsional stiffness, it is preferably designed as CFRP tube with at least 100 mm outer diameter. The ring segments fastened on the hollow shaft as clamping zones 17 preferably have an arcuate outer diameter with an outer circumferential length of 40 mm - 100 mm. The circumferential angle of the clamping zones 17 on the hollow shaft is preferably between 50 ° and 90 °. He corresponds to the in FIG. 7 illustrated brake angle. The ring segments are preferably made of a volume-compressible, foamed plastic material, so that the sheets can be trapped slip-free while avoiding marks. The radially measured thickness of a clamping zone 17 is preferably between 10 mm and 30 mm.

The counter-element 18 is also configured in the embodiment as a rotatable hollow shaft, the lateral surface is also occupied to avoid markings with a volume-compressible coating. Alternatively, it is possible to provide the counter element 18 identical to the upper clamping element 16 with ring segment-shaped clamping zones. This design offers the possibility to change the effective clamping length by a phase shift between the rotational movement of the upper clamping zones 17 to the lower clamping zones of the counter element.

• Durch die Klemmzonen 17 wird ein Bogen 9 oder ein Bogenpaket zusammengedrückt und gemeinsam mit dem Gegenelement 18 eingeklemmt. Beim Anlegen der Klemmzonen 17 an einen Bogen weisen diese die höhere Einlaufgeschwindigkeit V1 der Bögen auf. Anschließend wird mittels des ungleichförmigen Drehantriebes die Drehgeschwindigkeit der Klemmzonen 7 vermindert bis die niedrigere Auslaufgeschwindigkeit V2 vorliegt. Die Abbremsung erfolgt dabei schlupffrei und wird entlang einer Rampe geführt, so dass keine Schubspannungen, sondern nur noch Druckspannungen in einem Bogenpaket entstehen. Diese Druckspannungen erzeugen keine Markierungen.

As a non-uniform rotary drive for both the clamping elements 16 and the counter element 18, a three-phase synchronous servo motor is preferably used, which has a very low dynamic mass moment of inertia. The motor is therefore relatively long and has a relatively small diameter. Preferably, its length / diameter ratio is more than 4. In FIG. 7 the operating principle of the braking device 4 is shown:

• Through the clamping zones 17, a sheet 9 or a sheet package is compressed and clamped together with the counter element 18. When the clamping zones 17 are applied to a sheet, they have the higher entry speed V1 of the sheets. Subsequently, by means of the non-uniform rotary drive, the rotational speed of the clamping zones 7 is reduced until the lower outlet speed V2 is present. The deceleration takes place without slip and is guided along a ramp, so that no shear stresses, but only compressive stresses arise in a sheet package. These compressive stresses produce no marks.

• Ein mit der schnellen Einlaufgeschwindigkeit von den Bändern 10, 11 antransportierter Bogen läuft mit seiner Vorderkante in die Brems- und Überlappungsvorrichtung 4 ein (Figur 2, Figur 3). Sobald die Hinterkante des Bogens 9 sich oberhalb des Saugkastens 13 befindet, wird dieser eingeschaltet und saugt dabei die Bogenhinterkante an. Dabei löst sie sich von den schnellen Oberbändern 10 und legt sich auf die langsameren Unterbänder 14. In diesem Augenblick legen sich die Klemmzonen 17 an die Bögen 9 an und drücken diese nach unten gegen das Gegenelement 18, so dass ein Bogen oder Bogenpaket eingeklemmt wird. Beim Einklemmen weisen sowohl die Klemmzonen 17 als auch das Gegenelement 18 eine Umfangsgeschwindigkeit auf, die der hohen Einlaufgeschwindigkeit V1 entspricht. Anschließend - während die Bögen 9 geklemmt sind (Figur 5) - vermindert der Drehantrieb die Umlaufgeschwindigkeit auf die niedere Auslaufgeschwindigkeit V2. Da zu Beginn der Klemmung der Abstand der klemmenden Elemente 17, 18 von der Bogenhinterkante mehr als 100 mm beträgt, hat ein nachfolgender Bogen 9 Zeit, sich mit seiner Vorderkante über die Hinterkante des vorhergehenden Bogens 9 zu schieben, so dass ausreichend Zeit für das Abbremsen des vorhergehenden Bogens 9 besteht und zugleich eine Überlappung entsteht. Damit dies störungsfrei gelingt, ist die Ablenkeinrichtung für die Bogen (Saugkasten 13) mit ausreichendem Abstand vor den Klemmelementen 17, 18 angeordnet. Noch bevor die Vorderkante des nachfolgenden Bogens 9 die Klemmzone 17 erreicht, ist der vorhergehende Bogen 9 abgebremst und die Klemmung wurde wieder gelöst. Wie in Figur 6 dargestellt, kann nun der nachfolgende Bogen 9 sich zwischen den Klemmelementen 16, 17 hindurch schieben, während die Klemmzonen 17 wieder auf die höhere Einlaufgeschwindigkeit V1 beschleunigt werden, bevor sie sich an dem soeben eingelaufenen Bogen anlegen, um diesen abzubremsen.

The course of the braking process and the overlap of sheets 9 is in the FIGS. 2 to 6 shown:

• A sheet transported by the belts 10, 11 at the rapid entry speed enters the braking and overlapping device 4 with its front edge ( FIG. 2, FIG. 3 ). Once the trailing edge of the sheet 9 is located above the suction box 13, this is turned on and sucks in the sheet trailing edge. It releases itself from the fast upper bands 10 and lies down on the slower lower bands 14. At this moment, the clamping zones 17 apply to the sheets 9 and press them down against the counter element 18, so that a sheet or sheet package is clamped. When clamping, both the clamping zones 17 and the counter element 18 have a peripheral speed which corresponds to the high inlet speed V1. Subsequently - while the sheets 9 are clamped ( FIG. 5 ) - The rotary drive reduces the rotational speed to the lower outlet speed V2. Since at the beginning of the clamping, the distance of the clamping elements 17, 18 from the sheet trailing edge is more than 100 mm, a subsequent sheet 9 has time to slide with its leading edge over the trailing edge of the previous sheet 9, so that sufficient time for deceleration the previous sheet 9 and at the same time creates an overlap. For this to succeed without interference, the deflection of the sheet (suction box 13) with sufficient distance in front of the clamping elements 17, 18 is arranged. Even before the leading edge of the following sheet 9 reaches the clamping zone 17, the previous sheet 9 is braked and the clamping was released again. As in FIG. 6 shown, the subsequent sheet 9 can now push between the clamping elements 16, 17, while the clamping zones 17 are accelerated again to the higher inlet speed V1, before they invest in the just entered bow to decelerate this.

Claims (12)

1. Device for braking sheets (9) to be deposited on a stack (6), in particular sheets of paper or cardboard, comprising

   - clamping elements (16) which can be driven in a rotating manner and are arranged at least on one side of the transporting plane of the sheets (9), over the width of the device, said elements having clamping zones (17) which temporarily reach into the running-in plane of the sheets (9) as they rotate,

   - a rotating counter element (18) arranged on the opposite side of the transporting plane of the sheets (9), so that a sheet can be clamped in between the clamping zones (17) and the counter element (18),

   - the clamping elements (16) are connected to a non-uniform rotary drive, characterized in that

   - over part of their circumference, the clamping elements (16) have clamping zones (17) and

   - arranged at a distance upstream of the clamping elements (16) in the sheet running direction is a deflecting device (13), by which the rear edges of the sheets are deflected downwards out of the running-in plane.
2. Device according to Claim 1, characterized in that the distance between the clamping elements (16) and the deflecting device (13) is at least 100 mm.
3. Device according to Claim 1 or 2, characterized in that the distance between the clamping elements (16) and the deflecting device (13) is adjustable.
4. Device according to one of Claims 1 to 3, characterized in that the deflecting device (13) is an intermittently operable suction box with suction openings on the upper side.
5. Device according to one of Claims 1 to 4, characterized in that a three-phase synchronous servomotor is used as the non-uniform rotary drive for the clamping element (16) and/or the counter element (18).
6. Device according to Claim 5, characterized in that the three-phase synchronous servomotor has a ratio between its length and its diameter of more than 4.
7. Device according to one of Claims 1 to 6, characterized in that the clamping zones (17) in the form of segments of a ring are fastened on the outside of a hollow shaft.
8. Device according to Claim 7, characterized in that the hollow shaft is formed as a CRP tube with an outside diameter of at least 100 mm.
9. Device according to Claim 7 or 8, characterized in that the clamping zones (17) in the form of segments of a ring are produced from a volume-compressible, foamed plastics material and have a radial thickness of 10 mm - 30 mm.
10. Device according to one of Claims 7 to 9, characterized in that the clamping zones (17) have an outside diameter in the form of an arc of a circle, the angle at circumference of the clamping zones (17) on the hollow shaft being between 50° and 90°.
11. Device according to one of Claims 7 to 10, characterized in that the counter element (18) is likewise formed as a rotatable hollow shaft with a clamping zone in the form of a segment of a ring and has a non-uniform rotary drive of its own.
12. Machine for cross-cutting webs of material, in particular webs of paper or cardboard (1), comprising a cross-cutting device (3) including two cutter drums (8, 9) fitted with cross-cutters, and comprising a braking and overlapping device (4), by which the sheets (9) produced during the cross-cutting are taken over and braked, thereby forming an imbricated stream, characterized in that the braking and overlapping device (4) is formed according to one or more of Patent Claims 1 to 11.

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