EP0822915B1 - Process and device for cutting across a paper web - Google Patents

Description

The invention relates to a device for cross cutting a paper web with a stationary cutting tool, which has cooperating cutting knives with one arranged in front of the cutting tool during the Operation of the device continuously driven first conveyor, by means of which the paper web between two successive cutting operations is each supplied in a predetermined length with a in the area between the first conveyor and the Cutting tool provided, driven synchronously with this Clamping device, by means of which the immediate adjacent to the cutting tool, lying in front of this Area of the paper web for the duration of the cutting process can be clamped until the passage between the Cutting knives is free again, and with one in the area between the first conveyor and the clamping device provided space in which the during the cutting process from the first conveyor continuously fed paper web section in the form of a theoretically straight versus Extend the feed direction transversely to the arched loop can.

When post-processing printed paper webs, e.g. of computer printouts, the paper web is said to be in cut individual sheets of paper with a form height e.g. can be between 3 "and 12". To for this purpose there are automatic cutting machines that are next to one Cutting tool, which is used for cross cutting the paper web is also equipped with cutting tools, which cut off the perforated edges of the paper web or can also split them lengthways. A such cutting machine that has been used in practice has proven itself excellently is in the prospectus BÖWE SYSTEC AG, D-86135 Augsburg, "BÖWE automatic cutting machine 310 ", 3/94. This automatic cutting machine processes zigzag folded, printed paper webs. It shows a cross from a resting and an up and down movable cutting knife existing Cutting tool. Before this cutting tool is arranged a first conveyor, the so-called Tractor is trained. This consists of two endless conveyor belts arranged parallel to each other, the ones with their spikes in perforation engage both edges of the paper web. This well-known The cutting machine works according to the start-stop principle. While the cutting knives are apart and the Passage between them is encouraged Tractor the paper web by one of the format height appropriate length further. Then the tractor stops and the cutting knife of the cutting tool lead the Cutting process through. Once the passage between the cutting knife is free again, the tractor started again. Although the cutting performance of this known cutting machines with about 27,000 cuts per hour, at a form height of 3 "(= 7.5 cuts / s), is already quite high, it no longer corresponds to future ones Conditions. Modern data processing systems work with laser printers at such high speed, that the well-known cutting machine is not in the The paper web printed out by the laser printer would be in a position on line, i.e. following the printer with one that corresponds to the operating speed of the printer Speed to cut up. The Working speed of the known cutting machine can no longer be increased significantly. This is system-dependent due to the start-stop principle. The paper web must be stopped before each cut and after each cut from standstill within Fractions of a second back to full conveyor speed be accelerated and this more than 30,000 x per hour. The with even greater cutting performance acceleration forces acting on the paper web are so big that the edge perforations tear out can and, if the paper web with cross perforation is provided, this on the transverse perforations tears.

From DE, A, 31 31 101 is a device for cross cutting a paper web of the type mentioned known in which one in front of the clamping device second conveyor, consisting of a continuous driven upper conveyor roller and one from below this pressable lower conveyor roller, which can be lowered from the upper conveyor roller is provided. The lowering movement of the lower one The conveyor roller is synchronized with the drive of the clamping device or the cutting knife of the kind that before a cut first the paper web in the clamping device clamped and at the same time the lower one Conveyor roller is lowered down. Because of that comes the paper web to a standstill and also the second Conveyor no longer acts on the paper web on. Since the first conveyor continuously conveyed further, the paper web is jammed and forms it between the first and the second conveyor a loop hanging freely down out. This happens during the clamping of the paper web Cross cutting the same using the cutting tool. When the cut is complete, the clamping is released and the lower conveyor roller is attached to the upper one Pressed conveyor roller of the second conveyor. Since this works at a higher conveying speed as the first conveyor, the during of the cross-cut loop drawn flat again. However, it has been shown that at higher Paper feed speeds over 0.5 m / sec. and accordingly high cutting frequency the loop formation is no longer organized and reproducible. From the chaotic conditions at Loop formation primarily results in inaccurate cuts in terms of the length of the clipped Sheets of paper outside the specified tolerances lie. In addition, the rapid succession occurs of loop formation and pulling the loop flat considerable noise pollution.

The invention is therefore based on the object Device for cross cutting a paper web to create the kind mentioned at the beginning, with which also at very high paper feed speeds and high cutting frequency a high cutting accuracy achieved and at the same time the noise pollution is significant is reduced.

This is achieved according to the invention in that between the first conveyor and the clamping device a guide plate is provided that the guide plate with a large number of openings is provided and that the space above the guide plate is enclosed by a damping hood that is arranged at a distance from the loop.

The damping hood is in combination with the Openings provided with guide plate also very high paper feed speeds and high Cutting frequencies for great cutting accuracy. Even at paper feed speeds over 0.8 m / sec. and a cutting frequency of over 10 cuts / sec. are cutting accuracies in the tenths of a millimeter range achieved with a tolerance of ± 0.3 mm. This is due to the fact that inside the damping hood defined and constant air pressure conditions are present during the loop formation Environmental influences, such as air currents, heat effects and the like. Keep away from the loop. Also be Vibrations of the loop are damped and as a result an orderly, reproducible loop formation is ensured. The arrangement is also in this context of the perforated guide plate from Importance. The guide plate ensures that the loop only ever in one direction can train, the breakthroughs being crucial Importance. Because of the breakthroughs air in during the swirling of the loop the space between the loop and the guide plate come in quickly, but especially the air escape quickly from this room again when after End the cutting process through the loop the second conveyor is pulled flat again. The invention enables the cutting performance approx. 80,000 cuts / hour at a form height of 3 ". Thanks to the high cutting performance it is possible to do the cross cutting on line afterwards perform a laser printer, which has other advantages brings with it.

Advantageous embodiments of the invention are in the Subclaims marked.

Figur 1

einen Längsschnitt der Vorrichtung zum Querschneiden einer Papierbahn,

Figur 2

einen Teillängsschnitt dieser Vorrichtung im Bereich der Schlaufenbildung in einem größeren Maßstab,

Figur 3

eine Teildraufsicht in Richtung III der Figur 2.

The invention is explained in more detail in the following, using an exemplary embodiment shown in the drawing.

Figure 1

2 shows a longitudinal section of the device for cross cutting a paper web,

Figure 2

a partial longitudinal section of this device in the area of loop formation on a larger scale,

Figure 3

a partial plan view in the direction III of Figure 2.

The device for cross cutting a paper web has according to the embodiment shown in Figures 1 and 2 a cutting tool 1 with a stationary cutting knife 2 and an up and down movable cutting knife 3 on. A first is at a distance from the cutting tool 1 Conveyor 4 is provided, which in this embodiment is designed as a so-called tractor. The tractor consists of two arranged parallel to each other Conveyor belts 5 with their spikes 6 in perforations engage on both longitudinal edges of the paper web 7. The conveyor 4 is continuously with a Peripheral speed V1 driven, e.g. the delivery speed an upstream, not shown Corresponds to the laser printer. In the area between the conveyor 4 and the cutting tool 1 is synchronous provided with this driven clamping device 8. This clamping device 8 is preferably nearby of the cutting tool 1, i.e. their distance from the cutting tool 1 is less than its distance to the conveyor 4.

Between the clamping device 8, the below is described in more detail, and the cutting tool 1 preferably immediately adjacent to this one continuously driven second conveyor 9 arranged, the conveying speed (= peripheral speed) V2 is greater than the conveying speed V1 of the first conveyor 4.

A third is expedient behind the cutting tool 1 Conveyor 10 is provided, which is also continuous is driven at a conveying speed V2, the conveyor speed V2 of the second Conveyor 9 corresponds.

The clamping device 8 comprises two jaws 11, the in the transverse direction of the paper web 7 at a distance from one another are arranged and of which only one in the drawing is shown. These jaws 11 act with a stationary pad 12 together. Each jaw 11 is at one (lower) end of a cross to the feed direction A arranged the paper web 7 movable plunger 13, whose other (upper) end carries a roller 14, which cooperates with a cam disc 15. The cam disc 15 can be driven synchronously with the cutting tool 1. For this purpose, a common Belt drive may be provided. The belt drive also drives the movable cutting knife 3. The belt drive is expediently driven continuous, but it can also be intermittent be. The drive speed n of the belt drive depends on the conveying speed V1 the first conveyor 4 adjustable so that always then a cut is made when the paper web 7 through the conveyor 4 opposite the cutting tool 1 by one of the desired format height (= form height) appropriate length was moved.

The second conveyor 9 and the third conveyor 10 appropriately each have a continuous drivable conveyor roller 20 or 21 and at least an axially parallel pressure roller 22, 23 on the under elastic prestress 24 on the conveyor roller 20 or 21 is present. The elastic bias 24 is preferred adjustable. The drive of the two conveyor rollers 20, 21 can for example by a third Engine. This third engine gives the Conveyor rollers 20, 21 a conveyor speed V2, the for example four times the conveying speed V1 of the first conveyor 4.

There is also between the first conveyor 4 and the clamping device 9 a bulging device 25 is provided, which on the paper web 7, at least at times a cross to the feed direction A directed force P exerts. If the feed direction A, as in the embodiment shown in Figures 1 and 2 the case is essentially horizontal, then the force P should be directed upwards. This has the advantage that the feed during the cutting process stored paper web section 7a after the release of the clamping device 8 also by Gravity is supported, as detailed below is described.

A guide plate can first be used to generate the force P. 26 may be provided, which compared to the Conveyor elements 5 of the first conveyor 4 and Clamping elements 11, 12 tangential to the clamping device 8 Level E-E arched transversely to feed direction A. is. In the illustrated embodiment the bulge 26a takes place upwards.

The operation of the device described so far is the following:

During the operation of the device, the first Conveyor 4 with a conveying speed V1 and the second and third conveyors 9 and 10, respectively with a higher conveyor speed V2 continuously driven. The movable cutting knife 3 can are also driven continuously so that alternately a cutting process is carried out or the passage between the cutting blades 2 and 3 is released is. While the latter is the case, too the clamping device 8 opened so that the paper web 7 by the conveyors 4 and 9 and larger ones Format heights also by the conveyor 10 in Direction A is moved on. Once the paper web compared to the cutting tool 1 by the set Format height has been pressed, the cam disc presses 15 the plunger 13 down so that the paper web between Clamping jaws 11 and stationary base 12 are clamped becomes. The conveyor rollers 20, 21 of the second conveyor 9 and the third conveyor 10 continue to rotate. The movable cutting knife 3 goes down and cuts a paper sheet 7b in the desired format height, which is immediately carried out by the third conveyor 10 is moved on. The conveyor rollers 20, 21 have one smooth steel surface and the elastic preload 24 is adjusted so that the conveyor rollers 20, 21st can continue to rotate while clamping the paper web, without damaging it.

During the paper web for the duration of the cutting process is held by the clamping device 8, conveys the first conveyor 4 continuously Paper web after. This post-conveyed paper web section is in the form of a versus the theoretical arch straight feed direction A upwards Loop 7a saved. Because of the bulging Guide plate 26 will Arching favors and ensures that the Bulge in a predetermined direction, namely after done above. During the bulge arises in the Loop 7a a tension, similar to a buckling bar. After the cutting process, the Passage between the cutting knives 2, 3 released again, then the clamping device 8 also opens, that the area 15a of the cam 15 in the Area of the roller 14 arrives. Once the clamping device 8 is opened, the second conveyor promotes 9 the end adjacent to the cutting device 1 the paper web with a conveying speed V2 further, which is higher than the conveying speed V1 the first conveyor 4. This will stored loop 7a removed. The moving on of the paper web section stored in the form of the loop 7a is also generated by the in the loop Tension favors the free end of the paper web pushes towards the cutting tool 1. The loop 7a cannot expand backwards, because paper web constantly through the first conveyor 4 is funded. In addition to that in the loop 7a built-up tension can illustrated embodiment also gravity will still take effect, which is the loop 7a pushes down and thereby the paper web in Moved towards the cutting tool 1. The second Conveyor 9 therefore only needs that in shape the loop stored small paper web section 7a to move further, this further movement by the voltage built up during the clamping and the Gravity is favored.

Holding the paper web can be done in other ways done, for example, by clamps on the edge attack the paper web. The only thing that matters is that the clamping device is synchronous with the cutting tool is driven so that the clamping device holds the paper web during the cutting process.

An important contribution to increasing the cutting performance forms that shown in Figures 2 and 3 Design of the area in which the loops are formed. It was found that at paper feed speeds about 0.8 m / s (which is about 38000 cuts per hour corresponds to a form height of 3 ") unacceptable Fluctuations in cutting accuracy occur. Around despite high feed speeds and high cutting performance adequate cutting accuracy in Tenths of a millimeter range, e.g. in the range of ± 0.3 mm, to achieve, it is appropriate to use those described below Apply measures in combination.

The guide plate 26 is curved upwards, the Bulging through an angled portion 26b of the guide plate is achieved. The guide plate 26 is still with a Plurality of openings 36, e.g. circular holes, Mistake. Through these openings 36 can during Bulge of the loop air between the loop and the guide plate can enter quickly, in particular however, the air from the space between the loop 7a and escape the guide plate 26 quickly if after Completion of the cutting process through the loop second conveyor 9 is pulled flat again. Here, the paper web 7 comes on the bend 26b to the facility. The resulting at this point Friction is achieved that the second Conveyor tension exerted on the paper web not fully up to the first conveyor 4 can reproduce.

Furthermore, seen in paper feed direction A, in the front and rear area of the guide plate 26 inclined opposite one another above it, baffles influencing the formation of the loop 37, 38 provided. These baffles 37, 38 are for Support for even loop formation. The guide plates 37, 38 ensure that the loops are always in roughly the same place and that the loop is not in the feed direction A walks forward or backward. Especially through the Baffles 37, 38 make the loop formation reproducible. In order to be able to influence the loop formation, it is also appropriate that the inclination of each baffle 37, 38 adjustable relative to the guide plate 26 is. For this purpose, the guide plates 37, 38 by one in each case transverse to the feed direction A. Axis 39, 40 pivotable and by a not shown Establishable.

Furthermore, the room is above the Guide plates 26 and above the guide plates 37, 38 enclosed by a damping hood 41. The Damping hood 41 should be at a greater distance be arranged by the loop 7a so that it is still sufficient Air space between the loop 7a and the inside of the Damping hood is present. The damping hood acts on the one hand as an air chamber, which is used for loop formation vibrations occurring at high speeds dampens and it also serves for sound insulation.

The embodiment shown in Figures 2 and 3 carry out jointly applied measures to stabilize and reproducible the Loop formation, what after the experiences with high cutting performance a requirement for a high cutting accuracy with tolerances in the tenths of a millimeter range is.

Claims (4)

1. Apparatus for cutting across a paper web (7), with a stationary cutting tool (1) which has cooperating cutter blades (2, 3), with a first feed device (4) arranged before the cutting tool and which is driven continuously during operation of the apparatus, by means of which the paper web is fed between two successive cutting operations by a predetermined length each time, with a clamping device (8) provided in the region between the first feed device (4) and the cutting tool (1) and driven synchronously with the latter, by means of which the region of the paper web (7) immediately adjoining and lying before the cutting tool (1) can be clamped fast for the duration of the cutting operation, until the passage between the cutter blades (2, 3) is free again, and with a free space (30) provided in the region between the first feed device (4) and the clamping device (8), into which the paper web section continuously fed on by the first feed device during the cutting operation can expand in the form of a loop (7a) bowed out transversely relative to the theoretical straight feed direction (A), characterized in that a guide plate (26) is provided between the first feed device (4) and the clamping device (8), in that the guide plate (26) is provided with a plurality of openings (36) and in that the space above the guide plate (26) is enclosed by a damping hood (41), which is spaced from the loop (7a).
2. Apparatus according to claim 1, characterized in that the guide plate (26) is bowed upwardly relative to a plane (E-E) tangential to the feed elements (5) of the first feed device (4) and the clamping elements (11, 12) of the clamping device (8), transversely relative to the feed direction (A).
3. Apparatus according to claim 1 or 2, characterized in that deflector plates (37, 38) affecting the loop formation are provided in the front and rear regions of the guide plate (26) relative to the paper feed direction (A), above the guide plate and oppositely inclined toward one another.
4. Apparatus according to claim 3, characterized in that the inclination of each deflector plate (37, 38) relative to the guide plate (26) is adjustable.

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