Method and device for processing a paper or film web

Abstract

The invention relates to a method for processing a paper or film web (10). According to said method, the web (10) is first fed underneath a braking element (12), scanned by a reader (15) and subsequently conveyed at varying speeds by a conveyer drive (16). The braking element (12), e.g. a brush (30), exerts a varying braking force on the paper or film web (10), thus holding the web (10) taut and preventing undulations in said web between the braking element (12) and the conveyer drive (16). This improves the legibility of control marks for the reader (15), reduces the load on the conveyer drive (16) and prevents paper-feed malfunctions. The method can be advantageously used to feed a paper or film web (10) in a stop-and-go operation to a cutting device (22), which cuts the web (10) transversally to the direction of transport using a guillotine (24).

Description

TECHNICAL FIELD

The invention relates to a method for processing a paper or film web, the web first being fed underneath a braking element, then scanned by a reader and finally conveyed at varying speeds by a conveyor drive. The invention also relates to a device for carrying out the method and to the use of the device for feeding the paper or film web to a cutting device.

PRIOR ART

It is often necessary for large quantities of paper, for example invoices, reminders, account statements, round robins or other printed material to be processed quickly and completely in an automated manner. Firstly, printing of an endless paper web is usually carried out by a high-speed high-performance printer. The web then has to be cut at the same speed and, depending on the printed matter, into various formats, such that the individual sheets can be processed further, in particular packed for dispatch by mail. The information as to where and how cutting is to be carried out is generally predefined by control features applied to the web, for example printed on. Accordingly, fast, flexible and fault-tolerant cutting devices are needed.

Particularly cost-effective and simple in construction are cutting devices having transverse knives which separate sections from the web in the manner of a guillotine. Such transverse knives necessitate feeding the paper web to be counted in stop and go operation, that is to say the paper web must be stopped for cutting and then accelerated again.

DE 37 00 112 A1 (Bernd Kunzmann) shows such a cutting device for a paper web, a supply loop being formed first, from which it is possible for a paper web section to be pulled forward to the cutter quickly by a haul-off roll. Between the supply loop and the haul-off roll, a brush strip is firstly arranged fixedly as a braking element. This is followed by a printed mark scanning device, which forms part of the control apparatus of the cutting device. The paper web is stopped briefly and, after the haul-off roll, is cut by a transverse knife bar interacting with a stationary knife.

This arrangement places limits on the maximum achievable conveying speed and therefore the possible number of processed sheets. The higher the processing speed chosen, the higher are the accelerations and retardations to be achieved. Particularly when stopping the paper web, high forces act on the web and there is the risk that the paper will tear, in particular if there are any perforations. A further problem is that, at a high processing speed, the paper web is no longer flat between braking element and haul-off roll, which makes the scanning, in particular optical scanning, of the printed marks more difficult or even impossible. Furthermore, the arrangement leads to high loading on the drive of the haul-off roll. This therefore has to be dimensioned in a correspondingly expensive way.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method, belonging to the technical field mentioned at the beginning for processing a paper or film web, which permits a high processing speed and relieves the load on the conveyor drive.

The achievement of the object is defined by the features of claim 1. According to the invention, the braking element acts with a varying braking force on the paper or film web, so that the web is tautened and the formation of undulations of the web between braking element and conveyor drive is avoided.

The solution according to the invention permits adaptation of the effect of the braking element to the dynamics of the paper or film transport, that is to say to the acceleration or retardation of the paper web respectively carried out by the conveyor element. As compared with a braking element for a constant braking force, the braking action exerted on the web in this way can be intensified or reduced. By means of the respectively optimal adaptation of the braking force, the formation of undulations of the paper or the film under high retardations and also tearing of the paper or the film under high accelerations can be avoided. To the same extent, optimal adaptation of the feed to different conveying rates, which are necessitated by the further processing or by fluctuating utilization, for example, is made possible.

The braking element is advantageously pressed against the paper or film web in a dragging manner with a varying contact pressure. Depending on the contact part of the braking element interacting with the web, in particular its shape, surface and coefficient of friction, an average braking force of the braking element can be selected. A low contact pressure then corresponds to a low braking force, a high contact pressure to a high braking force. Braking elements of this type can be produced cost-effectively and simply, and they can be adapted simply and flexibly to the various requirements, for example the material conveyed, its cross section, its width, the conveying speed and so on.

As alternatives, for example rolls, rollers or pairs of rolls or pairs of rollers can be selected as the braking element, their surfaces generally rolling on the paper film web, that is to say having no slippage with the web. By changing the rolling resistance, for example by means of braking the rollers with a pressing element with a varying contact pressure or by means of an eddy current brake which acts on the roll or roller axle, the braking force of the roll or rollers can likewise be varied. Rollers or rolls and their suspension, as well as appropriate elements for changing the rolling resistance, are certainly structurally more complicated and therefore normally more expensive in fabrication and mounting and are mechanically less durable than a dragging braking element, but their characteristics can be defined better and adapted to the application over a wide range.

If the paper or film web is accelerated and braked periodically by the conveyor drive, then a higher force is advantageously chosen during braking than during acceleration. This permits the braking force to be reduced during the acceleration phase, as compared with a braking force acting continuously with the same force. As a result, the force necessary for the acceleration is reduced and the web can be conveyed without hindrance during the acceleration phases. The acceleration can be carried out more quickly, so that the processing speed is increased. At the same time, the load on the conveyor drive is relieved. During the braking phase, on the other hand, the braking force can be increased as compared with a fixed braking element. This shortens the braking phase during which the conveying speed has already been reduced but the web cannot yet be cut. As a result, the processing speed is increased further.

Between acceleration and braking phase, the transport of the paper film web is carried out at maximum conveying speed. During this time period, the braking force of the braking element can be adapted to the configuration of the device, the thickness and the material of the paper or film web processed and the size of the sheets to be cut. As a rule, an average braking force will be selected, which lies between the braking force in the acceleration phase and that in the braking phase. As a result of the continuous adaptation of the braking force, the paper film web is tautened and undulation of the web between braking element and conveyor drive is prevented during the entire conveying operation. As a result, markings which are printed on the paper or film web or applied in another way and which, for example, are used to control a cutting device, can be read reliably during the entire conveying operation.

The braking element advantageously acts on the web with the higher braking force substantially after the start of braking the paper or film web and at least as far as the stoppage of the web. During this time period, there is otherwise the risk that the web at the level of the braking element would continue to be moved along with a speed higher than the conveyor drive, because of its inertia; undulations would be the consequence. Otherwise, the braking force is increased continuously or gradually, so that shock-like loading of the paper or film web by a braking force which is established suddenly is avoided.

The braking element is advantageously a movable brush. The bristles create a certain amount of elasticity in the conveyance of the web. Their material and thickness can be matched to the paper or film material to be processed. The brush can additionally be produced cost-effectively, does not require exact adjustment and is mechanically very durable. Finally, the mechanical loading of the paper or film web is largely minimized on account of the large number of bristles which each transmits only a small force to a small part of the web.

The braking element can alternatively also be formed as the moveable hold-down. Its braking action depends, apart from the contact pressure, on its shape, its surface material and its elasticity. For instance, a movable flap of a thin, elastic plastic or polymer material is suitable which, in a manner similar to a brush, is pressed onto the paper web at a shallow angle with a varying contact pressure.

The contact pressure of the dragging braking an element is preferably set by means of a rotary magnet having two, in particular adjustable, stops. The two stops correspond to a lower and a higher contact pressure of the braking element.

The rotary magnet can be actuated simply. If a certain voltage is applied, it assumes the first of its two positions. Without any voltage, it moves into its other position, for example by means of a restoring spring or as a result of the weight of the brush. Adjustable stops additionally permit simple mechanical adaptation of the rotary magnet to various requirements with regard to contact pressure, therefore in relation to various thicknesses of the paper or film web to be processed. In the simplest case, the adjustable stops substantially each comprise a fixedly mounted setting screw and a stop arranged on the moving part of the magnet.

By means of variation of the voltage applied to the rotary magnets, the resistance of the braking element in one of its two positions can likewise be determined.

If the behavior of the braking element can be determined exactly, the contact pressure of the braking element is advantageously set by a motor. Appropriate linear or stepping motors permit rapid and precise control of the braking element. In the event of strictly periodic movements of the braking element, it can additionally interact with mechanical means, such as cam disks.

Alternatively, the contact pressure of the braking element can also be determined by a lifting magnet, for example.

A transport speed of the web and/or a tension of the web is/are preferably measured and the braking force is set on the basis of the measured transport speed and/or tension. The real-time determination of such parameters permits continuous adaptation of the setting of the braking force of the braking element. The latter can, for example, always be chosen such that the tension of the web falls below a set maximum value and that tearing of the web is therefore made impossible. Alternatively or additionally, the transport speed of the web can, for example, the measured at the braking element and at the conveyor element and the braking force can be set such that the difference in the speeds does not exceed a set maximum value. In this way, a method for processing a paper or film web can be provided which adapts automatically to the material processed, the conveying speed and further parameters.

Alternatively, the control of the braking force can be carried out via a predefined program or a corresponding mechanical control system, which are adapted to the processing process.

A device for processing a paper or film web comprises a braking element, a conveyor drive arranged after the braking element for accelerating and retarding the web and a reader for scanning the web between the braking element and the conveyor drive. The braking element acts on the paper or film web with a varying braking force, such that the web is tautened and the formation of undulations of the web between braking element and conveyor drive is avoided.

The device according to the invention is used in particular for feeding a paper or film web in stop and go operation to a cutting device, which cuts the web transversely with respect to the transport direction by means of a guillotine during a stoppage. The cut by means of a guillotine may be implemented constructionally simply and, as a result, cost-effectively. During the cutting of a paper web by such knives, however, the web must generally remain still. The corresponding stop and go operation places increased requirements on the feeding of the paper or film web. This must be offered to the knife without undulations and, during acceleration and braking, must not be subjected to excessively high loadings, so that tearing of the web is ruled out.

The reader detects control features and controls the cutting device. The control features can be formed optically or magnetically, for example, and can be printed on the paper web or applied in another way, for example in the form of a magnetic strip. It is advantageously possible to detect control features which are located at any desired position on the paper or film web or on the sheets to be cut. In this way, the cutting device can be used universally with a large number of different marking formats. In order that this can be achieved, the reading area between braking element and conveyor drive advantageously has such a large longitudinal extent that the longest documents to be cut have room along this reading section. The reader then has a recording range which corresponds at least to this area, or it can be moved out of this area to that location at which the markings are respectively arranged in the currently processed paper or film web.

A braking element for a device for processing a paper or film web has means for acting on the web which are composed in such a way that the action can be carried out with a varying braking force.

Further advantageous embodiments and feature combinations of the invention emerge from the following detailed description and all of the patent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings used to explain the exemplary embodiment:

FIG. 1 shows a graphical representation of the dynamics of the conveyance of a paper or film web in stop and go operation;

FIG. 2 shows a schematic representation of a device according to the invention for processing a paper or film web;

FIG. 3 shows a graphical representation of the cost of the braking force during a method cycle;

FIG. 4 shows a schematic representation of the sensors and the control of a device according to the invention;

FIG. 5 shows a schematic representation of a movable brush according to the invention.

In principle, identical parts are provided with identical designations in the figures.

WAYS OF IMPLEMENTING THE INVENTION

FIG. 1 shows a graphical representation of the dynamics of the conveyance of a paper or film web in stop and go operation. In shows the variation of the web speed 1 as a function of the time 2, somewhat more than one method cycle being covered. The cycle is divided up into a number of phases.

In a first phase, the acceleration ramp 3, the conveying speed is increased from a standstill until a certain conveying speed 4 is reached. In the next phase, the conveying phase 5, the web is transported onward at the conveying speed reached. This phase forms the main part of the cycle and is represented in shortened form in the figure. This is followed, as the third phase, by the braking ramp 6, during which the speed is reduced again down to a standstill. During these three phases 3, 5, 6, the transport of the web is carried out, its total duration therefore corresponding to a transport time 7. This is then followed by the stoppage time 8, during which the web can be cut. Therefore, one method cycle with a cycle time 9 has elapsed and the next, generally identically progressing cycle follows.

In order to optimize the processing speed, the acceleration ramp 3 and the braking ramp 6 should now be as short as possible. This means that the highest possible accelerations and retardations are to be achieved. Nevertheless, when stopping the web, the formation of undulations is to be prevented and the web is to be tautened, if possible, during the entire retardation operation. The stoppage time 8 which is needed for cutting the web is likewise to be as short as possible. The advantage of the method according to the invention now manifests itself in that both the acceleration ramp 3 and the braking ramp 6 can be very steep and therefore take up less time. This is because, given the dynamics shown, during the acceleration, the braking force of the braking element is chosen to be low, so that less force has to be expended in order to accelerate the web, and in that, at the same time the paper or film tension is reduced. During the braking, on the other hand, the braking force is advantageously increased, so that the web can be braked rapidly at the conveyor drive without undulations appearing in front of the latter, which would lead to impaired legibility of control features by the reader and, under certain circumstances, to disruptions to the paper run.

FIG. 2 shows a schematic representation of a device according to the invention for processing a paper or film web, only the most important sentiments being represented. The paper or film web 10 is conveyed from a device arranged upstream, for example a supply roll, a supply stack, a high-performance printer or a festoon accumulator, to the device according to the invention. The paper web can have a perforated guide edge, in which teeth of a conveyor tractor engage. The device according to the invention is, however, particularly also suitable for paper without a perforated guide edge.

The device has a flat table 11, on which the web 10 rests flat. Arranged at the inlet to the device there is now a movable braking element 12, which has at least one setting 13 with a high braking force and one setting 14 with a low braking force. The braking element is followed by a reader 15, which recognizes and detects control features arranged on or applied to the web. The reader 15 simultaneously registers the area of an entire document to be cut, so that control features can be arranged on its entire area. For fault-free and fast operation of the reader 15 it is important that the area is as flat as possible and free of undulations. It is also possible to select a reader with a smaller detection area which, for example, corresponds only to the area of a marking to be registered. In this case, the region is positioned above the reading area such that the marking can be read when the document to be cut is resting on the area. If, at a later time, other documents with another arrangement of markings are to be processed, the reader is displaced manually or automatically to the appropriate point above the reading area.

There then follows the conveyor drive 16, which comprises two rollers 17 and 18. The upper roller 17 is a rubber pressure roller, which is pressed against the lower roller 18 with a certain pressure. The pressure can be generated, for example by a spring. The lower roller 18 forms the drive axle and is coupled to a motor. Its running surface has a high roughness in order that, in during high accelerations or retardations, no slippage with respect to the paper or film web 10 occurs.

FIG. 3 shows a graphical representation of the variation of the braking force 19 during a method cycle of the device according to the invention. For reasons of clarity, the speed 1 of the web is again represented in relation to the corresponding times of the cycle. In the device according to the invention, these are substantially determined by the conveyor drive, whose drive roller exhibits no slippage with respect to the web. During the acceleration ramp 3, a very low value of the braking force 19 is selected, in order not to reduce the acceleration and in order to relieve the conveyor drive of load as far as possible. The low braking force selected is used merely to guide the web at the inlet to the device and corresponds to the low frictional force which necessarily occurs between a web and a guide.

In the next phase, the conveying phase 5, a slightly increased value of the braking force 19 is set, the transition from the low to the slightly increased braking force being made continuously and gradually. The slightly increased value does not lead to any substantial loading of the conveyor drive but ensures stable running of the paper and film web, in that the latter is tautened between braking element and conveyor drive. This permits operation of the reader during the conveyance as well, if required.

The braking force 19 of the braking element is already increased gradually before the start of the braking ramp 6. This increase is not made abruptly, so that the paper or film wed is not excessively loaded. The braking force 19 reaches its maximum shortly after the start of the braking ramp 6; this value is maintained as far as the end of the braking ramp and therefore as far as the stoppage of the paper or film web. The slightly increased braking force during the conveying phase 5 contributes to reaching the maximum braking force more quickly.

During the stoppage time 8, the braking force can be dissipated again, in principle the entire stoppage time being able to be utilized for this purpose, since the braking force is hardly relevant during stoppage of the web. It is important that, when the renewed acceleration of the web begins, the braking force has reached its low value again, so that excessive loading of the web and of the conveyor drive is avoided.

If a braking element is chosen which only permits substantially two different fixedly adjustable braking forces, for example a brush which is actuated by a rotary magnet, then the same braking force is advantageously chosen during the acceleration ramp 3 and in the conveying phase 5. This corresponds to an average force between the very low and slightly increased force, which is sufficient both to guide the paper of film web during both phases and also loads the drive as little as possible. The transitions between the fixedly adjustable braking forces can be influenced by the design of the braking element, for example by the mass moment of inertia of its components, by springs or damping means, and adapted to the application.

FIG. 4 is a schematic representation of the sensors and the control of a device according to the invention. The reader 15 transmits the data detected, such as the location, content and time of a detected control feature, to the controller 20. The control features can be encoded in accordance with any desired standard or format, for example OMR, one-dimensional or two-dimensional bar codes, OME, BCR or OCR.

On the basis of this data and, if appropriate, further information which, for example, can be fixedly predefined by an operator or set via programming means, the controller 20 controls the motor 21 which is connected to the lower roller 18 of the conveyor drive 16, and also the cutting device 22, which has a drive 23, a movable guillotine 24 and a stationary opposing blade 25. Furthermore, following processing means, for example an envelope-filling machine for packing the documents into envelopes or a sorting system, can be controlled by the data determined by the reader.

The upper roller 17 of the conveyor drive 16 is coupled to a speed sensor 26, which measures the conveying speed of the paper or film web 10 at the conveyor drive 16. The corresponding data is transmitted to a second controller 27. The second speed sensor 28 measures the conveying speed of the web shortly after the braking element 12 and transmits this data likewise to the second controller 27. On the basis of the measured values, in particular the absolute value of the speeds and their difference, the motor 29 which is connected to the braking element 12 and sets the braking force is controlled.

The controller 20 for the conveyor drive and the cutting device, and also the second controller 27 for tautening the paper or film web are independent of each other in this example. However, they can be coupled to each other to exchange data. The implementation of those control functions in a single controller is also possible.

FIG. 5 shows a representation of a movable brush according to the invention, illustrated from above. The paper or film web 10 is pulled through under the movable brush 30, the bristles 31 of the brush 30 being oriented in the conveying direction of the web 10 but angled slightly thereto. The bristles 31 are arranged directly on an axis of rotation 32. This is mounted on spherical bearings in rotary magnets 33, 34, which are each fixed to the device according to the invention by a fixing angle 35, 36.

The behavior of the brush is influenced by a number of parameters. The number and density of the bristles 31 and the material used and the bristle length 37 are important. Finally, the angle of the bristles on the axis of rotation, therefore the contact pressure with respect to the web 10 and the braking force acting, can be varied as desired by actuating the rotary magnets. This angle advantageously forms with the paper web an acute angle of about 15-35°. The ends of the bristles therefore meet the web flat, and as a result to not lead to damage to the paper or film surface and, if required, can act on the web with a greater bristle length.

The cutting device, to which the paper or film web is fed by means of the device according to the invention, can also operate with other knives, for example a reciprocating knife or a rotary knife, instead of a guillotine. A rotary knife will generally not be operated in stop and go operation but a controlled feed of paper or film web can also be advantageous then, in order for example to permit satisfactory reading of control features by the reader, particularly at the high possible web speeds in devices with rotary knives.

In summary, it should be recorded that the invention provides a method for processing a paper or film web which permits a high processing speed and relieves the load on the conveyor drive.

Claims

1-17. (canceled)

18. A method for processing a paper or film web (10), the web (10) first being fed underneath a braking element (12), then scanned by a reader (15) and finally conveyed at varying speeds by a conveyor drive (16), characterized in that the braking element (12) acts with a varying braking force on the paper or film web (10), so that the web is tautened and the formation of undulations of the web between braking element (12) and conveyor drive (16) is avoided.

19. The method as claimed in claim 18, characterized in that the braking element (12) is pressed against the paper or film web (10) in a dragging manner with a varying contact pressure.

20. The method as claimed in claim 18, characterized in that the paper or film web (10) is accelerated and braked periodically by the conveyor drive (16), a higher force being chosen during braking than during acceleration.

21. The method as claimed in claim 19, characterized in that the braking element (12) acts on the web (10) with the higher braking force substantially after the start of braking the paper or film web (10) and at least as far as the stoppage of the web (10).

22. The method as claimed in claim 19, characterized in that the braking element (12) has a movable brush (30).

23. The method as claimed in claim 18, characterized in that transport speed of the web (10) and/or a tension of the web (10) is/are preferably measured and the braking force is set on the basis of the measured transport speed and/or tension.

24. A device for processing a paper or film web (10), in particular as a feed to a cutting device (22), comprising a braking element (12), a conveyor drive (16) arranged after the braking element (12) for accelerating and retarding the web (10) and a reader (15) for scanning the web (10) between the braking element (12) and the conveyor drive (16), characterized in that the braking element (12) acts on the paper or film web (10) with a varying braking force, such that the web (10) is tautened and the formation of undulations of the web (10) between braking element (12) and conveyor drive (16) is avoided.

25. The device as claimed in claim 24, characterized by means (33, 34) which press the braking element (12) against the paper or film web (10) in a dragging manner with a varying contact pressure.

26. The device as claimed in claim 24, characterized by a controller (20, 27) which controls the conveyor drive (16) such that the paper or film web (10) is periodically accelerated and braked, and which controls the braking element (12) such that the braking force is chosen to be lower during acceleration than during braking.

27. The device as claimed in claim 26, characterized in that the controller (20, 27) controls the braking element (12) such that it acts on the paper or film web (10) with the higher braking force substantially after the start of braking the paper or film web (10) and at least as far as a stoppage of the web (10).

28. The device as claimed in claim 25, characterized in that the braking element (12) has a movable brush (30).

29. The device as claimed in claim 25, characterized in that the braking element (12) comprises a rotary magnet (33, 34) having two, in particular adjustable, stops.

30. The device as claimed in claim 25, characterized in that the braking element (12) comprises a motor (29).

31. The device as claimed in claim 26, characterized in that it comprises a measuring device (26, 28) which measures a transport speed of the web (10) and/or a tension of the web (10), and in that the controller (20, 27) comprises means for setting the braking force on the basis of the transport speed and/or tension measured by the measuring device (26, 28).

32. The device as claimed in claim 26, characterized by a cutting device (22), which cuts the paper or film web (10) transversely with respect to the transport direction by means of a guillotine (24) during a stoppage, the paper or film web (10) being fed to the cutting device (22) in stop and go operation.

33. The device as claimed in claim 32, the reader (15) detecting control features and controlling the cutting device (22).

34. A braking element for a device for processing a paper or film web (10), in particular as claimed in claim 24, characterized by means which press the braking element (12) against the paper or film web (10) in a dragging manner with a varying contact pressure.