EP1657197A2 - Method for controlling a web tension - Google Patents

Abstract

The tension control method uses a tension regulator for compensating a defect occurring in the web (01) during its manufacture which affects its tension, for maintaining the tension within a permissible range, by reducing the required tension value. An independent claim for a device for regulating the tension of a web fed through a web processing machine is also included.

Description

The invention relates to a method for controlling a web tension according to the preamble of claim 1.

A method for controlling the web tension is disclosed by EP 08 37 825 B1, in which, in addition to the measured actual values for the web tension, further parameters characteristic of the machine condition and process-related properties are used for the control. In addition to the currently measured voltage values, specifiable path-specific parameters also flow into the control algorithm.

DE 198 34 725 A1 shows u. a. a method for controlling a web tension, wherein web tension actual values before and / or after the printing units of a control device is supplied, which regulates the web tension at the infeed so that despite disturbances such. B. a varying modulus of elasticity of the web, the web tension is kept in an optimal range for the color and cut register.

In DE 197 54 878 A1 it is about to perform a winding hardness on a role as constant as possible or predefinable. In order to obtain a uniform roll-up curve, measured values on the roll-down curve are used to influence the forces according to the desired nominal paper roll characteristic (winding hardness). The measured values are then used together with empirical values for regulation.

From DE 19 66 795 A1 a method and a device of a pre-printed web is known, wherein in connection with a roll change a web tension is at least temporarily reduced, for example to ensure a correct line alignment for the re-printing.

In US Pat. No. 3,510,036 a web tension is temporarily lowered in connection with a roll change. In order to avoid a web break during the passage of the splice, the web tension is generally lowered to the lowest permitted value and fixed the time for a particular printing press.

The invention has for its object to provide a method for controlling a web tension.

The object is achieved by the features of claim 1.

The achievable with the present invention consist in particular in that by means of a pre-regulation or feedforward at a predictable disturbance, in particular a roll change, expected effect on the printing process reduced, and thus the accumulated amount of waste can be minimized. The regulation takes place shortly before or with the occurrence of the fault on an affected unit and not after a negative effect. By means of this method, a long settling time and the risk of a web break can be reduced. The reduction or elimination of an effect on an expected disturbance thus accesses the disturbance itself, or proceeds without being dependent on retrospectively determined measured values at the same time as the structure of the disturbance. In a further development, measured values for the web tension can additionally be used. This can be advantageous for optimization and / or for a self-optimizing or learning system.

In particular, the disorder when changing substrates or their roles is counteract by means of the scheme and the accumulated amounts of waste can be minimized. In an advantageous embodiment, this is achieved in that when gluing, the section of the "old" train or entry of the beginning of a new printing material in the Pressing a pre-regulation or precontrol of drives or adjusting elements with regard to the expected changes in the web tension occurs.

The pre-control or pre-regulation significantly reduces the response times of the feedback control during production (cause-effect countermeasure) and / or the time of a transient or asymptotic approach to the target value. A complex color register control to compensate for a negative impact of the roll change can be omitted. The voltage is preferably lowered at the intake train in one embodiment by a predetermined value, and in another embodiment to a certain, predetermined value.

If a web tension control for the current operation of the printing press already exists, it is advantageous to connect an offset to the target value for the web tension control at the feed train. This offset can be superimposed as a one-time amount, as discrete steps or as a continuous function within a time interval to the setpoint at the infeed station. The time interval can be z. As a function of the duration of the splice from the reel splicer to funnel inlet, d. H. depending on the production speed (speed) and possibly the travel path. In another embodiment, the offset or the ramp without ramp at the relevant time in the form of a step function is abandoned.

If there is no automatically operating control during production, the actuators or the individual drives can still, for example by means of a corresponding control command, already with entry or in advance of the occurrence of the fault, z. B. the new web start in the printing press, a correction, so as to minimize the expected error or compensate.

Embodiments of the invention are illustrated in the drawings and will be described in more detail below.

Fig. 1

eine schematische Darstellung einer Rotationsdruckmaschine mit Regelung der Bahnspannung;

Fig. 2

eine schematische Darstellung des zeitlichen Verlaufs einer Spannung ohne Anwendung das Verfahren;

Fig. 3

eine schematische Darstellung eines ersten Ausführungsbeispiels für den zeitlichen Verlauf der Änderung eines Sollwertes für die Regelung der Spannung;

Fig. 4

eine schematische Darstellung eines zweiten Ausführungsbeispiels für den zeitlichen Verlauf der Änderung eines Sollwertes für die Regelung der Spannung;

Fig. 5

eine schematische Darstellung eines dritten Ausführungsbeispiels für den zeitlichen Verlauf der Änderung eines Sollwertes für die Regelung der Spannung.

Show it:

Fig. 1

a schematic representation of a rotary printing machine with regulation of the web tension;

Fig. 2

a schematic representation of the time course of a voltage without application of the method;

Fig. 3

a schematic representation of a first embodiment of the time course of the change of a setpoint for the control of the voltage;

Fig. 4

a schematic representation of a second embodiment of the time course of the change of a setpoint for the control of the voltage;

Fig. 5

a schematic representation of a third embodiment of the time course of the change of a setpoint for the control of the voltage.

A processing machine, z. B. a web-fed rotary printing press, has along a production direction, d. H. along a path of a web 01, z. B. a printing substrate 01, in particular a paper web 01, in the transport direction T more processing stages or units.

This can be illustrated schematically for a web-fed rotary printing press as shown in FIG. B. a roll changer 02, an infeed 03, one or more printing units 04; 06, a tension roller 07, possibly a longitudinal cutting device 08, Wende 09 and register devices 11, such. B. a longitudinal register roller 11, a further draw roller 12, z. B. as so-called. Funnel inlet roller 12, and formers 13 and folding unit 14 with not shown cross-cutting devices. In addition, other processing stages, not shown, such. B. coating unit, dryer, etc., be arranged.

Each printing unit 04; 06 has one or more printing units 16; 17; 18; 19, z. B. double printing units 16; 17; 18; 19 for the two-sided printing, on, wherein the printing units 16; 17; 18; 19 can be arranged side by side or one above the other. Are several printing units 04; 06 present, they may be next to each other or one above the other, with horizontal or vertical course of the web 01.

The web 01 is unwound from the roll changer 02 and passes through the printing units 16; 17; 18; 19, which the web 01 successively z. B. print four times on the same page.

For repeat printing, the registration, for double-sided printing the registration and when merging several webs 01; 01 'or partial webs 01; 01 'and the cutting across the cut register, can be checked at one or more points along the path of the web 01, the Passer- or Registerhaltigkeit. This is done for fully automatic printing machines, for example by means of the measurement of the position of the printing units 16; 17; 18; 19 applied marks or printed images by means of a sensor, not shown. The signals of the sensor are supplied in this case a control unit, not shown, for the correction of registered deviations in the register and register, whereupon z. B. adjusting means such as longitudinal register rollers, angular positions, etc. are provided.

Changes in web tension are usually by measuring rollers at one or more points on the way of the web 01, such. Example, the measuring roller 21 shown by way of example behind the last printing unit 19, or determined in another suitable manner, processed in a control unit 22, and in deviation from a desired value or a permissible range back to this or these returned. On the measuring roller 21, for example, the voltage S1 is determined behind the last printing unit 19, processed in the control unit 22 and given a signal to the drive of the tension roller 07 and / or the feed unit 03 to maintain the desired voltage S1. In particular, a voltage S0 before the first printing unit 16 determines the level for all the stresses on the path of the web 01 to the hopper inlet and is regulated for example via the feed train 03.

A control principle which operates "in retrospect" in this manner leads, in the case of a measured, already occurred deviation of an actual value from a nominal value, back to the desired nominal value by triggering drives or actuators. Such a control principle is z. B. during the "normal" Fortdruckes, without strong fluctuations in the conditions used; It therefore reacts to changes that have already occurred and registered.

The cause of disturbances and resulting changes can be manifold: z. As changes in the machine state such as accelerations, changes in sizes from the printing process such as fountain solution or ink supply, changes in contact pressures, changes in the properties of the web 01 as the stress-strain behavior, the thickness, the moisture absorption, etc.

An essential, but also foreseeable disturbance is a roll change and the associated run of a connection 26 between an old and a new web 01, in particular a splice 26 by the printing press. The splice 26 has a larger compared to the thickness of the single web 01 Starch, optionally plus an adhesive tape or adhesive, and of the web 01 different elastic properties. In addition, old and new web 01 can also have different properties (moisture, winding hardness and / or stress-strain characteristics).

These disturbances, especially the latter, caused a strong change in the tension of the web 01 and associated register errors when entering the printing machine. The attributable to the roll change register error between the printing units 16; 17; 18; 19 are by means o. G. Register control can not be compensated or can only be compensated by means of complex technology.

The present method of regulation now provides for the imminent change in the voltage S0; S1 counteract in such a way that a setpoint specified by the regulation S0-soll; S1-should be changed, in particular lowered. In a first example, the setpoint is S0-soll; S1-soll should by a certain amount ΔS-soll compared to the "normal" setpoint S0-soll; S1-soll, and in a second example, at least temporarily, to a predefinable new setpoint S0-fix; Lowered S1-fix. Both are done in a preferred embodiment by lowering the target value S0-soll the voltage S0 before the first printing unit 16 by means of the feed unit 03rd

Fig. 2 shows schematically a time course z. As the voltage S1 without the application of the method described. As soon as the splice 26 passes through the retraction unit 03, a steep rise in the voltage S1 sets in, which continues until the splice 26 enters the funnel inlet. The same applies to the course of the voltage S0, but temporally somewhat "forward", d. H. in Fig. 2 to the left, offset. Thereafter, the voltage S1 is on a level increased by an amount ΔS1 level and degrades only slowly. The increased, and in particular with a large amplitude of the setpoint S0-soll; S1-should be different level in the voltages S0; S1 etc. caused by changing the elongation register errors between the printing units 16 to 19.

These register errors are now avoided or reduced in a first exemplary embodiment (FIG. 3) in that the desired value S0-soll for the voltage S0 is increased by the amount ΔS-should be lowered. This reserve amount ΔS-soll is advantageously variable and corresponds to z. B. an average empirical value for the expected, without corresponding reduction occurring increasing the voltage S0 by the amount ΔS0. The amount .DELTA.S-soll may in particular also be selected in such a way that the voltage S0 resulting from the change in the setpoint value S0-soll after the reduction is initially below the original setpoint value S0-soll; S1-soll, and after passing through the setpoint S0-soll; S1-soll should be above the setpoint S0-soll; S1-soll should oscillate, with the respective absolute deviation in the minimum or the maximum of the original setpoint S0-soll; S1-should be significantly higher than the resulting deviation without the sag. The voltage S0; S1 then oscillates with significantly reduced amplitude around the original setpoint S0-soll; S1-soll. This amount ΔS-soll can z. B. in a memory unit 23 or arithmetic unit 23 (FIG. 1) deposited or determined. In the event that the changes in the voltages S0 and S1 are the same, it can correspond to the amount ΔS1 shown merely as an example for the voltage S1 in FIG. 2 or, as described above, to a proportion of this amount ΔS1. But it can also be via one of Fig. 2 corresponding time course of the voltage S0 or in any other way, for. B. by experiments.

In Fig. 3 is a schematic, and parallel to the voltage S0 or S1 of Fig. 2, the time course of the setpoint S0-soll applied. During the passage of the splice 26 through the retraction 03 or shortly before (in particular shortly before pressing a blade or at the latest at this time), the target value S0-soll is lowered. This can be done in a single step, continuously (eg as a ramp) or in several stages as shown in FIG. In the present embodiment (FIG. 3), the setpoint value S0-soll is not lowered in one step, but in a time interval Δt, which can be determined from the empirical values on the one hand and, in particular, by the transit time of the web 01 from the infeed 03 to the hopper infeed roller 12. The setpoint value S0-soll, which is ultimately reduced by the amount .DELTA.S-soll, may in one embodiment be increased by a time interval .DELTA.t '(FIG. 3) over the time of the expected without lowering Maximum of the voltage S1 (FIG. 2), before the setpoint value S0-soll is then returned to the setpoint value S0-soll desired for the machine state either in one step, continuously or stepwise. The "normal" voltage regulation then takes over again the regulation of the voltages S0; S1 etc, if available.

In a second exemplary embodiment (FIG. 4), the setpoint value S0-soll is not lowered by a fixed amount ΔS-soll, but temporarily to a fixed, but predeterminable and / or variable new value S0-fix. Thus, for example, can be ensured that the voltage S0 before the printing unit 04 does not fall so far that the voltage S1 behind the printing unit 04 in a critical for the web running area, z. B. below 8 daN / m, drops.

In Fig. 4, the time course of the setpoint S0-soll is shown, which initially remains at a constant level. This setpoint S0-soll is now intentionally lowered to a fixed value S0-fix in the context of a foreseeable disturbance, in particular a roll change. As already stated, the lowering can in principle be carried out at any, but fixed, point in time relative to the time of the roll change, and triggered by a wide variety of signals present or also measured by the control / regulation of the printing press.

It is advantageous, however, if the lowering takes place at the latest on entry, better still shortly before the occurrence of the disorder. In the case of the flying reel change considered, the disturbance occurs with the sticking of the new web 01 to the old web 01 and the almost simultaneous cutting off of the old web 01. This point in time t _K (gluing and / or cutting) forms in an advantageous embodiment the reference point for lowering the setpoint value S0-soll for the voltage S0 in front of the pressure unit 04 by means of the retraction unit 03.

Although the lowering is fixed in the example of FIG. 4 on the bonding process (activation of the adhesive roller and / or the bladed knife), but not at the time t _K of triggering the adhesive roller and / or the blunting knife, but in anticipation of sticking / cutting earlier respectively. As shown in Fig. 4 by the time interval .DELTA.t _K , the lowering of the setpoint S0-soll is carried out in a fixed, but adjustable time interval before the time t _K of sticking / cutting. The time interval is, for example, between 50 and 400 ms, in particular 50 and 250 ms. By means of the selection of the time interval .DELTA.t _K , an adaptation and optimization of the above-mentioned "transient response" to the printing press and the paper path can take place.

As the time for the lowering of the nominal value S0-soll prior to the actual point in time t _K of the bonding / cutting is, it is advantageous to fasten the timing of the lowering of information about the machine state or of measured values, by means of which also the time t _K for gluing / cutting is determined. This can be, for example, a determined diameter of the old, to be changed role. Also, the time for lowering may be correlated relative to a process related to gluing / clipping in direct temporal relationship. Such a process, for example, represents the positioning of an adhesive frame, ie, a time t _{S of} the signal for pivoting. Such a time t _S is z. B. 100 to 500 ms before the time t _K for gluing / cutting, so that the lowering is about 50 to 450 ms after the time t _S for pivoting. The lowering can, for example, at a certain roll diameter, z. 130 mm, and gluing / cutting at 125 mm. The distance between the two variables used can also be correlated with the instantaneous production speed or rotational speed (eg linear).

The setpoint input, ie the setpoint S0-setpoint, is now z. B. lowered without time ramp in one step to S0-fix, and remains there for a constant, but predeterminable time interval .DELTA.t1. Subsequently, the target value S0-Soll along a Ramp (possibly also along a step function) within a time interval .DELTA.t2 again raised to the original setpoint S0 target. The time intervals .DELTA.t1 and .DELTA.t2 are z. B. in the same order of magnitude, for example, 0.5 * .DELTA.t1 ≦ .DELTA.t2 ≦ 2.0 * .DELTA.t1. In principle, it is also possible the reduction stepwise or along a z. B. make steep ramp.

Is for another production - z. B. other paper guide, different order of the web 01 at the hopper inlet - another basic level for the voltages S0; S1 of the web 01 desired, so is the target value S0-soll ', as shown in Fig. 4 by way of example at a lower target value S0-soll', first on this target value S0-soll ', before he also on the fixed value S0-fix is lowered after the time interval .DELTA.t1 then within the time interval .DELTA.t2 to its original setpoint S0-soll 'to be returned.

In Fig. 1, an example of a possible control loop for the control of the voltage S0 is schematically integrated. The control unit 22 ensures in a usual control circuit that the voltages S0; S1 on each of the desired setpoint S0-soll; S1-should be held. For this, actual values S0-ist; S1-is supplied as input values, these with the setpoint values S0-soll; S1-shall be compared and provided by appropriate output values corresponding drives. The setpoints S0-soll; For example, S1-soll may be supplied from a machine control 24, or else quantities g supplied from the control unit 22 and characterizing the machine condition may be formed in the control unit 22 itself.

When changing roles, z. B. at the time of joining, the knocking off of the "old" web 01 or the passage of the splice 26 by the retraction 03 or in a time interval .DELTA.t _K relative to one of these times, in the first embodiment, from the memory or computing unit 23rd provided amount ΔS-soll as a negative "offset" z. B. as a step function on the setpoint S0-soll is added, and after reaching the final value z. B. for the time interval At 'maintained. In the second embodiment, the target value S0-soll is lowered to the value S0-fix, to hold it there for the time interval At and then return it along a ramp to its original value. If the fault has ended, ie, the splice 26 on the former 13 or the additional time interval Δt 'or the time interval Δt2 has elapsed, then the regulation returns to the "normal" voltage regulation with the predetermined setpoint values S0-soll; S1-soll etc. leave.

The memory or computing unit 23 are in a development of the invention in addition to the information about the material, eg. As the paper type, and z. B. web width in addition essential, the properties or the behavior of the web 01 influencing variables g from the printing process, the machine condition and / or the web guide, such. B. dampening solution and / or ink supply, current web tension, contact pressures, speed, temperatures, accelerations and / or path of the web 01, respectively. From this, in the first exemplary embodiment, the suitable temporary correction of the setpoint value S0-soll can be selected or calculated by the amount ΔS0 for the voltage S0 or the optimized time sequences (time points and time intervals Δt; Δt1; Δt2, Δt ') in the two exemplary embodiments determine or retrieve for the corresponding production.

It is also advantageous if data for previously determined amounts ΔS0 and / or ΔS-soll and the present circumstances are stored in the memory or computing unit 23. Such a memory or computing unit 23, together with the control unit 22 in a further development, can then be designed as a self-learning system, and thus optimize the control process taking place on the reel change in anticipation or at the same time. Ideally, after complete withdrawal of the amount ΔS-soll, no readjustment of the voltages S0; S1, so that this can be used as a measure of the quality achieved in the correction.

For triggering the lowering of the setpoint S0-soll, any other suitable method can be used. For example, detecting the steep edge of one of the voltages S0; S1, an optically detected passage of the splice 26 at some point, or the definition of a time relative to the roll change in the context of a program of the machine control determine the time. However, it is important that in order to counteract the disturbance, the setpoint for the voltage is intentionally changed at least temporarily, and not only after the extent of the negative disturbance has been determined.

In a third embodiment, the target value S0-soll, in contrast to the second embodiment of the fixed value S0-fix not along a predetermined ramp, but on the basis of a measurement of the voltage S1; S0, in particular the voltage S1 behind the last printing unit 19, z. B. measured by means of the measuring roller 21, to the original setpoint S0-soll (or a new fixed setpoint S0-soll ') returned. A new fixed setpoint S0-soll 'may be required, for example, if z. B. with the roll change and the paper type, i. the basic properties, should be changed. This information can then, for example, taken back from the machine control and in the formation of the setpoint S0-soll; S1-soll; S0-soll 'should be considered for undisturbed operation.

The recirculation may for example be based on continuous or discontinuous measurement value decrease, however, in particular, possibly selectable time intervals .DELTA.t _m based on the measured value and for the next time interval m valid setpoint S0-soll _m determined and the control is supplied. A resulting step-like feedback of the setpoint value S0-soll is shown by way of example in FIG. However, the return to the original setpoint S0-soll (or a new setpoint fixed value S0-soll ') can also be determined and specified in another way on the basis of the measured values S1-ist. So z. B. from two or more measured values sections of a slope of partial ramps are determined, in which case the one shown in Fig. 4 Ramp can then depending on the measured values sections have different slopes.

The determination and regulation of the setpoint values S0-soll _m or the sections-wise defined gradients can be determined from the measurements in an advantageous embodiment, for. B. based on a fuzzy control, be executed in a simpler version by means of a PID controller.

In principle, it is possible to combine the procedures of the three aforementioned examples. So z. B. a lowering of Example one and a return to Example three take place. Also in all three examples (possibly changeable) ramps can be specified for the lowering. The feedback from the third example can also be applied to the second example. Likewise, the lowering by a certain amount .DELTA.S-soll can be transferred to the examples two and three, while the lowering to a certain fixed value S0-fix on the example is a transferable.

01

Bahn, Bedruckstoffbahn, Papierbahn, Teilbahn

02

Rollenwechsler

03

Einzugswerk

04

Druckeinheit

05

-

06

Druckeinheiten

07

Zugwalze

08

Längsschneideeinrichtung

09

Wendeeinrichtung

10

-

11

Registereinrichtungen, Längsregisterwalze

12

Zugwalze, Trichtereinlaufwalze

13

Falztrichter

14

Falzwerk

15

-

16

Druckwerk, Doppeldruckwerk

17

Druckwerk, Doppeldruckwerk

18

Druckwerk, Doppeldruckwerk

19

Druckwerk, Doppeldruckwerk

20

-

21

Messwalze

22

Regeleinheit, Regeleinrichtung

23

Speichereinheit, Recheneinheit

24

Maschinensteuerung

25

-

26

Verbindung, Klebestelle

01'

Bahn, Teilbahn

T

Transportrichtung

g

Größe

S0

Spannung

S1

Spannung

S0-ist

Istwert der Spannung

S1-ist

Istwert der Spannung

S0-soll

Sollwert der Spannung

S0-soll_m

Sollwert der Spannung

S1-soll

Sollwert der Spannung

S0-fix

fixer Sollwert

S1-fix

fixer Sollwert

S0-soll'

Sollwert der Spannung

ΔS0

Betrag, Erhöhung

ΔS1

Betrag, Erhöhung

ΔS-soll

Betrag, Absenkung

Δt

Zeitintervall

Δt'

Zeitintervall

Δt1

Zeitintervall

Δt2

Zeitintervall

Δt_K

Zeitintervall

Δt_m

Zeitintervall

t_K

Zeitpunkt, Kleben/Abschneiden

t_S

Zeitpunkt, Schwenken

LIST OF REFERENCE NUMBERS

01

Web, substrate web, paper web, partial web

02

reelstands

03

infeed

04

printing unit

05

-

06

printing units

07

pulling roller

08

Slitter

09

turning device

10

-

11

Register devices, longitudinal register roller

12

Pull roller, hopper inlet roller

13

formers

14

folding

15

-

16

Printing unit, double printing unit

17

Printing unit, double printing unit

18

Printing unit, double printing unit

19

Printing unit, double printing unit

20

-

21

measuring roll

22

Control unit, control device

23

Storage unit, arithmetic unit

24

machine control

25

-

26

Connection, splice

01 '

Train, subway

T

transport direction

G

size

S0

tension

S1

tension

S0 is

Actual value of the voltage

S1 is

Actual value of the voltage

S0-soll

Setpoint of the voltage

S0-shall _m

Setpoint of the voltage

S1-soll

Setpoint of the voltage

S0-fix

fixed setpoint

S1-fix

fixed setpoint

S0-soll '

Setpoint of the voltage

ΔS0

Amount, increase

ΔS1

Amount, increase

.DELTA.S-to

Amount, reduction

.delta.t

time interval

.delta.t '

time interval

.DELTA.t1

time interval

.DELTA.t2

time interval

Δt _K

time interval

Δt _m

time interval

t _K

Time, gluing / cutting off

t _s

Timing, panning

Claims (24)

Method for regulating a voltage (S0; S1) of a web (01) passing through a processing machine, whereby disturbances occurring during production, which influence the voltage (S0; S1), are compensated by means of a control device (22), and the voltage (S0; S1) is held at a desired value (S0-soll; S1-soll) or within a permitted range, and wherein at least temporarily the desired value (S0-soll; S1-soll) for the voltage (S0; S1) or the permitted range is opposite a currently existing setpoint value (S0-soll; S1-soll) is lowered, characterized in that the return of the setpoint value (S0-soll) for the voltage (S0) in front of the first printing unit (16) using measured values for the voltage (S0). S1) behind the last printing unit (19). Method according to Claim 1, characterized in that the desired value (S0-soll; S1-soll) for the voltage (S0; S1) or the permitted range is lowered to a fixed value (S0-fix). A method according to claim 1, characterized in that the desired value (S0-soll; S1-soll) for the voltage (S0; S1) or the permitted range by a predefinable amount (.DELTA.S-soll) compared to the currently existing desired value (S0-). should, S1-soll) is lowered. A method according to claim 1, characterized in that a memory unit (23) is provided, in which at least one value for the amount (ΔS-soll) of the change of the setpoint (S0-soll; S1-soll) or for the fixed value ( S0-fix) is deposited. A method according to claim 1, characterized in that a memory or arithmetic unit (23) is provided, in which at least one connection for the determination of an amount (ΔS-soll) of the change of the setpoint value (S0-soll; S1-soll) is stored. A method according to claim 4 or 5, characterized in that the value for the amount (.DELTA.S-soll) or the value (S0-fix) of the change is vorgeb- and / or changeable. A method according to claim 1, characterized in that the lowered setpoint (S0-soll; S1-soll) is maintained for a constant, but predeterminable time interval (.DELTA.t1). A method according to claim 1, characterized in that the changing or lowering of the setpoint (S0-soll; S1-soll) takes place in a step substantially without time extension. A method according to claim 4, characterized in that the changing or lowering of the desired value (S0-soll; S1-soll) takes place discontinuously at time intervals. A method according to claim 1, characterized in that the change of the setpoint (S0-soll; S1-soll) takes place in the run-up or during the fault. A method according to claim 1, characterized in that the change of the setpoint value (S0-soll; S1-soll) takes place to compensate for a disturbance caused by a roll change. A method according to claim 1, characterized in that the change of the setpoint (S0-soll; S1-soll) to compensate for as a connection (26) of a new with an old train (01) formed disturbance takes place. Method according to Claim 3, characterized in that the change takes place by the predefinable amount (ΔS-soll) in such a way that it counteracts the expected change in the voltage (S0; S1). Method according to Claim 1, characterized in that the desired value (S0-soll; S1-soll) for the voltage (S0; S1) is changed in front of a first printing unit (16) located in the direction of transport (T) of the web (01). Method according to Claim 14, characterized in that the change in the setpoint value (S0-soll; S1-soll) at the intake unit (03) is effected. A method according to claim 14, characterized in that the change of the setpoint (S0-soll; S1-soll) takes place at the latest with a connection of an old train (01) with a new track (01). A method according to claim 14, characterized in that the change in the desired value (S0-soll; S1-soll) at the latest when passing through the connection (26) by a last nip in front of a first printing unit located in the transport direction (T) of the web (01) (16) takes place. Method according to Claim 1, characterized in that after the setpoint has been changed or lowered (S0-soll; S1-soll), it is kept constant at the new level for a predefinable time interval (.DELTA.t1). A method according to claim 18, characterized in that the desired value (S0-soll; S1-soll) after the time interval (.DELTA.t1) is returned to its original constant value for steady-state operation. A method according to claim 18, characterized in that the desired value (S0-soll; S1-soll) after the time interval (Δt1) to a new constant, from the original setpoint (S0-soll; S1-soll) deviating value for steady-state operation is returned. A method according to claim 19 or 20, characterized in that the return of the desired value (S0-soll; S1-soll) takes place on the basis of a predetermined function as a function of time. Method according to Claim 19 or 20, characterized in that the feedback of the setpoint value (S0-soll; S1-soll) is carried out using measured values for the voltage (S0-is; S1-ist). A method according to claim 1, 21 or 22, characterized in that the return of the desired value (S0-soll; S1-soll) occurs discontinuously at time intervals (Δt _m ). A method according to claim 1, 21 or 22, characterized in that the return of the setpoint (S0-soll; S1-soll) takes place continuously on the basis of at least one temporally defined relationship in sections.

Images