EP1303403A1

EP1303403A1 - Method for regulating the tension of a web

Info

Publication number: EP1303403A1
Application number: EP01962576A
Authority: EP
Inventors: Michael Heinz Fischer
Original assignee: Koenig and Bauer AG
Current assignee: Koenig and Bauer AG
Priority date: 2000-07-22
Filing date: 2001-07-19
Publication date: 2003-04-23
Anticipated expiration: 2021-07-19
Also published as: US6810812B2; JP4108471B2; DE50114313D1; EP1303403B1; DE10035787A1; AU2001283779A1; DE10035787C2; WO2002007974A1; ATE407801T1; US20030188661A1; JP2004504190A

Abstract

The invention relates to a method for regulating the tension (52, 53, 55, 56, 57) of a web in a rotary press comprising at least one printing group (06, 07, 08, 09) that is provided with at least one first and one second cylinder between which a web is tensioned, whereby both cylinders are driven by at least one drive mechanism. The distance (a) between both cylinders is altered for the purpose of influencing the tensions of the web in front of, between and after the printing groups.

Description

description

Process for regulating a web tension

The invention relates to methods for regulating a web tension according to the preamble of claims 1 or 2.

EP 0951 993 A1 discloses a drive for a rotary printing press which contains a register, a longitudinal expansion of the printing material web being determined from the web tension and operating values of the drives, and being compensated for by adjusting the circumferential register on the cylinders or the register rollers.

In DE 42 11 379 A1 printing units are disclosed, the rubber cylinders of which are mounted in adjustable eccentric bushings, with the pivoting about the first eccentric axis starting the cylinders and pivoting about the second eccentric axis varying the printing width of an inking roller to the anilox roller.

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

The object is achieved by the features of claims 1 or 2.

The advantages that can be achieved with the invention consist in particular in that the printing units or units can be regulated in a simple manner via the prevailing tension or tension of the web, for example the printing material or paper web. This is done by changing the pressure provided between the cylinders acting together via the web, advantageously in the case of “rubber-against-rubber pressure” of the two interacting transfer cylinders of a printing unit. The conveying behavior of the web through a printing machine is subject to many influences such as the tension / elongation characteristics of the respective paper and thus the prevailing tension, the instantaneous moisture, the sensitivity to moisture, the penetration behavior of moisture into the web, and the position of the roll during its manufacture in the reel, which is reflected, for example, in different winding hardness and location-dependent fluctuations in the modulus of elasticity. It also depends on the lifts and the contact pressure.

The conveying behavior of the web through one or more printing units of the printing press can be influenced and regulated in an advantageous manner by means of the method, without a change of rubber blankets of different thicknesses or a change in the procedure, for example a change in the damping, being necessary. A change in the tension of the web can be counteracted during production by changing the conveying behavior. The use of different rubber blankets or different types of paper is also possible, since the conveying behavior and the print quality can be changed by changing the distance, not with the rubber blanket thickness.

Conversely, it is possible to use rubber blankets with different conveying behavior, different quality and / or different thickness, the desired web tension or gradation in web tension between the printing units being automatically stable almost constantly.

For example, rubber blankets from certain manufacturers have a "negative promotion", i.e. the web is "braked", and others "positive promotion", i.e. the web is "pushed" in addition to processing in the nip point.

The conveying behavior also depends on the contact pressure of the rubber blankets and the paper web. In an advantageous embodiment, the transfer cylinders are driven in pairs with their own drive. The forme cylinders, together with the inking and dampening units, which work together with the transfer cylinders, are specially driven and only synchronized with the transfer cylinders by electrical engineering. The resulting advantages include the avoidance of, for example, gear wheel play when the transfer and forme cylinders are mechanically coupled, and an almost torsionally rigid and angularly synchronous drive of the forme cylinders in relation to the transfer cylinders. In addition, fluctuations in torque, for example caused by distribution rollers or siphon inking units, are damped by the in-house drives for the forme cylinders, including the inking and dampening units, and are not transmitted to the transfer cylinders. This leads to largely undisturbed printing.

An embodiment of the invention is shown in the drawing and will be described in more detail below.

Show it:

Figure 1 is a schematic representation for guiding a web from the infeed unit via four printing units and a second pull roller to a funnel infeed roller.

Fig. 2 is a schematic representation of the tension of the web in continuous printing;

Fig. 3 is a schematic representation of a rubber-to-rubber printing unit without showing the inking and possibly dampening unit;

Fig. 4 is a schematic representation of a rubber / impression cylinder printing unit without depicting the inking and possibly dampening unit; 5 shows an exemplary dependency of the setpoints for the power consumption of the drives for the paired transmission cylinders;

Fig. 6 is a schematic representation of the control loop for a printing group i.

Fig. 1 shows schematically the course of a path B, z. B. a printing material web B or a paper web B, on its way through a printing press, in particular a web-fed rotary printing press. The web B runs in the transport direction T from the roll changer 01 via a feed unit 02 with a drawing roller 03 through, for example, printing units 06 to 09 to a second drawing roller 11. The second pull roller 11 is followed, for example, by turning bars, cutting knives, further pull or guide rollers (not shown) and ultimately a hopper feed roller 12. The main pull rollers 03; 11 are preferably each with its own drive 13; 14 and a drive control 16; 17 equipped. Before the infeed unit 02, between the infeed unit 02 and the first printing unit 06 and between the last printing unit 09 and the pull roller 11 and on the free path between the pull roller 11 and the hopper inlet roller 12, the voltages S1; S2; S3; S4 of web B measured. This can take place, for example, via measuring rollers or the power consumption of the drive motors of the traction elements.

The starting point for the adjustment of the tension of the web B are, in particular if several webs B are combined at the funnel inlet at the funnel inlet by means of the funnel inlet roller 12, the absolute and relative tensions S4 of the individual webs B on the funnel inlet roller 12 with respect to one another (several webs indicated in FIG. 1) ). Accordingly, the tension of the web B is adjusted starting from the desired level on the hopper inlet roller 12. The basic level of the tension of the web B is preferably determined by adjustment on the feed mechanism 02. A change in the level for the tension of the web B is also advantageous This is done by changing the tension S2 at the infeed unit 02. To tension the web B, the first pull roller 03 is therefore operated with a lag compared to the machine speed. In continuous printing, ie at printing speed and with the addition of water and / or ink, the second drawing roller 11 is usually operated with an advance compared to the machine speed of the rotating cylinders 18, for example the transfer cylinders 18.

The pull rollers 03; 11 and the hopper infeed roller 12 and, if appropriate, drives located between the second pull roller 11 and the hopper infeed roller 12 can be regulated for speed, torque or rotational position for production printing. In particular, the pull roller 03 can be regulated in such a way that the tension S2 between the feed unit 02 and the first printing unit 06 is continuously returned to a desired value.

When running a dry web B, it is advantageous if the same tension S2 and S3 or S5 to S7 of web B prevail before the first printing group 06 and after the last printing group 09 and between the printing groups 06 to 09. When water and / or ink are switched on, the tension or elongation behavior and the conveying behavior of web B change during passage through the individual printing points of printing units 06 to 09.

A basic setting of the voltages S2 and S3 during continuous printing before the first printing unit 06 and after the last printing unit 09, as shown schematically in FIG. 2, is carried out using conventional control technology, for example via the web tension, speed or position-controlled pull roller 03, also the funnel feed roller 12 and / or dancer rollers, not shown, are produced. This tension-controlled state of the web B, with a retardation of the pull roller 03 and an advance of the pull roller 11 in relation to the machine speed, already takes account of a change in length of the web B, which gradually takes place during the passage through the printing units 06 to 09 due to the effects of moisture. Symmetrical and stationary fan-out designs in the cross register can also be taken into account here.

Even between the printing units 06 to 09, the conveying behavior and tension S5 to S7 of web B change when the printer is switched on and water and ink are added, when changing to a different paper type or when changing the process parameters such as adding the amount of dampening solution When the web B passes through a plurality of printing units 06 to 09, the paper properties can change significantly as the path T moves, which in turn results in a different conveying behavior of the web B as it runs through the printing units, for example 06 to 09. For example, depending on the type of paper and the free path between the printing units 06 to 09, the humidity is partly. even before reaching the third pressure point, e.g. B. here of the third printing unit 08, completely penetrated into the web B.

In order to counteract the changes or fluctuations in the conveying behavior and / or the changes in the voltages S5 to S7 of the web B during the passage through the printing units 06 to 09, a distance a between the two cylinders 18 each acting together via the web B is Printing unit 06, 07, 08, 09 changeable (Fig. 3). This can be done in such a way that a stop for the pressure-on position can be changed. The path B runs between the cylinders 18, which can be moved radially relative to one another at a distance a, and is clamped between them in the pressure-on position. The two cylinders 18, which can be changed relative to one another at a distance from each other, represent two transfer cylinders 18 in rubber-to-rubber printing. This change in the distance a, for example by a change Aa between the two cooperating transfer cylinders 18, preferably takes place in such a way that a distance b in each case between the transfer cylinder 18 and a cylinder 19 cooperating therewith, e.g. B. a forme cylinder 19 is preserved. Typically, the transfer on and down positions of the transfer 18 and forme cylinder 19 take place relative to one another by pivoting eccentric bushes which receive the pins of the transfer 18 and forme cylinder 19. The change in the distance a can take place, for example, by a second device, the change in the distance a not having to result in a change in the distance b. This can be achieved, for example, by a second eccentricity of the eccentric bushes receiving the pins. For this change, however, an existing paper thickness setting provided on the machine can also be used. With a suitable arrangement of the respective transfer cylinder 18 and forme cylinder 19 relative to one another, a linear displacement of one of the transfer cylinders 18 is also conceivable. Preferably, as indicated in FIG. 3, the change in the distance a takes place via the setting of a second eccentric bushing on one of the two cooperating transfer cylinders 18. The setting of the distance a, in the example the setting of the second eccentric bushing, takes place by means of an actuator 21, for example hydraulic, pneumatic, mechanical, electrical or in combination.

The described change in the conveying behavior by varying the distance a by a change Δ & takes place only in the area in which the web B is still clamped between the transfer cylinders 18, that is to say conveyed. This regulation of the tension of the web B and the conveying behavior therefore takes place in the pressure-on position of the cooperating transfer cylinders 18. A pressure gap d between the outer surfaces of the two transfer cylinders 18 interacting via the web B is in the pressure-on position in each phase less than or equal to the thickness of the web B at the corresponding location.

If there is now a change in the conveying behavior of web B on one or more printing units 06 to 09, a change in the distance a is possible, for example, by the value of the change Δ, which increases or decreases the Pressure gap d results. The setting of the actuator 21 and thus the change Δa of the distance a can be carried out by the operator himself, for example from a control station via a value for the change Δa transmitted to the actuator 21 as the control value Δa or on the printing unit by pressing an appropriate button. For example, the actuator 21 adjusts a stop against which the respective transfer cylinder 18 is placed in the print-on position. The operator can thus influence the conveying behavior of the web B between the printing units 06 to 09 during the production run, while production is running.

In a preferred embodiment, the control of the conveying behavior of the web B between the printing units 06 to 09 takes place automatically and is integrated, for example, in a control concept for the tension of the web B, which stresses and strains before the first printing unit 06 and after the last printing unit 09 for compensation of changes in web B stretch due to changes in paper properties.

The control of the conveying behavior of the web B in or between the printing units 06 to 09 is advantageously carried out using parameters of the drives 22. An actual value X-actual, a parameter X-actual _! is measured on the drive 22 in the printing unit i and with a setpoint X setpoint. compared. A deviation Δ is used for regulation and, if necessary, for changing the distance a between the cylinders 18. The drive 22 of the transfer cylinder 18 is preferably regulated to a constant peripheral speed or angular speed.

The regulation of the conveying behavior of the web B in or between the printing units 06 to 09 is preferably carried out via a power consumption P actual (for printing unit i) of the drives for the cylinders 18 interacting with the web B, in the example the transfer cylinder 18 Around the foot of the forme cylinder 19 and possibly with these mechanically coupled inking and / or dampening units (not shown) at the To keep the measurement of the power consumption as low as possible, the two transfer cylinders 18 per printing unit 06 to 09 are preferably driven in pairs by their own drives 22, and the form cylinders 19 interacting with them, together with the associated dyeing and, if appropriate, dampening units, are driven by their own drives 23. In an embodiment of the invention, each pair of transfer cylinders 18 is mechanically coupled, for example via gear wheels or belts. However, each transfer cylinder 18 can also be individually driven and electronically synchronized. A change in the voltage or the conveying behavior pulls a change in the power consumption P-actual at the preferably speed-controlled drives 22. after itself.

The power consumption P-Actual, by the drives 22 of a pair of cylinders 18 interacting with the web B, provided that it is standardized accordingly, is a measure of the work performed by the drive 22 per unit of time, which in turn is a measure of the conditions of the Voltages S2; S5; S6; S7; S3 before and after the cylinders 18 and for the conveying behavior of the web B. Correspondingly, setpoints P setpoint (printing unit i) for the consumption of the power of the drives 22 are defined for the successive printing units 06 to 09. As a rule, these are different from one another for the printing units 06 to 09 which are passed through one after the other in the transport direction T (FIG. 5). In the example, these target values P-target _{06 increase} from the first printing unit 06 with P-target ₀₆ approx. 4 kW to the fourth printing unit 09 with P-target ₀₉ approx. 7 kW. However, setpoints ΔP _J J -Soll in the power consumption of the differences ΔP _J J = P-Ist can also be used as setpoints. - P-actual _{j of} two successive printing units i and j, for example ΔP _{07 06} ⁼ 1 kW can be specified.

The current power consumption P-actual is compared with the respective target value P-target, or the differences ΔP _jj Tiit with the target value ΔP ,, - -set. If a deviation ^ or. Δ, _j From the setpoint P setpoint. or ΔP _J , -Soll measured, this is processed as shown schematically in Fig. 6, processed in the control loop and a change in the distance a by the value Δa effected via the actuator 21. This results in a larger or smaller printing gap d or rubber blanket protrusion between the two transfer cylinders 18 acting together and thus a changed conveying behavior of the web B in the printing unit i in question (with i from 06; 07; 08; 09). The changed conveying behavior of the web B now in turn changes the power consumption P-actual, the drive 22 of the i-th printing unit. This power consumption P-Islj is monitored and returned to the control loop.

To control the pressure gap d in the pressure-on position, d. H. if the web B is clamped between the transfer cylinders 18 and is thus conveyed, other suitable parameters from the drives 22 can also be used. Measured values for the voltage S5 to S7 between the printing units 06 to 09 can also be used to regulate the distance a or the printing gap d. However, the use of existing performance data is advantageous, since this requires little additional effort.

In the case of cylinders 18; 23 can the parameter z. B. be an angular velocity, which changes with changed voltages or conveying behavior. This change can now be counteracted again by changing the distance a.

If the transfer cylinder 18 does not interact via the web B with a second transfer cylinder 18, but with an impression cylinder 23 (FIG. 4), the transfer cylinder 18 is turned on the impression cylinder 23 via the web B to the impression cylinder 23 or vice versa , To change the voltages S5 to S7, the distance a between the transfer cylinder 18 and the cooperating counter-pressure cylinder 23 is changed. Both cylinders 18; 23, e.g. B. two blanket cylinders 18 or a blanket 18 and an impression cylinder 23, in order to change the distance a be moved. The described method also includes variants, wherein an impression cylinder 23 interacts with two or more transfer cylinders. Changes in the respective tension of the web B in the print-on position are made by varying the distance a between the impression cylinder 23 and the blanket cylinder 18.

The two cylinders 18; 23 can also be arranged elsewhere in a printing press, in a paper machine or in a rolling mill, for example in a coating device, a dryer, in the superstructure, a coating or rolling device, a calender or in other devices guiding a web B.

A change in the tension ratios or a change in the conveying behavior is determined via a characteristic variable characterizing the tension relationships. It can also have a size other than the power consumption P-Ist., Z. B. a change in angular velocity in the case of cylinders 18 controlled with a constant torque; 23, or a direct voltage measurement. The change in this variable represents a measure of the mutually influencing variables “tension” and “delivery behavior”. In particular, it shows a change in the ratios of the tension S2; S3; S5; S6; S7 of the web B before and after the printing units 06; 07; 08; 09 or a change in the resulting funding behavior. The deviation of the characteristic variable characterizing the tension relationships from the target value X target is now used to determine the distance a - which influences the conveying behavior of the web B - between the cylinders 18; 23 to change.

The printing units 06; 07; 08; 09 are thus at an approximately constant voltage S2; S3; S5; S6; S7 of the web B in front of, behind and / or between the printing units 06; 07; 08; 09 adjustable. LIST OF REFERENCE NUMBERS

01 reel changer

02 feed mechanism

03 pull roller

04 -

05 -

06 printing unit, first

07 printing unit, second

08 printing unit, third

09 printing unit, fourth

10 -

11 pull roller

12 funnel infeed roller

13 drive

14 drive

15 -

16 Drive control

17 Drive control

18 cylinders, transfer cylinders

19 cylinders, forme cylinders

20 -

21 actuator

22 drive

23 impression cylinders

B train; printing material; paper web

T direction of transport a distance (18) b distance (18, 19) d pressure gap

51 tension

52 tension

53 tension

54 tension

55 tension

56 tension

57 tension

Δa change, manipulated variable Λ _| Deviation ΔP, difference Δ _J J -setpoint

P actual, power consumption for printing unit i, with i = 06 to 09 P setpoint, setpoint for printing unit i, with i = 06 to 09

X-actual, actual value X-target, setpoint

Claims

Expectations

1. A method for regulating a voltage (S2; S3; S5; S6; S7) of a web (B), the web (B) between a cylinder pair interacting via the web (B) with a first cylinder (18) and one second cylinder (18; 23) is clamped, characterized in that for regulating the tension (S2; S3; S5; S6; S7) of the web (B) a change (Δa) in a distance (a) of the two cylinders (18; 23) takes place.

2. Method for regulating a voltage (S2; S3; S5; S6; S7) of a web (B), the web (B) between a cylinder pair interacting via the web (B) with a first cylinder (18) and one second cylinder (18; 23) is clamped, and an actual value (X-actual,) of a parameter characterizing the relationships of the tension of the web (B) before and after the cylinders (18; 23) is measured and compared with a target value (X-target ,) is compared, characterized in that on the basis of a deviation (Δ) of the measured actual value (X-actual,) from the target value (X-target,), a change (Δa) of a distance (a) together with the web (B) acting cylinder (18; 23).

3. The method according to claim 1, characterized in that the change (Δa) of the distance (a) of the cylinders (18; 23) interacting with the web (B) on the basis of a deviation (Δ,) of a measured actual value (X-actual .) from a desired value (X-Soll,) a characteristic variable characterizing the relationships of the tension of the web (B) before and after the cylinders (18; 23).

4. The method according to claim 2 or 3, characterized in that the two cylinders (18; 23) are driven by at least one drive (22).

5. The method according to claim 4, characterized in that the actual value (X-actual,) of the parameter on the drive (22) is determined.

6. The method according to any one of claims 1 or 2, characterized in that the first (18) and the second cylinder (18; 23) in a printing unit (06; 07; 08; 09) of a printing press, in particular a rotary printing press, is arranged.

7. The method according to claim 5, characterized in that a power consumption (P-actual,) of the drive (22) is recorded as the actual value (X-actual,) and a target value (P-target.) As the target value (X-target.) is specified for the power consumption.

8. The method according to claim 6, characterized in that the two cylinders (18) acting together with the web (B) are designed as transfer cylinders (18) and are driven by a common drive (22).

9. The method according to claim 8, characterized in that the transfer cylinders (18) each cooperate with a forme cylinder (19), and that this forme cylinder (19) is mechanically decoupled from the drive (22) of the transfer cylinder (18).

10. The method according to claim 6, characterized in that the first cylinder (18) is designed as a transfer cylinder (18) and the second cylinder (23) is designed as a counter-pressure cylinder (23) cooperating via the web (B), that the transfer cylinder (18 ) interacts with a forme cylinder (19) mechanically decoupled from the drive (22) of the transfer cylinder (18).

11. The method according to claim 10, characterized in that a change (Δa) of the distance (a) between the transfer cylinder (18) and the impression cylinder (23) takes place.

12. The method according to any one of claims 9 or 11, characterized in that when the distance (a) changes by the change (Δa), a distance (b) between the Transfer cylinder (18) and the form cylinder (19) interacting with it is kept almost constant.