EP1303404B1 - Method for regulation of a web tension in a rotary print machine - Google Patents

Abstract

Tension of a web in a rotary printing press is regulated. The web passes through at least two printing groups in the printing press. A change in the extension of the web during the print run is determined based on a phase shift between a first phase position of a printing group and a second phase positioned measured after a last printing group. The change in phase position is compensated for by a change in the web tension prior to the first printing group.

Description

The invention relates to a method for regulating a web tension in a rotary printing press according to the preamble of claim 1.

By the EP 09 51 993 A1 a register-containing drive for a rotary printing machine is known, wherein a longitudinal expansion of the Bedruckbahn determined from Bahnspannungs- and operating values of the drives, and is compensated by adjusting the circumferential register on the cylinders and the register rollers. A transverse strain change determined via a sensor for web width detection is fed back via a correction quantity to the desired value of the tension roller controlled on web tension constancy.

In the US 3,025,791 A discloses a method for controlling the drives of a printing machine with the aim of a constant elongation. The measurement of the elongation takes place here near the first printing unit by comparing the angular position of the printing unit and subsequently the position of a mark on the printing material. A change in the relative position causes a voltage change for the printing material web in the intake mechanism.

The DE 92 18 978 U1 discloses a first control loop wherein a voltage between a printing couple and a tension roller is controlled to be constant. In a second control loop is controlled by means of a rotational position of the printing unit and the cutting cylinder and an optical signal which processes the position of a brand, via the drive of the cutting cylinder, an angular position of the cutting cylinder.

The invention has for its object to provide a method for controlling a web tension in a rotary printing press.

The object is achieved by the features of claim 1.

The advantages that can be achieved with the invention are in particular that fluctuations or changes in the elongation during ongoing production, d. H. be measured during the printing in a simple manner, and this measurement is used to control the arranged before the first printing unit retraction.

In particular, the measurement as possible after the last printing unit, gives the greatest possible information about the operating condition of the web before entering the superstructure, in particular the funnel inlet.

With the addition of water and / or color, the tension / elongation behavior of the web changes as the web passes through the pressure points and causes, for example, an increase in the elongation after the last printing unit. However, in order to ensure a smooth funnel inlet of the webs in multi-lane operation is achieved in order to achieve the necessary gradation in the web tension after switching on water and color as possible only about adjustment of the infeed the appropriate web tension level of the tracks to each other.

The paper web expands under the influence of the fountain solution and / or the color both in the longitudinal and in the transverse direction with respect to the transport direction. This is reflected, in particular in multi-color printing with free path lengths between adjacent pressure points as elongation of the web. This elongation, as long as the effect at each pressure point remains constant over time, at least in part, for example, be compensated by register adjustment on the cylinders, by changing the position of register rollers or other facilities.

However, the stretching behavior of the paper web is subject to many influences such as Example of the stress / strain characteristics of the paper and thus the prevailing voltage, the current humidity, the moisture sensitivity, the penetration, the position of the role in their production in the drum, which is reflected for example in different winding hardness, or a location-dependent variation in Modulus of elasticity.

The elongation, both the longitudinal and the transverse strain, is therefore not stationary because of non-constant paper properties of the rolling paper web itself and because of changing and sometimes fluctuating operating parameters on the printing press. On the other hand, a fluctuating web tension, changing printing speed, fluctuation in the moistening or a change of the roll affect the stretch of the paper web, so that the stretching is not stationary in time.

Advantageously, with the aid of the method according to the invention, changes or fluctuations in the elongation, in particular in the longitudinal expansion in the transport direction, can be compensated.

It is also advantageous to determine the strain change at the end of a printing tower or the last printing unit in the transport direction, since this provides a good information about the entire change for the further processing steps and a countermeasure, if desired in the sense of a constant voltage or, as preferred here a constant stretching of the web for the subsequent paths of the web or processing steps allows. In this sense, it is also advantageous that the control is not in the field of measurement, but at the beginning of the web, whereby a level of web tension or a resulting input stretch is set and subsequently controlled without major changes in the superstructure, especially in front of the funnel feed roller to induce web tension and / or elongation.

In particular, by determining the strain change behind the last Printing unit and appropriate control of the input stretch to ensure that the number and the exact phases of the printed images between the last printing unit or the last printing location and, for example, a folder is constant, which is complicated or difficult to adjust by adjusting individual registers. The process thus makes at least part of a continuous readjustment of the cut register of a web over all drives of the printing units or register rollers during ongoing production at least partially unnecessary.

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

Fig. 1

eine schematische Darstellung für die Führung einer Bahn vom Einzugswerk über vier Druckwerke und eine zweite Zugwalze bis hin zu einer Trichtereinlaufwalze;

Fig. 2

eine schematische Darstellung der Bahnspannungsniveaus im Fortdruck.

Show it:

Fig. 1

a schematic representation of the leadership of a train from the infeed over four printing units and a second draw roller to a funnel inlet roller;

Fig. 2

a schematic representation of the web tension levels in the production.

Fig. 1 shows schematically the course of a web B, z. B. a printing material 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 paster 01 via a retraction 02 with a tension roller 03 through the example four printing units 06 to 09 to a second draw roller 11. After the second draw roller 11, for example, turning bars, not shown, cutting knife, more train or guide rollers and ultimately follow a funnel inlet roller 12. The main draw rollers 03; 11 are in an advantageous embodiment, each with its own drive 13; 14 and a drive control 16; 17 equipped. Before the infeed 02, between the infeed 02 and the first printing unit 06 and between the last printing unit 09 and the draw roller 11 and on the free path between the tension roller 11 and the funnel inlet roller 12, stresses S1, S2, S3 and S4 of the track B are measured in a preferred embodiment. This can be done for example via measuring rollers or the power consumption of the drive motors of the tension members.

Starting point for the adjustment of the tensions of a web B are, in particular when multiple webs B are combined in multi-pass operation at the funnel inlet by means of the funnel inlet roller 12, the absolute and relative stresses S4 of the individual webs B to the funnel inlet roller 12 to each other. Accordingly, the adjustment of the tension of the web B is carried out starting from the desired level of the tension S4 at the hopper inlet roller 12. Preferably, the level of the total tension of the web B is determined by adjustment at the infeed 02. Normally, a change in the tension of the web B during the printing progress is advantageously effected by a change in the voltage S2 at the retraction 02. A basic setting of the voltages in the continuous printing, as shown schematically in Fig. 2, for example, on the web tension, speed - or position-controlled tension roller 03, the also controlled hopper feed roller 12 and / or dancer rollers not shown produced.

As a result of the stresses and, in particular during the printing, as a result of moisture, the web B is subject on its way from the infeed 02 to the draw roller 11 behind the last printing unit 09 longitudinal expansions of the web B with an input strain ε1 and an elongation ε after the last printing unit 09th When passing through the web B of four printing units 06 to 09 ε2 represents an expansion between the first printing unit 06 and second printing unit 07, ε3 an expansion between the second printing unit 07 and third printing unit 08 and ε4 an expansion between printing unit 08 and printing unit 09.

This usually in the continuous printing, ie at printing speed and with the addition of water and / or color, voltage-controlled state of the web B considered with a Lagging of the tension roller 03 and an advance of the tension roller 11 with respect to the machine speed already an elongation of the web B, resulting from the printing process and the effects of moisture.

The determination of the machine speed and / or the phase position of the machine can at the printing units 06; 07; 08; 09 done in various ways. For example, if each of the printing units 06; 07; 08; 09 is driven specifically, the performance data, the rotational angle positions or other characteristics of all or individual printing units 06; 07; 08; 09 are used.

In the exemplary embodiment, a phase angle φ1 of the first printing unit 06 is measured via a first sensor 18. This phase position φ1 can z. B. on a motor shaft of a drive 19 for a cylinder 21; in particular a drive 19 of a forme cylinder 21 of the printing unit 06, for example by means of an encoder, are tapped (shown in broken lines in Fig. 1). When the forme cylinder 21 is coupled to a cooperating cylinder 22, in particular a transfer cylinder 22, the phase position φ1 on the transfer cylinder 22 can also be determined. As shown in FIG. 1, the arrangement of a mark 23 as a reference point 23 on the forme cylinder 21 or on the transfer cylinder 22 together with a first sensor 18 for determining the phase position φ1 or a position φ1 can also be used. This can be done for example by a scanner or a photocell. Also, a brand applied by the printing unit 06 brand 23, a part of the printed image itself, a perforation or other markings on the web B can serve as a brand 23 for determining the first phase φ1.

In the transport direction T, a further sensor 24 is arranged after the last printing unit, here the fourth printing unit 09. By means of this second sensor 24, a second phase position φ2 or position φ2 of a mark 26 or at least a part 26 of a printed image of a printed web B is measured. The mark 26 can also be a perforation the web B or an equivalent-acting mark on the web B. Phase position φ2 of the mark 26 is understood here as the time sequence of the passage of the mark 26 at the detector. If the determination of the phase position φ1 takes place via a mark 23 arranged on the web B (as mentioned as an alternative), the mark 23, which in this case is identical, can be used as mark 26 to determine the phase position φ2.

When running the web B, the phase angle φ1 of the printing unit 06 is now determined by measuring the passage of the mark 23 first. After the last printing unit 09, after passing through the printing units 06 to 09, the second phase angle φ2 of the mark 26 printed on the web B or the part of the printed image 26 is determined. Taking into account a fixed position of the measuring points to one another, a fixed phase shift Δφ would then be detectable over a constant distance ε of the path B over a constant time span. This is where the method for controlling a web tension in a rotary printing machine, since the elongation ε of the web B from o. Reasons during production is not constant over time.

The value for the phase shift Δφ, which is determined, for example, at the beginning of the printing run and after the desired voltages S1 to S4 have been reached, is recorded as the desired value Δφ-Soll, for example in a memory unit. The target value Δφ-Soll can vary from production to production since it depends on the register status of the printing units 06 to 09. However, it should only be specified during stationary and trouble-free operation. The setting of the register level and the voltages S1 to S4 are as already shown in their basic setting i.d.R. already before the start of production, tailored to the paper properties, the web run and other o. g. Parameter takes place.

About the changes occurring during the printing Δε or fluctuations in The strain ε now delivers a deviation Δ of the actual value Δφ from the target value Δφ-Soll the information.

In order to change Δε or variations in the elongation ε, in particular changes Δε in the section length between the last printing unit and the further processing in the fold, as a result of o. G. To counteract reasons, the phase positions φ1 and φ2 and thus the phase shift Δφ are determined and compared with the desired value Δφ-Soll. Occurs during the printing of the current production as a result of one of the o. G. If the deviation .DELTA. In the difference .DELTA..phi. From the target value .DELTA..phi.-setpoint is due, this is an indication of a change Δφ in the elongation .epsilon.

If the phase shift Δφ is defined as a difference Δφ = φ2 -φ1, for example, an increase in the strain ε by Δε causes, for example, a deviation Δ of the phase shift Δφ from the nominal value Δφ-Soll.

This deviation Δ, and thus also the change Δε in the strain ε, is now compensated by the retraction gear 02 upstream of the first printing unit 06 via the change in the input strain ε1 until the desired value Δφ-set for the phase shift Δφ is restored. So that a swinging or an uneven web run of the web B is reduced or avoided, the control can also allow certain tolerances in the deviation of the phase shift Δφ from the target value Δφ setpoint before the countermeasure of a change in the input strain ε1 is taken.

The deviation .DELTA. From the nominal value .DELTA..phi.-setpoint can be superimposed, for example, as a disturbance variable .DELTA. The drive control 16 of the tension roller 03 can be regulated, for example, with respect to the torque, wherein a return of the voltage S2 takes place. A path of the web B via a corresponding measuring roller 27 for the measurement of the voltage S2 of the web B is dash-dotted in Fig.-1 shown. The setpoint generator of the drive control system 16 is superimposed with the deviation Δ from the reference value Δφ-desired disturbance variable Δ, for example as a correction variable ΔS 2. Such a correction quantity .DELTA.S2 can for example be taken from a stored curve for the dependence of .DELTA.S2 over .DELTA. Or iteratively carried out by increasing or decreasing the voltage S2 until the phase shift .DELTA..phi. Again corresponds to the desired value .DELTA..phi.-setpoint.

If abrupt changes in the action of force on the web B are to be avoided, it is also possible to use a drive control with DROOP behavior for the draw roller 03. As DROOP behavior, a load-dependent change of the setpoint value of a circumferential or angular speed or speed is called, which is both a change in the voltage of the web B, z. B. S4, as well as a change in the angular velocity considered. Also in this case, for example, the target value S2-Soll for the voltage S2, a correction amount superimposed ΔS2, which together with the actual value of the voltage S2 based on the DROOP function a corresponding lag of the draw roller 03, and thereby another voltage S2 and resulting input strain ε1 results, which is ultimately reflected as a change in the strain ε.

Regardless of the manner of the control for the tension roller 03 or the retraction 02, it is essential that the target value Δφ-set for the drive control 16 a determined from the phase shift Δφ and the target value Δφ-target disturbance Δ, for example, as a correction amount .DELTA.S2 of desired voltage S2, is superimposed. If necessary, the phase position φ1 can also be determined at one of the following printing units 07 to 09 instead of the first printing unit 06 in the transport direction T. The phase shift Δφ is then to be determined between the relevant printing unit 06 to 09 and the passage of the mark 23 on the sensor 24. The deviation .DELTA. Of the phase shift .DELTA..phi. From the desired value .DELTA..phi.-setpoint is again referred to as a disturbance variable .DELTA the tension roller 03 processed.

Synonymous with the determination of the phase positions φ1 and φ2 and thus the phase shift Δφ from the target value Δφ-set for the determination of the disturbance Δ also the temporal change of the phase shift Δ̇φ or, if the disturbance Δ determined linearly from the difference of the phase positions φ1 and φ2 is also the change in the difference in the temporal change of the phase angles Δφ̇ = φ̇2 - φ̇1 be used. Δφ̇ is then in normal operation ≅ 0.

With the disturbance variable Δ, the correction variable ΔS2 can also be changed as a voltage change ΔS2 in a different way than at the draw roller 03. The change in the voltage S2 by the disturbance Δ also includes changes in the action of force by a dancer roller, not shown, or other adjusting devices for the voltage S2 arranged in front of the first printing unit 06.

Advantageously, there is no direct feedback of a strain change Δε determined after the last printing unit 09 to the drive control 17 of the draw roller 11 arranged after the last printing unit 09, but rather a change in the input strain ε1 due to a change in the voltage S2.

When changing Δε the strain ε thus occurs a deviation Δ of the relative phase angle Δφ from the target value Δφ-Soll between a first measuring point by means of the sensor 18, the phase position φ1 of the transfer cylinder 21, and the second measuring point by means of the sensor 24, the position of the mark 23rd on the printed web B after passing through the printing units 06 to 09, a. This deviation Δ enters as an absolute value or as a signed value as a disturbance variable Δ for the regulation of the voltage S2 before the first printing unit 06. By this procedure is guaranteed that for subsequent operations, such as folding or cutting, a constant number of print images between the tension roller 11 and the subsequent processing step are located, and that the frequency of the passage of the printed images on the tension roller 11 is kept almost constant.

In favor of a constant section length or elongation ε after the last printing unit 09, if necessary, a variation in the voltage S2 before the first printing unit 02 is accepted. However, in each case the voltage S2 moves within a window for the permissible voltage and for the resulting voltage S4 with regard to the gradation in the multi-track mode.

LIST OF REFERENCE NUMBERS

01

reelstands

02

infeed

03

pulling roller

04

-

05

-

06

Printing unit, first

07

Printing unit, second

08

Printing unit, third

09

Printing; fourth

10

-

11

pulling roller

12

Former inlet roller

13

drive

14

drive

15

-

16

drive control

17

drive control

18

Sensor, first

19

drive

20

-

21

Cylinder; form cylinder

22

Cylinder; transfer cylinder

23

Brand, reference point (21)

24

Sensor, second

25

-

26

Brand, part of the printed image

27

measuring roll

φ1

Phase position, position

φ2

Phase position, position

Δφ

phase shift

Δφ target

setpoint

.DELTA..phi

temporal change of the phase shift

.DELTA..phi

Change of the difference in the temporal change of the phase positions

.PHI.1

temporal change of the phase position

.PHI.2

temporal change of the phase position

Δ

Deviation, disturbance

ε1

input expansion

ε2

Elongation (06; 07)

ε3

Elongation (07; 08)

ε4

Elongation (08; 09)

ε

strain

Δε

Change of elongation (ε)

S1

tension

S2

tension

S3

tension

S4

tension

.DELTA.S2

correction variable

S2 target

setpoint

B

Web, substrate web, paper web

T

transport direction

Claims (14)

1. A method of regulating the tensioning of a web in a rotary printing press, wherein a web (B) runs through at least two printing couples (06; 07; 08; 09), and a first phase position (φ1) of one of the printing couples (06; 07; 08; 09) and a second phase position (φ2) measured downstream of one of the printing couples (06; 07; 08; 09) in the conveying direction (T) is determined, characterized in that the second phase position (φ2) is determined downstream of the last printing couple (09) in the conveying direction (T) and a tension (S2) of the web (B) upstream of the first of the printing couples (06; 07; 08; 09) is altered in a manner dependent upon the said phase positions (φ1, φ2).
2. A method according to Claim 1, characterized in that the second phase position (φ2) is determined at a mark (26) present on the web (B).
3. A method according to Claim 1, characterized in that the tension (S2) is altered in order to change the incoming tensioning (ε1).
4. A method according to Claim 1, characterized in that the tension (S2) is altered as a result of a deviation (Δ) of an actual value of a phase displacement (Δφ) from a nominal value (Δφ-Soll).
5. A method according to any one of Claims 2 to 4, characterized in that

   - a first sensor (18) determines the first phase position (φ1) of the printing couple (06; 07; 08; 09) on a cylinder (21; 22),

   - a second sensor (24) arranged downstream of the last printing couple (09) in the conveying direction (T) determines the second phase position (ϕ2) of the mark (26) printed on the web (B).

   - the actual value of the phase displacement (Δϕ) is determined by means of the two phase positions (φ1, φ2),

   - the nominal value (Δϕ-Soll) for the phase displacement (Δϕ) is set in the stationary and interference-free operation, and

   - the change in the tension (S2) of the web (B) and thus in an incoming tensioning (ε1) of the web (B) is carried out upstream of the first printing couple (06) in the event of a tolerance - to be determined - of the nominal value (Δϕ-Soll) being exceeded or not being reached by the phase displacement (Δϕ).
6. A method according to Claim 1, characterized in that the change in the tension (S2) takes place in such a way that the phase displacement (Δφ) is set back to the nominal value (Δφ-Soll).
7. A method according to Claim 1, characterized in that the regulation of the tension (S2) takes place provided that a number of the print images on the web (B) is kept constant between the last printing couple (09) and a following treatment stage.
8. A method according to Claim 4, characterized in that the actual value of the phase displacement (Δφ) is compared with the nominal value (Δφ-Soll) during the production run, and the deviation (Δ) of the phase displacement (Δφ) from the nominal value (Δφ-Soll) is used as an interference variable (Δ) in order to regulate an infeed unit (02).
9. A method according to Claim 5, characterized in that the first phase position (φ1) on the cylinder (21; 22) is determined by the first sensor (18) with reference to a reference point (23) situated on the cylinder (21; 22).
10. A method according to Claim 5, characterized in that the cylinder (21) is a forme cylinder (21).
11. A method according to Claim 1, characterized in that the first phase position (φ1) is determined on the first printing couple (06) in the conveying direction (T).
12. A method according to Claim 2, characterized in that at least part of the print image (26) is used as the mark (26) for determining the second phase position (φ2).
13. A method according to Claim 1, characterized in that the interference variable (Δ) is supplied to a drive-regulation means (16) of a draw roller (03) arranged upstream of the first printing couple (06).
14. A method according to Claim 8, characterized in that the interference variable (Δ) is supplied as a correction variable (ΔS2) to a nominal value (S2-Soll) for the tension (S2) between the infeed unit (02) and the first printing couple (06).

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