EP0933201B1 - Drive control method for a paper web of a printing machine - Google Patents

Abstract

During operation the drive rotates at a certain speed v and produces a drive torque. The speed v is lowered or raised in dependence on the load torque according to a load characteristic line so that the drive simultaneously sets the target speed and drive moment or web tension. A guide ideal value such as a speed or position ideal value is compensated according to the load characteristic line. The dependence between the change in the load moment and the lowering or raising of the speed can be linear or non-linear.

Description

Technical field

The invention relates to the field of printing technology. It starts from one Method for controlling the drive for the transport of a paper web Printing machine according to the preamble of the first claim.

State of the art

The invention is particularly advantageous for shaftless rotary printing presses used. A shaftless rotary printing machine with pairs of cylinder groups summarized blanket and plate or form cylinders is in DE 43 44 896 A1. A method of operating a drive system which is particularly suitable for shaftless rotary printing machines DE 196 26 287 A1. The torque control is based on this procedure with a speed control (speed control) or position control (Angular position control) of the driven axes superimposed. Here are to control the individual drives for printing cylinders and folders in the for rotary printing presses Angular synchronous synchronism preferably uses position controls.

A major advantage of individually driven rotary printing machines is that these machines are able to change products while ongoing Machine. Such product changes include the arrival and departure Shutting down printing points and changing paper types while the machine is running, resulting in significant and impermissible changes in web tension can lead.

When operating drive groups controlled in this way - and especially then, if product changes are carried out while the machine is running or if paper type changes occur during ongoing production - undesirable side effects such as fluctuations can occur Web tensions and as a result e.g. to paper tears.

DE-A-35 19 840 discloses a method for controlling an electric motor on an offset printing machine. The engine is in normal operation with a constant speed, according to a predetermined speed setpoint, operated. In exceptional situations, if a certain engine temperature or a certain drive torque is exceeded, or if a mains voltage decreases, the speed setpoint is reduced.

EP-A-0 355 442 shows a method for reducing the torque load a drive. It is assumed that the load moment, at constant speed, changes cyclically. This is counteracted by in an initialization phase the load moment (possibly for different Velocities) measured during a period and depending the position is saved. This stored value is used during operation periodically subtracted from the drive torque setpoint. This turns it a speed which varies periodically by an average at which then the load torque remains approximately constant.

• sich der Papierzug zwischen dem Einzugswerk und dem Druckwerk beim Anfahren der Maschine nur sehr langsam aufbaut.
• die Bahnspannung im Normalbetrieb relativ stark schwankt.
• die Bahnspannung bei Änderung der Papiersorte oder des Produktionslaufes extrem stark schwankt, was auf die schlagartig veränderte Papierbahnlängen bei Druckanstellung bzw. Druckabstellung der Druckwerke zurückzuführen ist. Dies gilt sowohl für Bahnführungen über mehrere Drucktürme als auch für solche innerhalb eines Druckturmes, eines Wendeturmes oder des Falzapparates.
• die Bahnspannung bei Nothalt der Maschine nicht eingehalten wird.

The conventional methods for controlling the drive for the transport of a paper web mainly have two operating modes: The drives are controlled either at constant speed or at constant web tension. In one form or another, these methods have the disadvantage that:

• the paper draw between the feed unit and the printing unit builds up very slowly when the machine starts up.
• the web tension fluctuates relatively strongly in normal operation.
• the web tension fluctuates extremely when the paper type or production run is changed, which is due to the abruptly changed paper web lengths when the printing units are switched on or off. This applies to web guides over several printing towers as well as for those within a printing tower, a turning tower or the folder.
• the web tension is not maintained when the machine is stopped.

• sich einerseits die Papiereigenschaften der laufenden Bahn ändern und bei konstanter Drehzahlregelung zwangsläufig häufige und grosse Regelausgleichvorgänge durchzuführen sind und
• andererseits die Maschine hinsichtlich Regeldynamik solche Regelabweichungen nicht in der gewünschten Zeit auszugleichen vermag und zudem zu einem Schwingungsverhalten neigt.

All of these disadvantages are due to the fact that

• on the one hand, the paper properties of the running web change and, with constant speed control, frequent and large control compensation processes are inevitable and
• on the other hand, with regard to control dynamics, the machine is unable to compensate for such control deviations in the desired time and also tends to vibrate.

Presentation of the invention

The object of the invention is therefore a method for controlling the drive specify the paper web of a printing press in which the web tension in all possible operating modes of the rotary printing press, with or without changing the paper type or the content of the printed product while running Machine shows no significant fluctuations and deviations be quickly compensated. This task is characterized by the characteristics of the first Claim solved.

The essence of the invention is that the regulation of the drives of the paper web e.g. in the pretensioners or the turning towers of a rotary printing press both Speed and web tension are taken into account flexibly. So that becomes a significantly better paper guidance with controlled web tension both in allows static as well as dynamic operation. In the simplest case this is achieved by setting the speed controller so that this one significant dependence of the drive torque on the deviation between Shows target and actual speed. This controller deviation is taken into account in the master setpoint and thus set a suitable working point. With production-related Varying the machine configuration shifts the current working point along a curve (load curve), whereby both the actual speed value as well as the drive torque can be changed. The slope of this Curve is a measure of the influence of the load change on speed and torque. It is preferably chosen so that the drive torque and thus the web tension is kept within the operating limits. The The master setpoint largely determines the static and dynamic management behavior.

A distinction can be made between pre-controlled and regulated operation. In the simpler case of pre-controlled operation (open loop), known ones are made Influences of the process to be controlled are taken into account. In one The first step will be stationary operation as well as acceleration-dependent Sizes preset. In optional regulated operation (closed loop), for example, the web tension is measured; it works through you Control algorithm on the master setpoint. This is a regulation of Guaranteed residual errors.

• Im vorgesteuerten Betrieb wird bereits eine hohe statische Genauigkeit der Bahnspannung erreicht, die eine geringe Sensibilität auf Störgrössen aufweist.
• Da die oben beschriebene Belastungskurve Teil des Drehzahlreglers ist, weist das Verhalten eine extrem hohe Dynamik auf. Damit sind charakteristische Reaktionszeiten von unter 1 Millisekunde möglich. Dieses ist bedeutend rascher als bei konventioneller Bahnspannungsregelung.
• Weiters führt die Belastungskurve zu einer Dämpfung von mechanischen Schwingungen. Diese Eigenschaft ist vor allem bei mechanischen Anregungen, wie sie bei Änderung der Papiersorte oder des Produktionslaufes auftreten, wichtig.

In comparison to the operation according to the state of the art, there are significant advantages:

• In the pre-controlled operation, a high static accuracy of the web tension is achieved, which has a low sensitivity to disturbance variables.
• Since the load curve described above is part of the speed controller, the behavior is extremely dynamic. Characteristic response times of less than 1 millisecond are possible. This is significantly faster than with conventional web tension control.
• Furthermore, the load curve leads to damping of mechanical vibrations. This property is particularly important for mechanical stimuli, such as those that occur when changing the paper type or the production run.

Further advantageous embodiments result from the corresponding dependent claims.

Brief description of the drawings

Fig. 1

Eine schematische Darstellung der Rotationsdruckmaschine mit den die Bahnspannung beeinflussenden Elementen

Fig 2

Eine schematische Darstellung des Reglers für das elektrische Vorspannwerk einer Rotationsdruckmaschine

Fig. 3

Ein Diagramm zur Darstellung der Abhängigkeiten zwischen Bahnspannung und Drehzahl bei unterschiedlichen Papiersorten bzw. Produktionsläufen

The invention is explained in more detail below on the basis of exemplary embodiments in conjunction with the drawings. Show it:

Fig. 1

A schematic representation of the rotary printing press with the elements influencing the web tension

Fig. 2

A schematic representation of the controller for the electrical leader of a rotary printing press

Fig. 3

A diagram showing the dependencies between web tension and speed for different types of paper or production runs

The reference symbols used in the drawings and their meaning are in the list of reference symbols is summarized. Basically are in the figures Identical parts with the same reference numerals.

Ways of Carrying Out the Invention

Figure 1 shows a schematic representation of the rotary printing press with the elements influencing the web tension. The paper guide or paper web is the web that describes the paper to be printed from the roll change (1) via the pendulum roller (2) and the electrical pretensioner (3), via any combination of printing units in the printing tower (5) or in several printing towers , through the turning tower (6), collecting roller (7), hopper inlet roller (8) to the folder (9). The web tension of the paper web is set on the electrical pretensioner (3) via the drive (M) and the controller (4). The specified limit values must not be exceeded or undershot. If a paper type is changed on the reel changer (1) while the machine is running, the web tension changes suddenly due to the changed paper properties (case 1). If the printing tower is equipped with individually driven printing units or pressure bridges, the production run can be changed while the machine is running. Such product changes include starting or stopping the printing units required for the two production runs. The paper web is temporarily and partially exposed during this process. As a result, the web tension of the paper web varies considerably (case 2). Both cases give rise to the present invention in order to compensate for the web tension changes within a very short time and to keep them within the permissible limit values.

In the following the method according to the invention is based on the drive control of a pretensioner explained. Of course, the procedure but can be used wherever the paper web is driven must, i.e. especially in the turning towers.

Figure 2 shows a control device for the electrical pretensioner (3), which is suitable for the inventive method. The master setpoint is formed in the setpoint generator (10). Depending on the application of the control method, a speed or a position can be used as the reference setpoint. In the controlled embodiment according to FIG. 2, a difference between the master setpoint and the web tension actual value (13), which is measured on the paper web in the pretensioner (3), is formed in the setpoint generator (10). This variable serves as a reference variable for the downstream drive controller (11). In the unregulated case, the master setpoint is passed on directly as a command variable. The drive controller (11) has a so-called droop behavior, ie it enables the load-dependent speed reduction or increase according to the invention. An actual drive value is measured in the controller (11) - normally a position or a speed - compared with the reference variable and a resulting control deviation is formed. The manipulated variable is fed to the motor converter, not shown, in such a way that the motor is controlled as desired.

The behavior of the controller (11) according to the invention is explained in more detail below with the aid of FIG. 3 on the basis of the various operating cases and the web tension-speed characteristic curves according to the invention. The axis of abscissa shows the engine speed (v), which is usually given in cylinder revolutions per hour. The paper tension (F) is entered in the ordinate axis. This is usually related to the respective paper width and specified in daN / m. The droop is the property of the device (11) with which a load-dependent reduction or increase in the speed setpoint is effected.

The starting point in the diagram is the production speed (v _P ). A conventional position or speed-controlled pretensioner is operated with a lag (p1), which results in its load curve (F _A1 ). On the other hand, the paper spinning of paper type 1 or of production run 1 increases with increasing lag (p1) of the leader. The web tension therefore runs according to (F _P1 ). The resulting working point is at the intersection (A) of the two curves. When changing the paper type or the production run, the characteristic curve can change. When changing the characteristic from (F _P1 ) to (F _P2 ), the operating point changes from (A) to (B). With a speed control according to the load curve F _A1 , the speed V _{A is} kept constant even with changes in load torque. This results in an impermissible change in the paper tension by the amount dF ₁ = F _A - F _B.

This impermissible operating state is avoided with the method according to the invention by the load curve (F _A2 ). The lag of the master setpoint (p2) is significantly greater here. Starting from paper type 1 or from production run 1, the operating point (A) with speed (v _A ) and paper tension (F _A ) is set. A change of paper type or production run to the characteristic (F _P2 ) now leads to the new working point (C). This includes both a changed paper tension (F _C ) and a changed speed (v _C ). The drive therefore responds to the change in the process variables with both status variables (v and F). Not only is the web tension F (or the drive torque) tracked, but the speed is also increased or decreased in accordance with the change in load. The relationship between speed change and load change can be linear or non-linear. The resulting change in paper tension (dF2) is significantly less due to the influence of the method according to the invention, or it can even be practically avoided entirely. This is at the expense of the speed (v), but this has no influence on the product quality.

The control method according to the invention was described above using the prestressing mechanism explained. However, it can be used wherever a paper web must be driven in a printing press, i.e. especially also in the turning towers. The advantage of the method according to the invention lies specifically in the fact that there are no impermissible web tension changes when the load changes during operation occur that overstress the paper web during transport.

LIST OF REFERENCE NUMBERS

1

reelstands

2

Spherical roller

3

Electrical pre-tensioner

4

Regulator for pretensioner

5

Printing tower or printing towers with individually driven printing units or pressure bridges

6

turning tower

7

collection roller

8th

Former inlet roller

9

folding

10

master set point

11

Drive controller with droop behavior

12

Antriebsistwert

13

Bahnspannungsistwert

M

drive motor

F

Web tension of the paper web

v

Machine speed

F _A1

Load curve without droop

F _A2

Load curve with droop

P _P1

Characteristic curve of paper type 1 or production run 1

F _P2

Characteristic curve of paper type 2 or production run 2

F _A

Web tension at working point A

F _B

Web tension at working point B

Fc

Web tension at operating point C

dF1

Web tension deviation without droop

dF2

Web tension deviation with droop

V _A

Speed at operating point A

vc

Speed at operating point C

v _P

Production speed

p1

Drive lagging to production speed without droop

p2

Drive lagging to production speed with Droop

A

Specified operating point with characteristic curve Fp ₁

B

Resulting working point when changing from F _P1 to F _P2 without droop

C

Resulting working point when changing from F _P1 to F _P2 with Droop

Claims (4)

1. Method of controlling the drive for transporting a paper web in a printing machine, the drive, when operating, rotating at a specific speed v and producing a drive torque or a web tension, the speed v being lowered or raised as a function of a load torque occuring at the time and in accordance with a loading characteristic, so that the drive simultaneously sets the target variables of speed and drive torque or web tension, and a reference desired value, in particular in the form of a speed or position desired value, being compensated for in accordance with the loading characteristic characterized in that in the case of such a shift in operating point, both the actual speed value and the drive torque are charged.
2. Method according to Claim 1, characterized in that the dependent relationship between the change in load torque and the lowering or raising of the speed is linear.
3. Method according to Claim 1, characterized in that the dependent relationship between the change in load torque and the lowering or raising of the speed is nonlinear.
4. Method according to Claim 1, characterized in that the dependent relationship between the change in load torque and the lowering or raising of the speed is a function of time.

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