EP1739042A1 - Method of operating a web processing machine - Google Patents

Abstract

A method for operating a continuous sheet-processing machine with an array of process elements and drive units (11) for the transport and/or processing of continuous sheet material, in which the speeds of at least some of the drives (11) are modulated with a preset modulation frequency and process variables for the machine are determined by measuring changes in the influencing variables for the drives (11) caused by the modulations.

Description

The invention relates to a method for operating a web-processing machine according to the preamble of claim 1.

Such web-processing machines generally have an arrangement of process elements with associated drives, wherein the process elements are used for the transport and / or processing of a web. Examples of such web-processing machines are in particular printing presses or other machines for the production or processing of webs formed from paper, cardboard or even plastics or textiles.

To control the operation of such web-processing machines, it is particularly necessary to obtain sufficient knowledge about the state of the web to be processed and the transport elements for the web. In particular, to ensure a consistently high quality of the processing of the web, it is necessary to obtain knowledge of the forces prevailing in the web and, as a result, the stretching of the web during the transport and / or machining processes carried out, as well as the slip and other unwinding properties of the transport elements ,

Such process variables in web-processing machines can be detected, for example, by the use of additional sensors. With such sensors, so-called web tension meters, the forces acting in a web can be determined. However, in order to precisely track the forces acting in the web, one must at different measuring locations Variety of such sensors are installed, which means a considerable installation and cost. In addition, it is often not possible for reasons of space or process-technical reasons to attach such sensors to web-processing machines.

In principle, a measurement of the torques of the drives can also be carried out to determine the stresses within the material web, for which purpose the motor currents in the individual drives can be measured.

The disadvantage here, however, is that such measurements involve a number of systematic and stochastic errors. A first source of error is that the necessary conversion of the determined motor current of a drive to the desired torque due to interference such as temperature effects, in principle, is faulty. Furthermore, this measured variable also includes friction moments or friction forces in the process elements. Thus, the measurement of the motor current as a parameter for the torque of a drive provides no reliable, reproducible statement about the process size of the web.

The invention has for its object to provide a method of the type mentioned, by means of which with little design effort a reproducible control of the transport and / or processing of a web in a web-processing machine is made possible.

To solve this problem, the features of claim 1 are provided.
Advantageous Ausflihrungsformen and expedient developments of the invention are described in the subclaims.

The invention relates to a method for operating a web-processing machine which has an arrangement of drive-driven process elements for the transport and / or processing of a web. The speeds of at least a part of the drives are each with modulated a predetermined modulation frequency. In order to determine process variables of the web-processing machine, changes in the influencing variables of the drives due to the modulations are recorded.

The basic idea of the invention is that, by the modulation of the speeds of the drives and the measurement of the respective influencing variable following the modulation frequency, it is possible to systematically eliminate external interferences in the measurement such as noise. It is essential here that the measurement of the respective process variable takes place exactly in the frequency and phase position of the modulation carried out. Thus process variables or web-processing machines can be detected accurately and reproducibly with the method according to the invention, whereby a reliable control of the operation of the web-processing machine is made possible.

Particularly advantageously, the speed modulation of the drives is performed such that the functions of the process elements remain unaffected, that is, the accuracy of the transport and / or the processing of the web remains within predetermined limits. For this purpose, the amplitudes and the modulation frequency of the modulation frequency carried out are to be selected in a suitable manner. The amplitude of the modulation is to be chosen sufficiently small compared to the absolute amount of the speed to be modulated. In particular, the modulation frequency is to be chosen so that the influencing variable to be measured can also follow the change in the speed due to the modulation, so that a measurable change in the influencing variable is produced. Thus, the detection of the process variable can be carried out without negatively affecting the operation of the web-processing machine. The accuracy of the measuring method according to the invention can thereby be further increased by repeating the speed modulations at predetermined time intervals and by integrating the results obtained for the influencing variable in the individual modulations.

The influencing variables detected in the method according to the invention are formed by characteristics of the drives, in particular the torques of the drives. In addition, if necessary, the positions and / or speeds of the drives can be detected.

A significant advantage of the method according to the invention is that these influencing variables can be detected without additional sensors. To record the influencing variables, already existing units can be used in the drives or in converters that are used to control the drives. In particular, the converters already have units for measuring the motor currents of the drives, which form a measure of the torques of the drives to be determined.

On the other hand, the inventive method can also be used for systems with additional sensors, in which case the signals form the measured influencing variables.

With the method according to the invention, information about different process variables can be obtained. This includes, on the one hand, information about the speed-dependent friction within the system, in particular the process elements driven by the drives. Furthermore, information about the material webs to be transported or processed can be obtained as further process variables. These include forces acting on the webs or reactions of the webs on such forces, in particular tensions in webs, deformations of webs and the resulting information about the elasticity of webs.

According to a first variant of the method according to the invention, the speeds of all drives of the web-processing machine are preferably modulated with a modulation frequency, wherein the torques of all drives are detected as influencing variables. In doing so, in particular Received information about the speed-dependent friction within the web-processing machine.

According to a second variant of the method according to the invention, speed modulations are not performed on all but on individual drives or individual groups of drives. In this case, the torques of all drives are preferably detected again as influencing variables. In addition, the positions and / or speeds of drives may be detected, preferably detecting the positions and / or speeds of drives whose speed has not been modulated. In particular, by determining the positions and / or rotational speeds, deviations of these parameters from predetermined desired values can be detected, which are caused by the modulations. In particular, in webs of paper, cardboard or the like, the elastic moduli of such webs can be determined by the measurements of the influencing variables.

In a particularly advantageous embodiment of the invention, both variants of the velocity modulations for determining process variables are combined, that is, applied together.

In a first embodiment, all drives of the web-processing machine are alternately speed-modulated once and speed-modulated once only individual drives or individual groups of drives of the web-processing machines.

In an alternative embodiment, all drives are simultaneously speed modulated with a first modulation frequency and speed modulated individual drives or groups of drives with a second modulation frequency. Since the first and second modulation frequencies differ, the measurement results for the modulations with the first and second modulation frequencies can be separated and evaluated separately.

In both embodiments, the measurement results for the modulations with the first and second modulation frequencies are advantageously related to one another, this preferably taking place by means of a differential measurement. By means of such an evaluation, the speed-dependent friction can be calculated from the measured values for determining local stresses or strains in the material web or for determining the modulus of elasticity of the material web, so that these measured quantities can be determined accurately and without errors.

The inventive method can be used in different web-processing machines. These include in particular printing presses, machines for the production of paper, cardboard, plastic films and composite materials as well as slitter winder as further paper-processing machines. Furthermore, the method according to the invention can be used in machines that process webs that are not made of paper. These include textile machines, in particular machines for the production or processing, in particular finishing of textile webs, in particular knitwear. Furthermore, the web-processing machine may be formed as a film stretching machine. Finally, the web-processing machine can be designed as a straightening device for straightening sheets. Here sheets are unwound from a coil and moved by means of several successively arranged driven straightening rollers back and forth to remove the originating from the winding bend in the sheet.

Figur 1:

Schematische Darstellung einer als Druckmaschine in Einzelständerbauweise ausgebildeten bahnverarbeitenden Maschine.

Figur 2:

Schematische Darstellung einer Schaltungsanordnung mit Antrieben für eine bahnverarbeitende Maschine.

Figur 3:

Schematische Darstellung einer als Druckmaschine in Zentralzylinderbauweise ausgebildeten bahnverarbeitenden Maschine.

Figur 4:

Schematische Darstellung von Komponenten eines Rollenschneiders.

The invention will be explained below with reference to the drawings. Show it:

FIG. 1:

Schematic representation of a designed as a single-stand printing press web processing machine.

FIG. 2:

Schematic representation of a circuit arrangement with drives for a web-processing machine.

FIG. 3:

Schematic representation of a designed as a printing machine in Zentralzylinderbauweise web processing machine.

FIG. 4:

Schematic representation of components of a slitter.

FIG. 1 shows, as the first exemplary embodiment of a web-processing machine, a printing press 1, 1 'in single-stand construction. This printing machine 1, 1 'is used for printing or generally for processing a web formed as a paper web 2. For processing the paper web 2, three processing units 3a, 3b, 3c are provided in the present case, which are arranged one behind the other in the conveying direction F of the paper web 2. Each processing unit 3a, 3b, 3c has as a process element a plurality of driven cylinders, namely an impression cylinder 4, a format cylinder 5 and an anilox roller 6. With the processing units 3 a, 3 b, 3 c, in particular print motifs with different colors can be printed on the paper web 2.

The paper web 2 is withdrawn from an unwinder 7 via a first pulling unit 8 and fed to the processing units 3a, 3b, 3c. After processing the paper web 2 in the processing plants 3 a, 3 b, 3 c, this is fed via a further tensioning unit 8 to a rewinder 9 and wound there. The traction units 8 each consist of two driven counter-rotating transport cylinders 10.

FIG. 2 schematically shows an arrangement of drives 11 by means of which the process elements of a web-processing machine, in particular of the printing press 1 according to FIG. 1, are driven. The drives 11 are designed as three-phase motors, for example synchronous motors, and are each driven by a converter 12. In the web-processing machine according to FIG. 1, preferably the rewinder 9 and the unwinder 7 are operated by asynchronous motors. Of the inverters 12 lead as power-side connections lines 13 to the associated drives 11. In FIG. 2 shows only one such line in each case. Since the converters 12 and drives 11 are each designed in three phases, however, three such lines 13 generally lead from one converter 12 to the associated drive 11. Furthermore, from each converter 12, a signal line 14 leads to the assigned drive 11, via which control commands from the converter 12 the drive 11 can be dispensed. Finally, the inverters 12 are connected via further signal lines 15 to a central controller 16, which controls the operation of the web-processing machine.

In order to determine process variables of the web-processing machines, their drives 11 are speed-modulated.

In the present case, the drives 11 are modulated alternately with two different modulations. In the first modulation, the velocities of all drives of the web-processing machine are modulated at a predetermined modulation frequency. As influencing variables, the torques of the drives 11 are determined by measuring the motor currents in the inverters 12. The measurements of these influencing variables take place in the frequency and phase position of the modulation frequency. This phase-sensitive evaluation eliminates interference such as noise during the measurements. With these measurements, in particular speed-dependent friction is detected in the web-processing machine, while speed-independent friction effects are eliminated by the measurements based on the velocity modulation. The speed-dependent friction effects are based, for example, on the elastic deformations of clichés not shown for printing the paper web 2.

In the second modulation only individual drives 11 are speed-modulated, in the present case, for example, the drives 11 of the central processing unit 3b. As a response to this modulation turn the torques of all drives 11 are determined. In addition, in particular, the positions and / or rotational speeds of the non-modulated Drives 11 are measured to detect deviations in the setpoint values given for this purpose as a result of the modulation. These measurements provide spatially resolved information about the stresses and strains caused by the modulation of the web.

The speed-dependent friction effects are particularly advantageously eliminated by subtraction of the measured values in the first and second modulation, so that the modulus of elasticity of the web can be determined, for example, by evaluating the measurement results for the torques for the machining units 3a, 3b, 3c in the second modulation. An increase in the speed of the drives 11 of the processing unit 3b, for example, increase the web tension between the processing units 3b and 3c and reduce between the processing units 3a, 3b, which is registered with the measurement of the torques. From these measurement results can be concluded from the percentage factor between strain and tension of the paper web 2, so their modulus of elasticity.

In the present case, the first and second modulations are performed alternately. Alternatively, these can also be carried out simultaneously, in which case, however, the modulation frequencies must be different for the first and second modulations in order to be able to separate the respectively obtained measurement results. In principle, only a first or second modulation can be performed.

In general, the amplitudes and frequencies of the modulations are chosen so that they do not affect the processing process of the web. In the present case, this means that the amplitudes of the modulation are chosen so small and the modulation frequency are adapted to the transport of the paper web 2, that they can still be supplied with the required accuracy of the processing units 3a, 3b, 3c.

The method described can be extended or changed so that the tension rollers 10, 10 'are speed-modulated together or against each other. In particular, the coatings of the draw rolls 10, 10 'or their coefficients of friction can thus be controlled.

FIG. 3 shows, as a second exemplary embodiment of a web-processing machine, a printing machine 1, 1 'in central cylinder construction. This printing press 1 also has an unwinder 7, from which a paper web 2 is unwound.

The paper web 2 is fed to a central processing station, which has a central counter-pressure cylinder 4 'and a plurality of inking units 17 distributed in the circumferential direction of the counter-pressure cylinder 4'. Each inking unit 17 comprises a format cylinder 5 'and an anilox roller 6'. The paper web 2 to be printed is guided between the counter-pressure cylinder 4 'and the respective format cylinder 5' running on this lateral surface. The color necessary for the printing process is transferred from an anilox roller 6 'to a printing plate 18 on the respective format cylinder 12'.

The printed paper web 2 is finally fed to a rewinder 9 analogously to the exemplary embodiment according to FIG.

Also in this case, two different speed modulations are performed alternately or simultaneously. In the first modulation, in turn, the velocities of all drives 11 are modulated and, in response to this, the torques of all drives 11 are determined again. In the second modulation, the drives 11 an inking unit 17 are modulated. The measured values for the individual drives 11 are analogous to the exemplary embodiment according to FIG. 1. While information about the speed-dependent frictional forces within the entire web-processing machine results from the measurement results for the first modulation, information is obtained from the measurement results for the second modulations obtained via the elastic deformation of the printing plate 18 of the inking unit 17.

Figure 4 relates to another embodiment of a web-processing machine in the form of a winder, in which a paper web 2 is first cut in the conveying direction F and then wound up. Figure 4 shows a section of a slitter. This section shows two support rollers 19, 20, on which the already rolled up part of the paper web 2 rests as a roller 21. By the rotational movements of the driven support rollers 19,20, the roller 21 is wound further.

The support roller 19 located at the front in the conveying direction F of the paper web 2 runs at a slightly higher surface speed than the carrier roller 20. As a result, a bias is exerted on the paper web 2 to be wound on the roller 21, so that the roller 21 attains a high strength.

In the present case, the speed of the rear support roller 20 is modulated with a modulation frequency, which in turn enables a determination of the modulus of elasticity of the paper web 2. With a known modulus of elasticity wear effects in the surface of the paper web 2 can be detected. In a further modulation, all drives 11 are particularly speed-modulated in order to determine therefrom the speed-dependent friction effects and then to calculate them out in the determination of the modulus of elasticity.

LIST OF REFERENCE NUMBERS

(1)

press

(1')

press

(2)

paper web

(3a)

processing plants

(3b)

processing plants

(3c)

processing plants

(4)

Impression cylinder

(4 ')

Impression cylinder

(5)

format cylinder

(5 ')

format cylinder

(6)

anilox roller

(6 ')

anilox roller

(7)

liquidator

(8th)

tensioning mechanism

(9)

rewinder

(10)

cylinder

(10 ')

cylinder

(11)

drive

(12)

inverter

(13)

management

(14)

signal line

(15)

signal line

(16)

control

(17)

inking

(18)

Printing cliché

(19)

king roll

(20)

king roll

(21)

role

(F)

conveying direction

Claims (20)

Method for operating a web-processing machine having an arrangement of process elements driven by drives (11) for transporting and / or processing a web, characterized in that the speeds of at least part of the drives (11) are modulated with a predetermined modulation frequency, and that for the determination of process variables of the web-processing machine by the modulations conditional changes of influencing variables of the drives (11) are detected. A method according to claim 1, characterized in that as an influencing variable, the torque of at least one drive (11) is measured. Method according to one of claims 1 or 2, characterized in that the position and / or the speed of at least one drive (11) are measured as influencing variables. Method according to one of claims 1 to 3, characterized in that the measurement of an influencing variable in the frequency and phase of the modulation of the speed of the respective drive (11). Method according to one of claims 1 to 4, characterized in that the amplitudes and modulation frequencies of the velocity modulations are chosen so large that the transport and / or machining processes carried out with the process elements remain unimpaired. Method according to one of claims 1 to 5, characterized in that the speed modulations are repeated at predetermined time intervals, and that the results obtained in the individual modulations for the influencing variables are integrated. Method according to one of claims 1 to 6, characterized in that the speeds of all drives (11) of the web-processing machine are modulated. Method according to one of claims 1 to 6, characterized in that the speed of a single drive (11) or the speeds of a group of drives (11) are modulated. Method according to one of claims 1 to 6, characterized in that alternately the speeds of all drives (11) of the web-processing machine and offset in time to the speed of a drive (11) or the speeds of a group of drives (11) are modulated. Method according to one of claims 1 to 6, characterized in that simultaneously the speeds of all drives (11) of the web-processing machine are modulated with a first modulation frequency and the speed of a drive (11) or the speeds of a group of drives (11) with a second modulation frequency are modulated. Method according to one of claims 7 to 10, characterized in that in the modulation of the speeds of drives (11) of the web-processing machine as influencing variables, the torques of all drives (11) are measured. Method according to one of claims 8 to 10, characterized in that in the modulation of the speeds of individual drives (11) as influencing variables, the positions and / or rotational speeds of drives (11) whose velocities are not modulated, are measured. Method according to one of claims 9 to 12, characterized in that in the modulation of the speeds of all drives (11) obtained first measurement results are related to second measurement results obtained in the simultaneous or alternately carried out modulation of the velocities of individual drives (11) become. A method according to claim 13, characterized in that the differences of the first and second measurement results are formed. Method according to one of claims 1 to 14, characterized in that this is used in a as a printing machine (1, 1 ') formed web-processing machine. Method according to one of claims 1 to 14, characterized in that it is used in a web-forming machine designed as a film stretching machine. Method according to one of claims 1 to 14, characterized in that it is used in a machine for the production of paper or cardboard. Method according to one of claims 1 to 14, characterized in that this is used in a slitter. Method according to one of claims 1 to 14, characterized in that it is used in a machine for the production or processing of knitwear. Method according to one of claims 1 to 14, characterized in that this is used in a straightening system for straightening sheets.

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