EP2067725A2 - Method of correcting the axis in a processing machine and processing machine - Google Patents

Abstract

The method involves separating goods web i.e. paper (101) into web tensioning sections, where the tensioning sections are limited by jamming points that include a feeding device (110), printing devices (111-114), and extracting device (115). A pre control of the points limiting the sections and/or the printing devices existing in the sections is implemented under consideration of the automatically determined elasticity module of the material of the goods web and inertia moment of rollers (102) and chill rollers (121-124) existing in the sections during change of rotation speed of points. Independent claims are also included for the following: (1) a processing machine for transporting and processing of goods web (2) a computer program with a program code units to implement the steps of the method for correcting the axis in the processing machine (3) a computer program product with program code units, which are stored on a computer readable data carrier.

Description

The present invention relates to a method for axis correction in a processing machine and a corresponding processing machine, a corresponding computer program and a corresponding computer program product.

Although hereinafter mainly referred to printing presses, the invention is not limited thereto, but rather directed to all types of processing machines in which a web or material web is processed. However, the invention can be used in particular in printing presses such as, for example, newspaper printing presses, commercial printing machines, gravure printing machines, inline flexographic printing machines, packaging printing presses or securities printing machines. The web can be made of paper, cloth, cardboard, plastic, metal, rubber, in foil form, etc.

Background of the Invention In processing machines, in particular printing machines, a web of material is conveyed along driven axes (web transport axes), e.g. Pull rolls or feed rolls and non-driven axes such as e.g. Deflection, guide, drying or cooling rollers moved. The web is simultaneously processed by usually also driven processing axes, for example. Printed, stamped, cut, folded, etc.

The web tension of the web is influenced by so-called. Clamps that clamp the web frictionally, positively or non-positively. These are usually driven transport or processing plants. In a gravure printing machine, a nip is usually formed by a printing unit, in which a frictional unit between the driven pressure cylinder, the impression roller and the material web consists. The web is subdivided into web tension sections, wherein a web tension section is limited by two terminal points. Within a web tension section, further driven and / or non-driven axles may be arranged.

During an acceleration or deceleration phase (rotational speed change), a dynamic force must be used to accelerate or decelerate the non-driven axles. In this case, the moment of inertia and the friction of the non-driven rollers must be applied.

Usually, the machines are set up at low processing speed (set-up speed) to minimize waste. The subsequent acceleration until the production speed is reached results in register and web voltage deviations which must be corrected.

It is known to counteract during the acceleration phase caused by the acceleration strain change by means of angular displacement of printing units, wherein successive printing units are precontrolled by increasing angle offsets.

It is possible to obtain the angle offsets by performing a measuring run. However, there is the disadvantage that waste is generated and evaluations of the register error observed during the measurement run must be carried out. A manual evaluation is error-prone, an automatic evaluation is complicated due to the necessary sensor elements. Furthermore, the implementation of a test drive is relatively time-consuming, since this must be carried out for each occurring different acceleration phases.

It is also possible to computationally determine the precontrol values since these are proportional to the mass inertia of the non-driven axes, to the reciprocal of the modulus of elasticity and to the acceleration. It is known to manually set the mass inertia and the modulus of elasticity by the user.

A disadvantage of this solution according to the prior art is that in the specification of the data by the user on the one hand input errors can happen and on the other hand necessary data such as in particular the modulus of elasticity are not always known exactly.

It is therefore the object to provide an improved axis correction during an acceleration or deceleration phase.

This object is achieved by a method for axis correction according to claim 1, a processing machine according to claim 8, a computer program according to claim 14 and a computer program product according to claim 15. Advantageous developments are subject of the dependent claims and the following description.

Advantages of the invention

In a method according to the invention for axis correction, which in particular results in web tension and / or register control or adjustment, during a rotation speed change of a clamping point delimiting a web tension section, precontrol of this clamping point delimiting the web tension section and / or a machining axis present in this web tension section takes place taking into account the modulus of elasticity the material of the web and an inertial moment of at least one non-driven axis present in this web tension section, wherein the modulus of elasticity of the material of the web is automatically determined becomes. One way to determine the modulus of elasticity of the material of a web is, for example, in the DE 10 2005 056 802 A1 disclosed.

Due to the inventive axis correction, in particular web tension control and / or register control, taking into account the modulus of elasticity of the material of the web and an inertial moment of at least one non-driven axis present in a web tension section with automatic determination of the modulus of elasticity of the material of the web, the disadvantages of the prior art can be reduced ,

Advantageously, no production-dependent material data must be entered or made known by retrieving earlier productions, since the data can be determined independently or automatically. It is possible to carry out the determination of the settings of the acceleration compensation when the machine is at a standstill, whereby no waste is generated.

The pilot control according to the invention represents a significant improvement over the prior art, since now a predictive feedforward control of the expected error can be provided instead of having to react to an error that has already occurred. Due to the axis correction in the sense of a web tension adjustment or regulation, web tension changes of an acceleration or deceleration phase are reduced, which directly translates into a reduction of the reject. Due to the lower web tension changes register deviations are also reduced, which by the also described Axis correction in terms of register control or control can be further reduced. Due to the additional pre-control, more effective control strategies can be designed, since greater influence on the material web is possible. If, for example, the printing press has reached the steady state, longitudinal register deviations can be compensated more quickly by means of stationary control strategies, in which the feedforward control is included. If the machine is in a dynamic transitional phase, such as changes in the train tension setpoint or web speed in the machine, the feedforward control provides faster dynamic register control.

The inventive measure a greater decoupling of the web is achieved in register and / or web tension controls and lowered the influence of the inertia and friction moments of the non-driven axles. The stationary and dynamic error between the individual processing or printing units decreases. In addition, a faster compensation of register errors can take place. The retroactive effect of an acceleration or deceleration phase on the web tension is reduced, which makes possible in particular faster or more dynamic acceleration or deceleration processes. Overall, waste or waste is significantly reduced, which among other things leads to a reduction in production costs.

Advantageously, the pilot control of all affected axes of the web tension section takes place. In particular, for controlling or adjusting the web tension in a web tension section, a feedforward of the web tension section limiting clamping points and for controlling or setting the register of a processing axis within a web tension section a pre-control of the machining axis and / or the web tension limiting terminal points performed.

Typically, in the case of web transport axes or machining axes, additive velocities, multiplicative velocity factors (so-called fine adjustment, gear ratios) and / or additive angle offsets are precontrolled.

Advantageously, the moment of inertia to be considered also include the friction moments of the axes. The effective moments of inertia of the non-driven axles can be determined in particular by a measuring run.
It can be calculated back from an evaluation of the register error of the products on the effective moments of inertia of the non-driven axles. Likewise, an online evaluation of the measured register errors can be carried out. In addition to the determination by test drive is also a determination by an online observation of the register errors occurred as well as an estimate based on the moments of inertia, for example by means of model following, observers, Kalman filtering, etc. possible. Finally, the moment of inertia can also be calculated knowing the mechanical parameters such as diameter, material, material distribution, etc. of the non-driven axes. Since the mechanical structure of a processing machine usually does not or only rarely changes, the determination of the moments of inertia is only once or rarely necessary. The specific values will be then saved and can be used for all subsequent productions.

Advantageously, the precontrol takes place taking into account the respective (effective) moment of inertia of all non-driven axes present in a web tension section. Thus, the quality of the feedforward control can be further increased.

Preferably, the respective moments of inertia of all non-driven axles present in this web tension section are concentrated to a total moment of inertia to be considered for this web tension section. It is an easy-to-perform, yet good-results measure. By a fictional "emphasis" is only a total moment of inertia to consider. This total moment of inertia can be determined, for example, in one of the above-mentioned ways (test drive, etc.).

It is particularly expedient if precontrol values for the precontrol of the clamping point and / or the machining axis for decoupling at clamping points and / or machining axes of adjacent web tension sections are statically and / or dynamically cascaded. The cascading can take place with different factors, for example inverse, proportional, proportionate or dynamic, etc., in order to decouple adjacent web tension sections from the precontrol in the relevant web tension section.

Likewise advantageously, the precontrol is additionally taking into account the rotation speed change the nip. Since the expected error is proportional to the occurring rotational speed change, ie positive or negative acceleration of the axis, this acceleration is advantageously also taken into account in the pilot control. The acceleration can be determined, for example, by deriving certain transmitter values, for example two times the derivative of the position encoder values or a one-time derivative of the speed sensor values. For the position or speed measurement, for example, a scan of printed on the web information such as brands, perforation, etc. take place. Also, the determination by means of an accelerator is possible. Also suitable are the transmission of the values from the machine control to the processing unit for the web tension control or register control, for example by means of fieldbus communication, where, for example, a setpoint position, setpoint speed, setpoint acceleration, setpoint jerk, actual position, actual position Speed, actual acceleration or actual jerk of the machine master position can be transmitted. Also possible is a transmission of binary signals which indicate a change in speed, from the machine control to the arithmetic unit for the web tension or register control and the knowledge of fixed jerk or acceleration values in the arithmetic unit for the web tension or register control. Finally, an estimate of the acceleration based on other process variables such as the drive torque can be done.

The arithmetic unit of the processing machine according to the invention is set up in an advantageous development to carry out the steps described above.

Appropriately, in a processing machine according to the invention, the arithmetic unit and the motion control (motion control) of the drive's own axes and / or the machine sequence control are integrated in a common control hardware. Such processing machines are available in a compact form and offer a simplified handling, since no combination with external components is required.

The invention additionally relates to a computer program with program code means in order to carry out all the steps of a method according to the invention when the computer program is executed on a computer or a corresponding arithmetic unit, in particular in a processing machine according to the invention.

The inventively provided computer program product with program code means which are stored on a computer-readable data carrier is designed to perform all the steps of a method when the computer program is executed on a computer or a corresponding computing unit, in particular in a processing machine. Suitable data carriers are, in particular, floppy disks, hard disks, flash memories, EEPROMs, CD-ROMs, DVDs and the like. It is also possible to download a program via computer networks (Internet, intranet, etc.).

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained not only in the each combination specified, but also in other combinations or alone, without departing from the scope of the present invention.

The invention is illustrated schematically with reference to an embodiment in the drawing and will be described below in detail with reference to the drawings.

figure description

FIG. 1

shows a schematic representation of a preferred embodiment of a machine according to the invention designed as a printing machine;

FIG. 2

schematically shows a dependence of a web tension on time in a dynamic case in the prior art;

FIG. 3

schematically shows a dependence of a register deviation of time in a dynamic case in the prior art; and

FIG. 4

schematically shows a dependence of a register deviation of time in a preferred embodiment of the invention.

In FIG. 1 is a preferred embodiment of a designed as a printing press, processing machine according to the invention generally designated 100. A printing material, for example paper 101, is fed to the machine via a feed unit 110. The paper 101 is through as printing units 111, 112, 113, 114 formed clamping points and printed and output by a pull-out unit 115 again. The input, extraction and printing units 110 to 115 are positionable, in particular cylinder or angle correctable arranged. The printing units 111 to 114 are located in a web-tension-controlled area between the intake unit 110 and the extension unit 115.

The printing units 111 to 114 each have a printing cylinder 111 'to 114', against which a respective impression roller 111 '' to 114 '' is made with strong pressure. The impression cylinders 111 'to 114' are individually and independently drivable. The associated drives 111 '' 'to 114' '' are shown schematically. The impression rollers 111 '' to 114 '' are freely rotatable. The intake and exhaust units 110 and 115 respectively have two counter-rotating cylinders that guide the paper 101. Also, the intake and the extension unit 110 and 115 are individually by a drive 110 '' 'and 115' '' driven. The feed and withdrawal unit 110, 115 and the printing units 111 to 114 together with the continuous paper 101 form a frictionally connected unit. The infeed 110, the extension unit 115 and the printing units 111 to 114 each represent a nip.

In the web sections between the individual printing units 111 to 114, the paper 101 is guided over unspecified explained roles, which are designated 102. For reasons of clarity, not all rollers are provided with reference numeral 102. It may in particular be pulleys, drying, trimming equipment, etc.

The web 101 is guided after a printing step in one of the printing units 111 to 114 via cooling rollers. For this purpose, in the web section between the first printing unit 111 and the second printing unit 112, a cooling roller 121, in the section between the second printing unit 112 and the third printing unit 113, a cooling roller 122, in the section between the third printing unit 113 and the fourth printing unit 114, a cooling roller 123 and in the section between the fourth printing unit 114 and the extension unit 115, a fourth cooling roller 124 is arranged.

The cooling rollers 121 to 124 and the rollers 102 each have an effective moment of inertia, which adversely affects an acceleration phase of the printing press. According to the illustrated preferred embodiment of a printing machine, all clamping points during an acceleration phase, taking into account the modulus of elasticity of the material of the web and the effective moments of inertia of the cooling rollers 121 to 124 and the rollers 102 are piloted. The effective moments of inertia are determined beforehand, usually once, by means of a measuring run and a subsequent evaluation. The modulus of elasticity is determined automatically. In an acceleration phase, a precontrol taking into account the modulus of elasticity, the effective moments of inertia and the acceleration is carried out. In this case, the precontrol can be carried out with dynamic timers, for example with the aid of a DT1 element (differentially delaying element), wherein T1 is chosen to be proportional to the track length / machine speed. The feedforward control can comprise additive angle values. As a result, one obtains an approximately constant course of the web tension in a desired section of the web and from this a nearly vanishing register deviation, as shown by FIG. 4 is shown.

The following is based on FIG. 1 described a way to determine the modulus of elasticity. First, for example, the feed train 110 is detected and the subsequent printing unit 111 is moved by a predeterminable angle Δφ. It is preferably possible to make a setting by means of an angular movement in the position control. The angular movement can be carried out incrementally in small increments in order to prevent excessive stretching of the material into the plastic area. Likewise, an adjustment can be carried out by means of an angular movement in the speed control. Also, adjustment can be made by means of an angular movement in the torque control. In addition, it is preferably possible to perform a setting by means of an angular movement in the position or speed control with simultaneous limitation of the drive torque. The advantage of this is that in contrast to a torque control, the angular movement speed can be limited - and thus can be moved relatively gently in the torque limit.

The elastic modulus E can be calculated as E = (ΔF · l ₀ ) / (A · Al) with ΔF: applied force; · l ₀ : original length; A: surface of the material web; Δl: achieved change in length. The force .DELTA.F can be determined by means of a load cell (not shown) arranged in the web section between infeed unit 110 and first printing unit 111. The length l ₀ and the area A of the web between the feed train 110th and the first printing unit 111 are known or can be measured in a simple manner. Finally, the change in length .DELTA.l can be determined as the product of angular displacement .DELTA..phi. And radius of the pressure roller or by means of a position sensor (for example, the motor encoder). Alternatively, a voltage change can also be brought about by predetermining a web tension by means of the force of a dancer roller in the feeder and / or extension unit. If a dancer is present in the feeder or extension unit, a force can be impressed into the material web with the specification of the dancer pressure. This impressed force then gives a web tension. Also, the specification of a web tension can be done by means of a specification of a force of a not completely employed impression. When the impression roller is turned on, the webbing can also be used to impress a web tension. Finally, the obtained data can be used to determine a production-dependent constant k = EA.

Alternatively, for example, instead of the measurement by means of a (existing) load cell, the applied engine torque can be used as a force variable. In this case, on the one hand friction effects, on the other hand tensile forces outside the web tension path to be considered, since these each affect the applied engine torque. The latter can then be neglected if the material web outside of the two clamps clamping the web of material, in the selected example infeed unit 110 and first printing unit 111, is almost completely relaxed during the measurement. Otherwise, a web tension before or after the measuring section falsifies the web tension determined from the measured engine torque.

In the following, a possibility for determining the inertial masses will also be disclosed by way of example. If the inertial masses are not known or are permanently stored in the acceleration compensation as constants, these can be determined with a known modulus of elasticity of the web by means of a measuring run, with two variants being proposed. On the one hand, the resulting web tension change, for example by means of a load cell, can be determined during an acceleration phase. On the basis of this measurement, the effective inertia mass is then calculated with the aid of the known E modulus on the basis of the web tension change and the machine acceleration. On the other hand, during an acceleration phase, the resulting register error can be determined. With a known modulus of elasticity, the resulting web tension change can be determined based on the registration error. Together with the machine acceleration, in turn, the effective inertial mass can be determined.

In FIG. 2 the course of a web tension in a dynamic case in the prior art is plotted against time in a diagram 10, in which two web tension curves 13 and 14 are shown. The web tension is plotted in the diagram 10 on a y-axis 12 against the time t on an x-axis 11. FIG. 2 shows the web tension curve in a dynamic case in which an acceleration of the rollers involved takes place.

In the diagram 10, two web tension curves 13 and 14 are shown, which are to be assigned to different web tension subsections. Considered is a web tension section, which is driven by a non-driven Axis, in the example shown a chill roll, is divided into two adjacent web tension subsections. At the ends of the web tension section is in each case a nip (driven axis), in the example shown a driven pressure roller. With reference to FIG. 1 For example, such a web tension section can be identified between the printing couple 112 and the printing couple 113, which is subdivided by the cooling roll 122 into two web tension subsections. It should be noted at this point that the figure according to FIG. 1 shows a printing machine according to the invention, in which both the modulus of elasticity of the material of the web and the effective moment of inertia of the cooling roller 122 is taken into account for a pilot control, whereas the FIG. 2 refers to a printing press, in which such a pilot control is not provided.

Following the course of the web, there is the web tension subsection to which the web tension profile 14 is assigned, between a nip and a non-driven axis, and the web tension subsection to which the web tension profile 13 is attributed, then directly in the web path between said non-driven axis and a following nip.

As can be seen from the diagrams 10, the web tension in the region between a nip and a subsequent non-driven axis regularly has a lower value than in the area between said non-driven axis and a subsequent nip.

In an acceleration phase 15 according to FIG. 2 For example, a dynamic force 16 corresponding to the difference of the web tension courses 13 and 14 is used to drive the non-driven roller. In the example shown, the web is accelerated within 30 s from 30 m / min to 200 m / min. In this case, the moment of inertia and the friction, ie the effective moment of inertia, the non-driven axles must be applied. During the acceleration phase, the web tension drops behind a nip and rises before the subsequent nip, as the non-driven rollers are accelerated.

After the acceleration, a stationary state sets in which FIG. 2 on the right side of the diagram from about t = 150 s is recognizable. In the steady state, a friction torque of the non-driven axle must be applied. This leads to a higher web tension behind a non-driven axle and the subsequent nip in the web path, since the nip has to exert a force to drive the non-driven axle. This force corresponds to a difference 17 between the illustrated web tension 13 and 14.

In FIG. 3 By way of example, a resulting register error is shown on a processing plant. In a diagram 20, the course of a register deviation versus time is plotted, wherein two graphs 23 and 24 are shown, which are to be assigned to different moduli of elasticity. The register deviation is plotted in the diagram 20 on a y-axis 22 against the time t on an x-axis 21. It is an acceleration phase from 30 m / min to 250 m / min in 90 Seconds with materials with different modulus of elasticity. The acceleration as well as the effective moment of inertia to be considered are identical for both curves. The material of the web, which is associated with the curve 23, has an E-modulus of about 8.6 × 10 ⁹ N / m ² . The material of the web, which is associated with the curve 24, has an E-modulus of about 3.6 · 10 ⁹ N / m ² . It is the different influence of the dynamic register error at the same moment of inertia of the non-driven rollers and the same acceleration clearly.

In FIG. 4 Finally, the curve 33 of a register error resulting from the use of the invention is shown on a processing unit. The register deviation is plotted on a y-axis 32 against the time t on a x-axis 31 in a diagram 30. It is an acceleration phase over 30 seconds shown. It becomes clear that the register deviation almost disappears.

It is understood that in the illustrated figures, only a particularly preferred embodiment of the invention is shown. In addition, any other embodiment is conceivable without departing from the scope of this invention.

100

Druckmaschine

101

Papier

102

Rolle

110

Einzugswerk

110'''

Antrieb

111, 112, 113, 114

Druckwerk

111', 112', 113', 114'

Druckzylinder

111'', 112'', 113'', 114''

Presseur

111''', 112''', 113''', 114'''

Antrieb

115

Auszugswerk

115'''

Antrieb

121, 122, 123, 124

Kühlwalze

10, 20, 30

Diagramm

11, 21, 31

x-Achse

12, 22, 32

y-Achse

13, 14

Bahnspannungskurve

15, 25

Beschleunigungsphase

16, 17, 26

- Kraft

23, 24, 33

Registerabweichungskurve

LIST OF REFERENCE NUMBERS

100

press

101

paper

102

role

110

infeed

110 '''

drive

111, 112, 113, 114

printing unit

111 ', 112', 113 ', 114'

pressure cylinder

111 '', 112 '', 113 '', 114 ''

impression roller

111 ''',112''', 113 ''',114'''

drive

115

excerpt

115 '''

drive

121, 122, 123, 124

chill roll

10, 20, 30

diagram

11, 21, 31

X axis

12, 22, 32

y-axis

13, 14

Web tension curve

15, 25

acceleration phase

16, 17, 26

- Force

23, 24, 33

Register deviation curve

Claims (15)

Method for correcting the axis in a processing machine (100) which has at least two driven transport axes (110, 115), at least one non-driven or driven machining axis (111, 112, 113, 114) and at least one for transporting and processing a material web (101) further non-driven axle (102, 121, 122, 123, 124),
wherein the web (101) is subdivided into at least one web tension section, wherein a web tension section is bounded by two clamping points (110-115) designed as driven transport or machining axes,
wherein during a rotation speed change of a web tension limiting clamping point (110-115) precontrol of this web tension limiting clamping point (110-115) and / or existing in this web tensioning machining axis (111-114) taking into account the modulus of elasticity of the material of the web and an inertial moment of at least one non-driven axis (102, 121-124) present in this web tension section takes place, the modulus of elasticity of the material of the web (101) being determined automatically. The method of claim 1, wherein the precontrol is additionally taking into account the rotation speed change. The method of claim 1 or 2, wherein the feedforward takes into account the respective moment of inertia of all present in this web tension section non-driven axles (102, 121-124). The method of claim 3, wherein the respective moments of inertia of all non-driven axles (102, 121-124) present in this web tension section are concentrated to a total moment of inertia to be taken into account for this web tension section. Method according to one of the preceding claims, wherein pre-control values for the precontrol of the clamping point (110-115) and / or the machining axis (111-114) for decoupling at clamping points (110-115) and / or processing axes (111-114) of adjacent web tension sections statically and / or dynamically cascaded. Method according to one of the preceding claims, wherein the modulus of elasticity of the material of the material web (101) is determined automatically on the basis of a strain change and a web tension change. Method according to one of the preceding claims, wherein the moment of inertia of the at least one non-driven axle (102, 121-124) to be considered is determined by means of a measuring run. Processing machine (100) for the transport and processing of a web (101) at least two driven transport axes (110-115), at least one non-driven or driven machining axis (111-114) and at least one further non-driven axle (102, 121-124), wherein the web (101) is subdivided into at least one web tension section, wherein a web tension section is bounded by two clamping points (110-115) designed as driven transport or machining axes,
wherein the processing machine (100) has a computation unit (200) which is set up to determine the modulus of elasticity of the material of the material web and during a rotational speed change of a clamping point delimiting a web tension section (110-115) a precontrol of this clamping point bounding the web tension section (110- 115) and / or a machining axis (111-114) present in this web tension section by means of precontrol values taking into account the determined modulus of elasticity of the material of the web (101) and an inertial moment of at least one non-driven axle (102, 121-124) present in said web tension section , Processing machine (100) according to claim 8, wherein the arithmetic unit (200) is adapted to determine the pilot control values taking into account the rotational speed change. Processing machine (100) according to claim 8 or 9,
wherein the arithmetic unit (200) is adapted to determine the precontrol values taking into account the respective moment of inertia of all non-driven axles (102, 121-124) present in this web tension section, in particular the respective moments of inertia of all concentrate in this web tension section existing non-driven axles (102, 121-124) to be taken into account for this web tension section total moment of inertia. Processing machine (100) according to one of claims 8 to 10, wherein the arithmetic unit (200) and the motion control of the driven axles (110-115) and / or the machine sequencer are integrated in a common control hardware. Processing machine (100) according to one of claims 8 to 11, wherein the arithmetic unit (200) is adapted to determine a strain change and a web tension change and to determine the modulus of elasticity of the material of the web based on this particular strain change and web tension change. Processing machine (100) according to one of claims 8 to 12, wherein the arithmetic unit (200) is adapted to determine the moment of inertia of the non-driven axle (102, 121-124) to be considered by means of a measuring run. Computer program with program code means for carrying out all the steps of a method according to one of Claims 1 to 7, when the computer program is executed on a computer or a corresponding computing unit (200), in particular in a processing machine (100) according to one of Claims 8 to 13. A computer program product comprising program code means stored on a computer readable medium for performing all the steps of a method as claimed in any one of claims 1 to 7 when the computer program is run on a computer or corresponding computing unit (200), in particular a processing engine (100) of any one of Claims 8 to 13, is executed.

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