EP2064060B1 - Method for determining a repeat length/web tension function on a printing press, and regulating auxiliary apparatus for carrying it out - Google Patents

Abstract

The invention describes a method for operating a printing press (100), in which method a repeat length/web tension function is determined and which method comprises at least the following steps: a) continuous printing of a printing motif (2) by way of at least one format cylinder (12) onto the printing-material web (1, 1'); b) loading of the printing-material web (1, 1') with a first web tension F1; c) measuring of the web tension Fi, measuring of the actual repeat length Li and storing of the repeat length/web tension pair of values (Li; Fi) d) changing of the web tension Fi of the printing-material web (1, 1') and at least single repetition of step c); e) calculation of the repeat length/web tension function from the repeat length/web tension pairs of values (Li, Fi).

Description

The invention relates to a method for determining a repeat length web tension function on a printing machine and to a control auxiliary device for carrying out the method.

In web-fed rotary printing presses, a motif is printed by means of printing plates in a similar and sequential manner on a moving substrate web. The printing form is part of a printing cylinder, which rotates continuously.

The repeat length is the length of the printed web during one revolution of the printing cylinder; the circumference of the cylinder primarily determines the repeat length. Secondary process parameters additionally influence the repeat length. These are essentially the elongation of the web in the print and in web tension-free state and state changes of the web after printing, z. B. by drying influences. In general, the repeat length is of interest as an unstretched web section and is therefore used in practice as a characteristic.

When printing, a substrate always has an elongation caused by a web tension. A web tension is always necessary for the transport of a running substrate web, since a web can only be guided so stable that no loose occurs, guide rollers are driven in the web and a constant lateral position of the web is achieved. Under the influence of a tensile force of the substrate thus undergoes an elongation, of its cross-section and of its elastic properties depends. The elastic properties of the web can be described by the modulus of elasticity, the so-called modulus of elasticity. HOOK's law is suitable for describing the relationships. A web tension is locally impressed by known web guiding devices such as advantages and pendulum rollers and assumes a different size in the course of the track depending on (Leitwalzen-) friction, pressure rollers and other drives. If a stretched web is printed and then a stretch-free state is set outside the web transport, then the web relaxes, so that the considered web section becomes shorter. A determination of the repeat length in the unstretched, web tension-free state is not possible within the printing press during the rail transport.

It is known that in series printing machines, in particular offset printing, strains on speed ratios of the web in the infeed and outfeed of a printing machine are determined and thus repeat lengths are determined and set. Especially with flexible substrates of packaging printing, z. B. LDPE, PP or PET, however, this method reaches its limits, because the ratio of strains in different web guide sections is indeed determinable, but not an absolute elongation compared to the relaxed state. Since the modulus of elasticity varies from substrate to substrate depending on the type and batch, and is also highly temperature-dependent, large local inaccuracies arise. Calculations on inaccurately determinable elastic properties and web tensions, in turn, are subject to high tolerances and so far provide only insufficient accuracy.

In packaging printing, it is therefore traditionally customary to determine the repeat length outside the printing press. A sufficiently long section of track is cut out of the track and spread on a measuring table free of tension. With the aid of measuring rulers, the repeat length is then determined by measuring the length between identical motif elements of consecutive rapports.

The applicant is also aware of attempts to determine the repeat length inline by means of a video web observation. The pure measured value of the length can be calculated by means of measured web tension, estimated modulus of elasticity and web cross-section as indicated above. In addition to the unknown modulus of elasticity, the deviating temperature of the printing material, with its effects on the modulus of elasticity and on its thermal expansion, in particular leads to such a method yielding inadequate results and being unable to prevail.

Thanks to the identified shortcomings of these prior art methods, it is not possible, for example, to determine which change the repeat length experiences when operating parameters of the printing machine-such as the printing speed or the setting of the printing rollers to the impression cylinders-are changed during the current printing operation. The WO 92/10419 A suggests therefore to change the web tension in the printing operation and to measure the repeat length change as a function of the web tension. On the basis of the value pairs thus obtained, a repeat length web tension function is calculated.

However, it has been shown that the use of the functions gained in this way can not completely rule out quality defects as a result of variations in repeat length.

The object of the invention is therefore to propose a method that further reduces these quality deficiencies.

The object is achieved by the method features of claim 1.

According to the invention, therefore, the repeat length (actually the repeat actual length in the printing operation) is determined several times under variable web tension by a measuring system and determined value pairs between the measured repeat length and the applied web tension. In this case, the method according to the invention is based on the idea that the measured repeat length shows a functional relationship to the web tension and virtually maps the HOOK's law, as long as the web tension remains sufficiently small, that is approximately has a linear course in which the modulus of elasticity determines the slope of the straight line. Regardless of the absolute values for repeat length and web tension given at the measuring location, the length of the repeat, as would be the case on an unstretched printing substrate, can be determined as a so-called normalized repeat length.

The method also makes use of the fact that changes in the printing parameters in printing operation (eg speed and positioning), which influence the repeat length, generally also affect the web tension

• iterative Einprägung von äußeren Kräften, z. B. über angetriebene Leitwalzen, um schnell hintereinander Werte-Paare mit größeren Abständen zueinander zu erhalten und damit die Genauigkeit des Regressionsverfahrens zu erhöhen, wobei die Kräfte schrittweise oder auch kontinuierlich von Messung zu Messung verändert werden können;
• simultane Einprägung von unterschiedlichen äußeren Kräften in verschiedenen Bahnabschnitten und
• Nutzung von im Druckprozess vorhandenen Schwankungen der Bahnspannung durch zufällige Auswahl von Mess-Zeitpunkten im laufenden Druckvorgang.

The different web tensions required for the measurement processes can be obtained by:

• iterative impression of external forces, eg. For example, via driven guide rollers, in order to obtain pairs of values with greater distances one behind the other in quick succession and thus to increase the accuracy of the regression method, wherein the forces can be changed step by step or even continuously from measurement to measurement;
• simultaneous impression of different external forces in different track sections and
• Use of variations in web tension in the printing process by random selection of measuring times in the current printing process.

The term function is to be understood first in the full breadth of its mathematical meaning. As a rule, you will need at least two pairs of values from web tension and repeat length actual values. An extrapolation between these value pairs is a simple function. The extrapolation can be done in the form of a straight (linear relationship) or with another shape. In the formation of the function, other analytical contexts or empirical values can be included.

In a preferred embodiment of the invention, the repeat length can already be determined, which results when the printing material is relaxed. This size is referred to below as standardized repeat length, wherein the normalized repeat length, which results from the actual values measured on the tensioned substrate during ongoing printing operation, is called the normalized actual repeat length.

In general, however, the machine operator - or, in the case of the most modern printing presses, a machine control device - will have to observe a setpoint for the repeat length of the tension-free printing material in the future. This setpoint will be referred to below as the standardized nominal repeat length, especially in relation to a closed-loop control method.

Particularly advantageous is the low temperature sensitivity of the method according to the invention. While in the unstretched state at a temperature change only comparatively small changes in length of the printing material are effected, the temperature influence increases with increasing elongation strongly, since the modulus of the printing material, especially in polymeric films, has a strong temperature dependence.

By individual measurements, the temperature-related proportion of Rapportlängenänderung is not determinable. By contrast, the influence of the temperature-induced strain or the temperature-dependent elastic modulus can be determined and taken into account by the extrapolation according to the invention. In view of the very thin cross-sectional area of a printing material web, the terms "force" and "(web) tension" are often set the same in the printing technology, as in the description of the present invention, although according to the physical definition of the stress takes into account a surface reference of the forces acting would have to be.

On the basis of a comparison of the normalized repeat length with the nominal report length, manual adjustments can be made. However, the value can also be continuously determined in the context of a control method according to claim 9 and used to calculate a manipulated variable.

A mixed form between a fully automatic control method and a semi-automatic method is also possible, in that the operator makes settings interactively in a control process based on the standardized repeat length, for example initiating measures for changing the web tension. In any case, the printer or a control device of the printing press with the normalized repeat length is provided with a reliable characteristic value. The printer is thus relieved of manual checking and adjustment work, the available capacity of the printing press is increased and waste and complaints are avoided. Cost and quality advantages increase the value of the printing press, especially in packaging printing with its flexible substrates.

A regression line through the value pairs is suitable for extrapolating the course linearly to the web tension zero. In addition to the repeat length for the unstretched substrate as a parameter is with knowledge of the slope of the Straight line and the repeat length can be calculated for any web tension and can be passed to such further processing stations of the printing material such as a cutting device in which other web tension as in the printing machine itself are necessary.

1. i) Bilden von Wertepaaren von Rapportlänge (Istlänge) und Bahnspannung im Druckbetrieb
2. ii) Aufstellen einer Rapportlängen-Bahnspannungsfunktion
3. iii) Berechnung des normierten Istwertes der Rapportlänge
4. iv) Bilden der Differenz zwischen normiertem Istwert zu normiertem Sollwert.
5. v) Berechnung von Korrekturwerten, mit denen Mittel zum Ändern der Rapportlänge eingestellt werden.

When controlling the repeat length, for example, you can proceed as follows:

1. i) forming pairs of values of repeat length (actual length) and web tension in printing operation
2. ii) Establishing a repeat length web tension function
3. iii) Calculation of the normalized actual value of the repeat length
4. iv) forming the difference between normalized actual value to standardized nominal value.
5. v) Calculation of correction values which are used to set means for changing the repeat length.

• So können beispielsweise auch aus einem Vergleich der nach den Schritten i) und ii) ermittelten Rapportlängen-Bahnspannungsfunktion der Istwerte und
• einer beispielsweise in einem vorhergehenden Druckvorgang ermittelten Sollfunktion Korrekturwerte ermittelt werden.

However, there are alternative options in the design of the regulatory procedure:

• Thus, for example, from a comparison of the determined according to steps i) and ii) repeat length web tension function of the actual values and
• a determined, for example, in a previous printing process setpoint correction values are determined.

The methods seem to have in common that Rapportlängenist- and set values, and a Rapportlängen web tension function are needed.

In a normal control process, there is an adjustment or correction of the controlled variable within a desired range or within a tolerance range around a target value. Here, the tolerance range may be specified in a machine control, or it may be due to the imperfection of the setting or measuring process or more Adjust fluctuations of the production parameters. This circumstance should be taken into account by the relevant design of the language of the claim, in which the regulatory procedure is claimed.

By means of means for adjusting the web tension are to be understood by control signals activatable active components such as motors or actuators, which have an influence on the web tension.

Thus, a change in the web tension for purposes of control, inter alia, be made by the relative (or differential) speed of the format cylinder is changed with respect to one or the impression cylinder.

Alternatively or additionally, a change in the web tension before entry to the format cylinder (here the controllable components would be the drives of the cylinder or the winding or unwinding or transport cylinders such as a chill roll extract) made.

A stronger employment or a differential speed of the pressure roller 13 can change the web tension in this context. Also pendulum rollers are eligible for this. For example, in the case of the pendulum rollers, a change in position of the roller axis relative to the track or a change in the course of the track with a suitable actuating element is also possible).

The aforementioned measures are in principle also suitable for varying the web tension for measurement purposes.

• Mittel zum Beaufschlagen einer Bedruckstoffbahn mit veränderbaren Bahnspannungen Fi,
• Mittel zum Messen einer Rapportlänge li eines Druckmotivs auf der Bedruckstoffbahn;
• Mittel zum Messen der Bahnspannung Fi;
• einer Auswertungseinheit zur Berechnung der Rapportlängen-Bahnspannungs-Funktion und/oder eines Elastizitätsmoduls
• Mittel zum mehrfachem Durchführen des Verfahrens bei unterschiedlichen Temperaturen der Bedruckstoffbahn (1; 1'), welche zum Speichern jeweils eines Datensatzes aus den Rapportlängen-Bahnspannungs-Wertepaaren (L_i; F_i) und der gemessenen Bedruckstofftemperatur (T_i) eingerichtet sind,
• und Mitteln zur Berechnung eines temperaturabhängigen E-Moduls E(T) aus diesen Datensätzen.

The invention also provides a control auxiliary device for determining a repeat length web tension function on a printing press, with which the methods according to the invention can be carried out and which comprises at least the following subassemblies:

• Means for applying a printing material web with variable web tension Fi,
• Means for measuring a repeat length li of a print motif on the substrate web;
• Means for measuring web tension Fi;
• an evaluation unit for calculating the repeat length web tension function and / or a modulus of elasticity
• Means for multiple execution of the method at different temperatures of the printing material web (1; 1 '), which are configured to store a respective record of the repeat length-web tension value pairs (L _i ; F _i ) and the measured printing material temperature (T _i )
• and means for calculating a temperature-dependent modulus of elasticity E (T) from these data sets.

As a rule, the repeat length-web tension value pairs will be stored in a memory unit before they are fed to the evaluation unit. Often they will remain in the memory afterwards. However, an absolute necessity of such a storage unit may not initially exist, since an immediate direct calculation of the function without a buffering of values appears possible.

Further advantageous embodiments of the method and the control auxiliary device according to the invention can be found in the dependent claims and are explained in more detail below with reference to the drawings. The

• Fig.1 eine Zentralzylinderdruckmaschine in schematischer Seitenansicht,
• Fig. 2 einen Ausschnitt einer Bedruckstoffbahn in Draufsicht,
• Fig. 3 die Rapportlänge, aufgetragen über die Bahnspannung,
• Fig. 4 die Rapportlänge, aufgetragen über die Bahnspannung bei verschiedenen Temperaturen,
• Fig. 5 eine Messanordnung im Regelkreis und
• Fig. 6a, 6b Bahnspannungsabschnitte mit gestuften Bahnspannungen.

Figures show in detail:

• Fig.1 a central cylinder printing machine in a schematic side view,
• Fig. 2 a section of a printing substrate in plan view,
• Fig. 3 the repeat length, plotted against the web tension,
• Fig. 4 the repeat length, plotted against web tension at different temperatures,
• Fig. 5 a measuring arrangement in the control loop and
• Fig. 6a, 6b Web tension sections with stepped web tension.

Fig. 1 shows a printing machine 100, which is formed in the embodiment as a central cylinder flexographic printing machine. At one Counter-pressure cylinder 11 with a large diameter, a plurality of format cylinders 12 can be adjusted, which carry the image-generating artwork.

The printing material is fed in the form of a printing material web 1 from a development roller 20 and initially passes over a pendulum roller 21 in order to compensate for any uneven web tension development which may be caused by the unwinding device 20.

The printing substrate 1 then passes over a preference 22, where a first web tension measuring roll 14 is arranged, over which the preference regulates the web tension. About a pressure roller 13, the web is guided on the impression cylinder 11. From there, the printing material web 1 passes through a drying device 30 via a cooling roller extension 32, on which a further web tension measuring roller 31 is provided. In spatial proximity to a first measuring device for the actual Rapport-length, here shown in the form of a camera 51, arranged.

The continuous line indicates the course of the printing material web 1 in the so-called straight printing, in which the print motif is applied laterally correct on a transparent or non-transparent substrate.

The dot-dash line indicates the leadership of the printing material 1 'at the so-called counter pressure. The same camera 51, which is used in straight printing, can capture the printing motif applied on the reverse in the case of a transparent printing substrate. The chill roll extension 32 is used to change the web tension.

In the illustrated embodiment of the invention, a second measuring device 52 is disposed after the chill roll extension 32. A pendulum roller 41 allows in this section an influence on the web tension. Thus, two measurements can be carried out at the same time on the measuring devices 51, 52 in the context of the method of the invention which is explained below. Since it is measured once before and once behind the chill roll, in particular temperature influences can be investigated.

If the temperature influences are to be disregarded, the measurement at the position of the measuring device 52 is to be preferred for fair and counterpressure.

Finally, the printing substrate 1 or 1 'runs on a roller of a Aufwicklungsvorrichtung 40th

Fig. 2 shows a section of an already printed substrate web 1, on which print motifs 2 at a regular distance, the repeat length Li, are located. The repeat length Li can be measured on any image section of the print motif. While in Fig. 2 the repeat length between the actual beginning and end of a print motif is marked by the double arrow arranged above the printing material web 1, the same repeat length is shown in the lower area by measurement at the respective rear image edge of the print motif. The repeat length can be determined in a manner known per se either via index marks applied to the printing substrate, by image recognition or recognition of suitable (identical) image sections of successive images.

If the repeat length Li is measured during operation of the printing machine 100 ("repeat actual length"), then the printing material web 1 is stretched, since it can be guided tightly along the numerous rolls of the printing press only with one bias.

According to the invention, the web tension is measured, for example via a web tension measuring roll 31 on the cooling roll extension 32. The repeat length measurement takes place via an optical sensor, as close as possible to the location of the web tension measurement in order to be able to detect a clear correlation between repeat length and web tension. The measured value pairs are recorded and either directly into a graphical representation Fig. 3 transmitted or cached in a data processing device. Subsequently, the web tension is varied in the area of the repeat length measurement. This can be done in the printing machine 100 according to Fig. 1 for example, by increasing the rotational speed of the chill roll extension 32.

It is advantageous to specify web tension values which lie in the region of the usual web tension in the printing process and are kept as small as possible in order to keep negligibly small changes in geometry or even irreversible changes in length of the printing material web 1, so that a linear relationship between stress and elongation is given. In packaging printing with flexible web tensions, for example, tensile forces acting on the printing material web are typical from 50 to 250 N. According to the invention, the method is then carried out, for example, five times, starting with a tensile force of 50 N, the tensile force is increased by 50 N each, until the final value of the tensile force is reached. For each preset web tension, the repeat length is measured and the value pair is stored.

The value pairs thus formed are evaluated by known regression methods. This can be done with the help of computer programs. For explanation, see Fig. 3 a graphical evaluation is shown. In the diagram, the repeat length is plotted against the web tension. Since the tensile forces are held in a region in which there is a linear relationship, ie HOOK's law applies, the web tension can be represented by the set tensile forces F1... F5. By at least two pairs of values can already be formed a regression line whose slope is inversely proportional to the modulus of the printing material. Due to tolerances, measurement inaccuracies, etc., it is advantageous to record further value pairs and then to form a regression line with increased accuracy for the plurality of value pairs.

In the case of in Fig. 3 It is sufficient to extend the regression line 120 such that it intersects the repeat length axis 110. At this point, the length defined as normalized repeat length is given for a relaxed web.

While an evaluation after Fig. 3 Provides a constant modulus of the substrate web, in addition, the temperature influence is taken into account in a variant of the method according to the invention. This is in Fig. 4 represented, where also the repeat length is plotted on the web tension. The method described above is carried out several times, wherein in each case within a series of measurements a certain temperature of the printing substrate is given. The temperature is changed for the following series of measurements. Within the measurement series, the web tension is then varied again and the repeat length is measured. A first regression line 220 results for a common operating temperature T0. If the temperature of the printing material is increased compared to the temperature T0, the slope of the Regressionsstraaden and there is a repeat length-Bahnspannungsverlauf corresponding to a regression line 221 with increased slope. If, on the other hand, the temperature of the printed matter is lowered, the gradient of the regression line 222 also decreases. For each of the regression lines 220, 221, 222 results in a different intersection point 224 with the repeat length axis, so also a different normalized repeat length.

Although the temperature change takes place in the unstretched state, a change in length, but which, in absolute terms, is much lower than at a higher web tension of the printing material. These influences can be used to determine the temperature dependence of the modulus of elasticity of the printing substrate and to be able to take it into account for the following operation. In addition, the illustration in Fig. 4 in that the temperature influence of the measurements can be minimized by the extrapolation carried out according to the invention. Insofar as the method according to the invention is used without continuous temperature measurements, it is ensured in any case that the influence of operationally occurring temperature fluctuations in the printing substrate in the inventively determined normalized repeat length value is only slight. This is particularly advantageous when the method according to the invention is carried out not only in the setup process of the printing operation, but continuously in the production run.

Here, the inventive method can be applied in the context of a Rapportlängenregelung, as in Fig. 5 is shown schematically. The printing material web 1 is initially guided through the cooling roller extract 32. By cooling the temperature of the printing material is largely homogenized. Subsequently, the printed on the substrate web 1 print motif is detected by an optical measuring system with a sensor 52 and there a repeat length Li determined (actually again the "Rapportlängenistwert").

In addition, a temperature Ti of the printing substrate 1 can be determined at the measuring location. A web tension measuring roller 71 enables the calculation of the web tension via the measurement of the bearing forces acting there. The Value pairs Li, Fi and optionally Ti are processed by a computing device and, as described above, the normalized repeat length L0 is determined. This flows into a control circuit, through which the relative speed between counter-pressure cylinder 11 and format cylinder 12 as a function of the deviation between a normal SollRapportlänge (Sollrapportlänge the web tension-free print image) and the measured normalized repeat actual length (actual Rapport length of the web tension-free print image) is set.

Fig. 5 also shows how the web tension can be varied in order to carry out the method according to the invention. Behind the web tension measuring roller 71, a motor-driven roller 72 is arranged as a preference in the web tension control loop, by the acceleration or deceleration of which the tensile forces acting on the printing material web can be changed. A specified by the control device 80 target value of the tensile force is set there via a simple control loop. Is the desired tensile force on the substrate, and thus the desired web tension achieved, the Rapportlängen- and optionally temperature measurement is performed.

As shown, the method according to the invention can either be carried out alone to determine the normalized repeat length or can be preceded by a continuously operated repeat length control method, so that in the latter case the normalized repeat length can be taken into account, optionally as a function of the temperature. However, this presupposes that a largely constant operating state is present when determining the normalized repeat length; Moreover, depending on the number of iterative steps with change in traction, a certain amount of waste has to be accepted during the setup process.

To avoid this, an execution of the statement according to Fig. 6a, 6b be beneficial. Fig. 6a shows a web tension measuring roll 71 'and two momentarily loaded guide rolls 72', 73 '. This results in a total of three track sections, wherein the tensile force F1 in the last track section is determined by the withdrawal forces. In each section are optical Sensor devices 52, 53, 54 are provided. These can be designed as cameras connected to an image recognition system. It can also cost-effective solutions are used, such as reflection light scanners, which can be detected by a gray value measurement beginning and end of a print motif.

While the force F1 is measured as an absolute value, the forces F2 and F3 can be computationally calculated from the braking or driving torques of the guide rollers 72 ', 73'.

The tensile force F3 results from the forces impressed by the guide rollers 72 ', 73' and the web stresses impressed by the previous devices, for example the cooling roller extension.

The tensile force F2 between the guide rollers 72 ', 73' is determined by the ratio of the torques M72, M73 and the forces F1, F3.

For each track section, a separate repeat length measuring device is provided, so that three measurements of repeat lengths can be performed simultaneously. With this embodiment, the method according to the invention is completely reproduced under constant operating conditions within a printing press in production mode. Three repeat length web tension value pairs are obtained at the same time, by which a normalized repeat length can be calculated without the printing and measuring operation being executed several times in succession will need. LIST OF REFERENCE NUMBERS 1, 1 ' printing material 2 print motifs 11 Impression cylinder 12 format cylinder 13 pressure roller 14 Web tension measurement roll 20 management role 21 Spherical roller 22 preference 30 drying device 31 Web tension measurement roll 32 Chill roll extract 40 Aufwicklungsvorrichtung 41 Spherical roller 51 optical measuring system 52 optical measuring system 53 optical measuring system 71, 71 ' Web tension measurement roll 72 (torque-loaded) guide roller 72 ' (torque-loaded) guide roller 73 (torque-loaded) guide roller 80 setpoint 100 press 110 Repeat length axis 120 regression line 220 regression line 221 regression line 222 regression line 224 intersection F1, F2, F3 force L _1-5 repeat length L _1-5 Normalized repeat length F _1-5 Railway Forces / web tension

Claims (15)

1. Method for operating a printing press (100), in which method a repeat length/web tension function is determined and which method contains at least the following steps:

   a) continuous printing of a printing motif (2) onto the printing-material web (1; 1') by way of at least one format cylinder (12);

   b) loading the printing-material web (1; 1') with a first web tension (F₁);

   c) measuring the web tension F_i, measuring the repeat actual length L_i and storing the repeat actual length/web tension value pair (L_i; Fi);

   d) changing the web tension F_i of the printing-material web (1; 1') and at least one repetition of step c);

   e) calculating the repeat length/web tension function from the repeat length/web tension value pairs (L_i; F_i);

   f) calculating the modulus of elasticity of the printing-material web from the repeat length/web tension value pairs (L_i; F_i),

   g) characterized in that the method is carried out multiple times at different temperatures of the printing-material web (1; 1'), in each case one data set comprising the repeat length/web tension value pairs (L_i; F_i) and the measured printing-material temperature (T_i) being stored, and in that a temperature-dependent modulus of elasticity E(T) is calculated from the data sets.
2. Method according to Claim 1, characterized in that the repeat length/web tension function is calculated by linear regression.
3. Method according to Claim 2, characterized in that the standardized repeat length (L₀) is determined graphically by determination of the point of intersection (224) of a regression line (220, 221, 222) with a repeat-length axis.
4. Method according to one of Claims 1 to 3, characterized in that in each case one data set comprising the repeat length/web tension value pairs (L_i; F_i) and the measured printing-material temperature (T_i) is stored, and in that a temperature-dependent expansion is calculated from the data sets.
5. Method according to one of Claims 1 to 3, characterized in that the web (1, 1') is divided into at least two web sections, in which there are different web tensions (F_i) of the printing-material web (1; 1') and in which in each case one repeat length L_i is measured and stored for the at least one repeat length/web tension value pair (L_i; F_i).
6. Method according to one of the preceding claims, characterized in that correction signals are determined from the repeat length/web tension function and repeat-length actual and setpoint values, which correction signals actuate means for changing the repeat length in such a way that the standardized repeat length is set within a tolerance range about the setpoint value of the standardized repeat length.
7. Method according to the preceding claim, characterized in that a printing-material temperature Ti is measured in each case with the repeat length/web tension value pairs (L_i; F_i) and a repeat-length correction value is calculated for a temperature-dependent expansion of the printing material.
8. Method according to one of the preceding claims, characterized in that the repeat-length measurement takes place via an optical sensor apparatus (51, 52, 53, 54) which detects repeating printing patterns (2) on the printing material.
9. Method according to one of the preceding claims, characterized in that the printing-material web (1; 1') is guided over at least one web-tension measuring roll (31) and the web tension (F_i) is determined from the measured bearing forces on the web-tension measuring roll (31).
10. Regulation auxiliary apparatus for a printing press for carrying out the method according to one of Claims 1 to 9, having at least:

    - means (72, 72', 73) for loading a printing-material web (1; 1') with variable web tensions (F_i) ;

    - means (51, 52, 53, 54s) for measuring a repeat length L_i of a printing motif (2) on the printing-material web (1; 1');

    - means (31, 71, 71') for measuring the web tension (F_i) ;

    - an evaluation unit for calculating the repeat length/web tension function and/or a modulus of elasticity from repeat length/web tension value pairs (L_i; F_i),

    - characterized by means for carrying out the method multiple times at different temperatures of the printing-material web (1; 1'), which means are set up for storing in each case one data set comprising the repeat length/web tension value pairs (L_i; F_i) and the measured printing-material temperature (Ti),

    - and means for calculating a temperature-dependent modulus of elasticity E(T) from these data sets.
11. Regulation auxiliary apparatus according to the preceding claim, characterized by a storage unit for storing the repeat length/web tension value pairs (L_i; F_i).
12. Regulation auxiliary apparatus according to one of the preceding claims, characterized in that a plurality of means (72, 72', 73) for simultaneously loading a printing-material web (1; 1') with different web tensions F_i and a plurality of means (51, 52, 53, 54) for measuring the repeat length L_i of a printing motif (2) are arranged along the printing-material web (1; 1').
13. Regulation auxiliary apparatus according to one of the preceding claims, characterized in that the means for repeat-length measuring is an optical sensor apparatus (51, 52, 53, 54).
14. Regulation auxiliary apparatus according to one of the preceding claims, characterized in that the optical sensor apparatus is or comprises a reflection light scanner.
15. Regulation auxiliary apparatus according to one of the preceding claims, characterized in that the optical sensor apparatus comprises an image detection unit.

Images