EP1650147A1 - Device for controlling the cutting register in a rotary printer - Google Patents

Abstract

The method is for the cut register control in a web-fed rotary printing press, whereby with the determining of the adjustment value (RI) of a cut register adjusting element allocated to a print material web, the latter adjustment value which is required to achieve a control difference (D) of zero between an actual value measurement (M) and predetermined set value (W) of the cut position is corrected in the press on the basis of a mathematical model for the error contribution of a portion of the path of the print material web not determined through the actual value measurement so that the error contribution is at least approximately compensated for.

Description

The invention relates to a method for cutting register control in a web-fed rotary printing press and to a computer program for cutting register control.

DE 199 36 291 A1 describes a method for determining the cutting positions of partial webs of a longitudinally cut printing material web in a web-fed rotary printing press, in which the partial webs are brought together into strands, folded on a funnel and finally cross-cut by a knife cylinder. In this case, the cut individual webs are referred to as partial webs and the sub-webs merged after the funnel as strands. The determined cutting positions are used to control the cut register, with a separate control loop and additionally an external control loop for the already folded strand being provided for each partial web. This should make it possible to keep the cutting positions of all partial webs of the folded strand each at a desired value.

Such a control with cascade structure is complex and requires in particular the use of a large number of sensors for detecting the actual values of the cutting position on the individual partial webs and on the folded strand. This is not only costly, but with the number of sensors used also increases the probability of failure of the cut register control, as failures of automated systems are generally caused by sensor failures in the vast majority.

Furthermore, the cutting position after folding by conventional optical means can only be detected by means of a mark on the respective outer part of each strand. A shift in the cutting position of the inner partial webs between the former and the knife cylinder is no longer measurable, which is why said cascade control of the cutting position of a strand based on the assumption that a post-folding occurs the cutting position in all partial webs of a folded strand has the same extent.

Therefore, the object of the invention is to provide a method for cutting register control in a web-fed rotary printing press, by which the cut register error, i. the deviation of the cutting position from a predetermined desired value, in the simplest possible, cost-effective and reliable manner can be minimized with high accuracy.

This object is achieved by a method and a computer program with the features of the independent claims. Advantageous embodiments are specified in the respective subclaims.

A first basic embodiment of the invention is based on the finding that in a web-fed rotary printing press the contribution of the turning unit and the folding unit to the cutting register error, ie to shift the cutting position relative to its desired position, can be predicted in relation to the contribution of the remaining units of the printing machine. In particular, it can generally be assumed that the contribution to the cutting register error arising in the units mentioned is approximately in a fixed relationship to the contributions arising in the other units of the printing press.

At least at the lying in the interior of a strand tracks the position of a cut register mark can be measured for the last time just before the merger to the strand at the beginning of the folding unit. According to the invention, the cutting position of a printing material web or partial web, to which the measured value is assigned, is therefore predicted on the basis of a measured value of the position of a cut register mark, in order to approximate the behavior of a fictitious control loop, in which the isfinrert forms the control difference for each web would be detected directly on the knife cylinder.

For this purpose, when determining the setting value of a cutting register setting element assigned to a printing material web, that set value which is necessary to achieve a control difference of zero between one of the respective printing material associated, measured Istwertmaß and a predetermined setpoint value of the cutting position would be required based on a mathematical model for the error contribution of not detected by the actual value portion of the path of the printing substrate in the printing machine corrected so that the said error contribution is at least approximately compensated. This set value is also called the first set value in the following. For the mathematical model, a linear relationship between the detected and unrecorded error contribution is considered in the first place.

A preferred procedure consists of correcting the control difference of a respective cutting register control loop resulting from said measured value by adding a control correction value in the respective control loop to the control difference between the measured actual value and a predetermined setpoint of the cutting position, which is multiplied by the difference from the uncorrected control difference and a correction term derived from the current set value of the cut register setting element is calculated with a fixed correction factor.

Such a correction is signal processing technology very easy to carry out and therefore compared to a cutting register control in which the position of a cut register mark is controlled before the strand formation without taking into account the subsequent influence of the folding unit on the cutting position, only with a very small additional cost of operations. In particular, it does not require additional sensors for measuring the position of a cut register mark on the outer web of an already folded strand.

Assuming that the disturbing effects that cause the cutting register error within the individual units of a printing press each provide an approximately constant average contribution per unit length of the distance, there is a functional relationship between the error contributions of the individual units, in which the lengths of the distances of the Substrate within the individual units. For the same error contribution per unit length Throughout the machine, the error contribution of each unit is proportional to the travel length of the stock in the respective unit.

Therefore, a preferred embodiment of the invention provides that the value of the correction factor depends on the ratio of the path length of the printing material web between the measuring location of the cut register mark and the location of the cross section to the path length of the printing material between the printing unit and the measuring location of the cut register mark, and preferably at least approximately corresponding to this ratio , Said path lengths are known as technical specification data for each printing press.

The subtraction of a correction term is used to ensure a stable behavior of the control loop despite the manipulation of the control difference. For this purpose, the difference between the instantaneous setting value of the cut register setting element and a reference value is used as a correction term, an appropriate reference value being that setting value of the cut register setting element in which the control difference has reached the value zero for the first time after the last change of the predetermined setpoint value , This criterion for establishing the reference value can be evaluated automatically without any problem. The operations for forming the correction term require only a small additional effort.

As a cut register setting element, the printing unit in which the printing material is printed, can be used by the speed of the impression cylinder is temporarily changed to adjust the cut register. However, the method according to the invention is just as applicable to printing presses in which, for the cut register setting, setting elements of a different type are provided alone or in addition to the printing unit. In a change in the speed of the pressure cylinder of a printing unit, it is expedient to simultaneously change the speed of the driven cylinder of all subsequent nips of originating from this printing unit printing material so that everywhere the same change in the peripheral speed results. This ensures that the adjustment of the cut register much faster than the web speed, namely propagates approximately with the speed of sound in the substrate, whereby the reaction time of each cutting register control loop is enormously shortened.

In a printing machine, the invention generally makes it possible to compensate for an unmeasured contribution to the cut register error. This refers in no way only to the folding unit, but in particular to the turning unit. When applied to the turning unit, the cut register setting of a turning sub-web is corrected relative to that of the direct printing web originating from the same printing web on the basis of a mathematical model for the error contribution of the additional path of the turning sub-web in the turning unit. This eliminates the need for a separate measurement and control of the turning partial web, which means a considerable effort savings. For the error contribution of the additional path of the turning sub-path is primarily a linear model into consideration.

The invention can also be used in a folding unit with several hopper levels. In this case, the correction of the cut register setting of a printing material web depends on the funnel plane in which the printing material web enters the folding unit.

A second basic embodiment of the invention is based on the recognition that in a web-fed rotary printing press, knowing the exact cutting register error of a single printing substrate, it is possible to draw conclusions about the cutting register errors of the remaining webs from the paths of the various webs, i. that the measurement of the cutting register error of a single web predicts those of the remaining webs with a certain, in many cases sufficient, accuracy on the basis of a mathematical model.

In such a mathematical model, preferably the different path lengths of the individual webs as parameters, in the simplest case in the form of a linear relationship between the cut register error of the measured web and that of another, unmeasured web.

The use of the printing unit as a cut register setting member and the consideration of the hopper plane for a correction of the respective set value of the cut register is possible in the second basic embodiment of the invention in the same way as in the first embodiment.

The particular advantage of the second basic embodiment of the invention is that it is very low effort and therefore cost feasible, since it requires only a single cutting mark sensor with associated signal processing electronics for the entire printing press, which compared to the cutting mark measurement on each track or sub-web an enormous Reduction in the scope of the sensors and the downstream signal processing electronics and thus an enormous cost savings means. It goes without saying that with the omission of a single measurement on each track, a potentially greater residual error is to be accepted. For applications with not too high accuracy requirements, the accuracy of the scheme may still be sufficient.

A further advantageous embodiment of the invention is based on the finding that at constant operating speed of a printing press the cutting position remains almost constant and therefore for a given speed with a static setting of the cut register, so theoretically without a cut register control, a sufficient accuracy of the cutting position can be achieved can. However, in the case of changes in speed, that is to say in particular when starting from the set-up speed to the continuous printing speed and when returning to the set-up speed, a comparatively large dynamic cutting register error occurs during the course of the printing operation. However, this dynamic cutting register error has a characteristic time profile for a given time course of the operating speed, which is well reproducible given otherwise constant operating parameters of the printing press.

According to the invention, therefore, in addition to the explained cut register control, a predetermined speed function describing a temporal variation of the operating speed of the printing machine proceeding from a predetermined initial value is assigned a cut register function which describes a temporal variation of another set value of the cut register. In a variation of the operating speed of the printing press according to the predetermined speed function of this second set value of the cut register is continuously changed time-synchronized according to the associated cutting register function. In this case, the cutting register function is empirically selected such that it counteracts a change in the actual value of the cutting position as a result of the change in the operating speed. The second set value is available to the cut register control for determining the first set value, so that already part of the determined control error can be compensated in advance. Consequently, according to this embodiment of the invention, only a residual error must be corrected by means of the first set value, as a result of which a faster cut register control is available.

Assuming that a printing press represents an approximately linear system with respect to the cutting register, the negative value of a function representing the time variation of the actual position of the cutting position from the value at the predetermined initial operating speed of the printing machine can be used as the cutting register function describes the case that a variation of the operation speed according to the predetermined speed function is performed while keeping the set value of the edit register constant.

Such a function can be determined by measurements, ie by changing the operating speed according to the speed function of interest for the actual operation and thereby measuring the actual value of the cutting position with constant cutting register setting by measurements, either manually on the basis of samples taken or sensorially by means of suitable marks on the printing material , For simplification, it can then be used as a cutting register function a mathematical approximation function be used for the metrologically determined course.

It is advantageous to store at least a portion of the parameters of such an approximation function in a memory so that they can be displayed to the operator of the printing press and manually changed by him to create the possibility that when a drift of the cutting position in the course of success following printing processes a suitable adaptation of the cutting register function can be made. The use of a mathematical approximation function whose shape can be varied by a few adjustable parameters is of great advantage in this regard.

For the real printing operation, it is typical that a variation of the operating speed is not irregular or arbitrary, but that the time course of the speed is divided into different characteristic sections. These sections are then also associated with characteristic sections of the cut register function.

In particular, a real speed function typically starts from a phase of constant initial speed, followed successively by a constant rate increase rate, a constant speed over a variable length interval but a predetermined minimum length, and a constant rate drop rate. A phase of constant final velocity generally completes the velocity function.

In this case, the associated cut register function has a constant first value during the constant initial phase of the speed function. During the constant phase of higher speed, it reaches a constant second value. In the rising phase of the speed, it has a curved course, which may contain a maximum that exceeds the constant second value in absolute value. This results from a characteristic overshoot of the cut register error observed with a linear increase in velocity in the case of a constant slice register setting.

The cut register function associated with the speed function described above, which has a constant first value during the constant initial phase of the speed function, achieves a constant second value not only during the higher speed constant phase but also during the constant final phase of the speed, a constant third value. In the declining velocity phase between the constant second value and the constant third value, it then proceeds approximately linearly.

If a press has multiple cut register adjustment controls, as is the case with newsprint presses, where multiple simultaneous printed webs are merged into a single product, each of these adjusters may be assigned an individual cut register function to accommodate different effects of machine speed change different path guides and path lengths of the individual webs or the resulting by longitudinal section and folding partial webs and strands in the context of the possible compensate.

• Fig. 1 eine schematische Seitenansicht einer Druckmaschine mit zwei Druckeinheiten,
• Fig. 2 eine Darstellung des erfindungsgemäßen Verfahrens als regelungstechnischer Signalflussplan,
• Fig. 3 eine schematische Teilseitenansicht einer Druckmaschine entsprechend einer ersten Ausführungsform der Erfindung,
• Fig. 4 Zeitverläufe des Schnittregisterfehlers bei einer Variation der Geschwindigkeit einer Druckmaschine für verschiedene Regelkreiseinstellungen,
• Fig. 5 eine schematische Teilseitenansicht einer Druckmaschine entsprechend einer zweiten Ausführungsform der Erfindung,
• Fig. 6 den zeitlichen Verlauf der Betriebsgeschwindigkeit, des Schnittregisterfehlers und der Schnittregistereinstellung gemäß einer Ausführungsform, und
• Fig. 7 den zeitlichen Verlauf der Schnittregistereinstellung gemäß einer Ausführungsform in Form einer Näherungskurve.

Hereinafter, embodiments of the invention will be described with reference to the drawings. In these shows

• 1 is a schematic side view of a printing machine with two printing units,
• 2 shows an illustration of the method according to the invention as a control-technical signal flow diagram,
• 3 shows a schematic partial side view of a printing press according to a first embodiment of the invention,
• 4 shows time profiles of the cutting register error with a variation of the speed of a printing machine for different control loop settings,
• 5 shows a schematic partial side view of a printing press according to a second embodiment of the invention,
• FIG. 6 shows the time profile of the operating speed, the cutting register error and the cut register setting according to an embodiment, and FIG
• Fig. 7 shows the time course of the cut register setting according to an embodiment in the form of an approximate curve.

First, a brief overview of the path of a printing material in a printing press will be given with reference to FIG. 1, as far as it is of importance for the present invention. As shown in FIG. 1, a printing press usually has a plurality of printing units, in each of which a printing material web is printed. In Fig. 1, only the printed in the printing unit 1 web 2 is shown after leaving the printing unit 1 for simplicity.

This web 2 is first cut longitudinally into two partial webs 3A and 3B like the webs coming from the other printing units. Of the partial webs 3A and 3B, a partial web 3B is turned in a turning unit 4, before the two partial webs 3A and 3B are brought together with other printing units, not shown partial webs to form a strand 5 and this is folded at a hopper 6. By folding the funnel 6, the strand 5 is rotated by 90 ° and then runs to a knife cylinder 7, where it is cross-cut into individual sections. The position of the cut must be matched to the position of the printed image in order to maintain a constant, predetermined distance of the printed image from the cut edges in the longitudinal direction.

In order to set the cutting register, ie the cutting position with respect to the printed image, the web 2 or the partial webs 3A, 3B and optionally additionally the strand 5 can be guided over rollers which can be displaced transversely to the transport direction, with the aid of which the printing unit 1 to to the knife cylinder 7 to be traversed path length can be selectively varied. Another possibility is to adjust the angle of rotation of the printing cylinder of the printing unit 1 to at the same Path length of the printing unit 1 to the knife cylinder 7 to move the printed image relative to the cutting position. The latter has the advantage that additional cutting register adjusting elements are not required for all partial webs, but only for the partial webs turned in the turning unit 4. Although the applicability of the method according to the invention does not depend on the type of setting elements with which the cut register setting is realized, the following is based on the use of the printing unit 1 for the cut register setting.

To control the cut register, before entering the folding unit, i. before merging the partial webs to a strand 5 per partial web 3A, 3B, an optical sensor 8 is arranged, which detects the position of a cutting register mark on the partial web 3A, 3B. For example, the knife cylinder 7 may be equipped with an incremental encoder which supplies a clock signal having a predetermined number of pulses and a reference pulse per revolution of the knife cylinder. In this case, when the cut register mark appears on the sensor 8, the number of such pulses generated since that time since the last reference pulse can be used as a measure of the position of the cut register mark. Such a measured position of a cutting register mark provides a measure of the actual value of the cutting position, i. represents the expected distance of the cut from the mark and can be used to control the cut register of the respective substrate web.

The path of the printing material web 2 or the part webs 3A, 3B cut therefrom from the printing unit 1 to the location of the cutting register measurement by the sensor 8 is marked as L1 in FIG. As L2 in Fig. 1, the distance of the printing material in the form of the strand 5 from the location of the cut register measurement by the sensor 8 to the knife cylinder 7 is marked.

It is understood that when using the measuring signal M of the sensor 8 as the actual value of the cutting position in a control loop for cutting control a systematic error is committed by the contribution of the distance component L2 is not taken into account for the cutting register error. After the route L2 in practice is quite similar in length to the line L1, the effectiveness of such a cut register control is necessarily limited from the outset.

The procedure according to the invention for improving the cut-off register control on the basis of a current value detection before the folding unit according to FIG. 1 is shown in FIG. 2 in the form of a control-technical signal flow diagram which shows a single control loop. In this case, such a control loop is provided for each partial track 3A, 3B.

In FIG. 2, G1 (p) denotes the transmission behavior of the path component L1. The input signal of this transfer element G1 (p) is the set value RI of the edit register. The printing substrate is subject to disturbances along the line segment L1, which lead to a dynamic shift in the cutting position, in particular when the operating speed of the printing press changes. These disturbances are taken into account in FIG. 2 by adding a disturbance Z1 to the output signal of the transmission element G1 (p). The superimposition of the output signal of G1 (p) and Z1 gives the measured value M for the cutting position which the optical sensor 8 arranged between the turning unit and the folding unit supplies.

The track share L1 is followed by the track share L1 in the folding unit. In FIG. 2, G2 (p) denotes the transmission behavior of the path component L2. The input signal of this transmission element G2 (p) is said measured value M for the cutting position at the end of the path component L1. The printing material web with the measured value M is subject to further disturbing influences along the path L2, which lead to a further dynamic displacement of the cutting position, in particular given a change in the operating speed of the printing press. These further disturbances are taken into account in FIG. 2 by the addition of a further disturbance Z2 to the output signal of the transmission element G2 (p). The result of this addition is the actual distance Y of the cut register mark from the cut on the knife cylinder 7.

In a conventional closed-loop control circuit, the measured value M detected by the sensor 8 is subtracted from a setpoint value W which can be set by the printer and the control deviation D thus formed is fed to a controller having the transmission behavior R (p). In this case, the position of the cut register mark on the measured substrate part web 3 with respect to the rotational angle position of the knife cylinder 7 is meant by said desired value W. The control correction value KW, which according to FIG. 2 is added to the control difference D, is equal to zero in the conventional control circuit considered hitherto, ie. the branches of the signal flow diagram according to FIG. 2 serving to form the control correction value KW do not exist there. The output signal of the controller R (p) is the current set value RI of the cut register setting member formed in the example under consideration for the straight-ahead part sheet 3A by the printing unit 1 itself and for the reversing part sheet 3B by an additional adjusting member not shown in the figure is supplemented.

It will be understood that the conventional control circuit described above merely aims to maintain a correspondence of the measured value M with the target value W, so that the error of the actual distance Y between the cut register mark and the cut on the knife cylinder 7 is substantially due to the disturbance contribution Z2 of the link portion L2 is determined. In practice, however, the route length L2 is of the same order of magnitude as the route length L1, and this also applies to the respective interference contributions Z1 and Z2, so that the effectiveness of the regulation as a whole is in need of improvement altogether.

According to the invention, it is now assumed that the contribution of the path portion L2 to the cut register error is in a fixed ratio F to that of the path portion L1, and that this ratio F is even approximately given by the aspect ratio L2 / L1. As a result, if Y is measured instead of M, then an existing control difference WY would be greater by a factor of 1 + L2 / L1 than the difference D = WM. While maintaining the measurement of M, this can be taken into account by purely mathematical additional operations in the control loop, which in the signal flow diagram of FIG represent additional signal path through which an additional contribution with the value FD = (L ₂ / L ₁ ) .D is generated from the conventional control difference D and added to D.

If the characteristic correction value denoted by KW in FIG. 2, added to D alone in the previously described manner, ie without the signal flow branches shown in FIG. 2 above the two transmission elements F = L2 / L1 and R (p), would result a potentially unstable behavior of the control loop. Assuming, for example, L2 / L1 = 1 and thus Z1 = Z2, the result would be a value KD = 2D = -2Z1 for the corrected control difference KD when a disturbance Z1 = Z2 occurs and, consequently, an override of the setting value RI of the edit register Double the value that would be needed for a control difference D = 0. This would cause as large a control difference D as the original, but with opposite sign. This would in turn lead to a corresponding override of RI in the other direction, which would create a vibration in the control loop, in which the error of the actual cutting position Y would fluctuate between zero and 2Z1. It is understood that such vibrations can potentially also increase in amplitude.

In order to avoid this, the portion of the control difference D which is added to the uncorrected control difference D weighted by the correction factor F = L2 / L1 is subtracted, prior to the weighting, the previous change ΔRI in the cut register set value RI. In this case, the previous change ΔRI means the difference between the current value of RI and a reference value RB, which is the value of RI at the first coincidence of the measured value M with the desired value W after a change of the setpoint W.

In the previous example with L2 / L1 = 1, in a stable state with M = W RB = RI, ie ΔRI = 0, would occur. If Z1 = Z2, RI would initially override due to KD = 2D = -2Z1 a value ΔRI = -2Z1 present. The override of the regulator would be like initially previously mentioned will cause a control error as great as the original one, but with opposite sign, but the difference D-ΔRl before weighting with the factor L2 / L1 would now compensate for the overshoot of D, thus preventing the ringing of a locked loop. In this case, the value ΔRI includes the corrections made to date by the control loop of the cut register setting RI.

The set value RI of the cut register must change even if the set value W is changed. However, this does not represent a response of the control loop to disturbances Z1 and Z2, and therefore, after settling to a steady state following a change in W, the new value of RI is stored as reference value RB of the cut register setting for further control.

As those skilled in the art will appreciate, the foregoing stability considerations do not consider the dynamic properties of the involved transfer elements R (p) and G1 (p). They are so far simplistic and therefore not to be understood as a complete stability analysis of the control loop. Rather, they should only explain in principle the meaning of the subtraction of the correction term ΔRI.

To illustrate a further aspect of the invention, Fig. 3 is a schematic partial side view of a printing machine, ie an enlarged detail of Fig. 1, in which details of the turning unit 4 and the folding unit can be seen, according to a first embodiment of the invention. The reference numerals of Fig. 3 correspond to those of Fig. 1, wherein only one printing unit 1 is shown, in which the printing substrate 2 is printed. Two further printing material webs 12 and 22 come from other printing units, not shown, which are located to the right of the printing unit 1. Because of the basic agreement of the representation of FIG. 3 with that of FIG. 1, a new description of the elements contained therein and already mentioned with reference to FIG. 1 is unnecessary.

The printing material web 2 is cut in length on a longitudinal cutting cylinder 9 into two partial webs 3A and 3B, namely a straight-ahead part web 3A and a turning sub-web 3B. The straight-ahead part track 3A runs directly into the folding unit, while the turning part track 3B is previously deflected in the turning unit 4 on schematically indicated turning bars 10 and thereby turned. It is clear that the path of the turning partial path 3B in the turning unit 4 is thereby significantly longer than that of the straight-ahead part track 3A, and that the turning partial path 3B is exposed to additional frictional forces and consequently greater elongation as a result of the deflection at the turning bars 10.

For measuring a cut register mark on the straight-ahead part track 3A, after the turning unit 4, a sensor 8 already shown in FIG. 1 is arranged, which supplies a measured value M for the cutting position of the straight-ahead part track 3A. Similar sensors are also provided for the straight-ahead partial webs of the further printing substrate webs 12 and 22, which are likewise cut longitudinally, but are not shown in FIG. 3 for the sake of clarity.

In order to regulate the cutting position of all partial webs, just as many sensors 8 as partial webs and just as many individual control loops would be necessary. However, if the additional contribution to the cutting register error experienced by a turning sub-web 3B compared to the associated straight-ahead web 3A is predictable, then it suffices to measure only the position of the cutting mark on the straight-ahead web 3A and the cut register setting of the turning sub-web 3B according to said prediction of the straight-ahead part track 3A in order to achieve a sufficient accuracy of the cutting position in both partial webs 3A and 3B.

In general, it can be assumed that the additional expansion of the turning partial web 3B in the turning unit 4 is in a fixed relationship to the elongation of the straight-ahead part track 3A between the longitudinal cutting cylinder 9 and the sensor 8, so that said correction is easily executed and, for example, in the addition a constant or linearly dependent on the cut register setting of the straight-ahead part of the sheet 3A correction value may exist.

It is understood that different cut register settings of the straight-ahead part track 3A and the turning part track 3B require separate adjustment elements for both partial webs. This can be realized, for example, in that the straight-ahead part web 3A is adjusted solely by means of the printing cylinders of the printing unit 1, and that for the correction of the turning sub-web 3B a displaceable register roller is provided as an additional actuating element, by means of which for the turning sub-web 3B a deviating from the straight-ahead part web 3A Setting can be made.

If instead of a sensor 8 and a separate control loop per sub-web only a single sensor 8 and a single loop with correction per printing material 2, 12, 22 is required, then this means a total reduction of the sensory and signal processing overhead. This prediction of the additional error contribution of the turning unit 4 in the turning partial path 3B can be combined with the previously explained prediction of the error contribution of the folding unit in all partial webs, but also be applied independently of the latter.

Not shown by a separate figure is an aspect of the invention which relates to complex folding units having a plurality of successive hopper planes. In this case, the extent of the necessary correction of the cut register setting value obviously also depends on which funnel plane a printing material web or partial web enters into the folding unit, so that the funnel plane must enter into the determination of the correction. In this case, the path length-dependent correction described above already implicitly takes into account the funnel plane in that the path length in the folding unit naturally depends on the funnel plane in which a printing material web or partial web enters the folding unit.

A correction that is specifically dependent on the funnel level can be added to a path-length-dependent correction as an additional measure if required, as well as replace it for simplification. In the simplest case, a manually adjustable correction value can be provided for each hopper level which is additively added to the setting value of the cut register of all printing material webs running across the respective hopper level. However, the funnel plane-specific correction value could also be selected in functional dependence on the cut register settings of the printing material webs running over the respective funnel plane. In particular, it could be a linear function of the respective slice register setting.

The effect of the method of the invention is illustrated by FIG. 4, which exemplifies some of the timing errors of the cut register error as measured in a trial of the present invention for a typical velocity profile of the operation of a linear scale printing machine. In this case, said speed profile is shown in dashed lines and designated v. It starts from a relatively low speed, namely the set-up speed of the printing press, then increases linearly to the printing press, it remains constant for a certain time and then drops linearly down to the set-up speed.

The curve marked ΔY0 shows the time course of the cutting register error which results in the velocity profile v, if no countermeasures are taken. It can be seen that the error increases nonlinearly during the linear velocity increase, flattening out after reaching the phase of constant print speed and also remains at least approximately constant, falls nonlinearly during the linear velocity drop, and changes to negative region approximately when the setup speed is reestablished.

The curve marked ΔY1 shows the time course of the cutting register error which results in the velocity profile v when a conventional control with actual value measurement is applied before the folding unit without taking into account the error contribution of the folding unit. This conventional control would correspond in the representation of FIG. 2 to a weighting factor F = 0. The occurring maximum value of the error in this case, although only about 35% of that, which can be observed without any regulation on the curve ΔY0, but the improvement of this result is obvious.

The curve marked ΔY2 shows the time course of the cutting register error, which results in the velocity profile v, when a control according to the invention with actual value measurement before the folding unit and taking into account the error contribution of the folding unit by correction of FIG. 2 with a weighting factor F = L2 / L1 corresponding to Ratio of the Wegstreckenanteile L2 and L1 of the substrate is used in the printing press. In the example considered, the weighting factor F = L2 / L1 has a value of about 0.35. It can be seen that the maximum value of the cutting register error was significantly reduced by the invention in comparison with the conventional control, namely to only about 15% of that of the control curve ΔY0 that applied without regulation.

The curve marked ΔY3 shows the time course of the cutting register error, which results in the velocity profile v, when a regulation according to the invention with actual value measurement before the folding unit and taking into account the error contribution of the folding unit by correction with a wrong weighting factor F is applied. The weighting factor F corresponds to the curve .DELTA.Y3 not the ratio L2 / L1 of the path portions L2 and L1 of the printing substrate in the printing press, but is significantly larger than this ratio, namely twice as large. This means that the curve ΔY3 illustrates the effect of an incorrect parameterization of the control loop from FIG. 2. In this case, in comparison with the operation without regulation, a maximum value of the cut register error of approximately -50%, which is lower in absolute value than the value achieved with a conventional control at the curve ΔY1, results.

The curves shown previously in FIG. 4 are to be understood as purely exemplary. In particular, the course of the unregulated dynamic cutting register error ΔY0 depends on the printing machine under consideration and on the printing substrate for a given course of the operating speed v. There are also qualitative differences in the shape of the curve ΔY0 possible, of course also result in qualitative differences in the shape of the other curves. However, the basic effectiveness of the invention, which is clearly demonstrated by the test results shown in Fig. 4, does not depend on a particular waveform of the unregulated dynamic cut register error ΔY0.

It is particularly advantageous that the application of the method according to the invention to the folding unit in comparison to a conventional cutting register control without consideration of the folding unit requires only a small additional effort, which is predominantly in the field of programming in a digital realization of the control loop. The application of the invention to the turning unit provides even compared to a conventional cut-off register control in which are measured at all sub-webs Schnittregistermarken, a considerable effort reduction.

Fig. 5 shows a schematic partial side view of a printing press according to a second embodiment of the invention, which largely coincides with the first embodiment shown in Fig. 3, so that a re-description of the elements contained therein and already mentioned with reference to FIG. 3 is unnecessary and only the Differences need to be explained. The reference numerals of FIG. 5 correspond as far as possible to those of FIG. 3.

In contrast to FIG. 3, only a single sensor 8 'is located just in front of the knife cylinder 7 for measuring a cut register mark, which delivers a measured value M' for the cutting position of the outermost web of the entire folded strand 5. Other cutting position sensors are not provided.

Assuming that the turning partial web 3B emerging from the printing material web 2 forms the outermost layer of the strand 5 on which the cut register mark detected by the sensor 8 'is printed, the measured brand position can only be used directly as an actual value for the regulation of the cutting register of this partial web 3B the cutting position can be used. However, it is known how long the path of the partial web 3B of the printing unit 1 to the knife cylinder 7 is a total, and by how much the distances traveled by the other partial webs in the printing press differ from the path length of the partial web 3B.

Assuming, to a first approximation, that the total elongation of a partial path is proportional to its path length, the section register error of each other partial path can be determined in a simple manner from the section register error measured with the aid of the sensor 8 'on the outer partial path 3B. due to a linear relationship, predict. Thus, the cut register error of the other web 3A cut from the same web 2 is less because its travel is shorter while the errors of all other webs are greater since the webs 12 and 22 from which these webs are cut are farther away, as shown in FIG 5 are printing units, not shown, and thus have a longer path, provided that the distance between the other printing units of the printing unit 1 is greater than the additional path portion of the turning partial web 3B relative to the straight-ahead part track 3A.

Of course, the accuracy of the mathematical model can be increased if necessary over the aforementioned linear approach by nonlinear terms, for example in the form of a polynomial theorem.

In any case, the reduction of the cut register sensor to only a single sensor 8 'on the knife cylinder 7 provides an enormous amount of hardware expenditure, while the mathematical modeling of the dependence of the cut register error of the unmeasured sub-webs from that measured by the single sensor 8' on the sub-web 3B Error purely in the field of software and therefore can also be easily adapted to different types of printing presses. The embodiment of Fig. 5 is of particular interest for applications where less accuracy is required but low cost.

FIG. 6 shows a speed profile from set-up operation via the print run to shut-down of the printing machine. In setup mode, a press usually runs at a relatively low speed to attack To keep paper waste low. Once the machine has been set up, the speed is increased to the machine's production speed, which increase can not be instantaneous, but occurs continuously with a usually constant rate of increase fixed by the electronic control of the machine. This time course of the operating speed of a printing press is shown in FIG. 6, the dashed curve 23 again, wherein the phase of constant Einrichtgeschwindigkeit with A and the phase linear velocity increase is marked with B. The scaling of both axes is linear in FIG.

If the printing speed is reached, it is maintained in a phase C until an intended number of printed products is produced. This phase C is shown greatly shortened in Fig. 6 compared to the real printing operation. Subsequently, the speed in a phase D is again reduced with a constant rate of decay fixedly determined by the electronic control of the machine until a predetermined final speed, which usually corresponds to the set-up speed, and thus the last operating phase E is reached.

If the slice register adjustment is made at setup speed and then maintained during the previously described variation in velocity during phases B through E, then a slice register error, i. a deviation of the cutting position from its nominal value, as shown by the curve 24 in Fig. 6. Also with regard to the edit register, the scaling in FIG. 6 is linear.

As long as the set-up speed has not yet left, the cut register error is almost zero, ie only slight fluctuations of the curve 24 near the zero position can be detected in phase A. During the increase in the velocity in phase B, the cut register error increases sharply, its time course being clearly nonlinear and significantly flattening as the rise time increases despite the rate of increase in the rate being constant.

At the transition of the velocity increase to the constant pressure velocity phase C, the cut register error decreases almost abruptly to a certain extent below the value reached at the end of phase B and then remains during phase C apart from minor variations comparable to those of phase A, almost constant. As mentioned above, the phase C in Fig. 6 is shown greatly shortened, but in view of the approximate constancy of the cut register error at this stage, this is not relevant to the understanding of the invention.

If the speed in phase D is reduced starting from the constant value of phase C at a constant decay rate, then the clipping register error also drops, but not vice versa to its course in the speed increase, but much faster. In this case, even the zero line is exceeded and the cut register error reaches at the end of the phase D a negative value, which is in the same order of magnitude as the approximately constant positive value in the phase C. In a first approximation, the profile of the cutting register error in the phase D as be viewed linearly.

When the velocity has reached its final value and is held constant again in phase E, then an abrupt drop in the absolute value of the cut register error is observed, which then remains almost constant at a now negative value. This also applies if the final speed corresponds to the initial speed. The press is thus a time varying system with respect to the cut register error.

The basic idea of the invention is based on the fact that the cutting register error, which was set to zero by the operator of the machine in phase A, can be compensated for, ie kept at a value of zero, during the passage of a predetermined time course Machine speed, the cut register setting is selectively varied, in accordance with the negative value of previously empirically determined curve 24. This reflection of the curve 24 on the time axis is shown in Fig. 6 as a curve 25.

Since the curve 24 is undoubtedly subject to certain stochastic fluctuations, it would not make sense to actually use the negative measured curve 25 to compensate for the cut register error. Rather, the curve 25 can be described relatively accurately with a mathematical approximation function, and this must likewise be defined in sections according to the subdivision of the curves 23 and 24 into clearly distinguishable sections.

In FIG. 6, such an approximation function is shown by way of example as a curve 26. This approximation function 26 is zero in phase A, has a curved course in phase B and at the beginning of phase C, which has an absolute maximum within phase B. It can be approximated by a cubic polynomial, for example, with good accuracy. In the course of phase C, it goes into a constant value, which lasts relatively long in real printing operation compared to the curved initial region of this phase. In phase D, the approximation function 26 is linear, changing the sign. At the beginning of phase E, it returns to a constant value, which is maintained as long as necessary.

FIG. 6 shows purely by way of example some guide values for parameters for characterizing the curve 26. Thus, the time period from the beginning of phase B to the absolute value maximum is about 50-80% of the total duration of phase B. The transition range at the beginning of phase C until a constant value is reached takes about 10-30% of the length of phase B. The magnitude of the magnitude maximum in phase B is approximately 100-150% of the constant value reached during phase C. The magnitude of the constant end value with reversed sign in phase E is in the range of 50-300% of the constant value reached during phase C. The range in which the slope of the curve 26 lies within the phase D is clear from the other parameters.

For clarification, the compensation curve 26 for the phases of startup B, the continuous pressure C and the outlet D in FIG. 7 is again shown alone. Is the basic curve in the form of a section-wise defined function using compensation polynomials for the phase B and the start region of the phase C and of straight sections for the remaining region of the phase C and the phase D, the compensation curve 26 can be completely described by a total of five parameters. These are the position of the amount maximum in phase B as part b1 of the total startup time B, the duration of the transition in the B phase. Phase C as proportion c1 of the total printing time C, the value S of the cutting register setting in the stationary region of the printing time C, the ratio b2 of the height of the maximum amount of the cutting register setting in the phase B to the value S, and the ratio d2 of the final value of the cutting register setting at the end of the Phase D to value S. where b2 ≥ 1 and d2 <0.

It should be noted that, for the mathematical description of the compensation curve 26, a total of more than the stated parameters are required if the phase B and the start region of the phase C are represented, for example, by two cubic polynomials. The adaptation of all curve parameters, i. However, in the case of polynomials of all polynomial coefficients, to the said adjustable parameters can be made by the control device or control device of the printing press automatically according to predetermined mathematical rules.

If the printer determines by control measurements during the printing operation that the compensation effect in one or more phases is insufficient, ie that an impermissibly large cut register error occurs at the compensation curve 26 specified at the beginning of the printing operation, then it can use one or more of the parameters b1, c1, Change S, b2 and d2 by manual intervention. This change acts directly on the current printing operation and is stored for the next run of the printing press as a new waveform of the compensation curve 11. In this way, the shape of the compensation curve 11 can, if necessary, track slow changes over time in the behavior of the printing press, ie a long-term drift of the dynamic cut register error.

It is understood that the duration of the setup phase A and the duration of the final phase E are arbitrary, because the compensation begins only with the entry into the phase B and after the end of the phase D, the cut register setting d2xS reached there is no longer changed.

The waveforms previously shown in Figures 6 and 7 are to be understood as purely exemplary. In particular, the course of the dynamic cutting register error depends on the individual printing press, as well as the substrate and the path lengths, for a given course of the operating speed. Not only are quantitative differences in the values of the characteristic parameters, but also qualitative differences, i. a shape of the required compensation curve 26, which deviates significantly from the course shown as an example, is possible. In any case, however, it can be assumed that the curve shape 24 of the cutting register error for a given speed curve 23 is a reproducible characteristic of the respective printing press and the printing material used, and that it is generally sufficiently accurately describable by a section-wise defined approximation function 26.

The method according to the invention can also be used if a printing machine is to be operated optionally with different rates of increase and decrease of the speed and / or with different speeds of production. In this case, for each possible speed curve 23, an associated compensation function 26 must be stored or the existing one spread differently.

Claims (28)

A method for cutting register control in a web-fed rotary printing press, merged into the substrate webs to at least one strand and the strand is folded and cross-cut after folding, wherein measured before the merging of the printing material to the at least one strand positions of printed Schnittregistermarken and in control loops as measures of actual values of Cutting positions are used for cutting register control, characterized in that when determining a first set value (R1) of a printing material (2, 3A, 3B) associated Schnittregister-Einstellelementses that first set value for achieving a control difference (D) of zero between one of respective measured material web (2,3A, 3B) associated, measured actual value (M) and a predetermined desired value (W) of the cutting position would be required on the basis of a mathematical model for the error contribution of not detected by the actual value measurement Ant eils the path of the printing substrate (2,3A, 3B) is corrected in the printing press so that said error contribution is at least approximately compensated. Method for cutting register control according to Claim 1, characterized in that the mathematical model has a linear relationship between the error contribution of the portion of the path of the printing material web (2,3A, 3B) in the printing press not detected by the actual value measurement and the control difference (D) between the Substrate (2,3A, 3B) associated, measured actual value (M) and a predetermined setpoint (W) provides. A method for cutting register control according to claim 1 or 2, characterized in that in the control loops in each case to the control difference (D) between the the printing material (2,3A, 3B) associated, measured actual value (M) and the predetermined set value (W) of the cutting position Rule correction value (KW) is added by multiplying the difference from the uncorrected control difference (D) and one of the current first set value (RI) of the cut register setting element derived correction term (ΔRI) is calculated with a fixed correction factor (F). A method for cutting register control according to claim 3, characterized in that the value of the correction factor (F) of the ratio (L2 / L1) of the path length (L2) of the printing substrate (2, 3A, 3B, 5) between the measurement location of the cut register mark and the location of Cross-section to the path length (L1) of the printing substrate (2, 3A, 3B, 5) between the printing unit (1) and the measuring location of the cut register mark depends. A method for cutting register control according to claim 4, characterized in that the correction factor (F) at least approximately the ratio (L2 / L1) of the path length (L2) of the printing material (2, 3A, 3B, 5) between the measurement location of the cut register mark and the location of Cross-section corresponds to the path length (L1) of the printing material (2, 3A, 3B, 5) between the printing unit (1) and the measuring location of the cut register mark. A cut-off control method according to any one of claims 3 to 5, characterized in that the correction term (ΔRI) is the difference between the current first set value (RI) of the cut register setting element and a reference value (RB). A method of cutting register control according to claim 6, characterized in that the reference value (RB) is the first set value (RI) of the cut register setting element in which after the last change of the predetermined set value (W) the control difference (D) sets the value for the first time Has reached zero. A method for cutting register control according to one of claims 1 to 7, characterized in that the printing unit (1) in which the printing material (2, 3A, 3B, 5) is printed, is used as a cutting register adjustment element, by temporarily adjusting the cutting register the speed of the impression cylinder is changed. Method for cutting register control according to claim 8, characterized in that at a change in the speed of the printing cylinder of a printing unit (1) at the same time the speed of the driven cylinder of all subsequent nips of this printing unit (1) originating printing substrate (2,3A, 3B) changed so will result in the same change in peripheral speed everywhere. A method for cutting register control according to one of claims 1 to 9, characterized in that the printing material webs (2) are cut lengthwise into partial webs (3A, 3B), which before the merger to the at least one strand (5) partially in a turning unit ( 4), and in that the cut register setting of a turned partial web (3B) compared to that of the non-turned partial web (3A) originating from the same printing web (2) is based on a mathematical model for the error contribution of the additional path of the turned partial web (3B). in the turning unit (4) is corrected. Method for cutting register control according to claim 10, characterized in that the mathematical model for the error contribution of the additional path of the turned partial path (3B) in the turning unit (4) has a linear relationship between this error contribution and the error contribution of the path of the non-turned partial path (3A). between the location of the longitudinal section and the measuring location of the cut register mark on the non-turned part track (3A). A method for cutting register control according to one of claims 1 to 11, characterized in that in a folding unit with a plurality of levels of funnels (6) of the first set value (RI) of a printing material (2, 3A, 3B) associated cutting register adjustment element depending on the funnel plane , in which the printing material web (2,3A, 3B) enters the folding unit, is corrected. A method for cutting register control in a web-fed rotary printing press, in which printed material webs merged into at least one strand and the strand is folded and cross-cut after the folding, wherein after merging the printing material to the at least one strand measured the position of at least one printed Schnittregistermarke and in at least one control loop Measurement of the actual value of the cutting position for cutting register control is used, characterized in that the measured position of the mark for the cut register control of those printing material on which the mark is printed, is used directly as the actual value of the cutting position, and that for the Schnittregisterreglung the other printing material webs Actual value of the cutting position of the respective web from the measured position of the mark is calculated on the basis of a mathematical model, which shows the different paths of the different paths through the D consideration machine. A method for cutting register control according to claim 13, characterized in that enter into the mathematical model, the different lengths of the paths of the various webs through the printing machine as a parameter. A method for cutting register control according to claim 14, characterized in that the mathematical model provides a linear relationship between the measured position of the mark and the respectively calculated actual value of the cutting position of one of the other webs, in which the lengths of the paths of the web on which the mark is printed is, and enter the respective other web in the printing press. A method for cutting register control according to any one of claims 13 to 15, characterized in that the printing unit (1) in which the printing material (2, 3A, 3B, 5) is printed, is used as a cutting register adjustment element by temporarily to adjust the cut register the speed of the impression cylinder is changed. A method for cutting register control according to claim 16, characterized in that at a change in the speed of the printing cylinder of a printing unit (1) at the same time the speed of the driven cylinder of all subsequent nips of this printing unit (1) originating printing substrate (2,3A, 3B) changed so will result in the same change in peripheral speed everywhere. A method for cutting register control according to one of claims 13 to 17, characterized in that in a folding unit with a plurality of levels of funnels (6) of the first set value of a printing material (2, 3A, 3B) associated cutting register adjustment element depending on the funnel plane, in which the printing material web (2,3A, 3B) enters the folding unit, is corrected. Method for cutting register control according to one of the preceding claims, characterized in that a predetermined speed function (23) describing a temporal variation of the operating speed of the printing press proceeding from a predetermined initial value comprises a cutting register function (26) representing a temporal variation of a second setting value of the cutting register is described, and that in a variation of the operating speed of the printing press according to the predetermined speed function (23), the second set value of the cut register is continuously time synchronized according to the associated cut register function (26) is changed, wherein the cut register function (26) is empirically selected so that it counteracts a change in the actual value of the cutting position as a result of the change in operating speed. A method for cutting register control according to claim 19, characterized in that the negative value of a function is used as a cutting register function (26), which describes the time variation of the actual value of the cutting position with respect to the value present at the predetermined initial value of the operating speed of the printing press in the case that a variation of the operating speed according to the predetermined Speed function (23) while maintaining the second set value of the edit register. Method for cutting register control according to Claim 20, characterized in that a mathematical approximation function for a function (25) determined by measurements is used as the cutting register function (26). A method for cutting register control according to claim 21, characterized in that at least a part of the parameters of the approximation function (26) are stored in a memory so that they can be displayed and manually changed. A method for cutting register control according to any one of claims 19 to 22, characterized in that the speed function (23) is subdivided into various characteristic sections, which are associated with characteristic sections of the cutting register function (26). A cut-off control method according to claim 23, characterized in that the speed function (23) starts from a phase (A) of constant initial speed, successively increasing (B) the rate with constant rate of increase, a constant speed over a variable-length interval (C) but of predetermined minimum length, and having a decay rate (D) of constant rate, and terminating with a phase (E) of constant terminal velocity. A cut-off control method according to claim 24, characterized in that the cut register function (26) has a constant first value during the constant initial phase (A) of the speed function (23) to reach a constant second value during the constant phase (C) of higher speed , and that in the rising phase (B) of the velocity, it has a course which can contain a maximum exceeding the constant second value. A cut-off control method according to claim 24 or 25, characterized in that the cut-register function (26) has a constant first value during the constant initial phase (A) of the velocity function (23) to become a constant second during the constant phase (C) of higher velocity Value and during the constant final phase (E) reaches a constant third value and that it is approximately linear in the phase (D) of decreasing velocity. A method for cutting register control according to one of claims 19 to 26, characterized in that each cut-register setting provided adjustment of the printing machine is associated with an individual cut register function (26). A method for cutting register control according to one of claims 19 to 27, characterized in that the second set value of the cut register is the basis for the calculation of the first set value.

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