EP2496417B1 - Method for controlling a control variable for a processing machine - Google Patents

Abstract

A method is disclosed for controlling a control variable for a processing machine, which has driven rollers for transporting and/or for processing a material web, of which rollers at least one is not part of a clamping point. A first control element is pilot-operated based on a second control member according to a control value in order to adjust the at least one driven roller that is not part of a clamping point.

Description

The present invention relates to a method for controlling a controlled variable in a printing machine and to a computing unit for carrying out the method.

The invention is in printing machines, such as e.g. Newspaper printing machines, commercial printing machines, gravure printing machines, inline flexographic printing machines, packaging printing machines or securities printing machines, and in processing machines, such as e.g. Pouch machines, envelope machines or packaging machines, can be used. The web can be made of paper, cloth cardboard, plastic, metal, rubber, in foil form, etc.

State of the art

In processing machines, in particular printing machines, a web is moved along driven and non-driven rollers. The web is simultaneously processed by means of mostly driven processing equipment, For example, printed, punched, cut, folded, etc. In a processing machine, one or more processing registers (for example, longitudinal registers, page registers) and / or the web tension are usually regulated in the prior art.

A driven roller may belong to a nip, which positively or non-positively clamps the web and therefore can impress a web tension in the web. In a printing press, a nip, for example, from a printing unit, in which a frictional unit between the driven pressure cylinder, the impression roller and the material web is formed formed.

The web can be divided into web tension sections, wherein a web tension section is limited by two nips. Within a web tension section further driven and / or non-driven rollers may be arranged. Often the entire web is divided into several web tension sections, sometimes with different web tension setpoints. To maintain the setpoints usually a web tension control is used.

In the prior art, it is customary to set the register of a processing unit and / or the web tension of a web tension section by appropriate actuation of actuators, such as pressure cylinders or their drives, transport rollers or their drives, compensators and the like. Due to the coupling of the individual actuators to one another via the material web, such settings continue to propagate as disturbances and must be compensated at subsequent processing units and / or web tension sections by the associated controllers. In the prior art possibilities are described to decouple such settings, ie to leave the register of other processing plants or the web tension of other web tension sections unaffected during an adjustment.

In the DE 103 35 885 A1 a combined register and web tension control is disclosed. To decouple the register of web tension adjustment operations, an upstream strategy for web tension control is proposed.

In the DE 10 2007 017 096 A1 is described, in a downstream control by means of a (dynamic) downstream feedforward control all subsequent terminal points so that they directly compensate for the effects of the leading terminal point. As a result, it is ensured that all subsequent register controllers do not have to compensate for the disturbances of the coupling through the material web.

In the not pre-published DE 10 2008 056 132 a decoupling for an upstream control is proposed, wherein in addition to a (constant) upstream feedforward control also a (dynamic) downstream feedforward control is performed by means of PT1 element.

Next will be on the DE 10 2006 047 846 A1 directed.

However, the previous decoupling methods do not allow equally good results for all structural conditions. In particular, processing machines with driven rollers, which do not form a nip, are not sufficiently considered.

It is therefore desirable to provide an improved control method for printing machines with driven rollers which do not form a nip.

Disclosure of the invention

According to a method for controlling a controlled variable in a printing press with the features of claim 1 and a Arithmetic unit proposed for performing this method. Advantageous embodiments are the subject of the dependent claims and the following description.

Advantages of the invention

In addition to the previously mentioned processing and transport rollers, there are also other - typically massive - rollers with their own drives in processing machines. For example, is from the DE 10 2006 047 846 A1 also known to drive cooling and / or guide rollers to improve the register accuracy. Since these other rolls neither form nipples nor perform a register-based processing of the material, they are not taken into account in known decoupling strategies. However, it has been recognized that these rollers still adversely affect the decoupling. It has been shown that inclusion of these rollers in the decoupling strategy, for example by a precontrol depending on the decisive control value, leads to a significant improvement of the decoupling. The integration is expediently carried out in the known strategies (upstream or downstream, if appropriate in combination with stand color or predecessor color control). The pilot control is expediently carried out in the regulation of a processing register and / or a web tension. The driven roller is pre-controlled as a first actuator in response to the adjustment (decisive control value) of a second actuator.

In an embodiment, the pilot control takes place during the acceleration phase, for example, the startup of the machine. Friction occurs between the processing roll and the driven roll, typically through other non-driven rolls such as guide rolls. This friction leads to a stationary control deviation. Furthermore, the non-driven rollers have a moment of inertia, which must be overcome in speed changes. This leads to a dynamic deviation. In order not to allow these influences to be compensated for only after the occurrence of the control deviation by the controller, the at least one driven roller can be appropriately pre-controlled in the event of a speed change.

The feedforward control can be based-and / or adaptively-in particular on a speed change model. Model-based means that physical quantities, e.g. Web speed, format, modulus, inertias, friction, acceleration, etc., the corresponding pilot size is calculated. Adaptive means that the pre-control quantity is optimized after each acceleration phase. In particular, a learning algorithm is suitable for this, which observes the pilot control variable (eg the manipulated variable to the drive of the roller) during a speed change on the basis of a still occurring control deviation, and thus automatically to changing production conditions (eg change in ambient temperature, humidity, dryer temperature, etc.). ) adapts.

Appropriately, a slip and / or expansion slip is taken into account in the precontrol. Since the rollers are not part of a nip and they are wrapped only by the web, at high speeds an air film between roller and web can form and reduce the detention zone as a result. This can lead to a feedforward control of the roller no longer completely affecting the material web. It thus no longer comes to a complete decoupling of the adjustment because no complete power transmission from the cooling roller to the web takes place more. Advantageously, the sliding slip that occurs is correspondingly taken into account in the pilot control, so that, for example, as the transmission of power decreases, the precontrol is increased.

In an embodiment, the at least one driven roller is controlled and at least a third actuator in response to the control value for the first actuator piloted. If the driven roller itself is integrated in a control system, separate control values are generated for this roller, which in turn-correspondingly processed by a decoupling network-are used for the precontrol of other actuators in order to improve the decoupling.

An arithmetic unit according to the invention, e.g. a control unit of a printing press, is, in particular programmatically, adapted to perform a method according to the invention.

Also, the implementation of the invention in the form of software is advantageous because this allows very low cost, especially if an executing processing unit is still used for other tasks and therefore already exists. Suitable data carriers for providing the computer program are, in particular, floppy disks, hard disks, flash memories, EEPROMs, CD-ROMs, DVDs and the like. It is also possible to download a program via computer networks (Internet, intranet, etc.).

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

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

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

figure description

FIG. 1

shows a schematic representation of a trained as a printing machine processing machine with self-propelled cooling rollers.

FIG. 2

shows a schematic representation of an example of a control strategy according to the invention for a printing press according to FIG. 1 ,

In FIG. 1 is a trained as a printing machine processing machine, as can be based on the present invention, shown schematically and designated 100 in total. A printing material, for example paper 101, is fed to the machine via a feed unit 110. The paper 101 is guided and printed by processing units designed as printing units 111, 112, 113, 114 and reissued by a pull-out unit 115. The input, extraction and printing units 110 to 115 are positionable, in particular cylinder or angle correctable arranged. The printing units 111 to 114 are located in a web-tension-controlled area between the intake unit 110 and the extension unit 115.

The printing units 111 to 114 each have a printing cylinder 111 'to 114', against which a respective impression roller 111 "to 114" is made with strong pressure. The impression cylinders 111 'to 114' are driven individually and independently. The associated drives 11 "'to 114"' are shown schematically. The impression rollers 111 "to 114" are freely rotatable. The pull-in and pull-out units 110 and 115 each have two counter-rotating cylinders which guide the paper 101. Also ever a transport roller of the intake and the extension mechanism is individually driven by a drive 110 "'and 115"'. The feed and withdrawal unit 110, 115 and the printing units 111 to 114 each form a nip.

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

Often located between the printing units 111 to 114 and the respective cooling rollers each have a dryer which dries the printed on the web 101 color. The web 101 is passed over cooling rollers after a printing and optionally drying step. For this purpose, in the web section between the first printing unit 111 and the second printing unit 112, a cooling roller 121, in the section between the second printing unit 112 and the third printing unit 113, a cooling roller 122, in the section between the third printing unit 113 and the fourth printing unit 114, a cooling roller 123 and in the section between the fourth printing unit 114 and the extension unit 115, a fourth cooling roller 124 is arranged. According to the illustrated embodiment of the printing machine, all the cooling rollers 121 to 124 are self-propelled and equipped with their own drives 121 '' to 124 ''. In other types of machines or printing applications, for example, the driven rollers 121 to 124 may also have temperature-increasing (heating rollers) or other functions.

Based FIG. 2 describes how the self-propelled cooling rollers are included in a web tension and / or register control in the illustrated printing machine. It will be understood that the manner described is also valid for other self-propelled rollers. In FIG. 2 is a downstream control strategy with decoupling the example of the printing machine according to FIG. 1 described, however, in FIG. 2 only the elements essential to the example are shown. Downstream means that adjustments are made in web direction. If an actuator i (for example, a pressure cylinder) to be adjusted, the actuator i is adjusted itself. Upstream means that an adjustment is made against the direction of web travel. If the actuator i is to be adjusted, all the actuators in front of it (usually including the feeder) 1, 2,..., I-1 are adjusted, but the actuator i is left unchanged. It is known, for decoupling reasons in both strategies, to also adjust all subsequent actuators i + 1, i + 2,..., N.

In a controller (not shown), manipulated variables (controller output variables) uR1, uR2, uR3 and uR4 for the drives 111 "'to 114"' of the printing units 111 to 114 are determined. The manipulated variables can be used to regulate the web tension, for example, rotational speeds, fine adjustments and the like. act. In the regulation of the register, the manipulated variable is, for example, an angular offset and the like. The manipulated variables are processed by a decoupling network 200 and provided to the drives as modified manipulated variables a1, u2, u3 and u4. The decoupling network 200 includes control elements 201-203 and 211-213. Furthermore, the decoupling network 200 provides manipulated variables uV1, uV2, uV3 for the drives of the cooling rollers.

The control elements 201-203 serve for the downstream decoupling of the printing units from an adjusting movement. The control elements 211-213 are used for downstream decoupling of the driven cooling rollers and cause a pilot control in response to a manipulated variable. The actual configuration of the precontrol is generally dependent on the control strategy (predecessor color or reference color) and the adjustment direction (downstream or upstream). The control elements 211-213 represent corresponding dynamic decoupling strategies. For example, a feedforward control can take place in a downstream predecessor color control via a combination of a DT1 element and a dead time. The time constants of the control elements are Depending on the material web length, here on the one hand from printing unit to cooling roller and on the other hand from the cooling roller to printing unit, and the web speed. For example, in an adjustment of the drive 111 '' based on a manipulated variable uR1 this unchanged to the drive and additionally via the control member 211, which takes into account the web length between roller 111 'and roller 121, and the control member 201, the web length between roller 121 and roller 112 'taken into account, precontrolled to the following actuators, wherein the pilot control variable and the manipulated variables uV1, u2, uV2, u3, uV3, u4 received.

In the present example, the cooling rollers are not regulated, so no manipulated variables (controller outputs) are provided for the cooling rollers. Optionally, the cooling rollers could also be controlled in addition to the pilot control. The associated manipulated variable for a chill roll would expediently decoupled in this case as well as the manipulated variables for the printing cylinder dynamically. The decoupling is expediently carried out by means of dynamic timers. These may be, for example, PT1, PT2, PTn, DT1, DT2, DTn links, dead times, etc. Furthermore, non-linear precontrol systems, which have similar characteristics as the dynamic timers, are also permissible.

Claims (10)

1. Method for controlling a control variable for a printing press (100) having a plurality of printing units, in particular a gravure printing press, which has rolls (111', 112', 113', 114', 121, 122, 123, 124) which are driven for transporting and/or for processing a material web (101) and of which at least one (121, 122, 123, 124) is not a constituent part of a clamping point (110, 111, 112, 113, 114, 115), and is arranged between a first clamping point (111, 112, 113, 114) and a second clamping point (112, 113, 114, 115), which is formed in each case from a driven impression cylinder and a freely rotatable impression roller or from two transport rolls, of which one is driven, a first actuator (121''', 122''', 123''', 124''') being pilot-controlled for adjusting the at least one driven roll (121, 122, 123, 124) which is not a constituent part of a clamping point (110, 111, 112, 113, 114, 115), as a function of an actuating value (uR1, uR2, uR3, uR4) with respect to a second actuator (111"', 112"', 113"', 114"') for adjusting a driven roll (111', 112', 113', 114') which is a constituent part of the first clamping point (111, 112, 113, 114), and as a function of a web length between the driven roll (111', 112', 113', 114') which is a constituent part of the first clamping point (111, 112, 113, 114) and the at least one driven roll (121, 122, 123, 124) which is not a constituent part of a clamping point (110, 111, 112, 113, 114, 115), and characterized in that a third actuator (112"', 113"', 114"', 115"') is pilot-controlled for adjusting a driven roll (112', 113', 114') which is a constituent part of the second clamping point (112, 113, 114, 115), as a function of the actuating value (uR1, uR2, uR3, uR4) with respect to the second actuator (111"', 112"', 113"', 114"') and as a function of a web length between the driven roll (111', 112', 113', 114') which is not a constituent part of a clamping point (110, 111, 112,' 113, 114, 115) and the at least one driven roll (121, 122, 123, 124) which is a constituent part of the second clamping point (112, 113, 114, 115).
2. Method according to Claim 1, the at least one driven roll being configured as a cooling/heating roll (121, 122, 123, 124) or guide roll.
3. Method according to Claim 1 or 2, a processing, transport, cooling, heating and/or guide roll or their/its drive (111"', 11"', 113"', 114''') serving as second actuator.
4. Method according to one of the preceding claims, a compensator serving as second actuator.
5. Method according to one of the preceding claims, the control variable being a processing register and/or a web tension.
6. Method according to one of the preceding claims, the pilot control taking place in a model-based manner, by the corresponding pilot control variable being calculated from physical variables, such as material web speed, format, modulus of elasticity, inertia, friction, acceleration, and/or in an adaptive manner, by the pilot control variable being optimized after each acceleration phase.
7. Method according to one of the preceding claims, a sliding slippage and/or expansion slippage of the at least one driven roll (121, 122, 123, 124) being taken into consideration in the pilot control.
8. Method according to one of the preceding claims, the pilot control taking place in a steady-state and/or dynamic manner for different speed states.
9. Method according to one of the preceding claims, the at least one driven roll being controlled.
10. Computing unit which is set up for carrying out a method according to one of the preceding claims.

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