EP1726548A1 - Method and device for controlling the tension in a running web in a web processing device and device for processing a running web - Google Patents

Abstract

Method for controlling the tension of a web (08) in a web-processing device (01) comprises controlling the tension of the web between a traction mechanism (04) and a holder (14) whilst periodically varying a parameter representing the web tension and changing the transport speed of the traction mechanism and holder so that the parameter of the periodic variation decreases. An independent claim is also included for a device for controlling the tension of a web in a web-processing device. Preferred Features: The transport speeds are changed relative to each other when the parameter of the periodic variation of its amplitude exceeds a determined limiting value.

Description

The invention relates to methods and apparatus for controlling web tension of a traveling web in a web processing apparatus and apparatus for processing a traveling web according to the preamble of claim 1, 6, 16 or 17.

Is in such devices, the web tension in front of the holding means, in particular between feeder and holding means, too high, so there is a risk that the material web tears on the holding means or, even worse, that the web even tears off. If the material web breaks free on the holding means, then it is damaged at least at those points where the holding means grip the material web. On the other hand, if the material web tears off, this leads to stoppages in the device, for the elimination of which a great deal of time must be expended, which in turn leads to production losses and financial expenditures. On the other hand, if the web tension is too low, there is a risk of congestion of the material web in the device, which also leads to a pusher. In order to avoid tampers or breaks or tears of the material web, the same amount of material per unit time of the device must be supplied on average as are dissipated by it.

From the DE 41 37 818 A1 a device is known in which the web tension between the feeder and the holding means can be regulated. In this device, the feeder is designed as a pair of draw rollers, wherein the regulation of the web tension is achieved by adjusting the rotational speed of the draw rollers. In the cited document, however, it is not disclosed according to which criteria the regulation is directed. Neither is one Optimum value for the web tension indicated or which distinguishes such, nor can the font be removed, by which a deviation of the web tension is detected by the optimum or desired value.

The basic requirement for regulating the web tension to a target value is that the actual value of the web tension can be measured accurately and with time resolution. The detection of the actual value of the web tension is technically quite difficult to perform. Known devices for detecting the web tension such as web tension measuring rollers or web tension sensors determine the actual value of the web tension usually indirectly over the elongation of the web or phase differences between the feeder and the holding means. For example, in the EP 0 951 993 A1 followed such a path to control the web tension. Indirect detection of the actual value of the web tension, however, is associated with relatively large inaccuracies. The uncertain knowledge of the actual web tension in turn has an unfavorable effect on the regulation of the web tension, since the exact knowledge of the actual value of the web tension is indispensable for achieving an exact and reliable control.

The DE 42 38 387 A1 discloses a method for cutting register control in a plano boom of a rotary printing machine with a feeder, a separating device and a conveying roller. The feeder and the feed roller are each controlled by independent control circuits with respect to an angular position of an upstream printing unit. The control is carried out in each case to be maintained relative to the printing unit angular positions, wherein in case of deviation of the actual from the target angular position in an inner loop, the power supply of the respective drive is controlled.

The DE 37 35 303 C2 shows a folder with a feeder, a separating device and a point needles folding blade cylinder.

The DD 33 320 discloses a folder with a jaw-type jaw cylinder.

It is an object of the invention to provide methods and apparatus for controlling web tension of a traveling web in a web processing apparatus and apparatus for processing a running web.

The object is achieved by the invention by the features of claim 1, 6, 16 or 17.

With the invention can be - without the actual value of the web tension would have to be detected - the web tension before the cutting point, especially between feeder and cutting point, during operation of the device quickly and reliably set to zero or a value close to zero. This ensures that the material web is pulled smooth after gripping and before cutting, without the risk of Ausoder tearing off the material web.

Instead of the amount of any size representative of the web tension, according to the invention a periodic variation of such a size is used to control the web tension. In general, the variation of such a quantity is not representative of the web tension in the sense that a web tension could be uniquely calculated from a measurement of this variation. However, the special case of vanishing (or almost vanishing) web tension in the present case is reliably recognizable by the fact that also variations in the web tension, which are due to periodic processes in the cutting device, such as the cutting of the web itself or the gripping of the tail, tend to disappear. The decision as to whether a measurand varies or not is generally much easier and more reliable to make than whether a measurand is a given given Has value.

If the periodic variations of any quantity representative of the web tension exceed a limit, it can be concluded that the web tension is too great. In order to lower the web tension, therefore, the average drive power delivered by the drive to the feeder is increased, so that the web of material is retracted by the feeder faster. If the web retracted faster, the web tension between feeder and holding means is reduced. However, this also reduces the periodic variations of the variable representative of web tension. If the periodic variations fall below the limit again or if they disappear, the desired web tension is reached again and the drive power can be kept constant again.

Reliability and sensitivity are particularly good when only those periodic variations in web tension are taken into account whose period coincides with that of cutting the web. Voltage fluctuations due to other causes or disturbances are thus ignored.

If the fluctuation of the web tension and thus the web tension itself is controlled exactly to zero, it is not possible to detect whether the web may be fed into the device faster than it is spent and runs the risk of causing a blockage. This risk is excluded if the fluctuation of the web tension is assumed to be a small but displaceable limit value.

Because variations in web tension affect the average power delivered by the motor to a tension member, particularly the neck, such that this power also varies accordingly, the size representative of the web tension can be chosen to be that representative of the power output by the engine is. Such sizes are particularly easy and without further record additional device measures. In this case, the quantity representative of the power output by the engine is very particularly preferably the current strength of the operating current absorbed by the motor.

The device may, for example, have a display on which control measures and / or effects of the control are displayed. This also allows operators of the device to monitor the operation of the device.

Due to the simple design, the feeder is preferably a pair of draw rollers.

The holding means is preferably on a transport cylinder of a folder, z. B. designed as a collection cylinder arranged. The holding means may be, for example, a gripper or a jaw or a spur strip with puncture needles. If the holding means is arranged on a collecting cylinder, the device moreover preferably comprises a cutting cylinder cooperating with the collecting cylinder at the cutting point. In such a device, both the collecting cylinder and the cutting cylinder are rotatably mounted. The drawn-in material web is taken between the intake and cutting point of the holding means, taken along rotation of the collecting cylinder, wherein the holding means passes through the cutting point, and then cut at the now located between intake and holding means cutting point cooperating with the collecting cylinder cutting cylinder. The material section thus obtained is still held by the holding means. He is further promoted by the rotating cylinder collector and later derived from known facilities either immediately from the collecting cylinder or only after a predetermined number of revolutions of the collecting cylinder. In this case, with each revolution of the collecting cylinder, a new material section on the already on the collecting cylinder resting material portion placed to form a stack with a predetermined number of sections of material, so that finally this stack is derived from the collecting cylinder.

Most preferably, the device is a folder of a printing press, in particular a web-fed rotary printing press.

Embodiments of the invention are illustrated in the drawings and will be described in more detail below.

Fig.1:

schematischer Aufbau eines Teils einer Druckmaschine mit einem Falzapparat;

Fig. 2

eine zweite, schematische Ausführung mit mehreren Falztrichtern und Zugelementen.

Show it:

Fig.1:

schematic construction of a part of a printing press with a folding apparatus;

Fig. 2

a second, schematic design with multiple formers and tension elements.

To the device 01 shown in Figure 1, in particular folding device 01 include a transport cylinder 02, in particular designed as a collecting cylinder 02, a cutting cylinder 03, a tension element 04), z. B. a feeder 04, in particular a pull roller pair 04, a motor 06, a control unit 07 and a display 18, for. B. a screen 18. On collecting cylinder 02 holding means 14, in particular Punkturleisten 14 are arranged with puncturing needles. The collecting cylinder 02 and the cutting cylinder 03 are set against each other and define a cutting gap 16 and cutting point 16, in the following also gap 16. Both the collecting cylinder 02 and the cutting cylinder 03 are rotatably mounted. They rotate in the direction indicated by an arrow. The Zugwalzenpaar 04 is driven by the engine 06, in turn, by the control unit 07 is controlled. With the control unit 07, a screen 18 may be connected, to which the control unit 07 can output data. Preceding the folder 01 are in the printing press a roller 09, z. B. a funnel inlet roller 09 with a hired to this roller 11, z. B. a pressure roller 11 or pressure roller 11. Between the rollers 09; 11 and the folder 01, a former 12 is arranged.

A processed web 08, z. B. web 08, in particular paper web 08, wraps around the hopper inlet roller 09 and is kept pressed by the pressure roller 11 against the hopper inlet roller 09. It then passes through the former 12. In the former 12, the paper web 08 is folded longitudinally. The longitudinally folded paper web 08 runs after the former 12 in the folder 01 a. The term "paper web 08" or "longitudinally folded paper web 08" is representative of a strand of several successive paper webs 08 or longitudinally folded paper webs 08.

In the folder 01, the paper web 08 is pulled through the driven by the motor 06 Zugwalzenpaar 04. In this case, a drive power is delivered from the motor 06 to the Zugwalzenpaar 04, which exerts a pulling force and on the expiring from the Zugwalzenpaar 04 paper web 08 a thrust according to this drive power to the incoming paper train 08 in the Zugwalzenpaar 04. The higher the drive power delivered by the motor 06, the greater is the tensile force exerted by the draw roller pair 04 on the incoming paper web 08 and the thrust force exerted on the paper web 08 leaving the draw roller pair 04. The size of the output from the engine 06 drive power is controlled by the control unit 07.

The expiring from the Zugwalzenpaar 04 paper web 08 is - for example, not shown in the figure bands - pressed against the collecting cylinder 02 and impaled by out of the collecting cylinder 02 Punkturnadeln one of the spur strips 14. In this case, the paper web 08 between the spur strip 14 and the Pull roller pair 04 smooth pulled. The now held by the point needles free end of the paper web 08 then runs into the gap 16 formed by the collecting cylinder 02 and the employed him cutting cylinder 03 a. In the course of the further rotation of the collecting cylinder 02, the sprocket 14 passes through the gap 16 and pulls the paper web 08 with it through the gap 16. While the spur strip 14 moves through the gap 16 and beyond, the cutting cylinder rotates in the direction of the arrow 03 arranged cutting blade 17, the gap 16 and intersects in cooperation with the collecting cylinder 02 a material section 13, in particular paper section 13 of the paper web 08 from. Corresponding to the above with respect to a strand of a plurality of superimposed paper webs 08, material section 13 is also to be understood as the section of a multi-layer strand section. Thus, the gap 16 is a cutting point of the folder 01. Even before the paper section 13 is cut at the gap 16 of the paper web 08, already has the paper section 13 holding sprocket 14 on the collecting cylinder 02 subsequently arranged spur 14 the paper web 08 before Passing the gap 16 reached and pierced with their puncture needles, so that the paper web 08 is held not only before and during but also immediately after the success of the cut. The cut paper section 13 is finally derived in a known manner from the collecting cylinder 02. Since this is not the subject of the invention, in the present case a description of the derivation of the paper section 13 from the collecting cylinder 02 is dispensed with.

If the puncture strips 14 have due to the rotation of the collecting cylinder 02 with respect to the Zugwalzenpaar 04 an overrun, builds up within the punctured on one of the puncture strips 14 paper web 08 web tension between the Zugwalzenpaar 04 and this spur strip 14, causing it to an elongation of the paper web 08th comes. If the web tension is too great, this can lead to puncture tears at those parts of the paper web 08 where it is punctured by the puncturing needles. In the worst case, the paper web 08 rips over the Whole width from and the retraction 04 further retracted paper web 08 accumulates between feed 04 and collecting cylinder 02 and causes a stuffer in the folder 01. In order to avoid excessive growth of the web tension, the web tension in the paper web 08 is therefore between the Zugwalzenpaar 04 and regulated the paper web 08 holding spur 14, which will be explained below.

It is assumed that the web 08 between the Zugwalzenpaar 04 and the leading end of the paper web 08 holding sprocket 14 is under a non-vanishing voltage when inserting the web tension control. If the subsequent spur strip 14 pierces the paper web 08, it initially carries no tension. Only when cutting the paper section 13, the tension in the paper web 08 breaks for a short moment, and builds on the subsequent spur strip 14 again. In this phase of rapid stress build-up, the risk of breaking is particularly high. The short-term collapse of the web tension leads to the fact that the input to the paper web 08 in the folder 01 to be performed drive work is applied solely by the motor 06 of the Zugwalzenpaars 04. Its performance and thus its current consumption rise sharply for a short time. This process is repeated every time a paper section 13 is cut off from the tensioned paper web 08.

The operating current of the motor 06 is monitored by the control unit 07 for the occurrence of such periodic variations. Once such periodic variations of the operating current occur and exceed a certain limit, the control unit 07 concludes that the web tension in the paper web 08 between the Zugwalzenpaar 04 and the spur 14 is too large. In order to reduce the web tension, the control unit 07 controls the rotational speed of the motor 06 in such a way that the drive power or rotational speed output by the pulling roller pair 04 on the paper web 08 in the direction of pulling in increases. As a result, however, the overfeed of the puncture strips 14 with respect to the draw roller pair 04 is lowered, so that the paper web 08 is stretched less between the Punkturleisten 14 and the Zugwalzenpaar 04 and the web tension of the paper web 08 therefore less fails. With reduced web tension, the size of the periodic variations also decreases. Once these fall below the limit, the speed and / or drive power of the motor 06 is not further increased. It may be provided that the control unit 07 continuously outputs data on the periodic variations and the output from the engine 06 speed and / or drive power to the screen 18 on which these are displayed for information from the press operator.

In a preferred embodiment, the motor 06 or its drive controller (not shown) by a machine control set a target speed. At o. G. Procedure, this target speed is now superimposed on the machine speed by the method or the control unit 07 an offset, so that the periodic variations in o. G. Be reduced. The stepping up of the direction and total size of this offset can be done step-by-step in an iterative procedure.

Although said limit will generally be chosen so small that rupture of the paper web 08 is safely excluded, but still greater than 0 choose to ensure that the paper web 08 between the Zugwalzenpaar 04 and the collecting cylinder 02 remains taut.

If you select exactly zero as the limit, the case may occur that an overrun of the Zugwalzenpaars 04 cumulatively with respect to the collecting cylinder 02, with the result that paper between the Zugwalzenpaar 04 and the collecting cylinder 02 accumulates and leads to a pusher. To prevent this, it may be provided that the control unit 07, whenever a disappearing tension has been maintained for a predetermined period of time, slightly reduces the power of the motor 06. (Or in below mentioned second embodiment, the target speed or power for the drive of the transport cylinder 02 or of the folder 01 increases.) This leads to the fact that the feeder runs slower and possibly an existing overfeed is reduced. Once the overfeed has been removed, a non-zero tensile stress reoccurs, and the controller 07 again begins to control this tension to zero.

The procedure and device 01 has hitherto been explained with reference to a first embodiment, wherein the rotational speed or peripheral speed of the draw roller pair 04 or its motor 06 has been changed by the control unit 07.

It is essential, however, that by a suitable control device 07 or procedure, the transport speeds of retraction 04 and holding means 14 to each other are changed in such a way that the detected periodic variation of the representative of the web tension size (preferably engine power here) in o. Way is reduced.

This can also be done in a second embodiment, not shown, that the transport speed or speed at retraction 04 unchanged (or according to the setpoint specification) remains, while reducing the periodic variation, the transport speed of the holding means 14, d. H. the peripheral speed of the transport cylinder 02 is changed in the sense that the web tension between feed 04 and holding means 14 decreases - ie z. B. is slowed down. This happens, for example, by lowering the setpoint speed for the drive of the transport cylinder 02 or the folder 01.

The procedure and the device has been explained above, with reference to an advantageous embodiment, as the cutting gap 16 upstream and the former 12 traction element 04 of the retraction 04 of the folder 01 was used and taken into account.

In an alternative embodiment of the two o.g. Embodiments, a tension element 04 '(eg, tension roller 04') arranged in the strand path between the former 12 and the folder 01 is used instead of the intake 04 and taken into account in accordance with the above explanations. In the presence of a plurality of formers 12 and / or a plurality of tension elements 04 'can also be several draw rollers 04' used in or their motors 06 'and considered accordingly in the controller 07 (Figure 2).

In a third embodiment, both the feeder 04 and in addition one or more of the formers 12 downstream tension elements 04 'are used and regulated accordingly.

The procedure or the control unit 07 may be executed independently, or part of a train 08 elsewhere, z. B. in front of the hopper 12, in particular in front of a catchment work, respect. Its voltage regulating web tension control device.

LIST OF REFERENCE NUMBERS

01

Contraption; folding

02

Transport cylinder; collecting cylinder

03

cutting cylinder

04

feeder; tensile member; pair of drawing rollers

05

-

06

engine

07

control unit

08

Train; Web; paper web

09

Roller; Former inlet roller

10

-

11

Roller; pressure roller; pressure roller

12

formers

13

Material portion; paper section

14

Holding means; spur

15

-

16

Cutting gap; Cutting location; gap

17

cutting blade

18

Display; screen

04 '

feeder; tensile member; pair of drawing rollers

06 '

engine

Claims (30)

Method for regulating the web tension of a moving web (08) in a web-processing device (01), wherein on the web path between a former (12) and a cutting point (16) a tension element (04, 04 ') cooperating with the web (08) for conveying the web (08), and wherein the device (01) comprises at least one holding means (14) and the cutting point (16), the web (08) being formed by the pulling element (04; 04 ') with an adjustable first Transported transport speed and held by the holding means (14) and transported at a second transport speed, and at the cutting point (16) between the tension element (04; 04) and holding means (14) individual material sections (13) are cut off the web (08), and wherein the method controls the web tension of the web (08) between the tension member (04; 04 ') and the holding means (14) by periodic variations of a variable representative of web tension are detected; and - The transport speeds of tension element (04, 04 ') and holding means (14) are changed in relation to each other in such a way that the size of the detected periodic variation decreases. A method according to claim 1, characterized in that the change in the transport speeds to each other is made when the size of the detected periodic variations in amplitude exceed a certain threshold. A method according to claim 1, characterized in that the change in the transport speeds to each other by a change in a target speed on the tension element (04, 04 ') and / or of the holding means (14) having a transport cylinder (02). A method according to claim 2 and 3, characterized in that the target speed of the tension element (04, 04 ') is increased when the size of the periodic variations exceed the limit. A method according to claim 2 and 3, characterized in that the target speed of the holding means (14) having a transport cylinder (02) is reduced when the size of the periodic variations exceed the limit. Method for regulating the web tension of a moving web (08) in a web-processing device (01), wherein on the web path between a former (12) and a cutting point (16) a tension element (04, 04 ') cooperating with the web (08) for applying a controllable driving force to the web (08), and wherein the device (01) comprises at least one holding means (14) and a cutting point (16), the web (08) being held by the pulling element (04; 04 ') is pulled in and held by the holding means (14), and at the cutting point (16) between the tension element (04, 04 ') and holding means (14) individual material sections (13) are cut off from the web (08), and wherein with the method Web tension of the web (08) between the tension element (04, 04 ') and the holding means (14) is controlled by periodic variations of a variable representative of web tension are detected; and the driving force exerted by the tension element (04, 04 ') is increased when these detected periodic variations in the quantity representing the web tension exceed a certain limit in their amplitude. A method according to claim 6, characterized in that the driving force is increased by a target rotational speed of the tension element (04, 04 ') is increased. A method according to claim 1 or 6, characterized in that in step (a) only those variations are detected and / or taken into account, whose period coincides with that of the cutting of the material sections. A method according to claim 2 or 6, characterized in that the limit value is different from zero. Method according to one of the preceding claims, characterized in that the tension element (04; 04 ') is driven by a motor (06), wherein the variable representative of the web tension is a quantity representative of the power output by the motor (06). Method according to claim 1 or 6, characterized in that a transport cylinder (02) having the holding means (14) is driven directly or indirectly by a motor, the quantity representative of the web tension being a quantity representative of the power delivered by that motor. Method according to claim 10 or 11, characterized in that the quantity representative of the power output by the motor (06) is the current strength of the operating current received by the motor (06). Method according to one of the preceding claims, characterized in that control measures and / or effects of the control are displayed on a display (18). Method according to one or more of the preceding claims, characterized in that a drawing roller (04) of a draw-in (04) of the device (01) is taken into account as the pulling element (04). Device according to one or more of the preceding claims, characterized in that a tensioning roller (04 ') arranged in the strand path between the former (12) and the entry into the device (01) is taken into consideration as the tension element (04). Device (01) for regulating the web tension of a moving web (08) in a web-processing device (01), wherein on the web path between a former (12) and a cutting point (16) a tension element (04; 04 ') for conveying the web (08) is arranged, and wherein the device (01) at least one holding means (14) and the cutting point (16), wherein the tension element (04, 04') the web (08) with a transported adjustable first transport speed and the holding means (14) holds the retracted web (08) and transported at a second transport speed to at the cutting point (16) between the tension element (04, 04 ') and holding means (14) individual material sections (13) to cut off the web (08), characterized in that the device (01) comprises a control unit (07) which is set up to change the transport speeds of the tension element (04; 04 ') and holding means (14) in relation to one another that the magnitude of the detected periodic variation decreases. Device (01) for processing a moving web (08), in particular a device (01) for carrying out a method according to one of the preceding claims, comprising a tension element (04; 04 ') for exerting a driving force on the web (08), at least a holding means (14) and a cutting point (16), wherein the pulling element (04; 04 ') retracts the web (08) and the holding means (14) holds the drawn web (08) to intercept at the cutting point (16) Pull element (04, 04) and holding means (14) individual material sections (13) from the web (08), characterized in that the device (01) a A control unit (07) adapted to increase the driving force exerted by the tension member (04) when periodic variations of a magnitude representative of the web tension exceed a limit. Device (01) according to claim 16 or 17, characterized in that the control unit (07) is arranged to take into account only those periodic variations whose period coincides with that of the cutting of the web (08). Device (01) according to claim 16 or 17, characterized in that the feeder (04) by a motor (06) is driven, wherein the representative of the web tension size is representative of the output from the motor (06) power size. Device (01) according to Claim 16 or 17, characterized in that a transport cylinder (02) having the holding means (14) is driven directly or indirectly by a motor, the quantity representative of the web tension being representative of the power delivered by that motor Size is. Device (01) according to claim 19 or 20, characterized in that the representative of the power output from the motor (06) power is the current strength of the motor (06) recorded operating current. Device (01) according to one of claims 16 to 21, characterized in that a display (18) is arranged for displaying control measures and / or effects of the control. Device (01) according to one of claims 16 to 22, characterized in that the tension element (04) is formed by a pair of draw rollers (04). Device (01) according to one of claims 16 to 23, characterized in that the holding means (14) is arranged on a collecting cylinder (02). Device (01) according to claim 24, characterized in that the holding means (14) is a gripper or a jaw or a spur strip (14). Device (01) according to one of claims 24 or 25, characterized in that a cutting cylinder (03) cooperating with the collecting cylinder (02) is arranged at the cutting point (16). Apparatus (01) according to any one of claims 16 to 26, characterized in that the device (01) is a folding apparatus (01) of a printing press. Device (01) according to claim 16 or 17, characterized in that the control unit (07) is part of a web tension control device, which regulates the web tension in at least one of the former (12) located portion of its path. Device (01) according to claim 14 to 28, characterized in that the tension element (04) as a feeder (04) of the device (01) is formed. Device (01) according to claim 14 to 28, characterized in that the tension element (04 ') is designed as a tension roller in the strand path between the former (12) and the entry into the device (01).

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