EP1945847B1 - Method for setting the linear force in the working gap of a pair of rollers and device for treating a web of material - Google Patents

Abstract

In a method for setting the linear force in the working gap of a pair of rollers which comprises at least one roller that can be hydraulically controlled in terms of its deflection and a pneumatically actuated device for adjusting the rollers, in which method the setting of the linear force is performed by presetting a pneumatic actuating pressure and adapting the hydraulic pressure in the sense of minimizing the linear force error, the hydraulic pressure values that are assigned to the pneumatic pressure values for the entire working spectrum of the pair of rollers (3) are stored in a data memory (15) and are used for activating at least one electro-pneumatic proportional valve (19, 19') to actuate the device for adjusting the rollers (1, 2) and for activating a hydraulic source (34) providing the hydraulic actuating pressure for the at least one roller that can be controlled in terms of its deflection.

Description

The invention relates to a method for adjusting the line force in the working nip of a pair of rollers comprising at least one hydraulically deflectable roller and a pneumatically actuated device for adjusting the rollers, wherein the adjustment of the line force by specifying a pneumatic actuating pressure and adjustment of the hydraulic pressure in the sense of Minimization of line force error takes place, as well as a device for the treatment of a web, with a nip forming roller pair, of which at least one roller is designed as a hydraulically deflectable roller, and with a pneumatically actuatable device for adjusting the rollers, wherein the adjustment of the line force in the Working gap by specifying a pneumatic actuation pressure and adjustment of the hydraulic pressure in the sense of minimizing the line force error takes place.

Such a method and such a device are from the document US-A-4,392,288 known.

Such a device can also serve, for example, for the wet treatment of a web and is in the form of a padder for example from the EP-A-1 256 650 known. This comprises a trough, in which a web is introduced from a deflection roller coming from top to bottom, whereupon a deflection roller at the bottom of the trough and vertically upwards out of the trough is led out, after passing a arranged above the trough spreader roller pair of rollers to pass through, the working gap is used to squeeze off excess treatment liquid.

In this pair of rollers, one of the two rollers is arranged to be displaceable in the machine frame of the device in the sense of opening and closing the working gap. To close the working gap, a pneumatically actuated device is provided, wherein the pressure required for the particular application squish pressure is set by specifying the pneumatic actuation pressure.

In order to achieve a uniform squeezing result over the web width, it is necessary to correct a line force error caused by a bending of the rolls. As is known, for this purpose at least one of the two rollers is designed as a hydraulically deflectable roller in which a rotating roller shell is hydraulically supported on a crosshead passing through the roller shell. Formed by the force acting on the rollers in the nip reaction forces a so-called "fish belly profile" in which the gap width in the axial direction of the rollers seen in the central region is greater than at the edges, this fish belly profile can be at least partially compensated by the at least a hydraulic deflection-controllable roll is acted upon by a hydraulic pressure at a height which leads to a deflection correction of the roll shell in the sense of a substantially constant nip and thus over the entire width of the web substantially constant squeezing action.

Since the required for the linear force correction hydraulic pressure significantly depends on the predetermined by the pneumatic pressure level of the line force, it is known to use pneumatic / hydraulic ratio controller, which in function of the rollers and thus the height of the line force substantially determining pneumatic pressure controlling the hydraulic pressure with which the at least one deflection-controllable roller is acted upon.

Such a configured, belonging to the prior art device is - schematically - in Fig. 2 shown.

A disadvantage of such a device, that the working areas of the pneumatic / hydraulic ratio controller are limited, so that the device can not be operated in the entire line force range, which would be covered with the work gap limiting rollers.

The invention is therefore based on the object, a method for adjusting the line force in the working gap of a pair of rollers or a device for Treatment of a web, in particular for the wet treatment of a web of the type mentioned, which allows the treatment of webs in a larger line force range in a nip formed between two rollers.

This object is achieved by the method given in claim 1.

Characterized in that in a data store the pneumatic pressures associated with the hydraulic pressure for the entire working spectrum of the roller pair are stored, and that this data for driving at least one electro-pneumatic proportional valve for actuating the device for adjusting the rollers and for driving a hydraulic actuating pressure for the at least one deflection-controllable roller can be used, can be dispensed with the pneumatically / hydraulically acting ratio controller. The line printing area in which the web treatment can take place is thus limited only by the rollers delimiting the nip. In addition, by selecting the function according to which the hydraulic pressures are assigned to the given pneumatic pressures, a correction of the line force errors substantially improved over the prior art can be achieved.

Basically, it is possible by means of the corresponding data on the one hand electro-pneumatic proportional valves for actuating the device for adjusting the rollers, which includes, for example, pneumatically actuated piston / cylinder units or inflatable bellows, on the other hand, an electro-hydraulic proportional valve for controlling the actuating pressure for the at least one to steer deflection-controllable roller.

However, it has been found that for controlling a device influencing the hydraulic pressure, such a device is particularly well suited, which is actuated pneumatically on the primary side. Accordingly, preferably by means of the data for the hydraulic pressures, an electro-pneumatic proportional valve is actuated and by means of the resulting pneumatic pressure the pneumatically actuated, the hydraulic pressure influencing device driven.

It is then particularly preferred to design the device as a pneumatic hydraulic overflow valve.

In order to further improve the quality of the line force correction, it is preferable to measure the pneumatic and hydraulic pressures and to use the measured values for comparison setpoint / actual value.

These can then - as is particularly preferred - be supplied to a control device which influences the pneumatic and hydraulic pressures in the sense of minimizing the difference between the desired and actual values. This can be done constructively by supplying the difference values to an electronic device which corrects the data taken from the data memory by the detected difference value.

The reproduced in claim 6, inventive device for the treatment of a web thus comprises a data memory, in which the pneumatic pressures associated hydraulic pressures for the entire working spectrum of the roller pair are stored. The data memory is provided in a programmable logic controller which includes signal outputs to which electrical signals correlating with the pneumatic and hydraulic pressures are applied, the signal outputs being operatively connected to the pneumatic or hydraulic pressure influencing devices.

The devices influencing the pneumatic pressure preferably comprise an electro-pneumatically acting proportional valve.

The device which influences the hydraulic pressure also comprises, particularly preferably, an electro-pneumatically acting proportional valve which, on the pneumatic side, has a device for influencing the hydraulic pressure Pressure is operatively connected, which may be formed, for example, as pneumatically actuated, hydraulic overflow valve.

It is particularly preferred if the device comprises pneumatically / electrically or hydraulically / electrically acting measuring devices for detecting the pneumatic and hydraulic actuation pressures, since the values detected by means of these measuring devices can then be used to correct the signals specifying the pneumatic or hydraulic pressures , whereby a regulation of these prints in the strict sense is possible.

The invention will now be described with reference to the accompanying drawing, the schematic block diagrams of the invention ( Fig. 1 ) and a device belonging to the prior art ( Fig. 2 ), will be explained further.

A device according to the invention comprises a nip roller pair 3 formed from an upper roller 1 and a lower roller 2, the rollers 1, 2 forming between them a working gap through which a web of material is guided in the engaged state of the two rollers 1, 2.

The rolls are designed as hydraulically deflection-controllable rolls of known design comprising a roll shell 4, 5 rotatably mounted on a crosshead, which can be acted upon by means of hydraulically acting means in the direction of the working gap 6 from the inside with a hydraulic force.

In the in Fig. 1 In the embodiment shown, the rollers are designed as so-called S-rollers, in which the area facing the nip within the roller shell and the area facing away from the nip can be subjected to hydraulic pressures of different levels. For this purpose, the rollers 1, 2 supply lines 7, 8 for pressurized hydraulic fluid, which are connected to the working gap 6 toward acting, not shown in the drawing pressure chambers.

The hydraulic fluid is supplied via throttles 9, 10 each acting in an opposite direction pressure chamber, so that the roll shells 4, 5 are stored under a resulting, working gap 6 toward acting force on the respectively associated crosshead floating. The hydraulic fluid is discharged after passing through the rollers 1, 2 via leads 11, 12.

The lower roller 2 is mounted to open and close the working gap 2 displaceable in a machine frame, not shown in the drawing. On the two ends of their crosshead acts in each case a pneumatically actuated bellows 13, 14, as in Fig. 1 is indicated by the line L. If the bellows 13, 14 acted upon with compressed air, the lower roller 2 is made against the upper roller 1, with a line force, which is dependent on the level of pneumatic pressure, with which the bellows 13, 14 are acted upon.

The greater the pressure in the bellows 13, 14 and thus the line force in the working gap 6, the stronger the tendency of the roll shells 4, 5, relative to their axial direction in the center region in the sense of an enlargement of the working gap 6 durchzubiegen. To counteract this tendency, the roller shells 4, 5 are applied in the working gap 6 facing areas from the inside with hydraulic pressure, the height must increase, the higher the pneumatic contact pressure.

In order to automatically carry out this increase in the hydraulic pressure as a function of the pneumatic setting pressure over at least the entire working range of the rollers 4, 5, the device according to the invention has a data memory 15 designed as a programmable logic controller in which the hydraulic pressure values associated with the pneumatic pressure values are used to correct the linear force error are stored for the entire working spectrum of the roller pair 4, 5.

The data memory 15 is connected to analog outputs 16, 17, 18, to each of which a pressure value characterizing, electrical signal is pending.

The output 16 is connected to an electro-pneumatic proportional valve 19, which reduces in response to the electrical input signal provided by a compressed air source 20 pneumatic pressure to a desired value. The pneumatic output of the proportional valve 19 is connected via a pressure line 21 to the input of a volume amplifier 22, which allows the inflow of a compressed air volume via a line 23 into the bellows 13, depending on the primary pressure on the line 21 in the bellows 13, in this is the for Achieving the desired line force in the working gap 6 has built up necessary pneumatic pressure. The latter is made possible by coupling a measuring line 24 to the line 23, whose end is connected to a pressure-voltage converter 25, which is associated with the detected pressure value in the electrical signal and via an electrical line 26 to an input 27 of the data memory 15 comprehensive programmable logic controller 30 supplies , With the thus detected difference between the actual and setpoint, the voltage applied to the output 16 signal is corrected until applied to the pressure-voltage converter 25 of the desired pneumatic pressure.

The output 18 of the programmable logic controller 13 is connected to the bellows 14 with the interposition of the same components, which are thus marked with the same reference numerals, but with a 'supplemented. The measurement of the pneumatic actual pressure in the bellows 14 is in turn carried out by coupling a pressure-voltage converter 25 'via a line 24', wherein the electrical output of the pressure-voltage converter 25 'via an electrical line 26' connected to an input 28 for the purpose of setpoint-actual value adjustment is.

The electrical output 17 of the programmable logic controller 30 is also connected to an electro-pneumatic proportional valve 29, at the output of which provided by the compressed air source 20 pneumatic pressure is present at a predetermined by the pending at the output 17 electrical signal reduced amount. This reduced pneumatic pressure is applied via a pressure line 31 to the control input of a pneumatically-hydraulically acting overflow valve 32.

The spill valve 32 is connected via a hydraulic supply line 33 with a hydraulic source 34, the hydraulic fluid under a required pressure in a required amount is available. Depending on the pending via the pressure line 31, pneumatic control pressure hydraulic fluid via the supply lines 7 and 8, the rollers 1, 2 is supplied via a hydraulic line 35.

For the setpoint-actual value comparison and a corresponding readjustment, a pressure-voltage converter 36 is connected to the hydraulic line 35 via a measuring line 38. Its output is connected to an input 40 of the system-programmable controller 30 with an electrical line 39, so that by means of this, an influencing of the signal pending at the output 17 can be carried out in the sense of a desired actual value compensation.

In contrast, in the belonging to the prior art, in Fig. 2 schematically illustrated device only a control of the hydraulic pressure as a function of the pneumatic pressure mechanically by a pneumatic, ratio controller comprehensive arithmetic unit 37, due to the limited work areas of the pneumatic / hydraulic ratio controller, the working range of the roller pair 1, 2 could not be exhausted.

LIST OF REFERENCE NUMBERS

1

upper roller

2

lower roller

3

squeeze rolls

4

roll shell

5

roll shell

6

working gap

7

supply

8th

supply

9

throttle

10

throttle

11

derivation

12

derivation

13

bellow

14

bellow

15

data storage

16

output

17

output

18

output

19

proportional valve

20

Compressed air shaft

21

pressure line

22

volume booster

23

management

24

Measurement line

25

Pressure-voltage transducer

26

electrical line

27

entrance

28

entrance

29

Pressure-voltage transducer

30

system programmable control

31

pressure line

32

overflow

33

hydraulic line

34

hydraulic source

35

hydraulic line

36

Pressure-voltage transducer

37

Calculated values

38

Measurement line

39

electrical line

40

entrance

L

line

Claims (10)

1. Method for setting the linear force in the working nip of a pair of rolls which comprises at least one hydraulically controlled deflection roll and a pneumatically actuated device for throwing on the rolls,
   in which the linear force is set by predefining a pneumatic actuating pressure and adapting the hydraulic pressure with the effect of minimizing the linear force error,
   characterized
   in that the hydraulic pressure values assigned to the pneumatic pressure values for the entire working range of the pair of rolls (3) are stored in a data memory (15), and
   in that these data are used to drive at least one electro-pneumatic proportional valve (19, 19') for actuating the device for throwing on the rolls (1, 2) and to drive a hydraulic source (34) providing the hydraulic actuating pressure for the at least one controlled deflection roll.
2. Method according to Claim 1, characterized in that by means of the data for the hydraulic pressures, an electro-pneumatic proportional valve (29) is driven and, by means of the resultant pneumatic pressure, a pneumatically actuated unit influencing the hydraulic pressure is driven.
3. Method according to Claim 2, characterized in that the unit comprises a pneumatically-hydraulically acting bypass valve.
4. Method according to one of Claims 1 to 3, characterized in that the pneumatic and hydraulic pressures are measured and the measured values are used for the set point-actual value comparison.
5. Method according to Claim 4, characterized in that the set points and actual values are fed to a control device, which influences the pneumatic and hydraulic pressures with the effect of minimizing the difference between the set points and actual values.
6. Device for treating a web of material,
   having a pair of rolls (3) forming a working nip (6), of which at least one roll (1, 2) is constructed as a hydraulically controlled deflection roll,
   and having a pneumatically actuated device for throwing on the rolls, the line force in the working nip (6) being set by predefining a pneumatic actuating pressure and adapting the hydraulic pressure with the effect of minimizing the linear force error,
   characterized
   in that the device has a data memory (15), in which hydraulic pressure values assigned to the pneumatic pressure values for the entire working range of the pair of rolls (3) are stored, and
   in that the data memory (15) is provided in a programmable logic controller (30) which comprises signal outputs (16, 17, 18), on which electrical signals correlating with the pneumatic and hydraulic pressures are present, the signal outputs (16, 17, 18) being operatively connected to the units (19, 19', 29) influencing the pneumatic and the hydraulic pressure, respectively.
7. Device according to Claim 6, characterized in that the unit (19, 19', 29) influencing the pneumatic pressure comprises an electro-pneumatically acting proportional valve (19, 19', 29).
8. Device according to Claim 6 or 7, characterized in that the unit influencing the hydraulic pressure comprises an electro-pneumatically acting proportional valve (29) which, on the pneumatic side, is operatively connected to a unit for influencing the hydraulic pressure.
9. Device according to Claim 8, characterized in that the unit for influencing the hydraulic pressure comprises a pneumatically actuated hydraulic bypass valve (32).
10. Device according to Claim 9, characterized in that pneumatically/electrically and hydraulically/ electrically acting measuring units (25, 25', 36) are provided to measure the pneumatic and hydraulic actuating pressures.

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