EP0950758A2 - Pressing arrangement - Google Patents

Abstract

The press station, for the extraction of water from a wet fiber web, has powered rollers (6,7) forming press gaps (2,3) at a center roller (4), where one roller (6) has a controlled drive power or speed according to a set nominal value. The other powered roller (7) is neither controlled for drive power nor speed. Or both rollers (6,7) are controlled, and the drive power ratios are constant and/or the ratio of the linear forces is matched to both press gaps (2,3). The powered rollers (6,7) have cylindrical press mantles, with shape stability. The press gaps (2,3) are at a gap from each other, with the controlled press roller (6) after the roller (7) without control in the direction of web travel (8). The flexible press mantle (5) of the center roller (4) is supported internally, at least partially. At least one flexible belt passes through both press gaps (2,3), pref. a powered belt as a blanket, fourdrinier or a press belt. The belt enters the first press gap (3) at a tangent to the powered roller (7), and exits at a tangent to the other press roller (6). The max. linear force applied at the leading press gap (3) and/or its drive power is at least within a given range according to the action at the trailing press gap (2). The press roller (6) at the trailing press gap (2) operates at a higher power than the leading roller (7) at the first press gap (3), with a control action on both rollers (6,7) according to the ratio of the max. linear forces of both rollers (6,7). The ratio between the max. linear forces of both rollers (6,7) is held at a constant level, with a power or current nominal value to both rollers (6,7) which is proportional and pref. equal to the constant ratio of the max. linear forces. The constant ratio value is ≤ 1, and the ratio of the power or current nominal value equals the constant ratio of the max. linear forces. The internal support (10) for the flexible mantle (5) of the center roller (4) is at the two press gaps (2,3), with pressure adjustment to set the max. linear forces. The pressure applied by the leading internal support (10) is set according to the pressure at the trailing support (10). The pressure at the trailing mantle support (10) is controlled according to a nominal value, which is used to control the pressure applied by the leading support. The control for the trailing mantle support (10) is pref. through a central proportional pressure reduction valve, linked to a hydraulic pressure supply. The leading mantle support (10) is controlled by an additional valve, and pref. an additional proportional sequence valve with a DELTA P function and adjustable within a given range according to the pressure at the trailing support. The additional valve is monitored by a further valve, and pref. a proportional sequence valve with a DELTA Pmax function which opens on breaching a given differential pressure value and gives a pressure compensation between the two supports (10). The press rollers (6,7) can be fitted with pliable mantles, with inner supports opposite the mantle supports (10) at the center roller (4), working at the same pressures.

Description

The invention relates to a press arrangement for the treatment of web-shaped Material or a material web in several press nips, consisting from a roller that has an internally supported flexible press jacket owns and with at least two other driven rollers each forms a press nip.

Such an arrangement is known for example from DE-OS 43 21 404 and serves there to drain a fibrous web. Such one compact arrangement, however, prepares particularly with regard to the drive the reel problems. In particular, it can also change unfavorable mechanical loads on the flexible press jacket come.

The flexible press jacket allows for example by the support concave shaped support elements the formation of in the web running direction extended press nips. On the other hand, the flexible one requires However, the press jacket also synchronizes the speed as precisely as possible the driven rollers, otherwise there will be a deformation of the jacket is coming. A mechanical or electronic coupling of the drives is very expensive.

The invention is therefore based on the object of a press arrangement to create the type mentioned in the simplest possible and exactly the same speed of the driven rollers becomes. In addition, one should over the entire speed and Line force range of the press arrangement as constant as possible as well as gentle mechanical stress on the flexible press jacket be assured.

According to the invention this object is achieved in that one of the driven rollers the drive power or the speed accordingly a predetermined setpoint is regulated.

For further simplification, the drive power can be regulated or the speed of the other driven roller become. The result is the coupling over the flexible Press jacket with the unregulated roller the same speed as with the regulated roller.

Because the drive power is largely used for friction and compression must be, it is advantageous to drive both to control driven rollers and the ratio according to the circumstances to keep constant and / or the ratio of the line forces adjust the two corresponding press nips.

This takes account of the circumstance in an advantageous manner borne that the line forces have a decisive influence on the required Have drive power.

For a simple drive of the rollers is a cylindrical, as stable as possible Press jacket an advantage.

Due to the use of the flexible press jacket for coupling between the press nips, however, can still be used, albeit in a small amount Scope come to a deformation of the press jacket. To that To counteract this, the press nips should be as close as possible from each other and the regulated roller in the web running direction be arranged after the unregulated roller. As a result, speed differences result only for limited deformation of the short Section between the press nips.

However, it is also possible to run the flexible press jacket between to support the press nips at least partially.

As an additional element for coupling between the press nips also a belt, for example in the form of a felt, sieve or press belt be passed through the two press nips, which is preferably should be driven itself. To make the coupling efficient, the belt should be guided in such a way that it is approximately tangential to the first press nip leaves with respect to the driven roller and approximately tangentially with respect the driven roller runs in the second press nip.

The press arrangement is particularly suitable for drainage and / or Smoothing of paper, cardboard or tissue webs.

The object on which the invention is based is further developed according to the invention solved in that the maximum line force and / or the drive power of a front nip viewed in the web running direction at least within a certain range depending on the maximum line force or the drive power of one in the direction of web travel considered rear press nip is controllable and / or adjustable.

Because of this training, one is over the entire speed and Line force range of the press arrangement as constant as possible as well as gentle mechanical stress on the flexible Press sleeve ensured.

A preferred practical embodiment of the invention Press arrangement is characterized in that the rear press nip associated rear driven roller with a higher drive power can be operated as the front press nip assigned to the front driven roller and that the ratio of the driving powers of the two driven rollers depending on the ratio of the maximum Line forces of these two driven rollers control and / or is adjustable. After the rear driven roller with a higher drive power than the front driven roller, ensures that the flexible press jacket during normal Operation is always biased towards the rear press nip.

It is also advantageous if the ratio between the maximum line force of the front press nip and the maximum line force of the rear Press nip kept constant and the ratio between the drive power or the current setpoint of the front driven roller and the drive power or the current setpoint of the rear driven Roller proportional and preferably equal to the constant ratio is the maximum line forces of the two press nips. In this Fall can be the ratio between the maximum line force of the front Press nip and the maximum line force of the rear press nip in particular kept at a constant value less than 1 and the ratio the drive powers or the current setpoints of the driven ones Rolling equal to this constant ratio of the maximum line forces be. By the ratio of the maximum line forces of the two Press nips smaller than 1 is also ensured at the same time that the drive power of the front driven roller remains lower than that of the rear driven roller and accordingly the flexible one Press jacket remains biased towards the rear press nip.

In an expedient practical embodiment, the flexible Press roll having roller in the area of the front and rear press nip each by at least one pressurizable Support element supported from the inside and the maximum line force of each Press nip can be adjusted accordingly via the pressure in question be. In this case, it is advantageous if the pressure of the area of the rear press nip provided support element depending on a specifiable setpoint can be controlled and / or regulated and the pressure of the depending in the area of the front press nip support element is adjustable by the pressure of the rear support element. Here can the rear support element via a central valve, preferably a central proportional pressure reducing valve, with a hydraulic one Pressure source connected and the front support element via an additional Valve, preferably an additional proportional follower valve with ΔP function, in a certain range depending on the pressure of the rear support element to be adjustable.

It is advisable to monitor the function of the additional valve another valve, preferably a proportional sequential valve with ΔPmax function, provided that when a particular one is exceeded differential pressure value determined by area ratios opens to if necessary for a pressure equalization between the rear and the to provide front support element.

In principle, the driven rollers can also each have at least one a support element arranged in the area of the relevant press nip be supported from the inside. In this case, they are opposite each other Support elements of a respective driven roller and the roller provided with the flexible press jacket of the same in each case Pressure can be applied.

In a preferred practical embodiment, at least one of the driven rollers has an at least essentially dimensionally stable, cylindrical press jacket.

In certain cases it can be beneficial if through the two Press nips at least one preferably driven belt, in particular a felt, sieve or a press belt.

The press arrangement according to the invention can be used in particular for drainage and / or smoothing a fibrous web, such as in particular a paper, Cardboard or tissue web may be provided.

Fig. 1

eine schematische Darstellung einer Ausführungsform einer ersten Preßanordnung,

Fig. 2

eine schematische Darstellung einer weiteren Ausführungsform einer Preßanordnung mit einem durch beide Preßspalte geführten angetriebenen Band,

Fig. 3

eine schematische Darstellung einer weiteren Ausführungsform einer Preßanordnung und

Fig. 4

ein Prinzipschaltbild zur hydraulischen Steuerung der Preßanordnung gemäß Fig. 3.

The invention is explained below using exemplary embodiments with reference to the drawing; in this show:

Fig. 1

1 shows a schematic representation of an embodiment of a first press arrangement,

Fig. 2

2 shows a schematic representation of a further embodiment of a press arrangement with a driven belt guided through both press nips,

Fig. 3

a schematic representation of a further embodiment of a press arrangement and

Fig. 4

3 shows a basic circuit diagram for the hydraulic control of the press arrangement according to FIG. 3.

In the two embodiments according to FIGS. 1 and 2 there is Press arrangement each from a roller 4 with an internally supported flexible press jacket 5, with two further, driven rollers 6 and 7 each form a press nip 2, 3. One of the driven Rollers, here e.g. the roller 6, the drive power or the speed regulated according to a predetermined setpoint. Through the Coupling via the press jacket 5 arises in the driven roller 7 automatically set the same speed.

The flexible press jacket 5 is in the area of the press nips 2, 3 of each a preferably hydraulic support element 10 with a concave trained, hydrodynamically and / or hydrostatically lubricated Press surface supported. This leads to the formation of long Press nips 2, 3.

In order to reduce the load on the flexible roll shell 5, the Press rolls 6, 7 are arranged at the smallest possible distance from one another. The regulated roller 6 is in the web running direction 8 according to the Roller 7 arranged. In addition, the flexible roll shell 5 is between the press nips 2, 3 partly via guide elements 11 in the form of Rollers, strips or the like supported so that deformation of the roll shell 5 very strong at speed differences of the rollers 6, 7 can be reduced.

The driven rollers 6, 7 have e.g. a dimensionally stable, cylindrical Press jacket, which can also be supported on the inside. These rollers 6, 7 can, however, also be formed by solid rolling, for example. There is preferably an electric drive on the axis of the rollers 6, 7 coupled.

In the embodiment according to FIG. 1, only the fibrous web 1 is through the press nips 2, 3 performed, whereby smoothing is achieved. In the 2 is a press arrangement for dewatering the fibrous web 1 shown. For this reason, the flexible press jacket is wrapped around it endless belt 9 in the form of a press felt through both press nips 2, 3 out. On the other side of the fibrous web 1 runs through each press nip 2, 3 a separate endless press felt 12 or 12 '. The press felts 12, 12 'serve to receive and discharge the in the press nips 2, 3 squeezed water. The belt 9 is between the press nips 2, 3 passed over a suction guide roller 13, so that the belt 9 the first Press nip 3 leaves approximately tangential with respect to the driven roller 7 and approximately tangential to the driven roller 6 in the second Press nip 2 runs in. The guide roller 13 is also drivable, so that additional Drive power can be introduced into the press nips 2, 3.

3 shows a further embodiment in a schematic representation a press assembly shown. A basic circuit diagram for hydraulic Control of this press arrangement is shown in FIG. 4.

This press arrangement also serves to treat a material web 1 such as in particular a fibrous web in several press nips 2, 3. It also comprises a roller 4, which is supported by support elements 10 has internally supported flexible press jacket 5 and with two more driven rollers 6, 7 each extended in the web running direction 8 Press nip 2, 3 forms.

The driven rollers 6, 7 have a dimensionally stable, cylindrical Press jacket in the area of the relevant press gap 2, 3 by at least a support element 14 can be supported from the inside. It is preferably each an electric drive coupled to the axes of the rollers 6, 7.

The two press nips 2, 3 can again separate separate press felts 12 or 12 '. There can also be one through both press nips 2, 3 guided endless belt 9 is provided in the form of a press felt be that between the two press nips 2, 3 together with the material web for example, is guided over a guide roller 13.

The front press nip 3 viewed in the direction of web travel 8 can be used as an inlet nip and the rear nip 2 viewed in the direction of web travel 8 as Outlet nip are considered. The front is driven accordingly Roller 7 an inlet roller and the rear driven roller 6 one Outlet roller.

The rear press nip 2 is operated as a master, as its slave the front press nip 3 is to be considered. The front one to be considered a slave Press nip 3 is preferably only dependent in each mode operated by the master. This dependency is firstly the structure of the hydraulic control and Control concept and on the other through a corresponding tax and Control software ensured. The different operating modes of the press nips 2, 3 are "close", "transfer", "load" and "open". The the flexible press jacket 5 having roller 4 is not driven. The two driven rollers 6, 7, which are basically also by solid rollers can be formed, for example, part of a multi-motor drive a paper machine. The maximum line force MLK the Press nips 2, 3 is a function of the pressure in the present case Support elements 10 and optionally 14th

According to the hydraulic concept resulting from FIG. 4, the hydraulic Pressure oil supply to the entire system via a central 2-way switching valve Y1 provided with which the presses in the switching state "a" in the operating modes "Close", "Transfer" and "Load" and in Switching status "b" can be operated in the "Open" operating mode.

The pressure in the system that makes up the maximum line forces for MLK the presses are produced via a central proportional pressure reducing valve Y2 set.

The maximum line force MLK of the front press nip 3 can be about additional proportional sequence valve Y3 with ΔP function in a certain one Range varies depending on the rear press nip 2 become.

The pressure in the front press nip 3 is thus due to hydraulic Losses that can be around 2%, for example, are always below the pressure in the rear press nip 2.

The function of the proportional sequential valve Y3 with ΔP function becomes hydraulic monitored by another sequence valve PV1 with ΔPmax function and operated hydraulically so that when a particular one is exceeded value determined by area ratios, i.e. in particular a pressure difference value, which opens the sequence valve PV1 with ΔPmax function and ensures pressure equalization in the two systems. In the case an accident occurring in the hydraulic system is always affected both press nips 2, 3 out.

The operation of the two press nips 2, 3 and the electrical control result from the following:

The two press nips 2, 3 are operated together, for example via four buttons or comparable elements to the states Control "Close", "Transfer", "Load" and "Open".

The maximum line force in the rear press nip 2 is in the operating states "Transfer" and "strain" by the pressure in the support sources or support elements 10 and optionally 14 regulated. This can for example via a potentiometer or a comparable element Setpoint to be supplied to the control and regulation system. This system then compares the value with the current one from a pressure transducer originating actual value and gives a corresponding setpoint to the proportional pressure reducing valve Y2 continue.

The maximum line force in the front press nip 3 is also in the operating states "Transfer" and "debit" regulated. This regulation takes place however depending on the rear press nip 2. Inside a fixed area, e.g. 50 to 95% of the maximum line force MLK of the rear press nip 2 can be, the pressure in regulated in the manner described above, but as an actuator here the proportional sequential valve Y3 with ΔP function is used.

An example of controlling the variable load distribution of the two Drive motors result from the following:

In conventional non-positive drive combinations, the Drives with a load distribution control, in which the load ratio is fixed is set, operated. One of the (two) drives is the Main drive and receives a speedometer for speed measurement. A speed controller gives parallel (two) current setpoints to those assigned to the drives Current regulator, the load (torque) in the specified ratio keep constant.

In the present embodiments of the press arrangement according to the invention it is now important that the flexible press jacket 5 between the the inlet nip forming front press nip 3 and the outlet nip forming rear press nip 2 always runs taut. This is achieved that the drive of the rear driven forming the outlet roller Roller 6 is operated with a higher load than the drive of the Front roller 7 forming the inlet roller.

In order to ensure the power transmission for the flexible press jacket 5 as gently and consistently as possible over the entire speed and linear force range, the load ratio between the drives is determined, for example, as follows based on the ratio between the maximum line force MLK of the inlet nip 3 and the maximum line force MLK Outlet nips 2 bound: Load ratio = Current setpoint drive inlet roller Current setpoint drive runout roller = MLK enema - Nip MLC spout - Nip = k

The hydraulic concept and the electrical control ensure that that the load ratio is always less than 1.

The corresponding relationships also result from the following Derivation:

The current consumption of the drives is proportional to the output Torque.

M_E = Drehmoment der Einlauf-Walze

M_A = Drehmoment der Auslauf-Walze

M = Fr·r

Fr = Fn·µ

Fn = A·p

mit:

Fr = Reibkraft

Fn = Normalkraft und µ = Reibfaktor

A = Fläche des Schuhs

p = Druck auf den Schuh

r = Walzenradius

The total torque is made up of the sum of the torques. M Ges = M E + M A With:

M _E = torque of the infeed roller

M _A = torque of the outlet roller

M = Fr · r

Fr = Fn · µ

Fn = AP

With:

Fr = frictional force

Fn = normal force and µ = friction factor

A = area of the shoe

p = pressure on the shoe

r = roller radius

This results in the torque of the infeed roller: M E = µ E · A E · R E · P E

For the torque of the outlet roller, the following results: M A = µ A · A A · R A · P A

The following relationship applies to the total torque: M Ges = µ E · A E · R E · P E + µ A · A A · R A · P A

With the same geometrical relationships: µ E ≈ µA ≈ µ A E = A A = A r E = r A = r where µ _E ≤ µ _A
and thus: M Ges = µ · A · r (p E + p A )

When the roll pack rotates, (µ · A · r) is a constant, from which it follows: M Ges ∼ (p E + p A )

With the simplified relationship for three-phase motors: I. Ges ∼ M Ges with I _Ges = active components of the rotor currents of the motors

This results in: I. Ges ∼ (p E + p A )

With the stipulation that the maximum line force MLK and thus the pressure p _E in the inlet nip 3 is smaller by a factor "k" than the pressure p _A in the outlet nip 2: I. Ges ∼ p A · (K + 1) with: p E = kp A (0.5 <k <1)

If the factor "k" is now also used on the current side, the result is: I. Ges = I E · K + I A

Reference list

1

Material web

2nd

extended press nip

3rd

extended press nip

4th

Roller with a flexible press jacket

5

flexible press jacket

6

driven roller

7

driven roller

8th

Web direction

10th

Support elements

11

Guide elements

12th

Press felt

12 '

Press felt

13

Guide roller

14

Support elements

Y1

2-way switching valve

Y2

Proportional pressure reducing valve

Y3

Proportional sequence valve with ΔP function

PV1

Sequence valve with ΔPmax function

Claims (21)

Press arrangement for treating a material web (1) in a plurality of press nips (2, 3), consisting of a roller (4) which has an internally supported flexible press jacket (5) and at least two further driven rollers (6, 7) each forms a press nip (2, 3),
characterized by
that in one (6) of the driven rollers (6, 7) the drive power or the speed is regulated according to a predetermined setpoint. Press arrangement according to claim 1,
characterized by
that in the other driven roller (7) neither the drive power nor the speed is regulated. Press arrangement according to claim 1,
characterized by
that the drive power of both rollers (6, 7) is regulated and the ratio of the drive powers is constant and / or the ratio of the line forces of the two corresponding press nips (2, 3). Press arrangement according to one of the preceding claims,
characterized by
that the driven rollers (6, 7) have an at least substantially dimensionally stable, cylindrical press jacket. Press arrangement according to one of the preceding claims,
characterized by
that press nips (2, 3) are arranged at the smallest possible distance from each other and the regulated roller (6) is arranged in the web running direction (8) after the unregulated roller (7). Press arrangement according to one of the preceding claims,
characterized by
that the barrel of the flexible press jacket (5) is at least partially supported from the inside between the press nips (2, 3). Press arrangement according to one of the preceding claims,
characterized by
that through both press nips (2, 3) at least one preferably driven belt (9) such as in particular a felt, sieve or a press belt is guided. Press arrangement according to claim 7,
characterized by
that the belt (9) is guided such that it leaves the first press nip (3) approximately tangentially with respect to the driven roller (7) and runs approximately tangentially with respect to the other driven roller (6) into the second press nip (2). Press arrangement according to one of the preceding claims for treating a fibrous web (1), in particular a paper, cardboard or tissue web,
characterized by
the press arrangement serves for dewatering and / or smoothing the fibrous web (1). Press arrangement for treating a material web (1) in a plurality of press nips (2, 3), with a roller (4) which has an internally supported flexible press jacket (5) and with at least two further driven rollers (6, 7) each Press nip (2, 3) forms, in particular according to one of the preceding claims,
characterized by
that the maximum line force and / or the drive power of a front press nip (3) viewed in the direction of web travel (8) control at least within a certain range depending on the maximum line force or the drive power of a rear press nip (2) viewed in the web direction (8) and / or is adjustable. Press arrangement according to claim 10,
characterized by
that the rear driven roller (6) assigned to the rear press nip (2) can be operated with a higher drive power than the front driven roller (7) assigned to the front press nip (3) and that the ratio of the drive powers of the two driven rollers (6, 7 ) can be controlled and / or regulated depending on the ratio of the maximum line forces of these two driven rollers (6, 7). Press arrangement according to claim 10 or 11,
characterized by
that the ratio between the maximum line force of the front press nip (3) and the maximum line force of the rear press nip (2) is kept constant and the ratio between the drive power or the current setpoint of the front driven roller (7) and the drive power or the current setpoint of the rear driven roller (6) is proportional and preferably equal to the constant ratio of the maximum line forces of the two press nips (3, 2). Press arrangement according to claim 12,
characterized by
that the ratio between the maximum line force of the front press nip (3) and the maximum line force of the rear press nip (2) is kept at a constant value (k) less than 1 and the ratio of the drive powers or the current setpoints of the driven rollers (7, 6) is equal to this constant ratio of the maximum line forces. Press arrangement according to one of claims 10 to 13,
characterized by
that the flexible press jacket (5) having roller (4) in the region of the front and rear press nip (3, 2) is supported from the inside by at least one pressurizable support element (10) and that the maximum line force of a respective press nip over the relevant one Pressure is adjustable accordingly. Press arrangement according to claim 14,
characterized by
that the pressure of the support element (10) provided in the area of the rear press nip (2) can be controlled and / or regulated as a function of a predeterminable setpoint value and the pressure of the support element (10) provided in the area of the front press nip (3) as a function of that Pressure of the rear support element (10) is adjustable. Press arrangement according to claim 15,
characterized by
that the rear support element (10) via a central valve (Y2), preferably a central proportional pressure reducing valve, is connected to a hydraulic pressure source and the front support element (10) via an additional valve (Y3), preferably an additional proportional follower valve with ΔP function, can be set in a certain range depending on the pressure of the rear support element (10). Press arrangement according to claim 16,
characterized by
that to monitor the function of the additional valve (Y3), a further valve (PV1), preferably a proportional sequential valve with ΔPmax function, is provided, which opens when a differential pressure value determined, in particular by area ratios, is exceeded, in order, if necessary, for pressure compensation between the rear one and to provide the front support member (10). Press arrangement according to one of claims 10 to 17,
characterized by
that the driven rollers (7, 6) are each supported from the inside by at least one support element (14) arranged in the region of the relevant press nip (3, 2) and that the opposing support elements (14, 10) of a respective driven roller (7 , 6) and the roller (4) provided with the flexible press jacket (5) can be acted upon by the same pressure. Press arrangement according to one of claims 10 to 18,
characterized by
that at least one of the driven rollers (7, 6) has an at least substantially dimensionally stable, cylindrical press jacket. Press arrangement according to one of claims 10 to 19,
characterized by
that at least one preferably driven belt (9), in particular a felt, sieve or a pressing belt, is guided through the two press nips (3, 2). Press arrangement according to one of claims 10 to 20,
characterized by
that it is provided for dewatering and / or smoothing a fibrous web (1), in particular a paper, cardboard or tissue web.

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