FI120317B - Method of treating deviations during manufacture of a material web and plant for carrying out the procedure in a calender - Google Patents

Abstract

The invention relates to a method for dealing with faults occurring during the calendering of a material web, said method comprising at least the following steps of: -identifying the location of a fault (H) on the surface of a roll (5) or in a material web and estimating or calculating an arrival time of the fault (H) at a roll nip (N) and a dwell time for the fault in the roll nip, -transmitting from a control system (4) to at least one digital valve unit (100), used for controlling a nip pressure of the roll nip (N), a feed-forward adjustment instruction (F) for dealing with a fault in the roll nip (N) of a calender, -reducing as per adjustment instruction (F), through the intermediary of at least one digital valve (1), a nip pressure of the roll nip (N) at the latest when the fault (H) arrives at the roll nip (N) and increasing the nip pressure as the fault exits the roll nip.

Description

A method for treating interference during the manufacture of a material web and apparatus for implementing the method in a calender

The invention relates to a method according to the preamble of claim 1 for treating interference during the manufacture of a material web.

The invention also relates to an apparatus according to claim 37 for carrying out the method according to claim 1 in a calender.

The invention relates to controlling the operation of parts of a fiber web machine used by hydraulic or pneumatic actuators via digital valve units.

Fiber web machine parts 10 used by hydraulic or pneumatic actuators are those machine parts whose operation can be controlled by controlling the flow rate and / or pressure of the fluid supplied to said parts. Fluid, in turn, means a liquid such as oil and water or a gas such as air.

By digital valve unit is meant a valve unit having at least one digital valve assembly which in turn includes a plurality of digital valves connected in parallel to the fluid flow through the digital valve assembly. The volume flow rate of fluid passing through the digital valve assembly is determined by the opening of the digital valve assembly, i.e., the total area of the valve openings of the digital valves that are currently open in the digital valve assembly. A digital valve, in turn, means a valve for controlling the volume flow of a fluid, which has 2-N different stepwise discrete control modes, preferably 2 different discrete control modes (open / closed) and for which the control signal from the control system is preferably digitized. The volume flow through the digital valve assembly is controlled by the difference in pressure between the fluid entering the digital valve assembly and the fluid leaving the digital valve assembly, which again depends on the opening of the open digital valve bricks. By knowing the difference in fluid pressure across the digital valve and opening of the digital valve assembly, it is possible to accurately predict the fluid volume flow through the digital valve assembly, which can be utilized for various feed-in rapid adjustments. In feed-in controls, switching combinations of fluid-permeable digital valves are selected such that the desired operation is performed in a pneumatic or hydraulic actuator connected to the digital valve assembly.

In this application, analog valve refers to a valve in which the volume flow rate through the valve (throttle, valve opening degree) depends on the magnitude of the control signal. Typical analog valves are servo and proportional valves.

By fibrous web is meant at least in part a web containing fibrous material such as wood fibers. Fibers, straw, bagasse, grass etc. can also be used as fiber material.

There are several disadvantages in adjusting the pressure and / or flow of fluid entering the hydraulic actuator to the value of the control signal proportional to the value of the control valve: valve details). This greatly increases the design work on systems with analog valves.

- Analog valves are largely made in single pieces or in small pieces, which increases their manufacturing cost.

-Analogic valves exhibit fluctuations in control, especially if there are significant differences in the fluid flow through the valve between the control initial state and the final control state. Slack adjustment causes slower adjustment and increased energy consumption. The deceleration of the control is further increased by the necessary internal feedback of the slide valve 20, which controls the position of the slide valve when running the valve from volume flow A to volume flow B.

More particularly, the invention relates to a method according to the characterizing part of claim 1 and to an apparatus according to claim 37 for carrying out the method of claim 1 in a calender.

25 By replacing the analog control valve with a digital digital valve assembly, there is considerable advantage in controlling the hydraulic actuators used in paper machines and overcoming the problems of the prior art: -Similar digital valves and digital valve assemblies can be used for many different purposes, i.e. digital valves. The operation and availability of the digital-30 valve group depends on its control, since there is no difference between the digital-valve groups in the structure of the digital valves they contain.

3 -Digital valves are a cheap mass product because they are only required in a few sizes, regardless of the purpose, that is, the design and operation of the hydraulic actuator controlled by the digital valves.

- The structure of the individual digital valve is simple, so that its function 5 is good reproducibility, not hysteresis.

-Digital valve group operation is fault tolerant, if one digital valve group digital valve malfunctions, other valves can compensate for its operation, i.e. the fault is "bypassed".

-Fluid filtration requirements are lower.

10 Replacing a certain analog valve in a papermaking machine with a digital valve assembly achieves a significant simplification in component design, since standardized flow valve digital valve assemblies can be used at each site instead of application-specific analog valves. This often results in significant cost savings not only in the valve design process but also in the cost of operating the valve, since the use of digital valves often also results in significant energy savings. The savings are due to the more accurate and faster availability of the digital valve group; driving an analog valve between two control modes of very different flow rates causes the control to fluctuate very easily due to control feedback. Instead, the digital valve group can perform the same operation in a feed-in control mode quickly and accurately without delay and oscillation, by adjusting the volume flow through a plurality of smaller smaller digital valves in parallel, with the total flow through for a combination of open digital 25 valves.

The control instruction (control signal) arriving to the digital valve group is digital in nature, like binary. According to the control instruction, the volume flow and pressure exerted by the digital valve group is controlled by opening a particular digital valve group valve combination so as to achieve the desired digital 30 valve group opening and fluid volume flow. Unlike the analog valve, each digital valve connected in parallel can have only a limited number of control modes, i.e. the digital valve has only certain discrete flow states. In one form of a digital valve, it has three modes: open / close / quick open. Preferably, however, the states of each digital valve are simply on / off; the valve allows the open 4 to pass through a given volume flow, and when closed, completely prevents the flow of liquid through.

In most of the embodiments of the invention described below, the digital valve assembly consists of digital valves having two modes (on / off). Thus, in a digital valve of two to five successive nominal flow rates, the flow rate through the valve having a higher nominal flow rate in the open position is always twice that of a valve having a lower nominal flow rate. Thereby, such a digital valve array can be provided with a binary control signal in which the magnitude of the control signal has been changed to 10.

As an exemplary comparison of the control mode differences between the analog valve and the hydraulic valve group, the following can be stated: if the analog valve is adjusted by a control signal (control) of 12 units the spindle of the analog valve moves 12 times the opening of the valve. volume flow. In contrast, when a five-in-flow digital on / off digital valve set is controlled by a similar 12-unit control signal (control instruction), the volume flows of the digital valves 1, 2, 3, 4, 5 are respectively 1, 2, 4, 8 and 16 units, the control signal bi-20 is chewed to the control signal 01100 (0 x 24 + 1 x 23 + 1 x 22 + 0 x 21 + 0 x 2 ° = 12) (corresponding to valves 5.4, 3, 2.1) and opened valves 3 and 4.

The operation of the digital valve assembly described above with respect to the analog valve is further illustrated in Figures IA and IB. Figures 1A and 1B show the effect of the number of digital valves in the digital valve array on the achievable volume flow rates and control accuracy.

Figures 1A and 1B show the effect of the number of on / off digital valves in the digital valve assemblies on the achievable control accuracy when the digital valve assembly has 4 (Fig. IA) and 6 (Fig. IB) digital valves connected in parallel. The chart shows the relative volume flow of a digital valve group as a function of control, when in a group of digital valves, the flow through two valves with a higher flow rate is typically twice as large as the previous valve, In Fig. 35, the flow rate 0 corresponds to a situation where the opening of the digital valve set = 0, i.e. 5 does not flow through it and 1 the situation where the opening of the digital valve set is maximal, i.e. all of its digital valves are open; when N = 4, the maximum total flowrate Vmax through the digital valve assembly is Vmax = 1V + 2V + 4V + 8V = 15V and when N = 6, the maximum flowrate is 5Vmax = 1V + 2V + 4V + 8V + 16V + 32V = 61V. As shown in Figures 1A and 1B, the control response of the digital valve array rapidly approaches the response achieved by the analog slide valve when adding valves to the digital valve array, since the digital valve added to each array provides approximately double the number of possible opening combinations.

The following describes in more detail the application of the invention to the adjustment of the various parts and functions of the papermaking machine, and the advantages thereof. In the examples presented several references are made to the application of the invention to adjusting a parameter in a roll nip. By roll nip in this application is meant a roll nip between two rolls or also a roll nip between roll and belt unless otherwise indicated. The belt may be, for example, a metal, polymeric, felt-like or wire belt.

The invention is then illustrated by the following figures:

Figures 1A and 1B show the effect of the number of digital valves in the digital valve array on the achievable volume flow rates and control accuracy.

Fig. 2A schematically shows a multi-roll calender, viewed directly at the end of the calender.

Fig. 2B illustrates the control of the load pressure of two support rollers at the end of the intermediate rolls by hydraulic actuators controlled by a digital hydraulic unit.

Fig. 2C is a schematic representation of the flow and fluid flows of control of the second hydraulic actuator of Fig. 2B.

Fig. 2D shows synchronized control of a hydraulic actuator coupled to support arms at the ends of two intermediate rollers with two separate digital valve units.

Figure 3A is a schematic representation of generating a relief and return pulse on a roll in a roll of a multi-roll calender using a digital valve assembly when a failure of Figure 3B arrives at the roll; the figure shows the flows of hydraulic fluid in the hydraulic actuator and the loading pressure of the roll.

6

Fig. 3B shows a roll nip between two rolls with a seam between the two fibrous webs, viewed directly at the end.

Figure 3C shows the control of the steady-state of the intermediate roll support lever by the digital valve unit before generating the relief and return pulse of Figure 3A.

Figure 3D shows the control of the intermediate roll support lever by the digital valve assembly during the lightening pulse of Figure 3A.

Figure 3E shows the control of the intermediate roll support lever by the digital valve assembly during the return pulse of Figure 3A.

Fig. 3F is a direct view of the end showing a roll nip between two rolls which is about to enter a web break on the fibrous web.

Figure 3G shows the hydraulic fluid flows in the hydraulic actuator for the quick opening of the roll roll nip of the multi roll calender 15 by digital hydraulic units, and the corresponding roll position in the roll roll nip.

Fig. 3H illustrates the pressure and flow conditions in the quick release of the roll nip between the two intermediate rolls of the multi-roll calender, the control pressure of the support lever on the hydraulic cylinder, the cylinder piston head and the piston rod side.

Figure 4A is a schematic view of a long nip calender viewed directly at the end of the calender.

Figure 4B is an enlarged view of the longitudinal nip area of the calender of Figure 4A.

Fig. 5 schematically controls an oil-in-water heat exchanger with a digital hydro-25 roulette unit.

calendering

Currently, analogue slide valves are used for adjusting the hydraulic actuators of the calender for paper or cardboard calendars, such as hydraulic cylinders, in which the position (flow, pressure) of the slide is proportional to the value of the control reference (oh 7 diverting signal). Typical applications where the calender hydraulic actuators are controlled by analog slide valves include: -pressure of the hydraulic cylinders connected to the lower and / or upper roller of the multi-roll calender to control the pressure of the roller nipples as well as the opening of the nipples during interruptions; - adjusting the loading of the roll nipples of the multi-roll calender by changing the loading pressure of the hydraulic actuators on the supporting levers acting on the ends of the intermediate rolls; adjusting the total pressure of the roller nip of the multi-roll calender and the pressure profile in the CD direction of the roller by varying the loading pressure of the internal loading means (hydraulic actuators 10 that exert pressure on the inside of the roll from the roll shell). A typical such roll is the applicant's so-called sym roll; quick opening of multi-roll calender roll nipples in disruptions such as track breaks by rapidly reducing the loading pressure of the respective loading cylinders to the support levers at the ends of the intermediate rolls and to the upper and / or lower calendars of the calender; 15 Multi-roll calender roller nip load reduction when replacing calender-driven fibrous web (head thread). Here, the multi-roll calender may be lever-loaded, i.e., the roll nipples are loaded by hydraulic cylinders connected to the supporting levers at the ends of the intermediate rolls or by loading means used by the internal hydraulic actuators of the rolls.

20 Controlling the operation of hydraulic calipers performing various calender functions (load profile and load changes on track roll nipples, roll nipple opening / closing and threading) with servo or proportional valves (slide valves) proportional to the control value of the control signal specifically for a particular flow channel (nominal valve size and, within the size range, the size of the valve flow openings), which greatly increases the design work for systems containing hydraulic components;

Hydraulic actuator controls implemented with slide valves are susceptible to failure, and in addition, the electronics of the slide valve control components are susceptible to thermal degradation and high temperature damage; 8

Slide valves are designed as single pieces, making spare parts easily expensive;

The efficiency of the gate valves is relatively poor due to the sway of the adjustment;

In embodiments with slider valves, the sensor has to be doubled due to the feedback of 5 adjustments.

In the invention, the hydraulic actuators of the calender are controlled by digital valve groups of the digital valve unit, which replace all or part of the previously used slide valves. The digital valves contained in the digital valve assemblies have the same structure, the only difference between the parallel connected digital valves is in the flow rate they allow through the valves in the open position. In addition, if the flow rates through the group digital valves are properly designed, the failure of one of the valves can be practically compensated by appropriately changing the flow rates through the other valves. The digital valves themselves do not contain much control electronics, but they are controlled by a separate hardware-specific control system.

For the reasons stated above, several advantages are obtained when the slide pressure valves controlling the hydraulic actuator load pressure are replaced by one or more digital valve groups: - The digital valve assembly has little control electronics, so that thermal aging of its electronic components and ability to withstand temperature and vibration will not be a problem; -When using digital valve groups with quick adjustment response, so-called feed-forward type control strategies can often be used to control the operation of the hydraulic valves, thus making the sensors simpler than the feedback control strategies used with the slide valves, where - By replacing the slide valve with one or more digital valve groups, efficiency gains of up to 30 -50% can be achieved in many applications; 9 In digital valve groups, all digital valves have the same standard components in technical design, which makes replacing the faulty component much cheaper than a slide valve.

- Synchronizing the control of the hydraulic actuators at each end of the roller is considerably easier by using digital valve units than in the conventional way. Conventionally implemented, the control of two hydraulic actuators at different ends of the roll is based on power distribution devices, stiffeners of actuators Saija and / or actuator-specific control of each parallel actuator by means of feedback control via servo / proportional valves. By using 10 precise digital valve units, parallel actuators can be controlled in parallel by two separate digital valve units or by a single digital valve unit using flow distributors.

Changing the load on the calender support levers

In the following, one embodiment of the invention, i.e. control of the hydraulic actuators acting on the roller nip pressure of the calender 15 by digital valve assemblies and the control of the same hydraulic actuators with analog valves for adjusting nipple loading, quick nip rolls and quickening of roll nipples, will be discussed. The examples illustrate the application of an embodiment of the invention to a multi-roll calender, but the invention can also be applied to single-nip calenders.

State of the art

Figure 2A schematically shows a multi-roll calender 500, viewed directly at the end of the calender.

The multi-roll calender 500 25 shown in FIG. 2A having a known structure comprises alternating heatable rolls and polymer-coated rolls. Typically, there are 6 to 16 such thermal rollers and polymer coated rolls in a multi roll calender; e.g., the so-called Optiload calender used by the applicant typically has 6-12 rolls, of which 2-5 are thermal rolls and 4-7 are polymer coated rolls. The roller 50 of the multi-roll calender 500, exemplified in the figure, has 6 to 30 rolls having internal loading means for varying the line pressure profile in the roll nip N between two rolls. At least the top roll 5, 5c and bottom roll 5, hydraulic actuators (hydraulic cylinders) 2; 20; 202,201 for pressurizing the track in the vertical direction. Top roll 5; 5c and the lowest roll 5; Connected between the 5b four four deflection compensated intermediate rolls 5; 5a with support arms 3 connected to the calender body 55 at the ends. 20. In addition, the support levers 3 adjust the deflection of the intermediate rolls 5a due to the weight of these rolls 5a and the bearing loads at the ends of the rolls.

When, for example, Figure 2A of the multiroll calender 500, for example 2A, a split roller of Figure 5a, the supporting lever 3 against, obtained the hydraulic cylinder October 20 load controlled by an analog slide valve, which regulates the flow and / or pressure of hydraulic fluid on either side (both on the piston rod side and the piston head side), it is necessary to control strategy based on the adjustment of the cylinder piston side of the volume flow (and thereby pressure) feedback. This causes problems especially with fast adjustment operations, such as opening of the roll nip N 15 and rapid changes in the loading pressure of the roll nip N, especially if the loading pressure of the roll nip N provided by the hydraulic cylinder has to be significantly changed. The spool valve has a significant internal delay due to the internal valve feedback and, in addition, large volume flow changes result in a volumetric flow (and pressure) outflow from the valve due to the valve feedback control strategy. This reduces the speed and efficiency of the slide valve adjustment and reduces efficiency. It is impossible to quickly change the volume flow to the pressure and working side of the hydraulic cylinder by means of a slide valve, but in practice the back pressure adjustment on the hydraulic cylinder side has to be limited to passively changing the flow on the piston as a function of fluid flow and pressure. As a result, the slide valve N is unable to perform a fast opening of the roll nip N in the event of a failure or a rapid reduction of the load on the roll nip.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

By the method according to the invention, using a digital valve assembly, it is possible to precisely and quickly control both the hydraulic cylinder 2; 20 fluid pressure and flow rate of hydraulic fluid on the pressure side (piston head side) as well as the counter pressure and flow rate of hydraulic fluid on the working side of the hydraulic cylinder (piston rod side). This is achieved by the digital valve group quick adjustment response to the digital control instruction and the non-feedback volume flow through the digital valve groups of the 35 digital valve units. The latter advantage is due to the fact that the digital valve assembly includes a plurality of small digital valves through which the flow rate is always constant in the au-open position, so that each opening of the digital valve assembly has a good differential pressure between the fluid coming from the valve and the fluid leaving the valve.

5 In one embodiment of the invention, the intermediate roll of the calender load of the active lever of the hydraulic pressure is set to at least one of the hydraulic cylinder's pressure and working side connected to the digital valve group, which adjust the running time as well as local-volume flow and pressure and the working side for its volume flow and pressure. In a preferred embodiment of the invention, the hydraulic cylinders that load each of the two support arms of a single roller are controlled by their own digital valve unit, which is functionally synchronized at the level of the control system. In another preferred embodiment of the invention, the action of the hydraulic cylinder loading the roll support lever is controlled by two digital valve groups connected to the pressure side of the cylinder and two digital valve groups 15 connected to the cylinder side.

In still another embodiment, the digital valve groups connected to the pressure side of the hydraulic cylinder perform a quick opening of the hydraulic cylinder.

In yet another embodiment of the invention, the pressures of the roll roll nipples of the multi-roll calender are rapidly altered by changing the pressure-to-fluid fluid pressure ratio of said hydraulic cylinders by means of digital valve groups 20 connected to the pressure and working side of the hydraulic cylinder.

according to the invention, the digital valve controlled calender support levers the loading-tuspaineen control several advantages over the prior art shown above: 25 -A digital able to control the fast and the hydraulic pressure and the working side pressure and the volume flow of the liquid, which allows the first side of the piston in the cylinder of the pressure and on the other side of the receiving active and fast adjustment of the method. The position of the piston of the hydraulic cylinder and thus the load-30 pressure exerted by the hydraulic cylinders on the support arms at the ends of the roll can be quickly adjusted to the desired level because the volume flow ratio across the piston can be quickly adjusted. This results in precise positioning of the intermediate roller support lever (load pressure) and the ability to perform a smooth and fast adjustment of the carrier lever pressure, even in confined pressures. This, in turn, enables rapid and precise adjustment of the load pressure profile between the different roll nipples of the calender and the c-directional pressure profile of the same roll nip.

12 -As constituted according to the invention, the intermediate roll supporting lever's pressure load adjustment for control lever affect the loading of the hydraulic actuator 5 for pressure and working side fluid flow (and thereby also the fluid pressure), and the ratio of liquid flow rates mentioned, consists of a control event fast and efficient and energy-good as well as the loading pressure changes at the beginning and at the end of the calendering and other changes in the load and load profile of the roll nip and in the quick opening of the roll nip and in the steady state during calendering, which aims to maintain a certain level of equilibrium pressure in the hydraulic actuator. Compared to the control of the control lever load by analogue technology, the hydraulic actuator control method of the present invention achieves about 30% to 50% energy savings by using a hydraulic actuator control method.

adjustment method according to the invention is practically non-fluctuating, because it is controlled by a hydraulic cylinder 15 on both sides of the liquid flow and liquid pressure BY quickly penetrated the variable digital valve groups and the feed-forward -säätötavalla.

Of the additional advantages of the invention, it is noted that the adjustment of the roll support lever load-20 pressure by the digital valve groups receiving the digital control instruction is more versatile than the corresponding control by the slider valves receiving the analog control. This is because the digital valve assembly is capable of operating effectively over a much wider operating range than the slide valve; the same digital valve assembly is capable of operating in both low and high volume flow to the hydraulic actuator. This is due to the structure of the digital valve assembly; each set of digital valves consists of 2 ... n separate parallel digital valves through which the volume flow rate in the open position is precisely known and from which valves the fluid flow passes freely. Thereby, it is possible for a certain number of digital valves to provide a very large number of different volume flows by opening suitable digital valve combinations. On the other hand, expanding the nominal flow and differential pressure of the spool valve will easily meet the flow limitations (laminar vs. turbulent flow), the delays caused by the internal feedback of the valve, the material technical limitations of the valve and the increase in investment costs. Further, the adjustment of the hyd-35 roll actuator by digital valve assemblies is practically non-oscillating, which is considerably more stable and faster than that of the prior art slide valves.

In the following, the loading of the calender carrying lever according to the invention implemented by digital valve assemblies is illustrated by way of example.

Fig. 2B schematically illustrates the control of a single intermediate roll of a multi-roll calender with the control of the hydraulic actuators 3 used to load the levers 3 by a single digital valve unit 100.

Fig. 2C is a schematic representation of the control data and fluid flows for another hydraulic actuator according to Fig. 2B.

Fig. 2D also schematically shows the control of the hydraulic actuators 2 used to load the support levers 3 at the ends of one of the intermediate rolls of the multi-roll calender with their own digital valve groups 100; 100 'and 100; 100 ”and synchronization of the hydraulic actuators 2 thus controlled.

Fig. 2B shows the pressure control of the support levers 3 at each end of the intermediate roll (not shown) by a digital hydraulic unit 100 according to the invention containing four digital valve groups 10. The load pressure control at each end of the intermediate roll by a hydraulic actuator 2; 20; 20 'and 2; 20; 20 ”is performed with identical waste systems, so that only the adjustment of the load pressure of the left-hand lever 20 3 will be discussed below.

Hydraulic actuator 2; The supply flow to the pressure side 20b passes through a valve unit 30 which includes a quick-opening and safety valves; they can be implemented either by conventional slide valve technology or alternatively by one or more digital valve groups.

Fig. 2B is a bottom view of a digital valve unit 100 for controlling the pressure and flow of hydraulic fluid coupled to a hydraulic cylinder 20 acting as a hydraulic actuator 2 for loading the support lever 3, replacing a conventional 4/2-directional valve (slide valve). With the digital valve unit 100 shown, two flow channels 6 can be controlled simultaneously; 61, 62 which lead respectively to the pressure and working side 20b, 20a of the hydraulic cylinder 20. The digital valve unit 100 here comprises 20 on / off digital valves divided into four digital valve groups 10; 10a, 10b, 10c, 10d comprising two digital valve groups 10c, 10d which actively regulate the pressure side (piston head) 20b of the hydraulic cylinder and two digital valve groups 10a which actively regulate the working side of the hydraulic cylinder (piston rod side) 20a. Digital valve assemblies 10b and 10c control the flow of pressurized hydraulic fluid from the feed line vs supply line 7; 71 correspondingly to the working side 20a of the cylinder 20 and the corresponding flow lines 6 to the pressure side 20b of the cylinder 20; 61 and 6; 5 62. The digital valve groups 10d and 10a respectively control the hydraulic fluid outlet flow from the cylinder pressure side 20b and the working side 20a to the tank line 7; 72. A fluid flow pressurized to a certain known pressure enters both the pressure side and the working side 20b, 20a of the hydraulic cylinder 20 for the digital control valve groups 10c, 10b of the same supply line 7; 71 via throttle-10 valve. Supply flow pressure on supply line 7; 71 is effected, for example, by a pump (not shown in the figure). The hydraulic fluid is discharged from the respective digital valve groups 10d and 10a controlling the fluid flow at the pressure and working side of the hydraulic cylinder to the tank line 7; 72, which leads to the fluid storage tank (not shown) through a check valve. Each of the 15 digital valve groups 10 of the digital valve unit 100 has 5 on / off digital valves 1 through which the flow rates in the open position are matched such that the flow rate of the first valve is 1 unit, the second 2 units, the third 4 units, and the fourth 8 units. 16 units, whereby the digital valves 1 of each set of digital valves are capable of providing 31 different combinations of open digital valves 1A, corresponding to 31 flow rate combinations, i.e. different openings of the digital valve set 10. The hydraulic cylinder's 20 pressure and working side 20b, 20a of the respective flow lines 6; 61 and 6, 62 are connected to respective painemit-measuring devices M; M ', M' each comprising a bellows leveler and a pressure gauge. The pressure measuring devices M can be measured in each of the hydraulic cylinder's 20 pressure and working sides 20b, 25, 20a of the flow lines 6; 61 and 6; 62 prevailing fluid pressure in the inlet or outlet flow from or out of the digital valve assembly 10. On the basis of the measured pressure and the feed flow vs feed pressure ps from the supply line 71 to the digital valve groups 10, it is possible to determine the appropriate opening of the digital valve group (= total opening of the digital valves 30 in the group) for each desired loading of the hydraulic cylinder 20. By the load pressure PK of the hydraulic cylinder 20 is meant here the pressure exerted by the hydraulic cylinder 20 (piston 22) on the support lever 3.

Such a digital valve assembly 100 is capable of engaging each side 20 of the piston 22 35 of the hydraulic cylinder 20; 20a, 20b a controlled volume flow V; V2o, V2ob to actively adjust, faster and over a wider flow range than most commercially available slide valves which simultaneously control two different flow channels. Such an active flow rate V20 for the pressure and working side of the hydraulic cylinder 20, realized by digital valve assemblies 10, 20b and 20a; V2ob, V2oa and P20 for fluid pressures; P2ob, P2oa adjustment is much faster than the slide valve 20 with the hydraulic cylinder's working side 20a of control can not be 5 to implement quickly and actively because of the return of the gate valve internal circuit delays and coupled to the return control slide valve implemented slowness. 2B, instead, a feed-forward control of the hydraulic cylinder 2 may be used; 20 a back pressure (= working side pressure) P2oa controlling, as digitaalivent-10 block group 10 in each case in the open position of the digital valves 1 of the valve combination 1A through-flow rate and thus the achievable by such combination of the hydraulic fluid pressure difference between the digital valve group 10 into the liquid supply pressure PS and the digital valves outgoing fluid pressure or flow line pressure P6; P6i or P6; Between P62 can be predicted with good accuracy.

In the exemplary circuit shown in Figures 2B and 2C, fluid flow arrives at digital valve assembly 100 with a throttle shut-off supply line 7; 71 under a certain pressure ps and further passing to the pressure side 20 of the cylinder; 20b or labor 20; 20a through the fluid-flow controlling digital taaliventtiiliryhmän 10; 10c or 10; 10b. The supply side digital valve Chapters 20 to 10; 10c or 10; 10b is an opened digital valve assembly 1A; 120b or 1A; 120a providing the desired volume flow V6; V62 from digital valve assembly 10; 10c to a flow line 6 extending to the pressure side 20b of the cylinder 20; 62 or volume flow V; A flow line 6 from the digital valve assembly 10b to the cylinder side 20a; 61. From each of the digital valve groups 10; 10b, 10c for hydraulic cylinder 2; The volume flow V6 of the fluid exiting along the flow line 6 and the volume flow V20 provided on different sides of the piston 22 of the hydraulic cylinder 20a, 20b, respectively; V2a, V2ob can be accurately predicted from the differential pressure dp for the fluid supply pressure ps through the supply line 71 to the digital valve assembly (10b or 10c) and the corresponding flow line 6 to the pressure or working side of the cylinder 20 after the digital valve assembly 10; 62, 61 the prevailing pressure P6; Between P62, P61 (the pressure Pg of the flow line 6 is P6i in the flow line 6; 61 or P62 in the flow line 6; 35 20b in a flow control digital valve assembly 10b). The pressure difference dp between the flow V6 passed through one of the digital valve groups 10 to the flow line 6 and the input flow vs arrived at the digital valve group i1 16 in turn depends on the opening 1A of this digital valve group 10.

When it is desired to change the loading pressure at the roll nip N, the ratio of the respective volume flows V2ob, V2oa 5 to the pressure side 20b and the working side 20a of the cylinder 20 is changed, respectively changing the ratio P20b, P2o of the fluid pressures 2020, 20a. This controls the loading pressure Pk applied by the cylinder 20 to the support lever 3 in the desired direction. -Men hydraulic actuator's 20 pressure side 20b and working side 20a of incoming volume flow V20a and V20b amounts converted to the corresponding hydraulic fluid to the feed side flow is controlled by the digital-10 liventtiiliryhmien opening 10c or 10b L20B, or by changing the l20a. The feed-side digital taaliventtiiliryhmältä 10; 10c and / or 10; 10b for flow line 6; 62 or 6; 61 outgoing fluid flow V6; V62 or V6; Butter and / or equivalent fluid pressure P6 in said flow lines; P62 or P6; Ρβι leads to a certain volume flow and fluid pressure across the piston 20a and 20b of the piston of the hydraulic cylinder 20. Therefore, the opening 15A or 12A of the digital-15 valve assembly 10c or 10b; conversion of l20a can be made to the pressure side 20b of the hydraulic cylinder 20 and / or to the side 20a of the desired new fluid flow level V20; V2ob and / or V20; V20a and / or a new corresponding pressure and back pressure level P2o; P2ob and / or P20; P2o based on knowing, computationally or empirically, said volume flow or pressure 20 of the flow line 6 on different sides 20a or 20b of cylinder 20; 61 or 6; 62 volume flow V6; V6i or V6; V62 and / or fluid pressure P6 in the flow line; P61 or P6; Based on P62.

When the hydraulic actuator's 20 pressure or working side 20b or 20a leading to the supply side digital valve group 10b or 10c are one or more digital valves 1 in the open position, are respectively the pressure or working side for controlling the outlet flow 25 outlet side digital valve group 10a or lOd all of its digital valves in a closed position (group 10a or lOd opening 1A is 0).

When the desired load pressure Pk of the supporting lever 3 has been reached, the load pressure control enters the steady state by equilibrating the pressure 30 at the pressure and working side 20b and 20a of the hydraulic cylinder 20 P2bT = P20aT · When the hydraulic state V20t, i.e. the volume flow V2ob = V20bT and V2oa = V20aT supplied to the pressure and working side 20b and 20a of the hydraulic cylinder 20, and the pressure equilibrium pressure P2b = P20pa The level of P220aT 35, for example on the basis of the load pressure PK required from the hydraulic cylinder 20 to the support lever 3, can be calculated or estimated by the valve combination 1A of the digital valves 1 which are held open in the digital valve group 17 10. barrier pressure P2ot and volumetric flow ν2οτ · The pressure after digital valve assembly 10 can also be monitored by a pressure gauge M and, if necessary, the control-5 operations checked.

If it is desired to quickly reduce the volume flow of the hydraulic fluid V20T / V20a and the fluid pressure P2ob / P20a on the hydraulic cylinder's 20 pressure / working side 20b / 20a is selected in each case corresponding to the pressure / working side 20b / 20a of the flow lines 62/61 connected PAI-worn monitor M of indicated pressure and the hydraulic pressure / working side of the desired uu With the pressure of -10 den, the open flow digital valves of the digital flow control group 10a or 10d control the discharge flow. The respective input-side digital valve group 10b or 10c digital valves in the supply line 71 to prevent the pressurized fluid flow from passing into the cylinder's 20 pressure or working side 20b or 20a of the flow line 6; 62 or 6; 61. liquid flow passes hyd-15 20 pressure or working side of the hydraulic cylinder 20b or 20a corresponding to the pressure or working side flow line 6; 62 or 6; 61 for the digital valve groups 10d or 10a controlling the outgoing flow (discharge stream). The suitably opened digital valves 1 of these digital valve groups 10a and 10d are adjusted to the tank line 7; 72 a flow rate V6 of said digital valve assemblies along a flow line 61 or 62; 20 V6i or V6; V62 and thus the rate of discharge flow and the magnitude and rate of pressure drop at the pressure or working side 20b or 20a of the cylinder 20.

Fig. 2C is a schematic view of one of the intermediate roll loading arms 3 of the multi-roll calender; 3 'and 3; 3 "" for changing and maintaining the load pressure Pk between the control system 4 and the digital valve unit 100 and, based on the data flows 25, fluid flows to the supporting hydraulic cylindrical pair 20; 20 ', 20 "of the supporting rollers 3; 3' and 3; another hydraulic cylinder because the hydraulic cylinders are similar in construction.

The control unit 42 of the control system 4 receives from the pressure gauges M; M 'and M: M' continuously or at intervals in the flow lines 6 from the digital valve assembly 100 to the piston head (pressure side) 20b of the hydraulic cylinders 20 and the piston rod side (working side) 20a; 62 and 6; 61 at the respective fluid pressures P6; P62, P6; Tämän · This pressure information P6, measured by pressure gauges, and the support levers 3; 3 'and 3; 3 ″ applied load pressure Pk; Pk · and Pk; On a PK 'pe-35 platform, control system 4 may determine a suitable proactive control strategy for changing the load on the telanip or maintaining the steady-state load 18 on the telanip. In the event of a change, the control system 4 decides, based on a pre-programmed proactive control strategy, in which direction the working and pressure fluid pressures P20 of the hydraulic cylinders 20; The ratio of P2oa to Ρ2οί P2ob will be changed, how much and in what time, so that the nip pressure of the roll nip and at the same time the loading pressures Pk on the hydraulic nip pressure of the roller cylinder; Pk ·, Pk- is desired. On the basis of these pressure change parameters, the control unit 42 of the control system 4 calculates each hydraulic cylinder 20 at a given moment; 20 'or 20; Desired fluid flow rates V20 for the piston rod side (working side) 20a and the piston head side (pressure side) 20b; V20a and V20; V20b and possibly also corresponding fluid pressures P20; P2O5 and P2O; P2ob · len-working face 20 and the pressure side of each cylinder volume flows V20; V20a and V20; V2ob corresponds to certain volume flows V6; V6i and V6; V62 plus pressures P6; P6i and P6; Ρό2 in the flow lines 6 leading to the working and pressure side 20a and 20b of the hydraulic cylinder 20; 61 and 6; 62 after the digital valve groups. Ohjausjäqestelmän 4, the control unit 42 supplies a calculator unit 41 15 of information about these new cylinder's 20 working and pressure sides of the flow rates, wherein the las-unit 41 working calculates how each digital valve group 10 aperture 1A to reach desired volumetric flow rates and transmitting a respective adjustment instruction to each digital valve group. For each digital valve group 10; 10a, 10b, 10c, 10d the control instruction to be transmitted is a binary control instruction comprising a hydraulic fluid 20 volume flow control function F (V) or a hydraulic cylinder piston position control function F (X) and including at least which valves 1 in each digital valve group 10; 10a, 10b, 10c, 10d will come and which ones will remain open (digital valve group opening) and for how long.

The above-described hydraulic cylinder's 20 pressure and working sides 25 and changing the pressure applies in particular to a particular paper / board calender-type polymerization start / teaching one event which changes the load pressure is relatively large liquid flows. As calendering continues in steady-state mode, each hydraulic cylinder 20; 20 'and 20; 20 "pressure side of the working face pressure and counter-pressure is kept equal, and thus the hydraulic cylinder on the intermediate roll loading lever 30 in the load pressure SME will be kept at a certain constant level. Because each of the digital valve sets 10 can provide a plurality of discrete volume flows in the flow lines 6; 61 and 6; 62, resulting in an equal number of different volume flow / pressure modes for the pressure and working sides of the hydraulic cylinders 20, the same digital valve group can provide both steady-state 35 incremental volume flow and pressure changes as well as high pressure and volume volumes changes.

19

The above-described control method is known in advance for the respective digital valve group 10 of a particular aperture 1A that is achieved with the combination of open valves, the volume flow of the stream lines 6 and the hydraulic cylinder's working or pressure side need to perform pressure adjustment paluukytketysti. In this case, the simple-5 introduces to the pressure and working side of each hydraulic cylinder 20 the need for the measurement signals required in the fluid flow and pressure control system 4, and eliminates the double annotation required for analogue valves.

Synchronization of Hydraulic Actuators 10 Synchronization of two or more hydraulic actuators 2 has traditionally been accomplished in the papermaking industry either by using flow distributors, by switching actuators to Saija, or by controlling each actuator individually by means of position or flow-controlled servo / proportional valves.

If the synchronization is carried out on the flow distributors, the accuracy of the synchronization will depend on the manufacturing tolerances of the components of the said flow accumulators. If the hydraulic actuators 2 are again located in Saija, the problem is a failure; if the actuators go out of sync, they must be serviced, which usually requires external intervention. The problem with actuator-specific control of control circuits with servo / proportional control valves is the high cost of such circuits. In addition, the pressure drop of such control valves is considerable, and special positioning control and control feedback are required to accomplish synchronization.

Such synchronization of the operation of the two hydraulic actuators can be accomplished in a conventional manner by means of digital valve units 100 both by connecting the hydraulic actuators 2 to the Saija and by using flow dividers to divide the flow from the same digital valve group to different hydraulic actuators. 2B and 2C, the same digital valve assemblies 10 of digital valve unit 100 are used to synchronously control two hydraulic actuators 2 at each end of the roll; 20 'and 2; 20 ". The outputs from each digit-30 livestock valve group are branched at a convenient location for the various hydraulic actuators as shown in Figure 2B.

However, the synchronization of the hydraulic actuators 2 can be advantageously accomplished by digital valve technology using one or more digital valve units 100 per actuator: each actuator 2 is individually controlled by its own digital valve unit and the operation of these digital valve units is synchronized at the control signal level. Each of the digital valve groups 100 of the digital valve unit is provided with an adjusting instruction a time-bound flow reference F (V) or a position control function F (X) (cf. Fig. 2C) and thereafter the digital valve group accurately adjusts the 5 outflow to / from the actuator. Thus, the digital valve group precisely controls the speed of the hydraulic actuator. The accuracy of the adjustment made by the digital valve unit 100 is due to the fact that a) the operation of the digital valve group 10 of each digital valve unit can be controlled accurately by the feedback control mode, the nominal volume flow of each valve, as shown above in connection with the description of Figures IA and IB. Even a very small increase in the number of digital on / off valves significantly improves the control accuracy.

2D schematically illustrates two separate but functionally interconnected digital valve groups 100; 100 'and 100; 100 ”realized control of the operation of two parallel hydraulic actuators 2 connected in parallel. The hydraulic actuators 2 are hydraulic cylinders 20 which control, for example, the position of the swing levers at the ends of the same roll in the same manner as shown in Figures 2B and 2C. Both hydraulic cylinders 20; 20'and 20; 20 ”controlled by its own digital valve group of 100; 100 'and 100; 100 ". Each digital valve unit 100 'or 100' has four digital valve groups 10; 10a, 10b, 10c, lOd. The structure and function of the digital valve units 100 'and 100' and the digital valve assemblies 10 contained therein are identical with respect to each other. the same structural parts of digital valve units are designated by the same reference numerals. Each digital valve unit 100; The digital valve assemblies 10a, 10b, 10c, 10d contained in 100 ', 100' always control the flow to or from the pressure or working side of one of the hydraulic actuators 20 'or 20'. Each digital valve group 10 comprises n pieces of 30 digital valves, Figure 2D shows only each digital valve group 10, the first and last digital valves 1. The reference numerals 10a and 10b, the marked digital valve groups provides for each hydraulic actuator's pressure side (piston head side) 20b by way of a flow line 6; 62. Reference numerals 10c and lOd marked digital valve groups provides in turn 35 in each hydraulic actuator's 20 working side (piston rod side) 20a by way of a flow line 6; 61. From feed line 7; 71 incoming, pressurized hydraulic fluid flow vs; vs> it vs; vs-> thus passes through the valve 21 to the digital valve unit 100; 100 'or 100; 100 "and further through each of the digital valve units 100 'or 100" through the digital valve assemblies 10b or 10c to the pressure or working side 20b or 20a of the respective hydraulic cylinder 20 (respectively). Hyd raul fluid flow vt; vt- or vt; vt 'exits each hydraulic cylinder 20; 20 'or 2; 20 "5 from the pressure or working side 20b or 20a via the flow line 62 or 61 to the digital valve groups 10a or 10d and further to the tank line 7; 72. Providing a desired flow rate of each hydraulic cylinder 20; 20 'or 20; The 20 "pressure or working side 20b or 20a is performed analogously to the system shown in Figs. 2B and 2C, however, taking into account that each hydraulic cylinder 20; 20 '10 or 20; 20 ”has its own digital valve unit 100 controlling it; 100 'or 100; 100 ". Hydraulic cylinders 20 'and 20' from feed line 7; 71 incoming feed streams vs; vs and vs; vs-> or hydraulic cylinders 20 'and 20' for tank line 7; 72 outgoing output currents vt; vt · and vt; vt ”are in no way connected before entering the common feed line 7; 71 or tank line 7; 72. The synchronization between the operation of the digital-15 livestock valve units 100 'and 100' and the hydraulic actuators 20 is thus controlled by a control system (not shown in the figure) which gives them control instructions. Here, the volume flow control of each of the hydraulic actuators 20 'and 20 "at a given time interval is accomplished by a feed-forward control mode by providing each digital valve unit 100' or 20 100" with the desired volume flow reference F (V) 'and F (V) " V) 'and F (V)' are identical. Equally, digital positioning units could only be given position control F (X) with respect to the piston of the hydraulic actuator 20, since the pressures of the position of the piston of the hydraulic actuator and the working and pressure side of the hydraulic actuator are known. This is because the pressures present on the working and pressure sides 20a, 20b of the hydraulic actuator 20 are directly proportional to the fluid pressures present in the flow lines 61 and 62 and the volume flow through the digital valve groups 10 of the digital valve unit 100 description. Digital valve unit-30 in ropes 100; 100 ', 100 "does not exhibit major time delays, but the execution of a specific volume or positioning instruction F (V), F (x) is accurate, fast and of excellent reproducibility, with corresponding hydraulic actuators 20', 20 'coupled to these digital valve units 100', 100 '. '' work synchronously.

In practice, synchronization of the operating and pressure sides of two different hydraulic actuators with ana-35 logic valves is practically impossible due to differences in valve manufacturing tolerances, high cost, and control problems with small valve openings. Instead, by using digital valve units, such a 4-way connection of two hydraulic actuators 22, which controls both incoming and outgoing flows to both the working and pressure sides 20a and 20b of the hydraulic cylinder, can be easily accomplished with its own controlled hydraulic group 10a, 10b, 10c, 10d.

Quick opening of calender roll nip and quick change of roll nip load

When changing the board / paper type or joining the board / paper web to another cardboard / paper web, it would be preferable to only lighten the calender roll nipples as the seam between two successive fiber webs passes through the calender roll nipples. Such a need has arisen in the calenders placed after the on-machine coating machines and in the off-machine calendars of the flying seam.

If, on the other hand, the calender roll nipple has to be completely opened, for example, in a web home situation, it would be advantageous if the torque of the rolls (rotation speed of the rolls) need not be changed when opening and closing the roll nip.

Servo and proportional valves (gate valves) are currently used to control the pressure of the hydraulic actuators acting on the support levers at the ends of the intermediate rolls or from the inside of the roll to the roll shell and / or adjusting the loading cylinder that raises or lowers the bottom or top of the roll. However, the slide valves operate only accurately within a limited volume flow / pressure range and have a relatively large internal delay in control; if the loading pressure of the hyd-20 roller cylinder needs to be changed rapidly while the volume flow to the working and pressure side of the hydraulic cylinder changes significantly, problems with the delay of the valve control of the spool valve and the rapid loss of control In practice, the slide valves 25 are not capable of rapidly relieving and returning the calender roll nipple load to the pre-change load level, nor can the instantaneous roll nip open and close quickly while the calender running speed remains unchanged.

The invention is intended to eliminate the disadvantages of the prior art.

Accordingly, it is an object of the invention to provide an apparatus and method for temporarily relieving nip load on a calender roll nip and restoring the original nip load such that a roll-nip load-lightening-reload cycle is produced as quickly as possible while sufficiently accurate with respect to variation in roll load.

23

It is also an object of the invention to provide rapid opening and reclosing of the roll nip while maintaining the running speed of the calender.

The apparatus according to an embodiment of the invention and the method of relieving and unloading the roll nip utilized therein achieve the above objectives.

This embodiment of the invention is based on the fact that the hydraulic actuators such as the hydraulic cylinders 20 acting on the levers 3 at the ends of the intermediate rolls 5 or from the inside of the roll to the roll casing and / or the loading cylinder directly pressurizing the calender top or bottom the telenip N loading pressure relief pulse followed by the telo lanip N loading pressure return pulse. The position of the seam at the fiber web incoming to the multi-roll calender is identified and its arrival time on each roll nip in the calender is estimated or calculated. In the successive roll nipples of the multi-roll calender 500, the roll nip lightening pulse and the return pulse are performed in a suitably synchronized manner, at a 15 H seam between two fiber webs; Ws for controlled passage through the roll rolls of the multi-roll calender.

In order to provide a relief pulse, the loading pressure at the roll nip N is reduced by momentarily decreasing the fluid volume flow to the pressure side (piston side) of the hydraulic cylinder 20 with the corresponding digital valve group 10 relative to the equilibrium fluid flow at the operating side of the hydraulic cylinder 20. When the loading pressure exerted by the loading lever 3 on the cylinder 20 has been sufficiently reduced, the ratio of the pressures on the working and pressure sides of the hydraulic cylinder 20 is restored. By temporarily increasing the fluid flow to the pressure side of the hydraulic actuator over a period of time relative to the steady state fluid volume flow, the digital valves (load pulse) of a suitable digital valve assembly 10 return the load applied by the hydraulic actuator to the pressure pulse. Once the pressure load has been returned to the pre-change level may be a hydraulic actuator such as a hydraulic cylinder's 20 working and pressure side pressure.

Another embodiment of the invention, in turn, is based on providing stepped accelerated opening pulses to the roller loading members connected to the hydraulic actuators (e.g., hydraulic cylinders) by means of digital valve units coupled to the hydraulic actuators. The load on the roller loading members is reduced by a feed-in control mode by varying the volume flow (and hence the pressure therein) of the hydraulics to a certain predetermined volume flow profile. This embodiment of the invention may be used, for example, during a fiber web break during calendering; the point of breaking of the fibrous web by the incoming fibrous web is identified and its time of arrival at the calender roll nip is estimated and calculated. When the fiber web break point reaches the roll nip, the roll nip is quickly opened by the method of the invention and then closed in a conventional manner.

These embodiments of the invention are illustrated below by way of exemplary embodiments and related Figures 3A and 3B.

Figure 3A schematically illustrates the generation of a relief and return pulse to a roll roll nip of a multi roll calender when a defective point on a fibrous web arrives at said roll nipple.

Figure 3B illustrates one roll nip of a multi-roll calender that receives interference on a fibrous web.

Figures 3C-3E show the changes in volume flow and fluid pressure during the relief and return pulse of Figure 3A in the hydraulic cylinder loading the roll support lever.

Figure 3F shows one roll nip of a multi-roll calender that receives a web break.

3G, in turn, illustrates a quick opening of a roll roll of a multi-roll calender by the method of the invention when a web break on a fibrous web enters said roll nip.

Figure 3H shows the changes in volume flow and fluid pressure during the opening of the roll nip of Figure 3E in the hydraulic cylinder loading the roll support lever.

3A to 3E illustrate an exemplary application of the relief and return pulse to the roll nip and the quick opening of the roll nip of Fig. 3F -3H as applied to the multi-roll calender 500 of Fig. 2A with an intermediate roll 5; 5a, the control lever system 4 of the support lever 3 and the digital valve unit 100 controlling the support lever are, for example, according to Figure 2D. Also, calender 500 te-30 shells lowest roll 5; 5b for lifting and uppermost roll 5; The control of the load cylinders weighing 5b may be implemented at least in part by a similar digital valve unit 100 and a control system 4 thereof.

25

Figures 3A-3E illustrate the creation by a digital valve unit 100 of a controlled relief and return pulse on a hydraulic cylinder 20 acting on a support lever at the end of a multi-roll calender intermediate roll when a failure point H passes through the roll nip; 5 Ws. Through the relief and return pulse, the load pressure Kp applied to the support lever by the piston 22 of the hydraulic cylinder 20 is changed as the failure point passes through the roll nip. The figures illustrate the change of the loading pressure on only one end of the intermediate roll by a relief and return pulse, since 10 identical synchronized relief and return pulses are applied to the other end of the intermediate roll by a control similar to that shown in Figures 2B-2D.

Figure 3B shows two overlapping rolls 5 with a roll nip N between them. The rolls are, for example, two rolls of the multi-roll calender of Figure 2A. A calenderable fiber web W passes through the roll nip. The figure illustrates a situation where two different fiber webs W are just entering N roll 15; W 1 and W; W2 seam between Ws.

Fig. 3A shows above the seam H of the fibrous web W of Fig. 3B; Ws upon arrival at the roll nip, the roll nipple relief and return pulse. The figure shows the changes in the hydraulic fluid volume flow 20 V20b during the roll nipple relief and return pulse to the pressure side (piston head) 20b of the hydraulic cylinder 20 over a given time t and lower during the same time t to the load lever pressure Kp. This embodiment of the invention relies on the feedback control of the load pressure Kp implemented by the digital valve unit 100 during both the light-25 nip pulse of the roll nip N and the load pressure return pulse of the roll nip N.

Figures 3C to 3F show the movements of the hydraulic cylinder piston 22 during the roll nipple relief and return pulse to control changes in the load pressure Kp of the roll support lever on the roll nip. Figures 3B-3D further show the hydraulic fluid flows V2oa and V2ob supplied to different sides of the piston 22 of the hydraulic cylinder 20 from piston 20a 20b and 20b, and the fluid pressure P2oa caused by the hydraulic fluid flow, P20b. 2D, comprising four digital valve groups 10a, 10b, 10c, 10d, two of which control the flow of fluid to the piston head side 20b of the hydraulic cylinder and the other two to the piston rod side 20a.

26

Fig. 3F shows two overlapping rolls 5 with a roll nip N between them. The rolls are, for example, two rolls of a multi-roll calender according to Fig. 2A. A calenderable fibrous web W passes through the telecommunication nipples.

Fig. 3G, in turn, shows a quick opening of the roll nip N by the method according to the invention, of the web break H of Fig. 3F; Wk on arrival at roll nipple. The top view shows the change in the volume flow rate V20a of the fluid supplied to the pressure side 20b of the hydraulic cylinder 20 at a given time t and below schematically the change in the vertical position of the roll 5 (e.g., between two rolls N Alem-10 man in the vertical). When Fig. 3E shows the change of the position of the roll 5 in the calender roll nip N, the change in the relative position of the piston 22 loading the roll through the carrier lever 3 under a loading pressure Kp is similar in the longitudinal direction of the hydraulic cylinder 20. The changes in the load pressure Kp of the piston 22 and the associated roll support lever 15 at opening of the roll nip are illustrated in Figure 3H.

When the volume flow rate V2o and the pressure P2o to the fluid supplied to the hydraulic cylinder 20 are controlled by a digital valve unit 100 including a plurality of digital valve assemblies 10, as described in connection with the 10 volumetric flow rate. The volume flow is known from the opening 1A of each of the digital valve groups 10 and the pressure difference to the fluid pressure ps in the supply line entering the digital valve group or from the tank line 7 leaving this digital valve group; 72 between the prevailing fluid pressure pt and the fluid pressure P6 flowing in the flow line 6 to the hydraulic cylinder 20.

For example, when a supply flow Vs arrives to the supply line 7 of the digital valve assembly 10b of the digital valve assembly 100 shown in FIG. 3C-3F; 71, with its average pressure exerted on the walls of the supply line by ps, from said digital valve assembly 10b to the pressure side 20b of the hydraulic cylinder 20 is the flow-30 line 6; 62 is the magnitude of the outflow volume V62 to the loading cylinder 20 based on the fluid pressure P62 in the flow line 62 and the respective opening of the digital valve assembly 10b. The fluid pressure P62 is accurately predicted by the size of the opening of the digital valve assembly 10b, i.e. the total flow opening formed by the digital valves that are open, i.e. the amount of throttle produced by the digital valve assembly. Since the digital valve assembly 100 from the digital valve assembly 10b to the flow line 6; Output volume flow V62 62 (and further to hydraulic cylinder pressure side 20b) and pressure P62 in flow line 62 are accurately predictable, fluid pressure P20b formed on piston head side 20b of hydraulic cylinder 20, and fluid flow V2ob are predictable with no feedback control. Likewise, the fluid pressure P2o and the fluid flow V20a on the piston rod side 20a and the volume flow rate V0i and the liquid pressure P0i on the flow line 6 are also predictably reliable; 61 when the opening 1A of the digital valve assembly 10c which controls the flow to the flow line 6 is known; 61 from feed line 7; 71 (cf. also the description of Figure 2D).

To now provide a rapid roll-nip load relief pulse and a return pulse of the intermediate roll bearing load pressure Kp of the hydraulic cylinder 20, the hydraulic cylinder 20 connected to the digital valve unit 100 by intermediate flow lines 6, is momentarily reduced to 20 V2oa.

Preferably, the relief and return pulse administration is accomplished by first reducing the volume flow to the piston head 20b of the hydraulic cylinder by a certain amount, and then returning the volume flow to the piston head 20b after a certain time t to its former level. The load return pulse is then applied by first increasing the volume flow to the piston head 20b of the hydraulic cylinder by a certain amount, and then returning the volume flow to the side of the piston head 20b after a certain time t to its former level. As a result of this operation, the loading pressure Kp on the roll nip acting on the support lever of the piston 22 of the hydraulic cylinder is reduced from the pressure level A to the pressure level B during the time t1, as shown in FIG.

The volume flow to the piston head side 20b of the hydraulic cylinder is subtracted by the digital valve group (s) of the digital valve assembly 100 that control the volume flow V6; 62 and thus also fluid pressure P6; 62 in a flow line 6 to the piston head of the hydraulic cylinder 20; 62. Adjustment of the volume flow V62 is performed, as previously shown in connection with Figs. 2B and 2D, to select a 30-pin suitable opening of the digital valve assembly 10b that implements the reduced volume flow V62. The opening of the digital group 10b is then restored to the same state as before the opening change. This operation first reduces the flow line 6 to the piston head side 20b of the loading cylinder; 62, and then, after a short period of time (calculated from the start of the flow change), return the piston-side volume flow to its former level (pulse 1 in Fig. 3A) to relieve pressures on the hydraulic cylinder pressures and working sides 20; 20b, 20a. The effect of the lightening pulse on the position of the piston 22 of the hydraulic cylinder and the loading pressure Kp caused by the piston support lever are illustrated by way of example in Figures 3D and 3E. Fig. 3C shows the situation just prior to the application of the lightening pulse, for example in the state-5 of Fig. 3B, during the calendering of the fiber web, in steady-state equilibrium. In equilibrium, the digital group is given a control command F (V) to maintain equilibrium; F (VT), wherein the opening of the digital valve assembly 10b is 1A; l2obT and digital valve assembly 10c have an opening of 1A; l20aT · With these openings of digital valve groups 10b and 10c, digital balance groups 10b and 10c direct both the piston head side 20b of the hydraulic cylinder 20 and the piston rod side 20a to a steady state volume flow V2obT and V2obT and V2obT side 20b and piston rod side 20a. Thereafter, the digital group 100 is given an adjustment instruction F (V) for the lightening pulse (pulse 1); F (Vi). in accordance with 15 Säätöohj C. piston rod side of the volume flow - and pressure is kept the same, or at V2oaT, P20aT, but the piston head side 20b of the volume flow is calculated from the first steady-state volume flow V20bT to V20bi, which corresponds to a reduced fluid pressure P20bi and after tl after this time period is returned to the volumetric flow and pressure equilibrium V20bT, P20bT · Due to the lightening pulse, the piston 22 moves so that the loading pressure Kp caused by its support lever is reduced.

After a suitable time t2, calculated from the end of the lightening pulse (pulse 1), a return pulse (pulse 2) F (V) of 20 return pulses (pulse 2) is given to the digital valve unit as an adjustment instruction (load Kp); F (V2), by temporarily adding the volume flow to the piston side 20b of the hydraulic cylinder 20 to the pressure side relative to the flow to the working side 20a of the cylinder (piston rod side). This is preferably accomplished by first suitably changing the opening of the digital valve group 10b to control the flow to the piston 20b from opening l20bT to opening l2ob2, whereby the volume flow through the flow line 62 to back to the equilibrium volume flow V2obT (pulse 2 in Fig. 3A) at the pressure and working side of the cylinder, the same as returning to the equilibrium volume flow V2obT (pulse 2 in Fig. 3A). During the return pulse, the volume flow rate and fluid pressure to the hydraulic cylinder side 20a are generally kept constant 29 V20aT, P20aT · As a result of this operation, the loading pressure Kp applied to the piston and providing a recovery pulse to the prevailing level of ta-5.

If the calender is a multi-roll calender 500 having a certain number of roll nipples N (e.g., a calender similar to Figure 2A), the lightening and return loading pulses of successive roll nipples are synchronized such that the seam between two fiber webs passes through all calendering rollers.

The exact effect of the relief and return loading pulse delivered by the digital valve unit 100 and the delay of the action on the hydraulic cylinders 20 acting on the levers 3 at the ends of each intermediate roll may vary slightly depending on the pressure losses in the hoses (in the lower roll and in the upper roll, the cylinder 20 is a loading cylinder directly affecting the vertical position of the roll). Here, the synchronization of the relief and loading pulses to the respective travel speeds of the calender 500 can be performed, for example, by measuring the effect of the relief and return pulses delivered by the digital valve unit 100 on the support pressure and further the loading pressure of the rolls.

When, on the other hand, the hydraulic cylinder 20 controlled by the digital valve unit is intended to rapidly open the roll nip N between two rolls, for example, the web break H of Fig. 3F; As wk passes through the roll nip, rapid reduction of the roll nip nip pressure 25 is performed by changing the ratio of the volume flows V20b, V20a arriving to the pressure and working sides 20b, 20a of the hydraulic rollers 20 which press the roll support levers within the roll nip. Figure 3 G illustrates a supporting lever pressurizing hydraulic cylinder's piston head side fluid supplied to the hydraulic cylinder the volume flow profile of the flow volume of the working side remains essentially unchanged. In this way, the loading effect of the member acting on the hydraulic cylinder, acting on the roll position N in the roll nip N, is rapidly reduced (e.g., the head . When the fiber web 35 disruption point Wk (web break) enters the roll nip, the vertical roll position is initially changed by rapid initial acceleration (Figure 1, 3G) by rapidly reducing the fluid pressure at the piston head side of the hydraulic cylinder relative to the fluid pressure at the piston rod side. To change the ratio of fluid pressures, the volume flow (and fluid-5 pressure) passing through the digital valve array 10b to the pressure side 20b of the cylinder 20b is reduced from the equilibrium volume flow rate V20bT and reduction of the load pressure Kp to Kpi. The volume flow is reduced by limiting the size of the flow opening Ia formed by the digital valve assembly 10b, by selecting a suitable one. opening 1A of digital valve assembly 10c; 12ομ> providing said lower flowrate V20bi · Simultaneously, the flowrate V20a to the piston rod side 20a of the cylinder 20 may be momentarily increased from the equilibrium flowrate V2oaT to the new larger flowrate V20ai to the fluid pressure P20a incrementally P2obT (P2oai> P2obi) · The loading action of the piston 22 on the roll pressure member (here, the intermediate roll support lever) of the piston N decreases and the vertical position of the roll changes from position D to position E after this initial acceleration of the piston 20b 20a, the difference between the prevailing pressures P20b and P20a is reduced by incrementally increasing the volume of hydraulic fluid supplied to the piston side 20b, as shown in the upper figure of Figure 3G. the loading effect Kp of the hydraulic cylinder 20 on the pressurizing member of the roll and further on the roll 25 is further reduced, but slower and stepwise, and at the same time the vertical position of the roll changes according to Fig. 3. The pressure difference between the liquid pressures P2ob and P2oa on the piston head side 20b of the hydraulic cylinder 20 and on the piston rod side 20a is gradually offset by increasing the volume flow V20b to the piston head side 20b and stopping the fluid pressures on the piston side 20b of the hydraulic cylinder 20 and on the arm side 20a are the same, so that the ratio of volume flows to the piston side and to the arm side is the same as before the roll nip opening. In the remaining equilibrium state, the liquid pressures P2obTn and 35 P2oaTn on the piston side 20b and the arm side 20a of the hydraulic cylinder 20 are lower than the equilibrium pressures P20bT and P20aT at the beginning of the opening of the roll nip N · 31

The N-quick opening of the telanip is controlled directly by the volume flow through the various digital valve unit groups 10 of the digital valve unit according to a pre-formed volume flow profile, and the quick-opening tuning is performed on each roll nip of the calender. Changes in the profile of the volume flows to the different sides of the load cylinder 5 can be made, if necessary, based on verifiable measurements.

The above changes in the position of the hydraulic cylinder piston 22 and the load pressure Kp during the quick release are further illustrated in more detail in Figure 3H. Fig. 3H is a schematic view of another hydraulic cylinder 20 for pressurizing the support lever at the end of the roll of the multi-roll calender, the operation of which is controlled by a similar digital valve controlled system as previously described in Figs. 2D and 3B-3D. Prior to quick opening, for example, the steady-state (steady-state) during continuous calendering has a steady-state loading pressure, the steady-state loading pressure KpT. Liquid pressure P20aT on the piston head side of the hydraulic cylinder 15 is achieved by the volume flow V20aT · Similarly, on the pressure side of the hydraulic cylinder, i.e. in the figure, F (VT) which may be feedback. When changing the verbal position of the roll 20 at rapid initial acceleration (step 1E in Figure 3E), the digital valve unit is provided with an adjustment instruction F (V); F (V0, by which the digital valve unit subtracts the volume flow (and fluid pressure) through the digital valve assembly 10b into the pressure side 20b of the cylinder 20b from the equilibrium volume flow rate V20bT and the corresponding liquid pressure P2obT to a predetermined volume flow rate which achieves a rapid reduction of the loading pressure Kp of the hydraulic cylinder from the equilibrium loading pressure KpT to the lower loading pressure Kp. At the same time, 3E, followed by the stepwise hydraulic state shown in Figure 3E. smoothing the pressure difference between the fluid pressures P20b and P20a on the piston head side 20b of the cylinder 20 and the piston rod side 20a. To accomplish this to-35, the digital valve assembly is provided with Saija control instructions (F (V); F (V2), F (V3) .. .F (Vn) to increase the volume flow V20b to the piston head side 20b and possibly simultaneously reduce the piston rod side 20a 32). the flow volume V2oa to be conveyed as the load pressure Kp decreases stepwise Kp2, Kp3..Kpn At the end of the opening of the roll nip N, the steady-state loading pressure is Kpn, which is significantly lower than the pre-opening loading pressure KpT.

In one variation of the invention, the quick opening of the roll nip is accomplished by a so-called hybrid control, in which large changes in the flow volume of the fluid opening in the loading cylinder (e.g., step A of Fig. 3E) are rapidly accomplished by a digital control array. Slower continuous roller roller opening with smaller volume flow changes across the loading cylinder can then be accomplished with conventional slide valves using a feedback control mode.

Vibration suppression

The paper machine generates resonant oscillations at several points due to moving machine parts, which can damage the paper machine equipment and reduce the speed of the pa-15 game machine.

In multi-roll calendars, at certain rotation frequencies of the rolls, a so-called barring phenomenon may occur, in which resonant oscillations occur in successive rolls of the calender. The Barring phenomenon is often due to the irregularities on the fibrous web in the MD direction. The barring effect damages the coating of the polymer coated rolls 20.

Film transfer technology is one of the most commonly used methods for coating, surface sizing and pigmenting paper and board today. In the film transfer technique, a film is formed on the roll by an applicator and the film is transferred to the surface of the fibrous web in a roll nip between the roll and its counter roll. Particularly at high fiber web travel speeds, in the film transfer technology, surface irregularities in the roll may cause resonance vibrations in the roll nip between the roll and the application bar, causing fogging of the coating or surface adhesive and / or uneven spreading of the film onto the roll.

For winding a paper web onto a storage roller, a commonly used winding apparatus 30 is used to transfer the paper web to the storage roller via a roller nip between the storage roller and the front roller, while simultaneously supporting the storage roller from below. If the paper roll feed from the front roller to the storage roller causes irregularities in the roller roll of the storage roller, which easily causes additional malfunctions in the paper feed and roller when the end roll and / or endless metal tape supporting the stock roll begins to resonate with the paper roll roller.

In all these cases, the resonant vibration can be prevented by the apparatus of the invention and the method used therein.

The method according to the invention is then based on identifying the location of the vibration interfering factor H on the surface of the roll or on the fibrous web entering the roll nip, for example by pressure measurement connected to the roll nip and estimating or calculating the disturbance time on the roll. Thereafter, when the interfering point enters the roll nip, the pressure in the nip is momentarily reduced by means of proactive feedback. The pressure reduction occurs by reducing the support / pressure effect of the carrier / pressurizing means supporting the roll and / or its counter-roll via a hydraulic actuator coupled to one or more digital valve groups that control the flow of volume to the hydraulic actuator. The momentary relief of load exerted by the hydraulic actuator 15 coupled to the digital valve assembly 100 on the support means 3 and the return of the load on the roll nip N occurs, for example, in a similar manner to that described previously in FIG.

Compensation for Deformation of the Long Nip Calender Belt One type of calender currently used for soft calendering of a fibrous web is a so-called shoe calender, wherein the calenderable fibrous web is led to a long nip consisting of a hard surface backing roll (generally heated If the endless strap or the surface of the shoe roll used on the shoe roll used in the shoe calender is somewhat thinner than the other structure, the thickness of the material web W may be calendered in the long nip each time the thinner end of the endless strap or counter roll. Typically, a shoe calender will wear a endless belt (e.g., a fabric reinforced polyurethane belt) that rotates over the shoe element of the shoe roll.

The object of the invention is to eliminate the above drawbacks observed with the long nip calender.

The uneven calendering of the web of material W can be prevented by the method of the invention and the apparatus used therein. In this method, hydraulic actuators such as hydraulic cylinders that load the shoe element of the shoe fish are connected to one or more digital valve groups. The method is based on the fact that each time the thinner end of the shoe roll or its thinner roll rolls into the long nip, the load on the hydraulic cylinders pressurizing the shoe element is lightened and the load on the hydraulic cylinders pressurizing the thinned shoe element 5 is restored.

The invention will be described in more detail with reference to Figures 4A and 4B.

Figure 4A is a schematic view of the shoe calender viewed directly from the end.

Figure 4B is an enlarged view of the long nip region of Figure 4A.

Figure 4A schematically illustrates a typical shoe calender 800 with no lubrication stroke removed. 4B, in turn, shows an endless belt 8a of a long-nip region N of a shoe roll 8 with a thinned point of a fibrous web W such as a paper web.

The shoe roll 8 consists of a loadable shoe element 8b, a hydraulic actuator 2 for loading the shoe element 8 on the roll nip N 15 between the shoe roll 8 and the opposite roll 80, an endless belt 8a rotating over the shoe element, and The hydraulic actuators 2 shown in the figures consist of two parallel rows of hydraulic cylinders 200; 200 'and 200; 200 ”, with rows running from shoe element to end in machine direction (MD direction) in 20 perpendicular directions (CD direction). Each row of hydraulic cylinders 200; 200 'and 200; 200 ”controlled by its own digital valve unit 100; 100 'or 100; 100 ". The operation of the digital valve units 100 is synchronized with the control system 4. The structure of the digital valve units 100 'and 100', the operation control of each hydraulic cylinder row 200 'and 200' with these digital valve units and the synchronization of the operation .

The shoe calender 800 has a heated thermo roll 80 for use in soft calendering of the material web as the counter roll 80 of the shoe roll 8, whereby the long nip N of the shoe calender 800 is formed between the shoe element 8b and the endless belt 8a rotating over the shoe element.

Detection of deformation of the endless belt 8a can be accomplished by continuously measuring on-line the loading pressure P1 created by the hydraulic cylinders 200 loading the shoe element 8b and the surface pressure P2 of the endless belt on the long nip N. For example, method. By creating a differential pressure dp = P1-P2 between the roll pressure nip load pressure P1 and the endless belt surface pressure P2, a reduction of the endless belt 8a can be detected and the thinned spot located. Thereafter, the control system 4 generates a suitable proactive adjustment instruction F for relieving nip pressure via the digital valve assembly 100 each time the thinned H of the endless belt 8a is reduced; Ht is calculated at the incoming roll nip N. The control system 4 then takes into account at least the speed of rotation of the endless belt 8a, the length N of the long nip in the machine direction, and the thickness and area of the thinned point Ht of the endless belt when calculating the duration and start time of the lightening pulse. The nip pressure is lightened and again restored by providing the shoe element 8b with hydraulic actuators 2, such as hydraulic cylinders 15, connected to a digital valve group / groups 100, suitably timed and of the correct duration in the lightening pulse and . The lightening pulse and the load restoring pulse first reduce the loading pressure of the hydraulic cylinders 200 to the shoe element 8b, and at the same time re-load the nip loading pressure on the roll nip N and after a suitable period of time from the start of the lightening pulse 20.

Due to delays in the hydraulic actuators 200 (cf. e.g. FIG. 3A, bottom view), measures to reduce nip pressure are initiated by the digital valve assemblies shortly before the thinned H of the endless belt 8a; Ht rotates to 25 long nip Ns. The lightening pulse of the hydraulic actuators 200 is provided by changing (reducing) the piston side of the hydraulic actuators from the digital valve groups 100; 100 'or 100; 3A to 3E, and after a short time, returning the flow rates to the pre-migration level by closing and opening the appropriate valves of the digital valve unit 100 digital valve assembly. The flow relief pulse provided by the valves of the digital valve assembly results in a reduction in the pressure exerted by the hydraulic cylinders on the piston shoe element 8b and further on the endless belt 8a pivoting on the elongated N region of the shoe element; however, since the portion Ht of the endless belt 8a applied to the N-region of the longitudinal nip is thinned, the loading pressure exerted by the endless belt 8a on the fiber web W, on the other hand, remains at its former level. Shortly before the thinned edge H of the thinned portion H of the endless belt 8a leaves the region of the long-nip N, steps are taken to restore the load pressure of the shoe element 8b by digital valve units 100. To this end, the fluid flow to the piston side the ratio is restored by a suitable opening of the digital valve unit digital set as described in the description of Fig. 3A (and at the same time the fluid pressures on each side of the piston of each hydraulic cylinder are restored to the same steady-state fluid pressures). Due to the load return pulse provided by the digital valve units 100, the loading pressure of the hydraulic actuators 200 10 on the shoe element 8b in the long-nip area N is restored to the pre-lightening pulse steady-state level.

For the above described reduction of load and recovery of load on the long-nip N rotating endless belt 8a (or, in fact, on the shoe element 8b underneath the endless belt 8a and on the load 15), or the rotational speed of the endless belt 8a, the length N of the long nip in the machine direction and the length of the thinned point Ht of the endless belt 8a in the machine direction. In addition, information is provided to the steering rig 4 on the loading pressure exerted by the hydraulic actuators 200 on the shoe element 8b and changes in the loading profile of the endless belt 8a at the long nip. The length of the thinned point Ht of the endless belt 8a and the thickness of the thinned point relative to the rest of the endless belt, as well as the length of the thinned point in the longitudinal N longitudinal direction (machine direction), are obtained from pressure measurements. In the method of the invention, the amount of pressure reduction P1 applied by the hydraulic actuators 200 to the piston shoe element 8b depends on the degree of thinning of the endless belt relative to the thickness of the other, unthinned portion of the endless belt. Since changes in the hydraulic fluid flow rates on the pressure and working side of the hydraulic actuators 200 result in a certain change in the compression force exerted by the piston on the hydraulic actuators 200 to the shoe element 8b and further to the endless belt 8a, As previously stated, the flow rate through each digital valve assembly depends on the opening 1A of the digital valve assembly 37, i.e., the total area of the openings in the digital valve openings and the difference in pressure between the related description). The pressure difference over the opening 1A of a given digital valve assembly is obtained by measurement or otherwise well predictable. Hereby, the control system 4 is capable of generating a fast feedback feedback control over a certain period of time according to a certain control profile (cf. Fig. 3A) to reduce and restore the load on the endless belt 8a at the fault location H; Ht passes through the longitudinal nip N, whereby the control system 4 selects, on the basis of the desired flow rates of the hydraulic cylinders 200, the flow of the hydraulic elements to be controlled by the digital valve units 100; 100 'or 100; 100 ”digital valve groups that provide load reduction and reset pulses in accordance with the control instructions and then select the currently open digital valves from these digital valve groups based on the magnitude of the desired change. As previously mentioned, the time between the lightening and resetting pulses of the ken-15 hand element 8b and at the same time the endless belt 8a depends on the length of the thinned point (H; Ht) of the endless belt and the length N of the long nip.

Lubrication

One embodiment of the invention is based on the lubrication oil circulation of bearings by one or more digital valve groups 20.

Modern paper machines use roller oil lubrication for roller bearings on both the wet, drying and finishing side. Other bearings for paper machine equipment and motors, such as fan, peel drum, refiners, mixers, coating equipment, rollers, and cutter bearings, can also use circulating oil lubrication. Rotary oil lubrication is used in paper machines primarily to extend the life of bearings, since the purity of the lubricating oil is crucial to the life of the bearing.

Examples of paper machine rolls that are currently using circulating oil lubrication are: -wet end roll suction rolls, which are driven by planetary gear. The most common bearings for suction rolls are roller bearings on both the suction and the drive side, and oil is generally directed to the center of the bearings.

In the press section, the fibrous web passes through the roll nipples supported by the felts and most of the water still contained in the web is removed by compression. Roller ball bearings are most often used on press rolls on both the treatment and the drive side. Here, too, the oil is typically introduced into the center of the bearing and exits both sides of the bearing into the oil collection space and then out of the bearing housing through an outlet provided in the bearing housing. The design of the oil cycle is primarily influenced by the planned bearing temperature and the quality of the lubricating oil. The temperature of the bearing 5 is in turn influenced by e.g. roll diameter, rotation speed and weight.

Calendering improves the surface quality of the fibrous web for printing. The multi-roll calenders used for soft calendering of the fiber web have a plurality of alternating deflection compensated polymer coated rolls and heated thermal rolls, the roll nipples used for calendering the fiber web consisting of a teel blade with a rolled polymer face. The calendering event itself is influenced by e.g. the nip load prevailing on each roll nip, the temperature of the thermal roll and the moisture of the fibrous web. Because the nipples on the rollers in the multi-roll calender may have a different nip load, when designing the roller bearings, it is necessary to consider the position of the roll in the roll and the nip load on the 15 rolls. Because the rollers in the same roller roller calender often have different operating conditions, the amount of circulating oil lubricant introduced into each bearing and removed from the bearing housing may need to be dimensioned individually for roller and roller bearings, making the roller roller bearings easy to design. Typically, the amount of lubricant-20 lubricant in each bearing will have to be provided by feedback in an oval gear or by turbine measurement. Roller bearings are also the most widely used type of bearings in multi-roll calendars.

Recycling of lubricating oil is nowadays carried out by means of analogue control valves in many parts of paper machines such as press or calender roller bearings but also in other paper machine equipment and motor bearings. Paper machine rolls generally use spherical roller ball bearings, typical rolls being deflection compensated rolls for wet end calenders. In the case of circulating oil lubrication with analogue valves, the feedback control of the oil supply to each bearing has to be dimensioned and designed separately, making the bearing and its lubrication easily and costly.

Controlling the lubricating oil circulation with one or more digital valve assemblies of the digital valve assembly provides a significant advantage over the control of the circulation by analog valves. The lubricating oil is then dispensed through the digital valve units formed by one or more digital valve assemblies to bearings contained in a device such as a multi-roll calender. Preferably, each bearing has its own digital valve unit for dispensing the amount of lubricating oil required by the bearing at each instant. The volume flow rate of the lubricating oil circulation required by the various bearings of the papermaking machines and the extent of the volume flow change are such that 3-6 digital valves are suitably connected in parallel in the digital valve assembly serving each bearing. Suitably, the dispensing of the lubricating oil to the 5 bearings is accomplished by changing the opening of the oil-supplying digital valve assembly. If the lubricating oil circulation of an equipment such as a multi-roll calender is accomplished by bearing-specific digital valve assemblies, the oil supply to the digital valve assemblies may be accomplished in a manner similar to FIG. 2D, i.e. a common supply line 7 for the digital valve assemblies; 71.

10 The digital valve unit itself does not control the lubrication oil metering, but acts solely as a metering agent. If the control is, for example, the lubricating oil circulation of rolls of a multi may be required for all of the calender bearings quantity of oil is controlled centrally by a separate digital valve units connected to the control system on forward control based on the control strategy. Oh-15 jausjäijestelmällä calculated required for each bearing at a given time the lubricating oil, for example on the basis of the measuring data and for opening appropriate bearing supplying oil to the digital valve unit of the digital valve group of the digital valves to provide the desired flowrate of lubricating oil to the bearing. Thanks to the feedback control, the control system is fast. The control system 20 may thus be equipment specific, such as calender specific, since each bearing does not have to be designed with its own lubricating oil cycle. When the lubricating oil circulation control system is hardware-specific rather than bearing-specific, the control system is simplified and less expensive, if desired, even with digital valve units, feedback can be provided via current flow measurements, but the lubricating oil circulation can be performed well. By implementing a circulating oil lubrication via a digital valve unit, the control of the oil supply can be greatly simplified, even if the lubricating oil quantities supplied to the bearings vary. The oil supply adjustment thus made is accurate and fault-tolerant.

30 Adjusting the amount of air blown

One aspect of the invention relates to controlling the amount of air in compressed air blasting, especially in the head vent, when changing the type of paper being processed in a papermaking machine. Threading of the fiber web is particularly needed when transporting the end of the fiber web over open spaces for calendering, coating, presses and winding. When the paper-35 type is changed, the paper machine may need to use dozens of compressed air blows of different air volumes. At present, control valves are used to control the amount of air blown, which are practically fan-specific, since they can only regulate the amount of blowing air within a given narrow volume flow range at a time. In the resistance valve, air passes through a short throttle opening. The flow rate through the valve orifice depends on the differential pressure across the mouth of the valve orifice and the area of the orifice. The flow rate and the atmospheric pressure at each side of the orifice are controlled by adjusting the size of the throttle orifice in the resistor valve. Adjusting high-flow airflow with such an analog resistance valve is inaccurate, energy-wasting and expensive.

An embodiment of the invention for compressed air blowing is intended to overcome the drawbacks of the prior art.

It is an object of the invention to provide a method and apparatus for controlling the amount of compressed air blowing, particularly in connection with threading of a fiber web.

The method and apparatus of the invention achieve the above objects.

The method of this embodiment of the invention is based on passing compressed air through a set of digital valves in the compressed air flow duct having in parallel 2-8 generally 3-6 digital on / off valves. Preferably, the sizes of the valves in the digital valve group are selected such that, in the open position, the amount of air passing through the greater of two successive flow rate valves per unit of time is twice that of the smaller valve.

The size of the opening of the digital valve group is controlled by opening and closing the appropriate digital valve group on / off digital valves. The opening area determines the pressure difference between the airflow supplied to the digital valve assembly and the airflow passed through the digital valve assembly. The volume flow of the pressurized air passing through the digital valve assembly, in turn, is determined by the opening area and the aforementioned pressure difference. If the size of the openings in the digital valves of successive diameters is suitably selected, the digital valve assembly can effectively control the compressed air flow in the fibrous web end port, and the same airflow channel valve unit 30 can control the compressed air flow over a wide flow range. This adjustment of the compressed air flow rate in the paper machine head outlet significantly reduces the number of valve units required to control the compressed air flow. In addition, air volume control with the digital valve assembly 41 is significantly more accurate than throttle valves, with energy savings of up to 30-50% in large paper machine headpieces.

Digital Valve Controlled Heat Exchanger Heat exchangers are required for different applications on a paper machine. They are needed in other mu-5s for cooling lubricating oil coming from the process.

The heat exchangers used in the various applications of the papermaking machine are often oil-in-water heat exchangers, in which the oil flows on the primary side and the cooling water on the secondary side. At present, the control of the cooling water circulation rate has been accomplished with a pneumatic throttle valve supplied by the heat exchanger manufacturer, which, however, is expensive to purchase. Particularly in the cheapest heat exchangers, the proportion of the cooling water control valve to the total cost of the heat exchanger is disproportionate, necessitating the use of valves adapted to the heat exchanger in question. However, if customized cooling water circulation control valves not originally designed for the heat exchanger in question are used, these are often weaker than those designed for the actuator due to their energy and water economy. They are often inaccurate control characteristics, especially at low pri-maaripuolen for fluid flow that occur at cold start equipment.

The invention is intended to overcome the drawbacks of the prior art described above. Accordingly, it is an object of the invention to provide a liquid-to-liquid heat-20 exchanger in which a secondary-cycle liquid-circulation control system is as cost-effective as possible and simple in structure. In addition, the heat exchanger should be capable of accurately controlling the amount of fluid passing through the secondary side over the entire adjustment range.

The heat exchanger of the invention overcomes the drawbacks of the prior art.

In the heat exchanger of the invention, a heat transfer fluid, such as water, is fed to the secondary side of the heat exchanger via a digital valve assembly. Two to eight, preferably 3-6 on / off digital valves are connected in parallel to the digital valve assembly, depending on the volume flow required on the secondary side.

30 By using the digital valve group on the supply side of the heat exchanger, it is possible to obtain precise control of the heat exchanger at both low and high flow rates. The on / off digital valves are externally similar and differ only in their fluid-through-hole diameter, whereby the investment cost of the digital valve array 42 is substantially lower than previously used actuator-specific control valves. heat exchanger according to the invention, further advantages, it is noted that the same heat exchanger can be used in various applications, because the heat exchanger secondary side flow adjustable within wide limits laid-5 SA.

The heat exchanger of the invention is illustrated in more detail in Figure 5.

Figure 5 schematically shows an oil-in-water heat exchanger according to the invention.

Figure 5 shows an oil-in-water heat exchanger 9 in which the oil circulating on the primary side 92 is, for example, an oil circulating in a lubricating oil circuit. A secondary side of the heat exchanger 9, the cooling water supply 91 is integrated with a digital valve unit 100, comprising one digital valve group 10 with 6 parallel-connected on / off -digitaa 1-portional valve.

The primary side 92 of the circulating oil is cooled with water having a jäähdytyskapasiteet-15 (volumetric flow rate) must be dimensioned in such a way that, while the secondary side 91 vesikier-numeral can be cooled, and the hot oil having a temperature of about 200 ° C, and the slight heating of oil lubricated by the primary system cold start-OF PROCEDURE in connection with. Therefore, the volume flow range of the water circulation 92 must be very wide. The number of digital valves 1 contained in the digital valve group 10 and the volume flow through them 20 are adapted to the required cooling capacity. The heat exchanger 9 shown in the figure adjusts the cooling water to be supplied by a digital valve assembly 10 which includes 6 parallel on / off digital valves 1 in the cooling water supply flow 1. The flow through the volume flow in the valve is 2 times the volume flow of the smaller valve. Such a six-valve digital valve assembly 10 is capable of providing 31 different cooling water flow rates, whereby the potential flow rate starts from very small flows (volume flow V = 1) up to a multiple of 30 cooling water flows (max. IV + 2V + 16V + 4V).

Claims (47)

Method for treating deviations during the manufacture of a web of materials, characterized in that the method comprises at least the following steps: - identifying a deviation (H) position on the surface of a roller (5) or on the web of materials and estimating or calculating the arrival time of the deviation (H) to the nip (N) and the duration of the deviation in the nip, 15. to transmit to at least one digital valve unit (100) which regulates the nip pressure in the nip (N) a coupled control instruction (F) for a control system (4) for treating the deviation in the calender nip (N), - in accordance with the regulation instruction (F), by mediating at least one digital valve (1), reduce the nip pressure in the nip (N) no later than the deviation (H) when the nip (N) and Increase the nip pressure when the deviation leaves the nip. Method according to claim 1, characterized in that the control instruction (F) is in digital form, such as binary form and / or that the roll nip is a roll nip in a calender, press, wiper, coating device or ratchet device. Method according to Claim 1 or 2, characterized in that the control instruction (F) defines the volume flow of the fluid flowing through the digital valve unit (100) and / or the position of the coif of a control means (2) during the control period. 30 Method according to any of the preceding claims, characterized in that the volume flow of the fluid flowing through the digital valve group (10) of the digital valve unit (100) is changed according to the control instruction (F) by changing the opening (1A) of the relevant digital valve group, ie. by opening and closing the desired digital valves (1), in the digital valve group, which are connected in parallel to the flowing fluid flow. Method according to any of the preceding claims 1 - 4, characterized in that the method comprises at least the following steps: - to identify the position of the joint point (H; Ws) between two joined material webs, such as fiber webs (W), located on the material web as when the roll nip (N), anticlockwise to the direction of movement of the material web relative to the nip (N), and the extent of the joint point (H; Ws), - to estimate or calculate the time of arrival of the joint (Ws) to the nip (N) and the passage time for said seam point through said roller nip (N), - transmitting from the control system (4) a coupled control instruction (F) to at least one digital valve unit (100) which controls the roller pressure of the roller nip (N) to treat a deviation caused by the socket point (Ws) in said roll nip (N), - in accordance with the regulation instruction (F), reduce the roll pressure of the roll nip (N) via at least one digital valve (1) at the latest when the seam point (Ws) arrives at the roll nip and to increase the roll pressure as the seam point leaves the roll nip (N). 20 Method according to claim 5, characterized in that - the control instruction (F) comprises a relief pulse for the nip pressure in the roll nip, wherein the nip pressure in a given roll nip (N) is lowered by reducing the load pressure (Kp) directed by the roller of the hydraulic drive means (2). against the pouring arm (3), as well as the restoration pulse of the load, whereby the load pressure (Kp) which the hydraulic drive means (2) is directed to the same pouring arm (3) is restored - the relief pressure of the nip pressure (Np) and the reset pulse of the nip pressure are generated by changing it mutually. the ratio of the fluid flow volumes (V20a> V20b) arriving at different sides (20a, 20b) of the piston of the hydraulic drive member (2) with digital valves included in the digital valve groups (10) of the digital valve assembly (10) and thereby changing the fluid pressure (P20a) , P20b) traveling on different sides (20a, 20b) of the piston of the hydraulic drive (2) relative to the fluid volume flows (V20aT, V20bT) which arrives at different sides of the cow in equilibrium position and consequently in relation to the liquid pressures (P20a> P20bT) which travel on different sides of the cow. Process according to claim 6, characterized in that - the fluid volume flow flowing on the pressure side of a piston in a hydraulic drive (2), such as a hydraulic cylinder (20), is reduced by a relief pulse according to the control instruction (F) and at the same time the fluid pressure is reduced which rides on the pressure side of the hydraulic cylinder from said fluid pressure (P20bi) on the pressure side in equilibrium position and from the volume flow (V2οι> τ) to the lowered fluid pressure (P20bi) and to the lowered volume flow (V20bi) for a given period of time. the fluid volume flow (V20ba) traveling on the working side of the piston in equilibrium position in the same hydraulic drive means (20) and to the fluid pressure (P20aT) in the equilibrium position caused by this volume flow, the hydraulic drive means (2) acting on the load of the roller arm and arm (3); the first page's reduced volume flow (V20bi) and the lowered liquid pressure (P20a) are restored to the volume flow (V20 bT) and fluid pressure (P20bT) which saved in the previous equilibrium position, - with the regeneration pulse of the control instruction, the fluid volume flow flowing to the pressure side of a piston in a hydraulic drive means (2) such as a hydraulic cylinder (20) is increased and at the same time the fluid pressure is increased. the pressure side of the hydraulic cylinder from the pressure level (P20bi) in the equilibrium position of the first side and from the volume flow (V20bT) to the increased fluid pressure (P20b2) and to the increased volume flow (V20b2) for a given time in relation to the liquid volume flow ( at the work side equilibrium position in the same hydraulic drive means (20) and at the fluid pressure (P20aij in the equilibrium position caused by this volume flow, and then the increased volume flow (V20b2) is restored to the pressure side and pressure level (P20b2) to the volume level (V20b2). and the pressure level (P20bi) traveling in equilibrium position. Method according to claim 7, characterized in that 25. in order to generate the relief pulse according to the control instruction (F), the volume flow flowing through the opening (Ia) in a specific digital valve group (10) in a digital valve unit (100) is reduced first from the original volume flow. Equilibrium mode generated by a combination (hobij of digital valves (1) open in equilibrium mode) to a new lower value (V20bi) for the volume flow, by selecting a suitable combination (hobby) of open digital valves (1) in the digital valve group, whereby the volume flow flowing through them corresponds to the desired lowered volume flow value (V2obi), and then after a short period after the relief pulse is generated, the volume flow flowing through the combination of the digital valve group (10) is reset in the digital valve group (10). the original volume flow in equilibrium mode by selecting the original combination (hobby) i m-35 wt mode combination of open digital valves. - to generate a reset pulse for the load according to the control structure, the equilibrium position's volume flow (V) flowing through the valve combination (12ομ ·) of the digital valves (10) digital valves (1) which is in the open position in equilibrium position is first increased to a new higher volume flow ( V), by selecting a suitable valve combination (120b2) of open digital valves (1) in the same digital valve group (10), the volume flow flowing through them corresponding to the desired higher value (V20b2) for the volume flow on the pressure side (20b) , and then, after a short period after the reset pulse bends, the reset volume flow flowing through (Ia) the valve combination of the digital valve group (10) digital valves (1) which is in the open position as the equilibrium position volume flow is reset by selecting the original valve combination (12). equilibrium position as a combination of open digital valves, whereby they are achieved t the previous volume flow (V20bT) in equilibrium position on the pressure side (20b) of the piston. Method according to claim 8, characterized in that the nip pressure of the roll nip (N) is the same before the release of the relief pulse as after the release of the relief pulse. 15 Method according to any one of claims 5-9, characterized in that the relief pulse and the reset pulse for the nip pressure of the roll nip (N) are carried out in a device comprising several successive roll nips, such that the relief pulse's relief pulse and reset pulse occur synchronously with the successive roll nips. speed of the respective device. 20 Method according to claim 10, characterized in that the timing of the successive roll nip (N) pulse and reset pulse is affected, in addition to the arrival time of the joint point (H; Ws) to the said roller nip (N) and the passage time of the joint point (H; Ws). ) through the roll nip, in addition to the structural factors of the calendering roller set (50) and of pressure losses in the hydraulic system used. 25 Method according to any one of the preceding claims 1 - 4, characterized in that the method comprises at least the following steps: - identifying the position of a web break (H; Wk) located on the material web which arrives at the roller nip (N) counterclockwise against the direction of movement of the material web in relation to the roll nip (N), - to estimate or calculate the arrival time of the web break (H; Wk) to the roll nip (N) and its transit time through said roll nip (N), - to at least one digital valve unit (100) which regulating the nip pressure in a roll nip (N) send a coupled control instruction (F) from the control system (4) to treat the deviation caused by said web failure in the calender's said nip (N), - to open the nip (N) with the transmission of at least one a digital valve unit (100) according to the control instruction (F) at the latest when the web break arrives at said roller nip. 5 Method according to claim 12, characterized in that the roll nip (N) is opened by reducing the load directed at least towards one roll forming the roll nip by means of the hydraulic drive means (2), such that the load of the means (3) as the roller against said roller is reduced by changing the ratio of volume flows (V20b, V20a) arriving to the pressure side (20b) and the working side (20a) of said hydraulic drive means (2) via at least one digital valve assembly (100), the control instruction (F) for the opening (Ia) given for said digital valve assembly (s). Method according to Claim 13, characterized in that the control instruction (F) of the opening (Ia) comprises stepwise lowering of the load pressure (Pk) in a member (3) which affects the pressure on a roller located in a roll nip (N). between two rollers, such that at the beginning of the opening of the roll nip (N) the load pressure of the hydraulic drive means (2) on said pressure setting means (3) is rapidly reduced (step 1) to a given load pressure (Pk) and then the hydraulic drive means are reduced. (2) load pressure (Pk) towards said pressure setting means more slowly, step by step (step 2) until the desired opening of the roll nip (N) is reached. Method according to claim 14, characterized in that part of the opening of the roll nip (N) according to the control instruction (F) is carried out via the digital valve unit (100) with a coupled feed forward method and a part with a feedback coupled method with 25 using one or more slide valves. Method according to claim 15, characterized in that the initial acceleration step (step 1) of the opening of the roll nip is performed by means of the digital valve unit (100) and the slower stepwise further opening (step 2) of the roll nip is performed with one or more slide valves. Method according to any of Claims 13 to 16, characterized in that the ratio between the volume flows (V20b, V2oa) arriving at the pressure side (20b) of the hydraulic drive member (2) and working side (20a) is changed, by changing the opening of the at least a first digital valve unit (10) of a digital valve unit (100), so that in equilibrium position, prior to the opening of the roll nip, fluid volume flow (V2obT) is reduced in equilibrium position flowing through said digital valve group to the pressure side (20b) of said hydraulic drive member (2b) all the way to the new lower volume flow (V2obi) and at the same time possibly by removing liquid from the pressure side (20b) of the hydraulic drive (2) via the digital valve group leading to the drainage line (7; 72), the pressure side of the hydraulic drive means drops from the original fluid pressure (P20bT) in equilibrium to a lower fluid pressure (P20bi) · 5 Method according to claim 17, characterized in that the opening (Ia) of the first digital valve group (10) is reduced, such that the volume flow (V20b) flowing to the pressure side (20b) of the hydraulic drive means (2b) is reduced from the equilibrium position's liquid flow ( V20bT) up to a given lower flow (V20bi), which lowered fluid volume flow (V20bi) corresponds to a given fluid pressure (P20bi) on the pressure side of the hydraulic drive member (2) lowered from the pressure (Ρ2 <η> τ) in equilibrium position as the amount of volume flow flowing to the working side (20a) of the hydraulic drive member (2) is increased from the equilibrium position's volume flow (V20ai), which is equivalent to a given fluid pressure (P20ai) in the equilibrium position, to a given increased volume flow (V20ai) on the working side , wherein the increased fluid volume flow corresponds to a given increased fluid pressure (P20a1) on the working side of the hydraulic drive means, by increasing the opening (Ia) of the second digital valve valve. open (10). Method according to Claim 17 or 18, characterized in that in the opening acceleration step (Fig. 3B step 1), the opening (120) of at least one digital valve group 20 (10) is reduced by a digital valve unit (100) controlling the fluid flow to the hydraulic drive means. pressure side (20b) from the original opening (l2obT) in equilibrium position corresponding to a given fluid volume flow in equilibrium position to the pressure side (V20bi) »to a new reduced opening (Ia) of the same digital valve unit (100) digital valve group with which the desired valve is achieved decreased the fluid volume flow (V20M) on the pressure side (20b) of the hydraulic drive means by selecting a new valve combination (hobby) of the open valves (1) in the digital valve group (10) and possibly by removing hydraulic fluid from the pressure side of the hydraulic drive member ( 20b) via the digital valve group (10) leading to the drainage line (7; 72). 30 Method according to claim 18, characterized in that the amount of volume flow flowing to the working side (20a) of the hydraulic drive means (2a) is increased from the equilibrium position's volume flow (V20aT), which corresponds to a given fluid pressure (P20ar) in the equilibrium position ( h) of open valves (1) in equilibrium position in a digital valve group (10) of the digital valve assembly (100) all the way to a specific increased volume flow (V20a), whereby the increased liquid volume flow (V20a) is matched by a given increased fluid pressure (P20a) the working side of the hydraulic drive means, by increasing the opening of the second digital valve group (10), so as to select such a new valve combination (l20ai) of open valves (1) in the digital valve group (10) of the digital valve unit (100), which controls the amount of volume flow / flow to the working side (20a) of the hydraulic drive means, to achieve said increased volume flow (V20ai). Method according to any one of claims 13-16, characterized in that the stepwise slower opening (step 2) of the roll nip (N) after the acceleration step (step 1. at the opening of the roll nip is performed by means of at least one digital valve group (100). 22. A method according to claim 21, characterized in that the stepwise continued opening of the roll nip is carried out by gradually reducing the difference between the fluid pressures (P2ob, P20a) 10 which touch at the (20b) piston end and at (20a) the piston rod in the respective hydraulic drive means ( 2) using at least two different digital valve groups (10). 23. A method according to claim 22, characterized in that, in the further stepwise opening (step 2) of the roll nip, the volume flow (V2ot>) which is led to the pressure side (20b) of the hydraulic drive means (2b) and thus also the liquid pressure (P20b) is increased. at the pressure side (20b) and possibly incrementally reduced at the same time a little back pressure (P20a) which raises on the working side (20a) of the piston, such that the fluid pressures that travel on the pressure side and the working side of the hydraulic drive member (2) are at equilibrium at the end of the opening stage, whereby a new liquid pressure (P20anO in equilibrium position raises on the working side (20a) of the piston and on the pressure side (20b) of the piston raises a new liquid pressure (P2otm) in the equilibrium position, and these new equilibrium liquid pressure (P2oan, P20bn) is than the liquid pressures in the equilibrium position (P2o3t, P20bT) which rescued prior to opening the roll nip both on the working side (20a) of the piston and on its pressure side (20b). The method according to claim 23, characterized in that the volume flow conducted to the pressure side (20b) of the hydraulic drive member (2) is incrementally increased by at least one digital valve group (10) of the digital valve unit (100) by selecting on the pressure side (20b) successive openings (202). , I20b3 ”. L20bn) of the digital valve group (10) which achieves increasing fluid volume flows (V20b2, V2ob3-V2obn) · 30 25. A method according to claim 23 or 24, characterized in that the back pressure (P2o) traveling on the working side (20a) of the hydraulic drive means is gradually reduced by at least one digital valve group (10) by the digital valve unit (100) by selecting on the pressure side (20b) successive openings. (l2oa2 ', I20a3' -l20an) of the digital valve group (10) which achieves decreasing fluid volume flows (V2oa2, V2oa3-V2oan). Method according to any one of claims 1-4, characterized in that - the position of a deviation (H) on the surface of a fiber web (W) arriving at a multi-roller calender (500), such as an unevenness in the surface, counterclockwise to the fiber web direction of movement, before each roll nip (N), is identified, and the arrival time of the deviation to the respective roll nip (N) and the throughput time through each roll nip (N) is estimated or calculated, - to at least one digital valve unit (100) which regulates the nip pressure in each roll nip ( N) a coupled control instruction (F) is transmitted from the control system to process the deviation in the roller nip (N) of the multi-roller calendar (500), 10 - in accordance with the regulation instruction, is reduced by mediating at least one digital valve (1) the pinch pressure in the roller nip (N) ) most recently when the deviation (H) reaches the roll nip (N) and the pressure increases as the deviation leaves said roll nip. 15 Method according to claim 26, characterized in that - the control instruction (F) comprises a relief pulse for the nip pressure in the roll nip (N), whereby the nip pressure (P) in a specific roll nip (N) of a multiple roll calender (500) is reduced the load pressure (Kp) directed to the pouring arm (3) from the cylinder (20) of the hydraulic cylinders, and the restoring pulse of the load, whereby the load pressure (Pk) directed from the hydraulic cylinder (20) to the same pouring arm (3) is restored, - the relief pressure of the nip pressure (Np) and the nip pressure (Np) reset pulse is generated by changing the opening of the digital valve assembly (10) of the digital valve assembly (10), such that the relationship between fluid volume flows (V20a, V20b) arriving at different sides (20a, 20b) of the hydraulic cylinder (20) piston from the digital valve groups (10) is changed and thus also the ratio of the fluid pressures (P20a, P20b) traveling on different sides (20a, 20b) of the hydraulic drive the piston (2) of the piston in relation to the fluid volume flows (V20aT, V20bi) arriving at different sides of the coefficient in equilibrium and to the liquid pressures (P20aT, P20bT) which travel on different sides of the coefficient. Method according to any one of claims 1 to 4, characterized in that - the position of a deviation point (H) on the surface of an application roller or its counter-roll of the coating or surface bonding device of the fiber web (W), as well as an unevenness on the surface of the application roller or its counter-roll is identified, - the time of arrival of the deviation site (H), such as an irregularity on the surface of the application roll or its counter-roll, to a nip roll between the application roll and its counter-roll, and the passage time through said roll nip is estimated or calculated (5) at least one 100) which regulates the nip pressure of the roll nip (N), an associated control instruction (F) is sent from the control system (4) to treat the deviation point at the roll nip (N) between the application roll and its counter roll, - in accordance with the regulation instruction (F), the nip pressure of the roll nip 10 is reduced. a digital valve at the latest when the deflection point arrives at the roll nip and increases the nip pressure where the deviation site leaves the roll nip (N). Method according to any of claims 1-4, characterized in that the position of a deviation point (H) on a paper web (W) rolled on a bearing roller, such as irregularities in the surface of rolled paper, is identified counterclockwise to the direction of movement of the paper web, before roll nip (N) between a bearing roll and its counter roll, such as support roll and / or a forward roll, and the arrival time of the deviation site (H) to a roll nip (N) between the bearing roll and its counter roll and the throughput time through said one or more roll nips is estimated or calculated; - at least one digital valve unit (100) regulating said roll nip (N) pressure is sent a coupled control instruction (F) from the control system (4) to treat the deviation position (H) at the roll nip (N) between the bearing roll and its supporting roll and / or forward roll, - in accordance with the control instruction (F), the roll pressure of the roll nip (N) is reduced via at least one digital valve unit (100) at the latest when the departure position (H) arrived more to the roll nip between the bearing roll and its supporting roll and / or the forward roll, and the nip pressure is increased when the deviation site leaves said one or more roll nips. 30 The method according to any of claims 28 or 29, characterized in that - the control instruction comprises a relief pulse for the nip pressure of the roll nip, wherein the nip pressure (Np) of the roll nip between the roll and its counter roll is lowered by reducing the loading pressure directed against the member (3) supporting / pressurizing the roller and / or its supporting roller from the hydraulic drive (2), as well as the restoring pulse of the load, whereby the load pressure directed from the hydraulic drive (2) to the same member (3) is reset, - the nip pressure (Np) relief pulse and nip pressure reset pulse are generated by changing the relative ratio of fluid volume flows (V20a, V20b) arriving at different sides (20a, 20b) of the piston of the hydraulic drive (2) with digital valves included in the digital valve assembly (100) ), thereby changing the fluid pressures (P20a, P20b) that travel on different sides (20a, 20b) of the hydraulic The piston of the drive means relative to the fluid volume flows (V20aT> V20bi) arriving at different sides of the coil in equilibrium position and consequently to the fluid pressures (P2oa, P20bT) which travel on different sides of the coil. 10 Method according to any of claims 1-4, characterized in that the method comprises at least the following steps: - identifying the position of the site (H; Ht) of an endless band (8a) rotating in the long nip (N ) of a shoe calender (800), counterclockwise to the direction of rotation of the endless belt relative to the longitudinal nip (N), which is thinner than the rest of the endless belt, and the extent of the thinner site (H; Ht), wherein said longitudinal nip ( N) is formed between the endless belt (8a) rotating on a shoe element (8b) by a shoe roll (8) and the shoe roll counter (80), to estimate or calculate the arrival time of the place (H; Ht) of the the endless band (8a) thinner than the rest of the endless band to the longitudinal nip (N) and the throughput time of the place (H; Ht) of the endless band (8a) thinner than the rest of the endless band through the longitudinal nip (N) ), 25 - to send an attached control instruction to at least one a digital valve assembly (100) which regulates the longitudinal nip (N) pressure of the control system (4) to treat a deviation in the longitudinal nip (N) caused by the site (H; Ht) of the endless band thinner than the rest of the endless band, 30 - reducing the nip pressure in a longitudinal nip (N) according to the control instruction (F) by means of at least one digital valve assembly (100) at the most recent location (H; Ht) of the endless band (8a) which is thinner than the rest of the endless band arrives at the longitudinal nip and to increase the nip pressure as this thinner place leaves the longitudinal nip (N). 35 Method according to claim 31, characterized in that - the control instruction (F) comprises a relief pulse for the longitudinal pressure (P) of the longitudinal nip (P1), wherein the longitudinal pressure (P) of the longitudinal nip (N) is lowered by reducing the load pressure (P1) as the hydraulic cylinders ( 200) is directed to the shoe element (8b) and the nip pressure reset pulse, the load pressure (P1) directed by the hydraulic drive members (200) to the same shoe element (8b) is restored, 5. the nip pressure relief pulse and the nip pressure reset pulse are generated by changing the opening digital valve assembly (100) digital valve groups, such that the relative relationship between fluid volume flows arriving at different sides of the piston of the hydraulic cylinders (200) is changed, and thus the fluid pressures traveling on different sides of the piston of the hydraulic drive means (200) are changed in relation to fluid volume. arrives at different sides of the cow in equilibrium position and consequently in the story they add to the fluid pressures that travel on different sides of the cow. The method according to claim 31 or 32, characterized in that the position (H; Ht) of the location of the endless band (8a) thinner than the rest of the endless band is identified on the basis of a measurement of the endless band of the surface pressure (P2) in the longitudinal nip (N) and on a measurement of the load pressure (P1) on the shoe element (8b) caused by the hydraulic cylinders (200) in the longitudinal nip (N) and on generating the differential pressure between these pressures (P1, P2) . 20 34. A method according to any of claims 31 to 33, characterized in that the relief pulse of the control instruction (F) takes into account the speed of rotation of the endless band (8a), the length of the news piece (N) in the machine direction and the area and degree of thinning of the place (H; Ht ) of the endless band thinner than the rest of the endless band. 25 35. A method according to any one of claims 31 to 34, characterized in that - at the relief pulse of the control instruction (F), the volume flow of the liquid flowing to the first sides of the pistons in the hydraulic cylinders (200) which pressurizes the shoe element (8b) and the liquid pressure which rises, is reduced. on the front sides of the hydraulic cylinders (200) to obtain the fluid pressure in the equilibrium position of the first sides and from the volume flow to the lowered fluid pressure and to the reduced volume flow for a given time, and then the lowered volume flow residing on the first sides is restored. the pistons of the cylinders (200) and the fluid pressure in equilibrium position on the first side of the piston of said hydraulic cylinders as the saving volume flow and liquid pressure, the liquid pressures traveling on the first sides of the hydraulic cylinders (200) in said equilibrium position are the same as the liquid pressures ( which rides on the other sides of the hydraulic the pistons of the cylinders (200) in the equilibrium position, - with the reset pulse of the control instruction, the fluid volume flow flowing on the first side faces of the pistons of the hydraulic cylinders (200) and at the same time the liquid pressure on the first sides of the pistons of the hydraulic cylinders (200) is equalized the first sides of the hydraulic cylinders (200) and from the volume flow to the increased fluid pressure and to the increased volume flow, and then the increased volume flow is restored to the first sides of the pistons of the hydraulic cylinders (200) and the fluid pressure in equilibrium volume flow as the fluid pressure on the first side of the hydraulic cylinders (200) in said equilibrium position is the same as the fluid pressures (counterpressures) in the equilibrium position on the other sides of the pistons of the hydraulic cylinders (200). 36. A method according to claim 35, characterized in that - to generate a relief pulse according to the control instruction (F), the volume flow (V) flowing through the combination (Ia) of digital valves in the open position of a given digital valve group (10) of the digital valve unit is reduced. (100) first from the equilibrium volumetric flow, performed by a given combination of open digital valves (1) of the digital valve group (10) in equilibrium, to a new smaller value for the volume flow, by selecting an appropriate combination of open digital valves (1) in the same digital valve group (10), wherein the volume flow flowing through it corresponds to the desired lowered volume flow value, and then a short period after the relief pulse has been generated, the volume flow (V) flowing through the combination of open digital valves (1) is restored. ) in the digital valve group (10) as the original volume flow in the equilibrium position by selecting it equilibrated combination in equilibrium position as combination of open digital valves (21) in the digital valve group, - to generate the load reset pulse according to the control instruction (F), the volume flow (V) flowing through a combination (1A) of open digital valves (1) is increased. in a given digital valve group (10) of the digital valve unit (100) first from the original volume flow which is in equilibrium position, performed by a given combination in equilibrium position of open digital valves (1) in the digital valve group (10) in equilibrium position, to a new higher value for the volume flow, by selecting a suitable combination of open digital valves (1) in the same digital valve group (10), the volume flow flowing through it corresponding to the desired increased value for the volume flow and then after a short period from when the reset pulse is generated. the volume flow (V) flowing through the combination of open digital valves is restored smiles (1) in the digital valve group as the original volume flow in the equilibrium position, by selecting the original combination in the equilibrium position as the combination for the open digital valves (1) in the digital valve group. An apparatus for carrying out the method of claim 1 in a calender comprising at least one roller set clamped to the calender body comprising at least two rolls (5) between which is formed a roll nip (N), between which a material web can be calendered, characterized in of the plant comprising - a control system (4) comprising means for identifying the position of a deviation (H) on the material web or on the calender roll (5), means for estimating or calculating the arrival time of the deviation arriving at the roll nip (N ) between two rollers, means for estimating or calculating the duration of the deviation in the same roll nip (N) and means for providing a coupled control instruction (F), with which regulation instruction it is possible to treat deviations (H) arriving at the roller nip (N), - a control system comprising at least one digital valve assembly (100), with which it is possible to control a nip pressure of the roll nip (N) according to a control instruction which is phased by the control system with coupled control by means of at least one hydraulic drive means (2), so that the nip pressure of the roll nip can be lowered by at least one digital valve (1) in the digital valve unit (100) according to the control instruction ( F) at the latest when the deviation (H) arrives at the roll nip, and the nip pressure can be increased as the deviation leaves the roll nip (N). 20 Installation according to claim 37, characterized in that the hydraulic drive means (2) is a hydraulic cylinder (20). Installation according to claim 37 or 38, characterized in that the control system 25 (4) comprises a digital valve unit (100) for respective hydraulic drive means (2). Installation according to any of claims 37 - 39, characterized in that the digital valves in the digital valve unit (100) of the digital valve unit (100) have two positions; open and closed. Installation according to claim 40, characterized in that the volume flow flowing through the valve with the larger nominal volume flow in the digital valves group (10) digital valves with successive nominal volume flows is two times as large as the volume flow flowing through the valve with the smaller nominal volume flow. An installation according to any of claims 37 - 41, characterized in that the installation is a multiple roll calender (500), wherein a number of intermediate rolls (5; 5a) fall between the lowest roll (5; 5b) and the highest roll (5; 5b). ), the two ends of the intermediate rollers comprising the roll arms (3) of the rollers, each of which has a hydraulic drive member (2) coupled, the load effect of the roll nip (N) between two rollers can be changed by a control system comprising at least one digital valve unit (100) . Installation according to claim 42, characterized in that the control system comprises a digital valve unit (100) with four digital valve groups (10) for each hydraulic drive means (2), with which it is possible to control the fluid pressure (P2oa, P20b) traveling on the pressure side ( 20b) and the working side (20a) of the respective hydraulic drive means (2). Installation according to claim 43, characterized in that each intermediate roll (5; 5 a) of the roller set (50) comprises a pouring arm (3) at both ends, the function of which is controlled by the hydraulic drive means (2) and each hydraulic drive member (29). functions are controlled separately with their own digital valve unit (100), these digital valve units being functionally synchronized via the control system (4), without there being a direct flow connection for hydraulic fluid between them, each digital valve unit (100) having its own inlet for pressurized hydraulic fluid from the inlet line (7; 71) of hydraulic fluid and a separate outlet for hydraulic fluid into the tank line (7; 72). An installation according to claim 44, characterized in that the control of the hydraulic drive means (2) which presses the pouring arm (3) at each end of each intermediate roller (5; 5a) is carried out with mutually identical digital valve units (100; 100 ', 100'). ), wherein the control instructions (F) sent to their control circuits if the control system are identical for a given period of time. An installation according to claim 45, characterized in that the control instruction (F) is a volume flow control (V) control instruction (V) arriving at or flowing from the hydraulic drive (2) or a control instruction F (X) for the position of the the piston of the hydraulic drive means (2) and that the control of the hydraulic drive means (2) according to the control instructions occurs without feedback, in a coupled control mode. An installation according to any of claims 37 - 41, characterized in that the calender is a shoe calender (800) comprising a shoe roll (8) consisting of a shoe element (8b), on which is placed a rotatable endless belt (8a) , wherein said shoe element (8b) can be manually pressurized below a given pressure (P1) by means of a plurality of hydraulic cylinders (200) supporting the stationary body (85) of the calender, so that the rotating endless belt (8b) rotating on it is pressed against the counter roll (80) of the shoe roll with a given pressure (P2) in the longitudinal nip (N), which longitudinal nip (N) falls between the counter roll (80) and the endless belt (8b) and wherein the web (W) which is to be The calender is controlled to the longitudinal nip (N), whereby the pressure generated by the hydraulic cylinders (200) can be controlled by at least one digital valve unit (100), for which it is possible to provide a control instruction (F) by means of the control system (4).