JP2001115386A - Method of dehydration used for papermaking and device for controlling dehydrator mounted on twin-wire former - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of dehydration used for papermaking, generating an appropriate inner pressure in paper stock in accordance with a concentration of the stock, improving dispersibility of fibers in the paper stock, and therefore capable of making the paper excellent in formation, and to provide a dehydrator-controlling device therefor. SOLUTION: This dehydrator-controlling device for controlling plural dehydrators mounted on the twin-wire is equipped with concentration-estimating measures 50, 53, a dehydrator-determining measure 54, a dehydrator operation-controlling measure 55, wherein the concentration-estimating measures 50, 53 estimate each concentration of the paper stock 7 at plural points located on the travel route from the upstream to the downstream of the paper stock 1 traveling along plural dehydrators 21, the dehydrator-determining measure 54 determines a hydrator stationed at a position where the concentration of the paper stock 7 estimated by the concentration-estimating measures 50, 53 meets the predetermined concentration suitable for obtaining an aimed paper quality as the operating hydrator, and the dehydrator operation-controlling measure 55 outputs control signals to the operating dehydrator 21 determined by the dehydrator-determining measure 54 so as to perform the dehydration operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dewatering method used for papermaking, in which dewatering is performed using a dewatering device having a dewatering blade, for example, and a dewatering member control device provided in a twin-wire former.

[0002]

2. Description of the Related Art Conventionally, there is a twin wire former as a paper layer forming apparatus of a paper machine. This twin wire former has two wires each formed in a loop shape, and a paper raw material liquid is used for the two wire formers. While running while being sandwiched between the wires, a fiber mat is gradually formed by removing water from the paper raw material liquid by various dehydrating devices, and this grows to form a paper web. It is going to go.

For example, FIG. 9 is a schematic configuration diagram showing an example of this twin-wire former, and a paper layer forming apparatus of the twin-wire former will be described with reference to FIG.
As shown in FIG.
Is supplied to the head box 6.
From inside, it is ejected toward a gap (papermaking gap) 5 formed by the top wire 1 and the bottom wire 2.

The top wire 1 is guided by a forming roll 3 and guide rolls 31A to 31D, and the bottom wire 2 is guided by a breast roll 4, a suction scooter roll (suction roll) 12, and guide rolls 32A to 32E. Wire 1,2
Is rotated in the direction indicated by the arrow in FIG. A gap 5 is formed between the wires 1 and 2, and the paper material liquid 7 ejected from the head box 6 is subjected to various dehydration while traveling in the gap 5 at the same speed as the wires 1 and 2. Equipment 14,
The paper web 13 is formed while being dehydrated by 23 and 11.

That is, a plurality of dewatering blades (dewatering members) 9 disposed at intervals from each other on the bottom wire 2 side downstream of the forming roll 3 and the breast roll 4.
Is provided. The plurality of dewatering blades 9 are in contact with the bottom wire 2, form the bottom wire 2 and the top wire 1 at a predetermined curvature (radius of curvature R), and form the bottom wire 2 and the top wire 1.
Is gradually narrowed toward the downstream side.

Therefore, the paper stock liquid 7 passing through the first dewatering device 14 travels in the gap 5 gradually narrowed at a predetermined curvature (radius of curvature R), while the dewatering pressure generated by the plurality of dewatering blades 9. Thereby, dehydration is performed on both sides (the bottom wire 2 side and the top wire 1 side),
A fiber mat is gradually formed. First dehydrator 14
Downstream of the second dehydrator 23 and the counter dehydrator 15
Is provided. These dehydrating devices 23 and 15 are disposed so as to face each other with the top wire 1, paper raw material liquid 7 and bottom wire 2 interposed therebetween, and the second dehydrating device 23 is provided on the top wire 1 side, and The device 15 is provided on the bottom wire 2 side.

FIG. 10 is an enlarged view of a main part of the dehydrating devices 23 and 15, and a second dehydrating device 23 has a plurality of dehydrating blades (a plurality of dehydrating blades) provided at intervals on an apparatus main body 23A. (A fixed type dewatering blade, dewatering member) 20. These dehydrating blades 20 are used for the device main body 2.
3A, each dewatering blade 20 is mounted on a mounting portion 23B, and each dewatering blade 20 has a wedge-shaped dewatering blade (hereinafter, referred to as a wedge-shaped dewatering blade) having a flat surface portion 20A and an inclined surface portion 20B.
(Referred to as a wedge-shaped dewatering blade).

[0008] Of these, a plane portion (hereinafter simply referred to as a plane)
Reference numeral 20A is provided in a loop of the top wire 1 so as to contact the top wire 1 and support the top wire 1, and has an inclined surface portion (hereinafter simply referred to as an inclined surface) 20.
B is formed on the wire entry side (upstream in the wire traveling direction) with respect to the plane 20A, and is formed so as to be gradually separated from the top wire 1 toward the upstream in the wire traveling direction.

Therefore, a wedge-shaped space (referred to as a wedge-shaped space) 20C is formed between the inclined surface 20B and the top wire 1. Note that the inclination angle θ of the inclined surface 20B is referred to as a wedge-angle. Further, the opposed dewatering device 15 includes a plurality of dewatering blades (opposed dewatering blades, dewatering members) 21 arranged on the device main body 15A at intervals. These dehydrating blades 21
Presses the bottom wire 2, but the pressing force by the dehydrating blade 21 can be adjusted by fluid pressure from outside during operation. For this reason, the dewatering blade 21
Is also referred to as a movable dehydrating blade or a flexible dehydrating blade.

That is, although the dewatering blade 21 is mounted on the base 22, the base 22 can be moved relative to the equipment main body 15A in a direction of coming and going from the bottom wire 2, and the base 22 and the equipment main body 15A are connected to each other. By adjusting the fluid pressure (for example, air pressure, oil pressure, etc.) in the tube 24 interposed between the bottom wire 2 of the dehydrating blade 21
Pressing force (pressing force) can be adjusted.

By adjusting the pressing force of the dewatering blade 21, the top wire 1 and the bottom wire 2 are adjusted.
The dehydration pressure generated in the paper raw material liquid 7 sandwiched between them can be adjusted. Further, as shown in FIG. 9, a third dehydrating device 11, also called a suction box, is provided in the loop of the bottom wire 2 on the downstream side of the second dehydrating device 23. The paper material liquid 7 is dewatered by vacuum by the third dewatering device 11 and the suction couching roll (suction roll) 12, and the web 13 thus formed is securely transferred onto the bottom wire 2. It is transported to the next press part by a suction pickup roll (not shown).

[0012]

As described above, in the conventional twin-wire former, all of the plurality of opposed dewatering blades 21 are moved toward the fixed dewatering blade 20 in accordance with the paper to be formed, thereby forming the second dewatering blade. Paper sandwiched between the two wires 1 and 2 so that the same pressing force is exerted by the dehydrating blades 20 and 21 over the entire length from the upstream side to the downstream side in the wire running direction of the device 23 and the opposed dewatering device 15. An appropriate internal pressure is generated in the raw material liquid 7, whereby the dispersibility of the fibers of the paper raw material liquid 7 is improved, and a paper excellent in formation can be formed.

However, the paper raw material liquid 7 that is transported sandwiched between the two wires 1 and 2 is gradually dehydrated when transported between the second dehydrator 23 and the opposing dehydrator 15. Therefore, the raw material concentration (also referred to as mat concentration or papermaking concentration) changes every moment. For this reason, as described above, the settings such as the speed and basis weight are changed according to the paper to be formed, and a plurality (for example, 4 to 8 pieces) arranged in series from the upstream side to the downstream side in the wire running direction is used. By moving all of the opposed dewatering blades 21) to the fixed dewatering blade 20 side, the dewatering blade 2
When adjusting the pressing force by 0, 21, the two wires 1, 2, which transport the paper raw material liquid 7 therebetween, are connected to the second dehydrating device 23.
When it is transported between the dewatering device 15 and the counter dewatering device 15, it is pressed by the dewatering blades 20 and 21 with the same pressing force over the entire length from the upstream side to the downstream side in the wire running direction.
There is a problem that the amount of wear of the wires 1 and 2 is increased, thereby shortening the life of the wires 1 and 2.

If the life of the wires 1 and 2 is shortened, the frequency of replacement of the wires 1 and 2 will increase. If the frequency of replacement of the wires 1 and 2 increases in this way, the machine must be stopped at the time of wire replacement, so that the operation rate of the machine decreases, and the production efficiency decreases. On the other hand, as described above, the paper raw material liquid 7 that is transported sandwiched between the two wires 1 and 2 gradually dehydrates when transported between the second dehydrator 23 and the opposing dehydrator 15. As the raw material concentration (also referred to as mat concentration or papermaking concentration) changes every moment, the dewatering blades 20 and 2 extend over the entire length from the upstream side to the downstream side in the wire running direction.
1, the paper raw material liquid 7 does not need to be pressed with the same pressing force.
It is considered that, if an appropriate internal pressure according to the concentration of is generated in the paper raw material liquid 7, the dispersibility of the fibers of the paper raw material liquid 7 is improved, and a paper excellent in formation can be formed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an appropriate internal pressure is generated in a paper raw material liquid in accordance with the concentration of the paper raw material liquid to improve the dispersibility of fibers in the paper raw material liquid. ,
Dehydration used for papermaking, which enables the production of paper with excellent formation and reduces friction between the dewatering member and the wire to reduce the amount of wire wear and extend the life of the wire. An object of the present invention is to provide a method and a control device for a dewatering member provided in a twin-wire former.

[0016]

According to the first aspect of the present invention, there is provided a dewatering method for use in papermaking according to the present invention, wherein a paper raw material liquid is sandwiched between papermaking gaps formed between two wires forming a loop. In a dewatering method in which a wire is operated and a paper raw material liquid is dewatered while traveling along a plurality of dewatering members, a predetermined concentration for obtaining a target paper quality and a predetermined pressing force acting on the paper raw material liquid are set. Estimating the concentrations of the paper raw material liquids at a plurality of locations from the upstream side to the downstream side in the traveling direction, and determining the dewatering member disposed at the position where the estimated concentration is the predetermined concentration as the working dewatering member, Is operated so that the pressing force against the paper raw material liquid becomes a predetermined pressing force, thereby dewatering the paper raw material liquid.

According to a second aspect of the present invention, there is provided a dewatering method for use in papermaking according to the present invention, wherein a paper material liquid is inserted into a papermaking gap formed between two wires forming a loop, and the wires are operated to produce a plurality of paper material liquids. In the dewatering method of dewatering while running along the dewatering member, the concentration of the paper raw material liquid is estimated at a plurality of locations from the upstream side to the downstream side in the running direction of the paper raw material liquid, and the estimated concentration and the plurality of dewatering are determined. A density-dewatering member conversion table is created by associating the arrangement positions of the members with each other, and the dewatering member to be operated is determined using the created conversion table in accordance with a predetermined density at which a desired paper quality can be obtained. It is characterized in that the member is operated to dehydrate the paper raw material liquid.

According to a third aspect of the present invention, there is provided a dewatering member control device provided in the twin wire former according to the present invention, wherein a papermaking gap is formed between two wires forming a loop, and a paper raw material liquid is sandwiched between the papermaking gaps. In a dewatering member control device for controlling a plurality of dewatering members provided in a twin-wire former for operating a wire to dewater while running a paper raw material liquid, an upstream side in a running direction of a paper raw material liquid running along the plurality of dewatering members is provided. Estimating means for estimating the concentration of the paper raw material liquid at a plurality of locations extending from the downstream side to the downstream side, and distributing the paper raw material liquid at a position where the concentration of the paper raw material liquid estimated by the concentration estimating means is a predetermined concentration capable of obtaining a target paper quality. A dehydrating member determining means for determining the provided dewatering member as an operating dewatering member; and a control signal for operating the operating dewatering member determined by the dewatering member determining means. It is characterized in that it comprises a force dewatering member operation control means.

According to a fourth aspect of the present invention, there is provided a dewatering member control device provided in a twin wire former according to the present invention, wherein a papermaking gap is formed between two wires forming a loop, and a paper raw material liquid is sandwiched between the papermaking gaps. In the dewatering member control device for controlling a plurality of dewatering members provided in a twin wire former for operating the wire and dewatering while running the paper raw material liquid, the running of the paper raw material liquid running along the plurality of dewatering members Concentration estimating means for estimating the concentration of the paper stock solution at a plurality of locations from the upstream side to the downstream side in the direction, and a concentration-dewatering member conversion table in which the respective concentrations estimated by the concentration estimating means are associated with a plurality of dehydrating members. Conversion table creating means for creating a target paper quality using a conversion table created by the conversion table creating means. It is characterized in that it comprises a dewatering member determining means for determining a dehydration member for actuating, and a dewatering member operation control means for outputting a control signal to actuate the actuating dewatering member which is determined by the dewatering member determination unit Te.

According to a fifth aspect of the present invention, in the twin wire former of the present invention, the dewatering member determining means includes a plurality of densities which are prepared in advance for each papermaking speed. A dehydrating member conversion table is provided, and the operating dehydrating member is determined according to a predetermined concentration using any one of a plurality of conversion tables.

According to a sixth aspect of the present invention, there is provided a dewatering member control device provided in the twin wire former according to the present invention.
Wherein the concentration estimating means estimates the concentration of the paper raw material liquid based on the thickness and basis weight of the paper raw material liquid. According to a seventh aspect of the present invention, in the twin wire former of the present invention, in the configuration of the sixth aspect, the concentration estimating means obtains the thickness of the paper raw material liquid from the impedance of the paper raw material liquid. Features.

In the dewatering method used for papermaking according to the present invention, the paper raw material liquid is inserted into a papermaking gap formed between two wires forming a loop, and the wires are operated to produce a plurality of paper raw material liquids. In the dewatering method of dewatering while running along the dewatering member, the plurality of dewatering members are operated so that the pressing force against the paper raw material liquid is equal to or less than a set value, and the concentration of the paper raw material liquid is a target paper quality. The dewatering member disposed at a position having a predetermined concentration for obtaining the paper raw material liquid is further operated so that the pressing force on the paper raw material liquid becomes a predetermined pressing force for obtaining the desired paper quality, and the dewatering of the paper raw material liquid is performed. It is characterized by performing.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 8 show a control device for a dewatering member and a papermaking machine provided in a twin-wire former according to an embodiment of the present invention. It is a figure for explaining the dehydration method used. The dewatering member according to the present embodiment is mounted on, for example, a twin-wire former of a paper machine. For this reason, the twin-wire former will be described first, and then the control device of the dewatering member and the dewatering method used for papermaking, which are features of the present embodiment, will be described.

First, the twin-wire former is a former having a twin-wire portion, and is configured as described in the prior art (see FIGS. 9 and 10). That is, as shown in FIG. 9, the twin-wire former includes a head box 6, a top wire 1, and a bottom wire 2, and the top wire 1 and the bottom wire 2 each form a loop. And a gap (papermaking gap) 5 is formed between the bottom wire 2 and the bottom wire 2.
The paper raw material liquid 7 contained in the head box 6 is ejected from the head box 6 toward the paper making gap 5.

The top wire 1 is formed by a forming roll 3 and guide rolls 31A to 31D, and the bottom wire 2 is a breast roll 4, a suction coach roll 1
2 and are guided by guide rolls 32A to 32E and the like, and rotate to transfer the paper raw material liquid 7 in the gap 5 in a required direction (upward in FIG. 9). The paper raw material liquid 7 ejected from the head box 6 into the gap 5 is sandwiched in the gap 5 and dehydrated while moving at substantially the same speed as the wires 1 and 2 to form a paper layer. .

The gap 5 is gradually narrowed toward the downstream in the wire running direction, and the loops of the wires 1 and 2 at the upstream of the gap 5 are arranged in a curvature R shape. A first dewatering device 14, a second dewatering device 23, a third dewatering device 11, and a suction couching roll 12 are provided in this order from the upstream of the gap 5, and dewatering of the paper raw material liquid 7 and formation of a paper layer are performed. It has become.

Then, following the dewatering by the first dewatering device 14 and the second dewatering device 23, the third dewatering device 11 and the suction coach roll 12, which are provided in the loop of the bottom wire 2 and are also called a suction box, are operated by vacuum. The paper web 13 formed by the dewatering is transported onto the bottom wire 2 and transported to the next press part by a suction pickup roll (not shown).

In the present embodiment, as shown in FIG. 1, a second dehydrating device 23 is provided so as to face the papermaking gap 5 via the wire 1, and a second dehydrating device 23 is provided at the installation location of the second dehydrating device 23. The opposed dewatering device 15 is disposed so as to face the two dehydrating devices 23 with the papermaking gap 5 interposed therebetween. Here, the second dewatering device 23 is provided on the top wire 1 side, and the opposed dewatering device 15 is provided on the bottom wire 2 side.

Here, the second dewatering device 23 includes a plurality of dewatering blades (fixed dewatering blades, dewatering members) 20 which are installed on the device main body 23A at intervals. These dehydrating blades 20 are attached to the device main body 23A.
Of each dehydrating blade 20
Is configured as a wedge-shaped dewatering blade (hereinafter, referred to as a wedge-shaped dewatering blade) having a flat portion 20A and an inclined surface portion 20B.

The flat portion (hereinafter, simply referred to as a flat surface) 20A is provided in a loop of the top wire 1 so as to contact the top wire 1 to support the top wire 1. Inclined surface (hereinafter simply referred to as inclined surface)
20B is formed on the wire entry side (upstream in the wire running direction) with respect to the plane 20A, and is formed so as to be gradually separated from the top wire 1 toward the upstream side in the wire running direction.

Therefore, a wedge-shaped space (referred to as a wedge-shaped space) 20C is formed between the inclined surface 20B and the top wire 1. Note that the inclination angle θ of the inclined surface 20B is referred to as a wedge-angle. Here, the pressing force of these dewatering blades 20 is determined based on the tension of the wires 1 and 2, the radius of curvature of the wires 1 and 2 sandwiching the paper material liquid 7 at the position where the dewatering blades are disposed, and the mounting pitch of the dewatering blades. Is done.

As shown in FIG. 1, the opposed dewatering device 15
A plurality of (1 to N) dehydrating blades (opposing dehydrating blades, dehydrating members) 21 are provided on the device main body 15A at intervals. In FIG. 1, one dewatering blade 21 (NO.
1), second dehydrating blade 21 (NO. 2), third dehydrating blade 21 (NO. 3),..., N-th dehydrating blade 2
1 (NO.N).

These dewatering blades 21 press the bottom wire 2, and the pressing force of the dewatering blades 21 can be adjusted externally by fluid pressure during operation. Note that the dehydrating blade 21 is a movable dehydrating blade,
Also referred to as a flexible dewatering blade. For this reason, each dehydrating blade 21 is connected to the device body 15 via the base 22, the tube (elevating tube, operating tube) 24, and the support member 25.
Supported on A. Then, by adjusting the fluid pressure (for example, air pressure, oil pressure, etc.) in the tube 24, the pressing force of the dewatering blade 21 against the bottom wire 2 is adjusted, whereby the paper running between the wires 1 and 2 is adjusted. The dehydration is performed while the dehydration pressure generated in the raw material liquid 7 is adjusted.

Here, the dewatering blade 21 has a bottom wire contacting surface portion (hereinafter simply referred to as a contact surface) that contacts the bottom wire 2 and supports the bottom wire 2 on a surface on the bottom wire 2 side (this is referred to as an operation surface). 21A) is provided. A dovetail groove 21B having a T-shape is formed at the base end of the dewatering blade 21.
The dewatering blade 21 is integrally connected to the base 22 by fitting the distal end portion 22A of the base 22 to the base 22. By moving the dewatering blade 21 relative to the base 22 in the papermaking width direction, the dewatering blade 21 is
It can be inserted and removed with respect to.

Further, the base 22 is provided so as to be movable in a direction in which the base 22 can be separated from and brought into contact with the bottom wire 2 while being guided along the inner surface of a support member 25 protruding from the apparatus main body 15A. That is, the base 22 and the device body 15
A flexible tube (elevating tube, movable tube, rubber tube) 24 is interposed between A and A, and a fluid (air or oil) is supplied by a fluid pressure supply / discharge device (dehydration member operation adjusting device) 80. By adjusting the fluid pressure (for example, air pressure or hydraulic pressure) inside the tube 24 by supplying and discharging, the internal pressure state of the tube 24 is adjusted to adjust the degree of pressure contact of the tube 24 with the base 22, thereby , The base 22 can be moved in a direction in which the base 22 can be separated from and brought into contact with the bottom wire 2.

For example, when the internal pressure of the tube 24 increases, the tube 24 is pressed against the base 22 while the base 22 is separated from the apparatus main body 15A, that is, the base 22 is moved in If it moves in the direction approaching the line and the internal pressure of the tube 24 decreases, the pressure contact of the tube 24 to the base 22 is weakened, and the base 22 is moved in the direction approaching the device body 15A, that is, the base 22 is The paper raw material liquid 7 moves in a direction away from the traveling line.

When the base 22 moves in the direction in which the base material liquid 7 moves away from and comes into contact with the traveling line of the paper material liquid 7, the dehydrating blade 21 also moves accordingly, so that the pressing force acting on the paper material liquid 7 is adjusted. Will be done. For this reason, the pressing force adjusting mechanism is constituted by the base 22 movable with respect to the device main body 15A, the extendable tube 24, and the fluid pressure supply / discharge device 80 for adjusting the internal pressure of the tube 24. .

When the concentration (raw material concentration, mat concentration) of the paper raw material liquid 7 between the two wires 1 and 2 is within a predetermined concentration range in which a desired paper quality can be obtained, the paper is pressed with a predetermined pressing force. By adjusting the pressing force of the dehydrating blade as described above, it was found that the fiber dispersion of the paper raw material liquid 7 could be kept good and the quality of the paper could be kept good. For this reason, in order to adjust the pressing force of the dewatering blade so as to be pressed with a predetermined pressing force when the concentration of the paper raw material liquid 7 is within a predetermined concentration range in which a desired paper quality can be obtained, the twin according to the present embodiment is used. As shown in FIG. 1, the wire former is provided with an impedance meter 50, an input device 51, and a controller 70 for the dewatering blade 21 including a controller 52.
Then, the paper raw material liquid 7 is measured by the impedance meter 50.
Is measured, and the pressing force of each dehydrating blade 21 can be adjusted based on the measured impedance.

Here, as shown in FIGS. 2 and 3, the impedance meter 50 includes two electrodes 61A and 61B attached to the contact surfaces (wire contact surfaces, blade surfaces) 21A of the dewatering blades 21, respectively. These electrodes 61
A switch (multiplexer) 62 to which one electrode 61A of the electrodes 61A and 61B is connected,
Detector 63 to which other electrode 61B of 1B is connected
And is provided.

Then, each dehydrating blade 21 and the detector 63
Are sequentially switched by the switch 62 while detecting the impedance of the paper raw material liquid (pulp suspension) 7 interposed between the electrodes 61A and 61B by the detector 63. , 61B, the impedance of the paper raw material liquid 7 traveling at the position where the dewatering blade 21 is disposed is measured.

Here, first, the switch 62 is switched to an electric circuit connecting the first dehydrating blade 21 (NO. 1) and the detector 63, and the first dehydrating blade 21 (NO. 1) is switched.
The impedance of the paper material liquid 7 interposed between the electrodes 61A and 61B attached to 1) is detected by the detector 63. Thus, the impedance of the paper raw material liquid 7 traveling at the position where the first dewatering blade 21 (NO. 1) is disposed is measured.

Next, a switch 62 is used to switch to an electric circuit connecting the second dehydrating blade 21 (NO. 2) and the detector 63, and the electrodes 61A, 61A, The impedance of the paper material liquid 7 interposed between 61B is detected by the detector 63. Thereby, the impedance of the paper raw material liquid 7 traveling at the position where the second dewatering blade 21 (NO. 2) is disposed is measured.

Next, the switch 62 switches to an electric circuit connecting the third dehydrating blade 21 (NO. 3) and the detector 63, and the electrodes 61A and 61B attached to the third dehydrating blade 21 (NO. 3). Paper raw material liquid 7 interposed
Is detected by the detector 63. Thereby, the impedance of the paper raw material liquid 7 traveling at the position where the third dewatering blade 21 (NO. 3) is disposed is measured.

Similarly, from the upstream side in the wire running direction to the N-th dehydrating blade 21 (NO.
The impedance of the paper raw material liquid 7 is detected in order, whereby the impedance of the paper raw material liquid 7 up to the position where the Nth dehydrating blade 21 (NO.N) is disposed is measured in order.
In this way, the impedance of the paper raw material liquid 7 traveling at each location of each dewatering blade 21 arranged in order from the upstream side in the wire traveling direction is measured in order.

The impedance meter 50 is connected to the control means 52, and the impedance of the paper stock solution 7 running at the position where each dewatering blade 21 is disposed measured by the impedance meter 50 is transmitted to the control means 52. It is to be sent. Control means 52
Is based on the impedance of the paper raw material liquid 7 measured by the impedance meter 50 in order to maintain the fiber dispersion of the paper raw material liquid 7 and adjust the pressing force by the dewatering blade 21 to maintain the quality of the paper good. Thus, the amount of movement of the dewatering blade 21 is controlled.

For this purpose, as shown in FIG. 1, the control means 52 comprises a conversion table creating means 53, a dewatering blade determining means 54, and a dewatering blade operation control means 55. Among them, the conversion table creation means 53
Impedance meter 5 constituting the above-mentioned concentration estimating means
The conversion table (concentration-dewatering blade conversion table) is created by associating the concentration of the paper raw material liquid 7 estimated based on the impedance of the paper raw material liquid 7 measured with 0 with the plurality of dehydrating blades 21. .

That is, first, the conversion table creation means 52
Since the impedance of the paper stock solution 7 measured by the impedance meter 50 is correlated with the amount of water in the paper stock solution 7 traveling between the wires 1 and 2, the impedance and the wire shown in FIG. Using a map showing the relationship between the thickness between the wires 1 and 2 (corresponding to the thickness of the paper raw material liquid 7), the thickness between the wires 1 and 2 according to the impedance Z measured by the impedance meter 50 ( The thickness (t) of the paper raw material liquid is estimated.

Here, the relationship between the thickness t (m) between the wires and the impedance Z (kΩ) is expressed by the following equation (1). Here, α is a constant. t = α / Z (1) Next, the conversion table creating means 53 calculates the concentration of the paper raw material liquid 7 from the thickness t of the paper raw material liquid 7 obtained using a map as shown in FIG. Raw material concentration, mat concentration).

Here, first, the conversion table creation means 5
3 is the basis weight a (kg / m ² ) of the paper to be made and the paper width l
(M), the papermaking speed (the length of the sheet-shaped paper raw material liquid traveling per unit time) v (m / s), and multiplying by the raw material weight (the sheet-shaped paper raw material liquid traveling per unit time). Weight) alv (kg / s) is estimated. Further, the thickness between wires (the thickness of the paper raw material liquid) t (m) and the papermaking speed (the length of the sheet-shaped paper raw material liquid traveling per unit time) v (m /
s) is multiplied by the paper width l (m) to obtain a raw material volume (volume of a sheet-shaped paper raw material liquid traveling per unit time) tlv
(= Αlv / Z) is estimated.

Then, the raw material concentration D of the paper raw material liquid 7 is estimated by dividing the raw material weight alv by the raw material volume αlv / Z according to the following equation. D = alv / (αlv / Z) = aZ / α For this reason, the conversion table creating means 53 includes the input device 5
1, the basis weight a (kg / m ² ) and width l of the paper to be made
(M), and the papermaking speed (length of the sheet-shaped paper raw material liquid traveling per unit time) v (m / s) are input.

The conversion table creating means 53 estimates the concentration of the paper raw material liquid 7 running at the position where each dewatering blade 21 is disposed in this way, and uses this concentration for each dewatering blade 21.
Are plotted in correspondence with the arrangement position (dehydration blade number) of the above, whereby a conversion table (concentration-dehydration blade conversion table) as shown in FIG. 5 is created.

Here, since the impedance used for calculating the concentration of the paper raw material liquid 7 changes according to the paper making speed, the concentration of the paper raw material liquid 7 also differs according to the paper making speed. Therefore, FIG. 5 shows a case where the paper making speed is 500 mpm and a case where the paper making speed is 100 mpm.
The case of 0 mpm is illustrated. The function of estimating the concentration of the paper stock solution 7 of the conversion table creation means 53 and the above-described impedance meter 50 indicate that the paper stock solution 7 traveling along the plurality of dehydrating blades 21 is upstream to downstream in the running direction. Concentration estimating means for estimating the concentration of the paper raw material liquid 7 at a plurality of locations is provided.

The dehydrating blade determining means (dehydrating member determining means) 54, as shown in FIG. 6, converts the conversion table generated by the conversion table generating section 53 based on the predetermined density input via the input device 51. The purpose of the present invention is to determine a dehydrating blade 21 to be operated in accordance with a predetermined density at which desired paper quality can be obtained using a table. That is, the dehydrating blade determining means 54 uses the conversion table to convert the paper
Is determined as a dewatering blade that operates the dewatering blade 21 disposed at a location where the concentration of the toner is within a predetermined concentration range. In addition, as shown in FIG. 6, here, the seventh and eighth dehydrating blades are determined as the dehydrating blades to be operated.

Here, the predetermined concentration is set as a paper raw material liquid concentration of about 1 to 2% as shown by hatching in FIG.
This is because, when the concentration of the paper raw material liquid 7 is within the range of about 1 to 2%, the fiber dispersion in the paper raw material liquid 7 can be kept good by applying a predetermined pressing force by the dewatering blade 21. This is because the quality of the paper to be made can be improved. Here, the predetermined concentration is input by the input device 51, but may be stored in the dewatering blade determination unit 54 in advance.

In this case, the dehydrating blade 21 is determined using the conversion table. However, the dehydrating blade determining means 54 determines whether the concentration of the paper raw material liquid 7 estimated by the above-described concentration estimating means is the target paper quality. The dewatering blade 21 disposed at a position where the concentration is obtained to obtain the predetermined value may be determined as the working dewatering blade. For example,
The dewatering blade determining means 54 is connected to the impedance meter 5
Density determining means for determining whether or not the respective densities estimated by the density estimating means composed of 0 and the conversion table creating means 53 have reached a predetermined density. The density determining means reduces the estimated density to a predetermined density. It is also possible to adopt a configuration in which the dewatering blade 21 disposed at the position determined to be in operation is determined as the working dewatering blade.

The dewatering blade operation control means (dewatering member operation control means) 55 sends an operation signal (control signal) to a fluid pressure supply / discharge device 80 which supplies and discharges fluid to and from the dehydration blade 21 determined by the dehydration blade determination means 54. ) Is output. That is, the dehydrating blade operation control means 55 adjusts the pressing force of the working dewatering blade 21 determined by the dewatering blade determining means 54 to a predetermined pressing force. An operation signal (control signal) is output to the supply / discharge device 80.

In this case, the optimum pressing force (predetermined pressing force) when the paper raw material liquid 7 is pressed by the dehydrating blade 21 at a concentration within the above-mentioned predetermined concentration range (within a range of about 1 to 2%) is The input device 51 is determined by conducting a test in advance.
Is to be entered via For example, in order to press the dewatering blade 21 at a concentration of the paper raw material liquid 7 within a range of about 1 to 2% to produce high-quality paper, the pressing force of the dewatering blade 21 is limited by the blade width of the dewatering blade 21. Is set to about 39.2 kPa to about 58.8 kPa when the pressure is about 1 cm (that is, about 400 to 600 g / cm ² when the blade width is about 1 cm). Is preferred. Here, the predetermined pressing force is input by the input device 51, but may be stored in the dewatering blade operation control means 55 in advance.

As described above, the dewatering blade determining means 54
Is adjusted so that the pressing force on the paper raw material liquid 7 becomes a predetermined pressing force for obtaining the target paper quality, but in the present embodiment, the pressing force on the dewatering blade 21 is further determined in the present embodiment. The pressing force of the dewatering blade 21 other than the dewatering blade 21 determined by the means 54 is adjusted so as to be equal to or less than a set value. Thereby, the pressing force by the other dewatering blades 21 is lower than that of the prior art, and the friction between the dewatering blade 21 and the wires 1 and 2 is reduced as a whole, and the amount of wear of the wires 1 and 2 is reduced. I try to reduce it.

Here, the set value is set so that the pressing force of the dewatering blade 21 other than the dewatering blade 21 determined by the dewatering blade determining means 54 becomes a pressing force enough to dewater the paper raw material liquid 7. Is set. Here, at least the pressing force of the other dewatering blade 21 is set to be lower than the pressing force of the conventional dewatering blade.

Specifically, first, a plurality of dewatering blades 21
Are operated so that the pressing force against the paper raw material liquid 7 is equal to or less than a set value, and the pressing force by the dewatering blade 21 determined by the dewatering blade determining means 54 is determined to be a predetermined pressing force. The dewatering blade 21 is further operated to dewater the paper raw material liquid 7. Here, in order to reduce the abrasion amount of the wires 1 and 2, the pressing force of the dewatering blade 21 other than the determined dewatering blade 21 is adjusted to a set value or less. In order to improve the dispersibility of the fibers and to form paper having excellent formation, the pressing force of the dewatering blade 21 determined by the dewatering blade determining means 54 as described above is adjusted to a predetermined pressing force. Just do
It is not always necessary to adjust the pressing force by the other dehydrating blades 21 to a set value or less. For this reason, the pressing force by the other dehydrating blades 21 may be adjusted so as to be an arbitrary pressing force. For example, the pressing force by the other dehydrating blades 21 may be adjusted in the same manner as in the prior art.

When the wires 1 and 2 running across the paper material liquid 7 are arranged so as to have a radius of curvature R, the paper material liquid can be applied without the pressing force of each dewatering blade 21 acting. 7 can be dehydrated, the electrodes 61A, 61B
By simply contacting the contact surface 21A of each dewatering blade 21 with the paper raw material liquid 7 so that the impedance of the paper raw material liquid 7 can be detected using It can be adjusted so that it does not work.

The control device for the dewatering member provided in the twin-wire former as one embodiment of the present invention is configured as described above, and the control of the dewatering blade (dewatering method used for papermaking) by this device is as follows. Can be performed. First, a procedure for creating a conversion table by the conversion table creating means 52 will be described.

That is, as shown in the flowchart of FIG. 7, in step S10, the basis weights a,
A paper width 1 and a papermaking speed (length) v are input. Next, in step S20, the impedances Z measured by the impedance meters 50 disposed at a plurality of locations from the upstream side to the downstream side in the traveling direction of the paper raw material liquid 7 are respectively read.

Then, in step S30, control means 52
Is used to estimate the concentration (raw material concentration, mat concentration) of the paper raw material liquid 7 traveling at the position where each dewatering blade 21 is disposed, using the input basis weight, width, length and the read impedance Z. That is, first, the impedance Z measured by the impedance meter 50 using a map showing the relationship between the impedance as shown in FIG. 4 and the thickness between the wires 1 and 2 (corresponding to the thickness of the paper stock solution 7). The thickness (the thickness of the paper raw material liquid) t between the wires 1 and 2 is estimated according to.

Next, the basis weight a of the paper to be made, the paper width l, and the papermaking speed (the length of the sheet-shaped paper raw material liquid running per unit time) v are multiplied by the raw material weight (running per unit time). (Weight of the sheet-shaped paper raw material liquid) alv is estimated. Further, the thickness between the wires (the thickness of the paper stock solution) t, the papermaking speed (the length of the sheet-like paper stock solution running per unit time) v, and the paper width 1 are multiplied to obtain the material volume ( Volume of sheet-shaped paper raw material liquid running per unit time) tlv (=
αlv / Z).

The raw material concentration D of the paper raw material liquid 7 is estimated by dividing the raw material weight alv by the raw material volume αlv / Z according to the following equation. D = alv / (αlv / Z) = aZ / α Next, in step S40, it is determined whether or not the concentration of the paper raw material liquid 7 has been estimated at the positions where all the dewatering blades 21 are disposed. When it is determined that it is estimated at the disposition position, the process proceeds to step S50, and the conversion is performed by plotting the concentration of the paper raw material liquid 7 at the disposition position of each dewatering blade 21 in association with each dehydration blade 21 disposition position. A table (concentration-dehydration blade conversion table) is created.

On the other hand, if it is determined in step S40 that the calculation has not been performed at all the disposition positions of the dewatering blades 21, the process returns to step S20, and the processing from step S20 to step S40 is repeated. Next, a control procedure by the dehydrating blade determining means 53 will be described. That is, first, in step A10, a predetermined density (for example, about 1-2
%), A predetermined pressing force applied to the paper raw material liquid 7 at this predetermined concentration is input.

Next, in step A20, the dehydrating blade 21 disposed at the place where the concentration of the paper raw material liquid 7 has a predetermined concentration is operated using the conversion table created by the conversion table creating means 53. The dewatering blade 21 is determined. Then, in step S30, an operation signal is output to the fluid pressure supply / discharge device 80 that supplies / discharges the fluid to / from the determined dewatering blade 21. As a result, the wire 1,
The depressing blade 21 operates so that the pressing force on the paper material liquid 7 by the dehydrating blade 21 becomes a predetermined pressing force in a portion where the concentration of the running paper material liquid 7 is sandwiched between the two.
Is dehydrated.

The control of the dewatering blade 21 determined by the dewatering blade determining means 53 is performed as described above. In the present embodiment, the premise is that a plurality of dewatering blades 21 are first used as paper material liquids. 7 is operated so that the pressing force to 7 becomes equal to or less than the set value. Then, the dewatering blade 21 determined so that the pressing force of the dewatering blade 21 determined by the dewatering blade determining means 54 becomes a predetermined pressing force is further operated to dewater the paper raw material liquid 7.

Therefore, according to the control device for the dewatering member according to the present embodiment, the dewatering blade 21 disposed at the position where the concentration of the paper raw material liquid 7 is at the predetermined concentration is determined as the working dewatering blade, and is determined. The dewatering blade 21 is operated so that the pressing force on the paper raw material liquid 7 becomes a predetermined pressing force, so that the paper raw material liquid 7 is dehydrated.
By generating an appropriate internal pressure in the paper raw material liquid 7 according to the concentration of the paper raw material 7, there is an advantage that the dispersibility of the fibers of the paper raw material liquid 7 is improved, and a paper excellent in formation can be formed.

Further, the plurality of dehydrating blades 21 are operated so that the pressing force on the paper raw material liquid 7 becomes equal to or less than a set value, and the concentration of the paper raw material liquid 7 becomes a predetermined concentration capable of obtaining a target paper quality. Dewatering blade 21 disposed at the position
Is further operated so that the pressing force on the paper raw material liquid 7 becomes a predetermined pressing force for obtaining the desired paper quality, and the paper raw material liquid 7 is dehydrated. An internal pressure can be generated in the paper raw material liquid 7,
Has the advantage of improving the dispersibility of the fibers and making paper with excellent formation. In addition, the friction between the dewatering blade 21 and the wire 2 and the friction between the dewatering blade 20 and the wire 1 are reduced as a whole. Can reduce the wires 1,2
There is an advantage that the wear amount of the wires 1 and 2 can be reduced and the life of the wires 1 and 2 can be extended. Also, by extending the life of the wires 1 and 2, the frequency of replacement of the wires 1 and 2 is reduced, and the time for stopping the machine at the time of wire replacement is reduced. Thereby, there is an advantage that the operation rate of the machine is improved and the production efficiency is improved.

Further, the operating dewatering blade 21 is operated in accordance with a predetermined density by using one of a plurality of density-dewatering member conversion tables prepared in advance for each paper making speed provided in the dewatering blade determining means 54. Since the conversion table need not be created each time the machine is actually operated, the control of the dewatering blade 21 can be simplified, and the time required for the control can be shortened. There is also an advantage that control delay can be prevented.

Since the concentration of the paper raw material liquid 7 is estimated based on the thickness and the basis weight of the paper raw material liquid 7 by the concentration estimating means having the impedance meter 50, the concentration of the paper raw material liquid 7 can be easily estimated. There is also an advantage that. Further, since the thickness of the paper raw material liquid 7 is obtained from the impedance of the paper raw material liquid 7, there is an advantage that the concentration of the paper raw material liquid 7 can be more easily estimated.

In the above embodiment, the impedance meter 5 is provided only on the wire contact surface of each movable dehydrating blade.
0 electrodes 61A and 61B are attached.
The mounting positions of A and 61B are not limited to these,
Further, it may be attached to the wire contact surface of each fixed type dewatering blade, or may be attached only to the wire contact surface of each fixed type dewatering blade.

Further, even in the case of disposing it on the movable dehydrating blade or the fixed dehydrating blade, it is not always necessary to dispose it on all the dehydrating blades. good. Further, here, the electrodes 61A and 61B of the impedance meter 50 are attached to the wire contact surface of the dehydrating blade. However, the electrodes 61A and 61B of the impedance meter 50 may be configured to contact the wire. You may make it attach. When the electrode mounting member is separately provided in this manner, the dewatering device does not need to be provided with a dewatering blade. For example, the paper raw material liquid 7 traveling between the wires is pressed by a roll-shaped member (dewatering roll). May be configured.

In the above-described embodiment, a conversion table is created when a machine is operated to make paper, and a dehydrating blade to be operated is determined using the created conversion table. A plurality of conversion tables (concentration-dewatering member conversion tables) are created for each papermaking speed, basis weight, and paper width, and these are converted into a database and stored, and the conversion table stored in this database is used in accordance with a predetermined density. The operating dewatering blade may be determined in such a manner.

In the above-described embodiment, the paper stock liquid 7 travels between the plurality of dewatering blades 20 provided in the second dewatering device 23 and the plurality of dewatering blades 21 provided in the opposed dewatering device 15. In addition, the dewatering blade is operated in accordance with the concentration of the paper raw material liquid, but is not limited to this, and other dewatering devices provided in the twin-wire former (for example, the first dewatering device and the third dewatering device) machine)
The dewatering blade may be operated according to the concentration of the paper raw material liquid when the paper raw material liquid 7 travels on the portion where the dewatering member is provided. In this case, the concentration of the paper raw material liquid and the pressing force applied to the paper raw material liquid for obtaining the desired paper quality differ depending on the disposition position of the dewatering device (that is, the dewatering state of the paper raw material liquid). Must be set in accordance with the arrangement position (that is, the dehydration state of the paper raw material liquid).

[0078]

As described in detail above, according to the dewatering method used for papermaking according to the first and second aspects of the present invention, the dewatering method provided at a position where the concentration of the paper raw material liquid is at a predetermined concentration. The member is determined as an operation dewatering member, and the determined dewatering member is operated so that the pressing force against the paper raw material liquid is a predetermined pressing force to perform dehydration of the paper raw material liquid, thereby reducing the concentration of the paper raw material liquid. By generating an appropriate internal pressure in the paper raw material liquid, the dispersibility of the fibers in the paper raw material liquid is improved, and there is an advantage that paper excellent in formation can be formed.

According to the dewatering member control device provided in the twin wire former according to the third and fourth aspects of the present invention, the dewatering member disposed at a position where the concentration of the paper raw material liquid is at a predetermined concentration is actuated. It is determined as a dewatering member, and the determined dewatering member is operated so that the pressing force on the paper raw material liquid becomes a predetermined pressing force so as to perform dehydration of the paper raw material liquid. By generating an appropriate internal pressure in the paper raw material liquid, there is an advantage that the dispersibility of the fibers in the paper raw material liquid is improved, and paper excellent in formation can be formed.

According to the dewatering member control device provided in the twin wire former of the present invention, a plurality of density-dewatering member conversion tables prepared for each paper making speed provided in the dewatering member determining means are provided. The operating dewatering member is determined according to the predetermined concentration by using one of the conversion tables, and it is not necessary to create the conversion table every time the machine is actually operated, so the control of the dewatering member And the control time can be shortened, and control delay can be prevented.

According to the dewatering member control device provided in the twin wire former of the present invention, the concentration of the paper raw material liquid is estimated by the concentration estimating means based on the thickness and basis weight of the paper raw material liquid. Therefore, there is an advantage that the concentration of the paper raw material liquid can be easily estimated. According to the dewatering member control device provided in the twin wire former of the present invention, the thickness of the paper raw material liquid is obtained from the impedance of the paper raw material liquid by the concentration estimating means. Has the advantage that it can be performed more easily.

According to the dewatering method of the present invention for papermaking according to the present invention, the plurality of dewatering members are operated so that the pressing force against the paper raw material liquid is equal to or less than a set value, and the concentration of the paper raw material liquid is reduced. The dewatering member disposed at a position where the desired paper quality is obtained at a predetermined concentration is further operated so that the pressing force on the paper raw material liquid becomes a predetermined pressing force capable of obtaining the desired paper quality. Since the paper raw material liquid is dehydrated, an appropriate internal pressure can be generated in the paper raw material liquid according to the concentration of the paper raw material liquid. And the friction between the dewatering member and the wire can be reduced as a whole,
Thus, there is also an advantage that the amount of wear of the wire can be reduced and the life of the wire can be extended. Further, by extending the life of the wire, the frequency of wire replacement is reduced, and the time for stopping the machine at the time of wire replacement is reduced. Thereby, there is an advantage that the operation rate of the machine is improved and the production efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an entire configuration of a dewatering member control device provided in a twin-wire former according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining an electrode mounting position of an impedance meter provided in a control device of a dehydrating member provided in the twin wire former according to one embodiment of the present invention.

FIG. 3 is a schematic diagram showing an impedance meter provided in a dewatering member control device provided in the twin wire former according to one embodiment of the present invention.

FIG. 4 is a diagram for explaining a conversion table creating means provided in the control device of the dewatering member provided in the twin wire former according to one embodiment of the present invention.

FIG. 5 is a diagram showing a conversion table created by a conversion table creating unit provided in a control device for a dewatering member provided in the twin-wire former according to one embodiment of the present invention.

FIG. 6 is a diagram for explaining a dewatering member determining means provided in the dewatering member control device provided in the twin wire former according to one embodiment of the present invention.

FIG. 7 is a flowchart for explaining a conversion table creation method (a dehydration method used for papermaking) by a conversion table creation unit provided in a dewatering member control device provided in the twin wire former according to one embodiment of the present invention. .

FIG. 8 is a flowchart for explaining a dewatering member determining method (a dewatering method used for papermaking) by a dewatering member determining means included in a dewatering member control device included in the twin-wire former according to one embodiment of the present invention. .

FIG. 9 is a schematic configuration diagram illustrating a configuration example of a conventional twin-wire former.

FIG. 10 is a schematic cross-sectional view showing a conventional twin-wire former dehydrator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Top wire 2 Bottom wire 3 Forming roll 4 Breast roll 5 Gap (gap for papermaking) 6 Head box 7 Paper raw material 9 Dehydration blade 12 Suction cutch roll 13 Sheet of paper 14 First dehydration equipment 15 Opposing dehydration equipment 15A Base 20 Dehydration blade (Fixed dewatering blade) 21 Dewatering blade (opposing dewatering blade) 20A Flat surface part 20B Inclined surface part 20C Wedge-shaped space (wedge-shaped space) 21A Bottom wire contact surface part 21B Dove groove 22 Base 22A Tip part 23 Opposing dewatering equipment 23A Dewatering equipment Main body 23B Mounting part 24 Tube 25 Support member 50 Impedance meter 51 Input device (input means) 52 Control device 53 Conversion table creation means 54 Dehydration blade determination means (Dehydration member determination means) 55 Dehydration break Operation control means (dehydrated member operation control means) 61A, 61B electrode 62 switcher 63 detector 70 control device 80 a fluid pressure feed and discharge device

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuhiko Masuda 5007 Itozakicho, Mihara City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Mihara Works F-term (reference) 4L055 CE60 DA15 DA25 DA27 DA29 DA33 FA08 FA09

Claims (8)

[Claims] 1. A dewatering method in which a paper material liquid is sandwiched in a papermaking gap formed between two wires forming a loop, the wires are operated, and the paper material liquid is dewatered while traveling along a plurality of dewatering members. In the method, a predetermined concentration for obtaining a target paper quality and a predetermined pressing force to be applied to the paper raw material liquid are set, and the concentrations of the paper raw material liquid at a plurality of locations from upstream to downstream in the running direction of the paper raw liquid are set. The dewatering member disposed at the position where the estimated concentration is the predetermined concentration is determined as the working dewatering member, and the pressing force of the determined dewatering member against the paper raw material liquid is the predetermined pressing force. A dewatering method for use in papermaking, characterized in that the paper raw material liquid is dewatered by operating as follows. 2. A dewatering method in which a paper material liquid is sandwiched in a papermaking gap formed between two wires forming a loop, the wires are operated, and the paper material liquid is dewatered while running along a plurality of dewatering members. In the method, the concentration of the paper raw material liquid is estimated at a plurality of locations from the upstream side to the downstream side in the traveling direction of the paper raw material liquid, and the estimated concentrations are associated with the arrangement positions of the plurality of dewatering members. A conversion table for the density-dewatering member, and determines a dehydration member to be operated in accordance with a predetermined density that can obtain a desired paper quality using the conversion table thus prepared. A dehydration method used for papermaking, comprising dehydrating a liquid. 3. A twin-wire former in which a papermaking gap is formed between two wires forming a loop, and a paper raw material liquid is sandwiched between the papermaking gaps, the wires are operated, and the paper raw material liquid is dewatered while running. In the dewatering member control device for controlling the plurality of dewatering members provided in the, the concentration of the paper raw material liquid at a plurality of locations ranging from upstream to downstream in the traveling direction of the paper raw material liquid traveling along the plurality of dewatering members A concentration estimating means for estimating each, and the dewatering member disposed at a position where the concentration of the paper raw material liquid estimated by the concentration estimating means is a predetermined concentration capable of obtaining a desired paper quality, as an operating dewatering member A dehydrating member determining means for determining, and a dehydrating member operation controlling means for outputting a control signal to operate the operating dehydrating member determined by the dehydrating member determining means. Control device for a dewatering member provided in a twin-wire former. 4. A twin-wire former in which a papermaking gap is formed between two wires forming a loop, and a paper raw material liquid is sandwiched in the papermaking gap to operate the wires to dewater while running the paper raw material liquid. In the dewatering member control device for controlling the plurality of dewatering members provided in the, the concentration of the paper raw material liquid at a plurality of locations from the upstream to the downstream in the traveling direction of the paper raw material liquid running along the plurality of dewatering members Density estimating means for estimating each of them; conversion table creating means for creating a concentration-dehydrating member conversion table by associating each of the densities estimated by the concentration estimating means with the plurality of dehydrating members; A dehydrating member determining means for determining a dehydrating member to be activated in accordance with a predetermined density capable of obtaining a target paper quality using the conversion table created by Characterized in that it comprises a dewatering member operation control means for outputting a control signal to actuate the the acting dynamic dewatering member which is determined by the wood determining means, the control device of the dewatering member provided to a twin wire former. 5. The dewatering member determining means includes a plurality of density-dewatering member conversion tables prepared in advance for each papermaking speed, and the predetermined density is determined using one of the plurality of conversion tables. The control device for a dewatering member provided in the twin-wire former according to claim 3, wherein the operating dewatering member is determined according to the following. 6. The method according to claim 3, wherein said concentration estimating means estimates the concentration of said paper raw material liquid based on the thickness and basis weight of said paper raw material liquid. A control device for a dewatering member provided in the twin-wire former described in the above. 7. The control device for a dewatering member provided in a twin-wire former according to claim 6, wherein said concentration estimating means obtains the thickness of said paper raw material liquid from the impedance of said paper raw material liquid. 8. A dewatering method in which a paper material liquid is sandwiched in a papermaking gap formed between two wires forming a loop, the wires are operated, and the paper material liquid is dewatered while traveling along a plurality of dewatering members. In the method, all of the plurality of dewatering members are operated such that the pressing force on the paper raw material liquid is equal to or less than a set value, and the concentration of the paper raw material liquid is a predetermined concentration that can obtain a desired paper quality. The dewatering member disposed at the position is further operated so that the pressing force on the paper raw material liquid becomes a predetermined pressing force for obtaining a desired paper quality, thereby dewatering the paper raw material liquid. Dewatering method used for papermaking.