JP3272483B2 - Paper layer forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for forming a paper layer of a papermaking machine.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIG. FIG. 2 is a diagram of a conventional multilayer forming apparatus including a long net and a short net.
This apparatus is a wet end of a paper machine called a typical multiformer, which is composed of a long net portion and a short net portion and performs a paper making operation. Head box 24, 24a for both long net and short net
The raw material liquid ejected from is dehydrated by the table devices 20 and 20a to form a paper layer. The paper layer formed by the short net portion travels on the short net whose direction is changed downward by the suction coach roll 12c, and is further turned by the dandy roll 26 in the traveling direction of the long net 17, and at the same time, the paper layer is formed. It is pressed against the raw material mat on the net.

Accordingly, two layers of wet paper are laminated while the raw material mat on the long net is redispersed by the short net portion dandy roll 26. The laminated multi-layered paper is further dewatered by a suction box 21 provided in a fourdrinier loop and sent to a press part, which is the next step, by a suction pickup roll 23a.

[0004]

The prior art has the following disadvantages. (1) Since each paper layer is composed of the table equipment 20, 20a to the usual forming board, foil, table roll, and wet box, the formation is not good. (2) Since it is necessary to increase the density of the paper layer of the long net portion to such a degree that the paper layer of the short net portion is not broken at the dandy roll 26 where the paper layer of the short net portion is formed, the length from the pre-roll 19 to the dandy roll 26 is increased. It is necessary to increase the length of the net. In addition, since dry-on-dry lamination is performed, the internal strength (adhesion strength between layers) is low.

(3) In the case where the short net portion is one unit and the intermediate layer is made of three layers of a white plate using a cheap raw material such as waste paper, the head net 24 for the long net is made of two layers. Since the length of the long net portion that can be dehydrated is long, the two layers are easily mixed and the purity is difficult to maintain. (The term "purity" as used herein refers to the degree to which the different kinds of raw materials are not mixed when the different kinds of raw materials in each layer are mixed together. In the case of making a white board, the virgin raw material having high whiteness is generally placed on the net side (outside). An intermediate layer such as a waste paper material is flowed over the intermediate layer so that the raw material of the intermediate layer may be seen outside the white material. An object of the present invention is to provide a paper layer forming apparatus which solves the problems, has good formation of each layer, has a high internal strength, and easily maintains purity.

[0006]

According to the present invention, a dewatered paper layer that has been dewatered by a table device installed in a second wire loop is combined with a paper layer that has been initially dewatered in a first wire loop. In the paper layer forming apparatus configured to perform the lamination by the wire loop, the paper traveling on the first wire loop is provided on the downstream side of the lamination section of the first wire loop. and forming means for bettering formation of the paper layer by applying a pulse pressure in the layer, the vacuum suction
Paper layer and a suction means allowed to increase the concentration of the paper layer Ri
It is characterized by being provided continuously in the flow direction .

[0007]

[Action]

(1) The joining side (usually poor formation) of the paper layer formed on the top wire unit comes into contact with the raw material liquid (having a lower concentration than the conventional joining part) on the bottom wire unit. The concentration decreases as you run. Thereafter, when a strong pressure pulse is received by the second forming shoe 8 part, it is redistributed and the formation is improved, and at the same time, the internal strength of the mixing part is increased by the mixing effect. On the other hand, the paper layer formed on the bottom wire side (the material is well dispersed because of the agitation effect of the table equipment while the raw material concentration is low) has a considerably high concentration, and the paper layer network is strong. Purity is maintained because the network is not broken and there is no mixing.

(2) A dewatering device provided in the bottom wire loop at a portion where the top wire engages with the bottom wire (for example, the first dewatering device described in Japanese Patent Application No. 02-403649 "Twin Wire Former of Paper Machine"). Since the fixed dewatering device such as the forming shoe 7 has a large radius of curvature that is convex upward, the pressing force of the top wire at the laminating portion is small and the vacuum (natural leg or externally applied) sucks the lower portion. Since the dewatering to water is promoted, the raw material swallowing performance on the bottom wire is good, and the low basis weight is high (220 gr / m ² , about 6
Even at 0 m / min, no trouble such as swallowing was observed without any problem). (3) The problem of purity when a two-layer primary head box is used in three-layer whiteboard production is that the initial dewatering section from the slice lip, which is the raw material ejection port, to the lamination section is short, and the raw material liquid is short. Is sufficiently and slightly improved.

(4) Since the dewatering device provided above the top wire loop is arranged without wrapping with the wire running substantially horizontally, the sliding resistance is low and the problem of wire abrasion and the like can be avoided even if the raw material is not flowed. Absent. Therefore, a single-layer making operation using only the primary head box 5 without flowing the raw material from the secondary head box 5a is possible. In this case, the dehydrating equipment provided in the twin section, the first forming shoe 7, the second forming shoe 8, the low vacuum suction box 9, and the transfer box 10 have sufficient dewatering ability, and the leading blade of the forming board 6 is applied. By using a wide blade having a curvature described in JP-A-02-403649, the raw material jet can be smoothly landed and high-speed operation is possible.

[0010]

An embodiment according to the present invention will be described with reference to FIG. FIG. 1 is a front view of the paper layer forming apparatus of the embodiment. In the figure, reference numeral 2 denotes a top wire loop, and 1 denotes a bottom wire loop, which is configured as a twin wire former having a band in which a raw material is inserted between the loops and runs. 6 is a forming board, 7 is a first forming shoe, 9 is a low vacuum suction box, 10 is a transfer box, 11
What are Re also Haise bottom wire loop 1 in a high vacuum suction box. 4 is the top wire loop
2 is a forming roll disposed at a portion where the bottom wire loop 1 and the bottom wire loop 1 are combined . 8 is a second forming shoe which is the top wire loop of the bottom wire loop 1.
Of the forming roll 4 which is a part where the
It is located at the downstream site . The dehydrator is disclosed in Japanese Patent Application
2-403649 "Dewatering machine as described in" Twin Wire Former of Paper Machine "and the primary head box 5
A pulse pressure is applied to the raw material liquid ejected from to promote fiber dispersion and dewater through both wires to form a paper layer.

The upper surface of the top wire loop 2 travels substantially horizontally, and the forming board 6a, the foil box 14, the table roll 16, the wet box 1
By disposing table equipment such as 5, it is also possible to form a paper layer by dehydrating the raw material liquid ejected from the secondary head box 5a.

The operation of the above embodiment will be described. When the papermaking apparatus is activated and the raw material is ejected from both head boxes 5 and 5a, a paper layer is formed on the top wire 2 and travels on the top wire whose direction has been changed downward by the suction coach roll 12a. The direction is changed in the same direction as the bottom wire 1, and the raw material liquid on the bottom wire 1 is mixed on the first forming shoe 7.

[0013] In the first forming shoe 7 part, the density of the mixing part decreases due to the permeation of white water by the dewatering pressure.
Therefore, when a strong pulse pressure is applied when passing through the second forming shoe 8, both dispersions inside the paper layer are promoted, and the formation is improved. At this time, since there is a fiber mixture between the layers, a sufficient interlayer strength can be obtained. If necessary, the concentration of the top layer can be increased by applying a vacuum to the second forming shoe 8.

On the other hand, the raw material liquid jetted from the primary head box 5 onto the bottom wire 1 is subjected to initial dehydration by the forming board 6 to form an initial mat. Thereafter, the first forming shoe 7 engages with the paper layer formed on the top wire, but since the pressing force of the top wire is small, the gap formed on the first forming shoe 7 has a dehydration resistance toward the top wire. , The fibers are smoothly swallowed and the fibers are mainly dehydrated downward while the fiber dispersion is promoted by the pulse pressure of the first forming shoe 7.

If necessary, dehydration can be promoted by applying a vacuum to the first forming shoe 7. As described above, the density of the paper layer is further increased in the low vacuum suction box 9 while being mixed, and the paper layer is transferred onto the bottom wire 1 by the transfer box 10 and then transferred to the next press part by the suction pickup roll 23. Next, the case of performing single-layer making will be described. When making a single layer, the paper layer is formed using only the primary head box 5 without flowing the raw material from the secondary head box 5a. In this case, Japanese Patent Application No. 02-4
Since the operation is a hybrid type operation described in No. 03649, the details will not be described.

Next, the case where three layers are formed will be described. In the case of performing three-layer papermaking, the primary head box 5 can be operated without any problem by using a conventional two-layer paperhead box. To make the best use of these combinations, the inventors' research has shown that 40 gr / m ² , about 1000
380 gr / m thick paper from printing paper equivalent to m / min
It has been confirmed that a multi-layered paper assuming a paperboard having an m ² of about 60 m / min can be produced.

[0017]

The effects of the present invention are as follows. (1) Single-layer making and multi-layer making are possible with one former. (2) The formation of the top layer is improved by the pulse pressure of the second forming shoe 8, and the formation is improved as compared with the related art. Furthermore, the concentration of the top layer is lower due to infiltration of white water in the lamination part, and the lower concentration of the bottom layer is closer to wet-on-wet lamination because of the low concentration of the lamination surface. The internal strength (interlayer bonding strength) is increased in combination with the fiber mixing between the layers.

(3) Since the raw material liquid on the first forming shoe is gently swallowed and has a high dewatering ability to the bottom wire side, the initial dewatering may be small and the overall length is short. (4) When the primary head box is made into two layers to make three layers, the purity between layers can be improved. (5) Since a wide range of basis weights is used, a wide range of paper types and paperboards can be formed with a single former according to the final paper characteristics, and the flexibility is high. Therefore, the present invention can provide a paper layer forming apparatus in which the formation of the paper layer is good, the internal strength is large, and the purity is easily maintained.

[Brief description of the drawings]

FIG. 1 is a front view of a paper layer forming apparatus according to an embodiment of the present invention.

FIG. 2 is a front view of a conventional multi-layer paper forming apparatus using a long net and a short net.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bottom wire, 2 ... Top wire (or medium net, generically a top wire unit), 3 ... Prestrol, 3a
... Prestoring roll, 4 ... Forming roll, 5 ... Primary head box, 5a ... Secondary head box, 6 ... Forming board, 6a ... Forming board, 7 ... First forming shoe, 8 ... Second forming shoe, 9 ... Low vacuum suction Box, 10 ... Transfer box, 11 ... High vacuum suction box,
12. Suction coach roll, 12a, 12b, 12
c: suction coach roll, 13: lead-out roll, 14: foil box, 15: wet box, 16: table roll, 16a: table roll,
17 ... long net, 18 ... short net, 19 ... prestrol, 19
a ... Prestrol, 20 ... Table equipment, 20a ... Table equipment, 21 ... Suction box, 22 ... Turning roll, 23 ... Suction pickup roll, 2
3a: suction pickup roll, 24: primary head box, 24a: secondary head box.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) D21F 1/00-13/12

Claims (1)

(57) [Claims] 1. A dewatered paper layer dehydrated by a table device installed on a second wire loop is combined with the paper layer dehydrated in the first wire loop by the first wire loop. In the paper layer forming apparatus configured to perform the above, on the downstream side of the laminating part of the first wire loop, by applying a pulse pressure to the paper layer running through the first wire loop A paper layer forming apparatus , wherein a forming means for improving the formation of the paper layer and a suction means for increasing the concentration of the paper layer by vacuum suction are connected in the flow direction of the paper layer.