JPH02269890A - Twin wire former of paper-making machine - Google Patents

Abstract

PURPOSE:To improve the interlaminar strength of paper without breaking the formation of the paper by disposing a dehydration-controlling shoe and a dehydrating device in the first wire loop. CONSTITUTION:A dehydration-controlling shoe 6 is disposed at a position adjacent to a pressed roll 4 in the loop of the first wire 1 to press back white water fed from a raw material solution on the side of the wire 1 toward the raw material solution with the action of the formed wedge-like space. A non- porous roll 7 for dehydration is disposed at a position following to the dehydration-controlling shoe 6 on the down stream side of the running direction of the wire and further a non-porous roll 9 for the dehydration is disposed on the down stream side of a vacuum roll 8. The dehydration ratio of the paper material can be heighten on the one side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a twin wire former for a paper machine that forms a wet paper web between two wires.

[Conventional technology]

In a twin wire former, two wires each form a loop, and while the raw material liquid is sandwiched between them and runs, water is removed from the raw material liquid by various dehydrating devices, and a fiber mat gradually grows. The twin-wire former, in which paper webs are formed, is unique in that it enables higher speeds by eliminating the free surface of the raw material liquid that was present in previous paper machines.

A twin wire former having a shoe type dewatering device, which is one type of conventional twin wire former, will be explained based on FIG. 6.

The raw material liquid 20 spouted upward from the head box 3 is
It is sandwiched between two wires, top wire 2 and bottom wire 1, guided by forming roll 5 and breast roll 4, and is placed on a certain curvature R while narrowing the gap at the same speed as wire 1゜2. The bottom wire runs along an approximate curve R on a plurality of shoe blades 21 provided at intervals.

The raw material liquid 20 is affected by collision energy when it collides with the wire 1 or 2, a squeezing effect due to wire tension when it is sandwiched between the converging wires 1 and 2, pressure pulses and centrifugal force generated by the scraping action of the shoe blade 21, etc. The same amount of water is removed from both sides at the same time by the dewatering pressure, and a fiber mat gradually grows and a paper web is gradually formed.

Next, dewatering is performed by vacuum in the Sakshitankkusu 23 and the Sakshitank-Tyrol 12 to form a water line. The paper web is transferred onto the bottom wire 1 on the suction couch roll 12, picked up by the suction pickup roll 13, and transferred to the next press part.

The water deflector 22 and the vacuum deflector 24 are devices that are in contact with the top wire 2 and remove water discharged from the top wire 2.

[Problem to be solved by the invention]

The twin wire loop of the conventional shaver tube described above performs the initial wet paper web formation using pulsed pressure generated by shoe blades disposed intermittently at intervals.

In this method, the movement of the fibers is large and the paper's texture is improved, but the yield is low because equal amounts of water are dehydrated on both sides at the same time, and the fibers are bonded in the center of the paper thickness where the mantle is formed. This method has the drawback that a portion (void) with a small amount of water is formed, and the strength in the paper thickness direction (hereinafter referred to as interlaminar strength) is lower than that of one in which water is dehydrated only on one side.

In order to solve these problems, currently a fourdrinier is installed before the raw material is sandwiched between two wires, and about 60 to 70% (depending on the papermaking conditions) of the water ejected from the head box is dehydrated downward. After that, a so-called high-print type loop, which dewaters on both sides at the twin wire section, was developed and is gaining popularity.

When we examine the cross-sectional structure of paper made with this hybrid type loop, we find that there are areas with few interfiber points (voids).
is smaller than that of the twin wire loop, and the part with the largest void is not in the center of the paper thickness but in a part near the paper surface. Therefore, the bonding strength of the fibers in the paper thickness direction is high, and the effect of increasing the density of the paper due to the press following the loop is greater as it is closer to the paper surface, so having the voids closer to the surface has the advantage that the pressing effect is greater.

As a result, the glabella strength of the hybrid type loop is greater than that of the twin wire loop.

However, since this hybrid type loop has a long section to solve the problem, it suffers from the same drawbacks as the long section and paper machine, namely: (1) Excessive dispersion of the raw material liquid at high speeds occurs.

(2) Poor position.

(3) Poor width profile.

In order to achieve higher speeds and higher quality in the future, it is necessary to create a true twin wire loop in which the raw material jet ejected from the head box is immediately sandwiched between two wires.
It is believed that.

The present invention aims to provide a twin wire loop that can provide glabella strength equivalent to that of a Fourdrinier paper machine, which has high glabella strength, without disturbing the fabric.

[Means to solve the problem]

In the present invention, the raw material liquid ejected from the head box is
and a twin wire loop of a paper machine that performs wet paper web formation between sandwiched wires forming two second loops, provided within the loop of the first wire,
A stationary shoe that supports the first wire and suppresses dewatering to the first wire side, and a roll-shaped dewatering device that is installed in the loop of the first wire following the shoe and dewaters to the second wire side. Equipped with equipment.

[Effect]

Regarding dewatering of twin wire loops, during the wet paper forming process up to the formation of a water cut line (called a dry line in the paper industry), the dewatering ratio to one side (the ratio of the amount of water dewatered to the jet flow rate of the head box) ) exceeds 70%, as shown in Figure 5, the glabellar strength also improves almost in proportion to the increase in dehydration rate, and when it exceeds about 90%,
The same level of glabellar strength as paper that has been completely dehydrated on one side, such as on a Fourdrinier paper machine, can be obtained.

In the present invention, within the loop of the first wire, the first
A stationary shoe that supports the first wire and suppresses dewatering to the first wire is followed by a roll-shaped dewatering device that dewaters the second wire in the same loop. One side of the second wire is dehydrated using the shoe and roll-shaped dehydrator. As a result, dehydration can be performed on one side (asymmetrically) to a dehydration rate that improves the strength of the glabella.

〔Example〕

A first embodiment of the present invention will be described with reference to FIG.

This embodiment includes a first wire 1 and a second wire 2 forming respective loops, and a head is placed between a breast roll 4 that guides the first wire 1 and a homing roll 5 that guides the second wire 2. A raw material liquid is ejected from the box 3 and is sandwiched between both wires 1.2. The dehydration suppressing shoe 6 is provided close to the breast roll 4 within the loop of the first wire 1 .

As shown in the drawing, the dehydration suppressing shoe 6 has a plurality of inclined parts 6A forming a wedge-shaped space whose wire entry surface expands in the width direction and upstream in the wire running direction with respect to the surface of the first wire l. It has a serrated shape with a sawtooth shape, and the white water that once came out from the raw material liquid to the first wire side is pushed back to the raw material liquid side by the action of this wedge-shaped space, suppressing dehydration to the first wire side. It is now possible to do so. Note that the dehydration suppressing shoe 6 may be constructed by arranging a plurality of single shoes having the above-mentioned inclined portions so as to be freely inserted and removed.

Following the dehydration suppressing shoe 6, a non-perforated roll 7 for dewatering is installed in the loop of the first wire 1 on the downstream side in the running direction of the wire, and a vacuum roll 8 is installed in the loop of the second wire 2 further downstream. , a non-porous dewatering roll 9 in the loop of the first wire 1, and further downstream a transfer box 10 for ensuring the transfer of the wet paper to the second wire 2 by vacuum suction.
and a second vacuum roll 12 are provided.

On the other hand, a return roll 11 for the first wire 1 is provided at an intermediate position between the transfer box 10 and the second vacuum roll 12, and a suction vacuum amplifier for sucking wet paper is provided on the downstream side of the second vacuum roll 12. A roll 13 is provided. 14 is a saveall that collects the white water discharged to the first wire 1 side by the vacuum roll 8, and 15 is a saveall that collects the white water discharged from the dehydration suppressing shoe 6 and the dewatering roll 7.

In this embodiment, the raw material liquid spouted from the head box 3 is immediately sandwiched between two wires, the first wire l and the second wire 2, and the dehydration suppressing shoe 6 moves the raw material liquid in the direction of the second wire 2 (in the downward direction in the figure). ) dehydration is performed. The dehydrated white water is collected in the saveall 15 and discharged outside the system.

Furthermore, a dewatering roll 7 of a hole is arranged on the downstream side, and a vacuum rotating to the zeroth order dewaters the water to the second wire 2 side so that most of the water in the raw material is dehydrated to the second wire 2 side. Most of the water is removed toward the second wire 2 by the roll 8 (part of the water is removed toward the first wire due to centrifugal force, etc.), and a water break line is formed.

After this, dehydration is further performed on the second wire 2 side by the dehydration roll 9 and the transfer sacsilane box IO,
The matte density is increased to 18 to 20% to form a paper web, which is sucked by the pickup roll 13, separated from the second wire 2, and conveyed to the next press part.

In addition, from the viewpoint of improving the profile in the middle direction, at the landing part of the paper stock material to the first wire 1 and the second wire 2,
It is desirable that a portion of the water be dehydrated to the first wire side using the breast roll 4.

As explained above, in this embodiment, in the initial dewatering section, dehydration is performed on one side toward the second wire side using the dehydration suppressing shoe 6, the non-porous dewatering roll 7, etc. The dehydration rate can be increased, thereby improving the interlaminar strength.

A second embodiment of the present invention will be explained with reference to FIG.

In this embodiment, a stationary dehydration shoe 16 is provided in the loop of the second wire 2 between the non-porous dehydration roll 7 and the vacuum roll 8 of the first embodiment, and a part of the dehydration shoe 16 is provided toward the first wire 1 side. It is designed to dehydrate, and in addition to the functions and effects of the first embodiment, it has the effect of equalizing the history of the formed paper,
It is possible to improve the quality difference between the front and back sides of the paper web.

A third embodiment of the present invention will be described with reference to FIG.

In this embodiment, a dehydration suppressing shoe 16' similar to the dehydrating suppressing shoe 6 is installed in place of the dehydrating shoe 16 of the second embodiment, and the amount of dewatering to the first wire 1 side is increased to increase the amount of water removed from the paper. The difference in quality between the front and back of the fish can be made extremely small.

A fourth embodiment of the present invention will be described with reference to FIG.

In this embodiment, in the first embodiment, the second wire 2
In order to increase the amount of dewatering to the side, a vacuum suction box 17 is provided in the loop of the second wire between the dehydration suppressing shoe 6 and the non-porous dewatering roll 7.

In this embodiment, the vacuum suction box 17 further
The dehydration rate toward the wire 2 side is increased, and the glabella strength is further improved.

In the above embodiment, the dehydration suppressing shoe has a sawtooth shape (has a rust space), but as described in Japanese Patent Application No. 63-285871 filed earlier by the present applicant, it has a smooth shape with a curvature. A single wedge-shaped space may be formed on the entry side of the first wire by a shoe, or a plurality of wedge-shaped spaces may be formed by a plurality of arcuate protrusions.

〔Effect of the invention〕

The present invention provides a paper machine twin wire loop having first and second wires, and a stationary shoe that suppresses dewatering in the initial dewatering section and a roll-shaped dewatering device A that dewaters to the second wire side. The following effects can be obtained by arranging the wire in the loop of wire No. 1.

(1) Since the one-side dewatering ratio can be increased, it is possible to obtain the same level of interlaminar strength as a long paper machine even though it is a twin wire loop.

(2) High-speed operation is possible because the raw material liquid ejected from the hend box is sandwiched between two wires before being disturbed.

[Brief explanation of drawings]

FIG. 1 is an overall view of the first embodiment of the present invention, FIG. 2 is an overall view of the second embodiment of the invention, FIG. 3 is an overall view of the third embodiment of the invention, and FIG. The figure is an overall view of the fourth embodiment of the present invention, FIG. 5 is a graph showing the relationship between dehydration ratio and glabellar strength in a twin wire loop, and FIG. 6 is an overall view showing a conventional twin wire loop. l...first wire, 2...second wire, 3
...Head box, 4...Prestrol, 5
... Forming roll, 6... Dehydration suppressing shoe,
7... Non-porous dehydration roll, 8... Vacuum roll, 9...
...Dewatering roll, 10...Transfer box, 11...Return roll, 12...Second vacuum o -
13... Bin up roll, 16... Fixing shoe, 16' Dehydration suppressing shoe, 17 Vacuum suction box. Agent: Patent Attorney Akigai Sakama (2 persons) Figure 5 Dehydration Ratio Figure 6

Claims (1)

[Claims] The paper stock material ejected from the head box is transferred to the first and second
In a twin wire former of a paper machine, which is sandwiched between two dewatering wires forming two loops and dewatered between the two wires to form a wet paper, a wire is provided within the loop of the first wire,
A stationary shoe that supports the first wire and suppresses dewatering to the first wire side, and a roll-shaped shoe that is installed in the loop of the first wire following the shoe and dewaters to the second wire side. A twin wire former of a paper machine characterized by being equipped with a dewatering device.