JPH04370291A - Twin wire former in papermaking machine - Google Patents

Abstract

PURPOSE:To provide the title former designed to produce high-quality paper favorable in fiber dispersion with high mechanical strength in its thickness direction by preventing wires' deformation toward inclined surface side through negative pressure to effect protecting mat's fracture. CONSTITUTION:In the title former equipped with a pair of wires 3, 4 traveling while putting a stock liquor 1 in between them, one of the wires 4 is equipped with a shoe blade 13 (1) having a supporting member 17 for preventing said wire 4's deformation through coming into contact with and supporting it and also (2) provided with a inclined surface 13a extending in the wires 3, 4' traveling direction.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twin-wire former paper machine that dewaters raw materials by sandwiching them between pairs of wires.

0002

2. Description of the Related Art FIG. 7 is a block diagram of a conventional paper machine twin wire former. In FIG. 7, the raw material 1 spouted upward from the head box 5 is guided by a breast roll 7 and a homing roll 6, and is sandwiched between two wires 3 and 4 running in a curved manner. 4
The shoe blades 2 run at the same speed as the wires 3 and 4 over a plurality of shoe blades 2 arranged on a certain curvature R' so as to form a convex surface.

The raw material liquid 1 is affected by the energy of colliding with the wires 3 and 4, the squeezing effect due to the wire tension generated by being sandwiched between the converging wires 3 and 4, and the shoe blade 2.
Due to pressure pulses generated during scraping and dewatering pressure such as centrifugal force, substantially equal amounts of water are removed simultaneously on both sides. Further, vacuum dehydration is performed using a suction box 10, a suction couch roll 11, etc., and the material is separated from the wire 4 by a pick-up roll 12 and transferred to a press part for the next process. In addition, in the figure, 8 is a water deflector, and 9 is a vacuum deflector. FIG. 8 shows details of the shoe blade, the tip of which forms a convex surface with a curvature R', which is connected to a plurality of wires 4 as shown in FIG.
is located in the direction of travel.

0004

[Problems to be Solved by the Invention] The shoe blade 2 shown in FIG. 8 generates pressure pulses during dewatering, has the effect of dispersing fibers during dewatering, and improves the texture of the formed paper. It is widely used in the wet paper forming section of However, in the shoe blade 2 shown in FIG. 8, the combination of the various dewatering pressures described above dehydrates both sides at the same time in an almost equal amount, so a cross section with few interfiber bonds is formed in the center of the paper thickness, and up to that cross section, There was a drawback that the consolidation effect (pressing effect) in the next step of pressing (pressing and dehydrating the mat) was difficult to achieve, resulting in the formation of paper with low bonding strength in the paper thickness direction. The present invention aims to solve the problems of the shoe blade in the conventional twin wire former.

[0005]

[Means for Solving the Problems] Therefore, the present invention provides a twin wire former for a paper machine equipped with a pair of wires that run with a raw material liquid sandwiched between them. The shoe blade is provided with a support member that prevents deformation of the wire, and a shoe blade that has an inclined surface that expands in the wire running direction.This is a means for solving the problem.

[0006]

[Operation] The present invention comprises a pair of wires that run with the raw material sandwiched between them, and has a support member on one wire side that contacts and supports the wire to prevent deformation of the wire, and in the wire running direction. It has a shoe blade with an expanding slope. Therefore, on this inclined surface, negative pressure is generated due to the enlargement of the flow path depending on the angle of the inclined surface, and a positive and negative dewatering pressure waveform shown in FIG. 1 is obtained in the running direction of the wire. In other words, by replacing shoe blades with different slope angles, any positive or negative dewatering pressure waveform can be obtained.
Furthermore, by increasing the slope angle toward the downstream side, the amount of water removed to the shoe blade side can be increased, increasing the overall dewatering capacity and making it possible to arbitrarily adjust the dewatering ratio. The directional bond strength can be improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIGS. 1 to 6 show embodiments of the present invention. Now, the twin wire former shown in FIG. 1 has a support member 17 on the downstream side of the shoe blade 2 used in the conventional twin wire former shown in FIG. A major feature is that the shoe blade 13 has an inclined surface 13a (inclined surface angle: θ) that expands in the running direction of the wire 4.

[0008] The following will explain along the flow of the raw material liquid 1.
The raw material liquid 1 sandwiched between the pair of wires 3 and 4 is
, squeeze effect due to tension of 4, white water 1 of shoe blade 2
Due to dewatering pressure such as collision pressure and centrifugal force generated during the scraping step 4, the white water 14 flows simultaneously to both surfaces in approximately equal amounts. Next, the inclined surface 1 that expands in the running direction of the wire 4
As the white water 14 flows out along the line 3a, a negative pressure area is formed on the inclined surface 13a, and dehydration is performed only on the wire 4 side. The dehydrated white water 14 is used for the next shoe blade 2.
It collides with the tip of the pipe, is scraped off, and is discharged from the system.

FIGS. 2 and 3 are explanatory diagrams of a shoe blade 13 having an inclined surface 13a used in an embodiment of the present invention. Here, as shown in FIG. 2, if the shoe blade 13 has no measure to prevent the wire 4 from deforming
In the case where there is no support member 17 shown in FIG. 3), the wire 4 deforms toward the inclined surface 13a side due to negative pressure, the space area 15 shown by the hatched area decreases, and the dehydration ability decreases and the wire 4 deforms. Depending on the flow path shape of the raw material liquid 1, there is a possibility that the mat 16 formed on the wire 4 will be destroyed. Next, as shown in FIG. 3, the embodiment of the present invention has a wire support member 17 that prevents deformation of the wire 4, so that a space area 15 is secured and sufficient dewatering capacity is provided, and furthermore, a flow path is provided. Since there is little deformation of the shape, there is no fear that the mat 16 formed on the wire 4 will be destroyed.

4 to 6 show examples in which support members 17 for supporting the wire 4 are attached to the inclined surface 13a in order to prevent the wire 4 from being deformed. FIG. 5 is a case in which a plurality of support members 17 are integrally connected, and FIG. This is the case.

[0011]

[Effects of the Invention] As explained in detail above, the present invention has a support member on one wire side that contacts and supports the wire to prevent deformation of the wire, and an inclined surface that expands in the wire running direction. Since the shoe blade is provided, the wire will not be deformed toward the inclined surface due to negative pressure, and the space on the inclined surface is secured to provide sufficient dewatering capacity. Therefore, the present invention uses pulsed dewatering pressure in twin wire formers of paper machines to increase dewatering capacity and arbitrarily adjust the dewatering ratio while preventing fibers from coagulating together (flocking), thereby increasing the strength in the paper thickness direction. , high-quality paper with good fiber dispersion can be produced under a wide range of papermaking conditions.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration and dewatering pressure profile of a dewatering device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the drawback of using only the shoe blade shown in the embodiment of the present invention.

FIG. 3 is an explanatory diagram of the flow when using a shoe blade and a support member showing a second embodiment of the present invention.

FIG. 4 is a perspective view of a shoe blade using a support member showing a first embodiment of the present invention.

FIG. 5 is a perspective view of a shoe blade using a support member showing a second embodiment of the present invention.

FIG. 6 is a perspective view of a shoe blade using a support member showing a third embodiment of the present invention.

FIG. 7 is a side sectional view showing a conventional twin wire former.

FIG. 8 is an explanatory diagram showing the state of liquid flow when a conventional shoe blade is used.

[Explanation of symbols]

1 Raw material liquid 2 Shoe blade 3,4 Wire 13 Shoe blade 13a　Slope surface 14 Hakusui 15 Spatial area 16 Mat 17 Wire support member

Claims (1)

[Claims] [Claim 1] A twin wire former for a paper machine equipped with a pair of wires that run while sandwiching a raw material liquid, the twin wire former having a support member on one wire side that contacts and supports the wire and prevents the wire from deforming. A twin wire former for a paper machine, characterized in that a shoe blade is provided with an inclined surface that expands in the wire running direction.