JPS6120650B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a web forming method and apparatus for forming a web of uniform thickness.

[Conventional technology]

Techniques are known for forming a web on a carrier by conveying particulate material into a dispensing chamber with carrier air. The air flow is caused to vibrate across the width of the distribution chamber by impulses from a control jet, thereby forming a web on the surface of the carrier.

[Problem that the invention seeks to solve]

Although the above web forming means has no problems in terms of web uniformity and quality and can increase production output, the composite flow of materials fed to the distribution chamber does not require high speeds that form veins. A problem arises when the webs are introduced, resulting in irregularities in the thickness and quality of the web formed.

Furthermore, the static electricity generated in wood particles, especially those with a moisture content of less than 10%, tends to cause abnormalities during the web formation, as the charged particles are deposited on the walls of the chamber and fall down in clumps. It was hot. Further, if the static electricity is particularly strong, sparks may be generated, which is a problem.

[Means for solving problems]

The present invention has been made in view of the above points, and
A method and apparatus for forming a web that does not form veins even when a composite flow containing materials supplied into a distribution chamber provided with a conveyor is a high-speed flow and ensures the quality and uniformity of the web. The purpose is to provide.

[Effect]

The method of forming a web according to the present invention is to create a zigzag flow by passing a composite flow containing particulate material into a gaseous carrier through a zigzag-shaped passage, and to create a composite flow by passing a passage with a large cross-sectional area in the flow direction. The granular material in the flow is uniformly dispersed, and then the composite stream is guided into a distribution chamber, a layer of granular material is deposited on a conveyor provided in the distribution chamber, and the granular material layer is injected from both sides of the composite stream toward the composite stream. It is characterized in that the gaseous medium flow gives the composite flow an oscillating flow in the width direction of the distribution chamber, thereby making the web forming layer uniform in the width direction.

A method of forming a web according to the present invention includes a distribution chamber;
A conveyor provided in the distribution chamber, a nozzle that opens into the distribution chamber and supplies a composite flow in which particulate material is dispersed in carrier gas, and a nozzle provided on both sides of the composite flow to supply the composite flow to the entire width of the distribution chamber. a blow box for supplying a controlled air flow to the composite flow to provide a variable impulse; and a zigzag passage provided upstream of the nozzle, the zigzag passage in the flow direction of the composite flow. It is characterized by being set so that the cross-sectional area increases.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 5, the web forming apparatus according to the present invention is equipped with a distribution chamber 1 whose lower part is open to accommodate a conveyor belt 5 constituting the web forming surface. Above the distribution chamber 1 there is an inlet nozzle 3 connected to the supply pipe 2 through a transition region 90 with a zigzag-shaped passage 91;
Also, there are blow boxes 1 on both sides of this inlet nozzle 3.
1 and 12 are provided. The composite stream of gaseous carrier mixed with particulate material from passage 91 is transferred to the sixth
As shown in the figure, the air is supplied into the distribution chamber 1 through the inlet nozzle 3, and is vibrated in the width direction of the distribution chamber 1 by the impulse jet flow exiting from the blowboxes 11 and 12.

According to the invention, the transition region 90 allows the particulate material to be well dispersed in the carrier air stream. For this purpose, the cross-sectional area of the transition region 90 is set such that it is enlarged in the direction of fiber flow and in the longitudinal direction of the web being formed. As is apparent from FIGS. 2 and 5, the transition region 90 also forms a zigzag-shaped passage, which redirects the carrier air stream with the particles therein several times during their passage through the transition region 90. You will be forced to do so. Each time the combined flow is diverted, a resistance is created which is balanced by the pressure change resulting from the reduction in air velocity due to the enlargement of the cross-sectional area of the zig-zag passage. This reduction in air velocity prevents the development of local excessive velocities that would form veins in conjunction with the deflection walls of the passage.
The combined gas/particle stream will thus enter the distribution chamber 1 with a uniform velocity cross-sectional distribution when leaving the nozzle 3. The velocity of the composite flow varies, for example, from 25 m/sec to 10 m/sec while the composite flow passes through the transition region.
m/sec. Advantageously, the flow velocity of the combined stream is reduced to at least 1/2 of the original velocity.

Another feature of the invention is that the passageway 91 in the transition region
is lined with a wood material 92, preferably plywood, wood fiber planks, etc., which effectively reduces the generation of static electricity in the particulate material or fibers. For example, experiments have shown that the electric field strength can be reduced from about 200KV/m to 30KV/m by using this device. The invention is not limited to the particular shape of the transition region described above, but other shapes may be used. It may also be provided in the supply pipe 2 apart from the distribution chamber.

3 and 4 show different embodiments of the blowboxes 11 and 12 in detail.
As shown in FIG. 3, an ionizing rod 93 is provided in the dispensing chamber near the blowbox to further reduce static electricity. This ionized rod 9
3 is connected to an AC power source (not shown) capable of ionizing the surrounding gas, thereby further reducing static electricity remaining on the fibers in the composite stream introduced from the nozzle 3. The voltage applied from the AC power source is preferably in the range of 3 to 20 KV.

FIG. 4 shows an embodiment in which ionizing rods 94 are placed within blowboxes 11 and 12 to ionize the flow creating impulse jets that control the oscillations of the composite flow flowing through distribution chamber 1. Such an arrangement effectively ionizes and mixes the impulse jet into the composite stream.
The ionizing rod located within the blowbox is protected from mechanical damage and also from dust deposits. Additionally, the ionizing rod within the blowbox is shielded to prevent maintenance personnel from directly touching the ionizing rod.

Although particular embodiments of the invention have been illustrated and described herein, it is clear that the invention is not limited to these embodiments and that various modifications and combinations may be practiced within the scope of the invention. It can be taught.

〔Effect of the invention〕

As described above, according to the present invention, even if the composite flow is a high-speed flow, veins are not formed, and the quality and uniformity of the web can be ensured at a higher level than in the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a transition region portion of the web forming method according to the present invention, FIG. 2 is a cross-sectional view of the transition region,
FIG. 3 is a diagram showing a modification in which the ionization rod is placed inside the distribution chamber, FIG. 4 is a diagram showing a modification in which the ionization rod is installed in the blow box, and FIG. 5 is a perspective view of the web forming method according to the present invention. , FIG. 6 is a lateral sectional view through the distribution chamber of the same web forming apparatus. 1... Distribution chamber, 2... Supply pipe, 3... Nozzle,
5... Conveyor belt, 11, 12... Blowbox, 90... Transition area, 91... Passage, 92...
Wood material, 93...Ionized rod.

Claims (1)

[Claims] 1. A composite flow in which particulate material is mixed into a gaseous carrier,
The zigzag flow is created by passing through a zigzag-shaped passage, and the particulate material in the composite flow is uniformly dispersed by passing through a passage with a large cross-sectional area in the flow direction, and then the composite flow is guided to the distribution chamber. A granular material layer is deposited on a conveyor provided in A method for forming a web, characterized by forming a web uniformly in the width direction. 2. A distribution chamber, a conveyance chamber provided in the distribution chamber, a nozzle that opens into the distribution chamber and supplies a composite flow in which particulate material is dispersed in a carrier gas, and a nozzle provided on both sides of the composite flow to supply a composite flow in which particulate material is dispersed in a carrier gas. a blow box for supplying a controlled air flow to the composite flow to provide a variable impulse across the entire width of the distribution chamber; and a zigzag passage provided upstream of the nozzle, the zigzag passage being A web forming device characterized in that the cross-sectional area is set to expand in the flow direction of a composite flow.