JP2642980B2 - Web forming and dewatering section of paper machine - Google Patents

Description

The present invention relates to an improved web forming and dewatering section applied to a paper machine.

[Conventional technology]

FIG. 3 shows a general example of a twin wire device having an upper wire unit.

The paper raw material 2 spouted from the head box 1 lands on a loop-shaped lower wire (four net) 3 and is dehydrated by an initial dehydrator 4 below the lower wire 3, and then forms a loop with the lower wire 3. The dehydrating device 5 and the lower dehydrating device 6 sandwiched between the upper wires 9
The upper wire 9 is separated from the web 2b,
Is further dehydrated by a moisture adjusting device 7 and transferred to a press part by a suction pickup roll 8.

Upper dehydrator 5 and lower dehydrator 6 shown in FIG.
An example of the prior art is shown in FIG.

The paper raw material 2 shown in FIG. 3 is dehydrated downward in the initial dewatering section 4, and is sandwiched between the upper wire 9 and the lower wire 3 at the entry side of the lower shoe box 10 shown in FIG. The lead-in shoe 17 and the plurality of shoes 21 of the side shoe box 10
Gives a repeated dehydration pressure, improves the formation while being dehydrated, and forms a paper layer.

The water dehydrated on the upper side of the lower shoe box 10 is received by the auto slice 18. The upper wire 9, the stock and the lower wire 3 are wound by the roll 12 behind the auto slice 18 at a curvature opposite to the curvature of the shoe box 10, and the stock receives the surface pressure and centrifugal force of the lower wire. It is dehydrated on the lower side,
In addition, upward water sucked at the separated portion between the roll 12 and the upper wire 9 is received by the saveall 23.

The web having the paper net formed by dewatering between the long net portion and the upper and lower wires is transferred to the lower wire side by the vacuum box 14 at the portion where the upper and lower wires are separated.

The twin-wire device shown in FIG. 5 differs from the twin-wire device shown in FIG. 4 by adding a vacuum box 24 under the lower wire 3 between the auto slice 18 and the roll 12. This is to enhance the dewatering of the twin-wire device shown.

What is shown in FIG. 6 is the roll 12 shown in FIG.
This is an example in which a dehydration shoe 31 is installed on the upper wire side instead.

[Problems to be solved by the invention]

FIG. 7 shows the relationship between the upward dewatering ratio of the twin-wire apparatus of the type shown in FIG. 4 and the paper quality.

For paper quality such as formation, air permeability, paper quality, front / back difference, paper strength, etc., there is an appropriate upward dewatering ratio according to each requirement. In the actual operation, when various paper types are produced, it is desirable to adjust the upward dewatering ratio for each paper type according to the importance of the paper quality.

Adjustment of the upward dewatering ratio of the conventional twin-wire apparatus shown in FIG. 4 is mainly performed when the flow rate of the raw material from the head box 1 and the paper making speed are constant. Can be carried out by changing the degree of vacuum.

That is, the upward dewatering amount is determined by the upper wire 9 and the lower wire 3
When the degree of vacuum of the low vacuum box 22 arranged before contacting with the lower vacuum box 22 is maximized, the amount dehydrated upward in the lower shoe box 10 is set as the lower limit, and when the vacuum of the low vacuum box 22 is turned off, the lower shoe box 10 The adjustment is performed in this range, with the amount dehydrated upward at the upper limit.

Water that has not been completely dehydrated by the shoes 17 and 21 of the lower shoe box 10 is carried to the roll 12. Under high-speed, high-volume operating conditions, a large amount of water is dewatered by these 12 rolls. However, the pressure applied to the stock at the roll 12 has a lower paper layer improving ability than the repetitive pressure at the shoe.

In order to reduce the dehydration in the roll 12 part, as shown in FIG. 5, a vacuum box 24 having a slot on the lower wire side between the auto slice 18 and the roll 12 was considered. The repetitive raw material pressure acting at this time is
Since it is provided through the fiber mat on the lower wire side (the fourdrinier side) which has already been sufficiently formed, it is not efficient, and the dehydration reinforcement in this portion acts to lower the upper dewatering ratio.

In addition, in the conventional example shown in FIG. 6, a shoe 31 is disposed instead of the roll 12 shown in FIG. 4, and the dehydration pressure form of the roll is replaced with a repeated dehydration pressure form by the shoe from the upper wire side. Things. The upper and lower wires once wound downward by the shoe 21 of the lower shoe box are again wound upward by the shoe 31 to form a paper transfer vacuum box.
At the position 14, it is returned to almost the same height as the upper surface of the initial dewatering device 4.

In this device, when the number of shoes 31 is small,
Since the radius of curvature of the portion becomes small and the surface pressure of the shoe portion due to the wire tension increases, the wear of the upper wire is accelerated.

An object of the present invention is to solve the above-mentioned drawbacks of the web forming and dewatering section of the conventional twin wire device.

[Means for solving the problem]

The present invention provides a dewatering method in which an upper wire, a stock material, and a lower wire are wound around and run from a stock material sandwiched by the upper wire and the lower wire. In a web forming and dewatering section of a paper machine including a plurality of shoes arranged on the wire side and an auto slice receiving the upper dewatering by the shoes, the web is disposed on the upper wire side following the auto slicing behind the shoes. A vacuum box having a slot on the contact surface with the upper wire, and a top box, a stock and a bottom wire which are arranged at the back of the vacuum box, wound around the curvature of the shoe in a direction opposite to the curvature of the shoe, and arranged at the top wire side. Roll.

(Operation)

The present invention relates to a vacuum having a slot between a plurality of shoes on a lower wire side for dehydrating by winding and running a material wire sandwiched between the upper and lower forming wires and an upper wire side roll behind the shoes. By disposing the box on the upper wire side, dewatering pressure is more effectively applied to the raw material from the upper wire side where the wet paper density is lower and the fibers are easy to move in the paper thickness direction, and upward effective dewatering is performed. Further, by adjusting the degree of vacuum of the vacuum box, the upward dehydration amount can be adjusted, so that the control of the quality of various papers becomes easy. In addition, by applying a dehydrating pressure to the raw material from the upper wire side, which has a large amount of easily movable fibers, as described above, the formation of paper is improved.

Furthermore, by providing a roll on the upper wire side at the rear of the vacuum box and making its curvature in the opposite direction to the curvature of the plurality of shoes, the need to reduce the radius of curvature of the vacuum box is eliminated,
Wire wear due to wire tension can be minimized.

Further, since the vacuum box can also absorb water in the upper wire, the splash generated when the 2.5-layer wire and the 3-layer wire are used under high-speed operation conditions, etc.
Mist can be reduced.

〔Example〕

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

In the present embodiment, in the web forming and dewatering section of the above-described conventional paper machine of the type shown in FIG. 4, an auto-slice subjected to upper dehydration by the lower shoe box 10 on the lower wire side.
The vacuum box 19 having one slot 11 is provided on the upper wire side following the upper wire side, and the shoe box 10 is provided on the upper wire side behind the vacuum box 19.
A roll 12 having a curvature in a direction opposite to the curvature of the roll 12 was provided.

The slot 11 of the vacuum box 19 is formed by shoes 21 and 13, and the degree of vacuum in the vacuum box 19 can be adjusted by means not shown.

In this embodiment, as described above, the shoe box
The stock dewatered downward by 10 is then evacuated to a vacuum box 19
As a result, the fiber mat is not formed, and the fibers are dehydrated upward from the upper wire side where the fibers are easy to move, so that effective dehydration can be performed. Therefore, by adjusting the degree of vacuum of the vacuum box 19, it is possible to obtain an appropriate upward dewatering amount according to the required paper quality.

Further, as described above, the formation of the paper can be improved by dehydration from the upper wire side where the fiber mat is not formed and the fibers are easily moved.

Further, behind the vacuum box 19, since the roll 12 having a curvature in the opposite direction to the shoe box 10 is provided on the upper wire side, the curvature of the vacuum box 19 can be increased,
Wire abrasion due to wire tension can be reduced.

Furthermore, since the vacuum box 19 also sucks water in the upper wire, splashes and mist from the same wire are reduced.

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

In this embodiment, the vacuum box 19 of the first embodiment has a plurality of (three) slots. As shown in the figure, the vacuum box 19 is provided with three slots 11 by shoes 20, 25, 26, and 13, so that the space between the shoes 20 and 25 can be adjusted according to the speed increase and production increase plan of the paper machine. The slot and the slot between the shoes 25 and 26 are closed with a plate made of high-molecular polyethylene or the like so that the number of effective slots can be adjusted and the amount of vacuum air can be reduced.

A number of mounting bases for the shoes 21 of the lower shoe box 10 are prepared, and the mounting base is a T-type slide type.
The number of the shoes 21 can be changed freely by inserting and removing, so that the magnitude of the material pressure and the number of repetitions can be adjusted repeatedly, and the degree of vacuum of the lower shoe box 10 can be adjusted. Has become. Further, by dividing the box into a plurality of spaces, the degree of vacuum in each space may be changed to adjust the material pressure acting on each shoe portion.

Further, the lead-in shoe 27 of the lower shoe box 10 at the portion between the stock and the upper wire and the lower wire is the first shoe.
Instead of a solid shoe such as the shoe 17 shown in the figure, a slotted shoe as shown in FIG. 2 is attached, and by adjusting the degree of vacuum in the space below the shoe 27 of the shoe box 10, the paper material is clamped. The raw material pressure in the only part can be adjusted.

Also in this embodiment, similarly to the first embodiment, the upward dehydration is effectively performed by the vacuum box 19, and an appropriate upward dehydration amount suitable for the paper quality is obtained, and the wire is worn by the wire tension. Can be reduced.

Further, the amount of dewatering of the stock is adjusted by adjusting the number of slots of the vacuum box 19, inserting and removing the shoes 21 of the lower shoe box 10, and employing the slotted shoes 27 of the lower shoe box 10 as described above. This becomes even easier.

In each embodiment, as shown in FIG. 2, a shower box 28 is provided in the vacuum box 19 to supply fresh water or white water to the space 30 inside the vacuum 19th slot as necessary. The inside of the space 30 and the slot 11 can be kept clean. Further, by providing a fixed or rotating shower 33 over the entire width in the auto slice 18 and the vacuum box 19, solidification of internal dirt can be prevented.

Further, the mist blown to the lower part of the roll 12 is recovered by a mist treatment device 29 which forms a spiral cylinder and opens as shown in FIG. 2, and the atmosphere around the roll 12 can be kept clean.

The use of the shower 28 can prevent the solidified fibers from being mixed into the white water reused by the shower 33 without any loss of the slots 11, and reduce the load of filtering the reused water. In addition, the use of the mist treatment device 29 causes mist in the air current flowing along the traveling wire to contaminate the machine frame, etc., and to reduce the solidification of the fine fibers in the mist attached to the machine frame, etc. Cleaning work and time are reduced.

〔The invention's effect〕

As described above, in the present invention, by arranging the vacuum box having a slot on the upper wire side behind the auto slice, it is possible to raise the upper limit of the upward dewatering amount in the conventional technology and to use various paper types. In papermaking, an upward dewatering amount suitable for paper quality can be easily obtained.

In particular, in high-speed, high-volume papermaking, the concentration of wet paper at the inlet of a vacuum box having the above-mentioned slot is low, and the slot of the vacuum box can move the pulse-like dehydration pressure from the top side of the wet paper, which has a lot of fibers. By dehydrating while giving the paper, and by completing the paper layer formation up to this portion, the formation of the paper can be improved.

Further, in the present invention, since the roll having the curvature in the opposite direction to the lower shoe box is arranged on the upper wire side at the rear of the vacuum box, the radius of curvature of the shoe portion of the vacuum box can be made sufficiently large. In addition, the frictional force between the wire and the shoe can be minimized, and the wear of the wire due to the pressure applied to the shoe by the wire tension can be suppressed.

Further, since the vacuum box can also suck water in the upper wire, splashes and mist generated when the 2.5-layer wire and the 3-layer wire are used under high-speed operation conditions are reduced. be able to.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a web forming and dewatering unit according to a first embodiment of the present invention, FIG. 2 is a configuration diagram of a web forming and dewatering unit according to a second embodiment of the present invention, and FIG. Overall view of the wire part of a conventional paper machine with a unit, Fig. 4, Fig. 5,
FIG. 6 is a block diagram showing an example of the upper and lower dewatering devices of a conventional paper machine having the above upper wire unit, and FIG. 7 is a graph showing the relationship between various paper qualities and the upper dewatering ratio. 3 ... lower wire, 9 ... upper wire, 10 ... lower shoe box, 11 ... slot, 12 ... roll, 13 ... shoes, 14 ... vacuum box, 17 ... lead-in shoe, 18 ... ... Auto slice, 19 ... Vacuum box, 20,21,25,26 ... Shoe, 23 ... Save all, 27 ... Lead in shoe with slot, 28 ... Shower, 29 ... Mist treatment device, 30 ... … Space inside the slot, 33 …… Shower.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akihito Nagano 5007 Itozaki-cho, Mihara-shi, Hiroshima Pref. Mihara Works, Mitsubishi Heavy Industries, Ltd. (56) References JP-A-61-63793 (JP, A) JP-A-61 −119796 (JP, A)

Claims (1)

(57) [Claims] An upper wire, a stock material, and a lower wire are wound on and run from a stock material sandwiched between the upper and lower two loop-shaped continuous forming wires and the upper wire and the lower wire to perform dewatering. In the web forming and dewatering section of a paper machine, comprising a plurality of shoes arranged on the lower wire side and an auto slice receiving the upper dehydration by the shoes, the web is disposed on the upper wire side after the auto slicing behind the shoes. A vacuum box having a slot on the contact surface with the upper wire, and an upper wire, a stock and a lower wire which are arranged behind the vacuum box and wound with a curvature in a direction opposite to the curvature of the shoe and arranged on the upper wire side. A web forming and dewatering section of a paper machine, comprising: