JPS5949358B2 - Web processing method and device in the press section of a paper machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides that the press section has a central roll with a smooth surface defining at least two consecutive nip sections with the rolls, preferably with a recessed surface roll in the press section. defining a first nip of the double felt between itself and a suction roll, which suction roll together with said central roll define a second repression nip of the press section, and for separating the paper web from the central roll; The present invention relates to a method for processing a web in a press section of a paper machine, which utilizes rotating suction transfer rolls for processing the web to guide the web further forward.

The invention further relates to a web processing device in a press section of a paper machine, in which the suction transfer roll which together with the central roll defines the nipping section is a suction transfer roll having cellular structures.

The web processing method and web processing apparatus according to the present invention were originally published in Finnish Patent No. 5 by the applicant of this application.
Although the invention is intended to be applied in conjunction with the press section described in the '0651 specification, it is not intended to limit the invention thereby.

Generally known processing methods according to the prior art in paper machines for separating the web from the surface of a rotating pressure roll and for moving the web in continuous form to the next processing step include:
The basis is that the web speed in the next processing step is higher at the surface of the suppression roll.

As can be seen, separation of the web takes place with the aid of speed differences or tensile forces.

The tensile forces create stresses and tensions in the web that cannot necessarily be withstood by the web, and the web breaks, which means an interruption in continuous production and a loss of production.

Modern paper machines are characterized by high processing speed.

The higher the speed of the paper machine, the less time the web is under pressure in the nip between the rolls.

This reduces the dewatering capacity of the press and therefore requires K to use high pressures when the paper machine speed is high, in order to make the action of the press more effective.

A converse effect of increasing the pressure is that the web adheres too closely to the smooth press roll surface, making separation of the web from the surface more difficult.

This increases the tendency of the web to break and the production losses that occur in the event of a web break correspondingly increase.

The damage that causes the web to break occurs particularly at the edges of the web.

Therefore, the present invention pays particular attention to the treatment of the edges of the web.

In order to overcome the above-mentioned drawbacks, in the processing method of the invention, the suction transfer roll placed after the last nip presses against the center roll at the point of separation of the web, and the suction transfer roll and the center roll A transfer felt for the suction transfer roll is introduced through a nip between the nip, and the web is transferred to the surface of the transfer felt by the vacuum force generated in the suction sector of the suction transfer roll located at the nip. with the support of a transfer felt in front of the web, for example into the drying section of a paper machine, using a waterless sealing roll in the area adjacent to the web for the suction transfer roll; It is characterized in that a higher suction occurs in the edge area of the outer shell of the suction transfer roll than in its central area.

Pick-up felts and suction rolls acting therewith are devices known in the prior art for transporting a wet web from the screening section of a paper machine to the press section.

However, the design and mode of operation of conventional suction rolls, which are similar to those of screen suction rolls or suppressor suction rolls and are used for separating webs from screens, are not suitable for use in press sections.

This is due to the design and working principle of the roll.

The suction roll has a length equal to the length of the barrel having the set of eyelets and has a suction box in the barrel with the eyelets connected to a suction device.

The suction box is provided with a sealing foil pressed against the inner surface of the roll cylinder.

In order to reduce the overall wear of the foils and their friction, water is sprayed on the inner surface of the suction rolls.

The amount of sealed water is 50 liters per minute per meter.

This part of the water is thrown off by centrifugal force through holes in the body of the roll and ends up in the paper web in the pick-up felt and membrane.

Additionally, defective nozzles on the spray tube may cause the water to be distributed unevenly across the width of the paper machine or across the length of the roll, which is detrimental to web temperature variations. No impact.

When separating the web from the screen, the web has such a high moisture content that the introduction of sealing water into the pick-up felt and partly into the web usually does not have significant consequences.

On the other hand, if the press is of conventional design and uses suction rolls for separation, the amount of sealing water is squeezed out of the paper web in the final pressing nip. Large compared to the amount of water released, the sealed water deteriorates the effectiveness of the suppression zone.

For example, if the speed of the paper machine is 800 m/min and the basis weight of the web is 509 m/min, the ratio of the dry component weight of the web to the total weight of the web increases from 37% to 40% at the last nip. If increasing, this means that water leaves the web in the nip at a rate of approximately 8 liters per minute per meter of paper machine width.

However, an equal or greater amount of water will be reintroduced into the web from the seal water of the separating suction roll after the last nip.

The separating suction roll placed in the press section cannot have a large diameter.

The small diameter of the roll creates a large centrifugal force, and that large centrifugal force is the reason why a large amount of water is released into the water.

In order to eliminate the above-mentioned disadvantages, the web processing device according to the invention provides that the suction transfer roll has a body in a sandwich-like configuration, an outer body having holes in at least one part and an inner side without holes. and a suction chamber between them, characterized in that a sector of the chamber is connected to the suction device by a fixed suction chamber end piece in combination with the suction transfer roll.

As mentioned above, a significant number of cuts that occur upon separation of the web from the press begin at the edges of the web.

This is because the edges of the web are somewhat uneven and less strong as a result of unsatisfactory interaction between the headbox and the screener.

The fragility of the edges of the web is due, in part, to air currents created by rotating rolls, etc., which cause the web to sway.

In the method according to the invention, the aim is therefore to ensure separation of the edges of the web by exerting suction forces primarily in the end areas of the roll cylinder.

In order to avoid unnecessarily loading the vacuum system, suction may be largely omitted in the central area of the web if this is possible taking into account the runnability and quality of the paper being produced.

In order to deal with the so-called blowing phenomenon (air entering between the wet paper and the felt), the separation roll may be provided with a miso or blind hole in the center, and the blind hole will not penetrate through the outer part. .

A set of blind holes with a hole spacing and a diameter corresponding to the set of through holes in the end area of the cylinder is such that the effect of the set of holes on the paper in the form of a mark that can be more or less luminous is the same throughout the web. preferable.

It will become clear later that the hole embodiment can be done in a number of different ways.

Certain suction rolls with cellular structures are known, for example, from Finnish Patent No. 18972.

Such suction rolls have traditionally been used as suction rolls in the screening section of paper machines, but the dewatering capacity of these suction rolls has traditionally been limited, and due to their structure, suction rolls do not place extra load on the vacuum equipment. Conventionally given.

If a cellular suction roll is used in the embodiment according to the invention, the dewatering capacity of the suction roll is of no importance; It is important to create a vacuum.

It is true that with a certain special constructional design of the cellular suction roll according to the invention very low air consumption is obtained.

Such a design will be described later. This is not only due to the amount of air passing through the web facing the suction area (but also due to the amount of air fed into the suction area through holes or chambers in the suction o-le, which is fed to the suction pump connected to the suction roll). Load is affected.

The thicker the body of the suction roll with its collection of holes, or the larger the chambers of the suction roll, the more air will be forced into the suction device to create a sufficient vacuum to keep the web tight. In addition to the air passing through the paper web or felt, it must be removed to obtain

A small amount of extra air also goes to the suction device from the point of leakage in the seal.

In the cellular suction roll according to the invention, the amount of excess air is minimized by limiting the combined capacity of the outward holes and the suction roll chambers by means of the structure that will become clear from the description of this example. can do.

The invention will now be described in more detail with reference to the accompanying drawings.

The invention is in no way limited to these.

The first method to which the method and apparatus of the present invention can be applied particularly advantageously.
The press section shown in the figure has a central roll 1 with a relatively large diameter.
Has 0.

Limited by the first clamping part of the suppression area L12,
Of these rolls, roll 11 is a suction roll, and roll 12 is a roll with a dimpled surface, such as a rolled roll with a beaded surface.

Each roll lL12 has each felt roof "l4, 13
so that the web W has two felt loops 13
, 14 and passes through the first sandwiching portion N1.

The suction roll 11 together with the central roll 10 defines the second nip N2 of the suppression part.

The third nip N3 is defined by a central roll 10 and a pressure roll 15, the pressure roll 15 being provided with its own felt loop 16, the guide roll of which is indicated by the reference numeral 18.

The press section also has a fourth jaw section and a fifth jaw section (not shown).

The position of the suction transfer roll 20 according to the invention is clear from FIG.

This suction transfer roll 20 is provided with a felt loop 19 of its own transfer or pick-up felt, a felt loop 190 guide roll being shown at 18.

According to the invention, the suction transfer roll 20 is pressed against the central roll 10 of the press section at the point of departure of the web W, thereby transferring the web W to the felt loop or transfer felt 19, and the web W is pushed onto the suction transfer roll 20. It comes into close contact with the transfer felt 19 due to the vacuum force acting on the suction sector α (FIG. 4).

The web W supported by the transfer felt 19 is further introduced into the drying section of the paper machine.

Place the transfer felt 190 guide roll 17 as close as possible to the suction transfer roll 20.

It is further important to the process of the present invention that the suction transfer roll 20 be a cellular suction roll that requires sealing water only at the ends and not elsewhere, and a preferred construction will be described later.

The suction transfer roll 20 of FIGS. 2.3 and 4.5 has two coaxial cylinders 2L22 with a chamber 32 between them.
There is a body 22 inside, and a small chamber 32 is connected to a partition wall 3 in a generally radial direction.
4.

The outer part 21 has a set of holes 33, the material of which is, for example, bronze or stainless steel.

The outer 21 has the same thickness.

The inner steel 22 most suitably consists of a steel tube, machined so that it is conical, so that the outer steel 21 and the inner steel 2
2 and the cross-sectional area of the chamber 32 is smaller in the center than at the ends of the chamber 32.

The partition wall 34 may be made of steel or other suitable material, for example.

The partition wall 34 can be arranged in a spiral shape in the space between the outer steel 21 and the inner steel 22.

The chamber 32 defined by the partition wall 34 is narrow and long, and extends continuously from the center to the ends of the suction transfer roll 20 and opens at the ends.

The suction transfer roll 20 is provided with a fixed suction chamber end piece 27 at both ends or only at one end, and when the suction chamber end piece 27 is provided at only one end, the small chamber 32 is attached to the suction transfer roll 20. Close at the other end.

The suction chamber end piece 27 accommodates a conduit 28, the width of which determines the number of chambers that communicate with the suction chamber (arrow B) at any given moment, i.e. the width of the conduit 28 determines the suction fan shape at the surface of the suction transfer roll 200. Determine the width of body α.

Bearings 25,26 for the shaft 23 of the suction transfer roll 20
is combined with the suction chamber end piece 27.

The suction chamber end piece 27 has a seal 31 around its suction orifice 28 (suction sector α).

Correspondingly, the rotating suction transfer roll 20 carries an annular seal 30, which in combination defines a sealing surface 29.

A support shaft 35 is provided at the center A-A of the suction transfer roll 20 between the outer steel 21 and the inner steel 22, and the suction transfer roll 20
has suction chamber end pieces 27 at both ends thereof in these embodiments.

The shaft 23 and the inner steel n are interconnected by an intermediate member 24.

Regarding the structural design of the outer body 21 and the collection of eyelets on the outer body, several variations can be envisaged to achieve the objectives of the invention.

For example, the following embodiment is possible.

a) A collection of small holes are provided uniformly throughout the body, and all the holes pass through the outer part 21.

Cell-like structures extend outwardly throughout.

b) A collection of small holes are provided uniformly throughout the body, but some holes in the center of the body are so-called blind holes;
The blind hole cannot penetrate the body.

The cellular structure extends throughout the torso.

C) The barrel is provided with a uniform collection of small holes throughout, but all the holes in the center are blind holes.

The through holes are only in the end area of the barrel. Cellular structures correspond only to areas with through holes.

d) The collection of eyelets in the through-hole is sparse in the central part, and the collection of eyelets in the end areas of the body is more through-hole.

e) The body has a through hole at the end and a hole in the center of the body.
Finnish Patent No. 4558 by the applicant of this application
Uneven band material 36 rolled as described in Specification No. 3
Provide groove 37 made with.

In that case, the cylinder 32 does not extend to the central part of the suction port 20.

f) The central part of the barrel shall be provided with a groove providing a smooth, non-perforated surface.

At both ends of the body, there are a collection of small through holes in two areas, and the hole area at the outermost end is, for example, 20-25%, and the hole area at the next area is 10-15% or more. smaller.

The number of holes or the overall hole area required depends, for example, on the type of paper to be produced and the quality of the felt or dry fabric used with the suction transfer roll.

A dense set of holes is here considered to be a set of holes where the total area of independent holes on the roll surface is 20% to 25% or more of the area on each side.

A given independent hole area can be obtained by providing a large number of small holes or a small number of large diameter holes.

A sparse hole collection is considered hereinafter to be a hole collection that is about 10-15% of the lateral area or smaller.

Cellular structure 32.3 between the outer steel 21 and the inner steel 22
4, the following preferred embodiment is considered.

a) The partitions 34 of the chambers 32 are radial and parallel to the axis of the roll, and the chambers 32 have a constant height and width and thus a constant cross-sectional area over the entire length of the suction transfer roll 20.

b) The chambers 32 are parallel to the axis of the suction transfer roll 20 and the height of the chambers 32 is smaller in the middle than at the ends.

C) The partition wall 34 of the chamber 32 forms a gentle helical shape starting at the center of the suction transfer roll 20.

d) The small chambers 32 are present only at the ends of the suction transfer roll 20 in the perforated portion of the outer portion 21 of the suction transfer roll 20.

As identified in the foregoing features, the following design features of the cellular suction transfer roll 20 reduce excess air and parasitic air.

a) 1) by reducing the number of holes 33 passing through the outer 21 to be as small as possible; 2) by using a thin outer 21 (this reduces the necessary strength of the suction transfer roll 20) This is possible since it can be obtained with the help of side 22) to obtain the capacity of a small hole for the outside.

b) Sizing the chamber 32 entirely in terms of airflow so that the chamber 32 has a small height and the cross-sectional area of the chamber 32 is equal to the combined cross-sectional area of the holes in the corresponding suction area; So small chamber capacity is possible.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the processing method according to the present invention when applied in a press section where only wet paper having three sandwiching sections is arranged in order and does not run; An axial sectional view of the suction transfer roll and a partial sectional view taken along line I--I in FIG. 4, FIG. 3 is a partial sectional view of the end of the suction transfer roll in FIG. 1, and FIG. 2 is a plan view of the suction transfer roll as seen in FIG. 2, and FIG. 5 is a partial sectional view of a variant embodiment of the suction transfer roll according to the invention with a chamber and an outer section. In the figure, W is the web, α is the suction sector, N1°N2
, N3 is a clamping part, 10 is a central roll, 20 is a suction transfer roll, 21 is for the outside, 22 is for the inside, 27 is a suction chamber end piece, 32 is a small chamber, 33 is a hole, 34 is a partition, 35 is a pillar export.

Claims (1)

[Claims] 1. The press part is at least two continuous nipping parts N2.
, N3 with a smooth-surfaced central roll 10 defining the rolls 11.15, preferably with a first sandwich of double felt between the recessed-faced roll 12 and the suction roll 11 in the press section. This suction roll 11 is connected to the second part of the press part N1 together with the central roll 10.
A rotating suction transfer roll 20 is used for web processing to limit the pressure nip N2 and to separate the paper web W from the central roll 10 and to guide the web W further forward.
In the web processing method in the press section of a paper machine using The felt 19 of the suction transfer roll 20 is introduced through the nip between the suction transfer roll 20 and the center roll 10, and the felt 19 of the suction transfer roll 20 is introduced into the suction sector α of the suction transfer roll 20 located at the nip. The web W is transferred to the surface of the transfer felt 190 by the vacuum force and brought into close contact therewith, and with the support of the transfer felt 19, the web W is guided forward to, for example, a drying section of a paper machine, and the web W is used for the suction transfer roll 20. Using a sealing waterless roll in the adjacent area, suction transfer roll 2
A method for processing a web in a press section of a paper machine, characterized in that a higher suction is produced in the edge area of the outer side 21 of the paper than in its central area. 2. Claim 2, characterized in that the amount of air drawn per unit area of the shell of the suction transfer roll 20 through it decreases stepwise from the ends of the suction transfer roll 20 to its central part. The web processing method according to item 1. 3. The web processing method according to claim 1 or 2, characterized in that no suction force acts on the central portion of the outer side 21 of the suction transfer roll 20. 4 At least two consecutive press parts N2
, N3 with a smooth-faced central roll 10 defining the roll 11.15, preferably with a double felt first sandwich between the recessed-faced roll 12 and the suction roll 11 in the press section. A rotating suction transfer roll 20 is used for web processing to limit N1 and separate the paper web W from the central opening 10 and to guide the web W further forward, and the final press nip Part N2, N
The suction transfer roll 20 placed after 3 presses against the center roll 10 at the separation point of the web W, and the felt of the suction transfer roll 20 passes through the nip between the suction transfer roll 20 and the center roll 10. 19 is introduced, and the web W is transferred to the surface of the transfer felt 190 by the vacuum force generated by the suction fan-shaped body α of the suction transfer roll 20 located at the nip portion, and is brought into close contact with the surface of the transfer felt 190 and is supported by the transfer felt 19. to guide the web W forward, for example into a drying section of a paper machine, using a sealing water-free roll in the area adjacent to the web W for the suction transfer roll 20 on the outer side of the suction transfer roll 20. Press of a paper machine, in which the suction transfer roll 20 which, together with the central roll 10 defines the nip, is a suction roll with cellular structures, in order to produce a higher suction in the edge area of 21 than in its central area. In the web processing device in the department,
The suction transfer roll 20 has a body in a sandwich-like configuration, which has an outer side 21 provided with a set of holes on at least one part, an inner side 22 without holes and a suction chamber between them. , a web processing device in a press section of a paper machine, characterized in that a given sector α of the chamber is connected to the suction device by a fixed suction chamber end piece 27 which is associated with a suction transfer roll 20. 5 The outer side 21 is provided with a set of holes evenly distributed over its entire surface, with holes 3 in the central part of the outer side 21
5. A web processing device in a press section of a paper machine according to claim 4, characterized in that 3 does not extend through the outer side 21. 6. According to claim 4, the arbitrary cross-sectional area of the set of holes passing through the outer side 21 is smaller in the central part at both ends of the suction transfer roll 20 than in the part closer to the end faces. A web processing device in the press section of a paper machine. 7. The web processing device in a press section of a paper machine according to claim 4, wherein the central portion of the outer body 21 of the suction transfer roll 20 is not provided with a hole. 8. A web processing device in a press section of a paper machine according to claim 7, wherein the central portion of the outer side 21 is smooth. 9. A web processing device in a press section of a paper machine according to claim 7, characterized in that a groove is provided in the central portion of the outer side 21. 10 The part where the miso is provided on the outer side 21 is rolled up (
(FIG. 5) A web processing device in a press section of a paper machine according to claim 9, characterized in that it is made of a strip material 36 having unevenness. 11. Press of a paper machine according to any one of claims 4 to 10, characterized in that the cellular structures are only in the perforated area of the body of the suction transfer roll 20. Web processing equipment in the department.