JP2003515685A - Web support method and web support device - Google Patents

Abstract

(57) [Summary] In a press section of a paper machine or a paperboard machine, the movement of a web in a linear transfer section from a roll (23) to a second roll (31) while being supported by a fabric (20) is stabilized. Methods and equipment. According to the web support device (60) according to the present invention, the vacuum effect is enhanced in important areas such as an open gap and a closed gap, and in both edge areas of the web (W). In these areas, higher speed blowing is applied from the discharge nozzles (61a, 61b, 62a, 62b) and / or suction slots (63a, 63b) are connected to these areas to enhance suction. Vacuum effects in the wide center area as the web is traversed longitudinally and laterally are suppressed by providing a controlled leak flow (64) or a vacuum damping flow implemented by limited counter blowing. This concentrates the greater vacuum effect in the vicinity of the fabric support rolls (23, 31) and their edge areas.

Description

Detailed Description of the Invention

The present invention relates to the linear movement of the movement of a web from a first roll or its equivalent to a second roll or its equivalent, while being supported by a fabric, in the press section of a paper or board machine. The present invention relates to a method for stabilizing the transfer section.

The invention further relates to the linear movement of the movement of the web from the first roll or its equivalent to the second roll or its equivalent, while being supported by the fabric, in the press section of the paper or board machine. It relates to a web support device which is particularly suitable for stabilizing in a profile transfer section.

The present invention also relates to, in the press section of a paper machine or a paper board machine, the movement of the web from the vacuum transfer roll or its equivalent to the press nip while being supported on one side only by the fabric in its linear transfer section. It relates to a stabilizing method.

Opti is characterized in that the web is transferred in a substantially straight line over the entire press section.
In the Press ^TM type press section, so-called felt vacuum rolls and felt vacuum transfer rolls are used to transfer a paper web or paperboard web from one fabric to another. Between these rolls, or after these rolls, the web is sandwiched between two fabrics along a straight track, or supported by only one fabric, utilizing a blow box or suction box. Sent. These boxes generate a negative pressure field in the space between the fabric and the box by ejecting or direct suction.

A problem with blow boxes known from the prior art is that the vacuum effect they create between the fabric and the web is relatively weak. This is because the press felt, in particular, has a floc layer and a high water content, which makes it rather impermeable at the currently used vacuum. A second problem is that the fabrics used for linear transfer have a much longer support distance and the fabrics have limited tension. For this reason, the blow box causes the fabric to be significantly curved in both the vertical and horizontal directions. Due to the curvature in these two directions, the web will also need to be stretched differently in the center compared to its edges. The web may slide, at least in part, over the surface of the support fabric, which may cause the web to slip out of the fabric and sag. Furthermore, in transport prior to the press nip, when a steam box is used to increase the squeeze temperature of the web to enhance dewatering, fabric and web bending are detrimental in the steam heating zone. This is because the steaming distance is not constant.

In high-speed paper or board machines, the air flow trying to pull the web away from the fabric is strong. Open and closed gaps require the web to be tightly attached to the fabric and both edges of the web are
Do not leave the fabric at any stage of the press section. This is because otherwise the runnability of both the press section and the drying section will be problematic. The need for negative pressure is thus different at various stages of support. The highest levels of negative pressure are required at the open and closed gaps and at both edges of the web, whereas in the central portion of the support area the negative pressure is small enough to keep the web attached to the fabric. Is enough. However, the blow suction box technology used today can only maintain a substantially uniform degree of vacuum in all areas affected by the blow suction box.

US Pat. No. 4,757,619 discloses a suction transfer device intended for use in transferring a web from a press section to a drying section. It also exerts a greater vacuum effect on both edge areas of the web than in the center of the web. According to this, along the running direction of the web, the negative pressure profile is substantially equal over the transport distance.

The present invention aims to develop a new scheme for supporting the web and stabilizing its transport, thereby minimizing the problems associated with the techniques known from the prior art. The aim is to allow the web to remain tightly adhered to the fabric even at high speeds and yet to reduce the harmful bending of the fabric in the support space.

In order to achieve the objects mentioned above and below, the method according to the invention is characterized by what is stated in the characterizing step of claim 1. Next, a web support device according to the invention is characterized by what is stated in the characterizing stage of claim 3. Various applications of the method and the device of the invention are further characterized by what is stated in the independent claims 13 and 14.

According to the method according to the invention, a vacuum effect is exerted on the fabric which guides the movement of the web from the first roll to the second roll, the size of which changes in the support area between the rolls. . That is, the negative pressure at the beginning of the support distance and in the area of the gap opening between the first roll and the fabric, and at the end of the support distance and in front of the second roll, respectively, Substantially greater than the negative pressure affecting the central area between them. In order to achieve this, the web support device according to the invention comprises means for applying a large local negative pressure in the gap between the web support device and the fabric in the front edge area of the web support device and the web support device. Means for applying a large local negative pressure in the gap in the trailing edge area,
Means for applying a negative pressure to the gap in the central region of the web support device that is substantially less than that described above. Desirably, also on both ends of the web support device are members arranged to deploy a large negative pressure in the edge area of the web.

With the web support device according to the invention, the vacuum effect is enhanced in important areas such as open and closed gaps, and preferably in the edge areas of the web. Faster blowouts than before from these discharge nozzles towards these areas and / or suction slots which increase their negative pressure are connected to these areas. In the large central area of the web in the machine and transverse directions, the vacuum effect is suppressed by providing a controlled leak flow or by providing a vacuum dampening flow provided by a limited counter blow. In this way, a greater vacuum effect than before is exerted in the vicinity of the support roll and edge areas of the fabric. On the other hand, a lower negative pressure than before is created in the central area, which reduces the harmful bending of the fabric, but this negative pressure is sufficient to keep the web attached to the fabric. Advantageously, the negative pressure at the edge of the web support is about 500 to 4,000 Pa and in the central area about 50 to 400 Pa.

According to one embodiment of the invention, the desired negative pressure profile in the support area between the rolls is achieved by arranging a number of successive web support devices at that support distance, the first of which is , A member that produces a large local negative pressure at the beginning of the support distance, the last of which includes a member that produces a large local negative pressure at the end of the support distance and all devices are It includes members that produce a negative pressure in the area that is less than that described above.

The web supporting method and the web supporting apparatus according to the present invention can be used not only for transfer in the press section, but also for use in other places of the papermaking line such that the web is well held on the drying wire at the start of the drying section. Is also suitable. Other possible uses are
For example, in a flat-type impingement drying device, the web is supported by a permeable drying wire, and in a surface treatment device, the web is supported by a conveyor.

The present invention will now be described in more detail with reference to the accompanying drawings, but the present invention is not limited to the contents thereof.

FIG. 1A shows a press section marketed by the Applicant under the product name OptiPress ^™ . This includes two press nips, the first of which is the roll nip N ₁ and the second of which is the extended nip N ₂ . The press section further comprises three press felt loops 10, 20 and 30 which absorb water and one transfer belt loop 40 which does not absorb water, whereby the web W is pressed along a relatively straight track. It is guided through the nips N ₁ and N ₂ to the drying section.

At the end of the former section, the web W is transferred from the wet wire 5 onto the first upper felt 10 by the pickup roll 11. The web W from the pick-up roll 11 is supported by the upper felt 10, is guided to the felt roll 21 that guides the stroke of the lower felt 20, and is further sandwiched between the felts 10 and 20, and the two press rolls are pressed against each other. It is guided to the _first press nip N ₁ created between 12 and 22. After this nip N ₁ , the stroke of the upper felt loop 10 is guided by the felt roll 13 and the stroke of the lower felt loop 20 is guided by the felt vacuum roll 23 and the felt roll 24, and their combined effects affect the web. W is separated from the upper felt 10 after the felt vacuum roll 23 and follows the lower felt 20. From the linear travel of the lower felt 20, the web W is transferred by the vacuum transfer roll 31 to the underside of the second upper felt 30 and carried by the felt 30 to the guide roll 41, where the web W is transferred belt. 40
Contact the upper surface of. Web W has an upper felt 30 and a transfer belt 40.
While being held in contact with the felt roll 33, it is guided to the _second press nip N ₂ formed between the extended nip roll 32 and its back roll 42 which are in pressure contact with each other. To the upper felt 30 to avoid being wetted again immediately after the nip N ₂ by absorbed water, the upper felt 30 is guided away from the web by the felt roll 34 immediately after the extended nip N ₂ . The web W is gripped by adhering to the surface of the transfer belt 40, and follows the belt 40 until being transferred onto the drying wire 50 by the vacuum transfer roll 51 before the guide roll 43. The drying wire 50 is fed to a drying section including a drying cylinder 52 and a reverse suction roll 53, as known from the prior art,
Guide the web.

FIG. 1A further shows an option for the steam box 35 arranged in the linear transfer part of the web W before the _second press nip N ₂ and the transfer part before the _first press nip N _1. And the position of a similar steam box 14 arranged as. The role of these steam boxes 14, 35 is to raise the temperature of the web W and to enhance the dewatering in the nip. In the drying section, a blow box 54 known from the prior art is used.
Which is located facing the reversing suction roll 53 in a pocket made between two drying cylinders.

In the case of the press section shown in FIG. 1A, four linear transfer sections work together and the wet web W is supported on only one side by the press fabric or the drying fabric. These transfer units are as follows. Pickup roll 11 supported by upper felt 10 to felt roll 21, felt vacuum roll 23 supported by lower felt 20 to vacuum transfer roll 24, upper felt 30
From the vacuum transfer roll 31 supported by the above to the induction roll 41, and from the vacuum transfer roll 51 supported by the drying wire 50 to the first drying cylinder 52 of the drying section. Blow boxes are typically located in the three locations described below and are generally designated in the figure by the letters B, C, D ₁ and D ₂ , which create a pressure differential between the two sides of the fabric, W adheres to the felt 20, 30 or wire 50. Although a blow box is not yet used in the transfer section after the pickup roll 11, the place where the web supporting apparatus A can be arranged is shown by a dotted line in the figure.

The present invention relates to a new type of web support device, which is advantageously
It can be arranged at any of positions A to D of 1A. Unlike the one shown in the figure,
If the perforated press felt is provided as a lower fabric in the second press nip N ₂ instead of a smooth impermeable transfer belt, the web support device is also used in the straight felt transfer section after the _second press nip N _2. It is possible, in which case the web is guided and supported on one side only by the felt.

Occasionally, the scheme in the area between the vacuum transfer roll 31 and the second press nip N _{2 of} FIG. 1A causes defects in the paper web. Therefore, FIG. 1B shows another method for transferring the web W from the lower felt 20 of the first press to the second press nip N ₂ . According to this design, the web W is a vacuum transfer roll.
After 31 it is supported by the upper felt 30 and fed to the second press nip N ₂ . The guide roll 41 that guides the travel of the transfer belt 40 is arranged away from the path of the web, and the web W and the transfer belt 40 do not come into contact until they enter the nip N ₂ . Between the transfer suction roll 31 and the nip N ₂ , the travel common to the web W and the fabric 30 includes the first web support device C ₁ , the support roll 36, and the second web support device C ₂ . Are arranged inside the press felt loop 30 and all together ensure a good support of the felt 30 on the entire support distance of the web W.

FIG. 1C replaces the support roll 36 of FIG. 1B with a web support device C _4, and provides three web support devices C ₃ , C ₄ , C ₅ in series within a support distance to stabilize the movement of the web. FIG. 2 shows another way of making all of these devices produce the supporting effect that one seeks to obtain with the present invention. A problem that arises with such schemes is that the steam heating distance of the steam box 35 is not constant due to the increased support distance. Therefore, the shape of the press portion shown in FIG. 1B is more advantageous.

FIGS. 2 and 3 show two prior art blow boxes 57 located in position B of FIG. 1A. According to these, the web W is fed after contacting the lower side of the second upper felt 30 while being supported by the lower felt 20 after the suction sector 23a of the felt vacuum roll 23, and this is transferred to the lower side of the vacuum transfer roll 31. It is attached by the effect of the negative pressure spreading in the suction sector 31a. In the linear transfer section between the felt vacuum roll 23 and the vacuum transfer roll 31, a blow box 57 is arranged inside the lower felt loop 20 in order to keep the web W and the felt 20 in contact with each other. The positive pressure p ₁ has spread. Blow box 57 has blowout nozzle slots 58a and 58b at the front and rear edges, which are
The space between the blow box 57 and the fabric 20 is oriented to blow air at high speed. In FIG. 2, the blowing nozzle slot 58a at the front edge of the blow box is oriented towards the gap opening between the roll 23 and the fabric 20, whereas the similar gap 58a in FIG. Directed against 23 surfaces. The powerful air blow-off creates an exhaust flow in the space between the blow box 57 and the fabric 20, in the front edge area of the blow box and also in the gap opening between the roll 23 and the fabric 20 from these spaces. The air is sucked out, and the negative pressure required to support the web W is generated. These nozzle slots 58a, 58b, which blow the air at the same blow pressure p ₁ , usually extend around the entire box 57 and into the areas on either side of it, with a negative pressure of substantially constant magnitude in the area of the blow box 57 as a whole. Cause Due to the negative pressure, the fabric 20 is blown
It bends and extends in both the longitudinal and transverse directions at the center of 57. The bend E of the fabric 20 is the straight line distance (broken line J) between the fulcrums and the fabric 20.
Of the actual runway, which is at most about 30 to 60 mm and is determined by the length of the bearing distance, the tension of the fabric 20 and the level of negative pressure created by the blow box 57.

FIG. 4 shows a web support device 60 according to the invention arranged parallel to the fabric 20 within the support distance between the felt vacuum roll 23 and the vacuum transfer roll 31, the web support device 60 and the fabric 20 A gap-like space 66 is formed between them. Over its entire length, the web support device 60 has four blowing nozzle slots 61a.
, 61b, 62a, 62b are provided so as to extend in the lateral direction with respect to the traveling direction of the fabric 20, and each is connected to a blowout air generation source (not shown) via respective air flow paths. . Due to these independent air flow paths, blown air at various pressures p ₁ , p ₂ , p ₃ and p ₄ is delivered to each blow nozzle slot 61a, 6a.
It can be fed into 1b, 62a, 62b. The first nozzle slot 61a is the device 60
Are located on the front edge of the web and the second blowout nozzle slots 61b are located on the back edge of the device 60, which are arranged to blow air from the web support device 60 at high speed. The third blow-out nozzle slot 62a is arranged at a distance from the first blow-out nozzle slot 61a, and the fourth blow-out nozzle slot 62b is arranged at the second blow-out nozzle slot 62a.
A small distance from the blow-off nozzle slots 61b, which are arranged to blow air at a constant velocity into the space 66 between the web support device 60 and the fabric 20, The speed of the first and second blowing nozzle slots 61
It may be lower than the air flow blown from a and 61b. The central area of the web support device 60 is provided with a first suction slot 64 or equivalent, through which the air blown from the nozzle slots 62a, 62b into the space 66 into the suction flow path. It is removed, but there is a negative pressure −p ₇ spreading there. Further, the web support device 60 has a second
Suction slots 63a, which are located on the front edge of the support device and are located in the space between the first and third blowing nozzle slots 61a and 62a. The web support device 60 further includes a third suction slot 63b located on the trailing edge of the support device and located in the space between the second blow nozzle slot 61b and the fourth blow nozzle slot 62b. Has been done. These suction slots 63a
And 63b by eliminating into the plurality of suction channel that extends the air negative pressure -p ₅ and -p _6, to enhance the vacuum effect in the region of the front edge portion and trailing edge portion of the device 60 It is arranged as follows.

The blown-out air stream terminating in the blow-out nozzle slots 61a, 61b, 62a, 62b converges at the end portion in the blow-out direction, and the outflow of air passes through the nozzle slots of about 0.5 to 4 mm to Or at a speed of 300 m / s. The dimensions of the nozzle slots at the front and / or the rear edges of the blow box may be of different sizes in the transverse direction of the paper machine, such as a large nozzle size in the edge area of the paper machine, or The large suction slot allows a large volume of air flow to be generated for the edge area. The large volume flow increases the vacuum effect that keeps the web attached to the fabric at the leading edge area and / or the trailing edge area. Areas with a large negative pressure, from the edge of the paper machine to the central area,
It may be extended by about 50 to 400 mm.

The air stream blown out at high velocity from the nozzle slot follows a curved surface terminating at the nozzle slot, which is typically a tube with a diameter of 40 to 80 mm. This air flow produces an exhaust effect that draws in outside air by the air jet. The airflow blown from the outermost nozzle slots 61a, 61b produces an exhaust flow that is excluded from the space 66 and from the open or closed gap. Innermost nozzle slot
The air flow blown from 62a, 62b creates an exhaust flow into the space 66 between the web support 60 and the fabric 20 from which the air exits via the suction slots 64. In this way, a negative pressure is created between the web support 60 and the fabric 20, which creates a pressure differential and a force that holds the web W tightly against the fabric 20. Suction slots on the front and back edges of web support 60
63a, 63b further enhance the vacuum effect in these areas.

The surface of the fabric 20 and the roll 23 should be very high in order to prevent negative pressure from escaping from both sides of the open gap between the roll 23 and the fabric 20, ie from the front edge of the web support. A sealing plate 65 is arranged in close proximity. Similar sealing plates may be placed on either side of the rear edge of the web support apparatus 60 at any time to seal the gap being closed, as shown in FIG. 6A, if desired.

Advantageously, the edges on each side of the web support device 60 are also provided with blow-out and suction-slot equipment of the type described above, as will be described below in connection with FIG.

FIG. 5 shows the shape of the negative pressure field generated in the space 66 by the web support device 60 according to the present invention. In this embodiment, spread negative pressure -p _a of equal magnitude to the leading edge portion and trailing edge portion of the web support apparatus, spread on the negative pressure -p _b is the side edges,
A substantially uniform underpressure -p _{c, which} is clearly smaller than the underpressures -p _a and -p _b extending over the edges, extends over a large central zone. Negative pressure -p _a impact on the leading edge portion and trailing edge portion of the device need not necessarily be sized equally, depending on where you require greater support, stepwise It can be changed. For the same reason, the fabric and the negative pressure affects the edge zone of the web -p _b also different from the negative pressure -p _a impact on the leading edge portion and trailing edge portion region of the device 60 Can be

Alternatively, the negative pressure on the leading edge and / or the trailing edge changes the size of the nozzle slot, and a larger negative pressure −p _a ′ and −p _a ″ is applied, for example, on the leading edge and / or the trailing edge. Profiling can be done by concentrating on the side regions of the edge. Generally, the edge areas of the open and closed gaps have a greater need for fabric support of the web than the central area.

FIG. 6A shows first press fabrics 10, 20 to second press fabrics.
The transfer of the web W to 30 and 40 while being supported by the web supporting devices 60B and 60C is shown. The 1st apparatus 60B is arrange | positioned at the transfer part between the felt vacuum roll 23 and the vacuum transfer roll 31 similarly to what is shown in FIG. The second device 60C is disposed between the vacuum transfer roll 31 and the guide roll 41 for guiding the traveling of the transfer belt 40, and the negative pressure influence area generated by the web supporting device 60C is the vacuum transfer roll. From the open gap between 31 and the fabric 30 to the inside of the closed gap between the felt roll 33 and the fabric 30. On the opposite side of the latter device 60C, a steam box 35 is arranged below the web W, which is arranged to blow steam to the underside of the web W, the temperature of the web before the subsequent pressing step. Is to raise. The pressure differential created by the device 60C between the two sides of the fabric facilitates the entry of steam 35 into the web W. In addition, the web support device 60C includes a fabric 3 in the support area between the rolls 31 and 41.
By reducing the zero and the bow of the web W, the steam heating distance is kept constant, which facilitates achieving a uniform end result.

FIGS. 6B and 6C show two other methods of supporting the web W, in which the web is guided by the vacuum transfer roll 31 to the fabric 30 and runs to the extended nip roll 32 and the backing. Directly into the press nip N ₂ made with the roll 42, without support by the transfer belt 40 (compare also FIGS. 1B and 1C). In FIG. 6B, a support roll 36 is placed in the middle of the support distance to prevent the press felt 30 from vibrating and bending within a relatively long support distance. This support roll 36 may be a smooth or grooved roll. Alternatively, a perforated roll that suctions from the entire circumference or a roll provided with a suction box may be used to form a narrow suction sector with respect to the fabric. The web support devices 60C ₁ and 60C ₂ according to the invention are arranged on both sides of the support roll 36, which are in the area of the front and rear edges of the device.
It is arranged to create a greater negative pressure in the central area of the device.

Also in FIG. 6C, the web W is fed from the vacuum transfer roll 31 along a straight path into the press nip N ₂ and by the support by the felt 30 alone, without the support of the transfer belt 40. Transfer suction roll
The stabilization of the transport of the web W between the 31 and the press nip N ₂ is regulated by three successive web support devices 60C ₃ , 60C ₄ , 60C ₅ , which support the web W on the fabric 30. A desired amount of negative pressure is created within the support distance. At the front edge portion of the first web supporting device 60C ₃ at the start portion of this supporting distance, a suction nozzle and a blowing nozzle that generate an increased negative pressure are provided, and a suction nozzle and a blowing nozzle similar to this are provided. It is also found on the edge portion after the last web support device 60C ₅ of the end portion of the support distance. The rear edge of the first device 60C ₃ ,
At the front and rear edges of the middle device 60C _{4 and at} the front edge of the last device 60C ₅ , simple blow nozzles of the prior art are arranged to generate a small negative pressure in the central area of the support distance. To do.

Two boxes are provided between the vacuum transfer roll 31 and the press nip N ₂ .
Alternatively, only one long box may be used, whereby a large vacuum zone is created in the area of the open gap of the transfer suction roll 31 and the closed gap of the press nip N ₂ .

FIG. 7 shows the vacuum effect that stabilizes the stroke of the web W provided with the web support device of FIG. 6A. According to the drawing, on the two support distance, the area of the open gap at the beginning of the support distance, in the region of the closed gap at the end portion of the support distance, the maximum negative pressure -p _a, whereas, in the central zone of the support distance, it can be seen that a negative pressure -p _c clearly smaller than the negative pressure -p _a both-edge area.

FIG. 9 shows a side view of the method of the web supporting device according to the present invention, and FIG. 8 shows the shape of the negative pressure field generated thereby. On both side edges of the web supporting device 60, two blowing nozzle slots 67 and 68 are provided toward the ends,
Outer blowing nozzle slots 67 are respectively arranged to blow air from the web support device 60 at high speed, and inner blowing nozzle slots 68 are provided in the space 66 between the device 60 and the fabric 20. It is arranged to blow air into the inside. An air flow is generated from the outer blowing nozzle slot 67 at a pressure p ₁ , which is most advantageously greater than the pressure p _{2 of the} air flow expelled from the inner nozzle slot 68. In the central area of the web support device 60, a suction slot 64 is connected to a negative pressure source via which air is removed from the space 66 between the device 60 and the fabric 20. A suction slot 69 is arranged between the ends of the air passages of the outer and inner blow-out nozzle slots 67 and 68, by means of which the slot 69 creates a negative pressure effect in the area of the side edges of the web support device 60. It can be strengthened. Negative pressure −p ₃ spreads in the suction flow path terminating in the suction slot 69, and negative pressure −p ₄ spreads in the suction flow path terminating in the suction slot 64. By selecting these negative pressures to a desired magnitude, the desired negative pressure profile is achieved. According to the method proposed above, the negative pressure field shown in FIG. 8 can be generated in the space 66 between the web supporting device 60 and the fabric 20, and the vicinity of both edges of the web W in the negative pressure field can be generated. The negative pressure prevailing over −p _b can be greater than the negative pressure prevailing over the central area of the web −p _c .

As a comparison target, FIG. 10 shows a negative pressure. This can be generated by the prior art blow box 57 shown in FIG. Blow box 57 is provided on both side edges with blow nozzle slots 58 which expel air from box 57 at high speed and are arranged so that a substantially uniform negative pressure -p is spread over the entire area of space 66. Has been done.

The negative pressure distribution which is uniform in the lateral direction of the paper machine shown in FIG. 10 is considered as one option in the web supporting apparatus of the present invention when suction that strengthens the negative pressure at both edges is not used. You may

12 and 13 show a variation of the web support device of FIG. 6A. In this variation,
The outer nozzle slot 61a at the front edge of the web support device 60B ', 60C' has a device 60B '
, 60C ', and blows air toward the surface of the roll 23 or 31 that forms the open gap. In FIG. 13, the blowing nozzle slot 61b at the rear edge portion of the web supporting device 60C ′ is similarly arranged on the rear wall of the web supporting device 60C ′, from which the surface of the roll 33 constituting the closed gap is formed. Blow out a stream of air. By arranging the blowing nozzle 61a in this way and blowing out the surface of the roll, the roll 23
The open gaps after and 31, that is, the places where the negative pressure is most quickly required, can be generally negatively changed. However, as a result, the sealing side plate 65 becomes indispensable. The method described above is particularly advantageous for rolls having large dimensions. This is because the use of such rolls narrows the open gap and prevents the nozzle from entering the gap too deeply.

FIG. 14 shows another embodiment of the web supporting device. According to this, blow-out nozzle slots 81a and 81b are provided on the front edge portion and the rear edge portion of the device 80, from which the air flows of the pressures p ₁ and p ₂ increased via the blow-out nozzle flow paths. Supplied.
Air is blown away from the web supporting device 80 at high speed through the blowout nozzle slots 81a and 81b, and a negative pressure is achieved based on the discharge effect. Inside the gap 66 near these blowing nozzle slots 81a, 81b, a flow resistance means 82 is arranged on the surface of the web supporting device 80 parallel to the slots 81a, 81b, whereby the center of the web supporting device 80 is arranged. The discharge effect of air blowing in the area is limited, resulting in space 66
Generation of negative pressure in the interior is suppressed. For the flow resistance device 82, for example, a lath,
Rods or tubes may be used. A blowing nozzle and flow resistance means similar to this are also advantageously arranged at the end of the web support device 80. Furthermore, the central area of the web support apparatus 80 is provided with an air passage 83, which is connected to any to the source of positive pressure (+ p ₃₎ or negative pressure (-p _3), thereby, flow resistance A desired amount of negative pressure can be maintained in the central area of the web support device 80 left between the devices 82. By exerting a suction action on the space between the blowing nozzles 81a, 81b and the flow resistance means 82, it is possible to enhance the vacuum effect on the web. The negative pressure of the suction flow flowing into the above space is shown in FIG. 14 by arrows -p ₄ and -p ₅ .

FIG. 15 shows a third embodiment of the web supporting means. According to this, the force pulling the web W towards the fabric 20 is generated by a direct suction action via suction slots 91a, 91b arranged at the front and rear edges of the web support means 90, these slots being Negative pressures -p ₁ and -p ₂ flow into the inside through the suction flow path.
Desirably, similar suction slots are also provided on both sides of the web support means 90 to support both edges of the web W. Air passages 92 in the central area of the web support means 90.
Is provided and can be optionally connected to a source of positive pressure (+ p ₃ ) or negative pressure (−p ₃ ), whereby the negative pressure level in the center of the space 66 is adjusted to both edge areas of the web supporting means 90. It is adjusted to a level lower than the negative pressure at.

The range of use of the web supporting device is not limited to the press section. A paper machine in which the web is supported by a fabric and conveyed and a negative pressure is used to support the web is suitable for use in other positions. One possible use is shown in Figure 1A. According to this, in the linear transfer section from the vacuum roll 51 to the drying cylinder 52, the traveling of the web supported by the drying wire 50 is stabilized by the blow boxes arranged at the positions D ₁ and D ₂ . The first device D ₁ is preferably the device 60 of FIG. 6C.
Similar to C ₂ , each member is in accordance with the present invention arranged in the front edge of the device D _{1 in} a space open between the vacuum transfer roll 51 and the drying wire 50,
Generates a large local negative pressure. The second device D ₂ may be similar in structure to the device 60C ₂ or 60C _{3 of} FIG. 6C. That is, a conventional blow box or web support device that produces a uniform negative pressure is conceivable, after which the edge area is provided with a member that creates a large local negative pressure at the end of the support area. Desirably, the first
Nozzle equipment according to the invention can also be provided on both sides of the web support device D _{1 in accordance with} the invention, whereby a negative pressure can be created and the web can be supported on the fabric.

In addition to the web support device according to the present invention, for example, the web may be supported by a permeable drying wire in a flat impingement dryer, or the conveyor fabric associated with a surface treatment device may support the web. It can also be used.

[Brief description of drawings]

FIG. 1A is a diagram showing a press section of a paper machine and a position where a blow box / web supporting device can be arranged in the press section.

1B and 1C are views of another press section scheme for transferring the web to a second press nip in a different manner than that shown in FIG. 1A.

2 and 3   It is a figure which shows the blow box of a prior art.

[Figure 4]   1 is a schematic view of a web support device according to the present invention.

FIG. 5 is a view of a negative pressure field obtained by the web supporting apparatus according to the present invention as seen from a direction perpendicular to a fabric.

FIG. 6A is a diagram in which the movement of the web is stabilized by the web supporting apparatus according to the present invention while transferring the web from the fabric of the first press of the press section to the fabric of the second press.

6B and 6C are diagrams showing two other ways of stabilizing the movement of the web by the web supporting device according to the present invention while transferring the web from the fabric of the first press to the fabric of the second press in the press section. is there.

FIG. 7 is a view of a negative pressure field obtained by the web supporting device of FIG. 6A as seen from the lateral direction of the paper machine.

[Figure 8]   6B is a diagram showing the shape of a negative pressure field obtained by the web supporting device of FIG. 6A. FIG.

[Figure 9]   It is sectional drawing of the web support apparatus seen from the lateral direction of a paper machine.

[Figure 10]   FIG. 12 is a diagram showing a negative pressure field obtained by the web supporting device shown in FIG. 11.

FIG. 11 is a view of a system of a web supporting device that generates a uniform negative pressure field in the transverse direction as seen from the lateral direction of the paper machine.

12 and 13:   FIG. 6B is a view showing a modified example of the web supporting device of FIG. 6A.

FIG. 14   It is a figure which shows the web support apparatus of a 2nd Example.

FIG. 15   It is a figure which shows the web support apparatus of a 3rd Example.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE, TR), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, G M, KE, LS, MW, MZ, SD, SL, SZ, TZ , UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, B Z, CA, CH, CN, CR, CU, CZ, DE, DK , DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, J P, KE, KG, KP, KR, KZ, LC, LK, LR , LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, R O, RU, SD, SE, SG, SI, SK, SL, TJ , TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW

Claims (14)

[Claims] 1. A fabric in a press section of a paper machine or a paper board machine (
20. 30) stabilize the movement of the web from the first roll (23, 21) or its equivalent towards the second roll (31, 41) or its equivalent in the linear transport section of the web while being supported by the latter. In the method, a vacuum effect is exerted on the fabric (20, 30), the magnitude of the effect is varied in the area between the rolls, the beginning of the support distance being the first roll (23, 31). And fabrics (20, 30)
The area of the gap opening between the second roll (31,
In the front area of 41), a method of a negative pressure (-p _a), than the negative pressure affects the central zone that exists between those areas, characterized by substantially increased. 2. The method according to claim 1, wherein the fabric (20, 30).
), Changing the magnitude of the effect in the lateral direction of the fabric (20, 30) and the web (W), affecting the areas of both edges of the web (W). The method characterized in that the pressure (-p _b ) is substantially greater than the negative pressure (-p _c ) affecting the lateral central area of the fabric (20, 30). 3. A fabric (in a press section of a paper machine or a paper board machine)
The linear movement of the web (W) from the first roll (23, 31) or its equivalent to the second roll (31, 41) or its equivalent while being supported by the latter. Particularly suitable for stabilizing in part, arranged on the side of the fabric between the first and second rolls, over the substantially entire width of said web (W), the travel of said fabric (20, 30) And a space (66) is formed between the fabric (20, 30) and the web supporting device (60, 80, 90) and extends in a direction parallel to the fabric (20, 30). In a web supporting device (60, 80, 90) including a member for generating a negative pressure in a space (66) between the web supporting device (60, 80, 90), the web supporting device is the space (66). Of the web support device (60, 80, 90)
Means (61a, 63a, 81) for generating _a large local negative pressure (-pa) in the front edge region of the
a, 91a) and means (61b, 63b, 81b,) for generating _a large local negative pressure (-pa) in the rear edge area of the web support device (60, 80, 90) of the space (66). and 91b), means for generating in the central zone of substantially smaller negative pressure than a large local negative pressure (the web support device of the -p _c) the space (66) (60, 80 and 90) (62a , 62b, 64
, 82, 83, 92). 4. The web support apparatus (60) according to claim 3, wherein the apparatus further comprises a large local area in the area of the end of the space between the web support apparatus (60) and the fabric (20). A web supporting device comprising means (67, 68) for generating a negative negative pressure. 5. A web support device according to claim 3, wherein a first blowing nozzle slot (61a) is provided in the area of the front edge of the device and a second blowing nozzle is provided in the rear edge area of the device. Nozzle slots (61b) are provided, and the first and second blowout nozzle slots (61a, 61b) speed air from the space (66) between the web support device (60) and the fabric (20). The web supporting device (60) is provided with a third blowing nozzle slot (62a) after the first blowing nozzle slot (61a) on the surface of the web supporting device (60) facing the fabric. ,
A fourth blowing nozzle slot (62b) is provided in front of the second blowing nozzle slot (61b) on the surface of the web supporting device (60) facing the fabric, and the third and fourth blowing nozzle slots (62b) are provided. The blowout nozzle slots (62a, 62b) are arranged to blow air into the space (66) between the web supporting device (60) and the fabric (20), and The central section is provided with a suction slot (64) connected to a negative pressure source or its equivalent, which suction slot (64).
A web support device arranged to remove air from a space (66) between the fabric (20) and the fabric (20). 6. Web support device according to claim 5, characterized in that in the area of the front edge of the device a second suction slot (61a, 62a) is provided between the first and second blowing nozzle slots (61a, 62a). 63a) is provided, in the area of the rear edge of the device, a third suction slot (63b) between the second and fourth blowing nozzle slots (61b, 62b).
) Are provided and the second and third suction slots (63a, 63b) are configured to remove air from the space (66) near the front and rear edges of the web support device (60). A web supporting device, wherein the web supporting device is provided. 7. The web support device (60B ', 60C') according to claim 5 or 6, wherein the first blow-off nozzle slot (61a) comprises the web support device (60B ', 60C').
) Is located on the front wall of the first roll, thereby forming an open gap (
23, 31) A web supporting device, characterized in that air is blown against the surface of (23, 31). 8. The web supporting device (60C ′) according to claim 5.
), A second nozzle slot (61b) is located in the rear wall of the web support device (60C '), which allows air to be drawn against the surface of the second roll (33) forming a closed gap. A web support device, characterized in that a blowout of 9. A web support device according to claim 4, wherein two parallel blow-out nozzle slots (67, 68) are arranged in the areas of the ends of the device, the first blow-out of the slots. The nozzle slot (67) is arranged so as to blow air from the space (66) between the web supporting device (60) and the fabric (20) at a high speed, and is the second blowing nozzle slot of the slots. (68) is arranged so as to blow air into the space (66) between the web supporting device (60) and the fabric (20), and the air flow blown from the second blowing nozzle slot is A web support device characterized in that the velocity is lower than the velocity of the air stream blown out from the first blow-off nozzle slot (67). 10. The web support apparatus (60) according to claim 9, wherein both ends of the apparatus have suction slots (69) between the first and second blowout nozzle slots (67, 68). A web support device, wherein the suction slot is arranged to remove air from a space (66) near both ends of the web support device. 11. Web support device according to claim 3, wherein the device comprises a first blowing nozzle slot (81a) in the front edge region of the device and a second blowing nozzle in the rear edge region of the device. Slots (81b) are provided and the first and second blowout nozzle slots (81a, 81b) allow air to be rapidly drawn from the space (66) between the web support device (80) and the fabric (20). A sealing member (82) is arranged so as to be blown away, and a sealing member (82) is arranged on the surface of the web supporting device (80) toward the fabric (20), and the member is a traveling direction of the web (W). Is disposed so as to be transverse to the web supporting device (80), the member suppresses the discharge effect by the air flow at the front edge portion and the rear edge portion of the central area of the web supporting device (80), Air slots (83 Or its equivalent and the slot is optionally connected to either a negative pressure source or a positive pressure source, whereby the negative pressure in the central area of the web support device (80) is desirably adjustable. A web supporting device. 12. A web support device according to claim 3, wherein the device has a first suction slot (91a) in the front edge area thereof and a second suction slot (91a) in the rear edge area of the device. 91b) is provided and the first and second suction slots (91a
, 91b), air is expelled from the space between the web support device and the fabric, and an air slot (92) or its equivalent is provided in the central area of the web support device (90). A web support device, wherein the slot is optionally connected to either a negative pressure source or a positive pressure source, whereby the negative pressure in the web support device (90) can be adjusted to a desired magnitude. 13. The movement of a web from a vacuum transfer roll (31) or its equivalent to a press nip (N ₂ ) while being supported on only one side by a fabric (30) in a press section of a paper machine or a paper board machine. was stable in the linear transport of the web, at least one web support apparatus when placed on the support area existing between said vacuum transfer roll (31) and the press nip (N ₂₎ (60C _1, 60C ₂₎ Wherein the device comprises means for creating a negative pressure in the space (66) between the fabric (30) and the web support device (60C ₁ , 60C ₂ ) in the central area of the support distance. The web (W) and the fabric (30
) Is provided with a support roll (36) for guiding a common run, and a large roll is provided in a front edge area of the web support device between the web support devices (60C ₁ , 60C ₂ ) in the space (66). Means for generating a local negative pressure, means for generating a large local negative pressure in the rear edge area of the web supporting device (60C ₁ , 60C ₂ ) of the space (66), and Means for generating a negative pressure substantially smaller than the local negative pressure in the central area of the web supporting device (60C ₁ , 60C ₂ ). 14. The movement of a web from a vacuum transfer roll (31) or its equivalent to a press nip (N ₂ ) while being supported on one side only by a fabric (30) in a press section of a paper machine or a paper board machine. At least one web support device (60C ₃ , 60C ₄ , when stabilized in a linear transfer section of the web and arranged in a support area between the vacuum transfer roll (31) and the press nip (N ₂ ), 60C ₅ ), the device comprising means for generating a negative pressure in the space (66) between the fabric (30) and the web support device (60C ₃ , 60C ₄ , 60C ₅ ). At least two of the distance, most advantageously arranged in three web support device _{(60C 3, 60C 4, 60C} 5) is continuously, the first device of the devices (60C ₃₎ Before the edge portion is disposed a means to generate a large negative pressure in the leading edge zone of said apparatus (60C _3), the edge portion after the last device (60C _5), said apparatus (60C ₅₎ Means are provided for generating a large negative pressure in the trailing edge area, the first and last web support devices (60C ₃ , 60C ₅ ) and optionally the device between them (60C ₄ ) being the first Device (60C ₃ ) front edge and last device (
60C ₅ ) A method for producing a negative pressure substantially smaller than the large negative pressure in a part of the supporting area existing between the rear edge and the rear edge portion.