FI118773B - Press section for a sheet forming machine - Google Patents

Description

118773

CLAMBER COMPONENT OF BREAKING MACHINE

The present invention relates to a press section of a forming machine for increasing the dry solids content of a web being manufactured by a forming machine, comprising substantially at least three separate press nipples, wherein - the first press nip having first and second press webs between which the web is disposed. via a first press nip to drain water through both surfaces of the web, - the second and third press nip having third and fourth press webs for conveying the web through said press nips and for dewatering to a third and fourth press nip, and - a second and third press nip having a transfer belt arrangement. , disposed on a different side of the web than the third and fourth press fabrics.

20 U.S. Patent No. 5,833,810 discloses a press portion of a paper machine for secure web transfer and effective dual. , for half dewatering. Dewatering is achieved by using a plurality of successive press nipples. In addition, the press portion utilizes a transfer belt guided through the press nipples, which provides a so-called "closed" export. In other words, the web t · · j ··· is transported, supported by a transfer belt, from one press nipple • · ·: ·· · to another, thus avoiding web transfers over open gaps.

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Despite the duplex dewatering, the pressed • • • · ϊ ** 30 tin forms a web with different surfaces. In practice, the other surface of the web is substantially flatter than the other surface, as it passes through a plurality of press nipples *: * ·· supported by a transfer belt. In addition, the web is structurally asymmetric and:.

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It is an object of the invention to provide a novel press section of a forming machine which provides not only efficient and symmetrical dewatering, in particular a symmetrical and smooth web with a surface quality and density distribution. Characteristic features of the present invention will be apparent from the appended claims. According to the invention, both surfaces of the web are pressed against a smooth contact surface 5. Hereby a substantially uniform surface is obtained on both sides of the web. Similarly, homogeneity of the web is ensured by duplex dewatering. By arranging both the dewatering and the pressing against the smooth surface, a substantially symmetrical web of favorable construction is obtained. In addition, the pressing action can be adjusted by selecting different components in the press section. Also, the transfer of the web to the production part following the press section can be ensured in various ways.

The invention will now be described in detail with reference to the accompanying drawings, in which:

Figure 1 shows a first embodiment of a press section according to the invention,

Fig. 2 shows a second embodiment of a press section according to the invention, Fig. 3 shows a third embodiment of a press section according to the invention. application, • · e ·· ·. Fig. 4 shows a fourth embodiment of a press section according to the invention, e · I. *, Fig. 5 shows a fifth embodiment of a press section according to the invention.

Fig. 6 shows a sixth embodiment of a press section according to the invention.

Figures 1-6 show various applications according to the invention. Most of the disclosed features of the invention may occur in different applications independently of each other, which increases the number of variations. Despite the variations, the applications include ·· «a common basic solution to achieve the objectives of the invention.

3, 118773

Other additional solutions may further adjust the operation of the press member, for example due to the raw material or available components. Additional solutions can also influence the behavior of the web on a web forming machine and above all affect the quality of the end product.

The press section of the forming machine is intended to increase the dry solids content of the forming film. In practice, essentially 10 water is discharged from the web when pressed. For current web forming machines, the design speed is up to 2000 - 2400 m / s. In this case, a substantially closed export must be used to control the wet web on the press section. In other words, the web is supported as well as possible along the entire press section without the so-called clearances. The most common 15 forming machines are paper or board machines.

Each press member shown in the figures includes at least three separate press nips 10, 11 and 12. The number of press nips maximizes the amount of water leaving, thereby increasing the dry solids content of the web at the end of the press member. At the same time, the selection and adjustment of press nipples can influence the function of the press • • and the quality of the end product. For the first press nip • ·:, · | 10 is provided with first and second press fabrics 13 and 14 between which the web is arranged to pass a first press; 25 through tinnip 10. This arrangement removes water · «· ·; ; * · Through both surfaces of the web. Similarly, the second and third • · · ·. ···. the press nip 11 and 12 have a third and a fourth press fabric 15 and 16 for conveying the web of said press nipples. . 11 and 12. Here, the press fabric is only on one side of the web, but the press fabric supports the web while removing water through one surface of the web at a time. In addition, a second and a third press nip 11 and 12 have a transfer belt an arrangement 17 disposed on the other side of the web than the third and • · · fourth press fabrics 15 and 16. The web is supported on both the 35 third and fourth press fabrics as well as the transfer belt arrangements when passing the second and third press nipples. through.

According to the invention, the transfer belt arrangement 17 comprises two transfer belts 18 and 19. In this case, advantageously short transfer belts can be used and simple belt turns can be used to support them. It is also possible to handle separate transfer belts, such as individual heating, for example, which facilitates control of the press section. Further, according to the invention 10, the transfer belts are arranged to contact different surfaces of the web. In other words, the web is pressed on both surfaces against a smooth counter surface. In this case, the press section already provides smooth top and bottom surfaces to the web, which, after calendering and possible coating, also results in a good surface quality in the final product. For example, the paper formed with such a press tin is well suited for printing. Especially in gravure printing, the printing is excellent without missing dots. In addition, the asymmetric dewatering and sealing of the web with its top and bottom surfaces in approximately the same manner against a smooth surface further provides the web with as symmetric density distribution as possible. This • · * feature is also advantageous for printing paper, with the absorption of oil and ink • ♦ · being similar across printing paper and · * · on both sides. In addition, the roughness profiles of the web surfaces and: the transverse humidity profiles are smooth and additionally lal · • symmetric on different web surfaces.

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When the transfer belts are separate, suitable means are used. . for transferring the web from the first conveyor belt 18 to the second conveyor belt 19. In the embodiments shown, the press member * · "·" includes a transfer fabric 20 fitted to both conveyor belts. both surfaces alternately in contact with a smooth transfer belt, so that the * ··. *, lower and upper surfaces smooth and seal as closely as possible · In practice, the third press fabric adjacent to the second * · ·· * press nip provided before the transfer fabric is 118773 with a different surface of the web than the fourth press fabric which is part of the third press nip provided after the transfer fabric, in which case the water is also alternately discharged through the different surfaces of the web, which improves and unifies the web.

5 As the press nip presses one surface of the web against the smooth transfer belt, water is also discharged into the press fabric through the other surface.

The web is guided to the press section by a preceding web forming section, of which only a portion of the wire 21 is shown here. From the wire 21, the web is transferred to the first press fabric 13 by a so-called pick-up roll 22. The web proceeds between the first and second press fabrics the press fabric 13 also has 15 transfer suction rolls 23 which ensure that the web stays with said press fabric up to the so-called center roll which is counter roll 24 in the second press nip 11. In the second press nip 11 the web is pressed between the third press fabric 15 and the first conveyor belt 20 through to the fourth press fabric 16. In the second press nipple 11 smooth • ·:! : against the transfer belt 18 is the lower surface of the web and, respectively, in the third press nip 12, the upper surface of the web is smoothed. According to the invention: ***: the transfer belts 18 and 19 are preferably arranged in the counter rolls 24 and • ···· * of the second and ··· 25 third press nipples 11 and 12. 25 to the side of the web. In other words, the transfer belts are well supported • «i *. ···. against the counter roll, which ensures smooth transfer belts.

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After the third press nip 12, the web is moved to the press member. . for the next production part, which is mainly shown here

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The drying fabric 26 and the first drying cylinder 27. The web may be transferred to the dryer fabric in various ways, which will be explained in more detail later, e.

The press section uses press felts as press fabrics to remove water from the web. The transfer belts are almost • · ** ·· 'air and water impermeable, but can also be 6,118,773 partially water permeable and even dewatering. The press section according to the invention further utilizes conveyor belts with as smooth a surface as possible. The surface roughness Ra of the transfer belts is about 0 / 5-4 µm, more preferably 0.7-2 µm, etc. A transfer wire is preferably used as the transfer web, although a felt fabric may be used. The transfer felt avoids the marking of the web, which contributes to a smooth surface. On the other hand, it is more difficult to extend the vacuum effect through the transfer felt to the web than with the transfer wire. Figures 1-6 further show conventional felt refining devices, such as felt vacuums and lubricating and washing showers.

The basic arrangement of the invention described above provides an effective dewatering through both surfaces of the web, smoothing of both surfaces, and sealed export. The press section can be varied and adjusted by changing and / or adding components. Hereby, each press section is provided with a reliable operation regardless of the web quality and the final product is formed of high quality. The first press nipple 10 may be a roll nip (Fig. 3) or a long nip which provides effective drainage without the breaking of the web, i.e. without so-called curling. In addition, the position of the rolls forming the ***; Symmetric water I · »ί · *. 25 removal can be ensured by fitting the first press nipple · ·: ·. 10 for the substantially straight portion of the first and second press fabrics 13 and 14. Like the first press nip, the third press nip 12 may be a roll nip or a long nip but a second. , the press nip 11 is preferably always a long nip. In addition, the long strap lengths are favorable for vibration despite the high load capacity.

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Also, a transfer suction roll 23 adapted to support the first press fabric 13 described above may be disposed in various ways. In the figure # · ♦ * · '·' 35, the transfer suction roll 23 is arranged to form a nip with a return roll 24 belonging to the second ··· * * press nip 11. On the other hand, the 7 118773 may be in nip contact with the nip roll 28 of the press member (Fig. 2) or even both (Fig. 5). Further, even the counter roll of the first press nip can be arranged to form a nip with the center roll (Fig. 6). This reduces the 5 press parts and reduces the required components.

Figures 1 to 5 further show a steam box 30 provided in connection with the transfer suction roll 23 through which a steam jet is applied to the web. Heating the web improves the drainage of water due to a decrease in viscosity at the next nip and ensures that the web is transferred to the center roll transfer belt. Also, in connection with the transfer fabric 20, it is advantageous to provide a steam box 31 which is here aligned with the web before the second transfer belt 19. Similarly, before the first press nip 10, the press section 15 includes a steam box 29. With the press section, the steam boxes are located and used. Instead of the steam box 31, an infrared heater can also be used, which is advantageously adjusted in the transverse direction of the machine, so that the moisture profile of the web can be straightened. In addition to the heating means, it is also possible to adjust the moisture profile by wetting the web in a profiled manner.

• * • # * · Generally, the introduction of heat into the web contributes to increasing the dry matter content. The same means may also be used on the transfer belts «» · ej * "* j. Heating of the transfer belt also improves the quality of the surface of the web · * φ:. *. 25 According to the invention, the first and / or second heating means • e · 32, 33 before the second or third press nip 11, 12 are provided. Body • 32 and 33 are shown in Fig. 5, which shows 4, a steam box combined with a condenser scraper. Instead of the steam box • · · ·· * * 30, the heating means may consist of, for example, an infrared heater or a hot air fan. The heating means 32 and 33 · * · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · In addition also • " .·**. the profiler devices can be connected to the blowing devices as needed, which may be heating or humidifying means. In Figure 5, the devices 42 are * ... * arranged after the horizontal portion 37 and the other devices 43 8 118773 respectively between the vertical portions. Moreover, said means to correct the curl of selecting a heating or humidifying suitably different sides of the web, in other words, with respect to the heating cylinder drying of the web 5 through the opposite surface or the wetting on the same side as the cylinder drying. Equipment shall be located and used as required.

According to the invention, means 10 are provided in connection with the second transfer belt 19 for transferring the web from the press section to a drying wire 26 belonging to the subsequent drying section (Figure 4). Thereby, the web can be moved in a controlled manner between the production parts and the press member can be fitted to various web forming machines. In Figure 2, the means 34 include a second transfer fabric 35 for transferring the web from the second transfer belt 19 to the drying wire 26. The web from just the third press nip may still be so wet that a reduced temperature must be applied to the first drying cylinder. In addition, the wet and elastic web tends to follow 20 drying rollers, preferably smooth, rather than the drying wire, for example due to the vacuum of the opening kid and the web may · ·: be interrupted by the speed difference between the production parts.

The above problems can be avoided by using a blower dryer 36. The blower dryer includes a web-supporting track arrangement and a blower chamber with ·· ·. * ··. at the surface, a perforation to distribute hot air or other hot gas to both the blowing surface and the surface of the web. Humid air . is removed through the other holes in the blowing surface. The blower dryer • · * 30 can also be used with a press section other than the above. According to the invention, the blowing dryer 36 includes a horizontal portion 37 or a horizontal portion and: *** a vertical portion 38. For example, in Fig. 3, the inflating dryer 36 has only a horizontal portion 37, whereas in Fig. »I, * 35 horizontal portion 37 and vertical portion 38. Functionally •» **** like parts have been used with the same reference numerals.

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All of the above press members may also use a vacuum dryer 39 fitted against a pick-up roll 22, though only shown in Figure 2. In practice, the nip rolls inside the transfer belt loops may be either smooth or onsip-5. If the transfer belts are partially water permeable, it is preferable to use on-surface nip rolls. The discharged water is then pressed into the surface pattern of the nip roll and thence further splashed into the drainage tray (not shown). The actual dewatering takes place in high load slip shoes based on 10 long nip or high load roll nipples. The long nipple clamp is also called the shoe press. Depending on the loads used, so-called transfer nipples may also contribute to dewatering and / or modification of the web structure. The transfer nipples are referred to in the figures as 40 and 41. In the long nip 15, the loading range is preferably about 500 to 1500 kN / m, while in the telecommunication nip the load range is 80 to 250 kN / m. Correspondingly, in the transfer nipples, the loading range is 30 - 100 kN / m. In Fig. 6, the first press nip includes a suction roll which, in order to ensure durability, uses a shoe press 20 in this application in a loading range of 100 to 400 kN / m.

• 9 9 9 9 9 9 9 "1.1 The press section of the invention can be modified in a number of different ways. T. *" 1. However, to achieve a high quality end product, "· symmetrical dewatering and pressing of both sides of the web are essential. This is achieved by a conveyor belt arrangement according to the invention, the operation of which may additionally be adjusted and enhanced in various ways.

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Claims (16)

1. The pressing portion of the sheet forming machine, which is intended to substantially increase as a closed transmission the dry matter content of a web produced with the sheet forming machine, and the pressing portion comprising at least two separate press nips (11, 12), in which - in connection with the first and the second press nip (11, 12) provides a first and second press tissue (15, 16) for transit) port of the web via the said press nip (11, 12) and for removing water to the first and second press fabrics (15, 16), and - in conjunction with the first and second press nip (11, 12), there is a conveyor belt arrangement (17) arranged on the other side of the web than the first and second press fabrics (15, 16), which conveyor belt arrangement (17) comprises two conveyor belts (18, 19) which are arranged to touch the different surfaces of the web, and the pressing portion comprises one. . conveying tissue (20) for conveying the web from the first conveyor belt (18) to the second conveyor belt (19), characterized in that the pressing portion comprises a third press nip * ·] ··· * (10), which is arranged prior to the first press nip (11) and · · · · in connection with which there is a third and fourth press nip (13, 14) between which the web has been arranged to run via the third press nip (10) for removing water through the bed surfaces of the web, and the first press nip (11) is a ··: * · * long nip. ·· • · • · • ·· 1 2 j * · Press section according to claim 1, characterized in that the first and second press nip (11, 12) comprise support rollers (24, 2, 25), on which side of the web the conveyor belts (18, 19) have • * ♦ · * provided. • · ♦ «· • φ Press section according to claim 1, characterized in that a first press tissue (15) existing prior to the transport tissue (20) arranged in connection with the first press nip (11) is in contact with the second of the web's surfaces than the second press woven (16). , which is associated with the second press nip (12) arranged after the transport tissue (20). 4. Pressing portion according to any of claims 1-3, characterized in that the third press nip (10) is a roll nip or a long nip. Pressing portion according to any of claims 1-4, characterized in that the third pressing portion (10) is arranged on the substantially straight portion of the third and fourth press waveguides (13, 14). Pressing portion according to any of claims 1-5, characterized in that the second press nip (12) is a roll nip or a long nip. Press section according to any of claims 1-6, characterized in that the press section comprises a transport suction roll (23). : 20 arranged to support the third press fabric (10) of the third press nip (10). 8. Press section according to claim 7, characterized in that the conveyor suction roller (23) is arranged to form a nip (40, 41) together with it. support roll (24) included in the first press nip (11) and / or together with the nip roll (28) contained in the press portion. • · · · Press section according to claim 7 or 8, characterized in that it is arranged in connection with the transport suction roll (23) • ♦ an angled cover (30) which has aimed at the track. • 1 2 · • ·· • · · • · 2 Press section according to any one of claims 1-9, characterized in that an angel skin (31) has been arranged adjacent to the transport tissue (20), which is directed towards the web before the second conveyor belt (19). 118773 Press section according to any one of claims 1 to 10, characterized in that heating devices (32, 33) have been arranged in connection with the first and / or second conveyor belt (18, 19) before the first or second press nip (11, 12). 5 Press section according to claim 11, characterized in that the heating devices (32, 33) consist of an infrared heater, a hot air fan or a meadow. Press section according to any one of claims 1 to 12, characterized in that it comprises an angel cover (29) before the third press nip (10) in the press section. Press section according to any one of claims 1 to 13, characterized in that devices (34) are arranged in connection with the second conveyor belt (19) for conveying the web from the press section to a drying wire (26) which is included in the following drying portion. • t · 20 Press section according to claim 14, characterized in that the devices (34) comprise a second transport tissue (35) ··· ϊ, or a blow dryer (36). • · ♦ · # • · · • · · ·! # Ί1ί Press section according to claim 15, characterized in that the blow-drying dryer (36) comprises a horizontal part (37) or a horizontal part and a vertical part (38). • · • · · · M · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · f • ·