FI112509B - Paper machine other formers - Google Patents

Abstract

The invention concerns a gap former in a paper machine, comprising a twin-wire zone, which is composed of a first forming-wire loop (10) and of a second forming-wire loop (20) and which starts from the forming gap (G), into which the slice part (31) of the headbox (30) feeds a pulp suspension jet. The forming gap (G) is defined, from one side, by the first forming wire (10), which runs over the forming roll (11), and, from the opposite side, by the substantially straight run of the second forming wire (20) starting from the breast roll (21) to the forming roll (11). Draining equipment (40...44) is fitted inside the first forming-wire loop (10) after the forming gap (G) and the forming roll (11), which draining equipment is provided with a deflector duct (12) and with a deflector rib (12a) placed against the first forming wire (10) in the lower part of said deflector duct (12), and, inside the second wire loop (20), a forming shoe is arranged, which is provided with a ribbed deck consisting of forming ribs (22) and which is loaded against the second forming wire (20). In the invention, the first forming rib of the forming shoe or a unified forming-rib construction (22) composed of two or more forming ribs is mounted so that it can be loaded adjustably, so that the free run of the forming wires (10, 20) from the forming roll (11) to the first forming rib is substantially little.

Description

112509

A paper, a gap former Gapformare in a paper machineThe 5 The invention relates to a paper, a gap former, which comprises a first forming wire and a second forming wire consisting of twin-wire zone which begins with the forming, to which the headbox lip to make the pulp suspension, and that the forming limit from the second running over the side of the forming roll first forming wire and on the opposite side of the breast roll forming roll an outgoing substantially 10 straight run of the second forming wire, wherein, after the forming roll and forming roll, dewatering furniture provided with a deflector channel and a deflector strip facing the first forming wire is disposed within the first forming wire loop, and , 15 wherein the forming shoe The first forming strip or the integral forming strip structure composed of two or more forming strips is mounted for adjustable loading.

As paper machine speeds increase, several problems have occurred with the forming of the web; , 20 more prominently. In the forming part of the papermaking machine, the phenomena affecting the fiber network and the water that is still relatively free in connection therewith, e.g. centrifugal forces, generally increase with the square of the web speed. The maximum web speeds of some of the current paper machines are already in the order of 1500 m / min. However, machines, particularly newsprint machines, are being designed for speeds of up to about 2000 m / min 25 or even higher.

With reference to the prior art relating to the present invention, reference is made inter alia Applicant FI Patent Application No. 885609; and Valmet Ahlström Inc. Patent Applications Nos. 885606 and 885607, which disclose 30 molders marketed by the applicant under the trademark "MB-former".

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Reference is also made to Applicant FI Patent Applications Nos. 904489, 911281, 913112, 920228, 920863, 932264 and 932365, which disclose various combination configurations of the aforementioned MB-former units and hybrid and kit formers.

In the above-described dockformers, the pulp suspension is led from the headbox to a pile formed by a forming roll and two wires, whereupon both wires and the pulp layer between them follow the curvature of the forming roll, whereby most of the water is passed through the wires. The required dewatering pressure is provided by the tension of the outer wire, which creates a pressure on the pulp layer that is directly proportional to the tension of the wire 10 and inversely proportional to the radius of curvature of the forming roll. In Kida, part of the jet energy of the mass jet is converted to pressure energy and the jet speed decreases accordingly. Drainage through the outer wire away from the forming roll is enhanced by centrifugal force. Dewatering towards the forming roller can be enhanced by the vacuum of the forming roller zone.

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As the speed of paper machines increases, the amount of water discharged per unit time zone has also increased. This has made it difficult to fit overhead wire. dewatering chambers of sufficiently large cross-section within the loop, which has made it necessary to provide drainage ducts in the dewatering chambers to prevent flooding, '. 20 both on the operating and maintenance side of the machine. Treatment of side channels and other functions make it difficult. '. : are problematic because they have to be led back across the paper machine: * to the drive side, where the drainage channels are connected to the wire well.

The foregoing problems are partly exacerbated or exacerbated by the fact that there has previously been a considerable space between the beginning of the two-wire zone ': 25, e.g., the former wire guiding the former roller and the suction deflector channel at the front of the drainage chamber, where:; : a drainage chute is provided to collect and direct the water exiting the former roll to the side of the paper machine.

; While increasing the speeds of paper machines, efforts have also been made to avoid or at least reduce free strokes of the web and / or wires in order to improve the stability of the web and wires.

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However, in the current kitformer solutions, there has generally been a fairly considerable clearance between the former roll and the subsequent molding shoe, so that as the speed increases, the stability of the wires in this area could not be considered good. Current solutions have not allowed this distance to be reduced. Since the previous solutions have the following molded shoes after the for-5 marine roll mounted firmly on the former hull, the layer thickness of the pulp suspension fed from the headbox to the former must have been kept as constant and constant as possible. Therefore, the layer thickness could not be adjusted in any way. However, such a fixed strip is very suitable for use when the conditions for forming the web remain unchanged. However, the stability of the wires and the stability of the former in various driving situations have been perceived and recognized as a problem in the present structures, and in particular the present invention has sought to solve this problem.

In order to avoid the above problems and to achieve the foregoing and subsequent objects of the invention, the present invention is essentially characterized in that the free wires of the forming wires from the forming roll to the first forming die are substantially small and less than 200 mm.

The invention achieves several significant advantages over the prior art, and of these advantages, e.g. following. The main idea of the invention, that is, that the first or the first two moldings are flexibly mounted on the former, brings with it; the significant advantage that such a list can be brought very close to the former roll, even so, '; that the list is placed at the former roll itself, so there is no clearance between the former roll and the list. This substantially improves the stability of the wires and the runnability of the former 25 in various driving situations. In addition to being flexibly mounted, such a mold can be mounted in an adjustable manner, such an adjustable mold allowing runnability at a variety of basis weights, thicknesses, etc. When mounted in accordance with the invention: the mold automatically adjusts to the correct position as layer thickness changes.

: The solution according to the invention is particularly useful for different types of fine paper.

| A further important advantage is that the MB unit deflector molding in the invention can be brought along a flexible molding shoe to improve dewatering.

4 112509 In this case, the deflector strip does not need to be loaded or adjustable, but may be fixed. Other advantages and features of the invention will become apparent from the following detailed description of the invention.

In the following, the invention will be described in detail with reference to certain embodiments of the invention shown in the figures of the accompanying drawings, in which details the invention is not limited in any way.

FIG.

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Fig. 2 shows an enlarged detail of the former roll, flexible forming strip and deflector strip of the kit of Fig. 1.

Fig. 3 is a schematic sectional view showing the installation of a flexible former molding with respect to the former roll 15.

The former shown in Figure 1 is a so-called. a dieformer, in which the lip 31 of the headbox 30 feeds the forming spool G between the pulp suspension jet forming wires 10,20. The geometry of said forming ridge G is determined from above by the forming roll II and below the chest roll 21 21 which controls the forming wire 20. Top wire mesh; that is, within the first forming wire loop 10, after the forming roll 11, the MB unit 40 follows. For fine adjustment of the kit geometry of the forming gate G, the breast roll 21 is tracked. to be adjustable in position in the direction of arrow E, ie one exemplary embodiment mainly in the vertical direction of Fig. The geometry of the forming web G is preferably such that the forming web 10,20 has a curved sector common to the forming roll 11 The first forming web 10 is formed into a wire loop by the forming roll 11 and lead rolls 14 and as above. already stated, the MB-unit 40 is mapped within said first forming wire loop 10. In the embodiment of Figure 1, the MB unit 40 comprises two; dewatering chamber 41.42, which has been followed by a vacuum. Each of the: 30 dewatering chambers 41,42 is provided with a dewatering channel 43,44 through which the water led to the dewatering chamber 41,42 is discharged from the dewatering chamber by means of said vacuum. In each of the dewatering chambers 41.42, water enters via a deflector passage 12.13. As shown in connection with the first deflector channel 12, at the lower end of the deflector channel 12 is located a deflector strip 12a against the first forming wire 10. The deflector strip 12a thus restricts said deflector channel 12 and guided by the deflector strip 12a 5

Correspondingly, the second forming wire 20 is formed as a wire loop by means of the breast roll 21 and the guide rolls 21a. Inside the second wire loop 20, after the forming curve G and the common curved sector a of the wires 10, is formed a first forming shoe 22 for the forming shoe against the second forming wire 20, followed by a plurality of spaced apart forming strips 23 arranged as a strip. The mold or similar mold cover is integrated into a common box 24, whereupon, if necessary, a vacuum can be introduced to enhance dewatering through the second forming wire 20. The first mold or similar mold cover, as shown in Figure 1, is substantially straight or slightly curved. After the first mold 23, a second mold 25 or the like mold cover is provided inside the second forming wire loop 20 and is similarly integrated into the box 26.

The open strip cover of the working strip 25 is formed as curved, as shown in Fig. 1, so that this curvature results in compression between the wires 10,20. a running pulp web, whereby this compression together with the curvature of the strip cover 25; Due to the centrifugal force obtained by '·', water is removed from the pulp web through the first forming wire 10. This discharged water is led through a second deflector channel 13 "rt '' 25 to a second dewatering chamber 42, preferably assisted by a reduced pressure.

, ((Dewatering is further enhanced and promoted at the bottom of the second deflector channel 13; the 'deflector strip (not shown). Further formed within the second forming wire loop 20': a plurality of suction boxes 27 with a lid to provide water exit from the pulp web through the second forming wire that the pulp web 30 follows along the second forming wire 20 as the strands of the wires 10.20 are separated from each other .After the suction boxes 27 is followed by a second forming roll 28 provided with 6 112509 suction zones 29 to further drain water from the pulp web and ensure that the pulp web it is shown that a suction box 27a is further frozen inside the second forming wire loop 20, after which the run of the second forming wire loop 20 and the resulting paper web W are guided to a 5 pick-up (not shown) from which the paper web W is taken an press section.

Fig. 2 shows an enlarged detail of the area of the former forming gate G of Fig. 1 and of the first forming mold or similar mold structure. According to Figure 2, the first forming strip structure 22 comprises two successive forming strips 10 22a, 22b interconnected by means of a fastening means 22c or the like. This forming strip structure 22 is supported on the body 22d of the former or box 24 by adjustable loading members, preferably by loading hoses 22e such that the desired supply of pressure medium to these loading hoses 22e causes the strip structure 22 to position in the desired position with the wires 10.20 and forming roll 11. When pressurized air 15 is used as the pressure medium 15, the forming strip structure 22 is flexible in configuration, whereby the strips 22a, 22b are automatically positioned correctly if, for example, the layer thickness of the pulp suspension to be applied to the forming foil G changes. The pressure of the pressure medium in the loading hoses 22e can be adjusted even while driving. In addition to adjusting the pressure of the strips against the second forming wire 20, the loading hoses * 22e can also be used to adjust the angle of the forming wire 20 • »· with the said loading hoses 22e, 22b. ·. : regarding.

: '·; Even more important than the flexible installation method or the possibility of adjusting the runners 22a, 22b is that the construction according to the invention allows the first: *: 25 forming strips 22a, 22b to be brought substantially closer to the forming roll 11 than before, between the forming roll Ily and the first forming strip 22a; Y: There is no clearance at all. This has been particularly illustrated in Figure 3,. wherein conventional structures always have a free distance α between the forming roll (marked with a dotted line) 11 'and the first forming strip 22a, which has generally been in the order of 200 mm or more. As further shown in Fig. 3, the forming strip 22a according to the invention can be brought just above the forming roll 11, whereby this free distance a is not at all. This clearance clearance substantially improves the stability of the wires 10,20 and the runnability of the former in various driving conditions. The invention has free run from forming roll 11 to first forming strip 22a preferably between 0 and 70 mm.

Such an adjustable, flexible or inflexible installation is particularly advantageous for fine paper grades, whereby the common bending sector a of the wires 10,20 is very small and the pulp age is more common than when using a larger bending sector cl. 10 may be pulled from the forming wire 20 at start-up and when the machine is lowered. Also, when necessary, the strip may be pulled out of the wire 20. The structure may have fixed stops for these adjustable moldings against which the mold is loaded during driving. fixed position. In such a case, a hydraulic pressure medium may be used as the pressure medium and the pressure supply 15 to the loading lines 22e may also be handled manually.

The invention has been described above by way of example with reference to the figures in the accompanying drawings. However, the invention is not limited to those shown in the figures; · (Embodiments, but the invention can be modified within the scope of the inventive idea defined in the appended claims. · Thus, although the examples shown in the drawings. ':: Are so-called "horizontal formers", the invention is equally applicable to vertical crystal transformers and the like.

Claims (11)

A gap molding in a paper machine comprising a dual wire zone consisting of a first forming wire loop (10) and a second forming wire loop (20), which zone bends from a forming gap (G) to which the lip opening (31) of the inlet carriage ( 30) feeds a pulp suspension beam and which forming gap (G) on one side is limited by a first forming wire (10) running over a forming roller (11) and on the opposite side a substantially straight course of a second forming wire (20) which likes from a breast roll (21) for the forming roller (11), after which the draining gap (G) and the forming roller (11) 10 are arranged within the first forming wire coil (10) dewatering equipment (40-44), which is provided with a deflector channel (12) and a deflector strip ( 12a) in its lower part against the first forming wire (10) and inside the second wire loop (20), a forming shoe is provided with molding lid consisting of molding strips (22,22a, 22b), which shoe is loaded against it. the second molding wire (20), wherein the first molding strip (22a) of molding shoe or the uniform molding structure (22) composed of two or more molding strips (22a, 22b) is mounted to be controllably loaded, characterized in that the of the forming wires (10.20) from •. : the forming roll (11) of the first molding strip (22a) is substantially smaller and smaller than. '.'. 200 mm. : Y: 20 Gap former according to claim 1, characterized in that the first molding strip (22a) or a corresponding molding strip structure (22) is mounted so that it can be controllably loaded in such a manner that said molding strip (22a) or molding strip construction can be detached from the second the forming wire (20). ; : 25 Gap former according to claim 1 or 2, characterized in that the first: forming strip (22a) is mounted substantially in the running direction of the forming wires (10, 20). * at a location where the forming wires (10, 20) leave the forming roll (11) at the end of them; common bending sector (a). : 30 12 112509 Gap former according to claim 1 or 2, characterized in that the first forming strip (22) or a corresponding forming strip structure (22) is mounted substantially at the deflector strip (12a) which is inserted immediately after the forming roll (11). Gap former according to any of the preceding claims, characterized in that the first forming strip (22a) or the corresponding forming strip structure (22) is loaded against the second forming wire (20) with pressure means driven by pressure medium, such as load hoses (22e) or the like. 6. Gap former according to claim 5, characterized in that the first forming strip (22a) or the corresponding forming strip structure (22) can be loaded in a controllable manner with hydraulic pressure medium at least to the driving position and free position. Gap former according to claim 5 or 6, characterized in that the first molding strip (22a) or the corresponding molding structure (22) can be loaded with hydraulic pressure medium to the desired position between driving position and free position. Gap former according to claim 5, characterized in that the first; 1, ·. the molding strip (22a) or the corresponding molding molding (22) is flexibly loaded. V; 20 with pneumatic pressure medium. I 4 • t »• i Gap former according to claim 8, characterized in that the first molding strip (22a) or the corresponding molding structure (22) is loaded pneumatically in such a way that the molding strip (22a) or the corresponding molding structure (22) is automatically arranged to adjust according to the layer thickness of the fiber mass. Gap former according to any of the preceding claims, characterized in that the course of the forming wires (10, 20) of the forming roller (11) to the first forming strip 30 (22a) is substantially noil. 13 112509 11. Gap former according to claims 1-9, characterized in that the inlet of the forming wires (10, 20) from the forming roller (11) to the first forming strip (22a) is in the range 0-70 mm. 5 f '»