FI122893B - Friction arrangement of the forming part of the fiber web machine - Google Patents

Description

Friction arrangement of fiber forming machine forming member Gaparrangemang i formningspartiet i en fibermaskin

5 TECHNICAL FIELD

The invention relates to a friction arrangement of a forming part of a fiber web machine according to the preamble of claim 1.

10 For purposes of this application, a fiber web machine refers to paper, board, tissue and pulp drying machines.

BACKGROUND OF THE INVENTION

WO 2004/018768 discloses a two-wire former for a paper or board machine. The first wire loop passes over the first friction roll and the second wire loop passes over the second friction roll, after which the wires form a converging web. The wires merge on the surface of the dewatering gasket at the beginning of the two-wire zone. The headbox feeds a pulp suspension on the surface of an unsupported wire opposite the dewatering shoe formed by the wires. Here, the two-wire tread zone is vertical and the centers of the friction rollers are at different heights. The friction rolls in this solution consist of normal circular diameter c / j

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DE 25 41 05 215 discloses a two wire forming member in which co friction rollers are supported by hydrostatic bearings. In the first embodiment, the friction rollers overlap, so that the friction roll is horizontal. Water is supplied to the pressure chambers of the hydrostatic bearing to form a supporting surface for the chest g of the roll. A wire structure runs inside the upper friction roller to prevent the roller 30 from falling from the bearing housing in a situation where the wire does not force the upper chest roll against the bearing housing. The ends of the friction rollers have retainers which hold the friction rolls 2 in axial direction. The diameter of the friction rollers is <200 mm, whereby the headbox can be placed close to the fist and the flight distance of the headbox lip jet is short. In another embodiment, the friction rollers are side by side, whereby the friction roll is formed in a vertical plane. Such a solution is relatively complex and expensive in terms of both investment and operating costs.

EP-A-335 821 discloses a two-wire forming part in which the friction rolls are replaced by static pivoting rods. The first wire passes over the first pivot bar and the second wire passes over the second pivot bar, after which the wires form a converging web. Here, the headbox can be positioned close to the fist, leaving the headbox lip jet flight short. The problem with this solution is the high friction between the wires and the static pivoting rods. The headbox lip jet is directed to the wire between the wires after the static pivot bars. There is thus no abundance of water between the wire and the static pivoting rods, which would serve as a lubricant and reduce the friction between the wire and static pivoting rods.

The roller roller must be able to withstand high line loads due to wire tension T, typically in the order of 10 kN / m. In order for the friction roller to withstand large loads without bending, it is necessary to use a large diameter in the friction roller. The mass of the large diameter friction drum also becomes large. The frame structures of the forming member thus have to be dimensioned particularly strongly so that the rotation of the heavy friction rollers in cm does not cause vibrations in the sensitive friction area.

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uo 25 The pressures used in the headboxes also increase, which means that the headbox has to be stiffened to withstand higher pressures.

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! £> The large diameter of the friction rollers and the high pressure in the headbox lead to the co § headbox having to be located away from the hook. As a result, the free flight distance of the headlamp 30 ° lip jet increases, thus increasing the likelihood of various malfunctions in the lip jet.

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SUMMARY OF THE INVENTION

The frictional shielding of the fiber web forming machine according to the invention provides an improvement over the prior art solutions. The free flight distance of the headbox lip jet is short and the friction on the wires in the kid is low.

The main defining features of the fiber forming machine according to the invention are shown in the characterizing part of claim 1.

Other features of the invention are set forth in the dependent claims.

In the solution of the invention, the at least one friction roll is a shoe roll. The outer circumference of the shoe roll consists of an elastic webbing that rotates about a static support structure, the track of which can be shaped out of the circle so that the headbox is close to the fist.

In a preferred embodiment of the invention, both friction rollers are shoe rolls.

When the sheath is formed by a shoe roller with a rotating elastic webbing, the mi-cvi is minimized by friction on the wires in the kid. The contact between the belt diaphragm and the wire remains good when the headbox mass jet is directed to the wires after the wire has detached from the surface of the belt diaper.

The lower mass of the shoe roll results in that the solution Iλ of the invention achieves a lower vibration sensitivity compared to the situation where the friction rolls co g are conventional high mass rolls. Due to the lower sensitivity to vibration, the frame structures of the forming member can be lightened in the solution of the invention.

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The solution according to the invention can also control the wire rotation, so that the so-called "kt" rolls in the middle of the fault cycle are no longer needed.

The solution according to the invention can also be applied to existing forming parts, whereby conventional friction rollers of the forming part are replaced with shoe rolls.

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

10 BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 is a schematic view of a forming part of a fiber web machine in which the friction arrangement according to the invention can be applied.

Figure 2 is a diagrammatic view of a kite arrangement according to the invention.

Figure 3 illustrates a variation of the kite arrangement according to the invention.

Fig. 4 shows another variation of the guitar arrangement according to the invention.

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DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. 1 is a schematic side view of a forming section of a fiber web machine in which the friction arrangement according to the invention can be applied. The forming section comprises a first wire loop 11 rotating a first g roll roll 100 and a second wire loop 21 rotating a second roll roll 200.

The direction of travel of the first wire 11 is indicated by the arrow SI and the second wire 21

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g is indicated by arrow S2. After the first friction roll 100, the first wire 11 and the second wire 21 form a converging web G, at the end of which the wires 11, 21 merge and form an upwardly directed double-wire zone. The headbox 40 feeds a pulp suspension jet to the gap G between the wires 11, 21. After the junction, the wires 11, 21 pass over the first curved dewatering zone Z1. The first curved dewatering zone Z1 consists of a curved water-5 discharge shoe 50 disposed inside the first wire loop 11. After the first curved dewatering zone Z1, the wires 11, 21 pass over the second curved dewatering zone Z2. The curvature of the second dewatering zone Z2 is opposite to that of the first curved dewatering zone Z1. The second curved dewatering zone Z2 consists of a dewatering unit 60 within the second wire loop 21. The dewatering unit 60 has two successive suction chambers. The first suction chamber in the direction of travel of the wires 11, 21 comprises a strip cover placed against the inner surface of the second wire 21. On the opposite side of the strip cover, inside the first wire loop 11 is a loading strip unit 61. The second suction chamber comprises a second strip sheet facing the inner surface of the wire 21. Further dewatering means, such as suction boxes on either side of the wires 11, 21, as shown in the figure by dashed lines, may still be provided in the two-wire-15 zone.

After the second dewatering zone Z2, the wires 11, 21 pass over the third dewatering zone Z3. The third dewatering zone Z3 consists of a suction roll 13 arranged inside the first wire loop 11, the wires 11, 21 of which pass through the sheath in a defined sector. This is followed by a slightly downwardly directed cm twin section, at the end of which the second wire 21 is separated from the first wire.

cm of wire 11 on a guide roll 23 and is guided to the return cycle. Thereafter, the web W

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cp 25 extends obliquely downward on the upper surface of the first fabric 11 to the pick-up position P, o co where the web W is moved from the first fabric 11 to the lower surface of the press section pickup fabric £ 31 by means of a pick-up suction strip inside the pickup fabric loop 31 . In the support of the lower surface of the pick-up fabric 31, the web W is further guided to the press section.

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Fig. 2 is a diagrammatic view of a chain system according to the invention in which the friction rollers 100, 200 are shoe rolls. Each shoe roll 100, 200 comprises a stationary support beam 110, 210, which is rotated around an elastic webbing belt 120, 220. The webbing 120, 220 is water-impermeable to prevent fibers, fillers or fines from entering the shoe 5 roll 100, 200. The supporting beam 110, 210 is supported at its ends by the frame structures of the forming member. The support beam 110, 210, in turn, is supported by a shoe-forming shoe 130, 230 and guide members 140, 240. The rotational circumference of the belt diaper 120, 220 is thus formed by a circuit formed by the shoe 130, 230 and the guide members 140, 240. The first wire 10 passes in a predetermined sector on the outer surface of the belt diaper 120 of the first friction roll 100 and the second wire 21 passes on the outer surface of the belt diaper 220 of the second friction roll 200. The belt diapers 120, 220 of the friction rollers 100, 200 thus rotate with the wires 11, 21. The direction of rotation of the belt diapers 120, 220 is indicated by arrows S3 and S4. The design of the shoes 130, 230 and the guide members 140, 240 15 suitably provides a situation in which the belt diaper 110, 210 does not rotate along a circular path but on an egg-shaped path. Such a k i ck system 11 provides additional space for the head box 40, whereby the head box 40 can be placed closer to the gauge G formed by the wires 11,21, as compared to the conventional k ride roll system.

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The radius of curvature R1 of the curved guide surface defined by the shoe 130, 230 is smaller than the mean radius of curvature R of the shoe roll 100, 200 The average radius of curvature R of the shoe roll 100,200c is formed by a circular portion R of the opposite portion of the shoe roll 100,200.

The shoe roll 100, 200 further comprises injection devices 150, 250 for injecting g of lubricant per inner surface of the belt diaper 120, 220. The lubricant passes along the inner surface of the belt sleeve 120, 220 and forms a lubricant film on the belt

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g pan 120, 220 between the inner surface and the support surface of the shoes 130, 230 and the support surface 140 of the support members 140, 240 g. For example, water or oil can be used as a lubricant.

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The shoe roll also comprises means for tightening the belt diaper 120, 220 (not shown). Hereby, for example, the support members 140, 240 and / or the shoe 130, 230 can move in the radial direction, whereby the belt sheath 120, 220 can be tightened to the desired shape. In addition, shoe 130, 230 may be profiled in shape, whereby it may spread web 11,21.

The pulp suspension jet fed by the headbox 40 hits the wires 11, 21 after the wires 11,21 have been detached from the outer surface of the shoe rolls 100, 200 belt diapers 120, 220. The impact of the pulp suspension jet is thus on a plurality of wires 11, 10 21. The wires 11, 21 are detached from the outer surface of the belt diaper 120, 220 preferably within the curved guide surface of the shoe 130, 230.

Figure 3 illustrates a variation of the kite arrangement according to the invention. In this embodiment, the centers of rotation C1, C2 of the belt rollers 100, 200 of belt rolls 100, 200 are located in the same horizontal straight line L1. The shoe 130 of the first kit roll 100 is located vertically below said line L1 and the shoe 230 of the second kit roll 200 is located vertically above said line L1. In this embodiment, the dewatering shoe 50 following the friction G is located within the second wire loop 21. The dewatering unit 20 60 following the dewatering shoe 50 is in turn located within the first wire loop 11 and the loading unit 61 acting against it is located within the second wire loop 21. In this embodiment, the lip jet of the headbox 40 is directed to the outer surface c1 of the first wire 11 just before the wire 11,21 overlaps the outer surface of the dewatering shoe 50. The lip spray of the headbox 40 is directed to the outer surface of the wire 11 after the wire 11 has been detached from the surface of the belt diaper 120 of the first roller 100 in the area of the shoe 130.

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Fig. 4 shows another variation of the kite rigging according to the invention.

This embodiment corresponds to the embodiment shown in Fig. 3 with the difference that the rotational centers C1, C2 of the first and second pulleys 100, 200 are rotated at a different height in the vertical plane. The center of rotation C1 of the belt 100 of the first roller 100 is located at a distance D higher than the center of rotation C2 of the belt 200 of the second roller 200.

Existing 10 m wide dieformers use friction rollers with a hal-5 clearance of about 1000 mm. The free flight distance of the lip jet from the headbox is then approximately 300 mm. By using shoe rollers as stomping pads, this free flight can at best be halved. The outer circumference of the shoe roll webbing may be shaped such that the outer periphery forms a circumferential sector of circumference of about 20 to 250 mm, about 30 to 80 degrees, with substantially straight peripheral portions starting at both edges, joining about 600 to 1000 mm in diameter. with a circular circumference. The small turning radius of the shoe roll shoe and the straight sections that follow make it possible to position the headbox very close to the fist. The radius of curvature of the strap roll belt is smaller in the shoe region than the average radius of curvature of the roll roll 15.

In the embodiments shown in the figures, both friction rollers consist of shoe rolls. This is a cheap solution, but the Idta arrangement can also be implemented so that only one friction roll is a shoe roll and the other friction roll is a conventional roll. 20 With just one shoe roll, advantages over prior art solutions can be achieved.

Only some preferred embodiments of the invention are described above and it will be apparent to those skilled in the art that numerous modifications may be made thereto.

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Claims (5)

A fencing arrangement for a fiber web forming machine comprising a first wire loop (11) passing over a first wire roll (100) and a second wire loop wire (21) passing over a second wire roll (200), followed by wires (11,21). ) forming a converging cam (G) into which the headbox (40) supplies a pulp suspension jet, characterized in that at least one of the friction rolls comprises a shoe roll (100, 200) comprising a stationary support beam (110, 210) surrounded by an elastic webbing (120). 220) is arranged to rotate, which webbing (120, 10 220) is supported on a support beam (110, 210) via a shoe (130, 230) and support members (140, 240), whereby the wires (11,21) pass through a rotating webbing (110, 210). 210) on the outer surface over the curved guide surface defined by the shoe (130, 230), after which the wires (11,21) form said converging rod (G). 2. The kit of claim 1, characterized in that the two rollers consist of shoe rolls (100, 200). A barbell arrangement according to claim 1 or 2, characterized in that the radius of curvature 20 (R1) of the curved guide surface defined by the shoe (100, 200) is smaller than the mean radius of curvature (R) of the shoe roll (100,200). A barbell arrangement according to claim 2 or 3, characterized in that the wires (11, c1i21) release from the surface of the shoe rolls (100, 200) in the region of the curved guide surface defined by the shoe cv (130, 230). while 25 i co 5. A barbell arrangement according to any one of claims 2 to 4, characterized in that the wires g (11,21) coincide in the direction of travel (SI, S2) of the wires (11,21) in the region subsequent to the shoe m (130,230) below,