WO2006106178A1

WO2006106178A1 - Method and device for changing a fabric in a paper or board machine

Info

Publication number: WO2006106178A1
Application number: PCT/FI2006/050121
Authority: WO
Inventors: Veli-Matti Vainio; Martti Salminen; Samppa J. Salminen; Jyrki Savela
Original assignee: Metso Paper Oy
Current assignee: Valmet Technologies Oy
Priority date: 2005-04-05
Filing date: 2006-04-03
Publication date: 2006-10-12
Anticipated expiration: 2007-10-05
Also published as: FI117397B; CN101155960B; EP1866479A1; FI20055152A0; CN101155960A; EP1866479A4; US7900330B2; EP1866479B1; US20080209706A1

Abstract

The device comprises two units placed one on top of the other, each unit comprising a first side frame (101), a second side frame (102) spaced from the first side frame, and a band (130) running between the side frames (101, 102). Each unit (100, 200) additionally comprises a pressure chamber (300) attached to the side frames (101, 102) and positioned in a sealed manner against the inner surface of the band (130).

Description

Method and device for changing a fabric in a paper or board machine

TECHNICAL FIELD

The invention relates to a method defined in the preamble of claim 1.

The invention also relates to a device defined in the preamble of claim 4.

BACKGROUND ART

FI patent 103421 discloses a method and a device for changing a fabric in a paper machine. In the method, frame beams of the tending side are moved to a position in which a gap is formed in the vertical frame beams and the fabric is changed through said gap. In the method, the frame parts of the frame beam are raised by an actuator onto support of a device comprising a set of rollers and the fabric is passed through the gap into a throat of the set of rollers. The set of rollers serves as a fabric-pulling device during the change process and after the change the vertical frame beams are lowered onto backing surfaces of the frame parts.

This kind of device formed of a set of rollers comprises a very large number of separate parts, even thousands of parts. The assembly of the device is time- consuming, maintenance is expensive, and the large number of parts additionally reduces the reliability of operation of the device.

The arrangement in accordance with the invention aims to reduce problems associated with the arrangements of the state of the art. SUMMARY OF INVENTION

The method according to the invention is mainly characterised by what is stated in the characterising part of claim 1.

The device according to the invention is mainly characterised by what is stated in the characterising part of claim 4.

The device according to the invention includes a very small number of separate parts, a few tens of parts. The device is therefore easy to assemble, inexpensive to maintain and its reliability in operation is good.

A pressure medium between a pressure chamber and a band of the device applies a very even pressure to a fabric passing between bands. The caterpillar track of the set of rollers in accordance with the state of the art is formed of a large number of short pieces, so that a small gap remains between the pieces where pressure on the fabric between the caterpillar tracks is zero. Thus, caterpillar tracks cause an uneven pressure on the fabric passing between the caterpillar tracks.

The definition "paper or board machine" includes in this application all machines and devices that are associated with the manufacture of paper and board and have changeable fabrics, such as paper machines, board machines, tissue machines, pulp machines and belt calenders.

BRIEF DESCRIPTION OF FIGURES

In the following, the invention will be described in detail with reference to the exemplifying embodiments shown in the figures of the appended drawing, to the details of which embodiments the invention is not meant to be limited. Figure 1 is a sectional view of frame structures of a press section when viewed in the machine direction.

Figure 2 is an axonometric view of the device in accordance with the invention for changing a fabric.

Figure 3 is an axonometric view of one unit of the device in accordance with the invention.

Figure 4 is an axonometric view of a variant of the device illustrated in Figure 3.

Figure 5 shows a pressure chamber of the device in accordance with the invention in a top view.

Figure 6 is a sectional view of the pressure chamber and seals placed in it in a situation in which the pressure chamber is unpressurised.

Figure 7 is a sectional view of the pressure chamber and seals placed in it in a situation in which the pressure chamber is pressurised.

Figure 8 is an axonometric view of an application of the device of the invention provided with a protective frame.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. 1 is a sectional view of frame structures of a press section when viewed in the machine direction. Support beams T extend between load-bearing beams R from a tending side HP to a driving side KP. Fabric feed devices 100, 200 are mounted in the load-bearing beams R of the tending side HP. Fig. 2 is an axonometric view of the fabric feed device 100, 200 in accordance with the invention. The device is formed of two units 100, 200 placed one on top of the other.

Fig. 3 shows one unit 100 of the device in accordance with the invention. Each unit 100, 200 comprises a first side frame 101 and a second side frame 102 spaced from the first side frame. The side frames 101, 102 are substantially rectangular, elongated pieces. A first roller 110 is attached to first ends 101a, 102a of the side frames 101, 102, and a second roller 120 is attached to second ends 101b, 102b of the side frames 101, 102. An endless band loop 130 rotates around the rollers 110, 120 and runs between the side frames 101, 102. Shafts 111, 121 of the rollers 110, 120 are attached to bearing housings 112a, 122a, and the bearing housings 112a, 122a are in turn attached to the ends 101a, 101b of the side frames 101, 102. The height h of the side frames 101, 102 is slightly greater than the diameter of the rollers 110, 120 plus the thickness of the band 130 multiplied by two. The first 110 and/or the second 120 roller can be provided with a drive, for example, by means of a drive motor arranged inside the roller 110, 120. A pressure chamber 300 is disposed between the side frames 101, 102, the band 130 running over said pressure chamber. The side frames of the upper unit 200 of the device are attached to a load-bearing beam R of the tending side HP of the machine on the upper side with respect to the device, and the side frames 101, 102 of the lower unit 100 of the device are attached to a load-bearing beam R of the tending side HP of the machine on the lower side with respect to the device. The side frames 101, 102 of the units 100, 200 of the device can be attached to each other when the machine is operated, for example, by means of eye nuts suitable for the purpose and easy to detach in connection with a fabric change (not shown in the figures).

Fig. 4 shows a variant of the unit shown in Fig. 3. In this embodiment, a roller 110 is used only at one end of the unit. At the opposite end there is, instead of a roller, a curved surface 125, over which a band 130 runs. In this case, a drive is in the roller 110 situated at the one end of the unit. Fig. 5 shows a pressure chamber 300 in a top view. The pressure chamber 300 is formed of a rectangular piece attached at its edges to the side frames 101, 102 of the unit. A rectangular groove 301 having rounded corners is formed in that surface of the pressure chamber 300 which is positioned against the inner surface of the band 130. In the area defined by the groove 310 within itself there is an inlet opening 302 for a pressure medium. At the inner edge of the groove 301 there is a first seal holder 330 and at the outer edge of the groove 301 there is a second seal holder 340. The seal holders 330, 340 are fixed by fixing means, preferably by screws 331, 341 to the pressure chamber 300.

Figs. 6 and 7 show a cross-section of the groove 301 of the pressure chamber and of the seals placed in the groove. Fig. 6 depicts the pressure chamber in a rest position, i.e. in an unpressurised position, and Fig. 7 depicts the pressure chamber in a pressurised position. A first seal 310, whose cross-section is substantially round, i.e. it can also be a rounded polyhedron, is mounted on the bottom of the groove 301 having a rectangular cross-section. A second seal 320, whose cross- section is substantially in the shape of an inverted letter T or a shaped joint with shoulders limiting the displacement of the seal by means of the shoulders in a corresponding manner, is mounted on the first seal 310. This second seal 320 forms a slide seal for the steel band 130. In the rest position the first seal 310 is compressed, whereby it produces a lifting force for the second seal 320. This lifting force presses the second seal 320 into contact with the inner surface of the band 130. When a pressure medium is fed from the pressure medium inlet opening 302 shown in Fig. 5 into the pressure chamber, the pressure medium spreads into a space between the surface of the pressure chamber and the band 130 and further into the groove 301. In the groove 301 the pressure medium causes a lifting force for the second seal 320, whereby the second seal 320 rises upwards in proportion as the pressure medium raises the band 130 and the load situated on the band. When shoulders 320a, 320b of the second seal 320 come into contact with the seal holders 330, 340, the rising movement of the second seal 320 stops. Then, an increase in the pressure of the pressure medium no longer raises the band 130 and the load on it, but, instead, the pressure medium discharges from between the second seal 320 and the band 130 out of the pressure chamber. A slide surface is thereby formed of the pressure medium between the second seal 320 and the band 130, the band 130 sliding almost without any friction over the second seal 320.

In accordance with the application shown in Fig. 8, the device of the invention can be provided with an outer frame 400, which forms a protection for the device according to the invention. The outer frame 400 comprises an upper frame 410 and an extension part 420 of the upper frame as well as an extension part 430 of a lower frame. Spacer blocks 415 and 416 can be arranged in the extension part of the upper frame and the lower frame. The parts of the outer frame 400 protect the device 100, 200 in accordance with the invention and the extension part 420 of the upper frame also protects the device when the device is not in use. The extension part 430 of the lower frame also protects and surrounds the device. The spacer blocks 415 and 416 possibly arranged between the extension part 420 of the upper frame and the extension part 430 of the lower frame are removed when the device and/or separate jacks 405, 406 lift the parts 420, 430 apart from each other. The jack parts 405, 406 can be placed in connection with the device, when needed, for example, in a situation when the lifting distance of the device 100, 200 itself is not sufficient. In addition, in connection with the device it is possible to arrange a cleaning device 425 for the fabric to be pulled in, for example, at least one of the surfaces of the fabric is cleaned using a pneumatic or hydraulic means such that fabric-damaging particles cannot enter the feed-in nip. The use of this kind of cleaning device 425 is very advantageous, for example, when the device is used for feeding in a wire, in which connection even a small dry particle might make a hole in a thin wire. In connection with the device it is also possible to arrange a cleaning device, for example, a doctor or equivalent, for its bands. A door can also be arranged at the front side of the outer frame 400, which is indicated by the arrow 435, thereby enabling the structure to be closed completely from contamination splashing from the surroundings. When equipped with the outer frame 400 illustrated in the figure, comprising the upper frame extension part 420 and the lower frame extension part 430, the device can be replaced when fabrics are not being pushed into the machine because the frames and their extension parts carry the load. In that connection, it is advantageous to arrange, for example, rails in connection with the extension part of the lower or upper frame of the outer frame to replace the device. The rails can be, for example, of telescopic construction.

The operation of the device is described next. In the rest position, the units 100, 200 are in the load-bearing beam R of the tending side HP one on top of the other such that the load carried by the load-bearing beam R is transmitted to support points of the vertical frames R only through the side frames 101, 102 of the units or through the frames surrounding the device. The bands 130 of the units are not subjected to any load. When the pressure chamber inside the lower unit 100 and the pressure chamber inside the upper unit 200 are pressurised, the load is transferred from the side frames of the units to the pressure chambers and to the bands. The side frames are separated from each other to the extent that there is room for a fabric to pass between them, and the pressure medium between the pressure chamber and the band carries the load. Between the units, the band is subjected only to the friction caused by the pressure medium, said pressure being very small. The fabric can now be pushed into the throat between the bands, wherefrom it is transferred between the bands through the device. A drive motor is coupled to at least one roller of one band for pulling the band and, with it, the fabric through the device. When the fabric is pushed into the throat between the bands, a suitable wedge piece can be used ahead of the fabric in order that the fabric may be brought more easily between the bands without the inlet edge of the fabric being damaged. Such a wedge piece can also be used at the trailing edge of the fabric so that the trailing edge of the fabric should not be damaged when the fabric is transferred through the device. In the embodiment shown in Figs. 2-3 there is a roller 110, 120 at both ends of each unit 100, 200 and in the embodiment shown in Fig. 4 one roller 120 is replaced with a curved slide surface 125. It may also be contemplated that the rollers at both ends of the unit are replaced with curved slide surfaces. In that case, the fabric is placed between the bands 130 and pulled with the bands 130 to the inner side of the load-bearing beams R on the tending side HP of the machine. The pressure chambers 300 are then pressurised such that the side frames 101, 102 of the device are separated from each other, and the pressure medium of the pressure chambers 300 and the bands 130 carry the load. The pulling of the fabric placed between the bands through the device can then be accomplished using conventional means, for example, a block and tackle or a winch.

The band 130 is advantageously made of metal, such as steel, but a polymer fibre band can also be used. A liquid, such as water or oil, can be advantageously used as the pressure medium of the pressure chamber 300, but gas is also possible.

The seal holders 330, 340 are also advantageously formed of metal.

Because of the rectangular groove 301, the pressure area of the pressure chamber 300 can be made to match the area of the rectangular band 130 well, but any other polyhedron-, circle- or oval-shaped groove 301 is also possible. There can also be several chambers although it is more advantageous to accomplish one chamber.

The material of the first seal 310 is advantageously rubber and the material of the second seal 320 is advantageously graphite.

Above, the invention has been described in connection with a press section, which is one advantageous site of application of the invention. However, the invention can be applied in all web- forming equipment having changeable fabrics. The various details of the invention may vary within the inventive idea defined by the claims set forth below and differ from those given above by way of example only.

Claims

1. A method for changing a fabric in a paper or board machine, which method comprises the following steps: - arranging at least one device in load-bearing support beams (R) of a tending side (HP) of the machine for changing a fabric, which device is formed of two units (100, 200) placed one on top of the other, each unit comprising a first side frame (101), a second side frame (102) spaced from the first side frame, and a band (130) running between the side frames (101, 102), characterised in that the method additionally comprises the following steps:

- arranging a pressure chamber (300) between the side frames (101, 102) of each unit (100, 200), which pressure chamber is attached to the side frames (101, 102) and sealed against the inner surface of the band (130),

- pressurising the pressure chamber (300), whereby the load carried by the load- bearing support beams (R) of the tending side (HP) of the machine is transferred away from support of the side frames (101, 102) of the device onto support of pressure mediums of the pressure chambers (300) and onto support of the bands (130),

- transferring the fabric between the bands (130) to the inner side of the load- bearing support beams (R) of the tending side (HP) of the machine.

2. A method as claimed in claim 1, characterised by the steps of arranging a first roller (110) at first ends (101a, 102a) of the side frames (101, 102) and a second roller (120) at second ends (101b) of the side frames (101, 102), and forming the band (130) into a closed band loop rotating around the rollers (110, 120).

3. A method as claimed in claim 2, characterised by the step of arranging a drive for at least one roller (110, 120), the fabric being transferred between the band loops (130) while pulled by at least one band loop (130) to the inner side of the load-bearing support beams (R) of the tending side (HP) of the machine.

4. A device for changing a fabric in a paper or board machine, which device comprises two units (100, 200) placed one on top of the other, each unit comprising a first side frame (101), a second side frame (102) spaced from the first side frame, and a band (130) running between the side frames (101, 102), characterised in that each unit (100, 200) additionally comprises a pressure chamber (300) attached to the side frames (101, 102) and positioned in a sealed manner against the inner surface of the band (130).

5. A device as claimed in claim 4, characterised in that the device additionally comprises a first roller (110) attached to first ends (101a, 102a) of the side frames

(101, 102) and a second roller (120) attached to second ends (101b) of the side frames (101, 102), the band (130) being formed of a closed band loop (130) rotating around the rollers (110, 120).

6. A device as claimed in claim 5, characterised in that the pressure chamber

(300) comprises a rectangular plate in the surface of which there is a groove (301) forming a closed loop and an inlet opening (302) for a pressure medium in the area which the groove (301) forming a closed loop defines within itself.

7. A device as claimed in claim 6, characterised in that on the bottom of the groove (301) there is a first seal (310), which is round in cross-section, and on top of the first seal (310) there is a second seal (320), which is provided with a shaped joint with shoulders, a vertical arm of an inverted letter T of the second seal (320) forming the sealing of the pressure chamber against the inner surface of the band loop (130).

8. A device as claimed in claim 7, characterised in that at a first edge of the groove (301) there is a first seal holder (330) and at a second edge of the groove

(301) there is a second seal holder (340), which cover the groove (301) partly such that there is room for the vertical arm of the inverted letter T of the second seal (320) to move in a gap between the seal holders (330, 340) in the depth direction of the groove (301), so that the shoulders (320a, 32Ob)) formed by the horizontal arms of the inverted letter T of the second seal (320) limit the movement of the second seal (320) in a direction outwards from the groove (301) when the shoulders come into contact with the seal holders (330, 340).

9. A device as claimed in any one of claims 4 to 7, characterised in that the device (100, 200) is arranged inside an outer frame (400) protecting the device, which outer frame (400) comprises an extension part (420) of an upper frame and an extension part (430) of a lower frame.

10. A device as claimed in claim 9, characterised in that the outer frame (400) of the device (100, 200) comprises a door arranged on a front side (435) of the device.

11. A device as claimed in claim 9 or 10, characterised that spacer blocks (415,416) are arranged between the upper frame extension part (420) and the lower frame extension part (430) of the device (100, 200).

12. A device as claimed in any one of claims 9 to 11, characterised in that jack parts (405, 406) are arranged in connection with the side frame parts (101, 102) of the device (100, 200) to increase the distance of transfer.

13. A device as claimed in any one of claims 9 to 12, characterised in that a rail structure, preferably a telescopic rail structure, is arranged in connection with the outer frame (400) of the device (100, 200) for moving the device (100, 200) for replacement and/or for maintenance.