FI119599B - A system for replacing a fabric / belt with a forming machine, a lift used for replacing a fabric / belt with a forming machine, and a method for replacing the fabric / belt in a forming machine - Google Patents

Description

SYSTEM FOR CHANGING WOVEN / BELT ON A BREAKING MACHINE, FOR LIFTING A WOVEN / BELT ON A BREAKING MACHINE AND A METHOD FOR CHANGING A BREAKING MACHINE

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The invention relates to a system for replacing a fabric / belt with a web forming machine comprising a closed-loop forming fabric / belt, vertical beams for supporting the fabric / belt loop rolls and equipment 10, and an openable intermediate structure between the vertical beams, and a spacer including a and, in the system, the fabric / belt is arranged to pass through a spacer 15 while the pressure chamber is pressurized with medium. The invention also relates to a corresponding hoist and method.

Methods in which the body of a paper machine is provided with removable spacers are known in the art. These spacers are removed to replace the closed loop tissue. Generally, the drive side of the body is provided with beveling beams to support the body after removal of the spacers. Edge wrapping is a robust solution with solid structures to deliver desired tension to the desired foundations of the paper-machine hall. It is well-known that we want to abandon the tablecloth, as its implementation entails considerable costs. There will be cost savings as the foundations of the paper machine hall are lighter and less construction space is required.

For example, the cornice roll may be replaced by a solution according to patent FI 103421 in which a special tissue penetration device is provided between the vertical frame beams on the treatment side of the forming machine. In the drive unit, the drive unit acts as a traction unit surrounded by a belt. The drive unit allows 35 corners to be dropped, but is complex in design and contains many wear parts. In addition, the parts are custom-made, with few manufacturers.

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In addition, the fabric is subjected to mechanical compression as the weight of the trunks is transmitted over it. In this case, the tissue may be damaged by mechanical compression. When using a track structure, dirt can be trapped on the belt surrounding the track and can damage the replaceable tissue.

Edge roll may also be replaced, for example, by the solution disclosed in WO 2006/106178. In this case, the gap between the frames is created by a pressure chamber, which is limited to the ίο rib that touches them. In turn, the tissue on the other surface of the strip is passed through a gap formed. In the embodiments disclosed herein, sealing the sealing members against the tape is by no means straightforward. The necessary parts are also custom-made. Further, in the embodiments shown, seal 15 forms a boundary to the strip surface. When pulling the fabric through this boundary, there may be a limit lubrication situation in the gasket which impedes tissue penetration when the chambers are pressurized. For this reason, a gap between the chambers must first be created for the tissue at the point of stinging. After penetration, the chambers may be pressurized. 20 This procedure slows down tissue turnover. Therefore, it is necessary to create a novel system in which the replaceable tissue can be drawn between pressurized chambers. The solution of WO2006 / 106178 also requires a band between the replaceable tissue and the chamber.

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It is an object of the invention to provide a novel system for replacing fabric in a web forming machine which can be better adapted to various applications. Characteristic features of the method of the present invention are that the pressure chamber between the peripheral surfaces comprises a sliding surface having one or more flow openings having an outer surface and the flow openings being adapted to open on the outer surface to form a sliding layer by the discharge fluid. It is also an object of the invention to provide a new type of lift having a simpler structure to replace the fabric in the forming machine. Characteristic features of this elevator according to the invention are that the pressure chamber between the peripheral surfaces includes a sliding surface having an outer surface and flow slots on the sliding surface, and a sliding layer with medium 5a adapted to discharge from the sliding surface openings. It is a further object of the invention to provide a novel method of replacing a closed loop forming fabric in a forming machine in which the fabric can be drawn between pressurized chambers. A feature of the method of the present invention is that a sliding surface with one or more flow openings having an outer surface is used in the pressure chamber between the peripheral surfaces and the flow opening is adapted to open to the outer surface and a sliding layer is formed with the fluid.

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The web forming machine has a number of closed-loop fabrics that need to be replaced as needed. The replacement may be carried out using the method of the invention to replace the fabric in the forming machine. For purposes of this application, web forming machine 20 refers to machines for making paper and board with interchangeable fabrics. These include paper, board, tissue and pulp machines and belt calenders. Closed loops include wires on the forming section and felts on the pressing section 25. The web forming machine includes a closed-loop fabric, which may be, for example, a calender belt. Calendering straps can also be metal. The tissue is indirectly supported for tissue rotation by rollers supported on the vertical beams of the body. Between the vertical beams is an openable intermediate structure 30. The intermediate structure used to form a slot for changing the fabric of the web forming machine between the vertical frame beams of the service side. The intermediate structure includes a hoist with a pressure chamber. The pressure chamber is partially delimited by edge surfaces. The pressure chamber is pressurized with medium and the tissue is passed through a riser in the intermediate 35 structure. In addition, the pressure chamber includes a sliding surface having an outer surface between the peripheral surfaces. The sliding surface 4 has flow openings, and a sliding layer is formed on the outer surface of the sliding surface with a medium which is discharged from the flow openings in the sliding surface. In this case, the gap formed between the bearing beams is maintained by the pressure of the medium. In addition, said slot 5 may be formed by the pressure of the medium. It is essential for the invention that the gap is maintained at the pressure of the medium during tissue replacement. The tissue can then be guided through the gap between the beams. After formation, the gap is maintained by a hoist. The tissue may be introduced into or out of the web forming machine 10. The tissue is passed through the gap formed at its simplest by pulling the tissue from the edge of the tissue. Adhesive means may be added to the edge of the tissue to facilitate retraction. The gripping means may still have strings attached and further winches to facilitate pulling. 15

In one embodiment, the pressure chambers maintain a gap and the tissue is drawn into the gap defined by the pressurized pressure chamber. This embodiment is very advantageous, since no separate actuators are needed to form a gap in the device. Compared to the prior art, this embodiment is made possible by the novel design of the edge surfaces. In other words, the elevator according to the invention enables the tissue to be drawn into the gap, which is maintained by the elevator without separate actuators. With the gap maintained without the actuator 25, tissue replacement can be accomplished more simply.

Fig. 1 is a perspective view of a structure of a press section of a web forming machine comprising lifts according to the invention 30,

Figure 2 shows a web-forming machine, the machine direction of the side and front side beams, which beams between the front side is lifters in accordance with the invention;

Figure 3 illustrates an embodiment of a hoist 35 in accordance with the invention, 5

Fig. 4a shows a machine of a parallel lift according to the invention with the tissue in the gap,

Figure 4b is a transverse sectional view of the lift shown in Figure 4 with the fabric in the slot 5 Figure 5 shows an intermediate structure when the lift is in a non-pressurized condition,

Figure 6 shows the intermediate structure dismantled,

Figure 7a shows an embodiment of a hoist having only a band around one of the pressure chambers, Fig. 7b shows an embodiment of a hoist having no band around either of the pressure chambers,

Fig. 7c shows an embodiment of a hoist having a sealing means on one side and a pressure chamber having a sliding surface on the other side; and Fig. 7d shows an embodiment of the hoist according to the invention with larger rolls than in Fig. 7a.

Figure 1 shows a press section 12 of a web forming machine. The press section 12 is provided with a system 20 according to the invention for replacing fabric with a web forming machine. The press nip 14 is formed between the upper roll 16 and the lower roll 18. Figure 1 illustrates the web forming machine seen from the operating side of the machine keskeskeltä in the transverse direction, wherein the side beams 21, consisting of vertical beams 20 and horizontal beams 22, 25 are coated with far through the rollers. The weight of the tracks and equipment is supported especially by the vertical beams, which may also be skewed. Beams bearing in the direction of gravity are referred to as vertical beams without limiting their shape or position. The fabric 24 on the press portion 12 is supported in a closed loop 30 by rollers 16, 18 and 19. The rolls 16, 18 and 19, in turn, are further supported by a frame consisting of beams 21, more particularly vertical beams 20 and horizontal beams 22. between the side beams 20 are an openable intermediate structure 26. The intermediate structure in connection with a lifting device 10, which is partially defined by edge surfaces 30. The pressure chamber 35 with the fabric is adapted to be taken through the intermediate structure while the pressure chambers 6 tettuina pressurized medium. Further, Figure 3 shows that the pressure chamber 30 between the peripheral surfaces 32 includes a sliding surface 31 having one or more flow openings with an outer surface. The flow apertures are arranged to open on the outer surface to form a sliding layer 37 in a fluid discharged from the flow apertures. In the situation shown in Fig. 1, the elevators 10 are out of service and the fabric 24 is stationary on the press portion 12. In turn, when transferring the fabric to or from the forming machine, the fabric is introduced through the gap 10 formed by the elevator. By tissue is also meant a piece of tissue attached to the tissue, which can be used to guide the tissue between the sealing members. The tissue may also include sealing and shielding surfaces, which may cover the entire width of the tissue. When the hoist 10, which is an intermediate lift, is used, the pressurized medium 34 is introduced into the pressure chamber 30. The medium 34 is introduced into the pressure chamber 30 via a conduit 36. Pressurizing devices 28 are required to pressurize the medium 34. By pressurizing the medium with the pressurizing devices, the chamber is indirectly pressurized. The pressure generating devices may be provided separately for operating the hoist 20 or the pressure may be taken from the factory network. Figure 1 shows a number of possible positions of the elevator 10, but nevertheless the application of one of the elevators in a tissue cycle is possible.

25 Figure 2 shows a view of a web forming machine in the machine direction of the press section or a forming section drive side 38 vertical beams 40 and front side 42 vertical beams 20 of the web forming machine, the press or forming section-side 20 42 between the vertical beams are arranged lifters in accordance with the arrangement described above 10. 30 in Figure 2 lifters 10 are turned off, or non-pressurized. The load then rests on the supporting structures in the intermediate structures 26.

Figure 3 illustrates one embodiment of the inventive elevator 35 used for changing the fabric 35 by a web forming machine. Further, the pressure chamber between the peripheral surfaces includes a sliding surface 31 having an outer surface, and the sliding surface 31 has flow openings. A sliding layer 37 is arranged on the outer surface of the slide member 5 with a medium adapted to discharge from the flow openings in the slide surface 31. The hoist maintains the gap needed for tissue delivery at medium pressure.

When using the hoist 10 shown in Figure 3 in the system of the invention, the fabric 24 is passed through the intermediate structure, or more particularly the hoist 10, with the sliding surface 31 fitted against the web 39 included in the hoist. Preferably, the surface of the strip against the sliding surface is low-friction. Then even a slight pressure 15 is sufficient to create both the required gap and the sliding layer. For example, the tape surface may be teflonized to reduce friction. In turn, the other surface of the tape preferably has a higher friction, whereby the rotation of the tape helps to pull the fabric through the elevator. Also, in a non-usable application, the fabric-side surface of the strip 20 may be rough so that the strip and the fabric pass together through the structure.

The hoist shown in Fig. 3 includes guides 41 for supporting the tape 39. Here, the guides 41 are rollers 43. With the guides 41 25 being rollers 43, it is very practical to use a loop forming loop. The rolls may be usable or idle. Useful rollers allow the tissue to be slit without external actuators to form the slit. In other words, the working rollers allow the fabric to be pushed directly between the pressurized pressure chambers. In turn, when the rollers are idle, a very simple embodiment is achieved in the overall construction.

Figure 4a shows a view from the treatment side of the elevator 35 of the invention with the tissue 24 in the gap 45, i.e. between the pressure chambers 30. The figure shows a strip 39 supported by the rollers or guides 8. In the situation of the figure, the pressure chambers 30 are pressurized. Regulator 10 may be connected to the front side 42 vertical beams 20 (Figure 2), in which case it maintains a gap between the front side vertical beams.

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In turn, Fig. 4b shows a transverse cross-section of the hoist 10 according to the invention. The cross-section is taken so that the pressure chamber is shown in cross-section. The fabric 24 is located between the pressure chambers 30 and the pressure chambers 30 are pressurized. More specifically, the fabric 24 is disposed between the bands 39 on the outer surfaces 35 of the sliding surfaces 31. The strips are between the sliding layers 37 forming the fluid 34 on the sliding surfaces 31. Of course, in reality, the strips also partially touch the sliding surfaces themselves. As a whole, the thickness of the sliding layer in Figure 4b is exaggerated for the purpose of illustrating the principle. At high flow and pressure, the thickness of the sliding layer increases, but there is no need to obtain the spacing as shown in Figure 4b. Obtaining an unnecessarily thick sliding layer requires unnecessarily high pressure and 20 flows.

The elevator 10 shown in Fig. 4b comprises two pressure chambers 30 with their sliding surfaces 31 facing each other. In this embodiment, the fabric 24 is arranged to be introduced between the pressure chambers 30 while the pressure chambers 30 are pressurized with medium.

As shown in Figure 4b, it is clear that the edge surfaces 32 rise up when pressurized, since the pressure pushes the sliding surface 31 out-30, i.e. away from the back surface 47. The pressurized medium in the pressure chambers 30 maintains the gap as it flows out of the chamber through the flow openings 33 in the sliding surface 31. As the peripheral surfaces 32 move away from the background surface, the chamber 30 can be pressurized to provide a structure in which the chamber occupies a very small space when the pressure is released. In this case, such a lifter takes up very little space during operation of the forming machine.

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Fig. 5 shows a hoist 10 according to the invention in the operating state of the web forming machine. The pressure chambers 30 are then unpressurized and the supporting structures are joined. During operation of the forming machine, the frame is supported by a protective structure 48 in connection with the lift-5 member 10 and the actual supporting structures. The main purpose of the protective structure is to prevent the user from inserting his or her fingers into the hoist when the pressure chambers are pressurized. By dimensioning, the edges of the protective structure are arranged to coincide as pressure is removed. In this case, the protective structure of the ίο serves as a supporting structure. The actual supporting structures are around the hoist. The supporting structures can also be on several sides of the hoist. The hoist can be implemented in many ways according to the invention as well as the supporting structures. It is essential that the hoist has 15 sliding surfaces with flow openings. A sliding layer is formed on the sliding surface of the chamber with a medium adapted to discharge from the flow openings in the sliding surface. When the chamber is depressurized, the chambers no longer support the frames, thereby supporting the supporting structures.

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The intermediate structure and the hoist shown in Figure 5 are arranged in a single structure, which is removably attached between the vertical beams as a whole. This makes changing the hoist for maintenance easier.

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The dimensions of the sides a and b of the hoist shown in Figure 5 are approximately 900. In turn, the height c of the hoist is 400 mm. The pressure chamber has a diameter of about 700 mm.

30 The medium used in the hoist is gaseous, so that it is not absorbed by the interchangeable tissues while being hydrated. Preferably, the medium is ordinary pressurized air so that it can be freely released into the hall space. The air can be drawn from the factory mains or pressurized with a separate compressor. Preferably, 35 is pressurized with an inexpensive compressor since the required pressure level can be, for example, 3 bar and the required flow rate is 10 m3 / min per hoist.

Fig. 6 shows a hoist according to the invention in disassembly. In this case, the main components of the 5 lifts can be seen in more detail. In particular, the structure of the pressure chamber 30 is shown. The pressure chamber 30 consists of an edge surface 32 and a sliding surface 31. An edge surface 32 surrounds the sliding surface 31 on all sides. The shape and structure of the edge surfaces and the sliding surface can be very diverse. It is essential that the fluid can be discharged to the sliding surface from the flow openings on the sliding surface. There may be one or more flow openings from which the medium discharges. In the exemplary embodiment of Figure 6, there is one flow port 33. As a rule, the sliding surface may be in one or more planes. In the case of Fig. 6, the sliding surface 31 is divided into three portions, which in Fig. 6 are the peripheral portion 50, the middle portion 52 and the aperture portion 54. The peripheral portion 50 is lower than the middle portion 52. Accordingly, the aperture portion 54 is lower than the middle portion 52. adapted from the flow opening 20 in the discharge opening portion 54. Also, the higher central portion of the sliding surface may have flow openings. The pressure chamber 30 is adapted to be located further within the belt loop formed by the rolls 43 supported by the rollers 43. When the pressure chamber 30 is disposed within the ribbon loop formed by the strip 39, the sliding surface 31 is in contact with the inner surface of the ribbon loop formed by the strip 39.

In Figure 6, the sides of the hoist frame have shapes for fastening means. These designs make it easy to attach the lift. Further, the intermediate structure 26 and the hoist 10 are arranged in a single structure which can be detachably attached between the vertical beams as a whole. This allows the lift to be dismounted in its entirety. In this case, the lift itself is an assembly that is replaced if necessary.

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The lift according to the invention shown in Figure 6 can be implemented with a simple overall construction. It is also possible to replace individual components, such as a pressure chamber. The pressure chamber is of the "Air cushion" type, whereby the medium discharged therefrom, i.e. air, creates a sliding layer in connection with the pressure chamber.

Figures 7a-7c illustrate various embodiments of the hoist 10 according to the invention. Each has its own merits and is well suited to a wide range of applications. In the embodiment shown in Figures 3-6, two chambers are provided, and a slit is provided along the sliding surfaces of both chambers. This is not the case in Figures 7a-7c.

Figure 7a shows an embodiment having two pressure chambers 30 having a sliding surface 31 of a flow orifice 15 facing each other. Of these, the sliding surface 31 of the lower pressure chamber 30 is provided with a band 39 supported by the guides 41, more particularly by rollers 43, said band may be operatively rotatable or idle. The utility helps, for example, in inserting tissue between the sliding surfaces 20 without the separate actuators required to create a gap.

Figure 7b shows an embodiment in which the sliding surface 31 of the elevator 10 is fitted against the fabric 24 when passing the fabric 24 through the intermediate structure. The hoist has two pressure chambers 30 having a flow orifice 33 25 with a sliding surface 31. By using the flow chamber 33 pressure chambers 30 facing each other without a strip, a very simple embodiment is achieved. When the hoist 10 is in a pressurized state, the fabric 24 is against the sliding surface 31. More particularly, the fabric 24 is supported by a sliding layer 37 formed by a medium 30 on the sliding surface 31. The lifting effect of the medium then maintains the gap 45. In other words, 24 is not formed between the outer surface 31 of the sliding surface, but the tissue fluid tight sliding layer 37. The essential thing is that the medium pressure can keep the vertical beams between the paper 35 of the machine-side isolation.

12 This leaves a gap between the vertical beams from which the fabric can be drawn. The chamber structure of the hoist is not tight and the medium leaks in a controlled manner. In addition, the medium may be transported through the tissue. With suitable sizing and medium pressure 5, the lift operates as intended despite the leaks.

Preferably, the press section, in which the replaceable fabric is felt, provides pressure through two pressure chambers. In other words, the medium is led from the opposite pressure chambers to both, whereby both chambers have a channel for introducing the medium. Then both chambers are directly pressurized. Such a structure is necessary because not all the felts used are permeable to the medium for unilateral pressure application. In other words, duplex pressure imports allow for a list of impermeable tissue on both sides of the same pressure. In this case, the pressurized medium lifts the surfaces apart without exerting tissue damaging forces.

Fig. 7c shows an embodiment having a pressure chamber 30 having a sliding surface 31 of a flow orifice 33 above the fabric 24 and in turn a pressure chamber 30 'below the fabric 24 defined by sealing members 55. This embodiment can be used in conjunction with a medium permeable tissue. The medium then exerts a pressure on both pressure chambers on which the body rests. The tissue can then be drawn through the gap 45. Thus, the elevator according to the invention can have only one sliding surface chamber.

Fig. 7d shows an embodiment having two pressure chambers 30 having a sliding surface 31 of a flow port 30 facing each other. Of these, the sliding surface 31 of the lower pressure chamber 30 is provided with a band 39 supported by rollers 43, the first of which is on the machine side of the pressure chamber and the other of the rolls viewed from the pressure chamber on the treatment side of the forming machine. Such an arrangement is advantageous in connection with useful rolls, in order to obtain a large contact area between the fabric and the strip.

When passing the fabric through the intermediate structure, the sliding surface is fitted against the 5 tissues. In other words, the sliding surfaces are immediately in contact with the tissue, whereby the pressure of the medium separates the tissue and the sliding surface or the surface of the tissue and the strip. The term sliding surface refers to surfaces other than planes. The surfaces may as well be inwardly curved, for example. 10 Surfaces can also be micro-shaped. Microforming can improve the sliding of the fabric between the sliding surfaces. The surfaces are broadly defined as the area on which the pressure in the hoist is applied to provide the lifting force.

15 The lift has two surfaces between which pressure is applied. Pressure can be applied between the surfaces through one or two surfaces. With the forming part having the fabric to be replaced, the pressure can only be applied through one surface, more specifically the pressure chamber 30 (Figure 7c). In other words, the medium 20 is guided only from one of the opposed pressure chambers, whereby only one chamber is provided with a channel for conducting the medium. Such a simple structure is possible because the wire passes through the medium and pressure is applied between the pressure chambers of the hoist. Although only one of the chambers is pressurized directly, indirectly, through the wire, both chambers are pressurized.

A constant pressure is applied to the sliding surface. The pressure can be offset, inter alia, by introducing the medium through a plurality of channels 30. However, multiple channels in one chamber may make the structure complex. The shape of the pressure chamber may also be utilized to balance the pressure. The pressure chamber may, viewed from above, be circular or at least rounded at the corners. The more angular shape may be, for example, 35 parallelograms, the corners of which are rounded with a large radius.

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Further, the shape of the pressure chamber may be, for example, oval. The shape can thus be very freely customized to the needs of the application. The shape without the tight angles achieves a more even pressure in the sliding surface area.

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It has been stated above that the tissue can be drawn into a slot which is maintained by a hoist. In such an embodiment, for example, the web being rolled on the drive rollers pulls the tissue into the gap. Such an embodiment is possible because the elevator according to the invention enables the mildly pressed wall surfaces of the pressure chamber.

It is not always possible to pull the tissue into the gap, which is maintained only by the lift according to the invention. In this case, a separate actuator may be used to form the gap 15 to insert the tissue into the gap. The actuator may be, for example, a bridge crane, a jack. The hoist according to the invention may also include gripping points. In this case, the actuator, which is a jack, can open a gap between the surfaces into which the tissue is inserted. Spreads can serve as sites of infection. The jack is used to increase the spacing between the spreads so that a gap is formed between the sliding surfaces and the tissue is placed there. Using the jacket is simple and the jacket is a reliable solution. In addition, the spreads required by the jacket are easy to manufacture.

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When a separate actuator is used to form the gap, actuator operation is discontinued when the tissue is obtained between the sliding surfaces in the hoist. Tissue refers to tissue in a very broad sense. For example, a tissue is thought to be a piece of tissue that is attached to a tissue. Such tissue glass can be used because in some situations it is easier to handle than tissue. The tissue may also include sealing and protective surfaces. The sealing surfaces help control the flow and limit the pressure to the desired area. In turn, 35 protective surfaces prevent tissue damage. Separate tissue fragments can prevent damage to the actual tissue. As a whole, the actuator can be used to create and maintain a gap until there is a tissue between the pressure chambers of the hoist. With the fabric between the pressure chambers, the pressure chambers arranged on both sides of the fabric can be pressurized. When pressurized, the edges of the pressure chambers move toward the tissue, whereby the hoist holds the formed gap, allowing the tissue to pass through the gap. Typically, in an embodiment where a separate actuator is used to form the slits, the chambers are pressurized prior to removing the actuator lifting action. This avoids mechanical stress that is otherwise temporarily applied to the tissue. Similarly, the arrangement shown may be implemented in reverse order when the tissue is removed from the slot. By actuating the actuators 15 to maintain the gap prior to depressurising the hoist, mechanical stress otherwise temporarily applied to the trailing edge of the tissue is avoided.

Preferably, the old tissue is removed from the machine intact. With the spreads 20 on either side of the hoist, the tissue can be inserted and removed without cutting. Turning off the old fabric extensions needed to lift the body only in the machine's front side frame, when the new fabric can be put in place without the use of Ylimaa-25 denominated pieces of fabric attached to the fabric.

The following describes how to replace a closed-loop tissue with a new one by utilizing a lift according to the invention without breaking the old tissue. First, from the machine, the actuator external to the body 30 forms a gap between the pressure chambers. This creates a gap between the support structures and the pressure chambers. The tissue is then threaded between the pressure chambers. When the tissue is completely in the area between the pressure chambers, the hoist is pressurized and the actuator is depressurised. When pressurized, the pressure chambers form a sliding layer on their sliding surface. The hoist maintains a gap between the pressure chambers from which the tissue is drawn. The fabric is then pulled away from the machine between the pressure chambers and thus the sliding surfaces. Even with the tissue removed, the pressurization of the pressure chambers is maintained and the surfaces remain separated until the pressurization of the chambers is removed. Thus, there is a sliding layer between the sliding surfaces which keeps the sliding surfaces separate. After removing the old tissue, replace the new tissue with the old tissue. The insertion of the new tissue is initiated by forming a slot 10 between the pressure chambers in the hoist by means of a machine-side actuator. The tissue to be placed on the machine is inserted into the gap thus formed. When the fabric is in the gap, the hoist is again pressurized and the roller side actuator of the web forming machine is depressurized. After removal of the actuator, for example a jacket, the tissue is retracted. Finally, the pressure chambers are depressurized and the supporting structures joined. The web forming machine is then ready for use again. Support structures may include separate support blocks that allow a wider gap in the machine frame.

20 The mode of operation described in the previous paragraph is only one option and can be varied as required. If there is a risk of tissue damage when the tissue is withdrawn between pressurized pressure chambers, the gap between the pressure chambers may be maintained with an actuator before the tissue edge is removed. In this case, the tissue is not subjected to any damaging forces. A tissue body may also be attached to the tissue, which ultimately comes between the pressure chambers. The potential damaging force is then applied not to the tissue but to the tissue body, and the tissue is restored intact without actuating the actuator at this stage. Any sealing and protective surfaces in connection with the tissue also prevent tissue damage. The protective surfaces may be, for example, metal surfaces that cover the fabric through the portion of the elevator. At the same time, metal shields act as sealing surfaces, although shielding is their actual function.

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The intermediate structure described above includes an actuator, and the tissue is inserted into a gap maintained by the actuator. In addition to the above, the actuator may be a hoist according to the invention. There are then at least two lifts in the transverse direction of the forming machine. The first hoist creates a gap between the pressure chambers in the second hoist. The tissue is then drawn into the formed gap. The second hoist is then pressurized and the first hoist is depressurized to draw the tissue into the gap 10 between the pressure chambers of the first hoist. The pressure chamber can thus be used as an actuator similarly to any other actuator.

In addition, the tissue to be removed from the forming machine can be cut. Thereby, the truncated tissue can be removed by crane 15 or pulled out of the machine into the basement without opening into vertical beams. In this case, in the case of tissue replacement, the hoist is only used when the new tissue is inserted.

There may be several hoists according to the invention in connection with one vertical beam also in the machine direction. This structure stabilizes their operation. In addition, the support structures may be shaped to be oriented, so that when the gap is closed, the support structures will direct the support structures to merge as desired.

One of the key advantages of the invention is that a similar structure can be used with many types of tissues. In addition, the invention also makes it possible to dispense with a large number of custom-made components, thereby making the manufacture of lift components more competitive. In practice, the replacement of the tissue occurs through a medium, whereby the exchange is almost frictionless. In other words, less force is required to transplant the tissue. The pressure on the tissue is also constant throughout the area delimited by the sealing members, thereby avoiding harmful pressure peaks.

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The hoist thus avoids the application of damaging force to the tissue.

It is also conceivable to direct the medium directly between planar low-friction and possibly microformed body surfaces to reduce friction. In this case, the body surfaces are sliding surfaces with flow openings.

Edge surfaces are understood to mean a wide variety of structures defining a sliding surface with a flow opening. The edges may be resilient, for example rubber. Such rubber edge surfaces are formed by pressure. The edge surfaces may also be shaped, for example metal. Metal edges do not significantly deform under pressure. The shape of the edge surfaces and the sliding surface may vary. Similarly, the material of the sliding surface of the peripheral surface may be deformable or non-deformable, such as steel or bronze. This depends on the application. It is essential for the invention that the sliding surface delimited by the edge surfaces has flow openings for the medium. Flowing medium reduces contact between opposing sliding surfaces. Significantly, the friction decreases even if no large gap is formed.

The frame lifting movement can be accomplished by various actuators and the elevator according to the invention is suitable, for example, for a metal belt calender with lightweight frame structures. Calender, the party may even carry / relieve the side of the load during the belt of exports. The medium pressure can be distributed on both sliding surfaces through a plurality of flow openings. The flow openings 30, i.e. the pressure ports, may be holes, possibly dents or depressions. The recesses can connect holes or other flow openings. Each flow orifice forms a small pressure chamber that supports the fabric / belt.

Claims (11)

A system for replacing a tissue / band in a sheet forming machine, comprising: 5. a tissue / band (24) forming an endless loop, standing beams (20) to support the tissue / band loop (24) rollers and equipment, and an openable intermediate structure (26) between the upright beams (20), and the intermediate structure (26) comprises a lift (10), further comprising a partial pressure chamber (delimited by edge surfaces (32)). 30), and in the system, the tissue / band (24) is arranged to pass through the intermediate structure (26) when the pressure chamber (30) is pressurized by a medium (34), characterized in that the pressure chamber (30) between the edge surfaces (32) comprises a slide surface (31) equipped with one or more flow openings (33) having an outer surface (35), and the flow openings (33) are arranged to open to the outer surface (35) to form a slide layer (37) with the flowing medium (34) from the bore openings (33). A system according to claim 1, characterized in that when the tissue / band (24) is passed through the intermediate structure (26), the sliding surface (31) is arranged against the tissue / band (24). A system according to claim 1, characterized in that when the tissue / band (24) is passed through the intermediate structure (26), the sliding surface (31) is arranged against the band (39) which is included in the lift 30 (10). 4. A system according to claim 3, characterized in that the surface of the belt (39) corresponding to the sliding surface (31) has little friction. 23 5. A system according to claim 3 or 4, characterized in that the lift comprises control means for supporting the belt. A system according to any of claims 1-5, characterized in that the medium (34) is gaseous. 7. A system according to any one of claims 1-6, characterized in that the intermediate structure (26) and the lift (10) have been arranged into a unitary structure which is removably fixed between the supporting beams (20). A system according to any one of claims 1-7, characterized in that the lift (10) comprises two pressure chambers (30), whose sliding surfaces (31) are provided with resistance to each other, and the fabric / belt (24) is arranged to is passed through the pressure chambers (30) when the pressure chambers (30) are pressurized by a medium (34). A lift to be used in exchange of a tissue / band in a sheet forming machine, comprising a pressure chamber (30) having edge surfaces (32), and the tissue / band (24) being arranged to pass through the lift (10) when the pressure chamber (30) is filled with a medium (34) which is pressurized, characterized in that the pressure chamber (30) between the edge surfaces (32) comprises a sliding surface 25 (31) which has an outer surface (35), and that it in the sliding surface (31), there are provided solder openings (33), and that on the outer surface (35) of the sliding surface (31), a sliding layer (37) is provided with the medium (34), which is arranged to flow out through the flow openings ( 33) located on the sliding surface (31). 30 A method of exchanging a tissue / tape in a sheet forming machine, and the sheet forming machine comprises a tissue / tape (24) forming an endless loop which is supported as a tissue / tape wrap with rollers resting on standing beams. (20), and between the upright beams (20), a 24 openable intermediate structure (26) is used which includes a lift (10) equipped with a pressure chamber (30), and the pressure chamber (30) is partially delimited by edge surfaces (32), and the pressure chamber is pressurized with a medium (34), and the tissue / band (24) is passed through the intermediate structure (26) when the pressure chamber (30) is pressurized, characterized in that it is used in the pressure chamber (30) between the edge surfaces (32). a sliding surface (31) equipped with one or more flow openings (33), said sliding surface having an outer surface (35), and the flow openings (33) arranged to open to the outer surface ίο (35), and with the medium flowing from the flow openings (33) (34) a gl id layer (37). A method according to claim 10, wherein a slot (45) is maintained with the pressure chamber (30), characterized in that the tissue / band (24) is drawn to a slot (45) defined by a pressure chamber (30) under pressure.