FI114031B - Method of pressing paper web and paper web press device - Google Patents

Description

1 114031

A method of clamping a paper web and a paper web clamping device

The invention relates to a method of compressing a paper web, wherein the paper web is guided through a nip formed between a flexible movable element forming an endless structure and a counter roll, the movable element being a flexible jacket or belt loop, the movable element being supported in the nip area against one roll shoe element. The invention also relates to a paper web clamping device. In this context, the paper web also refers to 10 webs of fibrous pulp having a basis weight in the area where the products are commonly known as carton.

The paper web formed by the wire section is pressed in a paper or board production line at two points: a press section where the wet pa-15 web is extruded by squeezing water, and a calender where the surface is finished by applying pressure to a relatively dry paper web. Although the press section and the calender have different purposes for pressing, the web has a very different dry solids content and the technological development of the aforementioned parts is guided by the phenomena affecting the paper, 20 having a common nip in which the web is subjected to a certain pressure the nip is formed by two moving surfaces, normally the diaphragm surfaces of two rotating rolls, • pressed against each other on both sides of the web.

j ·., 25 For example, in a shoe calender, a combination of a soft surface roller and a hard roller provides a nip that has a dimension in the longitudinal direction of the machine and the calendering paper web therefore has: The soft - surfaced roll shell is:. : formed of a flexible flexible belt and a hard surface roll is a 30 metal roll which is a heated roll and acts as a calender for warm. ···. table as a roll of thermo roll. Soft roll casing with load. It is pressed inside the roll against the hard roll by a loading shoe, which causes the paper web against the hard roll surface to be pressed over a long distance in a nip at a certain pressure between the soft shell and the hard roll pin 35. The flexible sheath can be compressed in the same thickness direction in the nip area. The belt forming the soft roll shell may be 2 114031 suitable elastic polymers, such as polyurethane, and has a reinforcing fabric within the belt. The nip structure allows good bulk and stiffness and uniform surface smoothness for paper and board. All in all, the calender is particularly well suited for on-line calendering of printable paper and cardboard grades. That type of calender is called the shoe calender and is known by the trade mark 'Opti-Dwell'. A further embodiment thereof is described in International Application WO 99/28551.

10 Long nip presses comprising a concave shoe element with a press section are in turn disclosed in Finnish patent 98843, to which e.g. U.S. Patent 5,908,536; U.S. Patent Nos. 5,084,137; 5,262,011; 5,639,351; and International Patent Application Publication No. WO 99/19562. In these so-called. within the hose reel, a shoe element to be loaded with a certain force is bent against the inner surface of the 15 roll sanitary roll and the web is passed through a nip formed between the hose reel and the counter roll with one or two press felts.

It is known to adjust the pressure on the paper web in a nip with hydraulic cylinders acting on the hand element of the ken-f 20 supported on a fixed shaft inside the diaper. The cylinders are usually arranged in two rows: ** and provide a linear load movement. Such loads ··. mitigation systems for adjusting the pressure of the calender nip are disclosed e.g.

: V. U.S. Patent Nos. 5,582,689; and 6,213,009; and mounted on a press roll, U.S. Patent 5,639,351.

From the Finnish patent 65103, corresponding to US patent 4,713,147, a way is known to change the position of the center of gravity of the shoe element in the machine direction, whereby the distribution of the dewatering pressure in the nip length-30 direction can be changed. In practice, this idea is realized by providing parallel pressure hoses that load the shoe with different pressure levels that can be independently adjusted.

The same tendency is disclosed in U.S. Patent No. 6,306,261, which has a concave shoe divided into segments of segment 35, the segments of which are articulated to each other can be individually loaded.

3, 114031

In fact, loading by means of two parallel rows of loading cylinders (in succession in the machine direction) or a loading hose is difficult to control (unless asymmetry is desired, unlike in U.S. Patent 4,713,147). An example of this is oblique or edged nip nip closures. Another problem with the known loading system has been the exact positioning required by the shoe.

The object of the invention is to eliminate the above drawbacks and to provide a method by which the loading in the nip through the shoe element can be carried out with greater certainty and the positioning of the shoe element is also more accurate. To accomplish this purpose, the method is essentially characterized in that the shoe element is supported at one point to a fixed pivot point and machine-spaced from another point at the pivot point to a loading member which forces the shoe element load and nip pressure and pivot pivot pivot respectively.

The pivot point is located in a fixed position through the nip and relative to the movable element passing over the surface of the shoe element. The pivot point is supported on 20 fixed frame structures, such as the fixed axis of the shoe roll. The body structure is also supported by a load member, which may be: ·. ·. a continuous load hose extending across the machine's transverse direction, or a corresponding row of load cylinders extending across the machine. There may also be several load members in different machine directions at different distances from the pivot point. The combination of a standard pivot point and one or more loading members provides support for an adjustable * ·· * tilt, which allows the nip pressure curve (pressure distribution along the length of the nip) to be changed during operation.

I * 30 The shoe element can be shaped with a back surface facing the nip. I ·. that it takes into account the occurrence of the above-mentioned pivot point

i I I

!!! va rotation in the vertical plane (perpendicular to the axes of the rollers).

The invention makes it possible to implement a movable shoe element, which, however, has better motion accuracy due to a fixed pivot point. The only variable affecting the load force 4114031 and thus the nip pressure is the force exerted by the loading members, which acts only at one point in the machine direction on the shoe element, either by means of an elongated load hose or a series of loading cylinders. Likewise, position (bridge) 5 need only be adjusted by a single loading member, while known solutions require two successive loading members in the machine direction.

The press device according to the invention, in turn, is characterized in that the shoe element is supported at one point to a fixed pivot point and in the machine direction at another point away from the pivot point to a loading member arranged to cause the shoe element to load and move relative to said pivot.

15

The loading member may be a cross-machine hose acting substantially at one point in the machine direction on the shoe element, containing a pressurized fluid whose pressure determines the loading force, or similarly a transverse row of loading 20 cylinders within which the pressurized medium prevails. The loading member may be supported by a fixed member: v. to the body with respect to which the pivot point is also fixed.

* ♦ »

According to one embodiment, the shoe element 25 may be attached to a support plate on which the load member is disposed on the opposite side and one of the edges is pivotable about said pivot point.

The solutions can be applied to both press nipples of the press section and calender nipples of the calender, although in the aforementioned parts of the papermaking process. ! ·. there are differences. The press section undergoes a significant increase in the dry matter content, typically after the wire section press nips from '*: · * 16-25% to 42-55%. In a calender where the dry matter content of the paper is no longer significantly increased, the dry matter content of the incoming paper is usually at least 85%.

5, 114031

A flexible moving element, which may be a so-called. The "hose reel" jacket or endless loop belt is capable of conforming to the shape of the guide support surface of the shoe element as it passes over the surface.

Again, a flexible moving element is meant to be a jacket or loop forming belt capable of being deformed by the loading pressure acting on the nip and providing a nip having a dimension in the direction of web travel.

10 The loading member loads the shoe against the counter-tree on the other side of the nip and thus affects the nip pressure. The loading member is adjustable in a known manner, whereby the magnitude of the load and consequently the nip pressure level can be adjusted.

The invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 is a side view of a calender in which the invention can be used, '·. Fig. 2 is a side view of a preferred embodiment for arranging the load in the calender of Fig. 1, Fig. 3 is a side view of another embodiment, Fig. 4 is a side view of a third embodiment, and Fig. 5 is a side view.

25 '*

Figure 1 shows a calender in which the invention can be used. The paper web W is guided through a calender nip N · 'formed between two rolls. The lower first roll 1 comprises a sheath 1a made of a flexible flexible material that rotates about the axis of rotation of the calender roll. The upper second roll 2 is a hard surface heated fish -. **. a blade roll, for example a roll with a metal sheath, which is harder than t ':' the flexible flexible material of the sheath. In its thickness direction (in the radial direction of the calender roll 1), the resilient sheath 1a is pressed into the shape determined by the surface of the shoe element 3 and the second roll 1 guiding the sheath, thereby forming a long nip N where the web W extends between the surface of the compressed diaper 6 114031 1a. The shoe-guiding surface of the shoe element 3 is convex and is a portion of a cylinder parallel to the axis of rotation of the calender having a radius of curvature and a corresponding center of curvature on nip N of the first roll 1. the axis of rotation converges. The guide surface of the shoe element 3 over which the shoe 1a slides may also be straight or concave, in which case the center of curvature of the surface is on the side of the second roll 2.

The shoe element 3 is loaded against the inner surface of the sheath 1a by a loading member which acts on the shoe element 3 with a certain load force F which is adjustable. The loading member and the attachment of the shoe element 3 will be described below, i.e. the cylinders may be hydraulic cylinders. The loading member is supported by an axial bearing member E inside the roll 1.

The nip contact by the action of the rollers 1 and 2 is not linear but has a certain dimension in the direction of travel of the web. This is a so-called. pit nipple N (extended nip).

i ·· 20: Figure 2 shows in more detail the attachment of the shoe element 3.

The shoe element 3 is arranged to pivot with respect to the pivot point P in the vertical plane. The pivot point P is supported on the support element E. Mechanically, the shoe element 3 moves relative to the pivot point P so that the points of the support surface toward its nipple move along circular paths centered on the pivot point P. The shoe element 3 is fixed relative to the pivot point that it forms a kind of single-arm lever having a pivot point: said pivot point P with the support surface of the shoe element 3 on the same side of the pivot point P. The forces at the various points along its length • v. 30 (machine direction) are determined by the

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. ·· *. according to the ment. The movement and, at the same time, the load force is provided by a loading member acting between the shoe element 3 and the support element E; · · 4 located in the machine direction (diaphragm 1a movement) away from the pivot point. is a pressure medium, preferably a liquid. By adjusting the pressure p of the pressure medium, the force F and the nip pressure acting on the 7114031 shoe element can be adjusted.

Structurally, the attachment and support of the shoe element 3 is implemented such that it is secured to the support plate 5, on the opposite side of which is a loading hose acting as a load member 4 disposed between the support plate 5 and the support element E. The edge of the support plate is attached to the support element E via a joint forming the aforementioned pivot point P.

10 In Figure 2, the shape of the shoe is concave and can be shaped so as to take into account the non-linearity or '' rotation '' of the load movement.

The load return movement to the rest position in the hose load 15 of Figure 2 may be effected by gravity or, if necessary, by return springs (not shown).

The load member 4 can also be used to adjust the inclination of the shoe element 3 with respect to a straight line parallel to the center axis of the roll • 20 or "tilts", which can influence the pressure curve at nipple N.

i ''; Figure 3 shows a shoe element according to another embodiment. 3 installation where principle and business opportunities are the same. Here: v. however, the loading hose has been replaced by a row of pressure fluid-driven cylinders extending across the machine, which forms a load-bearing ** '' loading member 4. A pressure medium, preferably a pressurized fluid having a certain pressure p and correspondingly, is supplied to the cylinders. the force F applied to the shoe element 3 and thereby the nip pressure in the nip.

! · ': 30

. ··. The position of the pressing device shown in Figures 2 and 3 is such that the web W

enters the nipple on the P side of the pivot. However, it is possible that the load mechanism formed by the shoe element 3 and the support plate 5 is located mirror-symmetrically, i.e. the pivot point P is on the outlet side of the web.

35 8 114031

Fig. 4 is a side elevational view of a shoe element assembly according to a third embodiment. The load members 4 acting between the shoe element 3 and the support element E are more than one in the machine direction (in the movement direction of the sheath 1a), 5 at different distances from the pivot point P on the same side thereof. In Fig. 4, there are two such members 4, the force of which can be changed, in contact with the support plate 5. The pressures acting on the various loading members may be individually controlled. The load members 4 can then also perform various functions such that one adjusts the positioning (tilt) of the shoe element 10 or fine-tunes the load. In Fig. 4, the loading members 4 are expandable loading hoses located in the transverse direction of the machine and containing pressure medium, preferably fluid. The force is adjusted according to the principle described above. One of the load members 4 may also be a series of hydraulic cylinders 15 according to the principle of Figure 3. This alternative is illustrated in Figure 5. It is also possible that both loading members 4 consist of a series of hydraulic cylinders. There may also be more than two loading members at different positions in the machine direction (N in the longitudinal direction).

20

The shoe element 3 preferably has a continuous support surface and has no static oil pocket or pressure pocket on its outer surface. Lubricating oil can be. ···. feeds the support surface of the shoe element 3 from the leading edge of the shoe element 3 and: v. between sheath 1a, as illustrated by arrow L in Figures 2 and 3.

However, it is also within the scope of the invention that the lubricating oil is introduced through bores introduced through the shoe element which open into a pocket formed on a support surface guiding the sheath 1a of the shoe element 3.

V. 30 All of the above shape options have front and back edges of the shoe element. '··. chamfered or rounded, whereby the chamfered or rounded portions are not intended to be nipple contact support surfaces, but to ensure trouble-free slip: 1a on and off the support surface of the shoe element.

35 9 114031

The support surface of the shoe element 3 is part of an integral structure in the sense that it does not consist of discrete blocks in the machine direction that could be moved closer and further apart. The support surface rotates as a whole around said pivot point P.

The stiffness of the support plate 5 supporting the shoe element 3 can influence the uniform depression of the shoe element towards the nip. The plate 5 may be uniform in the transverse direction of the machine (in the direction of the roll axis) or connected in different transverse directions of the machine.

The invention is not limited to the order of the rolls shown in the figures. For example, it is possible that the roller 1 or the like with the shoe element is up and the thermal roller 2 is down.

The above flexible resilient element 1a is a roll jacket which is tubular 15 or tubular attached at its opposite ends at the ends rotating on the roll. The roll mantle is then significantly wider than the shoe element read into the static element through the loading devices so that it can be circular at its attachment points and pass along a nip line width defined by the shoe element support pin-i... However, it is possible that the flexible, elastic element is a belt instead of a roll which forms an endless belt loop, whereby the belt is passed over the shoe element 3. The supporting. ♦ · *. the flap E to which the shoe element 3 is fastened is then located inside the strap loop.

25 '· * In addition to the calender, the invention may be applied by a press section, subject to its specific requirements. By means of the press section, by means of a flexible tubular rotatable sleeve 1a and a shoe element 3 guiding it ..., a so-called press nip is formed. long nip structures in a known manner.

30 When the compression pressure is adjustable in a known manner by means of a loading member. 4, the solution can influence dewatering in the nip. Two press elements may also be passed through the nip in the form of a felt or belt wrapped around an endless loop of the corresponding press roll.

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Claims (17)

114031 A method for compressing a paper web (W), wherein the paper web (W) is guided through a nip (N) formed between a movable element (1a) forming a flexible endless structure and a backing roll (2) of which the movable element is a flexible sheath. or a belt loop, wherein the movable element (1a) is supported in the area of the nip (N) against the counter roll (2) by a shoe element (3) defining a nip shape, characterized in that the shoe element (3) is supported at one point from a second point at a point from the pivot point to a loading member (4) which forces the load of the shoe element (3) and the corresponding pressure (p) on the nip and the movement of the shoe element (3) as the pivot point (P). Method according to Claim 1, characterized in that the loading force is applied by a tubular loading member (4) through the pressure of the pressure medium inside it. Method according to Claim 1, characterized in that the load force 20 is applied by the power generating actuators which are: arranged in a row and together forming a loading member (4). ίν, Method according to one of the preceding claims, characterized in that the load is applied by two or more load members (4) at different distances from the pivot point (P). A method according to any one of the preceding claims, characterized in that one or more loading members (4) adjust the position of the shoe element (3), i.e. the "bridge". ; · · 30 6. A method according to any one of the preceding claims, characterized in that the load or position adjustment is caused by a monochrome lever in which the shoe element (3) is located and whose pivot point (4) is. 35 114031 A paper web clamping device having a movable element (1a) having a flexible endless structure and a counter roll (2), the inside of the movable element (1a) having a shoe element (3) arranged to support the movable element (1a) against the counter roll (2). to form a pin (N), characterized in that the shoe element is supported at one point on a fixed pivot point (P) and in a machine direction at another point away from the pivot point on a loading member (4) arranged to cause the shoe element to . Pressing device according to Claim 7, characterized in that the loading member (4) is a tubular loading member which extends in the transverse direction of the machine. 15 Pressing device according to Claim 7, characterized in that the loading member (4) is a row of actuators located in the transverse direction of the machine. Pressing device according to Claim 9, characterized in that; ·, The actuators are hydraulic cylinders. * ► Pressing device according to one of the preceding claims 7 to 10, characterized in that there are two or more different loading members (4): at a distance from the pivot point (P). Pressing device according to one of the preceding claims 7 to 11, characterized in that the shoe element (3) is attached to a support plate (5) on which the loading member (4) is arranged on its opposite side and has an edge; 30 pivotable by said pivot point (P). Device according to one of the preceding claims 7 to 12, characterized in that the counter roll (2) has a harder surface than the movable element (1a). Device according to one of the preceding claims 7 to 13, characterized in that it is a calender. 114031 Device according to Claim 14, characterized in that the counter roll (2) is a heated thermal roll. Device according to Claim 14 or 15, characterized in that the movable element (1a) forming the endless structure is a roll casing of a calender roll. Device according to one of the preceding claims 7 to 13, characterized in that it is a press for removing water by pressing from a paper web. I »· •» · • 0 I · »• ·» · • I · • · »» · • · 13 114031