Patent Description:
Prior art sleeve rolls are for instance known from document <CIT>. Here, a sleeve arrangement with stationary sector support shoe/beam is arranged in a forming section of a paper or board making machine. The forming section comprises two wires, each of them forming a closed loop. The two wires are guided such that they run along a portion of the sleeve arrangement with a stationary sector support shoe/beam circumference in an adjacent manner, thereby forming a fabric wrap where web is sandwiched between the wire. Thus, the sleeve arrangement with a stationary sector support shoe/beam causes a minimum distance between the two wires, thereby causing dewatering of a web located between the two wires.

Another forming section similar to the one of <CIT>, but comprising a sleeve roll with a cross section having a changing radius of curvature is known from document <CIT>. This shape enables an improved dewatering pressure caused by the change of the sleeve roll's radius of curvature.

<CIT> discloses a forming roll in a forming section of a paper making machine. The forming roll has a support ledge and having a radius getting smaller in running direction.

<CIT> discloses a forming roll corresponding to that of <CIT> and a shoe roll in the same fabric loop of a tissue paper making machine. A small size axle beam supporting the sleeve roll corresponds to that of the shoe roll. The axle beam is designed for a nip load acting in one direction. There is a shoe roll nip formed between the shoe roll and a yankee cylinder.

<CIT> discloses an apparatus for protecting a jacket in a hot shoe press roll nip. In the show roll, double acting cylinders are applied.

<CIT> discloses a press with an extended nip for a paper or board making machine. The nip is formed by means of a press shoe.

In general, a sleeve roll comprises a static portion such as an axle beam for supporting a belt rotating about the axle beam. The belt is driven by the wire running about a portion of the sleeve roll sliding surface. Thus, there arise problems with friction forces, in particular during start up, where static friction forces occur, in a slow running mode where static friction forces as well as sliding friction forces occur, and in a normal running mode where mainly sliding friction forces occur.

There is need for a sleeve roll capable of coping with friction forces in different running modes.

According to the invention, a sleeve roll comprises an axle beam with an axle stub. The axle stub is supported in a bearing structure. Moreover, the sleeve roll comprises a roll head, which is configured to support a belt tensioned about and being rotatable about the axle beam in a belt loop. The belt is rotatable about and relative to the axle beam. A movable forming element is configured to protrude from the axle beam, thereby abutting against the belt to vary a cross sectional shape of the belt loop. The movable forming element is supported at the axle beam, the support being a hinge.

Thus, by means of the movable forming element the shape of the belt loop running about the axle beam and corresponding to the circumference of the roll head can be changed to have a protrusion where the movable forming element protrudes. This protrusion can be effected even during the paper or board making machine is running. Accordingly, a start moment can be reduced, when the movable forming element is retracted while starting, and effecting the protrusion only after the start has been performed. During start up of the fiber web forming machine, the forming element is retracted inside the belt circle and support behind the element is against the belt inner surface. During start up all the lubrication inlets for sliding surface are in use and the wire tension can be reduced. Additionally, control of the water removal peak pressure and of the fabric tension is possible. The latter allows control of the water removal profile.

Moreover, such a movable forming element can be replaced easily when it is worn or when a radius of the surface abutting against the belt is to be changed. Advantageously, a sliding surface can be arranged adjacent to and, in a rotating direction of the belt, before the movable forming element.

Advantageously, the movable forming element can be movable forwards and backwards in a protruding direction.

Thereby, the movable forming element can take at least two positions, that is, retracted or protruding.

Advantageously, the forwards and backwards movement of the movable forming element in the protruding direction can be effected by means of a piston accommodated in a cylinder. The piston is capable of acting in both directions.

Such an arrangement effects that the movable forming element can be set at an arbitrary protruding position within the stroke of the piston. Thereby, when providing adjacent movable forming elements in the axial direction, any deflection can be compensated within a minimum range. With other words, the bending line in the cross machine direction (of a paper or board making machine) can be set to vary from an intended bending line less than <NUM>/m.

The movable forming element is supported at the axle beam, the support being a hinge and, advantageously, the forming element moving cylinder structure is hinged.

Thus, the forces of the rotation of the belt and tension from the wires wrapping partially the sleeve roll acting on the movable forming element are transferred to the axle beam having a rigid structure without affecting the accuracy in the web forming process. In a case where the movable forming element is supported by a hinge, instead of the above linear protrusion and retraction movement, the protrusion and retraction movement is performed along a curve. Thereby, in combination with a correspondingly changing radius of the top surface of the movable forming element getting into abutment with the belt, a smooth adjustment of the protrusion height while maintaining a low friction between the top surface of the movable forming element and the belt is achieved.

Protrusion of the forming element affects to the belt when exceeding the sleeve roll radius in operation position. Thus, good lubrication must be arranged before the forming element to ensure smooth belt gliding over said element which tensions the belt outwards. During the start up the forming element can be retracted inside the roll head circle to reduce friction.

Protrusion/outstroke of the forming element out of the roll head/ belt circle can be <NUM>-<NUM> advantageously <NUM>-<NUM>. Also belt indent/inwards bulging before the forming element is possible while the sliding surface can be arranged some (tens) of millimeters below the head/belt but on the same radius. This helps to reduce the required protrusion/outstroke of the forming element, which is favorable to the life of the belt when reducing the belt tension, and thereby the belt wear.

Thus, remarkable changes of the fabric tension wrap parameters are possible. On the other side, too high forces acting onto the belt from the movable forming element, as well as bending forces acting on the support of the movable forming element due to friction between the belt and the top surface of the movable forming element can be prevented.

Advantageously, in cross section, a surface of the forming element abutting against the belt can have a curved, convex shape.

Thereby, a change of the curvature of the top surface of the forming element abutting against the belt can be applied. Thus, a compensation of the roll deflection can also be performed this way.

Advantageously, a radius of curvature of the curved, convex shape of the surface of the forming element abutting against the belt can get smaller in the rotating direction of the belt.

Thereby, the wire tension profile can be controlled in a smooth manner. Moreover, bending of the sleeve roll can be compensated.

Advantageously, a radius of curvature of the curved shape of the surface of the forming element abutting against the belt can change continuously or stepwise, wherein a number of steps can be <NUM> to <NUM>.

Since the movable forming element can be easily replaced, it is possible to apply different movable forming elements with dedicated top surface shapes in dependency of the paper or board making process. A material of the forming element can be metal or polymer (reinforced composite) or a combination thereof. A manufacturing method can be extrusion, machining, additive manufacturing or casting. Also low friction coating or surface hardening can be used for the sliding surface and / or a forming element prone to wear.

Advantageously, the sliding surface can cover a sector of <NUM>° to <NUM>° of the sleeve roll.

Since this range almost corresponds to the wire wrap, friction caused by the wire acting on the belt can be remarkably reduced. Moreover, it is possible to add another sliding surface in the belt running direction after the movable forming element to support the belt and reduce friction in a case where the movable forming element is retracted, for example during start up of the fiber web forming machine.

Advantageously, the sliding surface in a cross section can have the same/constant radius of curvature than the roll head.

Advantageously, a sliding surface of the sliding element can be surface treated and/or can have depressions. Moreover, lubricating means can be arranged before the sliding surface in a rotation direction of the belt, and/or through the sliding surface. These dimples/recesses/pockets are extended in the length direction of the axle beam as discrete row/s. There are narrow land areas between said pockets filled with lubricating oil. Recesses can have different lengths and different numbers of oil inlet openings per recess.

Thereby, the coefficient of friction is further reduced.

The invention also pertains to a paper or board making machine, which, in a dewatering section or forming section comprises two wires and the sleeve roll as described above. The wire on the side of the sleeve roll is in abutment with the sleeve roll at the sliding surface, thereby transferring a rotation force to the belt of the sleeve roll.

In the following, presently preferred embodiments of the invention will be described based on the figures, in which.

An example of a schematic structure of a forming section <NUM> of a paper or board making machine applying a sleeve roll <NUM> according to the invention is shown in <FIG>. A head box <NUM> serves to supply a pulp suspension between the wires <NUM>, <NUM> which are guided as closed loops. The wire loop <NUM> is guided by guiding rolls <NUM>, a forming roll <NUM> and the sleeve roll <NUM>. A second wire <NUM> is guided in another closed loop by guiding rolls <NUM>, the forming roll <NUM> and the sleeve roll <NUM>. Between the forming roll <NUM> and a guiding roll 1007a of the guiding rolls <NUM> dedicated to the second wire <NUM>, both wires <NUM> and <NUM> run in a parallel manner sandwiching the thereby formed web.

A forming gap with constant radius fabric tension wrap on forming roll and changing radius fabric tension wrap on sleeve roll is formed between the two wires <NUM> and <NUM> at circumferential portions of each of the forming roll <NUM> and the sleeve roll <NUM> where both wires <NUM> and <NUM> run along the circumferential portions of the two rolls. Due to a slight elongation of the wires <NUM> and <NUM> in the portions not affected by a roll, in these fabric tension wrapsa pressure acting through wire tension on the web is higher than in the portions where the wires are not supported.

The forming gap and fabric tension wrap formed at the forming roll <NUM> serves to receive the pulp suspension from the headbox <NUM>. To provide this tension wrap at the forming roll <NUM>, the second wire is guided towards the forming roll by means of a breast roll 1007b, which is arranged close to the forming roll <NUM> in a manner that a diffusor portion of the headbox <NUM> is arranged between the forming roll <NUM> and the breast roll1007b. Thus, a first dewatering of the web is performed at the forming roll <NUM>.

Another fabric forming wrap is formed at the sleeve roll <NUM>. Since this description is mainly directed to the sleeve roll <NUM>, in the following the fabric forming wrapformed at the sleeve roll <NUM> will be described as "the fabric forming wrap" while, if necessary, the fabric nip formed at the forming roll <NUM> will be described as "the constant radius fabric tension wrap" or simply as "fabric tension wrap" (at the forming roll <NUM>).

Moreover, in the forming section other means for dewatering of the web such as dewatering elements <NUM> or suction boxes <NUM> are arranged. It will be understood that the above description of the forming section based on <FIG> is merely an example and does not at all limit the forming section to the wire arrangement and elements shown in <FIG> and described above. That is, next to the described elements or additional dewatering elements and suction boxes can be provided. On the other side, one or more of the shown dewatering elements and/or suction boxes can be omitted. Moreover different types of web forming concepts being suitable for all types of formers, head boxes, layouts and webs can be chosen. Likewise the function of the sleeve roll and its place within the former can vary according to specific needs of the particular web to be formed.

In order to form a web, pulp suspension is supplied from the headbox <NUM> into the forming gap and the constant radius fabric tension wrap at the forming roll <NUM> where a first dewatering takes place. From there, the web is guided between the two wires <NUM> and <NUM> towards the sleeve roll <NUM> and the fabric tension wrap. Thereby, the web passes dewatering means <NUM>, which improves the dryness content of the web. In the fabric tension wrap, a second dewatering takes place. As will be described below, by means of the sleeve roll <NUM> according to the invention, parameters of the fabric tension wrap such as its length, its exerted pressure, the running time of the web to pass the fabric tension wrap and others can be set. Thus, an effective dewatering takes place before the web is guided further via suction boxes <NUM> to be taken over to be transferred to the next section such as a press section of the fiber web forming machine.

A sleeve roll <NUM> according to the invention comprises an axle beam <NUM> and an axle stub <NUM>. As can be seen from <FIG>, the axle stub <NUM> is supported in a pedestal (example for a bearing structure) <NUM>. Moreover, as can be seen from <FIG>, the sleeve roll <NUM> comprises a roll head <NUM> that supports a belt <NUM>. The belt <NUM> is tensioned about and is rotatable about and relative to the axle beam <NUM>. In particular, rotation of the belt <NUM> is caused by the wire <NUM> directly contacting the belt <NUM> due to wire tension during the common path when passing the sleeve roll <NUM>.

Back to <FIG>, the pedestal <NUM> comprises an annular flange <NUM> mounted onto the axle stub <NUM> in such a manner that a torque can be transferred from the flange <NUM> to the axle stub <NUM>.

In order to provide a torque, the flange <NUM> is connected with a rigging screw <NUM> by means of a joint <NUM>. That is, one end of the rigging screw <NUM> is attached to the flange <NUM> by means of the joint <NUM>. The other end of the rigging screw <NUM> opposite to the one end being attached to the joint is fixed to the pedestal <NUM>. Thus, by turning the rigging screw <NUM>, it length can be extended or shortened, thereby causing a rotation of the flange <NUM>. The rotation of the flange <NUM> is transferred to the axle stub <NUM>, thereby rotating the axle stub and the axle beam <NUM> of the sleeve roll <NUM>. The flange <NUM> and the joint <NUM> form a moving means according to the invention, and the rigging screw <NUM> is one example of an actuating means according to the invention.

That is, instead of the rigging screw, the actuating means can comprise a screw, a gear, a worm gear, a hydraulic cylinder or other means suitable for providing a longitudinal movement which is then transferred to the rotational movement of the flange <NUM>.

As can be seen from <FIG>, the axle beam <NUM> is made of a hollow polygonal structure with (in the embodiment, eight) rounded corners. Moreover, a cross section of the axle beam body <NUM> is symmetric in different planes, and the width (in a y-direction in the figures) of the axle beam <NUM> is larger than its height (in a z-direction in the figures). The thickness of the plates forming the axle beam body <NUM> is between <NUM> and <NUM>. This geometry of the axle beam effects outstanding rigidity in its axial direction (rotation axis A direction), while forming of the desired cross sectional shape is still possible.

Rounded corners in the sense of the invention is to be understood that the corners have an arc like, convex, curved portion having a certain radius of curvature.

A head portion <NUM> of the axle beam <NUM> has a flange like shape and is provided with plural mounting bores <NUM>. The head portion <NUM> is surrounded by an axle beam body <NUM> which is comprised of two bended metal sheets 111a, 111b. The two metal sheets 111a, 111b are welded together at their edges to form a hollow body. The edges are arranged in a parallel manner to a rotation axis A of the sleeve roll <NUM>.

Moreover, in the axle beam <NUM> a maintenance opening <NUM> and other openings are provided to enable access to the inner space of the axle beam <NUM>. Some or all of these openings can be closed with hatches.

As can be seen from <FIG>, the axle stub <NUM> is mounted to the head portion <NUM>. The roll head <NUM> is provided on the axle stub <NUM> in a sliding manner. Thus, the roll head <NUM> can move in an axial direction of the sleeve roll <NUM>. In order to effect such a movement of the roll head <NUM>, hydraulic cylinders (only one of them is shown in <FIG>) <NUM> are fixed inside of the axle beam. A piston rod of each hydraulic cylinder <NUM> extend through the head portion <NUM> of the axle beam <NUM> and is fixed to the roll head. Thus, the roll head <NUM> can be moved in a sliding manner in the direction of the rotation axis A, that is, in <FIG> to the left and to the right. Thereby, on the one side an axial position of the roll head <NUM> can be determined, and on the other side, the tension of a belt <NUM> fixed to the roll head <NUM> and surrounding the axle beam <NUM> can be adjusted. The plural hydraulic cylinders <NUM> are arranged in such a manner, that the belt <NUM> is tensioned by a symmetric tensioning force.

For accurately determining the roll head's <NUM> position, and/or to prevent an excessive stretching of the belt <NUM>, indexing means (not shown) are provided to inform a user of the roll head's amount of movement. In the embodiment, the indexing means show the distance from the inner side (right side in <FIG>) of the pedestal <NUM> to the roll head <NUM>.

Moreover in the roll head <NUM> an opening through the axle stub <NUM> is provided. The opening can be closed in an airtight manner and serves to arrange e.g. inlet and outlet pipes for fluids such as lubrication oil. Since the opening can be closed in an airtight manner, a pressure inside of the belt <NUM> can be maintained.

As shown in <FIG>, the axle beam has a sliding surface <NUM>. The sliding surface extends in a length direction and curves in a cross direction of the axle beam <NUM>. In the embodiment, the sliding surface is an individual component mounted to the axle beam <NUM>, but instead it can be integrally formed with the axle beam <NUM>.

Moreover, a movable forming element <NUM> is arranged adjacent to the sliding surface <NUM> in the axle beam body <NUM>. That is, the forming element is provided such that the belt <NUM> passing the sliding surface <NUM> thereafter goes over the forming element <NUM>. In cross section, a surface <NUM> of the forming element <NUM>, which is in abutment against the belt <NUM> has a curved, convex shape. A radius of curvature of the curved, convex shape of the surface <NUM> gets smaller in the rotating direction of the belt <NUM>. Said curvature of the forming element gets smaller in radius than the radius of the sleeve roll. The forming element is movable to that regard that its protruding height from the axle beam body <NUM> can be altered. In the axle beam body <NUM>, a piping system is provided to supply lubrication fluid to the sliding surface <NUM>.

Since the movable forming element <NUM> is configured to protrude from the axle beam <NUM>, it abuts against the belt <NUM> which is rotating about the axle beam <NUM>. By altering the forming element's <NUM> protrusion height, a cross sectional shape of the loop formed by the belt <NUM> is altered.

In order to protrude or to retract, the movable forming element <NUM> is made to move forwards and backwards in its protruding direction z. This is effected by means of a piston <NUM> accommodated in a cylinder <NUM>. The piston <NUM> is capable of acting in both directions. Thus, the movable forming element can be made to protrude a desired height. Protrusion of the forming element affects to the belt when exceeding the sleeve roll radius in the operation position. Thus, a good lubrication must be arranged before the forming element to ensure smooth belt gliding over said element tensioning the belt outwards. In the start up the forming element can be retracted inside of the roll head circle in order to reduce friction.

Protrusion/outstroke of the forming element out of the roll head/ belt circle (the imaginary shape of the section of the belt which is a circle, unless it is guided in a different manner) can be <NUM>-<NUM>, advantageously <NUM>-<NUM>. In <FIG> the belt circle is indicated with 41a and drawn with a dashed line. Also belt indent/inwards bulging before the forming element is possible while the sliding surface is arranged some (tens) of millimeters below the head/belt but at the same radius. This helps to reduce the required outstroke which favorable to the life of the belt.

The movable forming element <NUM> is supported at the axle beam <NUM> by means of a hinge <NUM>. Thus, the position of the movable forming element <NUM> cannot only be changed in a linear manner, but it can also be tilted. The moving means of the hinged forming element are favorably also tiltable/hinged.

In the running direction of the belt <NUM>, arranged before the movable forming element <NUM> is the sliding surface <NUM>. The sliding surface <NUM> in a cross section has the same radius of curvature than the sleeve roll/roll head <NUM>. Moreover, the sliding surface is surface treated and preferably can be provided with depressions such as dimples. In addition, lubricating means <NUM> are arranged before the sliding surface <NUM> in a rotation direction of the belt <NUM>. Thus, a coefficient of friction of the sliding surface <NUM> can be remarkably reduced, resulting in a smooth run of the belt <NUM> over the sliding surface <NUM> before it gets to the movable forming element <NUM>.

As will be understood, due to the movable forming element <NUM>, the cross section shape of the sleeve roll <NUM> can be altered depending on the requirements of the web being formed. Moreover, these alterations can be performed while the paper or board making machine is running. In addition, not only the cross section of the sleeve roll <NUM> can be altered, but by rotating the axle stub <NUM> via the rigging screw <NUM> and the flange <NUM>, the rotational position of the movable forming element can be changed. Thereby, it is possible to effect changes of the fabric tension wrap parameters in a high variety which leads to an improved dewatering and forming of the web. Reference signs <NUM> indicate additional sliding elements, one of them being provided close behind the movable forming element <NUM>.

In addition, <FIG> and <FIG> show pipes <NUM>, <NUM>, <NUM> used for supply and discharge of lubricant (see the arrows in the pipes in <FIG>). Supply and discharge is performed via bores in the axle stub <NUM>. Moreover, these pipes are supported in the inner of the axle beam <NUM>. A main discharge pipe <NUM> serves for return lubricant which needs to be cooled and filtered before being newly fed to the sleeve roll. In addition to the lubricant feed pipes smaller hydraulic pipes such as the ones referred to by <NUM>, 118a, 118b are also shown. These latter hydraulic pipes <NUM>, 118a, 118b serve for actuating the piston <NUM>. Connections to the hydraulic actuators, lubricant collector devices and lubricant feeding/spraying pipes are performed by means of steel enforced hoses for allowing thermal movements and bending.

While the invention has been described based on a presently preferred embodiment thereof, the scope of the invention is not limited by the above description and the figures, but is defined by the claims.

Accordingly, alterations to the embodiment are possible. For instance, the described cross sectional shape is not necessarily provided for the whole axle beam body, but merely a portion of the axle beam body can have a polygonal cross section. The other portion(s) can have a different cross section.

The polygonal cross section can have six to twelve corners or corresponding angles. While it is preferred that the corners are rounded, such rounding is not unambiguously necessary, for instance in a case where the metal sheets are not bended but plural metal stripes are welded together to form the axle beam body.

Also, at least one portion of the axle beam body can have a round cross section.

Instead of changing continuously, the radius of curvature of the curved shape of the surface of the forming element abutting against the belt can change stepwise. A number of steps can be <NUM> to <NUM>.

While a certain range of the wrap is not mentioned above, the sliding surface can cover a sector of <NUM>° to <NUM>° of the sleeve roll ,so that the wires having common wrap on the sleeve roll can drive the belt with help of the supporting sliding surface.

While in the embodiment lubricating means are arranged before the sliding surface in a rotation direction of the belt, lubricating means can alternatively or additionally be provided through the sliding surface. The arrangement of the lubrication means depends on the assembly before forming of the sliding surface.

Claim 1:
Sleeve roll (<NUM>) comprising
an axle beam (<NUM>) with an axle stub (<NUM>), said axle stub (<NUM>) being supported in a bearing structure (<NUM>);
a roll head (<NUM>) configured to support a belt (<NUM>) tensioned about and being rotatable about the axle beam (<NUM>) in a belt loop;
the belt (<NUM>) being rotatable about and relative to the axle beam (<NUM>); and
a movable forming element (<NUM>) configured to protrude from the axle beam (<NUM>), thereby abutting against the belt (<NUM>) to vary a cross sectional shape of the belt loop,
wherein
the movable forming element (<NUM>) is supported at the axle beam (<NUM>), characterised by the support being a hinge (<NUM>).