Method and apparatus in a paper or board machine for confining pulp flow from the headbox   

The invention relates to a method according to the preamble of claim 1 in a paper or board machine for confining a pulp flow coming from the headbox, in which by at least one deckle part being above the wire in the operating position the pulp flow coming from the headbox is confined in the lateral direction in the edge area of the wire.

The invention also relates to an apparatus according to the preamble of claim 11 in a paper or board machine for confining a pulp flow coming from the headbox, which apparatus comprises at least one deckle part being above the wire which in the operating position is arranged to confine the pulp flow coming from the headbox in the lateral direction in the edge area of the wire.

The apparatus being the object of the invention is typically referred to as a deckle. Its function is to confine the flow of stock discharged from a slice of the headbox onto the wire in the lateral direction on the edges of the wire. The aim is thus to prevent the uncontrolled spreading of stock onto the wire immediately after the headbox. After the stock has advanced through some distance on the wire in the machine direction and a sufficient volume of water has been removed from it, this problem disappears. A common way to confine the stock flow in the lateral direction is thus to use deckles on the edges of the wire immediately after the headbox. A deckle apparatus is described in FI patent specification 116796B. Another known arrangement is described in FI patent specification 115473B. A problem of known prior-art arrangements is, inter alia, that the sealing effect and the lubrication properties of the deckle have proven deficient in practice and this has had an impact on the pulp as susceptibility to the formation of undulations, among others.

The object of this invention is to further develop the arrangements of known prior art and to achieve a totally novel solution by means of which the problems of known prior art are avoided. The object of the invention is thus to provide an arrangement by means of which the sealing and lubrication of the deckle can be improved from earlier and thus to minimise the susceptibility to the formation of undulations.

The method according to the invention is mainly characterised in that, in the method, by a support part impervious to liquid being below the wire together with a deckle into connection with which liquid is brought, a pressure effect is provided which furthers the sealing between the deckle board and the wire and intensifies the lubrication of at least one sealing surface of the deckle.

In addition, the method according to the invention is characterised by what is stated in claims 2-10.

The apparatus according to the invention is mainly characterised by a combination which comprises a support part impervious to liquid being below the wire and a deckle part into connection with which liquid is brought such that a pressure effect is provided which furthers the sealing between the deckle board and the wire and intensifies the lubrication of at least one sealing surface of the deckle.

The apparatus according to the invention is further characterised by what is stated in claims 12-28.

The arrangement according to the invention has numerous significant advantages. By the support part impervious to liquid being below the wire together with the deckle into connection with which liquid is brought, a pressure effect is provided which furthers the sealing between the deckle board and the wire and intensifies the lubrication of at least one sealing surface of the deckle. Then, it has been possible to reduce or even completely prevent the formation of edge undulations and to reduce the range of basis weight variation in the edge area of the machine. Correspondingly, it has been possible to make the width of the edge area of reduced basis weight narrower. The runnability of the machine is improved and the width of the pulp web can be increased, whereby productivity is improved. The mechanical adjustments of the deckle do not change in connection with maintenance and wire change situations. The number of adjustment points has been substantially reduced, whereby the number of adjustments to be carried out by personnel is minimised. The arrangement enables an automation system to control the flow volumes of water in connection with the deckle on a quality-specific basis in accordance with speed. The fastening of the apparatus in the headbox is easy and it can also be automated. The deckle is easy to detach during a wire change from the tending side of the machine. The structure permits different water supply requirements at different points of the deckle. The structure of the deckle is sturdy. The deckle remains straight and does not get twisted and/or curved.

Next, the invention will be described in detail by means of an example with reference to the accompanying drawing in which

FIG. 1 shows a side view of an apparatus according to the invention,

FIG. 2 shows a top view of the apparatus of FIG. 1,

FIG. 3 shows a magnified view of section B-B of FIG. 1,

FIG. 4 shows a magnified view of detail A of FIG. 1,

FIG. 5 shows a magnified view of detail D of FIG. 2, and

FIG. 6 shows a magnified view of detail of FIG. 3.

FIGS. 1 and 2 show an apparatus according to the invention in connection with the forming section of a paper machine. The figure shows only one deckle. Typically, the forming section is provided with two deckles, one in or in the vicinity of each edge area of the wire of the forming section. FIG. 6 illustrates the invention in more detail.

The invention thus relates to a method and an apparatus in a paper or board machine for confining a pulp flow coming from the headbox 1, which apparatus comprises at least one deckle part 2 being above the wire which in the operating position is arranged to confine the pulp flow coming from the headbox in the lateral direction in the edge area of the wire 3. The invention is characterised by a combination which comprises a support part 50 impervious to liquid being below the wire 3 and a deckle part 2 into connection with which liquid is brought such that a pressure effect is provided which furthers the sealing between the deckle board 2 and the wire 3 and intensifies the lubrication of at least one sealing surface of the deckle 2.

The support part 50 is arranged below the wire 3 substantially at the point of the deckle 2 being above the wire 3. In the operating position, a surface of the support part 50 on the side of the wire is substantially in contact with the lower surface of the wire 3. The support part 50 is a substantially machine-directional (MD) strip part.

The apparatus further comprises means for supplying water when required between the deckle i.e. deckle part 2 and the wire 3. On the surface of the deckle part 2 on the side of the wire 3 is formed at least one first longitudinal groove 17 in which is advantageously arranged a liquid passage 17′ from the water supply means for supplying water. The first groove with its water supply functions, inter alia, as a sealing element.

On the surface of the deckle part 2 on the side of the wire 3 can also have been formed a second longitudinal groove which is closer to the edge of the wire 3 than the first groove 17. The groove typically functions, inter alia, as the collector groove of leakage pulp and leakage water, whereby the pulp and leakage water carried in it move along the wire away from the area of the forming device.

The support part 50 ensures and intensifies the sealing effect, inter alia, by decreasing the passage of liquid through the wire 3 in the area of the deckle 2. At the same time, it ensures the effectiveness of the lubrication of parts between the deckle and the wire. Furthermore, by means of it, it is possible to intensify the conveyance of leakage pulp and leakage water between the groove 17 and the wire away from the area of the forming device. The pressure effect provided by the support part 50 effectively prevents the passage of liquid and possible pulp fibres through the wire at the point of the deckle.

Between the deckle 2 and the wire 3 is brought water from openings 17′ arranged in the deckle. Liquid can be sprayed also with at least one spraying head 57 in a gap 53 between the deckle 2 and the wire.

Between the deckle 2 and the wire 3 is brought water from the openings 17′ arranged in the deckle, whereby water is supplied at an angle α (alpha) from a perpendicular direction in relation to the plane of the wire 3 inclined in the travel direction of the wire. The angle can be in the range of 0-90 degrees, advantageously e.g. 30-60 degrees. Water is supplied in at least one groove 17, 18 formed in the deckle 2, opening on the side of the wire 3.

The deckle 2 comprises one or more seal parts 52, 54 between which there is a gap or a groove 17 in which liquid is brought.

The support part 50 is mainly planar on the side of the wire.

The support part 50 is supported on a fastening surface 55 formed in a dewatering strip 51.

The invention relates to an apparatus in a paper or board machine for confining a pulp flow coming from the headbox 1, which apparatus comprises at least one deckle part 2 being above the wire which in the operating position is arranged to confine the pulp flow coming from the headbox in the lateral direction in the edge area of the wire 3. The invention is known by a combination which comprises a support part 50 impervious to liquid being below the wire 3 and a deckle part 2 into connection with which liquid is brought such that a pressure effect is provided which furthers the sealing between the deckle board 2 and the wire 3 and intensifies the lubrication of at least one sealing surface of the deckle 2.

The support part 50 is arranged below the wire 3 substantially at the point of the deckle 2 being above the wire 3. The support part 50 is a substantially machine-directional (MD) strip part. In the deckle 2 are arranged openings 17′ from which water is brought between the deckle 2 and the wire 3.

In the deckle 2 are arranged the openings 17′ which are directed to spray water between the deckle 2 and the wire 3 at an angle α (alpha) from a perpendicular direction in relation to the plane of the wire 3 inclined in the travel direction of the wire.

In the apparatus, water is supplied in at least one groove 17 formed in the deckle 2, opening on the side of the wire 3. The deckle 2 typically comprises one or more seal parts 52, 54 between which there is a gap or a groove 17 in which liquid is brought.

According to an advantageous embodiment, the surface of the deckle part 2 on the side of the wire 3 is formed oblique, whereby between the wire 3 and the deckle part there is on the side of the edge of the wire a gap 53 which narrows in the cross machine direction at least towards one seal part 54. The apparatus comprises at least one spray nozzle 57 for spraying liquid in the gap 53 between the deckle part 2 and the wire. In accordance to an advantageous embodiment of the arrangement according to the invention, water can be sprayed with the nozzle 57 which is directed to spray towards the gap 53 between the wire 3 and the deckle 2. There can be nozzles 57 at suitable intervals divided on the length of the deckle 2. Correspondingly, there are openings inside the deckle arranged dividedly on the length of the deckle according to the target of application.

In the embodiment of the figures, the deckle i.e. deckle part 2 is arranged to be movably supported in the longitudinal machine direction and the deckle part 2 further comprises a fastening point 21 at which the deckle part 2 is fastened in the operating position substantially immovable at least in the longitudinal direction of the machine. According to an advantageous embodiment, the fastening point 21 of the deckle part 2 is at or in the vicinity of the end on the side of the headbox 1. The fastening point can thus also be located in a support structure 1′ on the side of the headbox. The support elements of the deckle comprise a support body 4 in which the deckle part 2 is arranged to be movably supported, particularly slidingly supported, in the longitudinal machine direction. Typically, in the deckle part is arranged e.g. a groove 15, such as a dovetail groove, in which a counter part 16 of the support element 4 is arranged to fit. Naturally, the groove and the counter part can also exist the other way around, whereby the groove is in the support element and the counter part in the deckle part. In the embodiment of the figure, the deckle part 2 is supported by a side wall 2′ facing away from the pulp web.

The support body 4 of the deckle is arranged movable between at least two positions, a first position i.e. operating position in which position the deckle confines the pulp flow in the lateral direction, and a second position i.e. maintenance position in which position the deckle has been moved upwards at least to a distance from the surface of the wire 3. The figures show the deckle in the operating position. The support body 4 is arranged to be movable by at least one actuator 9 between the first position and the second position.

The moving devices of the support body 4 typically comprise a support part 5 which is arranged in a support structure 6 or equivalent of the machine, and a first support arm 7 which is rotatably arranged in the support part around an axis 8 crosswise in the machine direction, and further an actuator 9 which is arranged to move the support arm 7, in which support arm the support body 4 is arranged to be rotatable around a second crosswise axis 10. This arrangement allows the motion of the deckle part away from the headbox and upwards from the plane of the wire when being moved to the second position. In the second position, the deckle part 2 has thus been moved in the machine direction away from the headbox 1 and upwards from the plane of the wire 3.

The moving devices of the support body 4 comprise at least one adjustable stopper part 12 and a stop surface 13 for it, against which stopper the stop surface sets at least in the operating position. In the embodiment of FIG. 4, the stopper part 12 is a screw part.

The fastening point 21 of the deckle part 2 advantageously comprises a form-locking joint 22, 23 for locking the deckle part also in the cross direction.

Typically, there are thus on each side of the machine two deckle mechanisms operating independently on the fourdinier wire of the forming section. The figure shows part of the headbox diagrammatically. Of the forming section, FIGS. 1, 2, 3 show some dewatering elements over which the wire 3 runs. The deckle part 2 of the deckle is most suitably fastened in the actuator only at the end on the side of the headbox 1, whereby the longitudinal motion of the machine and variations in the distribution of temperature along the length of the deckle have no effect on the deformation of the deckle, but the deckle is able to move freely in the machine direction on the support in the longitudinal machine direction. The longitudinal support of the deckle in the elevation of the deckle is arranged such that the deckle cannot be twisted around the centre of its cross profile and then the edge of the web being screened remains stable in the vertical direction.

The deckle 2 is slidably supported in its support elements 4 typically substantially for the entire length of the deckle 2. The support element 4 is fastened on the side walls of the headbox 1 or some other support element 1′ typically by only one fastening in the longitudinal machine direction. The fastening can easily be changed into an automatically operated locking. In the embodiment of the figures, the lock is e.g. an eyebolt which the operator opens into the open position before maintenance operations.

In the arrangement according to the invention, the basic settings of the deckle 2 at the end on the side of the headbox undergo no change after a wire change and a washing shutdown, but the end of the deckle always assumes the same position in relation to the headbox 1. The support of the deckle at the end of the headbox only allows vertical motion for adjusting the gap between the deckle and the wire. In the preassembly, the deckle is set in a known manner in relation to the side wall of the headbox, and there is no need to change this adjustment during operation. Only a vertical adjustment parameter is determined during the run event. For the duration of the adjustment event, the locking of the headbox is loosened and the adjustment is made at the point of the first support element. The locking on the side of the headbox also allows the toe-in of the deckle 2 to change in relation to the web (positive toe-in), whereby the deckle moves away from the web in the travel direction of the web or alternatively approaches the web if the toe-in is negative. In a maintenance situation, the fastening of the headbox also allows the deckle mechanism to move away and simultaneous vertical motion, advantageously rotational motion, away from the headbox and, correspondingly in a closing situation when in the lower position, the deckle assumes its position corresponding to the starting situation and is locked in place in the longitudinal machine direction. The control mechanism is advantageously a wedge coupling being wedge-shaped or having a surface of revolution, which guides the parts against each other in the cross and longitudinal machine direction, while the vertical direction is free and locked by a frictional locking after the maintenance operation.

The support body 4 is advantageously a relatively rigid profiled beam, advantageously a tubular beam, having a length at least substantially equal to that of the deckle part 2, sliding fastening 15, 16 of the deckle 2 being located on a side surface of the beam. The support body receives the pressure and flow force components produced by the pulp web. The support body, advantageously its beam structure, retains its direction and does not bend laterally or vertically contrary to the process values. The support body 4 can be arranged or it can form a channel or several channels for conveying lubrication and sealing water to the deckle 2. In the support body, there can be externally fastened one or more lubrication, sealing or boundary lubrication water lines 30, and likewise an external spraying nozzle 31, by means of which desired mediums, particularly liquid mediums, can be applied over the length of the deckle 2, most suitably by zones.

The adjustments of the support body 4 are implemented in a space between the support body 4 and the support structure of the wire, such as a body beam 6. As is known, on the body beam 6 of the wire there is a fastening surface for dewatering elements, and the moving and adjustment apparatus of the deckle can be supported on the same fastening surface. The adjusting device comprises a moving mechanism, advantageously a lever mechanism 7, 8, 9, 10, by means of which the support body 4 and the deckle part 2 are lifted and moved aside from the fastening of the headbox and the surface of the wire 3. The upward motion of the lever mechanism 7 and the distance of the deckle from the surface of the wire are limited by a stopper/adjuster 12, 13, suitably adjusting/locking screws. The deckle can be adjusted in a known manner to a somewhat different distance from the surface of the wire according to the travel direction of the web such that the trailing end of the deckle is higher than the end on the side of the headbox. It is also possible that the deckle 2 is at a constant distance from the surface of the wire, depending on the other run parameters of the machine. The deckle part can be easily lifted to a maintenance position. This can be done particularly during the washing of the deckle and the wire change. For the time of the wire change, the support body of the deckle can be very easily detached from the lever mechanism from the tending side of the machine and lifted onto the machine aisle by means of an overhead crane. The lifting points are located in an advantageous place in the structure and the rigidity of the structure is such that the lifting event will not harm the deckle itself in any way, which is a problem of known fastening mechanisms. When remounted, the parts assume the same positions from which they were detached, whereby changes in personnel will not change the adjustments. The deckle adjustments are only influenced by changes in water flow in the process which can be determined quality-specifically for each quality. This has not been possible to implement earlier with the obsolete deckle structure.

There is no need to detach the support and adjustment mechanisms above the body 6 of the wire, and the deckle on the tending side of the machine need not be detached in any way from the support structure. On the operating side of the machine, only the fastening of the headbox is detached and the deckle is lifted up automatically. The moving mechanism also includes an actuator 9, in the embodiment of the figure bellows (in FIGS. 1 and 2 three bellows on either side of the machine). The actuator 9 can be any pressure-medium operated device or electric device. The structure typically requires at least one actuator 9 on either side of the machine. Depending on the length of the support structure 4, there are at least two support points on either side of the machine. The position of the forward end of the deckle 2 in relation to the surface of the wire 3 is adjusted by means of the support structure on the side of the headbox 1. In the support structure, there also is depth adjustment, by means of which the distance of the deckle is adjusted in relation to the centre line of the machine, either straight or toe-in. After basic adjustments, the machine personnel will not touch the settings, only the water flow 35 values are changed.

The device according to the invention can be used in connection with an automatic control system (not shown in the figure). Then, the structure includes local control boxes on the tending and operating side of the machine, not shown in the figure. Furthermore, the automation system of the machine contains quality-specific run parameters for the water supplies of the deckle.

It is obvious to those skilled in the art that the invention is not limited to the embodiments described above, but it may be varied within the scope of the enclosed claims. When necessary, the features possibly described in this specification together with other features may also be used separately from each other.