EP4283039A1 - Device for smoothing and applying an application medium - Google Patents

Abstract

Device for smoothing a paper or cardboard web (9) with at least one nip (6) which is formed between two rollers (3, 4), at least one of the rollers (3) being used to regulate a cross-thickness profile of the paper or cardboard web (9 ) in the transverse direction of the web, a deflection-adjustable and zone-controlled roller (3) is used to set a line load distribution that can be selected in at least one nip (6) over the roller width, whereby the at least one nip (6) is intended to use an adjustable line load profile to adjust the thickness cross profile of the paper or cardboard web (9) and at the same time introduce an application medium (2) into the paper or cardboard web (9), for which at least one application unit (1) with a delivery nozzle (8) for applying application medium (2), in particular starch, is arranged in this way that the application of the application medium (2) is provided on at least one of the two rollers (3, 4) of the nip (6) and designed for an indirect application of the application medium (2) on at least one side of the running paper or cardboard web (9). is, and the at least one applicator (1) has at least one dispensing nozzle (8) with a device (13) for adjusting the transverse profile of a volume flow of the application medium (2) which can be adjusted zone by zone over the web width.

Description

The invention relates to a device for smoothing with at least one nip which is formed between two rollers, at least one of the rollers being a deflection-adjustable and zone-controlled roller for regulating a thickness profile of a paper or cardboard web, according to the preamble of claim 1.

Out of WO2004/001132 A2 Machines are known that enable the production and treatment, including application of an application medium on at least one side of the material web in a so-called online or offline operation. For many applications, a material quality with high smoothness and possibly gloss is desired. In order to achieve such quality, the machine a material web smoothing device along the material web path at least in front of the application device. The pre-smoothing of the material web before the application of the application medium is particularly expedient and effective in that the contactless application process, in particular the brushing process, largely preserves the contour of the material web surface. This means that a rough contour of the material web is not, or only comparatively little, compensated for and thus smoothed by the application medium. The smoother the material web was before the application medium was applied, the higher the productivity achieved. In this context, it has been found that it is better to smooth first and then apply the contour stroke than to smooth a rough contour after painting. When it comes to applying the application medium, a so-called curtain application process (curtain coating) is preferably used.

The non-contact methods of applying the starch, for example curtain sizers and spray sizers, are from the scriptures EP 3 617 403 A1 and AT 519598 A2 , WO2020020626A1 known. In these processes, the application quantity is metered via a quantity control on the application nozzles themselves. Squeegee devices are not required here.

Out of EP 0 374 292 A1 Devices for smoothing and calibrating paper are known, which compress and smooth the paper. Fluctuations in the thickness of the paper are compensated for and the paper is calibrated. The result is a compacted paper with a leveled surface. This requires uneven density, reduced thickness, stiffness and opacity. In order to calibrate a paper, ie to give a paper an identical thickness in all places, the pressure given by the weight of the rollers of a calender is usually too low. The calender is therefore subjected to additional pressure. In order not to limit the flexibility of the system to a few basis weight-pressure pairings, one of the rollers is preferably designed as a zone-controlled deflection compensation roller, which replaces a rigid crowning.

Nowadays, paper manufacturers are often faced with the challenge of increasingly using recovered paper fibers in the production of paper, especially packaging paper and cardboard, as well as in specialty papers. In the EU, the testliner is mainly made from waste paper and fillers. Due to a high proportion of secondary fibers, the strength properties of the packaging papers decrease. The use of starch can compensate for the loss of strength in papermaking. The starch is usually either added directly to the pulp suspension or sprayed onto the wet web in the wire section. Furthermore, the starch can be applied to the paper web immediately after the pre-drying group using contact or non-contact application methods.

Testliner and folding box board can be coated several times. After pigmentation in the film press, a middle coat and a top coat are usually applied to the paper web using a blade coater. The subsequent coating process with a blade coater requires a smooth surface of the base paper (macro surface roughness Bendtsen < 500 ml/min, micro surface roughness PPS < 3µm) and a very uniform paper thickness (2sigma deviation < 1% - 1.5%). The paper thickness may only show slight deviations across the width of the paper web. That is why pre-smoothing is usually carried out with a calender or with the help of a Hartnip calender before coating, namely for pre-smoothing before coating and to calibrate the paper thickness. When smoothing testliner and folding box board on one side, only one nip is used. A calendering unit preferably consists of two rollers, in particular a heated steel or chilled cast iron roller and an unheated profiling roller. In most cases, thickness cross-section control is achieved with zone-controlled elements.

Size presses and film presses are known as contact application processes, for example in DE 3417487 A1 and DE 4131131 A1 described. The strength or

Glue suspension is applied to an applicator roller using a metering applicator and metered using a squeegee. The paper or cardboard web is coated on both sides in a press nip between the applicator rollers. The temperature of the starch is usually between 50°C and 80°C. The typical solids content of the starch is between 8% and 15% with an application weight of 0.5 to 6 g/m ² per side. In individual cases it is also possible with a film press of this type to apply the coating color consisting of starch and pigment particles with a solids content of up to 40% to the paper or cardboard web. The line forces between the applicator rollers are usually between 40 and 70 kN/m. Film presses can be equipped with all types of rollers common in the industry, such as: DE 10 2018 100 924 A1 described. It can be advantageous if at least one of the rollers is a shoe roller or a deflection-controlled roller, so that the pressing force acting in the roller nip can be adjusted to adjust the conditions in the treatment press nip depending on the properties of the product produced, such as sheet thickness, grammage or quality of the fiber material used and to optimize the starch transfer to the web.

Out of EP 2 603 636 B1 It is known to smooth the paper web using a calender. An application medium is sprayed directly onto the paper web while it rests on a calender roll. However, these processes have the disadvantage that errors in the application, such as those that occur when using spray nozzles (overlap errors, blockages, etc.), become directly visible in the paper.

A major disadvantage of the known arrangements is the high energy consumption of the configuration. Compromises have to be made in mechanical engineering and the production process, which often comes at the expense of paper quality.

The invention is therefore based on the object of creating a calender with which a uniform paper thickness and uniform cross-sectional profiles of the strength properties (CMT (flat compression resistance), SCT (strip compression resistance), RCT (burst resistance)) after a surface application of application media, in particular starch products Using cost-effective technology can be achieved.

This task is solved by the features of claim 1.

This creates a device for smoothing, which combines the process of pre-smoothing/profiling and a coating in one unit, whereby the application of the medium takes place indirectly and without contact, in which the medium is applied to at least one roller of the at least one nip. The transition of the application medium “into” the web is optimized according to the invention, while the prior art attempts to optimize the transition “onto” the web.

According to the invention, the measure for ensuring the strength properties of the paper or cardboard web, in particular the SCT value, remains the application of an application medium, in particular starch solutions, to the surface of the paper/cardboard. However, this is not done using a size press or a film press but rather using the smoothing device according to the invention. The smoothing device according to the invention combines the technological measures of leveling the web and the penetration of application medium, in particular starch, into the web in one unit.

Due to the pressure in the at least one nip of the smoothing device, the leveling of the web and the penetration of the application medium into the web are carried out technologically together and with a resulting common benefit. Surprisingly, it has been found that both treatment measures that influence paper strength can be combined to promote each other, namely through the combined Pressing pressure/hydraulic pressure on the paper or cardboard web as it passes through the at least one nip.

A major disadvantage of the prior art, namely the need for two independent units, is eliminated. The installation space does not pose a space problem for possible retrofitting. Fig. 12 shows an example and schematic of the structure of a paper or board machine according to the state of the art between - before the drying section (VTP) and after the drying section (NTP) - where the calender and film press are units set up one after the other. Fig. 13 shows an example and schematic of the device according to the invention for smoothing and with applicator 1 as a combination unit in a paper or cardboard machine in a comparable position.

If paper manufacturers therefore need/want to retrofit their existing systems with additional coating units and calenders, the solution according to the invention provides a high level of flexibility. No additional space is required. According to the state of the art, the installation of additional calenders and applicators would require an extension of the paper machine, so that installation in the existing factory hall would often no longer be possible. Compromises would have to be made in mechanical engineering and the production process, which often come at the expense of paper quality.

As an example of such a disadvantageous case according to the prior art, machines for the production of “flexible packaging” can be viewed. Due to the increasing conversion to waste paper fibers for cost reasons, it became necessary to smooth the paper web before coating. This space was not previously provided for in the machine configurations, which is why operators of these machines face major problems based on the state of the art.

It is to the credit of the inventors that they have recognized that uniform strength properties can be achieved across the width of the paper web, since the local pressing pressure that is necessary for profiling the paper web and the locally introduced amount of application medium, in particular the amount of starch, can be coordinated with one another. The required pressing pressure is determined by the local paper thickness. The amount of application medium supplied, in particular the amount of starch, is influenced by the specified pressing pressure.

The penetration of the application medium, especially the starch, and the resulting increase in paper strength is directly dependent on the local pressing pressure. This results in significantly improved paper strength properties (CMT, SCT, RCT) in places where there was previously a greater paper thickness. The increase in paper strength properties results from a higher proportion of starch (due to increased pressing pressure) and due to a higher density of the paper. As a result, this would result in an undesirable deviation in the strength of the paper in the CD direction, which is overcome according to the invention in that the at least one applicator has at least one delivery nozzle with a device for transverse profile adjustment of a volume flow that can be adjusted zone by zone over the web width.

What is crucial is that the quantity of starch application and the pressing pressure in one zone are coordinated with one another in such a way that the same paper strength properties result in all zones. This means that smaller amounts of starch have to be supplied in zones with a higher pressing pressure than in zones with low pressing pressure.

According to the invention, the implementation of this knowledge not only leads to significantly more uniform paper properties and thus to an improvement in quality, but also to a saving of starch and thus to cost savings for the customer. This invention therefore has a very high economic benefit.

According to the invention, a technologically and economically efficient technology for increasing the strength properties of the paper or cardboard by increasing the starch penetration is presented. This goal will achieved in accordance with the invention by using a contactless application method (preferably application method with a slot nozzle) that allows a very high solids content of starch to be applied (up to a maximum of 35%).

It is also possible to have a targeted influence on the cross profile by using the starch application and the pressing pressure, for example additively (higher pressure combined with a higher amount of starch), in order to achieve better strength properties in selected areas of the paper web (for example in the edge area). . Of course, the strength properties could also be worsened locally if this were to be an advantage for the further process of paper production. An example is the regulation of the application quantity with dilution water. Under certain circumstances, it may make sense to add more water to the edge area to prevent the edge of the paper from drying out, even if this reduces the starch content so that the strength properties become worse.

With the smoothing device according to the invention, the line force in the at least one nip can be profiled using, for example, a scanner in such a way that a desired thickness transverse profile is created. The volume flow of the application medium, in particular starch, can be adjusted with respect to the local, zone-controlled volume flow at the nozzle in order to regulate the application amount of medium/starch depending on the strength properties of the web.

Furthermore, the functional dependence of the paper strength on the parameters - properties of the starting materials and basis weights of the fiber materials used - can be taken into account as an influencing factor on the distribution and amount of the volume flow of application medium. Since the consistency of the fiber suspension at the exit of the headbox defines the basis weight produced, a consistency measurement value can be measured in each zone of the headbox using sensors. The measured consistency transverse and longitudinal profile can be used as a controlled variable in a control loop to determine the local Volume flow can be used in the CD direction. The headbox plays a key role in ensuring paper quality. Important paper properties are significantly influenced by the headbox. As part of automatic process control, the headbox is becoming increasingly influential as a correction element for targeted deviations that require downstream process steps, such as smoothing and coating. The smoothing device according to the invention makes use of this headbox correction element.

For the technical implementation of the invention, the use of a non-contact applicator with slot nozzles in conjunction with rollers of a device for smoothing serving as applicator rollers can be provided, with at least one applicator roller being designed as a zone-controlled profiling roller. These rollers are known, for example, under the name MHV roller or NIPCO roller. The zone widths are usually between 50 and 300 mm. The zones can be controlled individually and enable precise profile correction.

The application systems used are also divided into zones. Such order systems are among other things DE 10 2009 036 853 B3 and DE 10 2009 048 820 A1 known. These zones allow the application of different application medium/starch quantities across the machine width. This can be achieved, for example, by adding water to the individual zones, or by supplying different amounts of starch suspension per zone. Another simple method to apply different amounts of starch across the width of the machines can be to set different gap widths at the nozzle outlet using a gap adjustment.

This process is preferably possible at rather moderate temperatures (as is usual for starch penetration) due to the high moisture content of the fiber web in the calender nip. While the usual moisture content for conventional calendering is in a medium moisture range of 4% - 8%, it is Technology according to the invention, depending on the area of application, for example in the range between 20% to 60%.

Increasing the moisture content means that for the possibility of profiling, with a conventional calender with a moisture content of 8%, the temperature of the fibers must be approx. 80°C in order to deform them. At 4% humidity already 135°C. Since the temperature has to penetrate to a depth of approx. 15 µm to 20 µm in the short time of the nip passage in order to achieve sufficient deformation, the actual temperature of the roller surface must be approx. 20 - 30°C higher than the glass transition temperature .

In this respect, the technique according to the invention can differ significantly from conventional calendering. A key difference is that an already heated application medium can be introduced into the fiber web, which in turn increases the temperature of the fibers down to deeper layers. It is therefore not necessary to heat the rollers significantly higher than the glass transition temperature of the cellulose fibers.

Since the moisture content of the fiber web can range between 20% and 60%, the usual temperatures at which starch is applied (between 70°C and 100°C) are completely sufficient to profile the fiber web.

In order to enable high penetration of the starch into the paper web despite, for example, a high solids content, the starch can be pressed into the paper under high pressure and high temperatures, for example according to the invention.

One or both rollers of the smoothing device can be tempered. The rollers can also be provided with hard coatings (ceramic, chrome or the like), but can also be equipped with hard polymer covers.

One or both rollers can also be designed as soft rollers. The hardness of the surfaces is preferably less than 30 Pusey & Jones.

Further advantages and refinements of the invention can be found in the following description and the subclaims.

• Fig. 1a zeigt schematisch eine erfindungsgemäße Vorrichtung zum Glätten mit mindestens einem Auftragswerk im Querschnitt gemäß einem ersten Ausführungsbeispiel, vorzugsweise mit einem Vorhang-Auftragswerk,
• Fig. 1b zeigt schematisch eine erfindungsgemäße Vorrichtung zum Glätten mit mindestens einem Auftragswerk im Querschnitt gemäß einem zweiten Ausführungsbeispiel, vorzugsweise mit einem Freistrahl-Auftragswerk,
• Fig. 1c zeigt schematisch das Vorhang-Auftragswerk im Vergleich zum Freistrahl-Auftragswerk,
• Fig. 1d zeigt schematisch eine erfindungsgemäße Vorrichtung zum Glätten mit mindestens einem Vorhang-Auftragswerk im Querschnitt und einem zugeordneten Schnitt A-A in CD-Richtung gemäß einem dritten Ausführungsbeispiel,
• Fig. 2 zeigt schematisch eine erfindungsgemäße Vorrichtung zum Glätten mit mindestens einem Vorhang-Auftragswerk im Querschnitt und einem zugeordneten Schnitt B-B in CD-Richtung gemäß einem vierten Ausführungsbeispiel,
• Fig. 3 zeigt schematisch eine erfindungsgemäße Vorrichtung zum Glätten mit mindestens einem Vorhang-Auftragswerk im Querschnitt und einem zugeordneten Schnitt C-C in CD-Richtung gemäß einem fünften Ausführungsbeispiel,
• Fig. 4 bis Fig. 10 zeigen Schnitte in CD-Richtung gemäß weiterer Ausführungsbeispiele,
• Fig. 11 zeigt schematisch eine erfindungsgemäße Einstellung der Parameter Druckprofil und Auftragsprofil ausgehend von einem Profil Flächengewicht und einem Festigkeits-/Dickenprofil als Ergebnisgröße in CD-Richtung,
• Fig. 12 zeigt schematisch einen Teilabschnitt einer Papier- oder Kartonmaschine nach dem Stand der Technik,
• Fig. 13 zeigt schematisch einen Teilabschnitt einer Papier- oder Kartonbahn gemäß der Erfindung.

The invention is explained in more detail below using the exemplary embodiments shown in the accompanying figures.

• Fig. 1a shows schematically a device according to the invention for smoothing with at least one applicator in cross section according to a first exemplary embodiment, preferably with a curtain applicator,
• Fig. 1b shows schematically a device according to the invention for smoothing with at least one applicator in cross section according to a second exemplary embodiment, preferably with a free-jet applicator,
• Fig. 1c shows schematically the curtain applicator in comparison to the free jet applicator,
• Fig. 1d shows schematically a device according to the invention for smoothing with at least one curtain applicator in cross section and an associated section AA in the CD direction according to a third exemplary embodiment,
• Fig. 2 shows schematically a device according to the invention for smoothing with at least one curtain applicator in cross section and an associated section BB in the CD direction according to a fourth exemplary embodiment,
• Fig. 3 shows schematically a device according to the invention for smoothing with at least one curtain applicator in cross section and an associated section CC in the CD direction according to a fifth exemplary embodiment,
• Fig. 4 to Fig. 10 show sections in the CD direction according to further exemplary embodiments,
• Fig. 11 shows schematically an inventive setting of the parameters pressure profile and application profile based on a weight per unit area profile and a strength/thickness profile as the result variable in the CD direction,
• Fig. 12 shows schematically a section of a paper or cardboard machine according to the prior art,
• Fig. 13 shows schematically a section of a paper or cardboard web according to the invention.

As in Fig. 1a to Fig. 1d shown, the invention relates to a device for smoothing with at least one nip 6, which is formed between two rollers 3, 4. At least one of the two rollers 3, 4, here the roller 3, is designed to regulate a cross-thickness profile of a moving material web 9, in particular a paper or cardboard web, in the transverse direction of the web as a deflection-adjustable and zone-controlled roller 3.

For this purpose, the roller 3 has a roller shell 7 rotating around an axis of rotation, on the inner circumference of which support elements 5 exert a force. The support elements 5 form individual hydrostatic pressing elements. A plurality of support elements 5 are arranged distributed over the roller width and are divided into zones (print zone (1) to print zone (n)), so that print profiling is possible across the machine width. By means of the roller 3, also referred to as a profiling roller with MHV elements, it is therefore possible to set a local line load distribution that can be selected in the at least one nip 6 across the roller width/machine width.

The at least one nip 6 is therefore intended to level the cross-thickness profile of the material web 9 by means of an adjustable line load profile when the material web 9 passes through the nip 6. On the other hand and simultaneously with the exertion of a pressing pressure in the nip 6, an application medium 2 is introduced into the material web 9. For this purpose, at least one application unit 1 with a delivery nozzle 8 for applying application medium 2, in particular starch, is provided.

The at least one applicator unit 1 is arranged in such a way that the application medium 2 can be applied to at least one of the two rollers 3, 4 of the nip 6 is provided. The mass flow of application medium 2 is applied to the surface of at least one of the two rollers 3, 4 rotating in opposite directions, for example the roller 3 ( Fig. 1d ). As a result of the rotation of the rollers 3, 4, the application medium 2 applied to the surface of the roller(s) 3, (4) is conveyed towards the material web 9 and penetrates into the material web 9 in the press nip 6. This so-called indirect application of the application medium 2 to at least one side of the running material web 9 is therefore provided.

As in Fig. 1a shown, the application medium 2 can also be applied to both sides of the material web 9, for which purpose two applicators 1 are first applied to the rollers 3, 4. The rollers 3, 4 have the function of application rollers. The application medium 2 can in particular be starch, coating colors, plastic compounds such as PVA or a mixture of these media. The application medium 2 is then transferred to both sides of the material web 9, in particular a paper or cardboard web, in the press gap 6 between the rollers 3, 4. A roller, here the roller 4, is preferably a hard roller, particularly preferably a heated roller, which can be equipped with a ceramic cover. The other roller 3 is the bend-adjustable and zone-controlled profiling roller, which can be equipped, for example, with a hard ceramic cover or with a soft polymer cover with a hardness of less than 30 P&J, in particular 15-30 P&J.

As in Fig. 1a and Fig. 1d shown, the commissioned work 1 can be a curtain commissioned work. How Fig. 1b shows, a free-jet applicator can be used as an alternative to a curtain applicator for applying the application medium 2, in particular starch, on one or both sides to the rotating applicator roller 3, 4.

How Fig. 1c clarified, in a curtain applicator, a freely falling curtain of the application medium 2 forms in the outlet gap of the (dispensing) nozzle 8, which is constantly accelerated by the effect of gravity. The fall height of the curtain Application medium 2 between the outlet gap of the (dispensing) nozzle 8 and the point of impact on the application roller 3, 4 is usually 50 - 200 mm. A speed V2 of the curtain at the point of impact is therefore significantly higher than an exit speed V1 of the application medium 2 in the outlet gap of the (dispensing) nozzle 8.

How Fig. 1c further clarified, in the free jet applicator a free jet of the application medium 2 is generated in the outlet gap of the (dispensing) nozzle 8. In this case, a jet speed V4 at the point of impact and the exit speed V3 of the application medium 2 are approximately the same. The exit speed V3 of the application medium 2 from a free-jet applicator is significantly higher than the exit speed V1 from the (dispensing) nozzle 8 of a curtain applicator. The two different commissioned units 1 have their own operating windows with regard to machine speeds and line weights.

Fig. 1a thus shows a device for smoothing with applicators 1, for example curtain applicators, with which the application medium is applied on both sides with two slot nozzles 8 to the rollers 3, 4, which work as applicator rollers. The slot nozzle 8 is positioned relative to the respective roller 3, 4 so that the angle α for the point/location of the coating on the roller 3, 4 is, for example, between -45° and +45°. Fig. 1 b shows a device for smoothing with applicators 1, for example free-jet applicators, with which the application medium is applied on both sides with two slot nozzles 8 to the rollers 3, 4, which work as applicator rollers. The slot nozzle 8 is positioned relative to the roller 3, 4 so that the angle α can be in the range -90° and +45°.

In a known manner, the device according to the invention for smoothing and applying an application medium 2 can preferably have preparation troughs/squeegees 23, collecting troughs/guide plates 26, scrapers 27 and spray water or steam nozzles 28 for cleaning the (application) rollers 3, 4.

How Fig. 1d shows, according to the invention the at least one applicator 1 has at least one (dispensing) nozzle 8, which is assigned a device 13 for adjusting the cross-sectional profile of a mass flow 2 of the application medium 2 which can be adjusted zone by zone over the web width. Same as the AA cut Fig. 1d shows, the device 13 generates partial flows 22 of the mass flow 2, which are preferably continuously adjustable from zero to a maximum value predetermined by the applicator. The individual partial flows 22 can deliver different constant mass flows. The number of partial streams 22 can be selected.

How Fig. 1d shows in section AA, the applicator 1 is formed, for example, by a curtain applicator, the delivery nozzle 8 of which is divided into several sections 19. Starting from a cross-flow distributor 10, for example a starch suspension is distributed across the width via throttle valves 12 and diffusers 11. The mass flow 2 in the individual sections can be defined by partial flows 22 via the throttle valves 12. An actuator 16 for the respective throttle valve 12 is used here for automation. In principle, however, an adjustment can also be done manually.

The mass flow of application medium 2 is divided into partial flows 22 based on a number of sections 19 in a comparison with the pressure profiling in the nip 6 by the profiling roller 3. The pressure zones (1) to (n) formed can be the same, smaller or larger in CD- Direction can be selected like/as the zones of the sections 19 on application medium 2. The respective amount of application medium 2 in a partial stream 22 can be adjusted as well as the respective line load in the pressure zones (1) to (n) of the profiling roller 3. Together with a hydrostatic pressure element 5 of the profiling roller 3, which defines one of the pressure zones (1) to (n), an assigned section 19 can form a coherent zone.

If a starch agent is to be applied to both sides, the press gap 6 can be formed by two rollers 3, 4, both of which are designed as heated rollers can. Otherwise, the roller 4 is preferably designed like the roller 3 described above.

The line force in the press gap is preferably between 20 kN/m and 200 kN/m, preferably between 80 kN/m and 120 kN/m. The technique according to the invention can be used for starch application (sizing) and for pigmentation (pigmenting).

The starch is preferably applied with a solids content between 6% and 35%, particularly preferably between 15% and 35%, and a viscosity between 20 mPa s and 200 mPa s. The application weight is preferably in the range between 0.5 g/m ² and 6 g/m ² per side. A film of starch in the range of 10 ml/m ² to 40 ml/m ² can be applied to the smoothing roller with the additional function of an applicator roller.

When pigmented, the solids content can be between 15% and 40% and the viscosity can be between 50 mPa s and 400 mPa s. The application weight is preferably in the range between 2 g/m ² and 5 g/m ² per side.

Fig. 2 shows a fourth possible embodiment of the invention, among other things in section BB. The amount of application medium 2 supplied, in particular starch, can be regulated here by supplying dilution water. The starch suspension passes from the cross-flow distributor 10 via a feed 24 to the diffuser 11. Dilution water is introduced into the feed 14. The dilution water can be metered using a throttle valve 15. Otherwise, the comments apply Fig. 1.d .

In the Fig. 3 The locally desired application quantity of application medium 2, in particular the starch suspension, can be achieved via a zone-by-zone adjustment of an outlet gap 17 of the nozzle 8. For this purpose, the nozzle 8 can be equipped with a flexible lip 18 in the area of the nozzle gap 17. This can e.g can be positioned with the help of actuators 16. In section CC, the partial flows 22 are shown as a common, continuous mass flow field 25 in the CD direction. The enveloping profile line 21 stands as a border for the height of the mass flow in the CD direction.

The Fig. 4 to Fig. 10 show further possible arrangements and embodiments in section to illustrate the interaction according to the invention of the division of the (application) nozzle 8 into sections, the set amount of application medium 2 in the sections and the division into pressure zones by means of the profiling roller 3, in each case in the CD direction , ie, machine cross direction..

The Fig. 4 shows the direct assignment of a nozzle outlet zone to a pressure zone of the profiling roller according to the distribution principle of Fig. 1 . The outlet width here is the same as the effective area of the pressure zone. In addition, it is also possible to arrange the outlet zones and pressure zones in an overlapping or offset manner. This may be necessary, for example, to avoid streaking. Fig. 5 shows an overlapping arrangement with the same zone and outlet width.

The outlet widths of the (application) nozzle 8 do not necessarily have to have the same width as the effective zones of the pressing elements 5. Fig. 6 shows, for example, an arrangement in which the outlet widths are half as large as the effective width of the pressing elements 5. There are different zone and outlet widths with direct assignment.

Even if the outlet width is smaller, it can make sense to arrange the pressure zones (1) to (n) and the outlet positions in an overlapping manner, as in Fig. 7 shown. Fig. 7 shows different zone and outlet widths with an overlapping arrangement.

Of course, it is also conceivable to reduce the outlet widths even further if necessary. Lip adjustment is a suitable option here. The adjustment makes it possible to distribute the application medium over the Adjust the machine width very finely. This shows further possible variations Fig. 8 to Fig. 10. Fig. 8 shows a medium distribution over a gap adjustment with a division width equal to the pressure zone width. Fig. 9 shows a gap adjustment with a smaller pitch width than the pressure zone width with overlap. Fig. 10 shows a gap adjustment with different and variable pitch width as the pressure zone width.

The following applies equally to all of the aforementioned embodiments:
One or more scanners (not shown) can be assigned to the system, which record quality characteristics such as the paper thickness, the application weight or the paper moisture in the CD direction and prepare them for control purposes and make them available for cross-profile control.

The zone width of the profile setting on the slot nozzle 8 is, for example, 50 to 300 mm, preferably 150 to 280 mm.

The zone width of the hydrostatic elements 5 for profile correction is, for example, 50 to 300 mm, preferably 150 to 280 mm.

On at least one of the slot nozzles 8, the device for a zone-by-zone gap width adjustment or a device for zone-by-zone adjustable mass flow influencing is provided.

The hardness of the covers of the smoothing rollers 3, 4 is 0 to 30 P&J, preferably 0 to 5 P&J. The diameters of the smoothing rollers 3, 4 are preferably in the range 1000 to 1800 mm, particularly preferably 1200 to 1600 mm. The outlet gap 17 of the dispensing nozzle 8 is preferably 100 - 500 μm.

The pressure in each zone of the treatment nip 6 and the quantitative starch application are coordinated with one another in such a way that a desired cross-sectional profile of the paper thickness and strength properties (CMT, SCT, RCT) is achieved.

The zone of the application system and the assigned, subsequent pressing zone of the profiling roller are linked to one another in terms of control technology, so that an automatic comparison of pressing pressure and starch application quantity is possible. The entire system can be integrated into the process control system of the paper machine. Scanner data from the machine can be used to individually control the zones so that the desired paper strengths (CMT, SCT, RCT) can be set in the machine width. The macro surface roughness of the paper after treatment nip 6 is at Bendtsen <800 ml/min, preferably <500 ml/min.

The application weight of the starch is in the range 0.5 - 6 g/m ² per side. The line force in the press gap is between 20 kN/m and 200 kN/m, preferably between 80 kN/m and 120 kN/m. The surface temperature of at least one of the smoothing rollers 3, 4 is 60° to 160°C. The paper or cardboard web speed is preferably between 250 m/min and 2000 m/min, particularly preferably between 600 m/min and 1800 m/min. The dry content of the material web 9 is preferably more than 90% and is preferably between 92% and 98%. The starch can be applied with a solids content between 6% and 35%, preferably between 15% and 35% and a viscosity between 20 mPa s and 200 mPa s. The temperatures of the starch are preferably between 50°C and 110°C, particularly preferably between 70°C and 100°C.

• Die mindestens eine durchbiegungseinstellbare und zonengesteuerte Walze 3, mit der Einfluss auf die Liniendruckverteilung in dem mindestens einen Nip 6 genommen wird, ist zum Kalibrieren der Materialbahn 9 in Bahnquerrichtung regulierbar.
• Die mindestens eine durchbiegungseinstellbare und zonengesteuerte Walze 3, mit der Einfluss auf die Liniendruckverteilung in dem mindestens einen Nip 6 genommen wird, ist zur Beherrschung einer Dicke der Materialbahn 9 in Bahnquerrichtung regulierbar.
• Die mindestens eine durchbiegungseinstellbare und zonengesteuerte Walze 3 ist eine hydrostatisch abgestützte Walze mit zonenweiser Ansteuerung von Elementen 5 längs der Walzenbreite, wobei jede (Druck)Zone gruppenweise- oder einzelelementgesteuert ausgebildet sein kann.

For further design of the smoothing device according to the invention, the following is provided:

• The at least one deflection-adjustable and zone-controlled roller 3, which influences the line pressure distribution in the at least one nip 6, can be regulated in the transverse direction of the web to calibrate the material web 9.
• The at least one deflection-adjustable and zone-controlled roller 3, which influences the line pressure distribution in the at least one nip 6 can be regulated in order to control the thickness of the material web 9 in the transverse direction of the web.
• The at least one deflection-adjustable and zone-controlled roller 3 is a hydrostatically supported roller with zone-by-zone control of elements 5 along the roller width, whereby each (pressure) zone can be designed to be controlled in groups or individually.

How Fig. 11 shows, sensor devices, in particular scanners 30, can be provided which scan and/or detect the material web 9 on one or both sides in the transverse direction of the web in order to adjust the amount of pressure to be applied, ie pressure profile 33, depending on the surface quality and/or the thickness of the material web 9 in the transverse direction before entering the nip 6. Alternatively or additionally, a volume flow profile can be adjustable on the applicator by offline measurement of paper/cardboard web samples.

The transverse profile setting of the volume flow/mass flow of the application medium 2, which can be adjusted zone by zone over the web width, can be controlled depending on an area-related mass distribution of the material web 9 in the transverse direction of the web.

How Fig. 11 further shows, the consistency of a fibrous suspension in the outlet of the headbox 31, which defines the basis weight produced and its profile 32, can be used as an input variable for the amount of application medium 2 supplied zone by zone through the application nozzle 8 and its zones and throttle valves 12 ( Fig. 1 ) or actuators for lip adjustment ( Fig. 3 ) must be selected. The adjustable mass flows/volume flows are shown in the sectional views Fig. 1 to Fig. 11 shown as discrete arrows of the medium 2 or as a continuous current profile curve of the application medium 2.

Consistency sensors can be provided with which, at the resolution of an actuator pitch, a consistency transverse and longitudinal profile of a fibrous suspension in the outlet of the headbox can be measured, which can be selected as the input variable of a control circuit 35 for the amount of application medium 2 supplied in each zone. The adjustable line pressure distribution 33 and the adjustable quantitative application of application medium 2 can be coordinated with one another by means of a controller 36 in such a way that a compressed paper with a leveled surface with selectable strength properties (CMT, SCT, RCT) 34 can be produced in the transverse direction of the web.

Fig. 11 In particular, the technical context can be seen that areas of the paper or cardboard web with a higher basis weight of the paper or cardboard web are treated according to the invention with a higher line load and less application medium with simultaneous calibration and penetration of application medium, in particular starch, than areas of the paper or cardboard web. or lower basis weight paperboard web, where more application medium and lower line load are used to obtain a consistent strength/thickness profile.

The delivery nozzle 8 of the curtain applicator, which delivers the medium 2 under gravity, can finally have several slot nozzles 18, each with an outlet gap 8 with an accuracy in the range of ±2.5 µm to ±10 µm in gap length with a gap width of 100 to 2000 µm exhibit.

The curtain applicator 1 can be designed to control the solids content of the application medium 2 in at least one layer from 6% to 55%.

The curtain applicator 1 can be designed to form a multi-layer curtain.

The specific volume flow from the nozzle 8 of the curtain applicator 1 can be in the range from 4 l/(min xm) to 30 l/(min xm). On the respective smoothing roller 3, 4, a film of the application medium 2, in particular starch, is preferably applied in the range of 5 ml/m ² to 100 ml/m ² .

Furthermore, guide rollers (not shown) can also be provided, which can determine a treatment path of the running material web 9 between the curtain applicator 1 and the press gap 6.

A specific roller outer circumferential length, which corresponds to the dwell time, can be set between the moment the curtain 2 hits and its entry into the press gap 6 and the dwell time can thus be increased or reduced, as indicated by the angle α. If the smoothing roller 3, 4 is heated, the residence time can be used to influence a temperature increase of the application medium 2 before it enters the press gap 6. The application medium 2 can then be thermally pretreated in the press gap 6 between the smoothing rollers 3, 4 into the material web 9 be pressed in on one or both sides.

Claims (20)

Device for smoothing a paper or cardboard web (9) with at least one nip (6) which is formed between two rollers (3, 4), at least one of the rollers (3) being used to regulate a cross-thickness profile of the paper or cardboard web (9 ) in the web transverse direction, a deflection-adjustable and zone-controlled roller (3) is used to set a line load distribution that can be selected in at least one nip (6) over the roller width, characterized in that the at least one nip (6) is intended to use an adjustable line load profile to determine the cross-thickness profile of the paper - or cardboard web (9) and at the same time introduce an application medium (2) into the paper or cardboard web (9), for which at least one application unit (1) with a delivery nozzle (8) for applying application medium (2), in particular starch, is arranged in this way is that the application of the application medium (2) to at least one of the two rollers (3, 4) of the nip (6) is provided and for an indirect application of the application medium (2) to at least one side of the running paper or cardboard web (9) is designed, and the at least one applicator (1) has at least one dispensing nozzle (8) with a device (13) for adjusting the cross-sectional profile of a volume flow of the application medium (2) which can be adjusted zone by zone over the web width. Device for smoothing according to claim 1, characterized in that the at least one deflection-adjustable and zone-controlled roller (3), with which influence on the line pressure distribution in the at least one nip (6), is used to calibrate the paper or cardboard web (9). Web transverse direction can be regulated. Device for smoothing according to claim 1 or 2, characterized in that the applicator (1) is a curtain applicator or a free-jet applicator. Device for smoothing according to one of claims 1 to 3, characterized in that the at least one deflection-adjustable and zone-controlled roller (3) is a hydrostatically supported roller with zone-by-zone control of elements (5) along the roller width, each zone being designed to be controlled in groups or individually is. Device for smoothing according to one of claims 1 to 4, characterized in that sensor devices (30) are provided which scan and/or detect the paper or cardboard web (9) on one or both sides in the transverse direction of the web in order to adjust the level of pressure to be applied, depending on the surface quality and/or the thickness of the paper or cardboard web (9) in the transverse direction. Device for smoothing according to one of claims 1 to 5, characterized in that the transverse profile setting of the volume flow of the application medium (2), which can be adjusted zone by zone over the web width, is controlled in the transverse direction of the web depending on an area-related mass distribution of the paper or cardboard web (9). Device for smoothing according to one of claims 1 to 6, characterized in that the consistency of a fibrous suspension in the outlet of the headbox (31), which defines the basis weight produced, is selected as the input variable for the amount of application medium (2) supplied in each zone. Device for smoothing according to one of claims 1 to 7, characterized in that consistency sensors are provided with which a consistency transverse and longitudinal profile of a fiber suspension in the outlet of the headbox (31) can be measured in the resolution of an actuator division, which is used as an input variable Control circuit (35) is selected for the amount of application medium (2) supplied in each zone. Smoothing device according to one of claims 1 to 8, characterized in that the at least one nip (6) is designed for line loads in a range of 20 to 200 kN/m. Smoothing device according to one of claims 1 to 9, characterized in that the at least one nip (6) is designed as a hard nip or soft nip. Device for smoothing according to one of claims 1 to 10, characterized in that the delivery nozzle (8) has a plurality of slot nozzles, each with an outlet gap (17) with an accuracy in the range ±2.5 µm to ±10 µm in gap length with a gap width of 100 up to 2000 µm. Device for smoothing according to one of claims 1 to 11, characterized in that the spatial position of the at least one application unit (1) relative to the nip (6) is adjustable for an arrangement for indirectly applying the application medium (2) and controlling a dwell time of the application medium (2) on one of the two rollers (3, 4), which is also an application roller. Smoothing device according to one of claims 1 to 12, characterized in that the applicator (1) is designed to control the solids content of the application medium (2) in at least one layer from 6% to 55%. Smoothing device according to one of claims 1 to 13, characterized in that the applicator (1) is designed to form a multi-layer curtain. Device for smoothing according to one of claims 1 to 14, characterized in that zone widths of the profile adjustment on a slot nozzle of the delivery nozzle (8) and/or the hydrostatically supported elements (5) for the profile correction are 50 to 300 mm, in particular 150 to 280 mm, be. Device for smoothing according to one of claims 1 to 15, characterized in that at least one roller (3, 4) of the at least one nip (6) is designed as a heatable application roller and is designed for a temperature of the roller surface of 60°C to 160°C is. Smoothing device according to one of claims 1 to 16, characterized in that the rollers (3, 4) of the at least one nip (6) have coatings with less than 30 P&J. Device for smoothing according to one of claims 1 to 17, characterized in that an angle α for an impact point of the application medium (2) on an application roller (3, 4) of the press nip is between -90° and +45°. Device for smoothing according to one of claims 1 to 18, characterized in that the adjustable line pressure distribution and the adjustable quantitative application of application medium (2) can be coordinated with one another by means of a control (36) in such a way that a compressed paper or compressed cardboard with a leveled surface selectable strength properties (CMT, SCT, RCT) can be produced in the transverse direction of the web. Device for smoothing according to one of claims 1 to 19, characterized in that a volume flow profile on the applicator (1) can be adjusted by offline measurement of paper/cardboard web samples.

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