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BR-102023009702-B1 - DEVICE FOR SMOOTHING AND APPLYING TREATMENT SUBSTANCE

BR102023009702B1BR 102023009702 B1BR102023009702 B1BR 102023009702B1BR-102023009702-B1

Abstract

DEVICE FOR SMOOTHING AND APPLYING TREATMENT SUBSTANCES. The present invention relates to a device for smoothing a sheet of paper or cardboard (9) with at least one nip (6) formed between two rollers (3, 4), wherein at least one of the rollers (3) for controlling a cross-sectional thickness profile of the sheet of paper or cardboard (9) in the transverse direction of the paper is a roller with adjustable deflection and zone-controlled (3) to define a line load distribution over the width of the roller that can be selected on at least one nip (6), wherein the at least one nip (6) is provided for smoothing the cross-sectional thickness profile of the sheet of paper or cardboard (9) by means of an adjustable line load profile and simultaneously introducing a treatment medium (2) into the sheet of paper or cardboard (9), for these proposals, at least one coater (1) with an outlet nozzle (8) for application of the application medium (2), in particular starch, is arranged so that the application of the treatment medium (2) on at least one of the two rollers (3, 4) of the nip (6) is provided and designed for indirect application of the treatment medium (2) on at least one side of the sheet of paper or cardboard (9) and (...).

Inventors

  • EDUARD DAVYDENKO
  • Andreas Pesch
  • Gerald Steiner

Assignees

  • ANDRITZ KÜSTERS GMBH

Dates

Publication Date
20260310
Application Date
20230519
Priority Date
20220524

Claims (20)

  1. 1. Device for smoothing a sheet of paper or cardboard (9), having at least one nip (6) formed between two rollers (3, 4), wherein at least one of the rollers (3) for controlling a cross-sectional thickness profile of the sheet of paper or cardboard (9) in the transverse direction of the sheet is a roller (3) adjustable in terms of deflection and zone-controlled, in order to adjust a line load distribution over the width of the roller in at least one nip (6), characterized in that at least one nip (6) is provided for smoothing the cross-sectional thickness profile of the sheet of paper or cardboard (9) by means of an adjustable line load profile to level the cross-sectional thickness profile of the sheet of paper or cardboard (9) and simultaneously introduce a treatment medium (2) into the sheet of paper or cardboard (9), for which purpose at least one coater (1) having a dispensing nozzle (8) for applying the treatment medium (2) is arranged so that the application of the treatment medium (2) in at least one of the two rollers (3, 4) of the nip (6) is provided and is designed for indirect application of the treatment medium (2) on at least one side of the paper or cardboard sheet (9) and the at least one coater (1) has at least one dispensing nozzle (8) with a device (13) for cross-profile adjustment of a volume flow of the application medium (2) that can be adjusted by zone of the sheet width, wherein the roller (3) adjustable in terms of deflection and zone-controlled is a hydrostatically supported roller with zone-controlled elements (5) along the width of the roller, which are arranged distributed over the width of the roller and are in pressure zones, wherein the dispensing nozzle (8) is subdivided into multiple sections (19) with an outlet zone, wherein said outlet zones and pressure zones are arranged in overlapping or offset.
  2. 2. Smoothing device according to claim 1, characterized in that at least one zone-controlled adjustable deflection roller (3), by means of which the line load distribution in at least one nip (6) is controlled, is adjustable to calibrate the paper or card sheet (9) in the transverse direction of the sheet.
  3. 3. Smoothing device according to claim 1 or 2, characterized in that the coater (1) is a curtain application unit or a free jet application unit.
  4. 4. A smoothing device, according to any one of claims 1 to 3, characterized in that each zone is designed to be controlled by groups or by individual elements.
  5. 5. Smoothing device, according to any one of claims 1 to 4, characterized in that sensor means (30) are provided that scan and/or detect the sheet of paper or cardboard (9) on one or both sides in the transverse direction of the sheet to adjust the amount of pressure to be applied, depending on the surface quality and/or thickness of the sheet of paper or cardboard (9) in the transverse direction.
  6. 6. Smoothing device, according to any one of claims 1 to 5, characterized in that the transverse profile adjustment of the volume flow of the application medium (2), which can be adjusted by zone in the width of the sheet, is controlled as a function of a mass distribution related to the area of the paper or cardboard sheet (9) in the transverse direction of the sheet.
  7. 7. Smoothing device, according to any one of claims 1 to 6, characterized in that the consistency of a pulp suspension at the outlet of the inlet box (31), which defines the basic weight produced, is selected as an input variable for the amount of treatment medium (2) supplied per zone in each case.
  8. 8. Smoothing device, according to any one of claims 1 to 7, characterized in that consistency sensors are provided with which a transverse and longitudinal consistency profile of a fibrous material suspension at the outlet of the inlet box (31) can be measured at the resolution of a division of the actuator, whose profile is selected as the input variable of a control loop (35) for the amount of treatment medium (2) supplied per zone in each case.
  9. 9. Smoothing device, according to any one of claims 1 to 8, characterized in that at least one nip (6) is designed for line loads in a range of 20 to 200 kN/m.
  10. 10. Smoothing device, according to any one of claims 1 to 9, characterized in that at least one nip (6) is designed as a hard nip or a soft nip.
  11. 11. Smoothing device, according to any one of claims 1 to 10, characterized in that the dispensing nozzle (8) comprises a plurality of slot nozzles, each having an outlet gap (17) with an accuracy in the range of ±2.5 μm to ±10 μm in the length of the gap in a gap width of 100 to 2000 μm.
  12. 12. Smoothing device, according to any one of claims 1 to 11, characterized in that the spatial position of at least one coating roller (1) in relation to the nip (6) is adjustable for an arrangement for indirect application of the treatment medium (2) and control of the residence time of the treatment medium (2) on one of the two rollers (3, 4) which is simultaneously an applicator roller.
  13. 13. Smoothing device, according to any one of claims 1 to 12, characterized in that the coating device (1) is designed to control the solids content of the treatment medium (2) in at least a 6% to 55% layer.
  14. 14. Smoothing device, according to any one of claims 1 to 13, characterized in that the coating device (1) is designed to form a multilayer curtain.
  15. 15. Smoothing device, according to any one of claims 1 to 14, characterized in that the profile adjustment zone widths in a slot nozzle of the distribution nozzle (8) and/or the hydrostatically supported elements (5) for profile correction are 50 to 300 mm.
  16. 16. Smoothing device, according to any one of claims 1 to 15, characterized in that at least one roller (3, 4) of at least one nip (6) is designed as a heatable applicator roller and is designed for a roller surface temperature of 60°C to 160°C.
  17. 17. Smoothing device, according to any one of claims 1 to 16, characterized in that the rollers (3, 4) of at least one nip (6) have coatings with less than 30 P&J.
  18. 18. Smoothing device, according to any 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°.
  19. 19. Smoothing device, according to any one of claims 1 to 18, characterized in that the adjustable line load distribution and the adjustable quantitative application of the treatment medium (2) can be combined with each other by means of a control system (36), so as to produce a compacted paper or a compacted plate with a leveled surface having selectable strength properties (CMT, SCT, RCT) in the transverse direction of the sheet.
  20. 20. Smoothing device, according to any one of claims 1 to 19, characterized in that a volumetric flow profile in the coating unit (1) is adjustable by means of off-line measurement of paper/cardboard sheet samples.

Description

[001] The invention relates to a smoothing device comprising at least one nip formed between two rollers, wherein at least one of the rollers is a deflection-compensated, zone-controlled roller for regulating a thickness profile of a paper or cardboard, according to the preamble of claim 1. [002] As of WO 2004/001132 A2, machines are known that allow the production and treatment, including the application of a treatment substance on at least one side of the material sheet in an operation called online or offline. For many applications, a smoother and possibly glossier material quality is desired. To achieve this quality, the machine has a material sheet smoothing device along the material sheet path, at least upstream of the application device. The use of a material band smoothing device before the application of the treatment medium is particularly convenient and effective insofar as the non-contact application process, in particular the coating process, largely preserves the surface contour of the material sheet. This means that a rough contour of the material is not, or is only comparatively small, leveled and therefore smoothed by the treatment substance. The smoother the sheet is before the application of the treatment medium, the higher the productivity. Therefore, it has been found that it is better to smooth the surface first and then apply the treatment substance than to smooth a rough contour after coating. Regarding the application of the treatment substance, it is preferable to use the so-called curtain coating process. [003] Non-contact starch application processes, for example, curtain sizer and spray sizer, are known from EP 3 617 403 A1 and AT 519598 A2, WO2020020626A1. In these processes, the application quantity is measured by means of a quantity control on the application nozzles themselves. Blade devices are not required here. [004] From EP 0 374 292 A1 onwards, devices for smoothing and calibrating paper are known, which compact and smooth the paper. Variations in paper thickness are compensated for and the paper is calibrated. The result is compacted paper with a level surface. This requires accepting uneven density, reduced thickness, stiffness, and opacity. To calibrate paper, that is, to give it an identical thickness in all places, the pressure given by the weight of the calender rolls themselves is normally very low. Therefore, the calender is subjected to additional pressure. To avoid limiting the system's flexibility to a few base weight-pressure pairs, one of the rolls is preferably designed as a zone-controlled deflection compensation roll, which replaces a rigid crown. [005] Currently, paper manufacturers frequently face the challenge of using increasingly more recovered paper fibers (recycled fibers) in paper production, especially packaging papers and boards, as well as specialty papers. For example, testliner in the EU is mainly made from recovered paper and fillers. Due to a high proportion of secondary fibers, the strength properties of packaging papers decrease. The use of starch in paper production can compensate for the loss of strength. In general, starch is added directly to the pulp suspension or sprayed onto the wet sheet in the wire section. In addition, starch can be applied to the paper sheet immediately after pre-drying using contact or non-contact application methods. [006] Testliner and folding paperboard can have multiple coatings. After pigment coating on the film press, an intermediate coating layer and a top coating layer are typically applied to the paper sheet with a bladecoater. The subsequent coating process with a bladecoater requires a smooth base paper surface (Bendtsen surface macro roughness < 500 ml/min, PPS surface micro roughness < 3μm) and a very uniform paper thickness (2sigma deviation < 1% - 1.5%). The paper thickness should exhibit only small deviations in the paper sheet width. For this reason, pre-smoothing with a smoothing unit or with the aid of a hard-nozzle calender is also usually performed here, to pre-smooth before coating and to calibrate the paper thickness. For smoothing one side of the testliner and folding paperboard, only one nip is used. Ideally, a rolling mill consists of two rolls, specifically a heated steel or cooled cast iron roll and an unheated profiling roll. In most cases, thickness control between profiles is achieved with zone-controlled elements. [007] Sizing presses and film presses are known as contact application methods, as described, for example, in DE 3417487 A1 and DE 4131131 A1. Starch or sizing agent is applied to an applicator roll by means of a metering applicator and metered by means of a scraper blade. The sheet of paper or cardboard is coated on both sides in a press nip between the applicator rolls. The starch temperature 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/m2 per side. In some cases, it is als