Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
  • D21G1/00—Calenders; Smoothing apparatus
  • D21G1/02—Rolls; Their bearings
  • D21G1/0246—Hard rolls
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F3/00—Press section of machines for making continuous webs of paper
  • D21F3/02—Wet presses
  • D21F3/08—Pressure rolls
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C13/00—Rolls, drums, discs, or the like; Bearings or mountings therefor
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49544—Roller making
  • Y10T29/4956—Fabricating and shaping roller work contacting surface element
  • Y10T29/49563—Fabricating and shaping roller work contacting surface element with coating or casting about a core

Definitions

• the invention relates to a method for sealing the coating of a roll and particularly an intermediate layer thereof, particularly of a press roll such as the centre roll of a press or the back-up roll of an extended-nip press roll, or of a calender roll used in a pulp, paper, board or finishing machine, and, further, to a roll and a coating for a roll.
• a press roll such as the centre roll of a press or the back-up roll of an extended-nip press roll, or of a calender roll used in a pulp, paper, board or finishing machine
• the coating of a roll particularly a thermally sprayed coating, can be improved in terms of its corrosion resistance and impermeability by virtue of applying a sealing to the coating.
• rolls with ceramic and cermet coatings have by large replaced granite rolls used earlier in the art.
• corrosion of various degrees occurs, in particular in more severe conditions, causing corroding of the roll, delamination of the coating and wear of the roll so that it gradually becomes unusable.
• a coating made on a roll by way of thermal spraying always remains somewhat porous, thus allowing gradual penetration of moisture through the porous surface toward the inner metallic layers thus causing corrosion and so the protection offered by the coating against corrosion is insufficient.
• Process conditions in the paper and board industry have continually become more and more severe and demanding on the equipment, among other reasons, due to the trend toward enhanced circulation of process water for environmental protection and change of the process environment in a more corrosive direction.
• the object of the present invention is to provide an impervious coating for a roll used in a paper or board machine and a method for sealing the coating of a roll and, further, a roll having an impervious surface.
• the coating, method and roll according to the invention are characterized by what is stated in the claims.
• the shortcomings of conventional methods known in the art for sealing surface coatings in paper or board machines can be avoided or decisively reduced by virtue of the method described in the following .
• the invention is based on intermediate sealing of a thermally sprayed coating such as a ceramic coating, whereby the sealing step is carried out prior to the application of the outermost surface layer. Sealing of the coating is performed so that, during the surfacing of a roll, the application of the coating is stopped when a given thickness of coating has been reached and subsequently the sealing treatment is carried out, or alternatively the coating application may be continued and a plurality of such sealing treatments can be carried out. After the last sealing treatment, the coating process is continued up to the final coating thickness.
• the sealing agent remains entrapped under the final ceramic coating layer proper, which acts as the functional coating, and thus prevents substances corrosive to the roll frame from reaching the metallic inner part of the roll.
• the sealing of the intermediate layers may also be performed on a metallic adhesion or corrosion protection layer applied to the outer surface of the metallic roll or, alternatively, to a selected area thereof, and/or said adhesion or corrosion protection layer is next covered with a ceramic layer of a given thickness that is sealed to form an intermediate layer in the above-described manner, whereupon the ceramic coating can be prepared by spraying to its final thickness.
• the surface is subjected to an adhesion- improving complementary treatment prior to the spraying of the next coating layer.
• FIG. 1 shows an embodiment of an impervious roll coating according to the invention, wherein the illustrated details are not limiting to the invention.
• FIG. 1 shows a coating consisting of several layers.
• an adhesion/corrosion protection layer 2 On the outer surface of a roll mantle, an adhesion/corrosion protection layer 2 has been applied out of a metal or metal alloy.
• the layer 2 has been sealed by means of a sealing agent.
• the sealed layer is designated by reference symbol I.
• at least one ceramic layer 3 and 4 has been applied on the layer I.
• the layer 4 is sealed (second sealed intermediate layer) and the sealed layer is designated by reference symbol II.
• On the layer II has been applied by spraying a ceramic layer 5 up to the desired final thickness.
• the number of sealed layers may be varied in the coating system, whereby sealed layers may be interleaved with unsealed layers, but advantageously all the layers are made sealed. It is essential that the outermost layer 5 is free from sealing agent.
• the ceramic layers 3-5 may comprise either similar or different ceramic material and, respectively, the sealed intermediate layers I and II may comprise either similar or different sealing agent.
• the thicknesses of the individual layers may be varied within comparatively large limits, a typical layer thickness being in the range of 50- 500 ⁇ m.
• water-soluble compounds such as water-soluble polymer resins, of which preferred ones are acrylate esters, water-based epoxy resin systems and UV-curable acrylate esters and urethane acrylates as well as inorganic sealing agents, advantageously aluminium orthophosphate, or mixtures of the above-mentioned compounds.
• other synthetic organic polymer resins such as epoxy resins, phenolic resins, polyurethane resins and silicone resins, as well as fluorine-containing resins that are curable by conventional techniques may be used as sealing agents.
• sealing agents are particularly water-soluble acrylate esters and UN-curable acrylate esters.
• the sealing agents used are featured by a low viscosity, low surface tension, a suitable hardening mechanism for the intended application, small curing shrinkage and sufficiently good corrosion protection capability.
• the sealing agent is applied at a desired step of the coating process to the surface by spreading, spraying or some other conventional means suitable for impregnating the surface layer.
• the sealing agent penetrates the coating layer pores up to a depth determined by the pore structure of the layer (which is affected by spraying velocity and material composition plus particle size) and the technique of sealing agent application.
• the layer to be sealed can be impregnated with the sealing agent down to the entire radial depth of the layer or by a partial depth of the layer. Excess sealing agent remaining on the layer surface can be removed, e.g., by wiping prior to launching the next process step.
• the sealing agent is cured if so required before the onset of the next step.
• the treated surface is first subjected to a suitable further treatment and the sealed layer is cleaned free from organic and mechanical impurities before the coating process is continued.
• Advantageous further treatment techniques are flame treatment, mild shot blasting, solvent treatment, washing, abrasive grinding, carbon dioxide blasting, steaming and combinations thereof carried out prior to the spraying of the next or final coating layer.
• the most important benefits of the intermediate layer sealing method according to the invention and of the coating with the sealed intermediate layers, as well as of the roll made using the method according to the invention are a good impermeability and corrosion resistance of the coating.
• the sealing of the intermediate layers does not detrimentally affect the grinding of the coating or plug a grinding wheel as frequently occurs with rolls having their ceramic surface sealed with resins or waxes.
• Rolls having a surface coating made with sealed intermediate layers do not impair the runnability of a paper machine in regard to, e.g., detaching of the web, whereby the controlled porosity of the ceramic surface layer of the roll coating is an essentially contributing factor. Sealing the roll surface by its intermediate layer or layers leaves the roll outer surface intact, whereby sealing does not alter its properties as is the case with sealing the roll surface by waxes or resins.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Paper (AREA)
• Coating By Spraying Or Casting (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Rolls And Other Rotary Bodies (AREA)
• Sealing Battery Cases Or Jackets (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (1)

Family

ID=8553759

Family Applications (1)

Country Status (10)

Cited By (3)

Families Citing this family (5)

Citations (5)

Family Cites Families (11)

• 1999
  • 1999-02-15 FI FI990298A patent/FI117945B/fi active IP Right Grant
• 2000
  • 2000-02-15 EP EP00905089A patent/EP1169578B1/en not_active Expired - Lifetime
  • 2000-02-15 WO PCT/FI2000/000109 patent/WO2000049301A1/en not_active Ceased
  • 2000-02-15 AU AU26739/00A patent/AU2673900A/en not_active Abandoned
  • 2000-02-15 CA CA002362892A patent/CA2362892C/en not_active Expired - Fee Related
  • 2000-02-15 AT AT00905089T patent/ATE276447T1/de not_active IP Right Cessation
  • 2000-02-15 DE DE60013794T patent/DE60013794T2/de not_active Expired - Fee Related
  • 2000-02-15 JP JP2000600012A patent/JP2002537500A/ja active Pending
  • 2000-02-15 CN CNB008037736A patent/CN1142373C/zh not_active Expired - Fee Related
• 2001
  • 2001-08-13 US US09/928,556 patent/US6609996B2/en not_active Expired - Fee Related

Patent Citations (5)

Non-Patent Citations (2)

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