Classifications

• • 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
  • D21F3/0209—Wet presses with extended press nip
  • D21F3/0218—Shoe presses
  • D21F3/0227—Belts or sleeves therefor
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
  • D21G1/00—Calenders; Smoothing apparatus
  • D21G1/0066—Calenders; Smoothing apparatus using a special calendering belt

Definitions

• the present invention relates to a belt for a processing apparatus intended for treating a fiber web, said processing apparatus comprising a belt run adapted to travel around at least one guide element, outside said belt run being provided at least one counter-element creating a contact surface with the belt, such that between the belt and the counter-element is established a web processing zone, the web to be treated being passed therethrough.
• the invention further relates to a method for processing or treating a fiber web.
• a belt of the invention is characterized in that the belt comprises a layered structure, including a metallic outer layer, intended for contact with a fiber web to be treated, and at least one backing layer bonded to the metal layer's inner surface.
• a method of the invention is in turn characterized by what is set forth in the characterizing clause of claim 8.
• a single- or multi-component backing layer flexible and/or compressible include e.g. the fact that pressure is transmitted evenly in the nip and vibration of the belt can be dampened, hence improving the stability and, consequently, runnability of the belt.
• the layer- structured belt is also beneficial in terms of reducing noise caused by scuffing between belts and rolls.
• the metal layer By using a backing layer, it is possible to make the metal layer thinner than when using a purely metallic belt, and this enables enhancing the process regarding the use of a heated metal belt as heat is able to transfer rapidly from the belt to a presently processed web which has its surface portion converting to a plastic state and then cooling rapidly, the polymers contained in the web converting from a plastic state to a glassy state and the conversion remaining permanent.
• Heating of the belt's metal layer and a rapid transfer of heat therefrom to the web can be enhanced by making the backing layer from a heat insulating or poorly conducting material. In this case, the heat transfers from the metal layer only towards the web and simultaneously the metal layer cools quickly.
• a thinner metal belt improves bending strength, whereby the diameter of guide rolls can be reduced.
• the currently employed thickness is typically 0,6 mm, while with the inventive belt, provided with a backing layer, the thickness of a metal layer can be less than about 0,3 mm, and preferably it can be less than about 0,1 mm.
• fig. 1 shows schematically one processing apparatus applying a belt of the invention
• fig. 2 shows one embodiment of the belt structure in a schematic partial view
• fig. 3 shows a second embodiment of the belt structure in an enlarged sectional view.
• Fig. 1 shows one processing apparatus applying a belt solution of the invention and designed as a belt calender, comprising a calendering belt 2 which travels around guide rolls 3, at least some of said guide rolls being displaceable for adjusting the belt's 2 tightness and/or the processing zone length as desired.
• the calendering belt 2 travels around a roll 5 disposed on its outside, establishing a calendering zone between the belt 2 and the roll 5.
• a material web W to be calendered passes through the calendering zone, being thus exposed to a desired pressure impulse and heat effect as a function of time. Depicted with a dash-and-dot line 9 in fig.
• a dash line 8 depicts the shape of a pressure effect whenever the contact pressure existing in the calendering zone is established solely by means of the belt's 2 tightness as the nip roll 4 is out of contact with the belt 2 (or when there is no nip roll 4 installed inside the belt 2).
• the roll 5, and likewise the nip roll 4 may or may not be a deflection-compensated roll and can be selected from a group consisting of: a flexible surface roll, such as a polymer-coated roll, a rubber-coated roll or an elastomer-surface roll, a shoe roll, a thermal roll, a metal roll, a fiber roll, and a composite roll.
• the press element may comprise some other profilable or fixed- profile press element, which may further consist of several elements successive in a cross-machine direction.
• the roll-shaped press element 4 may also consist of several elements successive in a cross-machine direction.
• the press element 4 may have a surface which is designed to be continuous or discontinuous.
• the press element 4 can also be adapted to be displaceable for varying the processing zone length and/or the belt's tightness.
• the belt 2 comprises a metallic outer layer 10, intended for contact with a presently treated fiber web W, and a backing layer 11 bonded to the metal layer's inner surface and preferably selected from a group consisting of: rubber, polyurethane, a composite material, felt, aramid (e.g. kevlar®), or combinations thereof.
• a higher pressure zone established by the nip roll 4 can be widened as compared to what is achieved with a substantially non-compressible belt.
• the backing layer dampens vibrations and thus improves the belt's controllability.
• Fig. 3 shows a second exemplary embodiment of the belt 2, in which to the backing layer's 11 inner surface is bonded a second metal-belt layer 12, which is preferably thicker than the outer surface layer 10.
• the outer surface layer 11 has a thickness which is preferably within the range of about 0,1-0,3 mm and the inner metal layer 12 can be within the range of about 0,3-1 mm.
• the backing layer 11 is preferably within the range of about 3-10 mm.
• the nip roll 4 comprises a deflection- compensated roll.
• Reference numeral 6 represents heating elements, such as for example an induction heater, an infrared radiator, a gas burner, or a capacitive heater.
• the inventive belt solution can be provided with elevated temperatures, for example from higher than about 100°C to higher than about 200°C and even to as high as 400°C, depending on a particular application.

Landscapes

• Treatment Of Fiber Materials (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)

Applications Claiming Priority (2)

Publications (2)

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ID=8566185

Family Applications (1)

Country Status (4)

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Family Cites Families (5)

• 2003
  • 2003-05-30 FI FI20030815A patent/FI113881B/fi not_active IP Right Cessation
• 2004
  • 2004-04-20 EP EP04728363A patent/EP1636417B1/de not_active Expired - Lifetime
  • 2004-04-20 AT AT0915804A patent/AT502000B1/de not_active IP Right Cessation
  • 2004-04-20 WO PCT/FI2004/050042 patent/WO2004106628A1/en active IP Right Grant

Non-Patent Citations (1)

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