Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F5/00—Dryer section of machines for making continuous webs of paper
  • D21F5/02—Drying on cylinders
  • D21F5/021—Construction of the cylinders
• • 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
  • D21F3/10—Suction rolls, e.g. couch rolls

Definitions

• the present invention relates to a roll to be used in the dryer section of a web forming machine, where a fabric is arranged to travel over the roll, and which roll includes a shell and end pieces at both ends of it to support the roll rotatably in the web forming machine, and in connection with which roll means are arranged for creating a pressure or temperature difference inside the roll, relative to its environment.
• the rolls are separate from each other. In other words, these are nip-free positions.
• the roll has a cylindrical shell, at the ends of which end pieces are also installed. By means of the end pieces,' the roll is supported rotatably in the web forming machine.
• suction rolls In a dryer section, there are mainly two kinds of hollow roll, suction rolls and dryer cylinders. The suction rolls in question are also referred to as suction hitch rolls. In the suction rolls there is a perforated shell, whereas in a dryer cylinder hot steam is led inside.
• the dryer cylinders are used to heat the web to dry it while the suction rolls are used to hold the web under control on top of the dryer wire used as the fabric.
• VAC-roll is also used for a large-diameter suction roll in the dryer section and is used mainly in connection with a one-wire draw.
• the invention is intended to create a new type of roll to be used in the dryer section of a web forming machine, which is lighter than previously and is dynamically more stable an by means of which the drawbacks of the prior art can be avoided.
• the characteristic features of the present invention are stated in the accompanying Claim 1.
• a particularly thin shell is used. This is achieved by using a thin-sheet material, which is stiffened in a new and surprising manner.
• the sheet construction avoids the difficult casting and drilling of the thick shell.
• the finished roll is also considerably lighter than conventional rolls. This reduces the power required to rotate it while the roll can be supported on smaller bearings than previously. On the other hand, it is possible to make considerably larger rolls than before, without restrictions of mass or vibration.
• the roll according to the invention is ready for use without machining. If necessary, a cover can be used, which can be machined to adjust the properties of the surface of the roll as desired.
• the end piece of the roll is also of a new type and utilizes bodies of revolution and plate structures.
• Figure 2a shows an axonometric view of a roll according to the invention
• Figure 2b shows a partial cross-section of a shell of the roll according to the invention
• Figure 3a shows a partial cross-section of a roll according to the invention
• Figure 3b shows a partial cross-section of a third adaptation of the shell of a roll according to the invention
• Figure 4 shows a cross-section of a roll according to the invention
• Figure 5 shows a partial cross-section of the end piece of the roll
• Figure 6a shows a cross-section of an application of the roll according to the invention
• Figure 6b shows a partial cross-section of Figure 6a along the plane A-A.
• Figure 1 shows one cylinder group, of which there are several consecutively in the dryer section of a web forming machine.
• Known web forming machines are, for example, paper and board machines, and other similar machines.
• the cylinder group consists of consecutive drying cylinders 10 and suction rolls
• Figure Ib shows only the drying wire 12, without the web.
• Means for creating a pressure or temperature difference inside the roll, relative to the environment, are additionally arranged in connection with the roll.
• the vacuum line 14 and the steam line 15 are shown schematically in Figure Ia. The vacuum and steam are produced in some known manner and are led to the rolls through the aforementioned lines .
• Figure 2a shows an axonometric view of the roll according to the invention.
• the roll thus includes a shell 16 with end pieces 17 at each end of it, to support the roll rotatably in the web forming machine.
• One embodiment of the end piece 17 is shown in greater detail in Figure 5.
• Figure 2a shows a suction roll, in which there is a perforated shell 16. An individual hole is shown with the reference number 26.
• the roll according to the invention appears to be largely conventional, but its construction is entirely new and surprising.
• the shell 16 is actually of a thin-sheet material.
• a stiffener structure 18 ( Figure 2b) is fitted inside the shell 16. This avoids casting and its consequent restrictions .
• the roll becomes considerably lighter than previously and more advantageous in terms of vibration.
• the stiffener structure is also of thin-sheet material, so that both the shell and the stiffener structure can be manufactured using the same means and methods.
• the thickness of the thin-sheet material is 1 - 5 mm, preferably 2 - 4 mm.
• One preferred material is cold-rolled sheet steel that has no residual stresses. Thus during and after cutting the thin-sheet pieces will remain straight and elastic recovery during bending will be small.
• Figure 2b shows a partial cross-section of the shell 16 of the roll according to the invention.
• the height of the stiffener structure 18 is about 5 - 30 %, preferably 10 - 20 % of the roll's outer diameter. In that case, the size of the stiffener structure will remain reasonable and simplified structures can be used. The height of the stiffener structure is, however, at least 100 mm, so that the manufacturing methods will remain simple.
• the stiffener structure 18 is formed of several stiffener pieces 19, which are fitted at a distance from each other.
• the stiffener piece is formed of a stiffener profile, which is attached to the inner surface of the shell.
• each stiffener piece 19 is bent from a thin-sheet material and attached to the inner surface of the shell 16, for example, by welding. Though in terms of attachment of the stiffener piece 19 shown is preferred, other shapes of stiff ⁇ ener piece can also be used.
• the stiffener pieces 19 are attached very close to each other.
• the stiffener pieces 19 are clearly separate. The shape and size of the stiffener piece and the distance between them are dimensioned as required, taking into account the size of the roll and its operating application and purpose.
• the stiffener pieces are also perforated, to ensure the even spread of the vacuum effect.
• the vacuum is introduced to the suction roll, for example, through a hollow protruding shaft 20 ( Figure 2a) .
• Figure 3a A second embodiment of the roll according to the invention is shown in Figure 3a.
• the stiffener piece 19 consists of a circular ring, which is attached to the inner surface of the shell 16.
• the circular ring is simple to manufacture and it will easily create sufficient stiffness.
• the grooves are in the cover, instead of being in the base material of the roll, which will further simplify the manufacture of the roll.
• the shape of the groove can be selected more freely.
• Figure 3 shows a third embodiment of the roll according to the invention.
• the stiffener pieces 19 are connected to each other in the longitu ⁇ dinal direction of the roll, by means of an intermediate support 23.
• the intermediate support prevents the stiffener pieces from bending when the roll is loaded, thus forming an extremely stiff cell structure.
• the intermedi ⁇ ate support 23 is formed of a cylindrical support piece 24, which extends from one end piece of the roll to the other, and which is attached to each stiffener piece 19.
• longitudinal support pieces which are attached to the circumference of the shell at specific intervals.
• the cylindrical support piece 24 extends over the entire length of the shell 10 and is attached to a special installation plate 25.
• the shell can be manufactured separately and finally the end piece can be attached to the installation plate.
• these must be perforated or have larger openings, to permit the vacuum to spread evenly through the whole area of the shell.
• the stiffener pieces and/or the support piece there is perforation or similar.
• the dimensions and location of the holes can be selected more freely than previ ⁇ ously. In that case, the vacuum effect can be applied differ ⁇ ently at different points in the shell. For example, at the end parts of the shell, i.e.
• a stronger vacuum can be formed, especially to control the edges of the web.
• perforation in the shell of a roll used as a suction roll there is perforation, in order to direct the pressure difference, created inside the roll by means inside or outside the roll, to the wire and from there to the web.
• the roll according to the invention can also be used as a dryer cylinder, which is shown in Figure 4.
• circular rings are used as the stiffener pieces 19, and are additionally connected by a cylindrical support piece 24.
• the support piece 24 and the stiffener pieces 19 are perforated, so that hot steam can spread evenly over the entire area of the shell 16.
• the support piece 24 extends to a short distance from the installation plate 25, allowing the syphon 27 to be fitted against the inner surface of the shell 16.
• the solid arrows show the spread of the steam inside the dryer cylinder.
• end pieces of the same kind each of which has a cell structure according to the invention.
• the end piece 17 includes a separate inner piece 28, in which there is an internal hole 30 corresponding to the protruding shaft 20, for the attachment of the protruding shaft 20.
• the end plate of the end piece 17 is supported on the inner piece 28 by at least one plate piece 31.
• the various parts of the end piece can be manufactured separately, thus avoiding the casting and machin ⁇ ing of large pieces.
• the parts can even be made in different ways and from different materials. Thus it is possible to take into account, for example, stresses arising from the loading, or surface roughness requirements.
• the end plate is also supported by a second plate piece 32, which further facilitates the manufacture of the end piece.
• the construction in question is hollow, so that the end piece can be filled with insulation 33.
• the insulation is, for example, an extruded foam, which will spread evenly in the end piece and solidify in place.
• the same reference numbers are used for components that are functionally similar.
• FIG. 6a shows the roll according to the invention as a dryer cylinder 10.
• the shell 16 is of a thin-sheet material.
• the end piece 17 is cup-shaped and is welded to the shell 16.
• This an installation plate is unneces ⁇ sary.
• the stiffener structure 19 includes tensionable stiffener rings and heat strips 34 running in the longitudinal direction of the roll. Thus welding is not essential. The heat strips even and boost the distribution of heat. In addition, they increase the axial and annular stiff ⁇ ness of the roll.
• each stiffener ring there is a tensioning arrangement 35, which includes a tensioner screw 37.
• tensioner screws 37 There are suitable flanges 36 in the stiffener ring for the tensioner screws 37.
• At the end of the roll there is also a steam condensate coupling 40, through which steam is first led into the roll and corresponding condensate is removed from the roll 10, for example, with the aid of a syphon 41.
• shells can be created with a maximum diameter of 2500 mm.
• the roll's diameter is 1000 - 5000 mm, preferably 1500 - 4000 mm. This is achieved by using a thin-sheet material in the manufac ⁇ ture of the roll.
• both the shell and the stiffener pieces are preferably laser-cut and laser-welded thin-sheet pieces. Using laser cutting, thin-sheet pieces with accurate dimensions and shape are created, which can be bent to a precise shape. Using laser welding, the thin-sheet pieces can also be attached to each other without deformations . On the other hand, gluing can be used in the attachments. Besides, or instead of laser methods, other suitable methods can be used.
• the shell is preferably made from a single thin-sheet pieces, which is butt-welded.
• the shell is formed of two or more cylindrical pieces.
• the roll according to the invention is considerably lighter than previous rolls.
• the shell is made sufficiently stiff by using a stiffener structure.
• the use of the structure eliminates semi-critical vibration, so that it is possible to manufacture safely smaller or correspondingly larger rolls than before.
• the previous limits set by the manufacturing technique can be avoided, without weight problems. It is then possible to manufacture even very large rolls.
• the roll is highly corrosion-resistant while the new manufacturing method also shortens the delivery time for rolls .
• the transmission of heat through the thin shell is also more efficient than previously.

Landscapes

• Drying Of Solid Materials (AREA)
• Rolls And Other Rotary Bodies (AREA)
• Paper (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=32749273

Family Applications (1)

Country Status (4)

Families Citing this family (2)

Citations (3)

• 2004
  • 2004-07-28 FI FI20045282A patent/FI117013B/sv not_active IP Right Cessation
• 2005
  • 2005-06-22 WO PCT/FI2005/050233 patent/WO2006010795A1/en active Application Filing
  • 2005-06-22 DE DE112005001565T patent/DE112005001565T5/de not_active Withdrawn
  • 2005-06-22 CN CN2005800233208A patent/CN1985046B/zh not_active Expired - Fee Related

Patent Citations (3)

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