Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B29/00—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents
  • B24B29/02—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents designed for particular workpieces
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
  • D21G1/00—Calenders; Smoothing apparatus
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
  • D21G9/00—Other accessories for paper-making machines
  • D21G9/0009—Paper-making control systems
  • D21G9/0045—Paper-making control systems controlling the calendering or finishing

Definitions

• the invention relates to a method for profiling in CD-direction the surface qualities of a fibrous web, such as a paper or board web, to be manufactured/treated in a paper/board machine or in a finishing machine.
• thermo roll smoothness of a pressing surface
• Replication effect is known from chill rolls, during the wearing of which the calendered gloss falls by several percentage points in terms of Hunter gloss.
• SC- paper among others, it has been experimentally found out, for example, that the roughness change of a thermo-roll surface from Ra-number 0.1 ⁇ m to number 0.4 ⁇ m degrades the paper's subsequent Hunter gloss by as much as 10 percentage points.
• a method of the invention comprises controlling the CD-directed surface roughness of at least a single pressing element, working on a fibrous web in a nip or treatment zone, by polishing or roughening the surface of the element selectively in various positions along CD-direction.
• the method enables a relatively simple control over the cross-profile regarding surface qualities, such as the gloss and smoothness of a fibrous web to be produced or treated, by polishing and/or roughening a roll in contact with the fibrous web selectively in various positions along CD- direction (profiling the surface roughness).
• the machining grinding of a roll or belt is preferably performed without removing the roll or belt from the machine, by using for example a crosswise traversing grinding device or laser polishing. It is within the scope of the invention to treat just a portion of the roll/belt surface, or the surface can be treated over its entire lateral dimension to a predetermined crosswise roughness profile.
• the machining/grinding can also be performed in separation from the machine, which is common practice today. What is essential is that the roughness profile in CD-direction is under control and used for controlling (profiling) the surface quality of paper.
• the Ra-roughness profile of a surface to be machined is selected such that discrepancies in Ra-roughness between various parts of the surface are not less than 0.01 ⁇ m and not more than 1.0 ⁇ m.
• the method is apt for correcting profile defects of permanent nature, for example for a more intensive calendering of dried-up web edges whenever a sufficient increase of the nip pressure profile is ruled out or undesirable. It is generally useful in situations which call for a local permanent type higher level of smoothness or gloss and which deny the use of a higher line load or temperature.
• the method provides a new control variable (degree of freedom) for profile "adjustment".
• the method can be applied in a calender, a metal belt calender, a cylinder dryer section, a Yankee cylinder dryer, a CondeBelt dryer, etc.
• thermo rolls placed against the opposite sides of paper are deliberately ground to pre-selected and possibly unequal roughness levels.
• thermo rolls present upstream of the deflector nip can be polished for a higher level and the thermo rolls downstream of the deflector nip can be polished to a lower roughness level.
• the arrangement enables a control over the one- sidedness of gloss (and to some extent smoothness) without proportioning the one-sided ness of temperature or wetting.
• the method can be applied for multi-nip calenders (Super-, OptiLoad) or soft and machine calenders.
• a method of the invention enables the use of a preferably laterally movable grinding device, which is placed in a liquid-filled chamber, said method comprising the use of a backing element, which is on the opposite side of a belt and which is cooled by means of a fluid flow for effecting the belt grinding at a substantially constant temperature.
• Fig. 1 is a schematic side view, showing one metal-belt grinding device of the invention, which is apt for use in a method of the invention,
• Fig. 2 is a schematic side view, showing a grinding device of the invention in a second embodiment
• Fig. 3 is a schematic side view, showing a grinding device of the invention in a third embodiment
• Fig. 4 is a schematic side view, showing a grinding device of the invention in a fourth embodiment.
• Fig. 5 is a schematic plan view, showing a grinding device of the invention in a fifth embodiment.
• the grinding device according to a first embodiment of the invention comprises support rolls 8, around which a belt 9 to be ground, disengaged from a fibrous web processing mechanism, is adapted to circle, and a grinding unit 3 disposed on one side of the belt 9 and a backing table 4 disposed on the other side of the belt.
• the grinding unit 3 comprises a cylinder chamber 10, its internal cavity 6 containing a grinding tool 5 which is adapted to travel crosswise of the metal belt 9 for oscillation along guide bars 5b.
• the grinding tool 5 includes a grindstone 5a with a horizontal axis of rotation.
• the cavity 6 is filled with a liquid, e.g.
• the cavity 6 has its pressure preferably within the range of 1-20 bars, conveniently at a pressure of about 10 bars.
• the backing table 4 is also provided with a cooling-fluid filled cavity, said cooling fluid being preferably a liquid or a liquid mixture, e.g. water or an aqueous liquid mixture.
• the fluid is delivered in through an inlet 7a and out through an outlet 7b.
• the fluid pressure existing in the backing table's cavity is preferably within the range of about 0 to about 1 bar.
• the device operates as follows.
• the support rolls 8 are used for tensioning and driving the belt 9.
• the cylinder chamber 10 is used for pressing the belt 9 against the precision- ground backing table 4, which is preferably provided with small aspiration holes for pressing the belt tightly against the table.
• the belt is proceeded slowly in a space between the cylinder chamber 10 and the backing table 4 for grinding the belt all over or at desired crosswise spots in order to effect a CD-directed profiling.
• the temperature of a belt presently in grinding can be maintained equal on either side of the belt, e.g. at a temperature of +23°C. Being ground in a chamber filled with water or other liquid, the belt neither heats up nor vibrates. Moving the grindstone back and forth can be implemented e.g. by way of an NC-control, thus enabling the use of various compensatory contours.
• the backing table 4 has its top provided with capillary passages 15, whereby the liquid present in the backing table's interior chamber is able to flow into an interspace between the belt 9 presently in grinding and the top surface of the backing table for providing a liquid bearing system.
• the cylinder chamber 10 has its bottom edge provided with gaskets 14. A discharge line downstream of the outlet 6b is provided with a control valve 11.
• the cylinder chamber 10 is made movable in vertical direction by means of uprights 12, e.g. by the action of a cylinder 13.
• the grinding tool 5 is adapted to travel along guide bars 5b and 5c in oscillation crosswise of the metal belt.
• a third exemplary embodiment for a grinding device of the invention wherein the backing table comprises a counter-roll 16 provided with an internal cooling fluid circulation. Atop the belt 9, on either side of the grinding unit 3 there are provided auxiliary rolls 17 for guiding the belt along the surface of the counter-roll.
• a fourth exemplary embodiment wherein the grinding tool 5a is a face grinder.
• a fifth exemplary embodiment wherein the cylinder chamber 10 itself travels in oscillation crosswise of the belt 9 presently in grinding, whereby the fluid pressure inside the chamber 10 can be higher than those in the preceding examples, in which both the cylinder chamber and the backing table or the counter-roll extend across or beyond the entire width of the belt, and it is only the grinding tool present inside the cylinder chamber which travels in lateral direction.
• the backing table or the counter-roll can be provided with durable ceramic coatings.
• the belt's outermost edge can be left unfinished and the belt can be trimmed to a correct width only after finishing it by grinding.
• the grinding can be performed e.g. in such a manner that the belt is subjected first to traditional grinding and then to finishing by means of a grinding device of the invention.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
• Grinding Of Cylindrical And Plane Surfaces (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

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Family Applications (1)

Country Status (4)

Cited By (3)

Families Citing this family (4)

Citations (4)

Family Cites Families (1)

• 2006
  • 2006-02-01 FI FI20065077A patent/FI120884B/fi not_active IP Right Cessation
• 2007
  • 2007-01-17 WO PCT/FI2007/050022 patent/WO2007088241A1/en active Application Filing
  • 2007-01-17 EP EP20070700287 patent/EP1981684B1/en active Active
  • 2007-01-17 CN CN2007800032621A patent/CN101374634B/zh active Active

Patent Citations (4)

Non-Patent Citations (1)

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