A method for treating a Yankee cylinder, where the Yankee cylinder has a cylinder shell made of steel with a ferritic-pearlitic structure. In the disclosed method, the outer surface of the cylinder shell is heat-treated with a laser beam and hardened as a result.

There is provided a method of producing a paper having a grammage according to ISO 536 of 50-250 g/m2, a Gurley value according to ISO 5636-5 of above 15 s and a stretchability according to ISO 1924-3 in the cross direction of at least 8%, said method comprising the steps of: a) providing a pulp, preferably sulphate pulp; b) subjecting the pulp to refining; c) diluting the pulp from step b) and discharging the diluted pulp at a discharge rate to a forming wire to form a paper web, wherein the speed of the forming wire is at least 7 m/min higher or at least 7 m/min lower than the discharge rate; d) pressing the paper web from step c); e) drying the paper web from step d), which drying comprises a step of compacting the paper web in a Clupak unit.

A drying roller includes at least a cylindrical cylinder shell, two caps which are attached to both sides of the cylinder shell, and two journals which are indirectly fastened to the caps by way of a hollow shaft which is connected to the caps or are directly fastened to the caps, wherein the cylinder shell and the caps are welded to one another by way of an annular weld seam. The weld seam has a joint having at least two mutually opposite and parallel flange regions which are mutually spaced apart. A method for manufacturing a drying roller is also described.

A method for producing cellulose-fibre-based drinking straws and a drinking straw. The method comprises: providing a cellulose material, producing at least one aqueous suspension comprising the cellulose material and adding additives to the suspension, homogenizing the aqueous suspension and pre-drying to obtain at least one water-containing non-woven web having a first side and a second side, drying the water-containing non-woven web in a plurality of drying steps to form at least one paper web having a first side and a second side, further processing the paper web or a plurality of paper webs to form a cellulose-fibre-based drinking straw.

At least the first side of the non-woven web is compressed with a line load of 80 kN/m to 500 kN/m before, during or after one of the drying steps and before the further processing to form a cellulose-fibre-based drinking straw.

[Problem]

To provide a method for spraying a chemical solution, including: spraying the chemical solution onto a surface of a dryer roller with a nozzle device reciprocated in the width direction of the dryer roller rotating at a high speed, whereby a sufficient amount of the chemical solution can be remained on the surface of the dryer roller.

[Solution]

The present invention is directed to a method for spraying a chemical solution, including: spraying the chemical solution onto a dryer roller by a nozzle device with the nozzle device reciprocated along a rail extended in the width direction of the dryer roller, in a state that the dryer roller, for guiding wet paper, is being rotated, in a dry part of a paper-making machine, wherein a time T required for the nozzle device to travel one-way is set as 0.4 to 3.0 minutes; a rotational speed Vd of the dryer roller is set as not less than 100 times/min; the number of contacts N that a point Q on the dryer roller surface makes contact with the wet paper during the time T is set as 50 to 400 times; the time T, the rotational speed Vd, and the number of contacts N satisfy the relationship of N=T*Vd; and the total amount of the sprayed chemical solution is set as 0.3 to 500 mg/m.sup.2 as an effective component amount.

A method for producing a Yankee dryer cylinder, or Yankee cylinder, comprises the steps of disposing of a first and of at least a second cylindrical portion of shell. These are made of steel, have the same diameter and are provided with a plurality of grooves at an internal surface. In particular, the portions of shell, at a respective end, are provided of respective flange portions. The method provides to coaxially position the portions of shell up to arrange respective coupling surfaces of the flange portions adjacent one to the other. Then the engagement of the portions of shell is provided by means of a plurality of clamping members, each of which arranged to clamp the adjacent flange portions. Then, it is provided the circumferential welding of the cylindrical portion of the shell that are opposite to the flange portions, and the removal of the clamping members and of the flange portions.

A method for producing a Yankee dryer cylinder, or Yankee cylinder, includes the steps of executing a cylindrical tubular semifinished product made of steel and having a side wall provided with an internal surface and an external surface. A forging step of the cylindrical tubular semifinished product follows for obtaining predetermined thicknesses at the central portion and at the terminal portions of the side wall where the enlarged terminal portions are made. The cylindrical shell is completed executing a plurality of grooves at the internal surface of the cylindrical tubular semifinished product. Then a plurality of longitudinal blind holes are executed at the external surfaces of the enlarged terminal portions of the cylindrical shell. Then, the heads are positioned at each of enlarged terminal portion of the cylindrical shell to which they are fixed by means of studs that pass the blind holes of the shell and respective through holes of which the heads are provided.

[Problem]

To provide a method for spraying a chemical solution, including: spraying the chemical solution onto a surface of a dryer roller with a nozzle device reciprocated in the width direction of the dryer roller rotating at a high speed, whereby a sufficient amount of the chemical solution can be remained on the surface of the dryer roller.

[Solution]

The present invention is directed to a method for spraying a chemical solution, including: spraying the chemical solution onto a dryer roller by two nozzle devices disposed at a certain interval therebetween with the two nozzle devices each reciprocated along a rail extended in the width direction of the dryer roller, in a state that the dryer roller, for guiding wet paper, is being rotated, in a dry part of a paper-making machine, wherein a time T required for the two nozzle devices each to travel one-way is set as 0.2 to 1.5 minutes; a rotational speed Vd of the dryer roller is set as not less than 100 times/min; the number of contacts N that a point Q on the dryer roller surface makes contact with the wet paper during the time T is set as 30 to 250 times; the time T, the rotational speed Vd, and the number of contacts N satisfy the relationship of N=T*Vd; and the total amount of the sprayed chemical solution is set as 0.3 to 500 mg/m.sup.2 as an effective component amount.

[Problem]

To provide a method for spraying a chemical solution, including: spraying the chemical solution onto a surface of a dryer roller with a nozzle device reciprocated in the width direction of the dryer roller rotating at a high speed, whereby a sufficient amount of the chemical solution can be remained on the surface of the dryer roller.

[Solution]

The present invention is directed to a method for spraying a chemical solution, including: spraying the chemical solution onto a dryer roller by two nozzle devices disposed at a certain interval therebetween with the two nozzle devices each reciprocated along a rail extended in the width direction of the dryer roller, in a state that the dryer roller, for guiding wet paper, is being rotated, in a dry part of a paper-making machine, wherein a time T required for the two nozzle devices each to travel one-way is set as 0.2 to 1.5 minutes; a rotational speed Vd of the dryer roller is set as not less than 100 times/min; the number of contacts N that a point Q on the dryer roller surface makes contact with the wet paper during the time T is set as 30 to 250 times; the time T, the rotational speed Vd, and the number of contacts N satisfy the relationship of N=T*Vd; and the total amount of the sprayed chemical solution is set as 0.3 to 500 mg/m.sup.2 as an effective component amount.

A method for operating a heating group subsystem of a machine for the production or treatment of a fibrous web. The heating group subsystem includes a first heating group and a last heating group and at least one additional heating group; in each case having at least one device that is heated with pressurized heating steam. Viewed in a direction of travel, the fibrous web is fed first through the first heating group, then through the at least one additional heating group, and thereafter through last heating group. The steam pressure of the heating steam of the at least one additional heating group is adjusted lower than the respective steam pressure of the heating steam of first heating group and of last heating group.