Clothing for a machine for producing a fibrous web and method for producing a clothing of this type

Abstract

A clothing for a machine for producing a fibrous web, more particularly a paper or cardboard web, is substantially formed from a film-shaped material having a first surface facing the fibrous web and a second surface facing away from the fibrous web. The clothing includes a plurality of through openings each extending along a central axis from the first surface to the second surface. The central axes of at least some of the through openings in the covering enclose an angle with the first surface which differs from 90°. A machine for producing a fibrous web, more particularly a paper or cardboard web, includes the clothing. A method for producing the clothing includes making the through openings in the film-shaped material by using a laser.

Claims

1. A clothing for a machine for producing a fibrous, paper or board web, the clothing comprising: a film-shaped material having a first surface facing the fibrous web, a second surface facing away from the fibrous web, two side edges delimiting the clothing, two edge regions adjacent said two side edges, and a central region disposed centrally between said two side edges; said film-shaped material having a multiplicity of passage openings each extending along a respective central axis from said first surface to said second surface; said central axes of at least some of said passage openings enclosing an angle with said first surface differing from 90°; and said central axis of at least one of said passage openings in one of said edge regions having a greater difference from a 90° angle enclosed with said first surface than said central axis of at least one other of said passage openings in said central region to effect a desired dewatering of the fibrous web.

2. The clothing according to claim 1, wherein said central axes of at least two of said passage openings enclose angles with said first surface differing from each other.

3. The clothing according to claim 1, wherein said central axis of at least one of said passage openings has a directional component oriented parallel to a longitudinal direction of the clothing.

4. The clothing according to claim 1, wherein: said central axes of a plurality of said passage openings have a directional component oriented parallel to a longitudinal direction of the clothing; and said directional components of said central axes of most or all of said plurality of said passage openings point in an identical direction.

5. The clothing according to claim 1, wherein said central axis of at least one of said passage openings has a directional component oriented parallel to a transverse direction of the clothing.

6. The clothing according to claim 1, wherein: said central axes of a plurality of said passage openings have a directional component oriented parallel to a transverse direction of the clothing; and said directional components of said central axes of approximately half of said plurality of said passage openings point in a direction opposite to said directional components of said central axes of a remainder of said plurality of said passage openings.

7. The clothing according to claim 6, which further comprises: a first side edge and a second side edge delimiting the clothing; and said passage openings having said central axes with directional components oriented parallel to the transverse direction and all pointing in an identical direction being disposed closer to said first side edge than said passage openings having said central axes with directional components oriented parallel to the transverse direction and pointing in the opposite direction.

8. The clothing according to claim 1, wherein said edge regions are viewed in the transverse direction of the clothing.

9. The clothing according to claim 1, wherein said clothing is a forming clothing or wire.

10. A machine for producing a fibrous, paper or board web, the machine comprising a clothing according to claim 1.

11. The machine according to claim 10, which further comprises a forming section of the machine, the clothing being installed in said forming section.

12. The machine according to claim 10, wherein: said central axes of a plurality of said passage openings of the clothing installed in the machine have directional components oriented parallel to the longitudinal direction of the clothing; and said directional components of said central axes of most or all of said plurality of passage openings point in a direction opposite to a running direction of the clothing.

13. A method for producing a clothing for a machine for producing a fibrous, paper or board web, the method comprising the following steps: providing a film-shaped material having a first surface facing the fibrous web, a second surface facing away from the fibrous web, two side edges delimiting the clothing, two edge regions adjacent the two side edges, and a central region disposed centrally between the two side edges; using a laser to introduce a multiplicity of passage openings in the film-shaped material, each of the openings extending along a respective central axis from the first surface to the second surface; orienting the central axes of at least some of the passage openings to enclose an angle with the first surface differing from 90°; and orienting the central axis of at least one of the passage openings in one of the edge regions to have a greater difference from a 90° angle enclosed with the first surface than the central axis of at least one other of the passage openings in the central region to effect a desired dewatering of the fibrous web.

14. The method according to claim 13, which further comprises using mirror optics functionally connected to the laser to introduce at least two of the passage openings into the film-shaped material at angles differing from one other and enclosing angles differing from 90° with the first surface.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 shows a fragmentary, diagrammatic, perspective view of a prior art film-like material of a clothing being produced;

(2) FIGS. 2 and 3 show cross-sectional views of the prior art film-like material;

(3) FIG. 4 shows a perspective view of the clothing;

(4) FIG. 5 shows a cross-sectional view of a section of the film-like material along the longitudinal direction of the clothing according to the invention;

(5) FIG. 6 shows a cross-sectional view of this section of the film-like material along the transverse direction of the clothing according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 5 illustrates, schematically, a cross-sectional view of a section of the film-like material 12 along the longitudinal direction LR of the clothing 10 according to the invention. The clothing 10 or the film-like material 12 has a first surface 14 which, in the intended use of the clothing 10, faces the fibrous web forming on the same, and a second surface 16 opposite the first surface 14. In addition, it can be seen that, between the first surface 14 and the second surface 16, six passage openings 24 extend through the film-like material 12. The dewatering of the fibrous suspension for forming the fibrous web can be carried out through said passage openings 24. Each of the passage openings 24 has a respective rectilinear central axis 32 which, in the figures, is illustrated dashed. The walls of the passage openings 24 extend rotationally symmetrically around the corresponding central axis 32. In the present exemplary embodiment, the passage openings 32 are all cylindrical, but could also be conical, i.e. widen toward the first surface 14 and/or second surface 16.

(7) The two passage openings 24 illustrated on the left in FIG. 5 have central axes 32 which extend substantially orthogonally to the first surface 14. This thus corresponds to the prior art described with regard to FIG. 2.

(8) As opposed to this, the two passage openings 24 illustrated in the middle in FIG. 5 have central axes 32 which, with respect to the first surface, enclose an angle which, as can be seen, differs from 90°. In particular, the central axes 32 of these two passage openings 24 are inclined with respect to the first surface 14 such that the central axes 32 have a directional component RK which is oriented parallel to the longitudinal direction LR of the clothing 10. The directional component RK also points in the same direction as the running direction MD of the clothing 10 in the intended use. The dynamic forces acting during operation of the clothing 10 lead to a congestive action occurring in the central two passage openings 24, so that in the latter, the dewatering is slowed down as compared with the two left passage openings 24, of which the central axes 32 are aligned substantially orthogonally to the first surface 14,

(9) The two passage openings 24 illustrated on the right in FIG. 5 also have central axes which, with respect to the first surface, enclose an angle which, as can be seen, differs from 90°. Likewise, the central axes 32 of these two passage openings 24 are inclined with respect to the first surface 14 such that the central axes 32 have a directional component RK which is oriented parallel to the longitudinal direction LR of the clothing 10. However, as distinct from the two passage openings 24 illustrated in the middle in FIG. 5, the directional component RK of these two passage openings 24 points in the opposite direction to the running direction MD of the clothing 10 in the intended use. The dynamic forces occurring during operation of the clothing 10 lead to a suction action occurring in the two right-hand passage openings 24, so that the dewatering is accelerated as compared with the two passage openings 24 on the left, of which the central axes 32 are oriented substantially orthogonally to the first surface 14, and in particular as compared with the two central passage openings 24.

(10) FIG. 6 illustrates, schematically, a cross-sectional view of a section of the film-like material 12 along the transverse direction QR of the clothing 10 according to the invention. Visible in FIG. 6 are five passage openings 24, which each extend between the first surface 14 and the second surface 16 through the film-like material 12. Each of the passage openings 24 again has a respective rectilinear central axis 32. The walls of the passage openings 24 extend substantially rotationally symmetrically around the corresponding central axis 32.

(11) The passage opening 24 illustrated in the middle in FIG. 6 has a central axis 32, which extends substantially orthogonally to the first surface 14. This thus corresponds to the prior art described with regard to FIG. 2.

(12) As opposed to this, the two passage openings 24 illustrated on the left in FIG. 6 have central axes 32 which, with respect to the first surface 14, enclose an angle which, as can be seen, differs from 90°. In particular, the central axes 32 of these two passage openings 24 are inclined with respect to the first surface 14 such that the central axes 32 have a directional component RK which is oriented parallel to the transverse direction QR of the clothing 10. The directional component RK for these two passage openings 24 points to the left in FIG. 6.

(13) The two passage openings 24 illustrated on the right in FIG. 6 also have central axes 32 which enclose an angle with respect to the first surface which, as can be seen, differs from 90°. Likewise, the central axes 32 of these two passage openings 24 are inclined with respect to the first surface 14 such that the central axes 32 have a directional component RK which is oriented parallel to the transverse direction QR of the clothing 10. However, as distinct from the passage opening 24 illustrated on the left in FIG. 6, the directional component RK of these two passage openings 24 points in the opposite direction, i.e. to the right in FIG. 6.

(14) As can be gathered further from FIG. 6, the inclination of the central axes 32 of the two outermost passage openings 24 to the orthogonal to the first surface 14 is greater than the inclination of the central axes 32 of the two passage openings 24 which are each arranged between the central passage opening 24 and the two outer passage openings 24. The steeper the inclination, the greater the channel length of the corresponding passage opening 24 is and the more slowly or more gently the dewatering is carried out. It may be advantageous that the passage opening 24 shown in the middle in FIG. 6, of which the central axis 32 is oriented substantially orthogonally to the first surface 14, is arranged in a central region which is located in the middle between the two side edges 34 and 36 (see FIG. 3) of the clothing. In this way, the dewatering characteristics can be provided substantially symmetrically relative to the transverse profile of the clothing 10.

(15) It goes without saying that the examples illustrated in FIGS. 5 and 6 are intended merely to illustrate the basic principle of the present invention. The adjustment of the inclination of the central axes of the individual passage openings relative to the first surface can be carried out differently over the clothing as required, in order to obtain an optimal fibrous web that is matched to the needs.

LIST OF DESIGNATIONS

(16) 10 Clothing 12 Film-like material 14 First surface 16 Second surface 18 Elevation 20 Depression 22 Laser 24 Passage opening 26 Controller 28 Line 30 Pulse of radiation 32 Central axis 34 First side edge 36 Second side edge LR Longitudinal direction QR Transverse direction RK Directional component MD Running direction