WO2011120763A1

WO2011120763A1 - Milling arrangement

Info

Publication number: WO2011120763A1
Application number: PCT/EP2011/053413
Authority: WO
Inventors: Oliver Lüdtke
Original assignee: Voith Patent Gmbh
Priority date: 2010-04-01
Filing date: 2011-03-08
Publication date: 2011-10-06
Also published as: DE102010003582A1

Abstract

The invention relates to a milling arrangement for milling aqueously suspended pulp fibres (6) between two milling surfaces (1, 2) which form a milling nip, move relative to one another and have milling strips (3, 4) and grooves (5, 6) extending between said strips, wherein at least one milling surface (1) rotates about an axis of rotation (7) passing vertically through the centre of the milling surface (1), and the milling strips (3, 4) extend with a main direction component radially with respect to the axis of rotation (7). It should be possible here, even with a varying long fibre content, to achieve efficient milling and minimum wear in that the width of the milling strips (3, 4) of at least one milling surface (1, 2) increases radially outwardly and/or the milling strips (4) of a milling surface (2) extend rectilinearly and the inclination of the milling strips (3) of the other milling surface (1) increases outwardly with respect to the radial (8) starting from the axis of rotation (7).

Description

grinder assembly

The invention relates to Mahlanordnungen for grinding aqueous pulp fibers suspended between two Mahlspalt forming, pressed against each other and moving relative grinding surfaces with Mahlleisten and intervening grooves, wherein at least one grinding surface rotates about a perpendicular passing through the middle of the grinding surface axis of rotation and the Mahlleisten with a significant directional component extending radially to the axis of rotation.

It has long been known to use pulp fibers, i. Fresh pulp and / or

To mill waste paper fibers in order to achieve the desired properties, in particular in terms of strength, formation and surface of the fibrous web produced therefrom.

In the case of the refiners usually used in the process, the Mahlleisten

Knife called and formed the grinding surfaces of Mahlgarnituren.

The refiner can be designed as a disc refiner or cone refiner. To achieve the desired fiber properties, in particular the freeness, the grinding sets must be optimally adapted to the pulp to be treated, also to prevent excessive wear of the sets.

However, this adaptation is particularly problematic in the treatment of

Waste paper fibers, as their content of long fibers can vary considerably.

The object of the invention is therefore to ensure efficient grinding with the least possible wear, in particular with varying long fiber content.

According to the invention, this object is achieved in that the width of the grinding strips increases at least one, in particular both grinding surfaces radially outward. there It is advantageous if the grinding surfaces are designed differently, in particular if the grinding bars of a grinding surface are straight and the grinding bars of the other grinding surface are at least partially odd. The increasing width of the grinding bars has a very positive effect on the

Grinding performance and wear out. In conjunction with the different grinding surfaces, in particular the even and odd grinding bars, a large cutting edge length and a large hunting surface can be realized.

In the interest of continuous transitions, it is advantageous if the odd grinding bars have no straight sections.

Alternatively or additionally, it is advantageous if the grinding bars of a grinding surface are straight and the inclination of the grinding bars of the other grinding surface to the radial axis extending from the rotation axis increases radially outwards.

This orientation of the grinding bars increases the cutting angle radially outward, which improves the efficiency of grinding independent of the long fiber content. This is due, in particular, to the fact that different fibers often also require different cutting angles and, as a result of the invention, a cutting angle range is realized.

The cutting angle is formed by the two grinding edges of the sweeping Mahlleisten the opposing grinding surfaces in their relative movement.

The straight Mahlleisten form between them straight grooves, which one

Return flow of the suspension radially inward counteract only little flow resistance. In this case, the straight Mahlleisten should be inclined about 5 to 15 ° to the radial and the inclination of the odd Mahlleisten the Radial inside in the range between 5 and 15 ° and radially outside between 40 and 55 °. Furthermore, depending on the nature of the composition of matter, it may be advantageous if the inclination of the odd grinding bars to the radial increases continuously outward, or else the inclination of the odd grinding bars to the radial increases outwardly abruptly.

The abrupt change in direction of the odd Mahlleisten can by a

Interruption of the same or done by a kink.

Between these abrupt changes of direction, it may be advantageous if the inclination of the odd grinding bars to the radial outward sections remains constant or if the inclination of the odd grinding bars to the radial changes outwardly in sections, preferably continuously increases.

For a homogeneous pattern of the grinding bars, it is advantageous if the width of the grinding bars increases continuously radially outwards.

In the interests of an approximately equal loading of the grinding bars of both grinding surfaces, the grinding bars of both grinding surfaces in the respective crossing region should be about the same width when sweeping the Mahlleisten the opposite grinding surfaces and the width preferably between 1, 2 and 4 mm.

The intersection of intersecting grinding strips, often referred to as Jagenberg surface, amounts to a total of about 18 - 28% of the total grinding surface and essentially influences the hydraulic counterforce in the grinding gap.

According to the requirements and circumstances, it may be advantageous if both grinding surfaces rotate about the same axis of rotation in the opposite direction or at different speeds in the same direction or rotate only one grinding surface.

In general, but especially in cases where only one grinding surface rotates, the width of the grooves of the rotating grinding surface should be almost radially outward which helps to increase the velocity of the fiber suspension from inside to outside.

In contrast, the width of the grooves of the non-rotating grinding surface should increase radially outward and preferably be radially inwardly between 2 and 4 mm and radially outside between 3 and 5 mm.

This allows a return flow of the fiber suspension in these grooves as far inward as possible. With regard to the treatment of waste paper fibers, it has proven to be advantageous if the angle of intersection of the mutually moved by Mahlleisten radially inward is not less than 10 °, preferably between 10 and 20 ° and radially outside between 35 and 60 °. By the mentioned backflow of the fiber suspension wins the radially outer region of importance, which is why there is a fibrillierender cutting angle.

In order to avoid large pressure fluctuations in the grinding gap in the radial direction, at least one, preferably all grinding bars should extend without interruption radially as far as possible over the entire grinding surface.

However, in the case of very large grinding surfaces, it can be of advantage if at least one, preferably all the grinding strips of at least one grinding surface extend radially only over a partial section of the grinding surface.

In the interests of a symmetrical and compact arrangement of the grinding bars, at least one, preferably one rotating grinding surface should have at least two annular rows of grinding bars arranged radially one behind the other. It may be advantageous if between the radial one behind the other

arranged rows of Mahlleisten an annular groove exists or the radial Limiting the Mahlleisten inclined to the circumferential direction of the rotating grinding surface.

The invention will be explained in more detail below with reference to several exemplary embodiments. In the attached drawing shows:

FIG. 1: a partial cross section through a disk refiner;

Figure 2: a Mahlgarnitur 14 for a stator 16;

Figure 3: a Mahlgarnitur 13 for a rotor 15;

Figure 4: another Mahlgarnitur 13 for a rotor 15;

Figure 5: the cutting angle 9 between two opposite Mahlleisten 3.4; Figure 6 + 7: a grinding surface 1 with two annular rows of odd

Grinding bars 3.

The grinding arrangement according to FIG. 1 is formed by a fixed stator 16 and a rotor 15 rotating about a rotation axis 7. While on the stator 16 a Mahlgarnitur 14 to form the non-rotating grinding surface 2 is releasably secured by screws 1 1, a differently designed Mahlgarnitur 13 is releasably attached to the rotor 15 to form the rotating grinding surface 1. In this case, the two circular grinding surfaces 1, 2 parallel to each other, wherein the distance between them is shown exaggerated.

Both Mahlgarnituren 13,14 have on the side of their grinding surfaces 1, 2 a plurality of substantially radially extending Mahlleisten 3.4, so that the grinding surfaces 1, 2 of these Mahlleisten 3.4 and the grooves 5,6 between them are formed.

In the example shown here, the fiber suspension S to be grounded passes through the center of the stator 16 into the grinding gap between the two grinding sets 13, 14. The fiber suspension S passes the cooperating grinding surfaces 1, 2 radially outward, accumulates in the adjoining annular space 10th

While a part of the fiber suspension S this annulus 10 by a

Leaves outlet, the other part of the fiber suspension flows through the S Grooves 6 of the non-rotating grinding surface 2 back through a portion of their length.

Not shown are the means known per se, with which a force is generated to press the two Mahlgarnituren against each other.

The cross section of Mahlleisten 3,4, also called knife, is generally approximately rectangular, but there are other forms. The top of Mahlbar 3,4, so the surfaces carrying the grinding edges, the respective

Complete grinding set 13,14 in the direction of counter set, are in the

Radial plane.

The running between the grinding bars 3, 4 grooves 5,6 also have an approximately rectangular cross-section and serve as flow channels for the

Fiber suspension S. The groove depth 12 is usually between 2 and 20 mm, preferably between 5 and 8 mm.

It is essential here that the grinding bars 4 of the stationary grinding surface 2 are straight and the inclination of the grinding bars 3 of the rotating grinding surface 1 to the radial axis 8 proceeding from the axis of rotation 7 increases to the outside.

This ensures that the intersection angle 9 between the

opposite grinding edges of Mahlleisten 3,4 when sweeping radially outward from about 10 to 20 ° inside increased up to 60 °. The angle of intersection 9 results, as can be seen in FIG. 5, when the grinding edges, which are axially opposite one another with respect to the axis of rotation 7, are moved past one another during the rotation of the grinding surface 1. Due to the range of cutting angles 9 can also

Raw materials with varying long fiber content are treated effectively. The intersecting Mahlleisten 3.4 in this case form the Jagenbergfläche 17th

In this case, the width of the Mahlleisten 3.4 radially outward preferably continuously increases, which increases the allowable edge load and thus the Mahlleistung. In the interest of the largest possible number of Mahlleisten 3,4 is their Width radially inward in the range of 0.8 and 1, 7 mm, while the width is radially outside between 3 and 6 mm.

For the equilateral treatment of the fibers, it is advantageous if the axially opposite grinding strips 3,4 of both grinding surfaces 1, 2 in the respective

Junction (see Figure 5) are about the same width. The same width of the intersecting Mahlleisten 3.4 ensures a local balance of power.

In addition, it is advantageous if all Mahlleisten 3.4 are inclined to the radial 8. While the odd Mahlleisten 3 of the rotating grinding surface 1 is inclined against the direction of rotation to the radial 8, the straight Mahlleisten 4 of the non-rotating grinding surface 2 are inclined about 5 to 15 ° in the direction of rotation of the opposite grinding surface 1 to the radial 8.

In contrast, the inclination of the odd grinding strips 3 to the radial 8 inside is in the range between 5 and 15 ° and radially outside between 40 and 50 °.

As can be seen in the non-rotating grinding surface 2 shown in FIG. 2, the width of the grooves 6 of the non-rotating grinding surface 2 increases radially outward and is preferably radially inwardly between 2 and 4 mm and radially outside between 3 and 5 mm. This supports the already mentioned backflow of the fiber suspension S as far as possible inwards.

In contrast, the width of the grooves 5 of the rotating grinding surface 1 according to Figures 3, 4 and 6.7 remains radially outwardly almost constant.

In the embodiment according to FIG. 3, the inclination of the odd grinding strips 3 to the radial 8 increases continuously towards the outside.

In contrast, the inclination of the odd grinding bars 3 to the radial 8 to the outside in Figure 4 at here abruptly increases, for example, two break points.

At these break points, the odd grinding bars 3 can also be interrupted.

Between the break points, the inclination of the odd grinding strips 3 to the radial 8 to the outside, as seen in Figure 4, remain constant in sections. But it is also possible that the inclination of the odd Mahlleisten 3 changed to the radial 8 between these break points.

While the milling strips 3, 4 described hitherto extend radially approximately over the entire grinding surface 1, 2, they are limited in FIGS. 6 and 7 to a radial section of the grinding surface 1.

The odd grinding strips 3 are arranged in two annular rows arranged radially one behind the other. As can be seen in FIG. 7, an annular groove 18 can run between these rows. However, it may also be advantageous that the radial boundary of the grinding bars 3, 4 runs inclined relative to the circumferential direction of the rotating grinding surface 1, so that the groove 18 extending between the rows, as shown in FIG. 6, deviates from the ring shape.

Claims

claims

1 . Grinding arrangement for grinding aqueous suspended pulp fibers (S) between two grinding surfaces (1, 2) forming a grinding gap and moving relative to each other with grinding bars (3, 4) and grooves (5, 6) extending therebetween, at least one grinding surface (1) about a perpendicularly through the middle of the grinding surface (1) going rotation axis (7) rotates and the Mahlleisten (3,4) with a significant directional component radially to the axis of rotation (7), characterized in that the width of the Mahlleisten (3,4) at least one grinding surface (1, 2) increases radially outward.

2. grinding arrangement according to claim 1, characterized in that the width of the Mahlleisten (3, 4) of both grinding surfaces (1, 2) increases radially outward.

3. grinding arrangement according to claim 1 or 2, characterized in that both Mahflächen (1, 2) are formed differently, wherein preferably the Mahlleisten (4) of a grinding surface (2) run straight and the Mahlleisten (3) of the other grinding surface (1) at least partially odd.

4. grinding arrangement according to one of the preceding claims, characterized

characterized in that the odd grinding strips (3) of the other grinding surface (1) have no straight sections.

5. Grinding arrangement for grinding of aqueous suspended pulp fibers (S) between two Mahlspalt forming and relatively moving grinding surfaces (1, 2) with Mahlleisten (3,4) and extending therebetween grooves (5,6), wherein at least one Mahlfläche ( 1) about a perpendicular through the center of the grinding surface (1) going rotation axis (7) rotates and the Mahlleisten (3,4) with a significant direction component radially to the axis of rotation (7), in particular one of the preceding claims, characterized in that the Mahlleisten (4) of a grinding surface (2) run straight and the Increase of the Mahlleisten (3) of the other grinding surface (1) from the axis of rotation (7) outgoing radials (8) outwardly increases.

6. grinding arrangement according to one of claims 3 to 5, characterized in that the straight Mahlleisten (4) about 5 to 15 ° to the radial (8) are inclined.

7. grinding arrangement according to one of claims 3 to 6, characterized in that the inclination of the odd grinding strips (3) to the radial (8) inside in the range between 5 and 15 ° and radially outside between 40 and 55 °.

8. grinding arrangement according to one of claims 3 to 7, characterized in that the inclination of the odd grinding strips (3) to the radial (8) continuously increases to the outside.

9. grinding arrangement according to one of claims 3 to 7, characterized in that the inclination of the odd grinding strips (3) to the radial (8) increases outwardly abruptly.

10. grinding arrangement according to claim 9, characterized in that the inclination of the odd grinding strips (3) to the radial (8) to the outside sections remains constant.

1 1 .Mahlanordnung according to claim 9 or 10, characterized in that the inclination of the odd grinding strips (3) to the radial (8) outwardly changed in sections, preferably continuously increases.

12. grinding arrangement according to one of the preceding claims, characterized

characterized in that the width of the Mahlleisten (3,4) increases continuously radially outward.

13. grinding arrangement according to one of the preceding claims, characterized

characterized in that the Mahlleisten (3,4) of both grinding surfaces (1, 2) in the respective Crossing area are about the same width and the width is preferably between 1, 2 and 4 mm.

14. grinding arrangement according to one of the preceding claims, characterized

characterized in that both grinding surfaces (1, 2) rotate about the same axis of rotation (7) in the opposite direction or at different speeds in the same direction.

15. grinding arrangement according to one of claims 1 to 13, characterized in that only one grinding surface (1) rotates.

16. grinding arrangement according to one of the preceding claims, characterized

in that the width of the grooves (5, 6) of the rotating grinding surface (1) remains constant radially outward.

17. grinding arrangement according to claim 15 or 16, characterized in that the width of the grooves (4) of the non-rotating grinding surface (2) radially outwardly increases and preferably radially inwardly between 2 and 4 mm and radially outside between 3 and 5 mm ,

18. grinding arrangement according to one of the preceding claims, characterized

in that the angle of intersection (9) of the grinding bars (3, 4) moved past one another radially inward is not less than 10 °, preferably between 10 and 20 ° and radially outside less than 60 °.

19. Mahlanordnung must one of the preceding claims, characterized

characterized in that at least one, preferably all Mahlleisten (3,4) without interruption extend radially as far as possible over the entire grinding surface (1, 2).

20. grinding arrangement according to one of the preceding claims, characterized

characterized in that at least one, preferably all, grinding strips (3, 4) at least one grinding surface (1, 2) radially only over a portion of the

Grinding surface (1, 2) extend.

21. Grinding arrangement according to claim 20, characterized in that at least one, preferably a rotating grinding surface (1, 2) has at least two radially successively arranged annular rows of grinding strips (3,4).

22. grinding arrangement according to claim 21, characterized in that between the radially successively arranged rows of Mahlleisten (3,4) an annular groove (18) exists.

23. grinding application according to one of the preceding claims, characterized

characterized in that the radial boundary of the grinding bars (3,4) for

Circumferentially inclined.