Blade Element

Abstract

To improve wear of a pulverization part positioned close to a feed section of a blade element.SOLUTION: A blade element for a pulverization device (1) which pulverizes a fiber material is provided. The blade element includes at least one pulverization section (22) involving a pulverization part (20, 24, 25, 26) and a free space (21) between the pulverization parts and at least one feed section (23) extending at least partially in a longer direction (X) of the blade element (4, 8). Each feed section (23) aims to feed a fiber material to each pulverization section (22). The pulverization part has a first size (d20a, d20b, d20c, d24a, d24b, d24c) extending in a circumferential direction of the blade element and a second size (e20a, e20b, e20c, e24a, e25a, e26a) extending in a longer direction (X) of the blade element. At the same longitudinal (X) position of the blade element (4, 8), the first size of the pulverization part is constituted so as to increase in the circumferential direction (C) of the blade element toward the feed section of the blade element.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a comminuting device for comminuting fibrous material, in particular to a blade element for a comminuting device for comminuting fibrous material. [Background technology]

[0002] The refiner for refining a fibrous material and the disperser for dispersing a fibrous material are grinding devices for grinding a fibrous material. The material is ground between two opposing grinding elements, at least one of which is rotating. A blade element applicable to said grinding device comprises a grinding surface for grinding the fibrous material, the grinding surface comprising at least one grinding section comprising a grinding portion and a free space between the grinding portions, and at least one feed section extending at least partially in the direction of the longitudinal axis of the blade element for feeding the fibrous material to the at least one grinding portion. Summary of the Invention [Problem to be solved by the invention]

[0003] The problem with this type of blade element is, inter alia, the high wear rate of the grinding section which is located next to the feed section and which is the first to come into contact with the fibrous material fed to the feed section. In rotatable grinding elements, these grinding sections are on the side of the grinding section facing the direction of rotation of the rotatable grinding element, and in stationary grinding elements, therefore, on the side of the grinding section facing in the opposite direction to the direction of rotation of the rotatable grinding element. The increased wear rate of said grinding sections is due to the strong turbulence of the fiber-containing material over the grinding sections which are located close to the feed section. This increased wear is especially noticeable as wear of the tops of the grinding sections and rounding of the grinding sections, which reduces the operating efficiency of the blade element. [Means for solving the problem]

[0004] The object of the present invention is to provide a new blade element for a comminuting device for comminuting fibrous material and a new comminuting device for comminuting fibrous material.

[0005] The invention is characterized by the features of the independent claims.

[0006] The invention is based on the idea of ​​increasing the strength and wear resistance of the blade elements close to their feed section.

[0007] The advantage of this solution is an extended operating life of the grinding part of the blade element which is located next to or close to the feed section, whereby satisfactory operating properties of the grinding surface of the blade segment can be maintained for longer.

[0008] Some embodiments of the invention are disclosed in the dependent claims. [Brief description of the drawings]

[0009] The present invention will now be described in more detail below with reference to preferred embodiments with reference to the accompanying drawings. [Figure 1] FIG. 1 is a schematic cross-sectional view of a cone-shaped crushing device. [Diagram 2] FIG. 2 is a schematic partial cross-sectional view of the refiner stator and rotor. [Diagram 3] FIG. 3 is a schematic plan top view of a refiner blade element. [Figure 4] FIG. 4 is a schematic plan top view of a refiner blade element. [Diagram 5] 5 is a schematic top view of a blade element of a disperser. For clarity, the drawings show some embodiments of the invention in simplified form. Like reference numerals refer to like elements in the figures. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] FIG. 1 shows a schematic side view of a cross section of a cone-shaped grinding device 1. The grinding device 1 can be used for grinding fibrous materials, such as wood materials containing lignocellulose or other fibrous materials suitable for use in the manufacture of paper or paperboard. The grinding device 1 shown in FIG. 1 is of the cone type with cone-shaped grinding elements, but grinding devices with disk-shaped, cone-shaped or cylindrical grinding elements can also be used in the same way as in the examples here. In general, the grinding device comprises at least two substantially oppositely positioned grinding elements, at least one of which rotates, and a grinding gap formed between each of the two substantially oppositely positioned grinding elements. In the following, a grinding device with only one rotatable grinding element is described.

[0011] The crushing device 1 of Figure 1 comprises a frame 2 and a stationary, fixed crushing element 3, i.e. a stator 3, supported by the frame 2. The frame 2 provides a body for the stator 3, unless the stator 3 comprises a separate body fixed to the frame 2 of the crushing device 1.

[0012] The stator 3 comprises one or more stator blade elements 4 comprising grinding sections and free spaces or gaps between the grinding sections. The grinding sections are protrusions that protrude from the substrate of the respective blade element and are configured to exert a grinding effect on the fibrous material to be treated, i.e. the fibrous material to be ground. The free spaces adjacent to or between the grinding sections provide a flow path for the flow of the fibrous material along the blade element 4. The grinding sections and the free spaces of each one or more stator blade elements 4 form a grinding surface 5 of the respective blade element 4. The complete grinding surface of the stator 3 is formed from the grinding surface 5 of a single stator blade element 4 that extends over the entire circumference of the stator 3 or, more generally, from the grinding surfaces 5 of two or more blade elements 4 that have the form of blade segments and are fixed adjacent to each other on the stator 3 such that a complete grinding surface 5 is provided that extends over the entire circumference of the stator 3. In the latter case, the grinding surface 5 of each stator blade segment 4 provides only a part of the complete grinding surface of the stator 3. For clarity, the grinding surface of each one or more stator blade elements 4 and the complete grinding surface of the stator 3 are referred to herein with the same reference number 5. In addition, the same reference number 4 may be used to indicate segment-like blade elements of the stator 3 as well as a single blade element that extends around the entire circumference of the stator 3.

[0013] The grinding device 1 further comprises a rotatable grinding element 6, i.e. the rotor 6 of the grinding device 1. The rotor 6 comprises a hub 7. The rotor 6 further comprises one or more rotor blade elements 8 supported on the hub 7, each rotor blade element 8 comprising a grinding portion and a free space or gap between the grinding portions. The grinding portions and the free space of each of the one or more rotor blade elements 8 form a grinding surface 9 of the respective blade element 8. The complete grinding surface of the rotor 6 is formed from the grinding surface 9 of a single rotor blade element 8 extending over the entire circumference of the stator 6 or, more generally, from the grinding surfaces 9 of two or more blade elements 8 having the form of blade segments and fixed adjacent to each other in the rotor 6 such that a complete grinding surface 9 is provided that extends over the entire circumference of the rotor 6. In the latter case, the grinding surface 9 of each rotor blade segment 8 provides only a part of the complete grinding surface of the rotor 6. For the sake of clarity, both the grinding surface of each one or more rotor blade elements 8 and the complete grinding surface of the rotor 6 are given the same reference sign 9 in this specification. In addition, the same reference numeral 8 may be used to denote segment-like blade elements of the rotor 6 as well as single blade elements extending around the entire circumference of the rotor 6 .

[0014] The hub 7 of the rotor 6 is connected by a shaft 11 to a drive motor 10 so that the rotor 6 can rotate relative to the stator 3, for example in the direction of the arrow RD. The arrow RD therefore indicates the intended direction of rotation RD of the rotor 6.

[0015] The grinding device 1 may also include a loading device, not shown in Fig. 1. The loading device can be used to move the rotor 6 attached to the shaft 11 back and forth, as indicated diagrammatically by the arrow A, to adjust the grinding gap 12 between the stator 3 and the rotor 6, i.e. the size of the grinding chamber 12. The structure and operation of different applicable loading devices are generally known to those skilled in the art and will not be disclosed in more detail herein.

[0016] The fibrous material to be treated is fed to the grinding device 1 through the feed channel 13 as indicated by the arrow F in the form of a fibrous pulp, which is a mixture of water and fibrous material, usually with a viscosity of 3-40%. The fibrous material fed to the grinding device 1 enters the grinding gap 12 through a first end 12' or feed end 12' of the grinding gap 12, which has a smaller diameter. In the grinding gap 12, the fibrous material is treated while the water contained in the material can evaporate. The already treated, i.e. ground, fibrous material leaves the grinding gap 12 through a second end 12'' or discharge end 12'' of the grinding gap 12, which has a larger diameter, and enters the discharge chamber 14. From the discharge chamber 14, the treated material is removed from the grinding device 1 via a discharge channel 15, as indicated diagrammatically by the arrow D.

[0017] It is emphasized that the blade elements of the solution described in this specification are applicable to disc-shaped and cylindrical crushing devices, in addition to conical crushing devices, and to crushing devices comprising both conical and disc-shaped portions.

[0018] According to one embodiment, the grinding device 1 is a refiner for refining fibrous materials, so that the fibrous materials can be virgin fibrous materials or recycled fibrous materials. In refining, a refining effect is exerted on the fibrous material to be treated in order to affect the fibrous properties of the fibrous material. When the grinding device 1 is a refiner, the grinding elements 3, 6, i.e. the stator 3 and the rotor 6, are implemented as refining elements of the refiner and the grinding surfaces 5, 9 of the grinding elements 3, 6 are implemented as refining surfaces of the refining elements and refining surfaces of the blade elements. The refining surfaces of the refining elements / blade elements comprise the blade bars and the blade grooves between the blade bars. In the refining surfaces, the blade bars form a grinding section configured to exert a refining effect on the fibrous material to be treated. The blade bars are typically longitudinal ridges having a straight, curved or substantially continuous shape in their longitudinal direction, the length of each blade bar being usually substantially greater than its width. The blade grooves are the free spaces or gaps remaining between the blade bars to provide channels between the blade bars for the flow of the fibrous material along the refining surface. The longitudinal shape of the blade groove follows the longitudinal configuration or shape of the adjacent blade bars, and thus the length of each blade groove is also typically substantially greater than its width.

[0019] FIG. 2 is a partial cross-sectional view of the stator 3 and the rotor 6 of the grinding device 1 embodied as a conical refiner. In FIG. 2, for the sake of clarity, the rotor 6 has been moved to a non-operating position relative to the stator 3. The stator 3 comprises a number of blade segments 4 fixed adjacent to one another in the circumferential direction of the stator 3, the blade segments 4 comprising blade bars and blade grooves forming the refining surface 5 of each blade segment 4. Similarly, the rotor 6 comprises a number of blade segments 8 fixed adjacent to one another in the circumferential direction of the rotor 6, the blade segments 8 comprising blade bars and blade grooves forming the refining surface 5 of each blade segment 8. For the sake of clarity, the hub of the rotor 6 has been omitted in FIG. 2. The intended direction of rotation RD of the rotor 6 is also indicated diagrammatically in FIG. 2.

[0020] Figure 3 is a highly schematic plan top view of a blade segment 4, 8 applicable to form part of the stator 3 or rotor 6 of the refiner of Figure 2. The blade segment 4, 8 includes an inner or first edge 16 or feed edge 16 oriented towards the first end 12' of the refiner, i.e. towards the end of the stator 3 or rotor 6 having a smaller diameter. The fibrous material to be refined is provided or fed via the first edge 16 to the refining surface 5, 9 of the blade segment 4, 8.

[0021] The blade segments 4, 8 include an outer or first or discharge edge 17 oriented towards the second end 12″ of the refiner, i.e. towards the end of the stator 3 or rotor 6 which has a larger diameter. The refined fiber material is discharged from the refining surfaces 5, 9 via the second edge 17.

[0022] The longitudinal direction or longitudinal axis of the blade segments 4, 8 extends between the inner edge 16 and the outer edge 17 of the blade segments 4, 8. The longitudinal direction or longitudinal axis of the blade segments 4, 8 is indicated, for the sake of clarity, diagrammatically in FIG. 3 by an arrow X on the left side of the blade segments 4, 8. The longitudinal axis X of the blade segments 4, 8 implies the axial direction of the blade segments for blade segments intended for conical or cylindrical crushing devices and the radial direction of the blade segments for blade segments intended for disc-shaped crushing devices. The direction of the blade segments 4, 8 perpendicular to the longitudinal axis X of the blade segments 4, 8 is the circumferential or transverse axis of the blade segments 4, 8. The circumferential or transverse axis is indicated, for the sake of clarity, diagrammatically in FIG. 3 by an arrow C below the blade segments 4, 8.

[0023] The blade segments 4, 8 further include a first or leading side edge 18 extending from an inner edge 16 of the blade segments 4, 8 to an outer edge 17 of the blade segments 4, 8. The first side edge 18 is the edge of the blade segment 4, 8 that first meets an edge of an opposing blade segment in the opposite refining element (stator / rotor) during rotation of the rotor 6. Thus, in the rotor 6, it provides a side edge of the blade segment 8 that is oriented in the intended direction of rotation RD of the rotor 6, and in the stator 3, it provides a side edge of the blade segment 4 that is oriented in the opposite direction relative to the intended direction of rotation RD of the rotor 6.

[0024] The blade segment 4, 8 further comprises a second or trailing edge 19, which is opposite the first side edge 18 in the circumferential direction of the blade segment 4, 8. The second side edge 19 extends from the inner edge 16 of the blade segment 4, 8 to the outer edge 17 of the blade segment 4, 8. The second side edge 19 is thus the edge of the blade segment 4, 8 which lastly meets the edge of the opposing blade segment in the oppositely located refining element (stator / rotor) during the rotation of the rotor 6. Thus, in the rotor 6, a side edge of the blade segment 8 is provided which is directed in the opposite direction to the intended direction of rotation RD of the rotor 6, and in the stator 3, a side edge is provided which is directed in the same direction as the intended direction of rotation RD of the rotor 6. In the embodiment of FIG. 2, the first side edge 18 and the second side edge 19 are straight, but they may also be curved.

[0025] The leading and trailing edges are easily recognizable to one skilled in the art from the bar / groove pattern, particularly the inclination of the bars. The blade bars 20 are always inclined such that they rise from the inner and leading edges to the outer and trailing edges to ensure proper flow of the fibrous material from the feed end to the discharge end.

[0026] The blade segment 4,8 comprises a refining surface 5,9 comprising a blade bar 20 and a blade groove 21, the blade bar 20 and the blade groove 21 having a first dimension in the circumferential direction C of the blade segment 4,8 and a second dimension in the longitudinal or axial or radial direction X of the blade segment 4,8. Thus, the first dimension of the blade bar 20 is the circumferential dimension of the blade bar 20 along the transverse axis C of the blade segment 4,8, and the second dimension of the blade bar 20 is the axial or radial dimension of the blade bar 20 along the longitudinal axis X of the blade segment 4,8. The section of the refining surface 5,9 of the blade segment 4,8 comprising the blade bar 20 and the blade groove 21 forms the refining section 22 of the blade segment 4,8, i.e. the grinding section 22. The section of the refining surface 5,9 of the blade segment 4,8 that is substantially free of the blade bar 20 forms the feed section 23 of the blade segment 4,8. The feed section 23 extends from the inner edge 16 of the blade segments 4, 8 toward the outer edge 17 of the blade segments 4, 8, and may extend to the outer edge 17 as shown diagrammatically in Figure 3. The fiber material to be refined further enters the feed section 23 via the inner edge 16 of the blade segments 4, 8 in response to rotation of the rotor 6, and from the feed section 23 further flows into the refinement section 22. A single blade segment 4, 8 may include one or more refinement sections 22 and one or more feed sections 23.

[0027] In order to prevent excessive wear of the blade bars 20, particularly in the positions next to or close to the feed section 23, and to extend the operating life of the blade segments 4, 8 with satisfactory operating efficiency, an embodiment is shown in FIG. 3 in which, at the same longitudinal position of the blade segments 4, 8, i.e. at the same position of the blade segments 4, 8 in the longitudinal direction, the first dimension of the blade bars 20 in the circumferential direction of the blade segments 4, 8 is larger for the blade bars 20 near the feed section 23 than for the blade bars 20 away from the feed section 23 in the circumferential direction of the blade segments 4, 8.

[0028] 3 shows diagrammatically a dashed reference line L extending in the circumferential direction of the blade segment 4,8 from the inner edge 16 of the blade segment 4,8 at a particular longitudinal position within the blade segment 4,8. The longitudinal position on the reference line L is therefore the same for each blade bar 20 through which the reference line L extends, and each blade bar 20 is designated by the reference numerals 20a, 20b, 20c. From FIG. 3 it can be seen that the first dimension d20a of the blade bar 20a at the reference line L is greater than the corresponding first dimension d20b of the blade bar 20b, such that the blade bar 20a is closer to the feed section 23 than the blade bar 20b in the circumferential direction of the blade segment 4,8 at the particular longitudinal or axial position X of the blade segment 4,8. Similarly, the first dimension d20b of blade bar 20b at the reference line L is greater than the corresponding first dimension d20c of blade bar 20c, such that blade bar 20b is closer to the supply section 23 at a particular longitudinal or axial position X of the blade segments 4, 8 than blade bar 20c in the circumferential direction of the blade segments 4, 8.

[0029] For clarity, the variations in the dimensions of the blade bars 20, 20a, 20b, 20c relative to one another or in the first dimensions of the blade bars 20, 20a, 20b, 20c from one blade bar to another are greatly exaggerated in FIG.

[0030] The embodiment of FIG. 3 is configured such that at the same longitudinal or axial position on the blade segment 4, 8, the first dimension of the blade bar 20 in the circumferential direction of the blade segment 4, 8 is greater towards the feed section 23 in the circumferential direction of the blade segment 4, 8, such that at the same longitudinal or axial position on the blade segment 4, 8, the first dimension of the at least one other blade bar 20 in the circumferential direction of the blade segment 4, 8 is greater than the first dimension of the at least one other blade bar 20 in the circumferential direction of the blade segment 4, 8. The at least one other blade bar 20 is in the circumferential direction of the blade segment 4, 8 and is further away from the feed section 23 than the first-mentioned at least one blade bar 20. The direction of the increase in the first dimension of the blade bar 20 in the circumferential direction C of the blade segment 4, 8 is therefore towards the feed section 13, as indicated diagrammatically by the end of the line L with an arrow pointing towards the feed section 23.

[0031] The first dimension d20a, d20b, d20c of each blade bar 20a, 20b, 20c shown in FIG. 3 is the width of each blade bar 20a, 20b, 20c in the circumferential direction of the blade segments 4, 8. Note that the first dimension d20a, d20b, d20c is not the actual width w20a, w20b, w20c of each blade bar 20a, 20b, 20c because the blade bars 20 are disposed at an angle AG relative to the longitudinal or axial direction X of the blade segments 4, 8. That is, the first dimension d20a, d20b, d20c of each blade bar 20a, 20b, 20c in the circumferential direction C of the blade segments 4, 8 is proportional to the actual width w20a, w20b, w20c of each blade bar 20a, 20b, 20c and the blade bar angle AG relative to the longitudinal direction X of the blade segments 4, 8.

[0032] The effect of the blade bar configuration disclosed in Figure 3 is an increase in the strength of the blade bar against breakage caused by impacts and collisions with foreign objects or contaminants in the pulp mixture, and an increase in the wear resistance of the blade bar 20, especially of the blade bar 20 closest to the feed section 23 in the circumferential direction C of the blade segments 4, 8. This provides a long operating life of the blade segments with satisfactory operating characteristics in terms of the refining effect on the fibrous material to be refined.

[0033] In the embodiment of FIG. 3, the first dimensions d20a, d20b, d20c of the blade bars 20a, 20b, 20c in the circumferential direction of the blade segments 4, 8 are configured to increase substantially continuously toward the feed section 23 in the circumferential direction of the blade segments 4, 8 such that, at the same longitudinal X position on the blade segments 4, 8, the first dimensions d20a, d20b, d20c of the blade bars 20 closer to the feed section 23 in the circumferential direction of the blade segment 20 are greater than the first dimensions d20a, d20b, d20c of adjacent blade bars 20 located further away from the feed section 23.

[0034] According to one embodiment of the blade segment 4, 8, the first dimension of the blade bars in adjacent groups of blade bars 20 at the same longitudinal position on the blade segment 4, 8 is equal, but the first dimension of the blade bars 20 in the circumferential direction of the blade segment 4, 8 is configured to increase stepwise toward the supply section 23 in the circumferential direction of the blade segment 4, 8 such that the first dimension of the blade bars is larger in adjacent groups of blade bars closer to the supply section 23 in the circumferential direction of the blade segment 4, 8.

[0035] According to one embodiment, at the same longitudinal or axial or radial X position of the blade segments 4, 8 in the circumferential direction C of the blade segments 4, 8, the increase in the first dimension of the blade bars 20 between the blade bar 20 located closest to the supply section 23 and the blade bar 20 located furthest from the supply section 23 is between 10 and 80%, preferably between 10 and 50% or between 10 and 30%.

[0036] According to one embodiment, at the same longitudinal or axial or radial X position of the blade segments 4, 8 in the circumferential direction C of the blade segments 4, 8, the width of the blade bar 20 located closest to the feed section 23 is between 1 and 10 mm depending on the type of fiber, typically between 1 and 5 mm for short fiber pulps and between 3 and 7 mm for long fiber pulps. As an example, when refining a short fiber pulp such as a eucalyptus-containing pulp at a low viscosity of 3 to 6%, in a refiner with a steep blade bar angle AG of 10 to 30°, the actual width of the blade bar 20 closest to the inner and leading edges is 1.3 mm, while the actual width of the blade bar 20 closest to the inner and trailing edges of the blade bar 20 is 1.1 mm, an increase in the actual width of about 20%. For long fiber softwood pulp, the respective widths are 6 mm closest to the feed section and 4 mm closest to the opposite edges, an increase in width of about 50%.

[0037] Figure 4 discloses the same blade segments 4, 8 as in Figure 3. As such, Figure 3 is a largely schematic planar top view of the blade segments 4, 8 applicable to form part of the stator 3 or rotor 6 in the refiner of Figure 2. The blade segments 4, 8 of Figure 3 are shown again in Figure 4 to improve clarity of some possible additional embodiments of the blade segments 4, 8 disclosed above and the presentation of reference numbers that relate inter alia to these additional embodiments of the blade segments 4, 8.

[0038] In FIG. 4, at a particular circumferential position C, i.e. from the feed section 23 of each of the blade segments 4, 8 along the transverse axis C of the grinding section 22 of the blade segment 4, 8, there is a dashed reference line L' extending in the longitudinal or axial direction X of the blade segment 4, 8. The circumferential position C of the reference line L' is therefore the same for each blade bar 20 along which the reference line L' extends, and the respective blade bars 20 are again indicated here with the reference signs 20a, 20b, 20c. From FIG. 4, it can be seen that the second dimension e20a of the blade bar 20a at the reference line L' in the longitudinal or axial direction X of the blade segment 4, 8 is greater than the corresponding second dimension e20b of the blade bar 20b. The blade bar 20a is closer to the outer edge 17 than the blade bar 20b at a particular circumferential position C of the blade segment 4, 8 in the longitudinal or axial direction X of the blade segment 4, 8. Similarly, a second dimension e20b of blade bar 20b at a reference line L' in the longitudinal or axial direction X of the blade segments 4, 8 is greater than a corresponding second dimension e20c of blade bar 20c. Blade bar 20b is closer to the outer edge 17 in the longitudinal direction X of the blade segments 4, 8 than blade bar 20c at a particular circumferential position C of the blade segments 4, 8.

[0039] Again, for clarity, the variations in the mutual dimensions of the blade bars 20, 20a, 20b, 20c or the second dimensions of the blade bars 20, 20a, 20b, 20c from one blade bar to another have been greatly exaggerated in FIG.

[0040] Thus, the embodiment of figure 4 discloses a blade segment 4,8 configured such that at the same circumferential position on the blade segment 4,8, the second dimension of the blade bar 20 in the longitudinal direction X of the blade segment 4,8 increases towards the outer edge 17 of the blade segment 4,8 in the longitudinal direction of the blade segment 4,8, such that at the same circumferential position on the blade segment 4,8, the second dimension of the at least one blade bar 20 is greater than the second dimension of at least one other blade bar 20. The at least one other blade bar 20 is further away from the outer edge 17 of the blade segment 4,8 in the longitudinal direction of the blade segment 4,8, i.e. closer to the inner edge 16 of the blade segment 4,8 than the first-mentioned at least one blade bar 20. Thus, the direction of increase of the second dimension of the blade bar 20 in the longitudinal direction X of the blade segments 4, 8 occurs towards the outer edge 17 of the blade segments 4, 8, i.e., in the longitudinal direction X of the blade segments, as indicated diagrammatically by the end of the line L' including an arrow pointing towards the outer edge of the blade segments 4, 8.

[0041] The second dimension e20a, e20b, e20c of each blade bar 20a, 20b, 20c shown in FIG. 4 is the width of each blade bar 20a, 20b, 20c in the longitudinal direction X of the blade segments 4, 8. Note that the second dimension e20a, e20b, e20c is not the actual width w20a, w20b, w20c of each blade bar 20a, 20b, 20c, because the blade bars 20 are disposed at an angle AG with respect to the longitudinal direction X of the blade segments 4, 8. That is, the second dimension e20a, e20b, e20c of each blade bar 20a, 20b, 20c in the longitudinal direction X of the blade segments 4, 8 is proportional to the actual width w20a, w20b, w20c of each blade bar 20a, 20b, 20c and the blade bar angle AG with respect to the longitudinal direction X of the blade segments 4, 8. The importance of the blade bar angle AG for the second dimension is significantly greater than for the first dimension since the blade bar angle is usually significantly less than 45°.

[0042] The effect of the blade bar configuration disclosed in FIG. 4 is to increase the wear resistance of the blade bar 20, especially in the longitudinal direction X of the blade segments 4, 8, close to the outer edge 17 of the blade segments. This high wear rate is subject to a higher wear rate of the blade bar substantially close to the outer edge 17 of the blade segments 4, 8. This high wear rate is due to the higher circumferential speed at the outer periphery of the blade segment, since the shear forces that affect the wear rate of the blade bar depend on the circumferential speed. With the embodiment of FIG. 4, the blade bar 20 at the outer edge is well saved from rubbing off, so that the refining gap remains constant up to the outer edge. The embodiment of FIG. 4 provides a longer operating life of the blade segments with satisfactory operating characteristics in terms of the refining effect on the fiber material to be refined.

[0043] In the embodiment of FIG. 4, the second dimensions e20a, e20b, e20c of the bars 20a, 20b, 20c in the longitudinal or axial direction X of the blade segments 4, 8 are configured to increase substantially continuously towards the outer edge 17 of the blade segments 4, 8 in the longitudinal direction X of the blade segments 4, 8, such that at the same circumferential C position on the blade segments 4, 8, the second dimensions e20a, e20b, e20c of the blade bars 20 near the outer edge 17 in the longitudinal direction X of the blade segments 4, 8 are greater than the second dimensions e20a, e20b, e20c located away from the outer edge 17.

[0044] According to one embodiment of the blade segment 4, 8, the second dimension of the blade bars 20 in a group of adjacent blade bars 20 at the same circumferential C position on the blade segment 4, 8 is equal, but the second dimension of the blade bars 20 in the longitudinal or axial direction X of the blade segment 4, 8 is configured to increase stepwise toward the outer edge 17, such that the second dimension of the blade bars 20 in a group of adjacent blade bars 20 closer to the outer edge 17 in the longitudinal direction X of the blade segment 4, 8 is increased. Here, the term group of adjacent blade bars 20 refers to two or more blade bars 20 adjacent in the longitudinal direction X of the blade segment 4, 8.

[0045] According to one embodiment, at the same circumferential C position of the blade segments 4, 8 in the longitudinal or axial direction X of the blade segments 4, 8, the increase in the second dimension of the blade bars 20 between the blade bar 20 located closest to the inner edge 16 and the blade bar 20 located furthest from the inner edge 16 is between 10 and 100%, preferably between 10 and 50%.

[0046] In the embodiment of Figures 3 and 4, each blade bar 20 has a constant width along its length, however, the design principles disclosed above may also be applied to blade bars configured to increase or decrease in width along their length.

[0047] According to one embodiment, the grinding device 1 is a disperser for dispersing fibrous material, so that the fibrous material can be recycled fibrous material. In dispersion, a dispersing effect is exerted on the fibrous material to be treated in order to break down contaminants in the fibrous material to reduce their adverse effects in the further use of the dispersed fibrous material or to facilitate the removal of the contaminants. When the grinding device 1 is a disperser, the grinding elements 3, 6, i.e. the stator 3 and the rotor 6, are implemented as dispersing elements of the disperser, and the grinding surfaces 5, 9 of the grinding elements 3, 6 are implemented as dispersing surfaces of the dispersing elements. The dispersing surfaces of the dispersing elements include protrusions and gaps between the protrusions. The protrusions form dispersing parts in the dispersing surfaces that are configured to exert a dispersing effect on the fibrous material to be treated. The protrusions typically have a structure that is substantially small in length and width, and the length of the protrusions is typically not substantially greater than the width of the protrusions. However, the shape of the protrusions can vary in various ways, including, for example, various kinds of polygons or pyramids, etc. The gap is the free space or gap left between the protrusions to provide a flow path for the flow of the fibrous material to be treated along the dispersing surface. At the dispersing surface of the disperser, the distance between adjacent protrusions is typically much greater than the distance between adjacent blade grooves, i.e., the width of the blade grooves at the refining surface of the refiner.

[0048] Figure 5 is a highly schematic planar top view of blade segments 4, 8 applicable for forming part of the stator 3 or rotor 6 in a disc-shaped disperser. The basic structure of the blade segments 4, 8 in Figure 5 is similar to that in Figure 3, the main difference being that the blade segments 4, 8 in Figure 5 are intended as disc-shaped grinding elements, whereas the blade segments 4, 8 in Figure 3 are intended as cone-shaped grinding elements.

[0049] The blade segments 4,8 include dispersive surfaces 5,9 which include protrusions 24,25,26 or teeth 24,25,26 and gaps 27 between the protrusions 24,25,26. The protrusions 24,25,26 are arranged in circumferentially extending rows located from the inner edge 16 of the blade segments 4,8 at different positions in the longitudinal direction X of the blade segments 4,8, each row having a suitable number of respective protrusions 24,25,26. The protrusions 24,25,26 and gaps 27 have a first dimension in the circumferential direction C of the blade segments 4,8 and a second dimension in the longitudinal direction X of the blade segments 4,8. The first dimension of the projections 24, 25, 26 is therefore the circumferential dimension of the projections 24, 25, 26, and the second dimension of the projections 24, 25, 26 is therefore the dimension of the projections 24, 25, 26 along the longitudinal axis X of the blade segment. The section of the dispersion surface 5, 9 of the blade segment 4, 8 comprising the projections 24, 25, 26 and the gap 27 forms the dispersion section 22, i.e. the grinding section 22 of the blade segment 4, 8. The section of the dispersion surface 5, 9 of the blade segment 4, 8 which is substantially free of the projections 24, 25, 26 forms the feed section 23 of the blade segment 4, 8. The feed section 23 extends from the inner edge 16 of the blade segment 4, 8 towards the outer edge 17 of the blade segment 4, 8 and may extend up to the outer edge 17 as shown diagrammatically in FIG. 5. The fibrous material to be processed enters the feed section 23 via the inner edges 16 of the blade segments 4, 8 in response to rotation of the rotor 6, and from the feed section 23 further flows into the dispersion section 22. A single blade segment 4, 8 may include one or more dispersion sections 22 and one or more feed sections 23.

[0050] In order to prevent excessive wear of the protrusions 24, 25, 26, especially in the position next to or close to the feed section 23, and to extend the operating life of the blade segments 4, 8 with satisfactory operating efficiency, an embodiment is shown in Fig. 5, in which, at the same longitudinal or radial X position of the blade segment 4, 8, the first dimension d24a, d24b, d24c of the protrusions 24 is configured to be larger for the protrusions 24 closer to the feed section 23 than for the protrusions 24 further away from the feed section 23 in the circumferential direction C of the blade segment 4, 8. The same characteristic applies for the dimensions of the protrusions 25, 26, so that the first tooth 24a, 25a, 26a closest to the leading edge 18 is wider than the next tooth 24b, 25b, 26b towards the trailing edge 19.

[0051] In order to prevent excessive wear of the protrusions 24, 25, 26, particularly at a position next to or close to the outer edge 17 of the blade segment 4, 8, and thus to extend the operational life of the blade segment 4, 8, an embodiment is shown in Fig. 5, in which, at the same circumferential position C of the blade segment 4, 8, the second dimensions e24a, e25a, e26a of the protrusions 24, 25, 26 are configured in the longitudinal direction X of the blade segment 4, 8 to be larger for the protrusion 26 closer to the outer edge 17 than for the protrusion 25, and similarly, larger for the protrusion 25 closer to the outer edge 17 than for the protrusion 24 further away from the outer edge 17.

[0052] The above description of the dimensions of the blade bar 20 in relation to the embodiment of figures 3 and 4 is applicable to the dimensions of the protrusions 24, 25, 26 in the embodiment of figure 5 by replacing the term "blade bar" with the term "protrusion" (including the possible angle between the longitudinal direction X of the blade segments 4, 8 and the application orientation of the protrusions 24, 25, 26 in the distribution planes 5, 9), as will be obvious to the skilled person. Due to the application orientation of the protrusions 24, 25, 26 relative to the longitudinal or radial direction X of the blade segments 4, 8, the first dimension of the protrusions 24, 25, 26 in the circumferential direction C of the blade segments 4, 8 and the second dimension of the protrusions 24, 25, 26 in the longitudinal or radial direction X of the blade segments 4, 8 may differ from the actual dimensions of the protrusions 24, 25, 26, which are considered to give the width or length of the protrusions 24, 25, 26.

[0053] It is obvious to those skilled in the art that with the advancement of technology, the concept of the present invention can be implemented in various ways. The present invention and its embodiments are not limited to the embodiments described above, but may vary within the scope of the claims.

Claims

1. A blade element for a comminuting device for comminuting fibrous material, the blade element comprising: an inner edge and an outer edge; At least one grinding section including a plurality of grinding sections and a free space between the plurality of grinding sections that serves as a flow path for the flow of fibrous material, each of the grinding sections having a first dimension and a second dimension, the first dimension being a width of the grinding section extending in a circumferential direction of the blade element and the second dimension being a width of the grinding section extending in a longitudinal direction of the blade element; Including, The blade element comprises: at least one feed section extending at least partially along the longitudinal direction of the blade element from the inner edge to the outer edge, each of said feed sections communicating with said free space and intended to feed fibrous material to each of said comminution sections via said free space; Further comprising: At the same longitudinal position of the blade element, a first dimension of the grinding portion is configured to increase in a circumferential direction of the blade element towards the feed section; A blade element configured such that at the same circumferential position of the blade element, the second dimension of at least one grinding portion increases in the longitudinal direction of the blade element toward the outer edge such that the second dimension of the grinding portion is greater in the longitudinal direction of the blade element than a corresponding second dimension of at least one other grinding portion away from the outer edge.

2. 2. The blade element of claim 1, wherein the plurality of grinding sections are configured such that their first dimension increases gradually toward the feed section in a circumferential direction of the blade element such that the grinding sections near the feed section have a first dimension greater than the grinding sections located away from the feed section.

3. The blade element of claim 1 , wherein the first dimension of the comminution portion is proportional to an actual width of the comminution portion.

4. 2. The blade element of claim 1, wherein at the same longitudinal position of the blade element, an increase in a first dimension of the grinding section between the grinding section located closest to the feed section and the grinding section located farthest from the feed section is 10 to 80%.

5. 2. The blade element of claim 1, wherein at the same longitudinal position of the blade element, an increase in a first dimension of the grinding section between the grinding section located closest to the feed section and the grinding section located farthest from the feed section is 10 to 50%.

6. 2. The blade element of claim 1, wherein the plurality of grinding portions are configured such that their second dimension increases gradually toward the outer edge of the blade element such that the grinding portions near the outer edge have a second dimension greater than the grinding portions located away from the outer edge in the longitudinal direction of the blade element.

7. 2. The blade element of claim 1, wherein an increase in a second dimension of the comminution between the comminution located closest to the inner edge and the comminution located farthest from the inner edge is between 10% and 100%.

8. 2. The blade element of claim 1, wherein an increase in the second dimension of the comminution between the comminution located closest to the inner edge and the comminution located farthest from the inner edge is 10-50%.

9. A comminuting device for comminuting fibrous material, the comminuting device comprising at least one blade element according to any one of claims 1 to 8.

10. 10. The comminution device according to claim 9, wherein the comminution device is a refiner for refining fibrous material.

11. The grinding device according to claim 10, wherein the grinding device is a disperser for dispersing fibrous material.

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