Blade segments for refiners

Abstract

A blade segment (4, 4a, 4b, 8, 8a, 8b) for a refiner (1) for refining fibrous material includes a first edge (20) and a second edge (21) and a first side edge (22) and a second side edge (23) extending between the first edge (20) and the second edge (21). The segment includes a refining surface (5, 9) including a blade bar (27) and a blade groove (28) on a forward surface (25) of the segment, and at least one opening (14, 15) in the side edge (22, 23), the opening extending through the entire thickness of the blade segment body toward the opposite side edge (22, 23). On the background surface side of the segment, there is a height difference between the background surface (26) at the first side edge and the background surface (26) at the second side edge at least at the opening of the segment.

Description

[Technical Field]

[0001] The present invention relates to a refiner for refining fibrous material, and more particularly to a blade segment for a refiner for refining fibrous material. [Background technology]

[0002] Refiners used to refine fibrous materials, such as those used to produce mechanical pulp or in any low-consistency refining process, typically include two refining elements that face each other and rotate relative to each other, i.e., one or both of them are rotating. The refining elements include a refining surface with a blade bar and a blade groove between them, where the blade bar is intended to defiber and refine the material to be refined, and the blade groove is intended to carry the material to be refined forward along the refining surface. The refining surface of a refining element is typically formed by several blade segments fastened to the body of each refining element. Thus, the complete refining surface of a refining element is formed by the refining surfaces of several blade segments fastened adjacent to each other within the refiner.

[0003] Patent Document 1 discloses a blade segment including a refining surface on its forward surface, the refining surface including blade bars and blade grooves therebetween. The blade segment of Patent Document 1 includes an opening on at least one side edge of the blade segment, extending through the entire thickness of the blade segment toward the opposite side edge. The opening may be adapted to feed fibrous material to be refined into a refining chamber between opposing refining elements of a refiner, as well as to discharge fibrous material already refined in the refining chamber out of the refiner chamber. Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel blade segment for a refiner for refining fibrous material, as well as a novel refiner for refining fibrous material. [Means for solving the problem]

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

[0006] The invention is based on the idea of ​​providing, on the side of the background surface of the blade segment, a height difference between the background surface at a first side edge and the background surface at a second side edge at least at the opening of the blade segment.

[0007] The height difference on the side of the background surface of the blade segment forms or provides a guide element or guide surface that enhances the delivery of the material to be refined through the openings in the refining surface of the blade segment and into the refining chamber of the refiner.

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

[0009] In the following, the present invention will be described in more detail by means of preferred embodiments with reference to the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic general cross-sectional side view of a conical refiner.

[0011] [Figure 2] FIG. 2 is a schematic plan top view of a blade segment.

[0012] [Figure 3] 3 is a schematic plan top view of a set of two adjacent blade segments having the blade segment implementation of FIG. 2.

[0013] [Figure 4]FIG. 10 is a schematic top perspective view of a portion of another set of adjacent blade segments as applied in a rotor of a conical refiner.

[0014] [Figure 5] 2, 3 and 4 taken along section line AA shown in FIGS. 3 and 4. FIG.

[0015] [Figure 6] 2, 3 and 4 taken along section line AA shown in FIGS. 3 and 4. FIG.

[0016] [Figure 7] 2, 3 and 4 taken along section line AA shown in FIGS. 3 and 4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] For clarity, the figures illustrate some embodiments of the invention in a simplified manner, and like reference numbers identify like elements in the figures.

[0018] FIG. 1 is a schematic, general cross-sectional side view of the general structure of a refiner 1, which may be used to refine fibrous materials, such as lignocellulose-containing wood materials or other fibrous materials suitable for use in producing paper or paperboard. The refiner 1 shown in FIG. 1 is of a conical type, but for purposes of illustration, disc refiners, conical disc refiners, and cylindrical refiners may be used as well. Generally, refiners include at least two substantially oppositely positioned refining elements, at least one of which is rotating, and a refining chamber formed between each pair of substantially oppositely positioned refining elements. Refining elements with only one rotatable refining element are described below.

[0019] The refiner 1 of FIG. 1 includes a frame 2 and a stationary, fixed refining element 3, i.e., a stator 3, supported by the frame 2. The stator 3 includes more than two stator blade segments 4, each of which includes a blade bar and a blade groove therebetween. The blade bar and blade groove in each stator blade segment 4 form a refining surface 5 of the respective blade segment 4, which thereby provides a portion of the refining surface of the stator 3. The complete refining surface of the stator 3 is formed by the refining surfaces 5 of the required number of blade segments 4 fastened adjacent to one another within the stator 3 to provide a complete refining surface 5 extending around the entire circumference of the stator 3. For clarity, both the refining surface of each single stator blade segment 4 and the complete refining surface of the stator 3 are designated herein by the same reference numeral 5.

[0020] The refiner 1 further includes a rotatable refining element 6, i.e., a rotor 6, of the refiner 1. The rotor 6 includes a hub 7. The rotor 6 further includes more than two rotor blade segments 8 supported on the hub 7, each rotor blade segment 8 including a blade bar and a blade groove therebetween. The blade bars and blade grooves in each rotor blade segment 8 form a refining surface 9 of the respective rotor blade segment 8, which thereby provides a portion of the refining surface of the rotor 6. The complete refining surface 9 of the rotor 6 is formed by the refining surfaces 9 of a required number of blade segments 8 fastened adjacent to one another within the rotor 6 to provide a complete refining surface 9 extending around the entire circumference of the rotor 6. For clarity and simplicity, both the refining surface of each single rotor blade segment 8 and the complete refining surface of the rotor 6 will be designated herein by the same reference numeral 9.

[0021] The hub 7 of the rotor 6 is connected to a drive motor 10 by a shaft 11 so that the rotor 6 can be rotated relative to the stator 3, for example in the direction of the arrow RD, which thus indicates the intended direction of rotation RD of the rotor 6.

[0022] Refiner 1 may also include a loading device, which for clarity is not shown in Figure 1. The loading device can be used to move rotor 6, which is attached to shaft 11, back and forth as shown diagrammatically by arrow A to adjust the size of the refining gap 12 between stator 3 and rotor 6, i.e., the refining chamber 12, in which the fibrous material is actually refined.

[0023] Fibre material to be refined is fed into refiner 1 via feed channel 13 in the manner indicated by arrow F. In one embodiment, a majority of the fibrous material fed into refiner 1 passes through openings 14 formed in rotor blade segments 8 in the manner indicated generally by arrow P into refining chamber 12 where the fibrous material will be refined. Furthermore, a majority of the already refined fibrous material then passes through openings 15 formed in stator blade segments 4 into intermediate space 16 between frame 2 and stator 3 of refiner 1, from where the refined material is removed via discharge channel 17 from refiner 1 as indicated generally by arrow D.

[0024] Since the space between the rotor 6 and the frame 2 of the refiner 1 of Figure 1 is not completely closed, a portion of the fibrous material to be fed to the refiner 1 is transferred into the refining chamber 12 from the right end of the refining chamber 12, i.e., from the first end 18 or inner end 18 of the refiner 1, which has a smaller diameter, as can be seen in Figure 1. Correspondingly, a portion of the material that has already been refined leaves the refining chamber 12 from the left end of the refining chamber 12, i.e., from the second end 19 or outer end 19 of the refiner 1, which has a larger diameter, as can be seen in Figure 1, from which a connection is provided to the intermediate space 16.

[0025] In the embodiment of refiner 1 shown in FIG. 1 , only one feed channel 13 is provided, located at the first end 18 of refiner 1, which has a smaller diameter. An actual implementation of the refiner may also include a second feed channel located at the second end 19 of refiner 1, which has a larger diameter, such that the discharge channel 17 of refiner 1 may be located, for example, somewhere between the first and second ends 18 and 19 of refiner 1. Hereinafter, the terms "reference symbol 18" and "first end 18" or "inner end 18" may refer to both the first end 18 or inner end 18 of refiner 1, which has a smaller diameter, and the first end 18 or inner end 18 of refining elements 3, 6 or refining chamber 12, which have a smaller diameter. Correspondingly, the terms "reference symbol 19" and "second end 19" or "outer end 19" may refer to the second end 19 or outer end 19 of refiner 1, which has a larger diameter, and the second end 19 or outer end of refining elements 3, 6 or refining chamber 12, which have a larger diameter.

[0026] It is emphasized that in addition to the conical refiners disclosed above, the blade segments of the solutions described herein may also be applied to other types of conical refiners. In addition to conical refiners, the blade segments of the solutions described herein are applicable to disc refiners and cylindrical refiners, and to refiners that include both conical and disc sections.

[0027] Figure 2 is a schematic plan top view of blade segments 4, 8 applicable to be used to form a portion of the refining surface 5, 9 of a stator 3 or rotor 6, whereby the complete refining surface 5, 9 is provided by adjacently arranging the required number of blade segments 4, 8 of Figure 2 around the circumference of the stator 3 or rotor 6. Figure 3 is a schematic plan top view of a set of two adjacent blade segments 4a, 4b, 8a, 8b having mountings corresponding to the blade segments 4, 8 of Figure 2, and Figure 3 illustrates how the blade segments 4, 8 are attached to their respective stators 3 or rotors 6.

[0028] The blade segments 4, 8 include inner or first end edges 20 that are oriented toward the inner ends 18 of the refining elements 3, 6, which have smaller diameters. The blade segments 4, 8 further include outer or second end edges 21 that are oriented toward the outer ends 19 of the refining elements 3, 6, which have larger diameters. The blade segments 4, 8 have longitudinal axes extending from the inner or first end edges 20 to 21 and width directions transverse to the longitudinal axes, the longitudinal axes of the blade segments being indicated diagrammatically by arrows LA. When installed in a refiner, the longitudinal axes LA provide the refiner's axial direction in the case of conical and cylindrical refiners and the refiner's radial direction in the case of disc refiners.

[0029] The blade segments 4, 8 further include a first or leading side edge 22 that extends from the inner edge 20 of the blade segment 4, 8 to the outer edge 21 of the blade segment 4, 8 and provides the side edge of the blade segment 4, 8 that first contacts the edge of the counter blade segment during rotation of the rotor 6, and thus provides the side edge of the blade segment to be oriented in the intended direction of rotation RD of the rotor 6. The blade segments 4, 8 further include a second or trailing side edge 23 opposite the first side edge 22 across the width of the blade segment 4, 8. The second side edge 23 extends from the inner edge 20 of the blade segment 4, 8 to the outer edge 21 of the blade segment 4, 8 and provides the side edge of the blade segment 4, 8 that last contacts the edge of the counter blade segment during rotation of the rotor 6, and thus provides the side edge of the blade segment that should be oriented in a direction opposite to the intended direction of rotation RD of the rotor 6. The inner edge 20 and the outer edge 21, together with the first side edge 22 and the second side edge 23, define the periphery of the blade segment 4, 8.

[0030] The blade segments 4, 8 have a body 24 with a forward surface 25 to be oriented toward the refining chamber 12 of the refiner 1 and a background or rear surface 26 to be oriented toward the hub 7 of the rotor 6, as shown, for example, in FIG. 5 . The forward surface 25 of the blade segment body 24 is provided with a blade bar 27 and a blade groove 28, which together provide the refining surfaces 5, 9 of the blade segments 4, 8. The blade bar 27 is intended to defiber and refine the material to be refined, and the blade groove 28 is intended to carry the material to be refined forward along the refining surfaces 5, 9.

[0031] The blade segment of the solution disclosed herein comprises an opening 14, 15 in at least one of its side edges 22, 23. The opening 14, 15 may have the form of an indent as shown schematically in Figures 2 and 3 or a continuous slit or bay as shown schematically later in Figure 4.

[0032] The blade segments 4, 8 of FIG. 2 have openings 14, 15 at a first side edge 22 of the blade segments 4, 8. The openings 14, 15 extend from the first side edge 22 toward the opposite second side edge 23 such that the openings 14, 15 have both a dimension in the direction of the longitudinal axis LA and a dimension in the width direction of the blade segments 3, 8. In other words, there is at least one opening 14, i.e., more than one opening 14, at the first side edge 22 of the blade segments 4, 8 such that the first side edge 22 does not form a perfectly straight line between the inner edge 20 and the outer edge 21. The openings 14, 15 extend from a forward surface 25 of the blade segment body 24 to a rear or background surface 26 of the blade segment body 24, such that the openings 14 extend through the entire thickness of the blade segments 4, 8 or the blade segment body 24.

[0033] 2 shows an embodiment of blade segments 4, 8 having four openings 14 at first side edge 22 of blade segments 4, 8. Alternatively, blade segment 4, 8 may include one or more openings 14 at second side edge 23 extending from second side edge 23 toward opposite first side edge 22 such that second side edge 23 does not form a perfectly straight line between inner edge 20 and outer edge 21.

[0034] 4 schematically illustrates a top perspective view of a portion of another set of adjacent blade segments 8a, 8b as applied to rotor 6 of conical refiner 1. Blade segments 8a, 8b in FIG. 4 include shoulder members 32, 33, 34, 35 proximate the corners of blade segments 8a, 8b: shoulder member 32 at first edge 20 of blade segment 8a, 8b on the side of first side edge 22; shoulder member 33 at first edge 20 of blade segment 8a, 8b on the side of second side edge 23; shoulder member 34 at second edge 21 of blade segment 8a, 8b on the side of first side edge 22; and shoulder member 35 at second edge 21 of blade segment 8a, 8b on the side of second side edge 23. Shoulder members 32, 33, 34, 35 are intended to contact corresponding shoulder members on adjacent blade segments when assembled to provide a portion of the refining surface of the refining element of the refiner. Figure 4 shows schematically fastening holes 36 intended to receive fastening means, such as bolts, for fastening the blade segments to the hub 7 of the rotor 6 or to any support structure, either directly or via a support means, such as a fastening ring 37.

[0035] Between the shoulder members 32, 34 at the first side edge 22 of the blade segments 8 a, 8 b, the first side edge 22 includes multiple longer edge portions 22 a connected by elbows 22 b therebetween, i.e., there is an elbow 22 b between two consecutive longer edge portions 22 a. The longer edge portions 22 a and elbows 22 b are positioned away from the longitudinal axis LA of the blade segments 8 a, 8 b so that a substantially continuous slit- or bay-shaped opening 14 is disposed at the first side edge 22 of the blade segments 8 a, 8 b.

[0036] In the embodiment of FIG. 4, the longer edge portions 22a are arranged to deviate in the same direction relative to the direction of the longitudinal axis LA, and the elbows 22b are rotated away from the longer edge portions 22a to deviate in a different direction relative to the direction of the longitudinal axis LA, although other mutual implementations of the longer edge portions 22a and the elbows 22b are possible.

[0037] Similar longer edge portions and elbows as discussed above may be applied to the second side edges 23 of the blade segments 23, whereby the slit- or bay-like openings 14 in the first and / or second side edges 22, 23 of the blade segments 8a, 8b provide substantially continuous slit- or bay-like openings 14 having a sort of zigzag configuration between adjacent blade segments 8a, 8b in the rotor 6.

[0038] Similar structures and related descriptions of the blade segments as disclosed in FIG. 4 may apply correspondingly to the stator 3 of the refiner 1 .

[0039] The embodiments of the blade segments 4, 4a, 4b, 8, 8a, 8b of Figures 2 and 3 and the blade segments 8a, 8b of Figure 4 further include a feed groove 29. A more detailed discussion of the feed groove 29 is disclosed later in this description.

[0040] Referring to Figures 3 and 4, which show schematic planar top views of a set of two adjacent blade segments 4a, 4b, 8a, 8b, i.e., a first blade segment 4a, 8a and a second blade segment 4b, 8b, it can be seen that openings 14, 15 in the first blade segment 4a, 8a remain between a first side edge 22 of the first blade segment 4a, 8a and a second side edge 23 of the adjacent second blade segment 4b, 8b. In other words, the walls 14a, 14b, 15a, 15b of the openings 14, 15 are formed by the side edges 22, 23 of two adjacent blade segments 4a, 4b, 8a, 8b such that the first side edge 22 of the first blade segment 4a, 8a forms or provides the first wall 14a, 15a of the opening 14, 15 at each opening 14, 15, and the second side edge 23 of the second blade segment 4b, 8b forms or provides the second wall 14b, 15b of the opening 14, 15 at each opening 14, 15. In Figure 3, the openings 14, 15 have the form of a recess, and in Figure 4, the opening 14 has the form of a continuous slit or bay.

[0041] Figure 5 is a schematic, partially cross-sectional end view of a first embodiment of the blade segments 8, 8a, 8b of Figures 2, 3 and 4 taken along section line A-A shown in Figures 3 and 4. The feed grooves 29 have been omitted in Figure 5. Furthermore, it should be noted that even in Figure 5, and later in Figures 6 and 7, the structure of the blade segments is disclosed with respect to rotor blade segments, and similar structures of the blade segments are also applicable to stator blade segments.

[0042] In the embodiment of Figure 5, at least at each opening 14 of the blade segments 8, 8a, 8b, a protrusion 30 is disposed on the background or rear surface 26 of the first side edge 22 of the blade segment 8, 8a, 8b. In other words, the blade segments 8, 8a, 8b include a protrusion 30 on the background surface 26 of the blade segment body 24, at least on the first wall 14a of each opening 14. The protrusion extends substantially beyond the rear plane of the blade segment, i.e., within the rotor 6, substantially toward the center of the rotor 6, when the blade segment 8, 8a, 8b is to be mounted on the rotor 6. Although the protrusion 30 may extend the entire longitudinal length of the blade segment 8, 8a, 8b, the protrusion 30 extends at least substantially the longitudinal extent of the opening 14, preferably at least at each opening 14 of the blade segments 8, 8a, 8b.

[0043] 5, the protrusion 30 is a solid portion of the body 24 of the blade segment 8, 8a, 8b. Alternatively, the protrusion 30 can be a separate part that is welded, soldered, or in some other way fastened to the body 24 of the blade segment 8, 8a, 8b.

[0044] The disclosed protrusions 30 provide a height difference between the background surface 26 at the first side edge 22 of the blade segments 8, 8a, 8b and the background surface 26 at the second side edge 23 of the blade segments 8, 8a, 8b at the opening 14 of the blade segment 8, preferably at each opening 14, on the side of the background or rear surface 26 of the blade segments 8, 8a, 8b. In other words, the disclosed protrusions 30 provide a height difference between the background surface 26 at the first wall 14a of the opening 14 of the blade segment 8 and the background surface 26 at the second wall 14b of the opening 14, preferably at at least each opening 14, at the opening 14 on the side of the background surface 26 of the blade segments 8, 8a, 8b.

[0045] The height difference between the background surface 26 at the first side edge 22 of the blade segment 8, 8a, 8b and the background surface 26 at the second side edge 23 of the blade segment 8, 8a, 8b is considered with respect to the reference level provided by the level or plane of the background surface 26, and does not take into account possible protrusions in the body 24 of the blade segment 8, 8a, 8b intended, for example, to support the blade segment 8, 8a, 8b on the hub 7 of the rotor 6, or cavities or pockets in the body 24 of the blade segment 8, 8a, 8b intended to lighten the structure of the body 24 of the blade segment 8, 8a, 8b.

[0046] The height difference caused by the protrusions 30 forms wing-like structures or guide elements or guide surfaces on the side of the background surfaces 26 of the blade segments 8, 8a, 8b, which, during operation of the refiner, guide the flow of material toward the openings 14, thereby enhancing the flow of material to be refined from the side of the background surfaces 26 of the blade segments through the openings 14 to the side of the forward surfaces 25 of the blade segments, i.e., to the refining surfaces 9 of the blade segments 8, 8a, 8b, or into the refining chamber 12 between the stator 3 and the rotor 6. The feeding direction of the material to be refined in the rotor 6 is indicated diagrammatically by arrow FI.

[0047] The improved flow of material to be refined into the refining chamber 12 has the effect that the material to be refined does not block the openings 14, which in turn has the effect of more consistent overall refining results. Furthermore, the operating pressure of the refiner is better maintained, such that there is a higher post-refiner pressure than before, which provides a higher capacity in the refiner. The higher capacity to be achieved also means that the same capacity as before can be obtained even if the opening area of ​​the openings 14 is reduced. This in turn makes it possible to increase the cutting edge length of the blade bars 27 of the blade segments 8, 8a, 8b, particularly for improved refining of hardwood.

[0048] According to one embodiment, at least one side edge of the blade segment is inclined, over at least a portion of its thickness, towards or away from the adjacent wall 14a, 14b of the blade segment's opening 14. According to this embodiment, the first side edge 22 of the blade segment 8, 8a, 8b, i.e., the first wall 14a of the opening 14, and / or the second side edge 23 of the blade segment 8, 8a, 8b, i.e., the second wall 14b of the opening 14, is inclined, over at least a portion of its thickness, at the opening 14 of the blade segment 8, 8a, 8b.

[0049] 4, both the first side edge 22 of the blade segments 8, 8a, 8b and the second side edge 23 of the blade segments 8, 8a, 8b are sloped in their thickness direction such that the rear surface corner of the first side edge 22 extends further toward the intended direction of rotation RD of the rotor 6, i.e., extends further from the second side edge 23 of the blade segments 8, 8a, 8b than the leading surface corner, and such that the rear surface of the second side edge 23 extends further toward the intended direction of rotation RD of the rotor 6, i.e., extends further toward the first side edge 22 of the blade segments 8, 8a, 8b than the leading surface corner of the second side edge 23. This slope of the walls 14a, 14b of the opening 14 has the effect of improving the feeding of the material to be refined through the opening 14 into the refining chamber 12 between the stator 3 and the rotor 6 when the refiner 1 is in use.

[0050] According to one embodiment, the side edges of the blade segments are inclined at a substantially different angle from one another at least in each opening of the blade segments, at least over at least a portion of their thickness direction. According to this embodiment, the first side edge 22 of the blade segments 8, 8a, 8b, i.e., the first wall 14a of the opening 14, and the second side edge 23 of the blade segments 8, 8a, 8b, i.e., the second wall 14b of the opening 14, are inclined at a substantially different angle from one another at least in each opening 14 of the turbine segments 8, 8a, 8b, at least over a portion of their thickness direction.

[0051] According to this embodiment, the inclination angle of the first side edge 22 and the inclination angle of the second side edge 23 of the blade segments 8, 8a, 8b are different from each other at least in each opening 14 of the blade segments 8, 8a, 8b over at least a portion of the thickness of the side edges 22, 23, thus departing from the embodiment of Figure 5 in which the side edges 22, 23 are inclined at substantially equal angles. Embodiments disclosed herein also include embodiments in which only one of the side edges 22, 23 of the blade segments 8, 8a, 8b is inclined relative to the normal to the refining surface 9 of the blade segment 8, 8a, 8b.

[0052] An advantage of this embodiment is the variation in cross-sectional opening area of ​​opening 14 along at least a portion of walls 14a, 14b, which provides an additional means for influencing the flow of material to be purified through opening 14 and into purification chamber 12.

[0053] According to one embodiment, at least one side edge is curved at least in a portion of the thickness of the blade segment, at least in each opening of the blade segment. According to this embodiment, the first side edge 22 of the blade segment 8, 8a, 8b, i.e., the first wall 14a of the opening 14, and / or the second side edge 23 of the blade segment 8, 8a, 8b, i.e., the second wall 14b of the opening 14, is curved at least in a portion of the thickness of the blade segment, at least in each opening of the blade segment 8, 8a, 8b.

[0054] 6 shows a schematic partial cross-sectional end view of a second embodiment of the blade segments 8, 8a, 8b of FIGS. 2, 3 and 4 taken along section line AA shown in FIGS. 3 and 4, omitting the feed groove 29. In the embodiment of FIG. 6, both the first side edge 22 and the second side edge 23 of the blade segments 8, 8a, 8b are similar to the walls 14a, 14b of FIG. 5, except that they are curved in their thickness direction.

[0055] This curved configuration of the blade segment side edges 22, 23 in Figure 6 also provides a slope of the walls 14a, 14b of the opening 14 which has the effect of providing smooth guidance for the pulp and thus improving its feeding through the opening 14 into the refining chamber 12 between the stator 3 and the rotor 6 when the refiner 1 is in use.

[0056] Figure 7 is a schematic, partially cross-sectional end view of a third embodiment of the blade segments 8, 8a, 8b of Figures 2, 3 and 4 taken along section line AA shown in Figures 3 and 4. The feed groove 29 has also been omitted from Figure 7.

[0057] 7, at least in each opening of the blade segments 8, 8a, 8b, a bevel 31 is disposed on the background surface 26 at the second side edge 23 of the blade segment 8, 8a, 8b. In other words, the blade segments 8, 8a, 8b include a bevel 31 on the background surface 26 of the blade segment body 24 at least on the second wall 14b of each opening 14. The bevel 31 extends from the second side edge 23 of the blade segment 8, 8b substantially toward the intended direction of rotation RD of the blade segment 8, 8a, 8b when the blade segment 8, 8a, 8b is attached to the rotor 6, or in other words, toward the first side edge 22 of the blade segment 8, 8a, 8b. The bevel 31 may extend over the entire extent of the second side edge 23 of the blade segment 8 between the inner edge 20 and the outer edge 21 of the blade segment 8, 8a, 8b, but the bevel 31 extends at least substantially over the extent of the opening 14 in the direction between the inner edge 20 and the outer edge 21 of the blade segment 8, 8a, 8b.

[0058] The bevel 31 may be formed, for example, by removing material of the blade segments 8, 8a, 8b on the side of the background surface 26 at the second side edge 23 of the blade segments 8, 8a, 8b at least in each opening 14. According to another example, the bevel 31 may be formed by removing material of the blade segments 8, 8a, 8b on the side of the background surface 26 at the second side edge 23 of the blade segments 8, 8a, 8b at least in each opening 14.

[0059] The slope 31 also provides a height difference between the background surface 26 at the first side edge 22 of the blade segments 8, 8a, 8b and the background surface 26 at the second side edge 23 of the blade segments 8, 8a, 8b at least at each opening 14 of the blade segments 8, 8a, 8b on the side of the background surface 26 of the blade segments 8, 8a, 8b, so that the first side edge 22 of the blade segments 8, 8a, 8b extends further in the direction in which the background surface 26 of the blade segments 8, 8a, 8b faces than the second side edge 23 of the blade segments 8, 8a, 8b. As in the embodiments of Figures 5 and 6, the height difference provided by the slope 31 forms a guide element or guide surface on the side of the background surface 26 of the blade segments 8, 8a, 8b at least at the first side edge 22 of the blade segments 8, 8a, 8b at the opening 14, which enhances the transport of the material to be purified from the side of the background surface 26 of the blade segments 8, 8a, 8b through the opening 14 to the side of the forward surface 25 of the blade segments 8, 8a, 8b, i.e., to the purification surface 9 of the blade segments 8, 8a, 8b or into the purification chamber 12 between the stator 3 and the rotor 6.

[0060] 2, 3, and 4, the feed grooves 29 are arranged to extend from the openings 14 located in the first side edges 22 of the blade segments 4, 4a, 4b, 8, 8a, 8b toward at least one other edge of the blade segments, in the illustrated embodiment toward the second side edges 23 of the blade segments, so that the feed grooves 29 intersect the blade bars 27 and the blade grooves 28. The feed grooves 29 have a first end 29a at the openings 14 and a second end 29b facing away from the openings 14. The feed grooves 29 form a flow connection with the respective recessed or slit-like openings 14 in the first side edges 22, so that the material to be refined and fed through the openings 14 from the background surface 26 side of the blade segment toward the front surface 25 of the blade segment enters the feed grooves 29 and flows along the feed grooves 29 toward the central portion of the blade segments, thereby feeding the material to be refined across the refining surfaces 5, 9. At the same time, the force caused by the rotation of the rotor 6 acts on the material flowing into the feed grooves 29, forcing the material from the feed grooves 29 and away from the blade grooves 28 remaining between the blade bars 27 onto the top surfaces of the blade bars 27, thus dispersing the material to be purified on the refining surfaces of the blade segments. It should be noted that the feed grooves 29 are not an essential feature of the blade segments, but rather a feature that may be utilized in some embodiments of the blade segments to improve the distribution of the material to be purified on the refining surfaces of the blade segments.

[0061] In the embodiment of the blade segment of Figures 2, 3 and 4, the feed groove 29 is arranged to intersect the blade bar 27 and the blade groove 28 at an angle. According to this embodiment, the feed groove 29 intersects the blade bar 27 and the blade groove 28 at an angle of preferably 90 to ±45 degrees. The effect of this embodiment is a better distribution of the material to be purified from the feed groove 29 to the blade groove 28 and onto the top surface of the blade bar 27, i.e., into the purification chamber 12.

[0062] According to one embodiment of the blade segment, the feed groove is curved along its elongation direction. The second end of the curved feed groove may be at the same or a different position in the longitudinal direction of the blade segment as indicated by the longitudinal axis LA of the blade segment as the first end of the feed groove. An advantageous effect of this embodiment is that the material to be fed to the refining surface of the blade segment can be substantially freely directed to a desired portion of the refining surface.

[0063] Referring back to the feed groove 29 and the embodiment of Figure 4, the blade bars 27 of the blade segments 8a, 8b are interlaced at the feed groove 29. The blade bars 27 are interlaced at the feed groove 29 such that, when viewed in the direction of the longitudinal axis LA of the blade segments, the ends of the blade bars on either side of the feed groove are interlaced at the feed groove 29.

[0064] According to one embodiment, the oppositely oriented interlaced blade bars include downwardly sloping ends arranged to form upwardly directed feed channel openings.

[0065] The interlacing of the blade bars in the feed groove provides a strong blade bar configuration in which the interlaced blade bars support each other in the feed groove, thereby preventing buckling of the blade bars during feeding.

[0066] It will be obvious to those skilled in the art that with the advancement of technology, the inventive idea can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims. [Prior art documents] [Patent documents]

[0067] [Patent Document 1] European Patent No. 3401439B1

Claims

1. 1. A blade segment for a refiner for refining fibrous material, comprising: a body having a front surface and a background surface; a first edge and a second edge; a first side edge and a second side edge opposite the first side edge, the first side edge and the second side edge extending between the first side edge and the second side edge; a refining surface including a blade bar and a blade groove on the forward surface of the blade segment; at least one opening in the side edge extending through the entire thickness of the body of the blade segment toward the opposite side edge; a height difference exists between the background surface at the first side edge of the blade segment and the background surface at the second side edge of the opening of the blade segment on the side of the background surface of the blade segment; Blade segment.

2. 2. The blade segment of claim 1, wherein the background surface at the first side edge of the opening of the blade segment has a protrusion thereon to provide the height difference between the background surface at the first side edge of the opening and the background surface at the second side edge.

3. 3. A blade segment according to claim 1 or 2, characterized in that the background surface at the second side edge of the opening of the blade segment is beveled to provide the height difference between the background surface at the first side edge of the opening and the background surface at the second side edge.

4. A blade segment according to any one of claims 1 to 3, characterized in that at least one side edge is beveled at the opening over at least a portion of its thickness.

5. A blade segment according to any one of claims 1 to 4, characterized in that the side edges of the blade segment are inclined at substantially different angles to one another over at least a portion of their thickness.

6. A blade segment according to any one of claims 1 to 5, characterized in that at least one side edge of the blade segment is beveled at the opening over at least a portion of its thickness.

7. A blade segment according to any one of claims 1 to 6, characterized in that the blade segment is a rotor blade segment, the first side edge of the blade segment being a leading edge arranged to face towards the intended direction of rotation of the rotor of the refiner, and the second side edge of the blade segment being a trailing edge arranged to face towards the direction opposite to the intended direction of rotation of the rotor of the refiner.

8. A blade segment according to any one of claims 4 to 7, characterized in that at least the first side edge of the blade segment is inclined, over at least a portion of its thickness, towards the intended direction of rotation of the refiner rotor at the opening of the blade segment.

9. 9. A blade segment according to claim 4, wherein both the first side edge of the blade segment and the second side edge of the blade segment are inclined, over at least a portion of their thickness, towards the intended direction of rotation of the refiner rotor at the opening of the blade segment, and the inclination angle of the second side edge is different from the inclination angle of the first side edge.

10. A blade segment according to any one of claims 4 to 9, characterized in that at least one side edge of the blade segment is beveled at the opening over at least a portion of its thickness.

11. 11. A blade segment according to any one of claims 1 to 10, characterized in that the blade segment includes at least one feed groove in the refining surface, the feed groove extending from the opening and intersecting the blade bar and the blade groove for feeding the material to be refined across the refining surface.

12. 12. The blade segment of claim 11, wherein the feed groove is positioned to intersect the blade bar and the blade groove at an angle of between 90 degrees and ±45 degrees.

13. 1. A refiner for refining fibrous material, comprising: Characterised in that it comprises at least one blade segment according to any one of claims 1 to 12, Refiner.

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