Patent Application
20240150962
This application claims priority on FI 20226007, filed Nov. 8, 2022, the disclosure of which is incorporated by reference herein.
Not applicable.
The invention relates to the refining of fibrous material and especially to a method for manufacturing a refining segment, and a refining segment for refining fibrous material.
Refiners used for refining fibrous material, such as a wood material containing lignocellulose or another fiber material suitable to be used for manufacturing pulp, paper, or paperboard, for example, comprise typically a stator and a rotor opposite to each other, the rotor rotating about its central axis, thereby turning relative to the stator. The stator and the rotor comprise refining surfaces provided with refining bars and refining grooves therebetween, the refining bars being intended to defiber and refine the material to be refined and the refining grooves being intended to convey the material to be refined forward along the refining surfaces. The refining surface of the stator and the rotor may be formed of several refining segments fastened to a body of the respective stator/rotor. In that case the complete refining surface of the respective stator/rotor is thus formed of the refining surfaces of several refining segments fastened next to each other in the respective stator/rotor.
A typical method for manufacturing the refining segment is casting, wherein melt metal, such as iron or steel, is poured into a mould shaped to provide a design for the refining surface on top of a body of the refining segment, the body of the refining segment and the refining surface on top of it forming a uniform combined cast segment. After the metal has hardened, the cast refining segment is removed from the mould, and the refining segment is ready for use, or the refining bars and the refining grooves may additionally be machined to provide the finished intended design of the refining surface.
A problem relating to the manufacturing of the refining segments by casting is that due to a limited mould construction accuracy in casting, it is in practice impossible to provide very dense refining surface configurations, i.e., refining surface configurations wherein the width of the refining bars and refining grooves are in a range of only one or a few millimetres. Other problems in this kind of casted refining segments are incomplete filling of the refining bars and high surface roughness of the refining bars, which are not possible to complete or make smoother after casting.
According to a prior art method for manufacturing a refining segment, bars made of metal strips and providing the refining bars of the refining segment are set on top of a back plate at a distance from each other and the refining bars are welded to the back plate. With this method the machining of the refining bars and the refining grooves after casting may be avoided and a very dense refining surface configuration is also possible. However, a problem relating to the manufacturing of the very dense refining surface configurations by this way is for example an amount of the welding work which can reach up to tens of kilometres to provide a complete refining surface of an entire refining element.
Therefore, there is a need to provide an alternative solution for manufacturing refining segments, especially for manufacturing refining segments with very dense refining surface configurations.
An object of the present invention is to provide a novel method for manufacturing a refining segment and a novel refining segment for refining fibrous material.
The invention is based on implementing refining bars in a refining segment of a profiled wire having a width of a bottom of the profiled wire different from a width of a top of the profiled wire and on arranging at least one set of the profiled wires next to each other and substantially immovable with respect to each other to form at least one refining bar element. The at least one refining bar element is fastened onto a back plate, wherein said back plate forms a body of the refining segment, by applying at least one solidifying substance between the at least one refining bar element and the back plate.
The method disclosed provides an efficient way, especially in view of manufacturing costs and time, to manufacture refining segments especially with very dense refining surface configurations.
In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings.
For the sake of clarity, the figures show some embodiments of the invention in a simplified manner. Like reference numerals identify like elements in the figures.
The refiner 1 of
The refiner 1 further comprises a rotor 6 of the refiner 1. The rotor 6 comprises a rotor frame 7. The rotor frame 7 is connected to a rotatable shaft 10 used to rotate the rotor 6 about its central axis. The rotor 6 further comprises two or more rotor refining segments 8 supported to the rotor frame 7, each rotor refining segment 8 comprising refining bars and refining grooves therebetween. The refining bars and the refining grooves in each rotor refining segment 8 form a refining surface 9 of the respective refining segment 8, the refining surface 9 of each rotor refining segment 8 thereby providing a part of a refining surface of the rotor 6. A complete refining surface of the rotor 6 is formed of the refining surfaces 9 of a necessary number of the rotor refining segments 8 fastened next to each other in the rotor 6 so that the complete refining surface 9 extending over the whole circumference of the rotor 6 is provided. For the sake of clarity, both the refining surface of each single rotor refining segment 8 as well as the complete refining surface of the rotor 6 are herein denoted with the same reference sign 9.
The fibrous material to be refined is fed into the refiner 1, into a refining gap 11 remaining between the stator 2 and the rotor 6 opposite to each other via a feed channel 12 in a manner shown by arrow F. The refined material is removed via a discharge channel 13 from the refiner 1, as schematically shown by arrow D. The fibrous material to be refined is fed into the refiner 1 in a form of pulp suspension being a mixture comprising at least water and virgin fibrous material and/or recycled fibrous material.
The refining segment 4, 8 comprises an inner end edge 15 or a first end edge 15 being intended to be directed towards an inner periphery of the stator 3 or the rotor 6. The refining segment 4, 8 further comprises an outer end edge 16 or a second end edge 16 opposite to the inner end edge 15 in a longitudinal direction of the refining segment 4, 8, the outer end edge 16 being intended to be directed towards an outer periphery of the stator 3 or the rotor 6. The refining segment 4, 8 further comprises a first side edge 17 extending from the inner end edge 15 of the refining segment 4, 8 up to the outer end edge 16 of the refining segment 4, 8. The refining segment 4, 8 further comprises a second side edge 18 opposite to the first side edge 17 in a circumferential direction of the refining segment 4, 8. The second side edge 18 extends from the inner end edge 15 of the refining segment 4, 8 up to the outer end edge 18 of the refining segment 4, 8. The inner 15 and the outer 16 end edges together with the first 17 and second 18 side edges contribute to define a periphery 14 of the refining segment 4, 8. In conical refiners, typically, the radially smaller end of the stator/rotor is considered to refer to the inner periphery of the stator/rotor and the radially larger end of the stator/rotor is considered to refer to the outer periphery of the stator/rotor.
The refining segment 4, 8 of
The refining segment 4, 8 may further comprise one or more nondisclosed fastening holes extending through the back plate 19 and intended to receive proper fastening members, such as bolts, for fastening the respective refining segment 4, 8 to the frame 2 of the refiner 1 or to the frame 7 of the rotor 6.
Referring to
In the embodiment of
The profiled wires 22 in
The set of the profiled wires 22 arranged next to each other such that they are arranged at the distance from each other and substantially immovable with respect to each other form a refining bar element 24 that is intended to form at least a part of a refining surface 5, 9 of a refining segment 4, 8. In the embodiment of
Referring to
According to an embodiment, at least one layer of the solidifying substance 25 is applied on top of the back plate 19 in a solid form. Thereafter heat is applied to the at least one layer of the solidifying substance 25 to transform the at least one layer of the solidifying substance 25 having originally been in a solid form into a molten form, whereafter the refining bar element 24 is set on top of the solidifying substance 25 being in the molten form, whereby the solidifying substance 25 remains between the back plate 19 and the bottoms 22a of the profiled wires 22 and also infiltrates between the bottoms 22a of the adjacent profiled wires 22 in the refining bar element 24.
According to an embodiment, at least one layer of the solidifying substance 25 is applied on top of the back plate 19 in a solid form and the refining bar element 24 is set on top of the solidifying substance 25 still being in the solid form. Thereafter heat is applied to the at least one layer of the solidifying substance 25 to transform the at least one layer of the solidifying substance 25 into the molten form, whereby the solidifying substance 25 remains between the back plate 19 and the bottoms 22a of the profiled wires 22 and also infiltrates between the bottoms 22a of the adjacent profiled wires 20 in the refining bar element 24.
According to an embodiment, at least one layer of the solidifying substance 25 is applied on top of the back plate 19 in a molten form. Thereafter the refining bar element 24 is set on top of the solidifying substance 25 being in the molten form, whereby the solidifying substance 25 remains between the back plate 19 and the bottoms 22a of the profiled wires 22 and also infiltrates between the bottoms 22a of the adjacent profiled wires 22 in the refining bar element 24.
In any of the three embodiments disclosed above for fastening the refining bar element 24 on top of the back plate 19, additional solidifying substance 24 may be applied in a molten form may be applied between the bottoms 22a of the profiled wires 22 if necessary.
The at least one substance 25 is thus brought, in some of its use situation, to a molten form, i.e., to a form of liquid suspension, but over time it becomes solidified or hardened. The solidification or hardening of the at least one substance 25 may be intensified, depending on the composition of the at least one substance 25, by cooling or heating it. The at least one substance 25 may be used to create totally complete joints between the profiled wires 22 and the refining segment back plate 25, as well as between the adjacent profiled wires 22, because in the molten form the at least one substance 25 can also find its way up to all voids between the profiled wires 22 and the refining segment back plate 25, as well as between the adjacent profiled wires 22. This means that the bonding of the refining bars to the back plate is complete, i.e., there are 100% complete joints between the refining bars and the back plate, which provides expected refining effects with sufficient evenness and strength. The disclosed solution thus allows to avoid a problem of incomplete fastening of the refining bars to the back plate of the refining segment possibly appearing in prior art solutions involving for example welding of the refining bars to the back plate, which incomplete fastening may result in uneven refining effects or wearing of the refining bars.
According to an embodiment, the at least one solidifying substance 25 comprises metal, whereby the profiled wires 22 become metallurgically bonded to each other and to the back plate 19. After the at least one substance 25 has solidified or hardened, the profiled wires 22 and the back plate 19 form a substantially uniform structure, although some kind of border line between the solidified substance 24 and the material of the profiled wire 22 and/or the back plate 19 may be visible in the cross section of the refining segment 4, 8. After the at least one substance 25 has solidified or hardened, the at least one substance 25 constitutes for its part also abrasion resistant surfaces in the refining segment 4, 8.
According to an embodiment, the at least one solidifying substance 25 is braze, i.e., a metal alloy comprising for example iron, copper, nickel and/or silver. The composition of the braze is thus different from the composition of metal material of the profiled wires 22 or of the back plate 19. A melting temperature of typical braze material is about 450° C., whereby the melting temperature of the braze material is substantially low when considering the melting of the braze material, and thereby it does not have effect on the properties of the profiled wires 22 or the back plate 19 of the refining segment 4, 8 that are manufactured from a material with a higher melting temperature. The melting temperature of the braze material is still high enough so that the fastening of the profiled wires 22 to the finished refining segment 4, 8 will not become weakened by temperatures appearing in the refiner during refining. The braze thus forms one kind of solidifying or hardening metallic substance that can be used as a filler metal for joining the profiled wires 22 to the back plate 19.
According to an embodiment, the at least one solidifying substance 25 comprises glue. The glue may for example be plastic based or resin-based glue.
The disclosed solution is very usable for manufacturing refining segments with very dense refining surface configurations, i.e., the refining surface configurations with a width of the refining bars and a width of the refining grooves in a range of only less one or a few millimeters, these very dense refining surface configurations being in practice impossible or at least unprofitable to manufacture by casting, or very laborious to manufacture by welding refining bars to the back plate one at a time. When the refining bars in the refining segment are implemented of a profiled wire, the profiled wire with a desired cross-section may be manufactured as a single piece of undetermined length, and the profiled wire will only be cut to pieces of suitable length(s) with desired end profiles. The implementation of the refining bars of a profiled wire also solves the problems of incomplete filling of the refining bars and high surface roughness of the refining bars appearing in the refining segments made by casting. The implementation of the refining bars of the profiled wire with a width of the bottom of the profiled wire being different from a width of the top of the profiled wire, such as of the profiled wire with the width of the bottom of the profiled wire being greater than the width of the top of the profiled wire as shown in the figures has the effect that the bottoms of the refining grooves will be also partly implemented of the profiled wires. This has the effect that the bottoms of the refining grooves have substantially smooth surface structures providing substantially constant flow behavior for the flow of the fibrous material in the refining grooves. The effect of the bottoms of the refining grooves being partly implemented of the profiled wires is also that the bottom of the refining groove is implemented only of the bottoms of the adjacent profiled wires and one single seam formed of the said substance, such as of the braze, infiltrated therebetween, whereby no other measures for implementing the refining grooves are not necessary, and at the same time, the number of the seams in the refining segment implementation is minimized, thereby providing a strong structure of the refining surface segment.
The refining bar element 24 comprising the profiled wires pre-fastened to each other and/or to the support platform 26 can be manufactured to exact dimensions for example in a jig before fastening the refining bar element 24 to the back plate 19 of the refining segment 4, 8. The fastening of the refining bar element 24 to the back plate 19 by the at least one solidifying substance 25 removes a need for laborious welding work for fastening the refining bars 20 to the back plate 19 one at a time. The method disclosed thus provides an efficient way, especially in view of manufacturing costs and time, to manufacture refining segments especially with very dense refining surface configurations.
Referring to
It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept 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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20226007 | Nov 2022 | FI | national |
