Background of the invention

[0001] The invention relates to a neck element of a disc filter sector, which may be attached to the sector in such a manner that it forms the neck element of the sector.

[0002] The invention further relates to a method for forming a neck element.

[0003] The field of the invention is described in closer detail in the preambles of the independent claims of the application.

[0004] In the mining industry, metal refining, chemical industry, as well as in the processes of foodstuff and medicine production, for example, a need exists for solid-liquid filtering in which liquid and solid particles are separated from a mixture comprised of solid material and liquid. A disc filter is one of the solid-liquid filters appropriate for the purpose. A disc filter has a plurality of substantially triangular sector elements arranged side by side so that the sectors form a discoidal structure. On top of each sector, a filter bag made of filtering cloth may be arranged, which may act as the filtering element. A sector may comprise a blade part and a neck element attached to each other. However, drawbacks have been detected in the present neck elements.

Brief description of the invention

[0005] It is the object of this invention to bring forth a new and improved neck element of a disc filter sector and a method for forming a neck element.

[0006] The neck element according to the invention is characterized in that the neck element is formed of two halves coupled to each other.

[0007] The method according to the element is characterized by forming two halves both of which are provided with joint surfaces; and

[0008] assembling the neck element by arranging the joint surfaces of the halves against each other and fastening the halves to each other immovably.

[0009] The idea of the disclosed solution is that the neck element is formed of two halves which are arranged against one other and fastened together. [0010] One of the benefits of the disclosed solution is that a neck element formed of two halves is easier to manufacture compared with a structure where the neck element is one, uniform piece comprising an internal space difficult to form. Furthermore, the use of two separate halves allows the use of different kind of manufacturing techniques and provides the chance to more freely shape, process and equip the inner halves of the neck element than in a part formed as a uniform part.

[0011] The idea of an embodiment is that the neck element is formed of two halves that are mutually identical. This embodiment makes the manufacture simpler and reduces manufacturing costs.

[0012] The idea of an embodiment is that the halves of a neck element are manufactured by injection moulding from a plastic material. The casting mould that is used to make a half may be considerably simpler than the casting mould for a uniform neck element, because a half does not comprise an internal space, which would require the use of a core to form. In addition, the casting mould of a half is smaller in size. A particular advantage is achieved in case a neck element is formed of two identical halves. In such a case, all that is needed is one casting mould, by means of which the halves can be moulded.

[0013] The idea of an embodiment is that the neck element half is formed by moulding, by using at least two different plastic materials. When needed, two, three, or even more plastic materials may be used. Furthermore, it is possible to use plastic materials provided with different additives in different portions of a half. In such a case, the body, for example, may be fibre- reinforced plastic material and the wear surface inside unreinforced, wear- resistant plastic material.

[0014] The idea of an embodiment is that the neck element half is formed of injection moulding from a plastic and that during the casting, one or more inserts are integrated into the half. An insert may be, for example, a strengthening piece, a fastening means, or a wear piece. An insert may be, for example, plastic, composite material, or metal.

[0015] The idea of an embodiment is that a half comprises an outer surface and an inner surface. Further, the half comprises a body which forms the side of the outer surface of the half and part of the inner surface. The inner surface additionally has one or more functional portions, permanently fastened to the body. [0016] The idea of an embodiment is that the body of a neck element half is of a first plastic material, and the inner surface has one or more functional portions of a second plastic material.

[0017] The idea of an embodiment is that a support element is integrated on the inner surface of the neck element half, which protrudes from the inner surface of the half and which is arranged to form an internal support for the neck element. The support element in such a case is a functional portion formed on the inner surface of the half and permanently fastened on the body of the half. The support element may be of the same or different material as the body. The half according to this embodiment may be formed by injection moulding in one go, and the material for the support element may be selected with wear resistance in mind.

[0018] The idea of an embodiment is that a wall portion is integrated on the inner surface of the neck element half, which forms at least part of the inner surface of the half. The wall portion or wall surface is in such a case a functional portion arranged on the inner surface of the half and permanently fastened to the body of the half. The functional wall may be of the same or different material as the body. The half according to this embodiment may be formed by injection moulding in one go, and the material for the wall surface may be selected with wear resistance, friction characteristics, or thermal conductivity in mind.

[0019] The idea of an embodiment is that a wall portion is integrated on the inner surface of the neck element half, which covers the entire inner surface of the half. In such a case, the half has a two-layer structure where a first material forms the body and outer surface of the half, and in which a second material forms the inner surface of the half.

[0020] The idea of an embodiment is that both halves of the neck element comprise joint surfaces on the portion of their side edges. In such a case, the joint surfaces of the halves form dividing joints at both side edges of the neck element.

[0021] The idea of one embodiment is that the halves of the neck element have planar joint surfaces. In such a case, the planar joint surfaces of the halves are arranged against each other in the neck element and form butt joints.

[0022] The idea of an embodiment is that the joint surfaces of the halves are positioned in an interlacing manner at said dividing joints. The joint surfaces may be provided with tongue - groove surfaces that fit in each other, whereby the dividing joint has a type of tongue-and-groove joint that accepts transversal forces and may form a tight coupling. The first side edge of a half may be provided with a groove and the opposite, second side edge with a tongue or similar protruding part. When two identical halves like this are arranged against each other, the grooves and tongues will be positioned in each other at both side edges of the neck element formed. Instead of the tongue-groove surfaces, the joint surfaces may comprise collar-like surfaces that also have interlacing portions.

[0023] The idea of an embodiment is that the joint surfaces of the halves are provided with locking surfaces so that a form lock is established between the joint surfaces arranged against each other. This form lock may keep the halves fastened to each other without any specific fastening means, or alternatively the form lock participates in such a fastening where separate fastening means are additionally used.

[0024] The idea of an embodiment is that the joint surfaces of the halves are glued to each other. Gluing alone may provide an adequate fastening strength, or some other locking may be applied in addition to gluing, such as form locking or separate fastening means.

[0025] The idea of an embodiment is that the joint surfaces of the halves are welded together. The welding may be carried out as ultrasonic welding, for example. Further, a welding method may be used where the joint surfaces are mechanically pressed against each other during welding.

[0026] The idea of an embodiment is that the halves are fastened together by means of screws. In such a case, the joint surfaces may be provided with flanges or edge portions, at which the fixing screws may be arranged. The flanges form the portions that protrude from the outer surface of the neck element.

[0027] The idea of an embodiment is that a neck element half is provided with one or more separate additional elements prior to the assembly of the neck element. It is far easier to fix a retrofit additional element to the inner surface of a half than on a surface inside a neck element formed as a uniform piece. The additional element may be, for example, a support element, wear piece, guide surface or another element by means of which a neck element may be tailored to suit a particular usage application. [0028] The idea of an embodiment is that a neck element is provided with at least one, separate support element, which is arranged inside the neck element and which participates in the fastening of the halves. There may be a fixing screw, for example, at the support element, by means of which the halves are fastened together.

[0029] The idea of an embodiment is that the inner surface of a neck element half is provided with predesigned one or more fastening surfaces that may, if need be, receive a separate additional element. The fastening surface may have support surfaces that may support the additional element to be fastened in one or more directions. The fastening in place of the additional element so that is does not move may be secured by means of a screw, adhesive, or similar fastening means. Furthermore, the fastening surfaces and additional element may be shaped so that a mutual form lock is established between them, whereby separate locking means are not necessarily needed at all.

[0030] The idea of an embodiment is that the inner surface of a neck element half is coated with at least one layer of coating before the neck element is assembled.

[0031] The idea of an embodiment is that the inner surface of a neck element half is machined by chip removal or machining that utilizes wavelike energy, such as by means of a laser beam. On the inner surface of a half, patterning affecting flow characteristics, or a fixing point for an additional element can be made.

[0032] It should still be mentioned that the embodiments described in the above and their features can be combined whereby various characteristics combinations may be achieved.

Brief description of the figures

[0033] Some embodiments are explained in more detail in the accompanying drawings, in which

[0034] Figure 1 is a schematic representation of a disc filter,

[0035] Figure 2 is a schematic representation of a sector that comprises a blade element and neck element fastened together,

[0036] Figure 3 is a schematic and sectioned view of a sector and its securing to a disc filter,

[0037] Figure 4 is a schematic representation of a joint solution of a blade element and neck element, [0038] Figure 5 is a schematic representation of a neck element formed of two halves as seen from the side of its mouth,

[0039] Figure 6 is a schematic representation of a neck element formed of two halves as seen from the direction of a blade element,

[0040] Figure 7 is a schematic representation of a neck element half as seen from the side of its inner surface,

[0041] Figure 8 is a schematic representation of a neck element half, in connection with which different kinds of functional elements are shown,

[0042] Figure 9 is a schematic representation of a tongue-and- groove joint between the halves of a neck element,

[0043] Figure 10 is a schematic representation of the collar surfaces in the joint surfaces of neck element halves and the joining together of the halves,

[0044] Figure 1 1 is a schematic representation of an interlacing joint of the collar surfaces of the neck element halves and transversal lock thereof,

[0045] Figure 12 is a schematic representation of the fastening flanges on the joint surfaces of neck element halves and their joining together by a fastening element,

[0046] Figure 13 is a schematic representation of the fastening flanges on the joint surfaces of neck element halves and their joining together by a welded seam, and

[0047] Figure 14 is a schematic representation of planar joint surfaces of neck element halves, fastened together by an adhesive joint.

[0048] For the sake of clarity, the figures show some embodiments in a simplified manner. In the figures, like reference numerals identify like elements.

Detailed description of some embodiments

[0049] Figure 1 shows a disc filter 1 , which comprises a basin 2 into which a suspension consisting of solid matter and liquid is fed to be processed, from a feed channel 3. Further, a body part 4 rotated around a horizontal axis is part of the disc filter 1 . On the outer periphery of the body part 4, a plurality of substantially triangular sectors 5 are arranged side by side, whereby the sectors 5 form a relatively narrow discoidal structure around the body part 4. One body part 4 may comprise a plurality of such discoidal structures arranged at an axial distance from each other. The triangular flanks 6 in each sector 5 have holes 7. On top of the sectors 5, a filter bag 8 made of filter cloth suitable for solid-liquid filtering may be arranged, acting as the filtering layer. The body part 4 of the disc filter is rotated around its longitudinal axis A, whereby each sector 5 in turn is submerged in a suspension 9 in the basin 2. Through the body part 4, it is possible to create underpressure inside the sector 5 submerged in the suspension 9. In such a case, liquid can pass through the filter bag 8 and further inside the sector 5 through the holes 7 in the flank surface 6 of the sector. Inside the sector 5, the liquid, affected by the underpressure, flows to a neck part 12 of the sector and further out of the disc filter through the body part 4. Solid material, instead, will remain on the surface of the filter cloth 8, from where it may be removed by means of doctor blades 10 or pressure medium sprays to a discharge shaft 13 before the subsequent filtering cycle. Alternatively, the cloth is expanded by means of pressure in order to remove the solid material cake. It is additionally possible that a filter bag 8 formed of cloth is not arranged on the sector 5, but the flank surfaces of the sector 5 are provided with another filtering element.

[0050] Figures 2 and 3 illustrate the basic structure of the sector 5. The sector 5 comprises a blade part 1 1 and a neck part 12. The flanks 6 of the blade part 1 1 act as the filtering surfaces, which is why they are provided with holes 7. The neck part 12, on the contrary, has no holes, because no filtering takes part in it. The outermost end of the sector 5 has an end edge 16. The sector 5 is hollow, in other words, it has a space 17 inside of it, which extends from the end edge 16 all the way to a mouth 15 and which is confined by flanks 6 and side edges 14. The neck part 12 of the sector 5 is formed by a separate neck element 20, which is fastened to the innermost end of the blade part 1 1 .

[0051] Figure 4 shows a coupling of the blade part 1 1 and the neck element 20. The neck element 20 has a first end 23, a second end 24, conical flank surfaces 19, side edges 22, mouth 15, as well as connecting surfaces 27 and 28. The narrow end of the sector blade part 1 1 may be pushed inside the first end 23 of the neck element 20, whereby the blade part 1 1 and neck part 12 are partially within each other. The blade part 1 1 may have form locking means, such as locking projections 25, which may protrude into locking slots 26, which show in Figure 6, in the neck element 20. The wider first end 23 of the neck element 20 has the first connecting surfaces 27, which connect to the connecting surfaces 28 that are at the end of the blade part 1 1 . The connecting surface 28 of the blade part 1 1 may comprise shaped surfaces whereby the first connecting surfaces 27 may be shaped in the corresponding way. At the other end 24 of the neck element 20, that is, at the narrow end at the side of the mouth 15, there are second connecting surfaces 29, by means of which the neck element 20 may be connected to the disc filter.

[0052] As may be seen from Figures 5 and 6, the neck element 20 is comprised of two halves 31 fastened together. The halves 31 comprise joint surfaces 33 which are to be joined together and which form division seams 32 at the side edges 22 in the neck element 20. The halves 31 of the neck element 20 may be mutually identical, which makes them easier to manufacture. Alternatively, two dissimilar halves 31 are used, which have been made dissimilar from the start in connection with manufacturing them, or which are based on similar prefabricated halves, but which have been modified to differ from each other before the neck element 20 was assembled.

[0053] Figure 6 also shows the body 34 of a half 31 , inner surface 35, and outer surface 36.

[0054] Figure 7 shows a half 31 of the neck element 20 as seen from the direction of the inner surface 35 of the half. The side edges 22 of the half 31 are provided with joint surfaces 33. The joint surfaces 33 may be the plane surfaces shown in the figure, or alternatively the joint surfaces 33 may be form surfaces. Later on, Figures 9 - 1 1 show possible form surfaces. It should be mentioned that a form surface may comprise curved surfaces and, in addition, form shapes arranged against each other may comprise locking surfaces that may establish a form or friction lock.

[0055] As Figure 7 demonstrates, the structure of the half 31 is relatively simple, and it is open without internal spaces. This is why the half 31 is well suited for injection moulding, making it possible to manufacture good- quality halves cost-effectively.

[0056] Figure 8 shows a half 31 of the neck element 20, the inner surface 35 of the half being provided with functional elements. The inner surface 35 may have one or more support elements 18 by means of which the opposite flank surfaces 19 of the neck element can be supported to each other. In such a case, the support element 18 aims to prevent the inner surfaces of the neck element 20 from moving with respect to each other as a result of the effects caused by the pressure difference between the outer and inner surfaces of the neck element during filtering. The support element 18 may be formed at the same time as the half 31 is formed. The height of the support element 18 from the inner surface 35 may be dimensioned to extend to the same plane as the joint surfaces 33, or alternatively the support element may be dimensioned to extend against the inner surface of the opposite half.

[0057] The support element 18 may take part in the fastening between the halves 31 of the neck element 20 together with the joint surfaces 33. The outermost end of the support element 18 may be fastened by glue, for example, to the end of the opposite support element or the flank surface of the opposite half. It is further possible that there is a hole in the flank of the opposite half, and that the support element 18 extends through this hole to the side of the outer surface of the flank in the opposite half. In such a case, a screw or similar fastening means can be fastened to the outermost end of the support element 18, or the outermost end of the support element 18 may be flattened or welded against the outer surface of the flank in the opposite half.

[0058] The support element 18 may be an elongated rib whose longitudinal axis is on the centre axis of a flow channel 30. On the other hand, there may be a plurality of support elements 18. For example, in Figure 8, there are three rib-like support elements, and their positioning may follow the triangular shape of the flank 19 whereby good support may be established for the entire area of the flank 19. The elongated support elements 18 may be so directed that their longitudinal axes point towards the mouth 15.

[0059] Figure 8 shows still another possible support element 38, which may be a piece manufactured separately and, prior to the assembly of the neck element 20, fastened to the inner surface 35 of the half 31 . The support element 38 may be pin-like piece. Further, the support element 38 may be a tubular piece, whereby a fixing screw or similar mechanical fastening means can be arranged through its internal space to fasten the halves 31 of the neck element 20.

[0060] Further, the functional portion on the inner surface 35 of the half 31 may be a wall portion 37, which may form a restricted part of the inner surface 35. The wall portion 37 may be located at the place where wear is the heaviest. Alternatively, the wall portion 37 may cover the entire inner surface 35. The wall portion 37 may be formed simultaneously with the body 34. The thickness of the wall portion 37 may be determined on a case-by-case basis. The wall portion 37 may extend all the way to the outer surface 36 of the half 31 , whereby it may also form a part of the outer surface 36 of the half 31 . On the other hand, the wall portion 37 may be relatively thin as regards its thickness. [0061] It is further possible to make a fixing point 39, which may be provided with an additional element, on the inner surface 35 of the half 31 in connection with moulding it. Alternatively, the fixing point 39 may be machined on the inner surface 35 after moulding. As the half 31 has an open structure, it is quite simple to make required modifications or coatings on its inner surface 35.

[0062] Figure 8 further shows that the half 31 may be provided with an insert 48, which connects as an integrated part of the structure during injection moulding. The insert 48 may be wear piece, for example, forming a part of the inner surface 35 of the half 31 . Alternatively, the insert may be a fastening piece, allowing the fastening of the replaceable wear piece, for example, to the flow channel.

[0063] Figures 9 and 10 show, in a heavily simplified way, how the halves 31 of the neck element 20 are fastened together. The opposite side edges 22 of the halves 31 have joint surfaces 33, reversely formed with respect to each other. This makes it possible to form the neck element 20 by using two, identical halves 31 . When the half 31 is turned in the direction R, the mutually compatible joint surfaces 33 can be made to match. After this, the halves 31 may be arranged against each other in the direction P.

[0064] In Figure 9, a tongue-and-groove joint is established between the joint surfaces 33. The first joint surface features a groove 40 and the second a tongue 41 , which groove 40 and tongue 41 may be arranged to interlace with respect to each other.

[0065] In Figure 10, the joint surfaces 33 have collar surfaces 42, which are arranged to interlace with respect to each other.

[0066] Figure 1 1 shows a division seam 32, in which the collar surfaces 42 are arranged in an interlacing manner and locked immovably with respect to each other with a welded seam 43. Instead of welding, a screw or similar fastening means may be used. Locking may be carried out in the transversal direction with respect to the side edge 22 of the neck element 20.

[0067] Figure 12 shows a fastening means in which the joint surfaces 33 comprise fastening collars 44, which protrude from the side edge 22 of the neck element 20. The fastening collars 44 may be fastened to each other by means of a fastening means 45, such as a screw.

[0068] The solution shown in Figure 13 differs from Figure 12 in that the fastening collars 44 are fastened together with a welded seam 46. [0069] In Figure 14, the joint surfaces 33 between the halves 31 are fastened together by means of an adhesive 47.

[0070] Is should be mentioned that the fastening solutions presented in the above, that is, welding, mechanical fastening, and gluing, may also be combined so that a plurality of these solutions are simultaneously utilized in the joint surface. In addition to the fastening methods referred to in the above, it is further possible to make use of melting the joint surfaces together, as well as upsetting.

[0071] In some cases, features disclosed in this application may be used as such, regardless of other features. On the other hand, when necessary, features disclosed in this application may be combined in order to provide different combinations.

[0072] The drawings and the related description are only intended to illustrate the idea of the invention. Details of the invention may vary within the scope of the claims.