SCALLON HUB, CENTRIFUGE SCALLON AND FULLY SHELLED SCALLON CENTRIFUGE

Description

[0001] The invention relates to a screw hub for a centrifuge screw, comprising at least one monolithically shaped hub section, in particular at least two interconnected monolithically shaped hub sections, according to patent claim 1. Furthermore, the invention relates to a centrifuge screw with a screw hub according to the invention, according to patent claim 14. Furthermore, the invention relates to a solid bowl screw centrifuge according to patent claim 15.

[0002] Solid bowl centrifuges are characterized by a bowl with a closed or solid bowl. The bowl rotates at high speed, allowing a multiphase mixture contained within the bowl to be separated into at least one heavy phase and one light phase. The heavy phase is usually a solid phase, which is removed from the bowl by a screw, i.e., a centrifuge screw. For this purpose, the screw is mounted within the bowl so it can rotate relative to the bowl and has a screw flight. The screw flight is attached directly or indirectly to the screw hub and surrounds it in a spiral shape.

[0003] The screw flight sweeps along the inside or inner surface of the drum, thus conveying the heavy phase material to an axial end of the drum. At the end of the drum, the heavy phase material is discharged, for example, from a discharge cone. The multiphase mixture to be clarified is thus located between the inside of the drum and the screw hub.

[0004] In certain solid-bowl screw centrifuges, a large pond depth is desired, particularly for treatment-related reasons. However, the pond depth is limited by the diameter of the screw hub and the resulting buoyancy and sedimentation effects of the mixture to be clarified or the light phase.

[0005] On the other hand, there is a constant effort to develop a worm hub with sufficient or increased rigidity.

[0006] The pond depth can be increased by making the screw hub particularly permeable to media, but this may weaken the structure of the screw hub.

[0007] DE 10 2020 129478 A1 discloses a screw hub for a centrifuge screw, which has at least one monolithically formed hub section. The hub section has a peripheral wall and two end faces, with a plurality of openings formed in the peripheral wall.

[0008] The invention is therefore based on the object of providing a screw hub for a centrifuge screw which, due to an improved structural design, has increased rigidity and, at the same time, improved flow properties.

[0009] Furthermore, the invention is based on the object of enabling a modular construction of the screw hub, so that the size, in particular the longitudinal extent of the screw hub, can be designed in the sense of a modular principle.

[0010] Furthermore, the invention is based on the object of specifying a screw hub and a solid bowl screw centrifuge.

[0011] According to the invention, this object is achieved with respect to the screw hub by the subject matter of claim 1. With respect to the centrifuge screw, the above-mentioned object is achieved by the subject matter of claim 14. With respect to the solid bowl screw centrifuge, the above-mentioned object is achieved by the subject matter of claim 15. The subclaims comprise at least expedient embodiments and further developments.

[0012] Specifically, the problem is solved by a screw hub for a centrifuge screw, which comprises at least one monolithically formed hub section, in particular at least two interconnected monolithically formed hub sections. The screw hub extends along a longitudinal axis. This longitudinal axis also forms the longitudinal axis of the centrifuge screw or solid bowl screw centrifuge.

[0013] The at least one hub section has a peripheral wall and two end faces. A plurality of openings are formed in the peripheral wall, wherein the hub section, in particular the at least one hub section, has at least one transverse disk.

[0014] The screw hub according to the invention combines several advantages due to the novel design of at least one, preferably at least two, interconnected hub sections. Due to the monolithic design, the hub section exhibits particularly high rigidity. At the same time, a large penetration depth can be achieved due to the large number of openings. Since at least one cross disc is part of the monolithically formed hub section, this simplifies the production of the hub section, as the cross disc does not have to be connected to the hub in a separate process, but is already part of the screw hub.

[0015] A monolithically formed hub section is understood to mean, in particular, a hub section that is formed in one piece and without joints.

[0016] The longitudinal direction of a screw hub is essentially defined by the orientation of the screw hub's longitudinal axis. The longitudinal axis of a screw hub is the axis around which the screw hub rotates during use.

[0017] The longitudinal direction is preferably defined as the direction of transport of the solid discharge.

[0018] The centrifuge screw can have at least two different sections in its longitudinal direction. A first section is the cylindrical longitudinal section. A further section, following in the longitudinal direction, is the solids discharge section. This solids discharge section can, for example, be conical or double-conical, or tubular with a smaller diameter than the cylindrical longitudinal section.

[0019] The medium to be processed or separated using the centrifuge screw can be a multiphase medium. The medium can be, for example, a two-phase mixture or a three-phase mixture. It is also possible to use the screw hub according to the invention for a centrifuge screw for separating a three-phase mixture, with one solid phase and two liquid phases.

[0020] The monolithically formed hub section is preferably one of several hub sections of a screw hub. In other words, the screw hub is preferably formed from several, i.e. from at least two interconnected hub sections. In a particularly preferred embodiment of the invention, the screw hub is formed by at least two monolithically formed hub sections, wherein both monolithically formed hub sections have the features according to the invention, i.e. that both hub sections preferably have a peripheral wall and at least two end faces and a plurality of openings are formed in the peripheral wall and furthermore each hub section has at least one transverse disk.

[0021] It is possible for the at least two monolithically formed hub sections to be designed differently with regard to their inventive features. This means that although the at least two monolithically formed hub sections each have a transverse disk, these disks are arranged at different positions relative to the longitudinal extent of the respective hub section. Furthermore, the at least two monolithically formed hub sections can differ from one another with regard to their openings (e.g., arrangement, number, shape).

[0022] In other words, it is possible for a worm hub to be assembled or manufactured from several similarly formed hub sections. To achieve this, the similar, monolithically formed hub sections are joined together.

[0023] The hub sections can be connected to each other, in particular, by a material bond and / or force fit. A welded joint is particularly suitable for a material bond. This allows for a stable connection between the hub sections. It is also a comparatively simple method for connecting the hub sections, and the corresponding welding process can also be carried out automatically.

[0024] With the force-locking connection of the hub sections, especially with a screw connection, a hub section can be easily and quickly removed and replaced, for example due to wear. Furthermore, this type of connection of the hub sections enables a simple, modular design of the worm hub, making it easy to manufacture the worm hub in different sizes and lengths.

[0025] In a particularly preferred embodiment of the invention, the plurality of openings in the peripheral wall are formed as part of the monolithic shape of the hub portion. This means that the openings are not subsequently introduced into a peripheral wall, but rather the monolithic shape of the hub portion already includes these openings. In other words, the monolithically formed hub portion is designed such that, due to the manufacturing process, the monolithically formed hub portion already has its final shape. Thus, no further shape-forming post-processing steps, such as milling operations, are necessary.

[0026] The openings in the peripheral wall can have different shapes or geometries. For example, it is possible for the openings to be essentially triangular and / or rectangular. In particular, it is possible for the openings in a hub section to vary in both size and shape, i.e., to be designed differently. This enables the formation of a peripheral wall with an optimal distribution of the openings, particularly with regard to providing a web-like, in particular spiral-shaped, wall section that serves to secure a screw flight.

[0027] The openings in the peripheral wall can be defined by strut-like and / or web-like elements. In other words, the geometry or shape of the openings can be formed using strut-like and / or web-like elements.

[0028] At least in sections, the web-like elements can be the web-like wall section or a partial section of the web-like wall section that serves to secure a screw flight. Preferably, each opening is formed from at least one partial section of a web-like wall section and at least two struts, wherein the struts are preferably defined as wall sections that serve only to delimit the opening and do not form or have an additional wall section for securing a screw flight.

[0029] Furthermore, it is possible for an opening to be formed from two sections of one or more web-like wall sections and at least two struts.

[0030] In a preferred embodiment of the invention, the openings have a triangular shape, with two triangular openings being arranged relative to one another in such a way that the two openings form a diamond shape. In a particularly preferred embodiment of the invention, the hub section has a plurality of openings with a triangular shape, with two such openings together forming a diamond shape. The diamonds are in turn arranged offset from one another in the hub section. In a particularly preferred embodiment of the invention, a web-like wall section (which serves to attach a screw flight) in this case runs through the nodes of the struts. Such a design of the hub section enables a particularly stable and at the same time lightweight construction of the hub section.

[0031] The length of the monolithically formed hub section is preferably 0.5 to 3 times, in particular 1 to 2.5 times, in particular 1 to 2 times, the diameter of the hub section. Such length / diameter ratios can provide a monolithically formed hub section, which allows a screw hub to be formed from several, preferably identical or similar, monolithically formed hub sections.

[0032] In one possible embodiment of the invention, the at least one transverse disc is formed on an end face of the hub section. The end face of the hub section is one of the two end faces of the hub section that terminate the peripheral wall in the longitudinal direction of the hub section.

[0033] The design of a cross disk on only one end face of the hub section has the advantage of saving material in terms of the cross disks. By connecting multiple hub sections, a cross disk can be formed between each of the two hub sections to be connected.

[0034] In a further embodiment of the invention, it is possible for a transverse disk to be formed on each of the two end faces of the hub section. This, in turn, has the advantage that the hub sections formed in this way can be formed at any position of the screw hub to be formed. This means that the hub section formed monolithically in this way can also form the end part of a cylindrical longitudinal section of a screw hub. This applies both to a discharge-side end part of a cylindrical longitudinal section of a screw hub and to an inlet-side end part of a cylindrical longitudinal section of a screw hub.

[0035] When forming a hub section with two cross discs, it is possible to form the respective cross discs with a relatively thin material thickness, since when two such monolithically formed hub sections are connected, a common cross disc with a correspondingly greater material thickness can be formed due to a preferential abutment of at least two cross discs.

[0036] In a further embodiment of the invention, the at least one transverse disk of at least one monolithically formed hub section can be formed in the longitudinal direction of the hub section at a position that essentially corresponds to the bisector of the length of the hub section. A position that essentially corresponds to the bisector of the length of the hub section is to be understood in particular as a position that is formed centrally with respect to the length of the hub section. For manufacturing reasons alone, this does not have to correspond 100% exactly to the bisector of the length. Minor deviations, in particular deviations of ± 10%, in particular of ± 5%, are possible here.

[0037] When forming a plurality of such hub sections, which have at least one transverse disk at a position that essentially corresponds to the bisector of the length of the hub section, in particular the bisector of the length of the hub section, it is possible for the end faces of the hub section not to necessarily be formed in a plane that is perpendicular to the longitudinal axis of the hub section. Rather, it is possible for the end faces to be inclined or spiral-shaped or to overlap with an adjacent hub section. In such an embodiment of the invention, two monolithically formed hub sections to be connected can also be connected to one another by means of a connecting section, for example a weld seam, which does not correspond to a circumferential seam.

[0038] The shape of such a hub section with, for example, beveled ends corresponds to the shape of a circular cylinder cut at an angle. The bevel can be formed on both ends or front sides of the hub section. Formation on just one side is also possible, provided, for example, the relevant hub section is designed or positioned as the end section of the cylindrical longitudinal section of the worm hub.

[0039] It is possible for a plurality of monolithically shaped hub sections forming a worm hub with overlapping and / or oblique and / or spiral-shaped end faces to be arranged and designed complementarily to one another in such a way that they are designed to engage with one another, so that a connection of adjacent or adjacent hub sections can be realized which is particularly advantageous in terms of rigidity.

[0040] It is possible for a worm hub to be formed from several hub sections that are differently designed with regard to the cross-disk arrangement. For example, it is conceivable for the hub sections formed centrally with regard to the cylindrical longitudinal section to each be formed with two cross-disks, each formed on an end face of each individual hub section. Hub sections arranged at the ends, on the other hand, can be formed with just one cross-disk, for example. In this case, it is possible for the cross-disk to be formed only on one end face of the hub cutout or, for example, to be formed at a position that essentially corresponds to the bisector of the length of the hub section.

[0041] In the context of the present application, a monolithically formed hub section is not to be understood as a hub section that essentially consists of a tube into which a plurality of openings are subsequently introduced into the peripheral wall. Rather, the term "monolithic forming" refers to a hub section such that, based on an appropriately selected manufacturing process, the shape of the hub section, including the formation of the openings and the formation of at least one transverse disk, is formed in a single manufacturing process or manufacturing step.

[0042] The at least one cross disc is preferably annular. Forming a ring shape allows, for example, an inlet pipe of a solid bowl screw centrifuge to be guided through such a cross disc. Furthermore, a ring shape can allow liquid to flow through a central opening in the cross disc. The annular cross disc preferably has a circular width that corresponds at most to half the radius of the outer circle of the cross disc.

[0043] In a further embodiment of the invention, it is possible for the cross disc to have at least one opening formed in the center of the cross disc. This opening can be circular, for example. It is also possible for the opening to be elliptical or flower-shaped. Preferably, the opening of the cross disc is shaped such that an inlet pipe of a solid-bowl screw centrifuge can be passed through the opening.

[0044] In a further embodiment of the invention, it is possible for the cross plate of at least one hub section to have a plurality of openings formed along its outer circumference. In this case, the openings are formed such that the preferably circular outer peripheral edge is pierced by a plurality of openings. The openings are preferably evenly distributed in the circumferential direction of the cross plate. This allows, for example, the passage of fluid. The introduction of additional struts or reinforcing bars is also conceivable in this case.

[0045] In a further embodiment of the invention, the at least one transverse disc can have a plurality of openings distributed in the circumferential direction. The openings are preferably evenly distributed in the circumferential direction of the transverse disc. In other words, for example, the annular shape of a transverse disc can have a plurality of evenly distributed openings. Such openings allow the passage of liquids. The openings distributed in the circumferential direction can, for example, be circular, square, or triangular. The actual shape of the openings can be selected depending on the flow rates to be achieved. It is possible for the at least one transverse disc to have several of the aforementioned features and / or designs.

[0046] Due to a specially selected manufacturing process, the cross plate can have a variable thickness in its monolithic structure. It is therefore possible to form individual sections of the cross plate with a higher material thickness or greater thickness, so that the cross plate forms reinforcing sections at these points. In particular, such points with a higher thickness of the cross plate can be designed as a type of reinforcing strut. The thickness of the cross plate can, for example, decrease from radially outside to radially inside. Furthermore, it is possible for the sections of the cross plate which have a greater thickness or material thickness than the remaining sections of the cross plate to be arranged radially outwards from an (imaginary) center point of the cross plate.

[0047] The openings formed in the circumferential wall can be arranged spirally in the circumferential direction such that, preferably between longitudinally adjacent openings, at least one web-like wall section is formed which runs spirally in the circumferential direction and forms at least one 120° turn, in particular a 180° turn or a 360° turn, over the entire length of the hub section. The at least one web-like wall section, which runs spirally in the circumferential direction, serves in particular as a fastening surface for a screw flight to be fastened to the screw hub. The formation of a web-like wall section which runs spirally in the circumferential direction has the advantage that the screw flight can be easily connected to the screw hub in an automated process, in particular in an automated welding process.

[0048] Due to the preferred design of such a spirally extending wall section, which forms at least one 120° turn, in particular a 180° turn or a 360° turn, several monolithically formed hub sections can be combined and connected to one another in a simple manner, so that a screw helix winds preferably with a constant pitch around the screw hub formed from several hub sections.

[0049] The spiral arrangement of the openings in the circumferential wall is preferably understood to mean that the openings as a whole form a spiral shape. This is possible, for example, by different opening geometries and / or opening sizes and / or an offset arrangement of the openings in the longitudinal and / or circumferential direction of the hub section.

[0050] The spiral arrangement of the openings is preferably designed such that the openings and / or the struts or strut-like elements delimiting the openings are positioned such that when at least two hub sections are connected, the opening or strut structure is also formed continuously.

[0051] When connecting multiple hub sections, it is particularly preferred that both the web-like wall section and the opening or strut structure run continuously or with the same pitch. A screw hub formed in this way achieves a particularly good clarification effect.

[0052] In a further embodiment of the invention, the monolithically formed hub section has a plurality of webs defining the openings in the circumferential wall, wherein the webs, in particular the webs and the at least one web-like wall section, each extend in the longitudinal direction and transversely to the longitudinal direction of the screw hub. Such a web arrangement enables a spiral arrangement of the openings in the circumferential direction in a structurally simple manner.

[0053] In a further embodiment of the invention, such a number of openings is formed in the peripheral wall and / or the openings of the peripheral wall have such an opening cross-section that the peripheral wall is formed as an open wall structure.

[0054] An open wall structure is understood to mean, in particular, a wall structure that has a large number of openings and / or a large overall opening area in the relevant hub section. The opening area is understood to mean, in particular, the sum of all individual opening areas of individual openings in the relevant hub section. In other words, the opening area does not have to be a single, continuous opening area.

[0055] Preferably, the value of the opening area is larger than the value of the closed area. The closed area is understood to be the portion of the wall structure that is closed and does not allow material to pass from the inside of the screw hub to the outside (or vice versa). Furthermore, the closed area is preferably understood to be the sum of all individual closed areas in the peripheral wall of the hub section.

[0056] Furthermore and / or additionally, an open wall structure is understood to mean a wall structure of the hub section that has a high proportion of openings in the circumferential direction. The proportion of openings is preferably higher than the proportion of closed surfaces. The proportion of openings in the circumferential direction of the screw hub is preferably at least 50%, more preferably at least 60%, particularly preferably at least 65%, and further particularly preferably at least 80% of the entire wall structure in the circumferential direction.

[0057] Particularly preferably, the described proportion of openings is formed in the circumferential direction over the entire longitudinal extent of the open wall structure. For the purposes of the invention, a longitudinal extent is understood to mean an extension of a component, a section, etc., that runs essentially in the direction, preferably parallel, to the longitudinal axis of the screw hub and / or the centrifuge screw.

[0058] In a particularly preferred embodiment of the invention, the cylindrical longitudinal section of the screw hub is completely formed with an open wall structure according to previous definitions.

[0059] The formation of an open wall structure contributes to the formation of a large pond depth in a solid bowl screw centrifuge.

[0060] In a particularly preferred embodiment of the invention, the at least one monolithically formed hub section is designed as a cast body. In other words, the monolithically formed hub section is manufactured using a casting process. Standard cast materials can be used here. A casting process generally allows extremely complex designs to be produced with regard to a hub section. Compared to manufacturing processes that rely on the subsequent milling of openings or the welding together of several rod elements or components, the production of a hub section using a casting process is simpler and more cost-effective.

[0061] When using a casting process, the at least one hub section is preferably formed from a chromium-nickel steel and / or a duplex steel and / or a nickel-based steel.

[0062] In a particularly preferred embodiment of the invention, the at least one monolithically shaped hub section can be produced by a lost wax casting process.

[0063] Within the framework of a casting process, in particular a lost-wax casting process, it is possible to produce individual sections of the at least one monolithically formed hub section in different casting quality levels. Thus, the casting quality levels to be achieved for individual sections can be selected depending on the subsequent component loading and / or acting material stresses.

[0064] Furthermore, it is possible to produce or form individual sections of the at least one monolithically formed hub section with different wall thicknesses using a casting process, in particular a lost-wax casting process. In other words, individual sections of the at least one monolithically formed hub section can have different wall thicknesses. The wall thicknesses can be selected depending on the subsequent component loading and / or acting material stresses.

[0065] It is possible to form a variety of hub sections using a mold.

[0066] In a further embodiment of the invention, the at least one monolithically shaped hub section can be manufactured using a 3D printing process. Manufacturing using a 3D printing process also enables the construction of complex shapes or structures of a hub section. Thanks to a 3D printing process, all sections and subregions of the hub section can be manufactured using a single manufacturing step, without the need for rework, such as the subsequent creation of openings using a milling process.

[0067] When using a 3D printing process, the at least one hub section is preferably formed from a chromium-nickel steel and / or a duplex steel and / or a nickel-based steel.

[0068] A 3D printing process can, for example, be carried out through a shaping additive material deposition. The shaping additive material deposition can, for example, be carried out using a shielding gas welding device. The shielding gas welding device is preferably operated with a welding gas selected from one of the subgroups of main groups I, M1, M2, or N of the DIN EN ISO 14175 standard.

[0069] Welding is preferably performed using an active, reactive welding gas or an inert welding gas. This type of welding process can also be referred to as MAG or MIG welding, or as welding with active gas or inert gas. Such welding processes are collectively referred to as gas metal arc welding (GMAW).

[0070] Main Group I includes welding gases with 100 volume percent nominal argon (Subgroup 1), 100 volume percent nominal helium (Subgroup 2), and 0.5 to 95 volume percent nominal helium, with the remainder argon (Subgroup 3). These welding gases are completely inert.

[0071] Main group M1, subgroup 1 includes welding gases with 0.5 to 5.0 volume percent nominal carbon dioxide, 0.5 to 5.0 volume percent nominal hydrogen, and the balance argon or helium. These welding gases are slightly oxidizing and only slightly reducing. Main group M1, subgroup 2 includes welding gases with 0.5 to 5.0 volume percent nominal carbon dioxide, and the balance argon or helium. These welding gases are slightly oxidizing. Main group M1, subgroup 3 includes welding gases with 0.5 to 3.0 volume percent nominal oxygen, and the balance argon or helium. These welding gases are also slightly oxidizing. Main group M1, subgroup 4 includes welding gases with 0.5 to 5.0 volume percent nominal carbon dioxide, 0.5 to 3.0 volume percent nominal oxygen, and the balance argon or helium. These welding gases are also slightly oxidizing.

[0072] Main group M2, subgroup 0 includes welding gases with 5.0 to 15.0 volume percent nominal carbon dioxide and the remainder argon or helium. These welding gases have low oxidizing power. Main group M2, subgroup 1 includes welding gases with 15.0 to 25.0 volume percent nominal carbon dioxide and the remainder argon or helium. These welding gases also have low oxidizing power. Main group M2, subgroup 2 includes welding gases with 3.0 to 10.0 volume percent nominal oxygen and the remainder argon or helium. These welding gases also have low oxidizing power. Main group M2, subgroup 3 includes welding gases with 0.5 to 5.0 volume percent nominal carbon dioxide, 3.0 to 10.0 volume percent nominal oxygen and the remainder argon or helium. The main group M2, subgroup 4 includes welding gases with 5.0 to 15.0 volume percent nominal carbon dioxide, 0.5 to 3.0 volume percent nominal oxygen and the remainder argon or helium.Main group M2, subgroup 5 includes welding gases with 5.0 to 15.0 volume percent nominal carbon dioxide, 3.0 to 10.0 volume percent nominal oxygen, and the balance argon or helium. Main group M2, subgroup 6 includes welding gases with 15.0 to 25.0 volume percent nominal carbon dioxide, 0.5 to 3.0 volume percent nominal oxygen, and the balance argon or helium. Main group M2, subgroup 7 includes welding gases with 15.0 to 25.0 volume percent nominal carbon dioxide, 3.0 to 10.0 volume percent nominal oxygen, and the balance argon or helium. These welding gases are also comparatively low in oxidation.

[0073] Main group N, subgroup 1 includes welding gases with 100 volume percent nominal nitrogen. Main group N, subgroup 2 includes welding gases with 0.5 to 5.0 volume percent nominal nitrogen and the balance argon or helium. Main group N, subgroup 3 includes welding gases with 5.0 to 50.0 volume percent nominal nitrogen and the balance argon or helium. Main group N, subgroup 4 includes welding gases with 0.5 to 1.0 volume percent nominal hydrogen, 0.5 to 5.0 volume percent nominal nitrogen and the balance argon or helium. Main group N, subgroup 5 includes welding gases with 0.5 to 50.0 volume percent nominal hydrogen and the balance nitrogen. All of these welding gases are inert. They are inert with high argon or helium content and they are only slightly reducing even with increasing hydrogen content.

[0074] In summary, welding gases that are inert, have low oxidizing and / or low reducing properties are preferably selected. With such a process, a low-oxidation weld bead and largely no slag can be produced during formative buildup welding or formative additive material deposition. This is particularly advantageous for overlapping weld beads. Furthermore, a particularly fast welding speed can be achieved. This initially enables particularly short production times. The real advantage of a fast welding speed, however, is that the at least one monolithically formed hub section is only slightly heated at specific points during welding, thus resulting in minimal distortion or deformation.

[0075] A major advantage of the described procedure is that such build-up welding results in a particularly high wear resistance of the surface produced.

[0076] For example, according to this embodiment, subsequent treatment, in particular the application of wear layers, can be dispensed with.

[0077] For example, the welding gas has a nominal carbon dioxide content of less than 20 percent by volume. Such a low carbon dioxide content makes it possible, in particular, to process structural steels using pulse welding. At the same time, a comparatively high burn-off of the welding wire is possible. This results in high mass build-up during welding and particularly fast processing. Furthermore, welding gas with a nominal oxygen content of less than 3 percent by volume is preferably used as the welding gas. Such welding gases are particularly low in oxidation. Welding gases with a high argon content are also particularly inexpensive.

[0078] In one embodiment of the invention, a gas-shielded welding device is operated with a pulsed arc. Such a pulsed arc allows precise control of the melting of the welding wire on the gas-shielded welding device. Furthermore, the heat input into the at least one monolithically shaped hub section can be deliberately kept particularly low. This makes it possible to minimize temperature-related deformations. The electrical welding current of such a pulsed arc welding device has, for example, a base current of less than 200 amperes and a pulsed current of greater than 200 amperes. Such welding currents are advantageous for particularly precise material build-up with comparatively low heat input. The welding gas used is advantageously a welding gas with 98 volume percent nominal argon and 2 volume percent nominal carbon dioxide.

[0079] It is also particularly advantageous to operate a gas-shielded welding system with a short arc, especially a reduced-energy short arc. This type of process with a short arc is also known as a cold arc, a process with a particularly cold arc. To achieve a still highly molten arc, it is particularly advantageous to use an increased melting current pulse.

[0080] A shielding gas welding device is particularly advantageously operated with one welding wire, or advantageously two welding wires (twin welding process) with a diameter of 0.5 mm to 3.0 mm, preferably from 1.0 mm to 1.6 mm.

[0081] Such a welding wire diameter enables high welding speeds and, at the same time, particularly low thermally induced deformation. Individual welding layers or welding passes with a width of 6 to 7 mm are particularly preferred. If a contour is to be produced using the method according to the invention, a welding layer or welding pass has a width of at least 2 mm.

[0082] The at least one hub section to be monolithically formed can preferably be moved during manufacturing. During this movement, the at least one hub section to be monolithically formed is aligned at its welding point in such a way that an optimal position is achieved for the applied welding layer. The welding layer is particularly preferably applied to a horizontal surface.

[0083] It is also advantageous if the weld layer is applied to a surface that slopes slightly in the welding direction. The slope angle is preferably between 5° and 15°, advantageously between 7° and 10°. The at least one hub section to be formed monolithically is preferably moved accordingly such that a horizontal welding surface or a welding surface that slopes upwards in the welding direction of the inert gas welding device is present at the welding location of the inert gas welding device.

[0084] The screw hub can have several, in particular two or three or four or five, hub sections that are connected to one another. The connected hub sections form a longitudinal section of the screw hub, preferably the entire longitudinal section of the screw hub. Thus, the cylindrical longitudinal section of a screw hub can be formed from several, preferably similar or identical hub sections. This enables simple modular assembly or joining of the screw hub from any number of hub sections.

[0085] The hub sections can be connected to one another in a material-to-material and / or force-fitting manner. A welded connection is particularly suitable for a material-to-material connection. On the one hand, this enables a stable connection between the hub sections. On the other hand, it is a comparatively simple method for connecting the hub sections, and the corresponding welding process can also be carried out automatically. With a force-fitting connection of the hub sections, in particular by screwing, a hub section can be easily and quickly removed and replaced, for example due to wear. Furthermore, this type of connection of the hub sections enables a modular design of the worm hub, so that the worm hub can be easily manufactured in different sizes and lengths.

[0086] The hub sections are preferably connected to one another in such a way that web-like wall sections of the respective hub sections, in particular web-like wall sections according to dependent claim 6, are positioned relative to one another in such a way that a continuously spirally extending fastening section for fastening a screw flight is formed over the entire longitudinal section of the screw hub. This enables the secure and automated fastening of a screw flight to the screw hub. In a further embodiment of the invention, several web-like wall sections can be formed in the peripheral wall. This enables the formation of several fastening sections for fastening several screw flights.

[0087] With the aid of a worm hub formed according to the invention, it is advantageously possible to replace or repair individual hub sections of worm hubs if they are defective or show signs of wear. This also applies to hub sections of worm hubs that are not or were not initially designed according to the invention, wherein the worm hub comprises a hub section of a worm hub according to the invention after a repair has been carried out.

[0088] A further subordinate aspect of the invention relates to a centrifuge screw with a screw hub according to the invention and a screw helix arranged circumferentially on the screw hub. The screw helix is ​​preferably attached to spirally extending fastening sections of the screw hub. The at least one spirally extending fastening section is preferably formed by a web-like wall section of the peripheral wall.

[0089] It is possible for the centrifuge screw to have multiple screw flights, in particular two screw flights. In this case, at least two spaced-apart web-like wall sections are formed in the peripheral wall of the at least one hub section, preferably of the plurality of hub sections, to enable the two screw flights to be secured.

[0090] A further subordinate aspect of the invention relates to a solid bowl screw centrifuge comprising a centrifuge screw located in a drum, wherein the centrifuge screw is designed according to the invention and / or has a screw hub according to the invention.

[0091] With regard to the centrifuge screw and the solid bowl screw centrifuge, reference is made to the advantages explained in connection with the screw hub.

[0092] The invention is explained in more detail below with reference to the accompanying drawings.

[0093] The illustrated embodiments represent examples of how the screw hub according to the invention or the centrifuge screw according to the invention can be designed. In particular, the figures depict monolithically shaped hub sections that can form a screw hub according to the invention.

[0094] The figures show: Fig. 1 shows a longitudinal section through a centrifuge screw according to the invention; Figs. 2 - 4 show different embodiments with respect to a monolithically shaped hub section for forming a screw hub according to the invention.

[0095] In the following, the same reference numbers are used for identical and equivalent parts.

[0096] In Fig. 1 A centrifuge screw 10 according to the invention is shown with a screw hub 20 according to the invention. The screw hub 20 has a cylindrical longitudinal section 11, a conical section 12, and a bearing section 13 in the longitudinal direction R. The sections 11, 12, and 13 have the longitudinal axis L as a common axis.

[0097] In the present case, the conical section 12 corresponds to the solids side section, provided that the centrifuge screw shown is designed as part of a solid bowl screw centrifuge.

[0098] The bearing section 13 serves to accommodate a bearing, in particular a worm bearing, in order to rotatably support the worm hub 20.

[0099] In further embodiments of the invention, section 12 may have a shape other than a simple cone. For example, section 12 may be formed as a cylindrical section and a cylindrical tube section. Furthermore, section 12 may have a double truncated cone shape. The cylindrical longitudinal section 11 of the worm hub 20 is arranged in the longitudinal direction R between the conical section 12 and the bearing section 13. Sections 11, 12, and 13 are firmly connected to one another.

[0100] The worm hub 20 is surrounded radially on the outside by the worm helix 60. The worm hub 20 thus serves to support the worm helix 60 in the radial direction, to transmit torques from the drive to the worm helix 60, and in particular to absorb tensile and thrust forces.

[0101] The longitudinal direction R runs essentially parallel to the longitudinal axis L of the screw hub 20. In this case, the longitudinal direction R is defined as the direction of transport of the solids discharge. The solids transport takes place as shown in the Fig. 1 from right to left.

[0102] The cylindrical longitudinal section 11 is longer than the conical section or solids discharge side section 12. The section 12 of the screw hub 20 is to be understood as such a section which serves in particular for transporting the solids separated from the material to be processed in the direction R of the solids discharge.

[0103] In the example shown, the cylindrical longitudinal section 11 of the worm hub 20 is formed from four hub sections 30a, 30b, 30c, and 30d. The monolithically formed hub sections 30a, 30b, 30c, and 30d are connected to one another, in particular welded together. The two hub sections 30b and 30c can be referred to as middle hub sections. These are located between the end hub sections 30a and 30d. The end hub section 30a thus forms the end part or end section of the cylindrical longitudinal section 11 facing the conical section 12. The end hub section 30d, on the other hand, forms the end part or end section of the cylindrical longitudinal section 11 facing the bearing section 13 or the end of the worm hub 20 opposite the conical section 12.

[0104] The hub sections 30a - 30d each have a circumferential wall 31 in which a plurality of openings 32 are formed. Furthermore, each hub section 30a - 30d each has a transverse disc 40. The transverse disc 40 is formed on one end face, namely on the second end face 34 of the respective hub section 30a - 30d. The individual hub section 30a - 30d each has two end faces, namely a first end face 33 and a second end face 34. The end faces 33 and 34 limit the longitudinal extent of the circumferential wall in the longitudinal direction R. The first end face 33 is the first end face of the respective hub section 30a - 30d in the longitudinal direction R. The second end face 34 forms the second end face of the respective hub section 30a - 30d in the longitudinal direction R.The hub sections 30a - 30d are connected to one another in such a way that the second end face 34 of a hub section is connected to the first end face 33 of the hub section 30a - 30d of the adjacent or adjacent hub section.

[0105] The cross disc 40 is thus located in the connection area between two hub sections.

[0106] The length LN of the respective hub section 30a - 30d is preferably 1 to 2 times the diameter D of the hub section 30a - 30d. In the present case, the hub sections 30a - 30d are all of the same design. This also applies to the length LN of the hub section and its relationship to the respective diameter D of the hub section. In the illustrated longitudinal section of the worm hub 20, it can be seen that at least one web-like wall section 35 is formed in the peripheral wall 31, which runs in a spiral shape. This web-like wall section 35 forms a support surface for the worm flight 60 on the outward-facing surface 36. The worm flight 60 can be connected to the worm hub 20 at this support surface.

[0107] The web-like wall section 35 extends over the entire length LN of the hub section 30 such that at least a 120° rotation is formed. In the example shown, a rotation of more than 360° is formed. Since the hub sections 30a-30d are of identical design, the hub sections 30a-30d can be positioned and fastened to one another such that the individual web-like wall sections 35 form a web-like wall section that runs continuously with respect to the cylindrical longitudinal section 11 of the screw hub 20. This continuous web-like wall section of the cylindrical longitudinal section 11 preferably has a constant pitch over the entire length of the cylindrical longitudinal section 11.

[0108] In the present case, the openings 32 of the hub sections 30a-30d each have a triangular shape. The example of the end hub section 30d shows that this triangular shape is formed by two struts or strut-like elements 37 and a partial section of the web-like wall section 35. The two openings 32' are positioned relative to one another such that together they form a diamond shape. Several diamonds are in turn arranged offset from one another in the hub section 30d. The web-like wall section 35 (which serves to attach a screw flight) runs through the nodes 38 of the struts 37 in this exemplary embodiment. Such a design of the hub section 30d enables a particularly stable and, at the same time, lightweight construction of the hub section 30d. In the example shown, all hub sections 30a-30d have the same basic construction.

[0109] In Fig. 2 a single monolithically formed hub section 30 is shown, as shown in Fig. 1 can form a cylindrical longitudinal section 11 of the worm hub 20. The perspective view shows in particular the design of the transverse disc 40. The transverse disc 40 is essentially annular.

[0110] The ring surface is formed between an inner circular edge 42 and an outer circular edge 43.

[0111] The opening 41 is formed at the center M of the transverse disc 40. The diameter of the opening 41 is formed by the inner circle edge 42.

[0112] The circular ring width KB is preferably at most 50% of the radius r of the transverse disc 40.

[0113] The opening 41 of the cross plate 40 serves, on the one hand, for the passage of an inlet pipe. This is particularly necessary when forming the hub section 30, if, for example, it is arranged at the positions of the screw hub 20 to form a hub section 30c or 30d (see Fig. 1 ). Furthermore, the opening 41 serves to allow the passage of liquid.

[0114] Additional openings 44 are formed in the circular ring of the cross disc. These are evenly distributed in the radial direction of the cross disc 40. These openings 44 also serve as passages for fluids.

[0115] It has been shown that a circular ring width KB with the specified maximum dimension provides sufficient stability on the one hand and, on the other hand, creates the largest possible passage for liquids.

[0116] The circumferential wall 31 of the hub section 30 is formed with an open wall structure. This means that the circumferential wall 31 in the present case has such a number of openings 32 and such an opening cross-section of the openings 32 that the circumferential wall 31 as a whole can be described as an open wall structure. The openings 32 in the present case have a substantially triangular shape. The triangular shapes of the openings 32 are offset and arranged alternately with one another in such a way that a web-like wall section 35 is formed between the openings 32, which extends spirally in the circumferential direction.

[0117] The outward-facing surface 36 of the web-like wall section 35 can be seen. A screw flight 60 (not shown) can be attached to this outward-facing surface 36. The openings 32 are formed by struts 37 and partial sections of the web-like wall section 35 to form the triangular opening cross-sections in this case, wherein the struts 37 and the web-like wall section 35 each extend in the longitudinal direction R and transversely to the longitudinal direction R of the screw hub 20. Such a shape of a hub section 30, wherein the openings 32 are offset from one another and arranged alternately in terms of shape, can be produced in particular by means of a casting process.

[0118] In Fig. 3 An alternative embodiment is shown with respect to a hub section 30. This hub section 30 also has a transverse disc 40 on one end face, wherein this transverse disc 40 also has a circular ring shape.

[0119] The hub portion 30 differs from the hub portion 30 according to the embodiment of the Fig. 2 in particular by the shape of the openings 32 formed in the peripheral wall 31. The openings 32 are designed in terms of size and shape such that a spirally extending, web-like wall section 35 with an outward-facing surface 36 is formed. The openings 32 have different longitudinal extensions in the longitudinal direction R to form the spirally extending, web-like wall section 35. Furthermore, the shapes of the openings 32 differ from one another. The openings 32a essentially have a quadrangular basic structure. The openings 32b, on the other hand, have a triangular shape. As a result, the sections of the peripheral wall 31 formed between the end faces 33 and 34 and the web-like wall section 35 are formed with the largest possible openings 32, while at the same time enabling a spiral extension of the web-like wall section 35.

[0120] In Fig. 4 A further embodiment is shown with regard to a hub section 30. This again has a transverse disk 40 on an end face 33. The openings 32 have, as already described in connection with the embodiment according to Fig. 3 As explained, different opening shapes are present. In addition to triangular openings 32b, essentially square openings 32a are formed.

[0121] The hub section 30 has two web-like wall sections 35a and 35b. The web-like wall sections 35a and 35b extend spirally and are spaced apart from one another. Due to the formation of two web-like wall sections 35a and 35b, several spaced-apart screw flights 60 can be attached to a screw hub. The web-like wall sections 35a and 35b both extend over the entire length LN of the hub section 30 and each form a twist of at least 120°.

[0122] By connecting several hub sections 30, as shown in Fig. 3 As shown, a screw hub 20, in particular a cylindrical longitudinal section 11 of a screw hub 20 can be formed, which has several, in particular two, screw flights.

[0123] Due to the large number and size of the openings 32a and 32b formed, an open wall structure is formed. The openings 32a and 32b are formed by struts 37 and sections of the web-like wall sections 35a and 35b. List of reference symbols

[0124] 10 Centrifuge screw 11 Cylindrical longitudinal section 12 Conical section 13 Bearing section 20 Screw hub 30, 30a, 30b, 30c, 30d Hub section 31 Circumferential wall 32, 32', 32a, 32b Opening in circumferential wall 33 First end face 34 Second end face 35, 35a, 35 Web-like wall section 36 Outward-facing surface 37 Strut 38 Node 40 Cross disc 41 Opening in cross disc 42 Inner circle edge 43 Outer circle edge 44 Distributed openings 60 Screw flight LLongitudinal axis LN Length of hub section D Diameter of hub section RLongitudinal direction r Radius of cross disc M Center of cross disc KB Width of circular ring

Claims

1. A screw hub (20) for a centrifuge screw (10), comprising at least one monolithically formed hub section (30), in particular at least two monolithically formed hub sections (30), which are connected to one another, wherein the at least one hub section (30) has a circumferential wall (31) and two front sides (33, 34) and a plurality of openings (32) is formed in the circumferential wall (31), characterized in that the hub section (30) has at least one transverse disk (40).

2. The screw hub (20) according to claim 1, characterized in that the length (LN) of the hub section (30) is 0.5 to 3 times, in particular 0.75 to 2.5 times, in particular 1 to 2 times, the diameter (D) of the hub section (30).

3. The screw hub (20) according to claim 1 or 2, characterized in that the at least one transverse disk (40) is formed on a front side (33, 34) of the hub section (30).

4. The screw hub (20) according to one of claims 1 to 2, characterized in that in the longitudinal direction (R) of the hub section (30), the at least one transverse disk (40) is formed at a position, which corresponds essentially to the length bisector of the length (LN) of the hub section (30).

5. The screw hub (20) according to one of the preceding claims, characterized in that a transverse disk (40) is formed in a ring-shaped manner and / or has at least one opening (41) formed in the center point (M) of the transverse disk (40) and / or several openings formed on the outer circumference and / or several openings (44) arranged so as to be distributed in the circumferential direction.

6. The screw hub (20) according to one of the preceding claims, characterized in that at least one web-like wall section (35) is formed in the circumferential wall (32), which wall section runs spirally in the circumferential direction and forms at least a 120° degree rotation, in particular a 180° degree rotation or a 360° rotation across the entire length (LN) of the hub section.

7. The screw hub (20) according to claim 6, characterized in that the openings (32) formed in the circumferential wall (31) are arranged spirally in the circumferential direction in such a way that, preferably between openings (32) adjacent in the longitudinal direction (R), at least one web-like wall section (35) is formed, which runs spirally in the circumferential direction and which forms at least a 120° degree rotation, in particular a 180° degree rotation or a 360° rotation across the entire length (LN) of the hub section (30).

8. The screw hub (20) according to one of the preceding claims, in particular according to claim 6 or 7, characterized by several webs (37) delimiting the openings (32) of the circumferential wall (31), wherein the webs (37), in particular the webs (37) and the at least one web-like wall section (35), in each case extend in the longitudinal direction (R) and transversely to the longitudinal direction of the screw hub (20).

9. The screw hub (20) according to one of the preceding claims, characterized in that such a number of openings (32) is formed in the circumferential wall (31) and / or the openings (32) of the circumferential wall (31) have such an opening cross section that the circumferential wall (31) is formed as open wall structure, wherein such a wall structure is to be understood as an open wall structure, which has a higher proportion of openings than of closed surfaces in the circumferential direction.

10. The screw hub (20) according to one of the preceding claims, characterized in that the at least one hub section (30) is formed as cast body.

11. The screw hub (20) according to one of claims 1 to 9, characterized in that the at least one hub section (30) is produced by means of a 3D printing process.

12. The screw hub (20) according to one of the preceding claims, characterized by several, in particular two or three or four or five, hub sections (30), which are connected to one another, in particular connected to one another by means of a substance-to-substance bond and / or in a non-positive manner, and form at least one longitudinal section (11) of the screw hub (20), preferably the complete longitudinal section (11) of the screw hub (20).

13. The screw hub (20) according to claim 12, characterized in that the hub sections (30) are connected to one another in such a way that web-like wall sections (35) of the hub sections (30), in particular web-like wall sections (35) according to claim 7, are positioned relative to one another in such a way that a continuously spirally running fastening section for fastening a screw flight (60) is formed across the complete longitudinal section (11) of the screw hub (20).

14. A centrifuge screw (10) with a screw hub (20) according to one of the preceding claims 1 to 13 and at least one screw flight (60), which is circumferentially arranged on the screw hub (20).

15. A solid bowl screw centrifuge with a centrifuge screw (10) according to claim 14 and / or a screw hub (20) according to one of claims 1 to 13.