Screw conveyor for a screw separator and manufacturing process for a screw conveyor

Description

[0001] The invention relates to a screw conveyor, in particular for a separator device for dewatering moist masses, and to a separator device for dewatering moist masses. Furthermore, the invention relates to a method for the additive manufacturing of a screw conveyor and to the use of a screw conveyor in a separator device.

[0002] Screw conveyors are used in various sectors to convey different goods, for example in screw conveyors or separator devices.

[0003] Separator devices with screw conveyors are used particularly for dewatering moist materials, such as liquid manure or digestate. One such separator device is known, for example, from DE 10 2006 052 669 A1. In this device, the screw conveyor rotates within a cylindrical screen, forcing the liquid portion of the material to be dewatered through the screen. For efficient filtration, a good seal between the screw conveyor and the cylindrical screen is desirable for sealing and screen cleaning. A cylindrical screen with the thinnest possible walls is advantageous to prevent clogging of the screen openings. However, screw separators of this design are subject to wear on the outer circumference of the screw flights and the cylindrical screen, which can lead to a reduction in throughput.

[0004] From DE 10 2006 002 016 A1, a separator device is known in which a screw conveyor has surface irregularities on its outer circumference. From DE 10 2008 048 091 A1, a separator device is known in which a clearing element comprises two rotor elements arranged parallel to each other, between whose outer edges a clamping gap is formed. Fibrous materials can become trapped in this clamping gap, creating a seal between the screw conveyor and a cylindrical screen surrounding the screw conveyor and clearing the openings of the cylindrical screen. While this can achieve improved clearing of the screen openings, a disadvantage of this separator device is the high friction that occurs between the fibrous materials trapped in the clamping gap and the inner wall of the cylindrical screen arranged around the rotor elements.This can lead to undesirably high wear of the cylinder sieve and furthermore require increased drive energy to overcome the friction.

[0005] DE 10 2017 103 068 A1 discloses a solid-jacketed screw centrifuge screw with a screw hub. The screw hub has a cylindrical longitudinal section, which is manufactured as a tube using a conventional method. The screw hub also has a frustoconical longitudinal section, which is manufactured by form-fitting welding.

[0006] The invention is therefore based on the objective of providing an improved solution that addresses at least one of the aforementioned problems. In particular, it is an objective of the invention to provide a solution that reduces the maintenance effort as well as the frictional energy losses occurring during operation of a separator device.

[0007] According to a first aspect, the aforementioned problem is solved by a screw conveyor according to claim 1, a method for manufacturing a screw conveyor according to claim 9 and a use of a screw conveyor according to claim 18.

[0008] Such fibrous materials can be formed, for example, from straw or silage contained in slurry when the separator device is used to separate slurry.

[0009] A separator device is understood to be, in particular, a screw press separator. The terms screw press separator and screw separator are preferably to be understood synonymously. Separator devices are used especially for dewatering moist materials, such as liquid manure or digestate. Separator devices are specifically designed for separating the solid and liquid components of moist materials. Liquid can be separated from the moist material by means of a sieve, thus significantly reducing the liquid content of the moist material.

[0010] The shaft is preferably not manufactured using a non-additive manufacturing process. It can, for example, be conventionally machined from a semi-finished product, which may be cast, forged, or extruded. The shaft is preferably designed as a hollow shaft. Preferably, the shaft has a connection point, preferably comprising a groove, designed to connect a drive shaft to the shaft in a rotationally fixed manner. The outer circumference of the shaft is preferably cylindrical or substantially cylindrical. In alternative embodiments, the outer circumference of the shaft can increase in the conveying direction, for example, to achieve compression. Likewise, in alternative embodiments, the outer surface of the screw flight(s) can be tapered in the conveying direction, and the screen can have a correspondingly congruent inner circumferential surface.

[0011] According to the invention, the shaft comprises or consists of metallic material, preferably steel, particularly stainless steel. The axis of rotation preferably runs in the axial direction. The shaft can be rotatably mounted in a separator device so that the shaft is rotatable about the axis of rotation.

[0012] The screw flight preferably extends around the shaft in a helical and / or screw-like manner, having a specific pitch, which may be constant or variable along the screw flight. "Helix-like" refers in particular to a helical and / or screw-like design. A variable pitch may be particularly preferred if an increasing compression of the conveyed mass and / or an increasing axial pressure on the conveyed mass is desired in the axial direction. Preferably, the screw flight extends axially along a partial axial section of the shaft or axially along the entire shaft. The screw flight is preferably bonded to the shaft circumferentially, particularly along its entire axial extent.

[0013] The outer edge of the screw flight refers in particular to the outer circumferential surface of the screw flight. The outer edge preferably runs along the radially outer circumference of the screw flight and has a width that is preferably constant.

[0014] Preferably, several recesses, designed as depressions, are arranged in the outer edge. The individual recesses can be, in particular, pocket-shaped and / or groove-shaped. It is preferred that the recesses are spaced apart from one another. Preferably, the recesses are substantially identical in design. Preferably, the distance between the recesses is substantially the same. The recesses are preferably designed to receive solids, especially fibrous solids. A recess can be designed as a groove or a depression.A recess can have a constant or decreasing width over its depth extension; however, in preferred embodiments, a recess has an undercut in such a way that the opening cross-section of the recess located at the outer edge is partially or entirely smaller than a recess cross-section located in the depth of the recess, so that fibrous materials can become trapped in the recess particularly effectively and permanently.

[0015] Fibrous materials can accumulate in the recesses, becoming trapped and being moved in a circular path by the screw conveyor during a rotational movement around its outer circumference. The fibrous materials in the recesses preferably form a brush-like surface on the outer circumference of the screw conveyor, which is in contact with and brushes over a sieve within the separator device, thus continuously cleaning the sieve. The fibrous materials present in the recesses preferably regenerate themselves continuously and automatically, ensuring thorough and lasting cleaning of the sieve.

[0016] The screw impeller is an additively manufactured metallic structure. Additive manufacturing refers to the point-by-point, layer-by-layer, or portion-by-portion construction of a component, in which a curable material is bonded to form the component through curing and bonding in a selective deposition process controlled by the product geometry data. Curing can occur, for example, through melting and subsequent solidification or through a cross-linking reaction. The point-by-point, layer-by-layer, or portion-by-portion manufacturing process can be observed in the component by examining corresponding structures in a micrograph or on untreated surfaces.

[0017] Additive manufacturing makes it possible, on the one hand, to create an outer edge on the screw flight that is sufficiently wide to accommodate recesses that achieve this fiber-trapping effect. On the other hand, additive manufacturing allows the recesses to be produced directly within the additive manufacturing process, thus enabling the creation of multiple recesses in a time-saving manner without the need for subsequent machining operations. In this way, the geometries of the screw conveyor made possible by additive manufacturing can be advantageously used to improve the functional structure of the screw conveyor.Advantageously, the improved geometry of the screw conveyor with recesses is produced by the proposed additive manufacturing process: However, the invention also encompasses a screw conveyor produced by additive manufacturing without such recesses; which is characterized by other geometric features; for example, the inwardly tapered cross-sectional profile of the screw wings explained below, or other further development features explained below.

[0018] The screw conveyor according to the invention can achieve an efficient and cost-effective manufacturing strategy by efficiently and precisely prefabricating the shaft in a conventional process and additively building up and manufacturing the screw wing in an individual and specific geometry on the shaft as a substrate element.

[0019] According to a first preferred embodiment, the screw flight has a cross-sectional profile with a width in the region of the outer circumference of the screw flight and a width in the region of the inner circumference of the screw flight, and the width in the region of the outer circumference of the screw flight is greater than the width in the region of the inner circumference of the screw flight. Here, the cross-sectional profile is understood to be a section through the screw flight, for example, in a plane perpendicular to the axis of rotation of the screw conveyor or perpendicular to the flank surface of the screw flight. The cross-sectional profile is preferably designed such that the width of the screw flight is smaller in the region of the inner circumference than in the region of the outer circumference of the screw flight. In particular, the cross-section is designed such that the screw flight widens, preferably continuously, in the radial direction from the radial inside to the radial outside.This means in particular that the worm's wing is wider in the area of ​​the outer circumference than in the area of ​​the inner circumference, or that the worm's wing has a narrower width in the area of ​​the inner circumference than in the area of ​​the outer circumference.

[0020] The snail wing preferably has a cross-sectional profile that widens radially outwards, preferably continuously.

[0021] It is particularly preferred if the cross-sectional profile of the screw flight has at least one section with constant width and at least one section with varying width, in particular increasing radially outwards. These sections can be adjacent to each other, especially in the radial direction.

[0022] According to a preferred embodiment, the cross-section is designed such that the screw flight has an inner section with constant width and / or a middle section with an outwardly increasing width and / or an outer section with constant width in the radial direction from radially inside to radially outside.

[0023] The screw blade is preferably designed such that less material is applied near the axis of rotation of the screw blade, or at smaller radii, than at larger radii. In the area near the axis of rotation, layer build-up can therefore be advantageously quick and thus cost-effective. In the area far from the axis of rotation, or at larger radii, a wider structure can be applied. Preferably, fiber pockets are arranged in the wide outer structure.

[0024] Such a screw conveyor can be advantageously used in a separator device, enabling low-maintenance, service-friendly dewatering, for example in the processing of slurry or digestate.

[0025] However, a screw conveyor described here can also be used in a screw conveyor or other device that is not used for dewatering moist masses.

[0026] One advantage of this type of screw conveyor is that, due to the multiple spaced recesses, there is no continuous opening. This reduces friction losses that occur between the solids in the recesses and a screening device arranged around the screw conveyor in a separator system. This reduces wear on the screening device, thus extending the service life of the components and reducing maintenance frequency. Furthermore, the reduced friction losses mean less drive energy is required to power the screw conveyor, thereby lowering the overall energy consumption of the separator system.

[0027] Another advantage of such a screw conveyor is that significant material savings can be achieved through the radially widening cross-section of the screw flight. This means less material is required for the screw flight, thus reducing the material costs for the screw conveyor.

[0028] Furthermore, the reduced material usage allows the screw conveyor to have a lower weight compared to conventional screw conveyors, which can particularly facilitate maintenance procedures.

[0029] Typically, during operation of a screw conveyor, the outer circumference of the screw flights is subjected to high mechanical stress, and the outer edge of the screw is usually the area most affected by wear. Due to the screw flight design, in which the outer circumference is wider than the inner circumference, the wear caused by the increased material thickness on the outer edge is compensated for. This allows for a longer axial but wider radial gap to the inner wall of the screw or screen tube, resulting in a lower surface load between the outer edge of the screw flight and the screen, thus reducing wear on both sides. Consequently, the screw conveyor and the screw or screen tube exhibit a significantly extended service life.

[0030] According to a particularly preferred embodiment, the screw blade is a structure produced by wire-based additive manufacturing using arc welding, in particular by metal inert gas welding (MIG), preferably by metal inert gas welding (MIG) and / or metal active gas welding (MAG).

[0031] The screw blade then exhibits, in particular, the structure typical of wire-based additive manufacturing using arc welding. Preferably, the screw blade is produced by arc wire deposition welding. The "Wire Arc Additive Manufacturing (WAAM)" process is particularly preferred, which is a type of 3D printing for metal structures using welding processes. It is preferred that arc welding is used for the layer-by-layer construction of the component, whereby a metal wire is fused at the correct location using a welding torch to form the desired blank. At a minimum, a three-axis movement is required for the production of complex structures, in order to rotate the component and move the welding head in the axial and radial directions.A rotating build platform, combined with swivel axes of the build platform or the welding head, allows for material build-up in 5- to 8-axis configurations. This enables the production of complex structures with cavities, particularly in the form of recesses. A component built in this way can then be further processed, for example, by CNC milling to meet specific surface requirements.

[0032] Arc welding is a welding process in which an electric arc (welding arc) burns between the workpiece and an electrode that can melt and then simultaneously serves as filler material.

[0033] Gas metal arc welding (GMAW) is a welding process that uses shielding gases flowing around the electrode and the molten metal. The supply of these shielding gases can be integrated into the torch. In gas metal arc welding (GMAW), an electrode made of the same or a similar material as the workpiece can be melted. Metal inert gas welding (MIG) is a form of gas metal arc welding that uses inert gases which do not chemically react with the molten metal. Metal active gas welding (MAG) is a form of gas metal arc welding that uses reactive gases to deliberately alter the composition of the molten metal.The addition of such an active gas enables, for example, a locally selective change in the properties of the screw vane; for example, the area of ​​the outer edge or the area of ​​the conveying flank of the screw vane can be made with a greater material hardness than radially more inward areas of the screw vane, which have tougher material properties.

[0034] One advantage of such an additively manufactured screw flight is that, to mitigate expected wear at specific points, for example, on the conveying flank, particularly on the furthest flank in the conveying direction, more material can be applied and / or a harder and / or more wear-resistant, especially higher-grade, material can be used compared to the material used elsewhere. Applying metallic sheets that comprise or consist of different materials offers the advantage that different materials can be used for different areas of the screw flight, with the materials being adapted to the specific requirements defined for each area.

[0035] According to a preferred embodiment, the screw flight is constructed in layers, obtained by: applying several metallic layers by melting a metal wire, wherein the layers are arranged parallel to each other and run along the thread direction of the screw flight.

[0036] Preferably, metal sheets are applied to the shaft by means of weld overlay. This weld overlay can be automated. Several metal sheets can be applied parallel to one another. Advantageously, the sheets run in the thread direction of the worm gear.

[0037] It is preferred that the screw flight has a layered structure, obtained by: applying a metallic layer by melting a metal wire, wherein the layer preferably runs along the thread direction of the screw flight, and preferably applying at least one further layer which is arranged parallel to the applied layer and in a layer with the previously applied layer, determining the height of the applied layer in the radial direction, applying a metallic layer by melting a metal wire in a layer radially above the already applied layer, wherein the positions at which the metal wire is melted to apply this layer depend on the previously determined height of the applied layer, and preferably applying several radially arranged layers one above the other, each with at least one layer, until a target height is reached and / or exceeded.wherein preferably before applying each new layer the height of at least one layer of the previously applied layer is determined in the radial direction.

[0038] It is further preferred that the screw conveyor has several, preferably two, screw flights arranged circumferentially offset from one another, in particular 180° offset from one another, thus forming a screw channel between them. In this case, a screw flight then forms two screw channels between two of its screw turns. A screw conveyor with one helically rotating screw flight thus forms a single-start screw conveyor, a screw conveyor with two screw flights a double-start screw conveyor, and generally a screw conveyor with n screw flights an n-start screw conveyor. It should be understood that the pitch of the screw corresponds to n times the screw pitch.

[0039] The screw flights and the screw channels are preferably of uniform design, with each screw flight preferably having a plurality of recesses in its outer circumferential edge, spaced apart from one another along the outer circumferential edge of the screw flight. The recesses of one screw flight are also preferably arranged axially offset from the recesses of another screw flight.

[0040] The screw conveyor is preferably designed with multiple starts, preferably with two starts. In particular, it is preferred that the screw conveyor is designed with multiple starts and thus has several screw flights. The screw conveyor is preferably designed with two starts, such that the screw conveyor has several, preferably two, screw flights, which preferably have the same shape and are arranged circumferentially offset from each other by 180°. A two-start design is understood to mean, in particular, that the screw conveyor has two screw flights.

[0041] In a two-flight screw conveyor, a new screw flight begins at 180°, and in a three-flight screw conveyor, a new flight begins at every 120°. The beginnings of the screw flights are therefore offset from each other by 180° or 120°, respectively.

[0042] Furthermore, it is preferred that at least one recess is arranged in the circumferential direction within an angular range of 360°, preferably at least two recesses are arranged, and particularly preferably at least three recesses are arranged.

[0043] 360° corresponds in particular to a full rotation around the axis of rotation.

[0044] The number of recesses is preferably at least or exactly two, and particularly preferably at least or exactly three, on each screw flight per full revolution. The total number of recesses on a screw flight can be determined by multiplying the number of recesses per full revolution by the number of revolutions of the screw flight.

[0045] It is particularly preferred if the recesses each have a longitudinal extension along a recess longitudinal axis, wherein the recess longitudinal axis is inclined, in particular at an angle of at least 2.5° or at least 5°, preferably at least 10°, to the thread direction of the screw flight. The recess longitudinal axis is preferably inclined to the thread direction of the screw flight such that, compared to the thread direction of the screw flight, the recess longitudinal axis is oriented further in the axial direction, in particular at an angle of at least 5°, preferably at least 10°.

[0046] Such a design means in particular that the longitudinal extent of the recesses is aligned further in the axial direction compared to the thread direction of the worm gear.

[0047] With such an inclined arrangement of the recesses, it can advantageously be achieved that, compared to an arrangement of the recesses in the thread direction, fewer recesses and / or shorter recesses are sufficient to completely and without interruption sweep over a cylinder spanned by the recesses when the screw flight rotates around the axis of rotation.

[0048] Furthermore, an advantage of such an inclined arrangement of the recesses is that the cleaning effect of a sieve device of a separator is improved due to this inclined arrangement compared to a non-inclined arrangement.

[0049] It is even more preferred that the recesses each have a length in the thread direction of the screw flight and a width in the width direction of the screw flight, and that the length is at least twice as large as the width, wherein preferably the length of the recesses is at least half as long, preferably at least as long as the distance between the recesses.

[0050] The length of the recesses and the distance between the recesses are preferably chosen such that, during a full rotation of the screw conveyor around the axis of rotation, every point of a surface of rotation spanned by the outer circumference of the screw flight is swept over by at least one of the recesses.

[0051] One advantage of recesses designed and arranged in this way is that, when the screw conveyor is used in a separator device, the inner wall of the screen, which forms the rotating surface, can be completely covered by the solids collected in the recesses. This allows for continuous cleaning of the screen by the solids and prevents blockages of liquid passages within the screen.

[0052] The recesses are preferably arranged circumferentially on the screw flight at uniform intervals. Preferably, the distance between adjacent recesses is the same.

[0053] Preferably, the recesses each have an opening in the outer edge of the screw wing, wherein the opening has a contour with several, preferably at least two acute angles, preferably with an angle of less than 90°, particularly preferably with an angle of less than 60°.

[0054] The recesses preferably have openings on the outer circumferential surface of the screw flight and form pocket-shaped material recesses in the screw flight. The openings preferably have several, in particular acute-angled, edges. With such acute-angled edges, solids can be particularly preferably picked up by the recesses and held in the recesses during rotation, especially by clamping fibrous solids.

[0055] Furthermore, it is preferred that the cross-sectional profile of the worm blade has at least one, preferably two, negative flank angles.

[0056] A flank angle is understood to be, in particular, the angle between a side surface, which can be specifically referred to as a flank, and a plane perpendicular to the axis of rotation. The flank angle can be negative on both the conveying side and the opposite side of the screw flight. With a negative flank angle, the cross-section of the screw flight widens radially outwards. In contrast to such a negative flank angle, screw threads generally have positive flank angles (often between 30° and 60°). It is particularly preferred if the negative flank angle has an angular magnitude of at least 5°, preferably at least 10°, and most preferably at least 15°. With correctly selected welding parameters, such flank angles can still be achieved with a nozzle longitudinal axis of the welding head that is perpendicular to the axis of rotation or to the circumferential surface of the shaft.By pivoting the nozzle's longitudinal axis, larger flank angles become possible.

[0057] It is particularly preferred if the flank angle is not constant, in particular if it is negative in one section and is 0° in at least one section, preferably in two sections. A flank angle of 0° is understood to mean, in particular, a flank extending exactly in the radial direction, i.e., lying in a plane perpendicular to the axis of rotation.

[0058] Preferably, the worm gear has an inner diameter and an outer diameter, and the worm gear is wider in the region of the outer diameter than in the region of the inner diameter. Preferably, the worm gear is at least 1.5 times wider, and particularly preferably at least twice as wide, in the region of the inner diameter.

[0059] Such a structure, widening outwards, can be manufactured particularly advantageously using additive manufacturing. In contrast, producing such a structure would be technically complex, requiring significantly higher material consumption with machining and a complex shape due to undercuts with casting.

[0060] It is further preferred that the screw conveyor has a casing that tapers from a first end of the screw conveyor to a second end, preferably conically. Such a screw conveyor can be manufactured particularly advantageously using an additive manufacturing process. The tapered outer contour benefits from sealing by recesses, which allows for manufacturing the outer edge with larger tolerances. The tapered outer contour allows the screw conveyor to be used in a correspondingly tapered screen tube and enables axial adjustment for wear compensation.

[0061] According to a further aspect, the aforementioned problem is solved by a screw conveyor, in particular for a separator device for dewatering moist masses, comprising a shaft extending axially along an axis of rotation, a screw vane arranged helically around the shaft, connected to the shaft at its outer circumference, and extending axially along at least one section of the shaft, wherein the screw vane is an additively manufactured metallic structure, preferably obtained by wire-based additive manufacturing using arc welding, in particular by metal inert gas welding (MIG), preferably by metal active gas welding (MAG), and / or wherein the screw vane is layered, obtained by: applying several metallic layers by melting a metal wire,the tracks are arranged parallel to each other and run along the thread direction of the worm gear.

[0062] Particularly preferred embodiments of such a screw conveyor are described in connection with the other aspects described here, especially the first aspect. These preferred features and embodiments also represent preferred features and embodiments in connection with this aspect.

[0063] According to a further aspect, the aforementioned problem is solved by a separator device for dewatering moist masses, in particular slurry and / or digestate, comprising a drive shaft rotatably mounted about a drive axis, a screw conveyor according to at least one of the preceding claims, wherein the screw conveyor is connected to the drive shaft for transmitting torque from the drive shaft to the screw conveyor, a sieve device which encloses at least a part of the screw conveyor, wherein the sieve device has a liquid-permeable sieve wall for dewatering the moist mass.

[0064] The drive shaft preferably extends along the axis of rotation and is rotatably mounted about the axis of rotation. The drive shaft is preferably rotationally fixed to the shaft, so that the drive shaft can transmit torque to the shaft. The shaft can thus be driven by the drive shaft via torque transmission, causing it to rotate about the axis of rotation. The sieve device has a liquid-permeable sieve wall, which is designed such that liquids can pass through it. Solids, in particular solids with a certain minimum particle size, cannot pass through the liquid-permeable sieve wall.Thus, moist masses can be dewatered by allowing a liquid component of the moist masses to pass through the sieve device and the dewatered moist masses, which normally have a certain residual moisture, to be conveyed axially out of the separator device by the screw conveyor.

[0065] The separator device can preferably be equipped with a screw conveyor with an axially tapered outer casing, wherein the screen device preferably extends from a first end to a second end and has an inner wall rotationally symmetrical about the drive axis, the inner diameter of which also tapers from the first end to the second end, preferably conically, wherein the screw conveyor is preferably axially adjustable relative to the screen device by means of an axial adjustment device. This allows for readjustment of the screw conveyor to compensate for wear.

[0066] According to another aspect, the aforementioned problem is solved by a method according to claim 9.

[0067] Additive manufacturing refers in particular to a manufacturing process in which material is applied layer by layer to create a three-dimensional object.

[0068] The shaft can be additively manufactured or non-additively manufactured. Here, the screw conveyor is also referred to as additively manufactured if only a part of the screw conveyor, in particular the screw flights, is additively manufactured and, for example, the shaft is a non-additively manufactured component. The shaft is preferably a non-additively manufactured component.

[0069] The shaft preferably has a connection point for connection with a drive shaft, so that in particular a torque can be transmitted from a drive shaft to the shaft and the shaft can thus be set into rotational motion around the axis of rotation.

[0070] The worm gear is preferably additively manufactured and thus built up layer by layer. The metallic layers are preferably applied by melting a metal wire with a welding device and then allowing the molten metal to solidify at a predetermined position. In this way, a continuous metallic layer can be applied. It is preferred if several layers, for example, two layers, are applied helically side by side in a parallel pattern to the surface of the shaft. These parallel layers form a first layer. Preferably, a second layer is applied to this first layer in the same way, the second layer also comprising several parallel layers. Subsequently, preferably a third layer, and preferably further layers, each with several parallel layers, are applied.It is particularly preferred if the tracks in the different layers are all arranged parallel to each other.

[0071] It is particularly preferred if the number of webs per layer increases radially outwards, at least between two layers, and preferably between several layers. This allows the cross-sectional structure of the screw flight to widen radially outwards.

[0072] A particular advantage of such a method for manufacturing a screw conveyor is that no cooling is required during the additive application of the webs, since the webs are applied sequentially in a helical fashion, thus allowing enough time for the applied material to solidify and cool before more material is applied in the same area.

[0073] It is preferred if several worm gears, in particular two offset worm gears, are mounted on the shaft using this method. Preferably, the worm gears are of uniform shape.

[0074] According to the invention, the screw wing is constructed in layers such that the screw wing has several spaced-apart recesses on the outer circumference of the screw wing for receiving, in particular fibrous, solids.

[0075] According to the invention, the recesses in the screw flight are formed by interrupting the material application in the area of ​​the recesses during the layer-by-layer application of metallic sheets. Thus, the recesses can be created directly during the layer-by-layer application of the metallic sheets into the screw flight, without requiring a separate manufacturing step and / or subsequent removal of already applied material. By interrupting some of the metallic sheets, the shape of the recesses can be improved and / or tailored to individual requirements. Material removal is therefore not strictly necessary for creating the recesses. This also advantageously simplifies the manufacturing of the screw conveyor and reduces the number of manufacturing steps required for its production.

[0076] It is particularly preferred that the screw wing is constructed in layers such that the screw wing has a cross-sectional profile with a width in the area of ​​the outer circumference of the screw wing and a width in the area of ​​the inner circumference of the screw wing, and the width in the area of ​​the outer circumference of the screw wing is greater than the width in the area of ​​the inner circumference of the screw wing.

[0077] Preferably, in one layer, particularly in the first layer, fewer parallel metal tracks are applied in the area of ​​the inner circumference of the screw flight than in one of the radially outermost layers, particularly than in the radially outermost layer, in the area of ​​the outer circumference of the screw flight.

[0078] It is particularly preferred that the method comprises the following steps: determining the height of an already applied layer in the radial direction, applying a metallic layer by melting a metallic material such as a metal wire in a layer radially above the already applied layer, wherein the positions at which the metallic material is melted to apply this layer are adjusted depending on the previously determined height of the already applied layer, and preferably applying several layers arranged one above the other in the radial direction, each with at least one layer, until a target height is reached and / or exceeded, wherein preferably the height of at least one layer of the previously applied layer is determined in the radial direction before the application of each new layer.

[0079] When applying the metallic layers, the flow and solidification behavior of the applied material can depend on environmental conditions, particularly the ambient temperature and / or the shaft temperature. Therefore, the shape of the applied layers can be affected by these environmental conditions. Specifically, the radial height of the applied layers can be influenced by the environmental conditions, meaning that the applied layers may have different heights under varying environmental conditions.

[0080] One advantage of determining the radial height of an already applied layer in this way is that a layer can be positioned in a layer above an applied layer based on the determined height of the applied layer. This allows for the application of superimposed layers in such a way that the layers are applied radially at the desired height above the already applied layers. This advantageously avoids positioning the metal wire too high or too low during melting. The metal wire can then be melted in the correct position, particularly at the correct height in the radial direction, even under varying environmental conditions.

[0081] The number of layers can be predetermined. However, it is preferred that a target height in the radial direction is specified and the number of layers is determined as soon as the target height is reached and / or exceeded with a layer. This advantageously ensures that the predetermined height of the screw flights is achieved regardless of how the height of the applied layers turns out to be, which depends on the ambient conditions.

[0082] Furthermore, it is preferred that the height of the applied layer in the radial direction is determined by the following steps: placing a surface of a welding head or a metal wire protruding from a welding head, having a known length, onto a reference plane; applying a metallic layer by melting the metal wire; optionally re-placing the metal wire protruding from the welding head onto the reference plane to determine the length of the metal wire; placing the surface of the welding head or the metal wire onto the surface of the applied layer; and detecting the contact of the surface of the welding head or the metal wire with the surface, in particular by detecting a contact force or detecting an electrical connection between the surface of the welding head or the metal wire and the applied layer.Determining the position of the surface of the applied web depending on the position of the welding head when the surface of the welding head or the metal wire is placed on the applied web and, if applicable, on the length of the metal wire.

[0083] In principle, by placing a surface of the welding head onto the surface of a welded path, the geometric position of the welded path's surface can be determined in a repeatable manner, and consequently, the height of the welded path in the radial direction can be determined. By placing a metal wire of known length protruding from a welding head onto the reference plane, the position of the wire can be determined by detecting a current flow during this placement. This allows, in particular, the position of the welding head in which the metal wire is held to be known for manufacturing purposes. With the known position of the wire, a path with predefined positional data can then be applied.After the metallic web has been applied, the metal wire can again be placed on the reference plane. For example, upon detection of a current flow, the contact of the metal wire with the reference plane is detected, and thus the length of the metal wire—which may have changed after the welding process—can be determined by determining the position of the welding head. It is particularly preferred if the height of the applied metallic web is subsequently determined by placing the metal wire on the surface of the applied web and detecting this contact, especially by sensing a contact force or an electrical connection between the metal wire and the applied web.In particular, when placing the metal wire onto the applied layer, the height of the applied layer can be determined in the radial direction due to the known length of the metal wire and the known position of the welding head.

[0084] These process steps for determining the height of an applied metallic layer can be performed after the application of each layer and / or each layer and / or at a different frequency. Depending on the determined height, the positioning of the subsequently applied layer can then be adjusted.

[0085] It is even more preferred that the screw conveyor is manufactured using wire-based additive manufacturing by means of arc welding, in particular by means of metal inert gas welding (MIG), preferably by means of metal inert gas welding (MIG) and / or metal active gas welding (MAG), using at least one welding robot.

[0086] It is preferred that the additive manufacturing of the screw blade be automated using the welding robot and digital production data.

[0087] It is even more preferred that the method comprises: machining the removal of additively applied material on the outer circumference of the screw wing to reduce the roughness of the screw wing on the outer circumference of the screw wing and / or to produce a straight outer edge on the outer circumference of the screw wing, and preferably machining the removal of additively applied material on the flanks of the screw wing to reduce the roughness of the screw wing on the flanks of the screw wing.

[0088] Preferably, after the metallic tracks have been applied, the additively manufactured screw flight undergoes mechanical post-processing. This mechanical post-processing can, in particular, reduce surface waviness and / or surface roughness. Specifically, such mechanical post-processing can create a circumferential edge on the outer circumference of the screw flight that is straight and parallel to the axial direction.

[0089] The flanks of the snail's wing refer in particular to the lateral outer surfaces of the snail's wing.

[0090] Furthermore, it is preferred that the shaft is clamped in a holder and is movable by means of movement of the holder, in particular rotatable about the axis of rotation, and / or that the at least one welding robot has at least six electromechanically driven axes.

[0091] It is particularly preferred that the layer-by-layer construction of the screw wing is carried out by applying parallel layers, wherein the layers run along the thread direction of the screw wing, wherein preferably a part of the layers is continuous along the entire screw wing and / or a part of the layers has interruptions in the area of ​​the recesses and is not continuous along the entire screw wing and / or a recess is formed by the course of the layers.

[0092] By means of such a layered construction of the screw flight, recesses can be advantageously introduced into the structure by interrupting the applied layers. This requires fewer manufacturing steps and less material compared to the conventional production of similar recesses. The individual layers can, for example, be arranged such that in a first region of the outer circumference they run as a number N parallel layers, while in a second region they run as a number N minus M parallel layers, where M is an integer of at least 1. This difference in the number of parallel layers can be achieved by appropriately starting and ending layers and results in the formation of recesses on the outer circumference of the screw flight.The first and second sections can always be arranged alternately along the circumference. Preferably, two of the webs can run parallel in the first section, one of which starts in the application direction before the first section and / or one of which ends in the application direction after the first section. Furthermore, preferably, a web can extend over the first and second sections and, in a transition section between the first and second sections, have a course oriented obliquely to the parallel direction. This allows for a precise delineation of a cutout. Furthermore, an advantageous cutout contour with one or two acute angles is achieved, which leads to advantageous fiber entanglement in the recess.

[0093] Furthermore, it is preferred that the number of parallel tracks in the area of ​​the inner diameter of the screw flight is less than the number of parallel tracks in the area of ​​the outer diameter of the screw flight.

[0094] It is preferred that the number of webs per layer increases radially outwards. This allows for a screw flight structure that widens outwards, even with webs of essentially the same cross-section.

[0095] Furthermore, it is preferred that the method comprises the following steps: creating production data for positioning the melting of the metal wire during the application of the web, comprising the steps of: creating a digital basic structure that represents cross-sectional information, in particular comprising a target height and a height-dependent width, of a screw flight, replicating the digital basic structure in a predetermined thread movement that corresponds to the thread shape of the screw flight.

[0096] It is preferred that the digital structure includes information about the cross-section of the screw flight. The number of webs per layer can then be determined as a function of the height of the respective layer and the width of the cross-section to be produced at that height, preferably during the manufacturing process, and in particular multiple times, for example, for each layer before the production of each layer. In particular, the number of layers can be determined as a function of the total height of the specified cross-section. A comparison between the target and actual height can preferably be carried out after the production of individual layers, and in particular after the production of each layer.

[0097] It is particularly preferred that the geometry of the screw conveyor is programmed into mathematical functions within a robot controller. Preferably, several coordinate transformations are performed so that each point on the surface of the individual screw flights can be addressed via the longitudinal and transverse directions of the flights. Swivel, rotation, and axis positions for a welding robot intended for additive manufacturing can be directly calculated through these coordinate transformations. Preferably, path planning for the applied metallic traces is performed exclusively in the longitudinal and transverse directions of the screw flights.

[0098] It is particularly preferred if the machining begins at a specific minimum radius. Preferably, from a certain limit radius, the screw flight widens in the transverse direction, with the area between the limiting flanks being automatically filled if one or more metallic layers can be applied. Preferably, from a further specified limit radius, the width in the transverse direction remains constant, with the area between the limiting flanks being automatically filled if one or more metallic layers can be applied. Preferably, from a certain radius, the screw flights are no longer completely filled but are provided with recesses. For this purpose, an algorithm is preferably defined that performs the outlining of recesses and the filling of the spaces between them for specific heights and positions on the screw flight.Preferably, the processing is completed once a certain radius is reached.

[0099] It is particularly preferred to apply the layers completely one after the other, especially to first apply one layer completely and then to apply the next layer completely, in order to keep the heat input as uniform as possible.

[0100] According to another aspect, the aforementioned problem is solved by using a screw conveyor as described here in a separator device, preferably a separator device as described here, for dewatering moist masses, in particular for dewatering digestate and / or slurry.

[0101] The aspects described above and their respective possible further trainings exhibit characteristics or procedural steps that make them particularly suitable for being produced using a procedure and its further trainings described here.

[0102] For the advantages, design variants and design details of the various aspects of the solutions described here and their respective possible further developments, reference is also made to the description of the corresponding features, details and advantages of the other aspects and their further developments.

[0103] Preferred embodiments are explained by way of example with reference to the accompanying figures. These show: Fig. 1: a schematic perspective view of a section of a screw conveyor with two screw flights arranged 180° apart from each other, showing only a section of half a turn of the two screw flights; Fig. 2: a schematic side view of the in Fig. 1 The section of a screw conveyor shown, with two screw flights arranged 180° apart from each other, is shown; Fig. 3: a schematic side view of the screw conveyor shown in ... Fig. 1 The section of a screw conveyor shown, with two screw flights arranged 180° apart from each other, is shown; Fig. 4: a schematic view in the direction of the axis of rotation of the screw. Fig. 1 Fig. 5a: a section of a screw conveyor with two screw flights arranged 180° apart; Fig. 5b: a schematic view of a first intermediate state of a screw conveyor during manufacturing; Fig. 5c: a schematic view of a third intermediate state of a screw conveyor during manufacturing; Fig. 6: a schematic representation of a separator device with a screw conveyor; Fig. 7: an exemplary schematic sequence of a method for the additive manufacturing of a screw conveyor.

[0104] In the figures, identical or essentially functionally equivalent or similar elements are designated with the same reference symbols. Dashed, gray lines in the figures indicate contours that are obscured by a component.

[0105] Fig. 1 Figure 1 shows a schematic perspective view of a section of a screw conveyor 10 with two screw flights 20, 30 arranged 180° apart from each other, showing only a section of half a turn of the two screw flights. A screw conveyor described here can be significantly longer than shown in the illustrations (where it is only shown in part), in which case each screw flight has several turns around the shaft 11. The screw flights are arranged helically on the shaft 11 and were applied to the shaft 11 layer by layer using additive manufacturing. The width of the screw flights 20, 30 is smaller on the inner circumference than on the outer circumference. On the outer circumference, the screw flight 20 has several spaced-apart recesses 21.The screw flight 30 also has several spaced-apart recesses. The screw flights have a cross-sectional profile with a width in the region of the outer circumference 20c of the screw flight 20 and a width in the region of the inner circumference 20a of the screw flight 20. The width 20c in the region of the outer circumference of the screw flight is greater than the width 20a in the region of the inner circumference of the screw flight. A central region 20b is arranged between the inner and outer regions, in which the cross-section widens radially outwards.

[0106] Fig. 2 shows a schematic side view of the in Fig. 1 The section shown depicts a screw conveyor with two screw flights 20, 30 arranged 180° apart from each other, mounted on a shaft 11. The shaft 11 can be rotatably mounted about an axially extending axis of rotation 300. The shaft 11 is cylindrical and hollow. The shaft 11 has an outer circumference 11a and an inner circumference 11b (shown by a gray dashed line).

[0107] Fig. 3 shows a schematic side view of the in Fig. 1-2 The section shown is of a screw conveyor with two screw flights 20, 30 arranged 180° apart from each other. The section shown is the one in Fig. 2 The section shown, however, the screw conveyor differs from the illustration in Fig. 2 rotated 90° around the axis of rotation 300.

[0108] Fig. 4 shows a schematic view in the direction of the axis of rotation of the in Fig. 1-3 The section shown depicts a screw conveyor with two screw flights arranged 180° apart. The radially widening cross-section or cross-sectional profile of the screw flights 20, 30 is visible.

[0109] The negative flank angle α is shown in the diagram of the snail wing 20. The area where the flank angle α is negative is located between a radially inner and a radially outer region, where the flank angle is not negative but 0° in the radially inner and radially outer regions.

[0110] Fig. 5a Figure 1 shows a schematic view of an initial intermediate state of a screw conveyor during its manufacture. The first layers 20a and 30a, each consisting of several parallel metallic tracks, have been applied to the shaft. These layers were applied radially outwards, one on top of the other.

[0111] Fig. 5b This shows a schematic view of a second intermediate state of a screw conveyor during its manufacturing. According to the in Fig. 5a In the state shown, further layers 20b, 30b, which become wider radially outwards, were applied layer by layer.

[0112] Fig. 5c This shows a schematic view of a third intermediate state of a screw conveyor during its manufacturing. According to the in Fig. 5b In the state shown, further layers 20c, 30c, positioned in the area of ​​the outer circumference of the screw flights 20, 30, were applied layer by layer. During the application of the metallic layers, the metallic tracks in the area of ​​the recesses 21 were interrupted, so that the recesses were created during the additive manufacturing of the screw flights without the need for subsequent milling or other mechanical processing.

[0113] Fig. 6 Figure 1 shows a schematic sectional view of a preferred embodiment of a separator device 200. The separator device 200 is designed to dewater a moist mass M in order to provide a dewatered mass S with a desired dry matter content. For this purpose, the separator device 200 has a drive shaft 50 rotatably mounted about an axis of rotation, which extends in an axial direction. The drive shaft 50 is driven by a motor shaft of a drive unit 40.

[0114] To convey the moist mass M to be dewatered in a conveying direction F and to separate the liquid L from the mass M to be dewatered in order to provide a dewatered mass S with a desired dry matter content, a screw conveyor 10 is rotatably arranged within a sieve device 70, so that the sieve device 70 surrounds the screw conveyor 10.

[0115] The screw conveyor 10 and the sieve 70 are designed such that the screw conveyor 10 rests closely against the sieve 70, in particular against an inner surface of a fluid-permeable sieve wall of the sieve 70. This arrangement compresses the moist mass M to be dewatered via an inlet chamber 51 in the conveying direction F between the screw conveyor 10 and the sieve 70, depending on the applied conveying pressure. This causes the liquid L to be forced from the moist mass M through the fluid-permeable sieve wall of the sieve. The fluid-permeable sieve wall has outlet openings that extend between the inner surface of the sieve wall facing the screw conveyor 10 and an outer surface of the sieve wall that is radially outward from the inner surface and facing away from the screw conveyor 10.The liquid L, separated from the moist mass M, can exit the sieve device 70 through the outlet openings and be collected in a container 61. The dewatered mass S exits the separator device and can, for example, be collected in a container 62.

[0116] The size of the outlet openings is designed such that the liquid L, but not the solids of the moist mass M, can escape through the sieve wall from the sieve device 70, so that the solids of the moist mass M are guided through the sieve device 70 to an outlet.

[0117] Fig. 7 An exemplary schematic sequence of a process 100 for the additive manufacturing of a screw conveyor, wherein the manufacturing of the screw conveyor is carried out by means of wire-based additive manufacturing using metal inert gas (MIG) welding with a welding robot, comprising the following steps: In step 101, a shaft extending axially along an axis of rotation is provided. In step 102, a worm gear is additively manufactured on the shaft by layer-by-layer material deposition, comprising steps 102a, applying a metallic track by melting a metal wire, the track preferably running along the thread direction of the worm gear, and 102b, applying further tracks arranged parallel to the applied track. The worm gear is built up layer by layer such that it has a cross-sectional profile with a width in the region of the outer circumference and a width in the region of the inner circumference, the width in the region of the outer circumference being greater than the width in the region of the inner circumference.Furthermore, the screw flight is built up layer by layer such that the screw flight has several spaced-apart recesses on its outer circumference for receiving solids, particularly fibrous materials. In step 103, the height of an already applied layer in the radial direction is determined, wherein the height of the applied layer in the radial direction is determined by the following steps: placing the metal wire, which has a known length, on a reference plane, applying a metallic layer by melting the metal wire, re-placing the metal wire on the reference plane to determine the length of the metal wire, placing the metal wire on the applied layer, and determining the height of the applied layer as a function of the position of the metal wire when placing it on the applied layer and of the length of the metal wire.Based on the determination of the actual thickness of an applied layer, it is also possible to specify a target application thickness and calculate the number of layers required to achieve this target thickness. In step 104, a metallic web is applied by melting a metal wire in a layer radially above the already applied web, wherein the positions at which the metal wire is melted to apply this web are adjusted depending on the previously determined thickness of the already applied web. In step 105, several radially arranged layers, each with at least one web, are applied until a target thickness is reached and / or exceeded, wherein preferably the thickness of at least one web of the previously applied layer is determined radially before the application of each new layer.In step 106, additively deposited material is removed from the outer circumference of the screw flight to reduce the roughness of the screw flight on its outer circumference and / or to create a straight outer edge on the outer circumference of the screw flight. In step 107, additively deposited material is removed from the flanks of the screw flight to reduce the roughness of the screw flight on its flanks. Bezugszeichenliste

[0118] 10: Screw conveyor 11: Shaft 11a: Outer circumference of the shaft 11b: Inner circumference of the shaft 20, 30: Screw flight 20a, 30a: Radial inner area of ​​the screw flight 20b, 30b: Radial area of ​​the screw flight located between the inner and outer areas 20c, 30c: Radial outer area of ​​the screw flight 21, 31: Recesses 40: Drive motor 50: Drive shaft 51: Inlet chamber 61: Liquid container 62: Solid container 70: Sieve device 100: Method for the additive manufacturing of a screw conveyor 101-107: Process steps 200: Separator device 300: Axis of rotation a: Negative flank angle F: Conveying direction M: Moist mass S: Dewatered mass L: Liquid

Claims

1. Screw conveyor (10), in particular for a separator device (200) for dewatering moist masses, comprising - a shaft (11), which extends in axial direction along an axis of rotation (300) and which is preferably not manufactured in an additive manufacturing process, wherein the shaft comprises or consists of metallic material, preferably steel, in particular stainless steel, - a screw flight (20, 30), which ∘ is arranged helically around the shaft, ∘ is connected to the shaft at the outer circumference of the shaft, ∘ and extends in an axial direction along at least a portion of the shaft, characterized in that the screw flight is a metallic structure additively manufactured on the shaft and has, on the outer circumference, an outer edge, in which a plurality of recesses spaced from each other for receiving fibrous materials are arranged, wherein the recesses are formed in the screw flight by interrupting the material application in the area of the recesses during the layer-by-layer application of metallic paths.

2. Screw conveyor according to the preceding claim, characterized in that the screw flight is produced by wire-based additive manufacturing by means of arc welding, in particular by means of gas metal arc welding (GMAW), preferably by means of metal inert gas welding (MIG) and / or metal active gas welding (MAG).

3. Screw conveyor according to at least one of the preceding claims, characterized in that the screw flight is built up in layers obtained by: - Applying of several metallic paths by means of melting off a metal wire, wherein the paths are preferably arranged parallel to one another and run along the thread running direction of the screw flight.

4. Screw conveyor according to at least one of the preceding claims, characterized in that the screw conveyor has several, preferably two, screw flights (20, 30), which are arranged offset from one another in the circumferential direction, in particular offset from one another by 180°, and are preferably of uniform design, wherein preferably each of the screw flights has a plurality of recesses in circumferential direction and the recesses of one screw flight are offset in axial direction from the recesses of another screw flight, and / or that in the screw flight in circumferential direction within an angular range of 360° at least one recess is arranged, preferably at least two recesses are arranged, particularly preferably at least three recesses are arranged, and / or in that each screw flight has several spaced recesses and the recesses each have a longitudinal extension along a recess longitudinal axis, wherein the recess longitudinal axis being oriented obliquely, in particular at an angle of at least 2.5°, preferably at least 10°, relative to a thread running direction of the screw flight, so that compared to the thread running direction of the screw flight the recess longitudinal axis is oriented further, in particular at an angle of at least 5° relative to the thread running direction, preferably at least 10° relative to the thread running direction, in direction of the axial direction.

5. Screw conveyor according to at least one of the preceding claims, characterized in that each screw flight has several spaced recesses and - the recesses each have a length in the thread running direction of the screw flight and a width in the width direction of the screw flight, and the length is at least twice as great as the width, wherein preferably the length of the recesses is at least half as long, preferably at least as long, as the distance between the recesses, and / or - the length of the recesses and the distance between the recesses are selected such that, during one full rotation of the screw conveyor about the axis of rotation, each point of a surface of rotation spanned by the outer circumference of the screw flight is swept by at least one of the recesses, and / or - the recesses are arranged at a uniform distance from each other in the circumferential direction on the screw flight, and / or - the recesses each have an opening in the outer edge of the screw flight, wherein the opening has a contour with several, preferably at least two, acute angles, preferably with an angle less than 90°, particularly preferably with an angle less than 60°.

6. Screw conveyor according to at least one of the preceding claims, characterized in that the screw flight has a cross-sectional profile with a width in the region of the outer circumference of the screw flight and a width in the region of the inner circumference of the screw flight, and the width in the region of the outer circumference of the screw flight is greater than the width in the region of the inner circumference of the screw flight, and / or that the cross-sectional profile of the screw flight has a negative flank angle on at least one side, preferably on both sides in at least one section, for example in the form of a linear course of the cross-sectional profile side or in the form of a course of a continuous function such as a parabola, and / or in that the screw flight has an inner diameter and an outer diameter and the screw flight is formed wider in the region of the outer diameter than in the region of the inner diameter, wherein preferably the screw flight is formed at least twice as wide in the region of the outer diameter as in the region of the inner diameter, and / or that the screw conveyor has an envelope which tapers, preferably conically tapers, from a first end of the screw conveyor to a second end of the screw conveyor.

7. Separator device for dewatering moist masses, in particular liquid manure and / or digestates, comprising - a drive shaft (50) rotatably mounted about a drive axis of rotation, - a screw conveyor (10) according to at least one of the preceding claims, wherein the screw conveyor is connected to the drive shaft for torque transmission from the drive shaft to the screw conveyor, - a screening device (70) which encloses at least part of the screw conveyor, wherein the screening device has a liquid-permeable screen wall for dewatering the moist mass.

8. Separator device according to claim 7 with a screw conveyor according to claim 6, characterized in that the screening device extends from a first end to a second end and has an inner wall which is rotationally symmetrical about the drive axis of rotation, whose inner diameter tapers, preferably conically tapers, from the first end to the second end, wherein preferably the screw conveyor is axially adjustable relative to the screening device by means of an axial adjustment device.

9. A method of manufacturing a screw conveyor (100), in particular a screw conveyor according to at least one of claims 1-6, comprising the steps: - Providing (101) a shaft, which extends in axial direction along an axis of rotation, preferably as machined or mastershaped preformed shaft, wherein the shaft comprises or consists of metallic material, preferably steel, in particular stainless steel, - additive manufacturing (102) of a screw flight on the shaft by layer-by-layer material deposition, comprising: ∘ Applying (102a) a metallic path by means of melting a metal material, preferably a metal wire, wherein the path preferably extends along a thread running direction of the screw flight, ∘ and preferably Applying (102b) further paths, which are arranged parallel to the applied path, characterized in that the screw flight is built up in layers in such a way that the screw flight has, on the outer circumference of the screw flight, several recesses spaced apart from one another for receiving, in particular fiber-containing, solids.

10. Method according to the preceding claim, characterized in that the screw flight is built up in layers in such a way that the screw flight has a cross-sectional profile with a width in the region of the outer circumference of the screw flight and a width in the region of the inner circumference of the screw flight and the width in the region of the outer circumference of the screw flight is greater than the width in the region of the inner circumference of the screw flight.

11. Method according to at least one of the preceding claims 9-10, comprising the steps: - Determining (103) the height of an already applied path in radial direction, - Applying (104) a metallic path by means of melting a metal material, preferably a metal wire, in a layer lying radially above the already applied path, wherein the positions at which the metal material is melted off for application of this path is set in dependence of the previously determined height of the already applied path, - and preferably Applying (105) several layers arranged one above the other in radial direction, each having at least one path, to form a layer stack until the layer stack reaches and / or exceeds a nominal height, wherein preferably before the application of each new layer the height of at least one path of the previously applied in radial direction is determined.

12. Method according to at least one of the preceding claims 9-11, characterized in that the determination of the height of the applied path in radial direction is performed by means of the following steps: - Placing a surface of a welding head or a metal wire protruding from a welding head, which has a known length, on the surface of the applied path, in particular by detecting a contact force or detecting an electrical connection between the welding head or the metal wire and the applied path, - Determining the position of the surface of the deposited path in dependence of the position of the welding head when placing the metal wire on the applied path and, if necessary, of the length of the metal wire, and / or that the determination of the height of the applied path in radial direction is performed by means of the following steps: - Placing a surface of a welding head or a metal wire protruding from a welding head, which has a known length, on a reference plane, - Applying of a metallic path by means of melting the metal wire, - If necessary, again placing the metal wire protruding from the welding head on the reference plane for determination the length of the metal wire, - Placing the surface of the welding head or the metal wire on the surface of the applied path and detection of the placement of the surface of the welding head or the metal wire on the surface, in particular by detecting a contact force or detecting an electrical connection between the surface of the welding head or the metal wire and the applied path, - Determining the position of the surface of the applied path in dependence of the position of the welding head during placing of the surface of the welding head or the metal wire on the applied path and, if necessary, on the length of the metal wire.

13. Method according to at least one of the preceding claims 9-12, characterized in that the manufacturing of the screw conveyor takes place by wire-based additive manufacturing by means of arc welding, in particular by means of metal inert gas welding (MIG), preferably by means of metal inert gas welding (MIG) and / or metal active gas welding (MAG), by means of at least one welding robot.

14. Method according to at least one of the preceding claims 9-13, the method comprising - Chip removal (105) of additively applied material at the outer circumference of the screw flight for reduction of the roughness of the screw flight at the outer circumference of the screw flight and / or for production of a straight outer edge at the outer circumference of the screw flight, - and preferably chip removal (106) of additively applied material on the flanks of the screw flight for reduction of the roughness of the screw flight on the flanks of the screw flight.

15. Method according to at least one of the preceding claims 9-14, characterized in that the shaft is clamped in a holder and is movable, in particular rotatable about the axis of rotation, by means of movement of the holder, and / or that the at least one welding robot has at least two preferably electromechanically driven axes.

16. Method according to at least one of the preceding claims 9-15, characterized in that in that the layered buildup of the screw flight is carried out by means of application of paths arranged in parallel, wherein the paths run along the thread direction of the screw flight, wherein preferably a part of the paths is formed continuously along the entire screw flight in each case and / or a part of the paths has interruptions each case in the region of the recesses and is not formed continuously along the entire screw flight and / or a recess is formed by the course of the paths, and / or that the number of parallel paths in the area of the inner diameter of the screw flight is less than the number of parallel paths in the area of the outer diameter of the screw flight.

17. Method according to at least one of the preceding claims 9-16, comprising - Creating production data for the positioning of the melting off of the metal wire when applying the path, comprising the steps: ∘ Creating of a digital basic structure mapping cross-sectional information, in particular comprising a nominal height and a width dependent on the height, of a screw flight, ∘ Replicating the digital basic structure in a predetermined threading motion that corresponds to the thread shape of the screw flight.

18. Use of a screw conveyor according to at least one of claims 1-6, in a separator device, preferably a separator device according to claim 7, for dewatering moist masses, in particular for dewatering digestates and / or liquid manure.