Displacer body and pump housing for a positive-displacement pump

Abstract

The invention relates to a rotary piston for a rotary piston pump, comprising a piston main structure, comprising a hub structure with a bearing circumferential surface which extends around the rotational axis of the rotary piston, and at least two piston vane structures which are connected to the hub structure, wherein the piston main structure is formed from a first, preferably metallic, material, and is preferably enclosed radially on the outside preferably with a second material which is different from the first material, in particular an elastomer material, characterized in that at least one cavity which is preferably gas-filled is formed in each case in a, preferably each, piston vane structure, which cavity is enclosed by a piston vane wall of the piston main structure and possibly also by an outer circumferential surface of the hub structure and which is free from elastomer material.

Description

[0001] Displacement body and pump housing for a positive displacement pump

[0002] The invention relates to displacement bodies and housings for positive displacement pumps, such as a rotary lobe and a pump housing for a rotary lobe pump or a rotor and a stator for an eccentric screw pump. Further aspects of the invention include manufacturing methods for these components. Rotary lobe pumps and eccentric screw pumps belong to the category of positive displacement pumps and are used to pump numerous types of media, including, in particular, contaminated and solids-containing media that contain abrasive particles. These media can be pumped with rotary lobe pumps and eccentric screw pumps, and the pumps achieve a long service life.For certain media, and especially for the particles entrained therein, it has proven effective to use rotary lobes with an outer rubber coating and stators with an inner rubber lining to prevent or at least reduce wear caused by particles trapped between the displacer and the housing. In other applications, rotary lobes and stators without such a rubber coating are also used.

[0003] For reliable, long-term operation, rotary lobe pumps and progressing cavity pumps require precise manufacturing of a complex geometric contour of the displacer body (rotary lobe, rotor) and the housing (rotary lobe pump housing, stator). At the same time, these components must withstand high operating forces and deform / bend as little as possible under these operating forces to ensure low-friction and low-wear operation. However, this desired high level of precision and stability is counteracted by the fact that a solid construction, which would achieve this high level of rigidity, would result in high weight and high material usage, which would complicate pump maintenance, increase manufacturing costs, and – in the case of eccentric movements such as those found in progressing cavity pumps – lead to significant unbalance forces and associated bearing stresses.

[0004] US 10,982,671 B1 discloses a rotary lobe for a rotary lobe pump, which has a metallic framework made of several sheet metal plates encased in a rubber-elastic material. This rotary lobe design allows for a significant reduction in the metallic portion of the rotary lobe while simultaneously maintaining good adhesion of the rubber-elastic portion of the rotary lobe to the metallic portion. This allows for a reduction in the weight of the rotary lobe without adversely affecting the integrity of the rotary lobe over its service life or causing delamination. A disadvantage of this design, however, is the complex prefabrication of the required metallic plates and their assembly on the prefabricated hub.In addition, this manufacturing method requires careful selection of processing parameters during the encapsulation with the rubber-elastic material to avoid undesirable concave surface indentations between the metal plates due to shrinkage of the rubber-elastic material during the vulcanization process. Therefore, implementing planned geometric changes to the rotary piston requires complex conversion or redesign of the manufacturing tools and careful redefinition of the manufacturing parameters for the vulcanization process.

[0005] EP 2 944 819 B1 discloses an eccentric screw pump in which the assembly and maintenance of the rotor is facilitated by an inclined flange enabling one-sided pivoting of the stator with the rotor arranged therein from an installed position. The rotor can therefore be pulled axially out of the stator in a simplified manner. This improvement aims to make the rotor more accessible and easier to handle, but does not lead to a reduction in the sheer mass of the rotor or stator for the purpose of simplifying handling. EP 3 1 12682 B1 describes an eccentric screw pump with a hollow rotor through which a fastening element for fastening the rotor to a wobble shaft is passed or made accessible. This design of the rotor reduces the weight of the rotor compared to a solid rotor.However, the production of such a rotor is more complex because the production of a bore over the entire length of such a rotor requires an additional production step, which is also complex.

[0006] EP 19749244 A1 discloses the production of a rotor using a multi-axis milling process or an SLS / SLM process, or, in the case of smaller eccentric screw rotors, using stereolithography or 3D printing from plastic material. These alternative manufacturing methods, compared to the previously common vortex process, enable the production of a rotor with an external geometry that can be designed to a greater extent than with the vortex process. However, the eccentric screw rotors produced in this way are advantageously designed, particularly with regard to their surface geometry. However, production using the SLS / SLM process is time-consuming, and these manufacturing methods are primarily suitable for small rotors.

[0007] DE 11 2017 000 580 T5 discloses a rotor for use in a Roots compressor, which is to be manufactured using a 3D printing or additive process. The rotor is equipped with reduced inertia with regard to the speed change behavior ("transient behavior") on the one hand, and optimized thermal expansion behavior to optimize the device's efficiency on the other. The rotor is to have a hollow lattice structure, resulting in a net-shaped or almost net-shaped rotor. A disadvantage here is that with the 3D printing process preferred in this prior art, such cavities cannot be produced gas-filled in the additive manufacturing process; instead, non-solidified raw material (powder, liquid) remains in the cavity and would therefore have to be subsequently removed through suitable openings in the cavity wall if the cavity is to be gas-filled.This is complex and often not completely successful, especially in the case of fissured or subdivided cavities. The cavity in the rotor is to be closed by a first and a second rotor end face. The rotors are designed for use as synchronously connected counter-rotating rotors in an expander with an oblique axial-radial flow direction. The disadvantages of this design are the axial-radial flow, which is unsuitable for many applications, and the insufficient load capacity of the rotors for conveying particle-laden liquids. EP 1 300 592 A2 discloses another rotary blower similar to a Roots compressor, in which a compressible medium, typically air, is compressed by two intermeshing rotors.The disadvantage of this design is that the precision of the rotor geometry required for conveying incompressible media for the purpose of conveying without leakage of the conveyed medium cannot be achieved.

[0008] DE 20 2016 100 894 U1 discloses an eccentric screw pump in which the stator casing or rotor is designed as 3D-printed parts. The disadvantage of this manufacturing process is the lengthy manufacturing process. A stator composed of several disc-shaped segments is proposed. However, this has the disadvantage that assembly is complex and the segments must be sealed to prevent unwanted leaks and efficiency losses.

[0009] A progressing cavity pump with a stator lining is previously known from DE 20 2021 106 537 U1. The stator lining is supported by a surrounding stator housing. This support is intended to create a location-dependent support effect by constructing the stator lining from a thin-walled sleeve and a support structure with a support effect adapted to the local requirements of the sleeve. A disadvantage of this design, however, is its high sensitivity to unexpected load peaks, for example, caused by foreign bodies or pressure peaks, which can irreversibly deform or perforate the thin-walled sleeve structure. Furthermore, the production time for stators designed in this way and the necessary multi-part design are unfavorable for efficient production.

[0010] Against this background, the object of the present invention is to simplify the maintenance effort on a positive displacement pump, such as a rotary lobe pump or an eccentric screw pump, even if it has a large delivery volume, and in doing so not to significantly increase the manufacturing effort for producing the positive displacement pump.

[0011] This object is achieved according to a first aspect of the invention by a rotary piston for a rotary piston pump, comprising o a hub structure with a bearing circumferential surface which extends around a rotation axis of the rotary piston, and o at least two piston vane structures connected to the hub structure, wherein the piston base structure is formed from a first, preferably metallic material, and is preferably radially outwardly enveloped with a second material different from the first material, in particular an elastomer material, characterized in that in one, preferably each piston vane structure in each case at least one preferably gas-filled cavity is formed, which is enclosed by a piston vane wall of the piston base structure and optionally by an outer circumferential surface of the hub structure and which is free of elastomer material.

[0012] The rotary piston according to the invention is characterized by at least one cavity arranged in each piston wing structure. The cavity can preferably be gas-filled. A two-wing rotary piston accordingly has at least two such gas-filled cavities, while a three-wing or multi-wing rotary piston accordingly has at least three and correspondingly more such gas-filled cavities. The gas-filled cavities are arranged in the piston wing structures and are thus eccentric and spaced from the axis of rotation of the rotary piston. Each cavity is enclosed, on the one hand, by an outer circumferential surface of the piston base structure, which is typically provided by a wall of the piston wing structure and prevents the introduction of rubber-elastic material during any subsequent coating process with an elastomer.The cavity in each rotary piston can be a self-contained cavity, but can also be designed to be radially open inward, so that the gas-filled cavities in the individual piston vane structures are fluidly connected to each other through a hollow central interior of the rotary piston. This design, in particular, also makes it possible to manufacture the rotary piston using a casting process, using cores that can be removed toward the axis of rotation after the casting process to form the cavity in the piston vane structure.

[0013] The rotary piston further comprises a hub structure with a bearing surface. In the simplest case, this can be formed by a flange connection surface, with which the rotary piston is connected to a drive shaft and thus supported. The bearing surface can also be formed by a cylindrical inner peripheral surface, with which the rotary piston can be attached to an outer peripheral surface of a shaft and thus supported.

[0014] A preferred method for producing the rotary piston over the casting method is an additive manufacturing method in which the basic piston structure is produced in an additive manufacturing process. According to the invention, an additive manufacturing method is understood to be any method in which a material is selectively applied point-by-point, line-by-line, or layer-by-layer and cured, and a product is thereby selectively constructed based on the geometric data, for example by selectively applying the material in a molten state and then solidifying it, or by selectively applying the material in a powdered state as a homogeneous layer or even already applied and solidified and bonded together by melting and solidifying at selectively selected locations. Examples of this are a three-dimensional printing method or a welding deposition method.These methods make it possible to enclose a cavity with a wall directly during the additive manufacturing process, thereby forming the gas-filled cavities as self-contained cavities. With other methods, such as laser sintering or laser melting processes, uncured powder material can be subsequently removed from such a cavity – or can remain there. Such a cavity filled with loose powder is also to be understood as a gas-filled cavity within the meaning of the invention. In principle, a cavity, or in particular a gas-filled cavity, within the meaning of the invention is to be understood as a volume that is not designed or suitable for absorbing or transmitting mechanical forces.

[0015] Accordingly, according to a first preferred embodiment, it is particularly preferred if the piston vane structure is partially or completely manufactured using an additive manufacturing process, preferably on an outer peripheral surface of the hub structure in a radial construction direction relative to the rotation axis. Typical additive manufacturing processes include, for example, deposition welding processes, in which the material is supplied in wire or powder form, selectively melted by an arc, laser, or other means, thereby solidifying and bonding it to the already manufactured substructure.Other additive manufacturing processes are three-dimensional printing processes with which a product is manufactured directly or indirectly, for example, directly by printing on curable polymer materials or indirectly by printing on curable polymer binder materials mixed with a metal or ceramic powder and subsequently melting the polymer binder and sintering the metal and ceramic components to form the final product. Other additive manufacturing processes that are considered for the invention are laser sintering or laser melting processes, in which a product is manufactured layer by layer by selectively curing a powder layer using a laser and bonding it to a previously cured structure in the underlying powder layer. This process is repeated until the product is completed by successively layering several such powder layers.

[0016] A key influencing factor in such additive manufacturing processes is the build direction along which the product is built up point by point, layer by layer, or region by region. This build direction is influenced on the one hand by the surface geometry of the product, since the surface may only lie at a certain maximum angle to the build direction to form an overhang. If this maximum angle is exceeded, a secure build with a connection of an upper layer with the structures of the underlying layer in an overhang structure can no longer be guaranteed. On the other hand, the build direction is also determined and limited by the shape of the build space of the respective manufacturing device used. According to the invention, it is preferred on the one hand to build the rotary piston in the axial direction, i.e. with a build direction along the axis of rotation of the rotary piston.In this case, in particular, the length of the rotary piston can be designed almost unlimitedly by appropriate vertical construction in a construction space on a horizontally limited construction platform and is only limited in the vertical direction by the height of the construction space. Alternatively, it is preferred to build the piston vane structure in a radial construction direction on an outer peripheral surface of the hub structure. In this case, a hub structure is prefabricated, which can be carried out using a conventional or additive manufacturing process, for example, in a machining process in a turning process. The piston vane structures are then manufactured in the radial direction on the outer peripheral surface of the hub structure produced in this way using the additive manufacturing process.This can be achieved by rotating the hub structure around the rotation axis of the rotary piston during the additive manufacturing process, thereby providing a degree of freedom of movement for the additive manufacturing process and thus enabling the additive manufacturing process to always be carried out on a top side with respect to the direction of gravity on the hub structure, thereby preventing undesired flow away of the additively applied material.

[0017] The structure of the rotary piston according to the invention is characterized in the first case by the fact that the layers of the piston vane structure are stacked one on top of the other in the axial direction, whereas in the second manufacturing method with a radial build-up direction on the hub structure, the layers are stacked one on top of the other in the radial direction. The rotary piston according to the invention can be further developed by one or more ribs extending through the cavity, with one or more ribs preferably extending through each cavity. Such ribs can effectively contribute to stiffening the structure and thus enable an overall thinner wall thickness while maintaining the same stiffness and strength. The ribs can preferably be constructed integrally in the additive manufacturing process of the rotary piston.The ribs may divide the cavity into two or more separate individual cavity sections that are not in fluid communication with each other, or may only partially protrude into the cavity, so that the cavity remains as a single cavity.

[0018] It is even further preferred if the at least two piston vane structures are arranged angularly offset from one another in the circumferential direction around the axis of rotation. Each piston vane structure has a piston vane root and a piston vane head arranged radially outwardly therefrom; a piston vane neck can also be arranged between them. The piston vane root, which is preferably arranged adjacent to the circumferential surface, has a vane foot width arranged centrally in the radial direction and extending circumferentially around the axis of rotation. The piston vane head and piston vane neck each have a vane head width arranged radially centrally and a vane neck width in the circumferential direction around the axis of rotation.In this embodiment, two piston wing structures are provided that are angularly offset from one another, for example, with exactly two piston wing structures, they are angularly offset by 180°. Preferably, the plurality of piston wing structures are evenly distributed over the circumference of the rotary piston. In principle, the wing head width can be smaller than the wing neck width and the wing base width, and the wing neck width can be smaller than or equal to the wing base width, resulting in a wing structure geometry corresponding to a house with a gable roof. In other embodiments, the wing neck width can also be smaller than the wing base width and the wing head width, resulting in a constricted shape, similar to an hourglass cross-section.This results in a constriction in the area of ​​the piston lobe neck, which also advantageously replicates the geometry of a piston lobe for a rotary piston and thus enables the rotary piston to be designed particularly lightly, with a large cavity in the piston lobe and with an outer geometry that is already well approximated to the desired geometry of the rotary piston or is in its final state, or with an outer geometry that can be coated with an elastomer layer of constant thickness. This geometric design enables, in particular, efficient production using a welded deposition process on a circumferential surface of the prefabricated hub structure, without creating overhangs or mounting angles that are impossible to manufacture or that are particularly sensitive to the manufacturing parameters.It is even further preferred if the cavity widths in the piston wing head, piston wing neck and piston wing root are designed according to the wing head, wing neck and wing root width, thus achieving a uniform wall thickness and good cavity utilization with a maximization of the cavity volume.

[0019] In the above embodiments, it should be understood that for a piston wing consisting of a piston wing head and a piston wing root, these two sections each take up half of the total radial height of the piston wing, and the head width and the root width are measured in the middle of the piston head and the piston root, respectively, i.e. in the radial direction at 1 / 4 and 3 / 4 of the radial height of the piston wing. If the piston wing is composed of a piston wing head, piston wing neck, and piston wing root, this should be understood to mean that each of these three sections takes up 1 / 3 of the total height of the piston wing in the radial direction, and the respective width of the respective section is measured in the middle of the section, i.e. at 1 / 6, 3 / 6, and 5 / 6 of the radial height of the piston wing.

[0020] It is further preferred if each of the at least two piston wing structures has a piston wing wall, which preferably encloses the cavity in the piston wing structure, and a plurality of structural ribs arranged on the piston wing wall outside the cavity, which are preferably produced using an additive manufacturing process. According to this embodiment, the piston wing structures have structural ribs arranged outside, i.e., outside the cavity, which can be geometrically independent of any ribs in the cavity. These structural ribs serve to create an enveloping contour of the rotary piston through their outer contour, which achieves good adhesion of a subsequently applied wrapping material, such as a rubber-elastic material.

[0021] It is particularly preferred if the structural ribs comprise one or more circumferential ribs that extend substantially along a circumferential direction with respect to the rotational axis over the piston vane wall and that preferably run parallel to one another, and / or comprise one or more axial ribs that extend substantially along an axial direction with respect to the rotational axis. According to this embodiment, the structural ribs can extend in the circumferential direction or in the axial direction with respect to the rotational axis of the rotary piston, or both structural ribs in the axial direction and structural ribs in the circumferential direction can be provided.This arrangement achieves effective form-fitting support and adhesive adhesion of a rubber-elastic material, with which the piston is coated, to the piston wing structure, thus preventing delamination of the rubber coating even under high loads and forces on the interface between the piston wing structure and the rubber-elastic material.

[0022] The object of the invention is achieved according to a second aspect of the invention by a rotary piston for a rotary piston pump, comprising a piston base structure, comprising o a hub structure with a bearing circumferential surface which extends around a rotational axis of the rotary piston, and o at least two piston vane structures connected to the hub structure, wherein the piston base structure is formed from a first, preferably metallic material and is preferably radially outwardly encased with a second material different from the first material, in particular an elastomer material, characterized in that the piston base structure is partially or completely produced in an additive manufacturing process, in particular a wire- or powder-assisted welding process,and o the at least two piston vane structures extend in the radial direction and are spaced apart from each other in the circumferential direction with respect to the axis of rotation, wherein the second material fills an undersize portion of the piston base structure and has an outer geometry that corresponds to a desired geometry of the rotary piston.,

[0023] According to this embodiment, the rotary piston has a basic piston structure that is manufactured using an additive manufacturing process and that has an undersize, i.e. an external geometry that does not correspond to the final desired external geometry of the rotary piston. This basic piston structure has at least two piston wing structures, preferably three, four or more piston wing structures, that are evenly distributed over the circumference of the rotary piston. It is preferably provided that each piston wing structure has a first cross-sectional area that lies in a first tangential plane to a first cylindrical surface around the axis of rotation and a second cross-sectional area that lies in a second tangential plane to a second cylindrical surface around the axis of rotation, wherein the second cylindrical surface lies radially outward from the first cylindrical surface and is smaller than the first cross-sectional area.The undersize cut and the preferably also formed cross-sectional area extension serve to accommodate the second material, which can be an elastomer material such as a rubber-elastic material, and allow it to adhere to the piston base structure in a particularly favorable manner. Firstly, the surface resulting from an additive manufacturing process is often already provided with such roughness, possibly also microgrooves due to a layer-by-layer or line-by-line manufacturing process in the additive process, thus achieving good adhesion and positive force transmission at the interface to the second material.Particularly in a welding deposition process, the line-like production in the form of the weld beads creates a surface macrostructure on the one hand, and the flaking along the weld bead creates a surface microstructure, which together are particularly advantageous for the subsequent coating of the surface because, on the one hand, the effective adhesion surface is increased and, on the other hand, a positive force transfer between the layer and the surface of the rotary piston is achieved. On the other hand, the cross-sectional area increase from radially inside to outside creates a beneficial undercut, which also increases the strength of the layer connection. The second material, which is applied to the basic piston structure, fills the difference to the target geometry of the rotary piston resulting from the undersize, so that the outer surface of the second material corresponds to the desired target geometry of the rotary piston.The rotary piston thus exhibits favorable mechanical properties, enables a geometrically free design of the outer geometry through the additive manufacturing process, and achieves improved adhesion of the second material, i.e., the elastomer coating, to the material of the piston base structure. As with the preceding embodiments of the invention, it should be understood that the piston base structure is preferably made of a metallic material, which is preferably possible, for example, using a build-up welding process.

[0024] In the previously explained rotary piston according to the first aspect of the invention, and also in the rotary piston according to the second aspect of the invention, it is preferably provided that the piston base structure is constructed in a radial construction direction with respect to the rotation axis in the additive manufacturing process. A radial construction direction here means that the rotary piston is constructed from layers, lines, or sections that are stacked one upon another in the radial direction. Additive manufacturing typically begins on a circumferential surface of a prefabricated hub structure, which thus serves as the cylindrical construction surface. This enables efficient production with resilient structures.

[0025] In the previously explained rotary piston according to the first aspect of the invention, and also in the rotary piston according to the second aspect of the invention, it is alternatively provided that the piston base structure is constructed in an axial construction direction with respect to the rotation axis in the additive manufacturing process. An axial construction direction is understood here to mean that the rotary piston is constructed from layers, lines, or sections that are stacked on top of one another in the axial direction. The construction direction of the layers orSections or lines therefore correspond to the direction of the rotational axis of the rotary piston. It should be understood that the buildup of the rotary piston can be achieved, for example, by applying material in the circumferential direction or in the radial direction, or a combination of these, in a layer plane. After the material buildup in this layer plane is completed, the buildup is continued in an overlying layer plane, which is then spaced apart in the axial direction, thereby determining the buildup direction. This axial buildup direction also results in a corresponding layering structure in the basic piston structure, which is formed by correspondingly recognizable interfaces between the individual layers, lines, or sections that delimit the axial layer layers of the rotary piston from one another.Thanks to the additive manufacturing process, these interfaces each exhibit sufficient strength so that the strength of the base material is not significantly reduced, for example, by fusion of one layer with the underlying layer. However, due to the corresponding material structures, the interfaces are visible, for example, microscopically in micrographs or on the outer surface of the rotary piston.

[0026] It is even further preferred if at least one preferably gas-filled cavity is formed in one, preferably each piston vane structure, which cavity is enclosed by a piston vane wall of the piston base structure and optionally by an outer peripheral surface of the hub structure and which is free of elastomer material, wherein the piston base structure preferably has an outer wall with an outer wall surface and an inner wall surface, and the cavity lies radially inward from the inner wall surface with respect to the axis of rotation, and further preferably the axis of rotation lies in the cavity. According to this embodiment, a cavity is formed in each piston vane of the rotary piston during the additive manufacturing process.This cavity can be closed or can be open toward the rotational axis of the rotary piston, so that the gas-filled cavities of the respective rotary piston vanes are formed by cavity sections of a possibly only single cavity, which extends into each piston vane in the manner of a bulge. It should be understood in principle that the rotary piston thus developed with a cavity in the piston vanes can be developed in the same way as previously explained for the rotary piston according to the first aspect of the invention.

[0027] The object of the invention is achieved according to a third aspect of the invention by a pump housing for a rotary piston pump, comprising a body base structure with an outer wall, which is produced in an additive selective application process, in which a material forming the outer wall is dispensed layer by layer along one or more paths via a multi-axis moving application head and thereby builds up the outer wall, wherein the outer wall is a curved wall with an outer wall surface and an inner wall surface, which has a surface mechanically produced in a machining process in the form of two intersecting partial cylindrical surfaces, which is produced by applying a machining allowance as a post-processing difference in the additive selective application process, so that the geometric dimensions exceed a target geometry of the inner wall surface,and by removing material to a thickness that compensates for the post-processing difference in a subsequent machining process, the surface of the inner wall surface is produced, wherein the body base structure further comprises a flange surface that has a flange surface that is mechanically produced in a machining process, which is produced by applying a machining allowance as a post-processing difference in the additive selective application process, so that the geometric dimensions exceed a target geometry of the flange surface, and by removing material to a thickness that compensates for the post-processing difference in a subsequent machining process, the flange surface is produced, wherein preferably the application head is moved along path sections that are transverse to the inner wall surface of the wall,in particular, at an angle of 50° - 90° to the inner wall surface. According to this embodiment, the pump housing for a rotary lobe pump is manufactured using an additive manufacturing process. The pump housing, with its internal geometry defined by the inner wall surface, is manufactured in such a way that a machining allowance is built up in the additive manufacturing process, which is then removed again in a subsequent mechanical machining process in order to thereby produce a precise geometry of the inner wall surface, which has a high surface quality and is therefore suitable for the sealing interaction with the rotary lobes running therein. It should be understood that this housing according to the third aspect of the invention preferably cooperates with a rotary lobe according to the first or second aspect of the invention. According to the invention, the basic body structure further comprises a flange surface,which also has a machining allowance that is removed in a mechanical machining process following the additive manufacturing process, in order to thereby produce a flange surface designed for connection to a gear housing, a drive housing, or for connecting a cover, or for connecting an inlet pipe or an outlet pipe. Accordingly, the pump housing can also have several such flange surfaces, for example, four flange surfaces, which are provided for the above-mentioned connections. It should be understood that the flange for connecting a drive or gear housing, as well as the flange for connecting a front cover, typically encloses the two axes of rotation defined by the central longitudinal axes of the two partial cylindrical surfaces.whereas the two flange surfaces for the inlet and outlet enclose the corresponding inlet opening and outlet opening, respectively, and are located radially outwardly of these two axes of rotation, so that the cross-sectional areas defined by these flange surfaces and corresponding to the inlet opening and outlet opening, respectively, are preferably parallel to the axes of rotation of the rotary pistons defined by the central longitudinal axes of the partial cylinder surfaces. In particular, it is preferred if these flange surfaces of the inlet opening and the outlet opening each lie in a plane parallel to a plane in which the two central longitudinal axes of the partial cylinder surfaces lie.

[0028] The invention is also directed to a rotary lobe pump having a housing of the type described above and / or having a rotary lobe according to the first or second aspect of the invention.

[0029] The object of the invention is further achieved by a rotor for an eccentric screw pump, comprising: a rotor base structure, comprising o a hub structure with a bearing circumferential surface which extends around a longitudinal axis of rotation of the rotor, and o a threaded structure connected to the hub structure, which extends along the longitudinal axis of rotation and which has an ■ outer wall surface which has a threaded structure wound around the longitudinal axis of rotation, and

[0030] ■ has an inner wall surface which encloses a preferably gas-filled cavity, characterized in that the rotor base structure is produced partially or completely in an additive manufacturing process, in particular a wire- or powder-supported welding process, and the thread structure is formed by a curved wall with a substantially constant wall thickness, whereby the inner wall surface extends substantially congruently radially inward with respect to the longitudinal axis of rotation from the outer wall surface and the axis of rotation extends in the cavity.

[0031] According to this embodiment, a rotor for an eccentric screw pump is manufactured using an additive manufacturing process. This aspect of the invention, like the previously explained rotary piston according to the first and second aspects of the invention, is therefore directed to a displacement body of a positive displacement pump. The rotor has an outer wall surface that has a thread structure. In a rotor for an eccentric screw pump, this thread structure is typically realized by a rounded, single-start, double-start, or multi-start external thread geometry, which can rotate and roll in an eccentric rotational movement in a stator that has a correspondingly adapted internal thread geometry that has one more thread turn than the rotor running therein.This allows axial flow through the stator along the stator's longitudinal axis to be achieved, with the inflow into the stator and the outflow out of the stator preferably being in the axial direction without a radial directional component. The rotor according to the invention is characterized by a substantially uniform wall thickness, whereby a cavity is formed inside the rotor which contains the rotor's longitudinal axis of rotation and is delimited radially outwards by the inner wall surface of the rotor base structure. This inner wall surface runs substantially congruently, i.e. approximately parallel to the outer wall surface of the rotor. It should be understood that additional structures, such as ribbing or other reinforcements, can be arranged and applied, in particular, to the inner wall surface in order to impart greater strength and rigidity to the rotor, provided this is required for the application.

[0032] By designing the rotor in this way, a particularly lightweight rotor is created, yet at the same time, thanks to the thread-shaped design of the inner and outer wall surfaces, it is very rigid. Furthermore, thanks to the additive manufacturing process, the rotor can be designed in a variety of ways with regard to its outer wall geometry. For example, a conically tapered rotor can be produced, or a rotor with a thread depth that varies along the longitudinal axis, allowing the rotor to be moved with an increasing or decreasing eccentricity in the stator along the longitudinal axis.

[0033] It is particularly preferred if the rotor base structure is made of a metallic material and has a surface that is formed by producing the outer wall surface with a machining allowance in the additive manufacturing process, which is subsequently removed by a machining process down to an outer geometry that corresponds to a target geometry of the rotor. According to this further development, a machining allowance is applied to the outer wall surface and removed by a machining process in a subsequent processing step in order to produce the target geometry of the rotor. This removal in a machining process can take place in an indeterminate manner, for example by grinding with sandpaper, in order to achieve minimal material removal and an improvement in surface quality with a reduction in roughness.The machining process can also be performed using a CNC-controlled machining tool, such as a multi-axis grinding or milling tool, or a whirling tool to remove the machining allowance. In this case, the machining process can also precisely define the geometry of the outer wall surface.

[0034] It should be understood that the rotor according to the invention can also be provided with end faces or flange surfaces at its end. These end faces or flange surfaces can be placed as prefabricated surfaces on the additively manufactured rotor base structure and connected to it, for example, by welding. Alternatively, the end faces or flange surfaces can also be formed using the additive manufacturing process. The end faces or flange surfaces can partially or completely close the cavity of the rotor, so that fluid pumped in the eccentric screw pump cannot penetrate into this cavity. Such an end face or flange surface then also serves to connect the rotor to a drive device, for example, as a flange for connecting the rotor to a wobble shaft.Finally, the object of the invention is also achieved according to a fifth aspect of the invention by a stator for an eccentric screw pump, comprising: a stator base structure which extends along a stator longitudinal axis and o has an inner wall surface which winds around the stator longitudinal axis.

[0035] Has thread geometry and encloses a preferably gas-filled cavity in which the stator longitudinal axis runs, and o Has an outer wall surface, wherein the stator basic structure is formed by a curved wall with a substantially constant wall thickness, whereby the outer wall surface runs substantially congruently radially outwards with respect to the stator longitudinal axis from the inner wall surface.

[0036] A stator for an eccentric screw pump, as previously explained in connection with the rotor, has an inner wall surface with a thread geometry winding around the stator's longitudinal axis. In all-metal stators, this inner wall surface can also form the direct contact surface with the rotor, which moves in an eccentrically guided rotational movement within the cavity enclosed by the inner wall surface. In such a case, it is advantageous if the inner wall surface is machined using a machining process in order to bring it to the desired geometry. A high surface quality can be achieved through such a machining process. Typically, however, the inner wall surface of a stator is coated with a rubber-elastic material layer, and the inner surface of this elastomer layer then defines the desired inner geometry of the stator and is in contact with the rotor.In this case, the basic stator structure is designed with an undersize reduction, i.e. it has diameter dimensions that are larger than the desired internal geometry of the stator and this undersize reduction is filled by the elastomer material when coating the inner wall surface up to the desired nominal dimension.

[0037] The stator according to the invention has an outer wall surface that extends essentially congruently radially outward to the inner wall surface, i.e., is essentially parallel to this inner wall surface. As a result, the stator according to the invention can be formed with a wall of essentially constant wall thickness, which enables a stator base structure with significantly reduced weight and, at the same time, favorable rigidity. The stator can preferably be designed in one piece, and a construction of the stator from several annular segments can therefore be dispensed with. It is particularly preferred if the stator base structure is formed from a metallic material. For a metallic material, various preferred manufacturing methods are available for the stator base structure, for example casting processes and additive manufacturing processes with which metallic materials are processed.A metallic material can also be easily reworked using a machining process, for example to produce a better surface quality.

[0038] It is particularly preferred if the stator base structure is manufactured partially or completely using an additive manufacturing process, in particular a wire- or powder-assisted welding deposition process. Manufacturing the stator base structure using an additive manufacturing process allows, on the one hand, the formation of the stator with congruent inner and outer wall surfaces in a particularly efficient manner. On the other hand, the specific thread structure with a two- or multi-start internal thread can also be manufactured economically using an additive manufacturing process. A wire- or powder-assisted welding deposition process is particularly suitable for manufacturing the stator base structure.In this process, a wire or supplied powder is melted in an arc ignited between the wire and the partially manufactured stator base structure, or ignited between a separate electrode and the partially manufactured stator base structure. This melting process selectively adds the wire or powder material to the partially manufactured stator base structure and firmly bonds it to it. Consequently, this type of welding deposition process allows a stator base structure to be manufactured selectively, precisely, and quickly.

[0039] It is even more preferred if the wall of the stator base structure comprises a metallic wall layer and a layer of an elastomer material, wherein the metallic wall layer has an inner undersize cutout, which is filled with the elastomer material in a subsequent application process, forming the desired geometry of the inner wall surface. According to this embodiment, the stator base structure is formed and prepared to be coated on its inner wall surface with an elastomer material, as is typically done for stators of eccentric screw pumps. For this purpose, the inner wall surface to which the elastomer material is applied has an undersize cutout, which means that this inner wall surface has a larger diameter than the desired desired geometry of the inner wall surface of the finished stator.This target geometry is only achieved by coating with the elastomer material and the inner target geometry of the stator is then formed by the inner wall surface of this elastomer material coating.

[0040] The invention further comprises an eccentric screw pump which is equipped with a rotor of the type described above, which is arranged parallel and eccentrically to a stator longitudinal axis of a stator.

[0041] Furthermore, the invention includes an eccentric screw pump with a stator of the previously described design, wherein a rotor is arranged within the stator and parallel and eccentrically to the stator longitudinal axis.

[0042] Finally, the invention further encompasses an eccentric screw pump comprising both a rotor of the previously described design and a stator of the previously described design. This eccentric screw pump designed in this way particularly advantageously allows the stator and rotor to be manufactured using an additive manufacturing process, providing appropriate machining allowances or machining allowances depending on whether a subsequent coating is required or whether subsequent material removal is required using a machining process.

[0043] The invention is further directed to a use of an additive manufacturing device, in particular a wire- or powder-supported welding application device, for producing a piston base structure of a rotary piston of a rotary piston pump on a prefabricated hub with a build-up direction in the additive manufacturing device that runs radially outward with respect to a rotational axis of the hub, or producing a piston base structure of a rotary piston of a rotary piston pump on a substrate plate with a build-up direction in the additive manufacturing device that runs axially with respect to a rotational axis of the rotary piston, or producing a stator base structure of a stator of an eccentric screw pump with a build-up direction in the additive manufacturing device that runs axially with respect to a rotational axis of the rotary piston, in particular in such a way that a wall is produced in the additive manufacturing device,which encloses a preferably gas-filled cavity, and / or a wall is produced in the additive manufacturing device which has a machining allowance compared to a target geometry and the machining allowance is removed after the additive manufacturing in a machining device so that the surface of the piston base structure is reduced to a target size, and / or a wall is produced in the additive manufacturing device which has an undersize reduction compared to a target geometry and the undersize reduction is filled with an elastomer material up to the target geometry after the additive manufacturing in a coating device,so that the piston base structure is covered with an elastomer material or the stator base structure is lined with an elastomer material. This application proposes the specific use of an additive manufacturing device for producing a rotary piston of a rotary piston pump or a stator of an eccentric screw pump, i.e. those components of a positive displacement pump that typically consist of two different materials, namely a material for the base structure, typically a metallic material, and an elastomer coating, typically a rubber-elastic material. According to the invention, the additive manufacturing device is used in such a way that, with regard to the rotary piston produced thereby, the construction direction is either radial,i.e., extending radially outward from a prefabricated hub structure and consequently producing corresponding radially stacked layers of the rotary piston, or the assembly direction is axial, i.e., extending along the rotational axis of the rotary piston and consequently also producing stacked layers of the rotary piston in the direction of the rotational axis. In this second case, the hub of the rotary piston can be produced in the additive manufacturing device. For example, in addition to the rotary piston vane structures, the rotary piston can also have end-side hub receiving structures in the form of end or flange surfaces, into which a hub can be subsequently inserted to accommodate the rotary piston on or at a shaft. As previously explained in connection with the rotor,Such a front or flange surface can be placed as a prefabricated plate or component onto the additively manufactured piston base structure and connected to it, for example, by welding. However, a hub structure can also be produced integrally with the rotary piston vane structures using the additive manufacturing process.

[0044] According to the invention, in a first alternative, a wall is produced in the additive manufacturing device that encloses a preferably gas-filled cavity. Such a cavity can, for example, be formed in a rotary piston vane structure, as explained above, or can be formed inside a rotary piston or a stator, so that the rotary piston or stator is designed as a hollow structure. In this case, the cavity is not necessarily completely closed; rather, openings can be formed in the cavity, which, for example, serve to accommodate the rotor in the stator or to accommodate a hub or a drive shaft in the rotary piston.

[0045] Alternatively or additionally, a wall with a machining allowance can also be produced in the additive manufacturing device. Such a machining allowance is formed by an additional portion of material that extends beyond the target geometry of the rotary piston or stator and can be removed in a subsequent machining process to achieve a particularly high surface quality and geometric precision, for example, to provide connection surfaces for other components, sealing surfaces, and bearing surfaces of the rotary piston and stator.

[0046] Furthermore, it is alternatively or additionally provided that a wall is produced in the additive manufacturing device which has an undersize reduction. An undersize reduction is to be understood in the sense of the invention as a material portion missing from the target geometry, which is filled in a later processing step in order to achieve the target geometry. Typically, such an undersize reduction is provided in order to be able to provide an elastomer coating, for example made of a rubber-elastic material, and in this design, the rough surface typically produced by the additive manufacturing process is advantageously used to achieve particularly good adhesion and, in some cases, a form-fitting fastening effect of the elastomer layer to the additively manufactured surface of the structure.In other applications, however, the undersize can also be filled with other materials to the target size, for example, to apply corrosion-protective or wear-resistant coatings, or to apply a layer in a subsequent process that achieves a particularly high surface quality with low roughness or particularly high geometric precision. For example, an undersize can also be filled in a subsequent additive manufacturing process using additive selective material deposition.

[0047] The invention further comprises a use of an additive manufacturing device, in particular a wire- or powder-supported welding application device, for producing a pump housing base structure of a rotary lobe pump, wherein the pump housing base structure has a wall with intersecting, partially cylindrical wall inner surfaces arranged around two axes of rotation within a pump chamber, on a substrate plate with a construction direction in the additive manufacturing device that runs axially with respect to the two axes of rotation, or production of a rotor base structure of a rotor of an eccentric screw pump, wherein the rotor base structure has a wall with an outer wall surface winding around a rotation axis in a thread geometry, on a substrate plate with a construction direction in the additive manufacturing device that runs axially with respect to the rotation axis of the rotor, in particular in such a way,that the inner wall surface of the wall produced in the additive manufacturing device encloses a cavity and the wall thickness of the wall is substantially constant along the entire length of the wall, so that the outer wall surface runs substantially parallel to the inner wall surface, and / or a machining allowance is produced on the inner wall surface or the outer wall surface in the additive manufacturing device, and after the additive manufacturing, the pump housing base structure produced therein or the rotor base structure produced therein is remachined in a machining device in order to remove the machining allowance and thereby form a desired inner geometry of a pump housing and a desired geometry of a pump housing flange from the pump housing base structure, or to form a thread-shaped desired outer geometry of a rotor from the rotor base structure.

[0048] According to this inventive use, an additive manufacturing device is used in a specific manner to produce a pump housing of a rotary lobe pump or a rotor of an eccentric screw pump. This use is therefore directed to the production of those components of positive displacement pumps that typically do not receive an elastomer coating, but are regularly made of a metallic material. The manufacturing device is used in a specific manner such that, according to an alternative application, a wall is produced that has an inner wall surface. This inner wall surface encloses a cavity, and the wall thickness of the wall is essentially constant over the entire length of the wall.A substantially consistent profile means that the geometric shape of the outer wall is at least partially reflected congruently on the inner wall surface, preferably with the outer wall and the inner wall surface running parallel to one another. This type of application results in a particularly lightweight yet rigid structure for the rotary piston housing or rotor. At the same time, the material consumption for manufacturing the rotary piston housing or rotor is significantly reduced. This is achieved, on the one hand, by the specific geometry with a wall of consistent wall thickness, and, on the other hand, by the additive manufacturing process in the manufacturing device, which fundamentally reduces or even completely eliminates material loss due to machining.

[0049] Alternatively or additionally, the pump housing base structure or rotor base structure can be manufactured in the additive manufacturing device with a machining allowance on the inner wall surface or the outer wall surface in order to be able to produce the desired target geometry with high surface quality and high geometric precision by subsequent removal of material, as explained above. Reference is made to the above explanation of the machining allowance, and it should be understood that the machining allowance can be used, for example, to produce a flange surface for a drive housing or a cover of the pump housing, to produce the inner wall surface of the pump housing that is in sealing contact with the rotary pistons, to produce a flange connection surface for a drive shaft or a bearing surface or sealing surface on the rotor, or to produce the external thread geometry of the rotor.

[0050] The invention further relates to a method for producing a displacement body or a housing of a displacement pump, such as a rotary piston or pump housing for a rotary piston pump or a rotor or stator for an eccentric screw pump, comprising the steps:

[0051] Providing a construction area

[0052] Building a basic body structure on the build-up surface in an additive manufacturing process, in particular a wire- or powder-assisted welding deposition process, characterized in that the building of the basic body structure comprises the step of building a curved wall of a displacer or housing structure on the build-up surface and enclosing a gas-filled cavity with the curved wall.

[0053] The method according to the invention is characterized in that a displacement body or a housing of a positive displacement pump is manufactured using an additive manufacturing process, and a curved wall, which forms a displacement structure or a housing structure, is built up on a construction surface and encloses a cavity. As explained above, the curved wall can preferably have a substantially constant wall thickness. The gas-filled cavity can be a completely closed cavity, in which the gas is consequently enclosed during the additive manufacturing process and subsequently remains in the cavity. The cavity can also be an incompletely closed cavity, for example an interior space of a housing or stator. Multiple gas-filled cavities can also be provided.For example, closed, gas-filled cavities can be provided in each rotary piston vane of a rotary piston, or gas-filled cavities can be provided in the wall of a housing to create a rigid yet lightweight structure with low material consumption and to potentially use these cavities for fluid flow during subsequent operation for cooling or heating a fluid pumped by the positive displacement pump. The cavity can preferably be completely enclosed, or more than half of its inner surface, by the wall produced using the additive manufacturing process.

[0054] It is particularly preferred if the body base structure is produced in the additive manufacturing process, in particular a wire- or powder-assisted welding deposition process, wherein the body base structure has a prefabrication surface which, with a post-processing difference, which is a machining allowance or an undersize reduction, corresponds to a desired geometry of the displacement body of the displacement pump, and the prefabrication surface is post-processed by adding or removing material to a thickness that compensates for the post-processing difference, preferably further comprising a first post-processing step in which the machining allowance on the circumferential surface is removed to a desired dimension in a machining process, and / or preferably further comprising a second post-processing step in which the prefabrication outer surface of the displacement structure is coated with a layer of an elastomer material,which fills the undersize and has an outer geometry that corresponds to a target outer geometry of the rotary piston or a target inner geometry of the stator. With this embodiment, the displacer body or the housing is built up in the additive manufacturing process in the axial direction, i.e., along the direction of a rotational axis defined by the displacer body or the housing. The build-up can be carried out line-by-line or layer-by-layer, with the lines being drawn, for example, in a welding deposition process, and the material layer created by this line deposition then representing a deposition layer. The material layers produced in this way are stacked on top of one another in the axial direction. The guidance of an application device or a curing device is typically multi-axial in the additive manufacturing process.To selectively produce or harden a cross-sectional area corresponding to the cross-section of the manufactured body in one plane, and subsequently to harden or apply a material portion corresponding to the cross-section of the manufactured body in this cross-sectional area in a cross-sectional area lying thereon. The position of these cross-sectional areas therefore corresponds to the layer position, and the plane of these cross-sectional areas is therefore perpendicular to the construction direction or the rotation axis of the displacer body or the housing.

[0055] It is even more preferred if the body base structure is manufactured in the additive manufacturing process, in particular a wire- or powder-assisted welding deposition process, wherein the body base structure has a prefabrication surface which, with a post-processing difference, which is a machining allowance or an undersize reduction, corresponds to a desired geometry of the displacement body of the displacement pump, and the prefabrication surface is post-processed by adding or removing material to a thickness that compensates for the post-processing difference, preferably further comprising a first post-processing step in which the machining allowance on the peripheral surface is removed to a desired dimension in a machining process, and / or preferably further comprising a second post-processing step in which the prefabrication outer surface of the displacement structure is coated with a layer of an elastomer material,which fills the undersize allowance and has an outer geometry that corresponds to a target outer geometry of the rotary piston or a target inner geometry of the stator. According to this embodiment, the additive manufacturing process produces a basic body structure that has a geometry that is built with a post-processing difference as the outer or inner geometry. Such a post-processing difference can be a machining allowance or an undersize allowance and can be used to subsequently remove or add material in a subsequent machining step in order to thereby produce the target geometry. Reference is made to the above explanation of the machining allowance and undersize allowance.

[0056] The method according to the invention can preferably be used for producing a rotary piston or a stator, wherein the body base structure has a hub or flange structure with a circumferential surface that runs rotationally symmetrically around a rotational axis of the displacement body and that has a machining allowance, and a displacement structure, wherein the displacement structure has at least two displacement structures formed radially inward or outward from the hub structure, which extend in the radial direction with respect to the rotational axis and are spaced from one another in the circumferential direction and which have an undersize reduction on their prefabrication outer surface as a post-processing difference, wherein the post-processing comprises a first step in which the machining allowance on the circumferential surface is removed to a desired dimension in a machining process, and the post-processing comprises a second step,in which the prefabricated outer surface of the displacer structure is coated with a layer of an elastomer material that fills the undersize and has an outer geometry that corresponds to a target outer geometry of the rotary piston or a target inner geometry of the stator.

[0057] According to this development, the method is used to produce a component of a positive displacement pump which is to receive both a subsequent coating with a second material such as an elastomer layer, and a connection, sealing or bearing surface which is to serve for a geometrically precise connection or seal or bearing of the rotary piston or stator to another component of the positive displacement pump. According to the invention, the additive manufacturing process is carried out in such a way that a machining allowance is produced on a surface produced in the process, which can therefore be removed in a subsequent machining process in order to thereby have the surface quality and geometric precision required for precise bearing / sealing or connection.In another area of ​​surfaces produced using the additive manufacturing process, however, an undersize offset is created, which is then filled with a second material, such as a rubber-elastic material, in a subsequent manufacturing step to match the target geometry of the rotary piston or stator. This allows the rubber-elastic coating desired for a rotary piston or stator to be efficiently and reliably bonded to the base structure in an adhesive and, in some cases, form-fitting manner due to the favorable surface roughness from the additive manufacturing process. The process therefore comprises two post-processing steps in which this removal of the machining allowance or this filling of the undersize offset is carried out.

[0058] It is further preferred if the construction of the body base structure comprises the step of: constructing a body base structure with at least two piston wing structures and enclosing a gas-filled cavity in each piston wing structure with the curved wall, wherein the cavity remains free of elastomer material during any subsequent coating.

[0059] According to this development, during the production of the basic body structure of a rotary piston, a preferably gas-filled cavity is enclosed by the wall produced using the additive manufacturing process, and this gas-filled cavity remains free of elastomer material in any subsequent coating process. With this development, a rotary piston can be produced which is particularly lightweight due to the gas-filled cavity contained therein, but without accepting any significant loss of strength or rigidity. It is to be understood that such a cavity, which is each closed in itself, can preferably be present in each piston wing structure. In certain embodiments, each piston wing structure can also have a cavity, and the cavities of the piston wing structures are interconnected.

[0060] According to a further preferred embodiment, the method is further developed in that, when constructing the basic body structure, at least two piston wing structures are constructed which are arranged at an angle to one another in the circumferential direction around the axis of rotation, and wherein each piston wing structure has an enveloping contour which, starting from a piston wing root which is arranged adjacent to the circumferential surface and has a root width in the circumferential direction around the axis of rotation, extends in the radial direction to a piston wing head which has a head width in the circumferential direction around the axis of rotation, wherein the enveloping contour between the piston wing root and the piston wing head has a piston wing neck which has a neck width in the circumferential direction around the axis of rotation which is less than the root width and which is preferably less than the head width.According to this embodiment, the rotary piston has two piston vane structures, which are divided into a piston vane head, a piston vane base, and a piston vane neck located therebetween. As previously explained, the three sections each occupy approximately 1 / 3 of the radial height of the piston vane. The piston vane neck represents a constriction in the circumferential direction relative to the piston vane base, and the circumferential width in the region of the piston vane neck is preferably also smaller than the width at the piston vane head, resulting in an hourglass shape of the piston vane structure in cross-section perpendicular to the rotation axis of the rotary piston.This shape is advantageous for rolling the piston vanes of two intermeshing rotary pistons on each other and according to this preferred embodiment, the basic piston structure already defines this shape of the rotary piston and therefore ensures a coating that is applied, if necessary, in a uniform layer thickness to achieve the desired geometry of the rotary piston.It is even more preferred if, during construction of the basic body structure, a preferably gas-filled cavity is enclosed in each piston wing structure, which cavity extends from the piston wing root, which is arranged adjacent to the circumferential surface and has a root cavity width in the circumferential direction around the rotation axis, in the radial direction to the piston wing head, which has a head cavity width in the circumferential direction around the rotation axis, and the cavity between the piston wing root and the piston wing head has a neck cavity width in the circumferential direction around the rotation axis that is smaller than the foot cavity width and which is preferably smaller than the head cavity width. According to this embodiment, a cavity is formed inside the piston wing, which has a smaller width in the circumferential direction in the piston wing neck than in the piston wing root and preferably also a smaller width than in the piston wing head.The cavity can therefore follow a corresponding outer geometry of the piston wing, so that a substantially uniform wall thickness can be formed in the area of ​​the piston wing and at the same time a cavity with maximized volume is created, which implements the advantages of weight and material savings in the best possible way without significantly impairing the stiffness and strength of the piston wing.

[0061] The method can be further developed in that the basic body structure comprises at least one displacement structure, in particular two piston vane structures, and each displacement structure has a wall that preferably encloses a cavity, in particular a gas-filled cavity, and has a plurality of external structural ribs that are built up on the wall in the additive manufacturing process. The structural ribs are preferably located in a post-processing difference designed as an undersize reduction. According to this embodiment, structural ribs are formed on the outer wall of the piston vane structures, which can also be manufactured integrally in the additive manufacturing process.These ribs serve to improve the bond to an elastomer layer applied to the rotary piston and to increase the resistance to shear forces that exist at the interface between this elastomer layer and the basic piston vane structure by enabling positive support of the elastomer layer on the ribs. The ribs are preferably located in a post-processing difference, which is designed as an undersize reduction. This means that the ribs define an envelope, the outer contour of the piston vane is laid out including the ribs, and this envelope is located at a distance from the nominal geometry of the piston that defines the undersize reduction.This ensures that the applied elastomer layer has a layer thickness at least corresponding to the undersize reduction and therefore a desired degree of deformation of the elastomer layer is guaranteed in all areas of this layer.

[0062] It is further preferred if the structural ribs comprise a group of circumferential ribs that extend substantially along the circumferential direction across the wall and that preferably run parallel to one another and / or if the structural ribs comprise one or more axial ribs that extend substantially along the axial direction with respect to the axis of rotation and / or if the structural ribs comprise one or more axial-radial ribs that extend substantially along the circumferential longitudinal direction of a blade, in particular extend helically along a blade running with a pitch around the axis of rotation. According to this embodiment, circumferential ribs, axial ribs and / or axial-radial ribs are formed, which preferably lie in the post-processing difference formed as an undersize reduction and consequently define a minimum thickness of the elastomer layer.The circumferential ribs can preferably intersect the axial ribs, with the axial ribs running in the axial direction intersecting the circumferential ribs running in the circumferential direction. Such intersections significantly increase the rigidity of the rotary piston and improve the attachment of the elastomer layer to the basic body structure of the rotary piston. If a rotary piston is used that has piston vanes that extend helically around the axis of rotation, the ribs can also extend as axial-radial ribs along the outer wall of such a wound vane, which corresponds to a helical course around the axis of rotation of the piston.

[0063] The invention is further directed to a method for producing a displacement body or a housing of a displacement pump, such as a rotary piston or pump housing for a rotary piston pump or a rotor or stator for an eccentric screw pump, comprising the steps:

[0064] Providing a construction area,

[0065] Building a body base structure on the construction surface, wherein the body base structure has a prefabricated outer surface which corresponds to an outer geometry of the displacer body with a post-processing difference, which is a machining allowance or an undersize reduction, post-processing the prefabricated outer surface by adding or removing material in a thickness that compensates for the post-processing difference, characterized in that the body base structure is manufactured in an additive manufacturing process, in particular a wire- or powder-assisted welding deposition process, and the body base structure has a hub structure with a flange surface which is rotationally symmetrical about a rotation axis of the displacer body and which has a machining allowance, wherein the post-processing comprises a first step,in which the machining allowance on the flange surface is removed to a nominal dimension in a machining process, and has a displacement structure which winds around the axis of rotation and which has a radial machining allowance on its prefabrication outer surface as a post-processing difference, wherein the post-processing comprises a second step in which the machining allowance on the prefabrication outer surface is removed to a nominal dimension in a machining process, or has a displacement structure which winds around the axis of rotation and which has a radial undersize reduction on its prefabrication outer surface as a post-processing difference, wherein the post-processing comprises a second step in which the undersize reduction on the prefabrication outer surface is filled to a nominal dimension in a coating process.

[0066] According to the method according to the invention thus defined, a displacement body or a housing of a positive displacement pump is manufactured using an additive manufacturing process, and a post-processing difference during production using the additive manufacturing process is taken into account, which is a machining allowance or an undersize allowance. This machining allowance is used for post-processing in a machining process in order to achieve sufficient surface quality and geometric precision relative to the target geometry, for example, on a flange surface used for sealing, bearing, or connecting to other components of the positive displacement pump. The machining allowance can also be provided on a displacement structure of the displacement body or the housing.In the sense of the invention, such a displacement structure is understood to be a surface of the displacement body or the housing that is in contact with the fluid to be pumped and provides a sealing effect for the pumping of this fluid, i.e., a structure with a surface that is in moving, sealing contact between the displacement body and the housing. Consequently, the displacement structure is understood to be the piston vanes of a rotary piston, the threaded structure of a rotor, the groove structure of a stator, and the inner surface of a housing of a rotary lobe pump that defines the pump chamber.According to the invention, either a machining allowance or an undersize allowance can be provided on such a displacer structure, which in the first case enables machining to produce a high surface quality and geometric precision and in the second case enables coating with a second material such as an elastomer material, for example to produce a rotary piston coated with a rubber-elastic layer or a stator lined with a rubber-elastic layer.

[0067] For the production of a rotary lobe, a stator, or a rotor, it is preferred if the displacement structure is preferably thread-shaped and has a thread depth in the radial direction with respect to the axis of rotation. Such a thread-shaped design enables the operation of a rotor and stator of an eccentric screw pump and enables pulsation-reduced or pulsation-free conveying with a rotary lobe pump. A thread-shaped displacement structure is understood to mean a displacement structure that is designed like a thread with one or more thread turns with intermediate thread valleys that wind helically around a rotation axis.In the case of a rotor or stator, the thread typically runs at a pitch angle of more than 60°, defined as the angle between the direction along which a thread pitch extends in a developed view and the base line, which lies in a cross-sectional area perpendicular to the rotation axis. The thread can, in particular, be multi-start.

[0068] The method can be further developed by constructing the basic body structure by constructing the displacement structure as a curved wall on the construction surface and enclosing a gas-filled cavity with the curved wall. Enclosing a gas-filled cavity, which can be designed as previously described, enables a weight- and material-saving design of the basic body structure.

[0069] It is even further preferred if the method is further developed in which the construction surface is a surface of a substrate plate, and the body base structure is built up layer by layer in the direction of the axis of rotation of the displacer body or the housing on the surface of the substrate plate, with the axis of rotation being perpendicular to the surface of the substrate plate. According to this further development, the body base structure is built up perpendicularly on a construction plate serving as a substrate plate, so that the length of the body base structure that can be achieved along the axis of rotation is not limited by the dimensions of the substrate plate, but rather by the overall height available above the substrate plate in the additive manufacturing device. This construction method enables the production of body base structures with a sufficient length for the inventive production of, for example, rotors or stators for eccentric screw pumps.The layering of the material applied layer by layer or line, achieved in this manufacturing method, consequently has layer boundaries between two adjacent layers that are approximately perpendicular to the rotation axis, i.e. approximately parallel to the cross-sectional area around the rotation axis.

[0070] It is even further preferred if a build-up production data set for controlling the construction of the body basic structure in an additive manufacturing process is generated from geometric target data of the displacer body or housing and the construction of the body basic structure is controlled using this build-up production data set, and a removal production data set is created from the geometric target data and / or the build-up production data set and the post-processing is carried out by a multi-axis milling operation which is controlled using the removal production data set.According to this embodiment, a data set is created from the geometric target data of the displacer body or the housing, which serves to control the sequence of the additive manufacturing process in the additive manufacturing device. Based on the data set thus created for the assembly production in the additive manufacturing process or based on the geometric target data, a second data set is created. This second data set is designed for removal production and represents a CAD / CAM data set with which the subsequent removal of machining allowances takes place. Through this direct derivation of the production control data for the additive manufacturing process on the one hand and the machining removal process on the other, a high geometric precision of production is achieved in the additive manufacturing process and the machining removal process.At the same time, it makes it possible to keep the machining allowance as low as possible to minimize the volume to be machined, without the risk of the machining allowance falling below the target value in one area of ​​the geometry, thus making subsequent machining impossible. The creation of the manufacturing data defined in this training further reduces the computing effort and storage volume required to generate the required manufacturing data sets for the successive manufacturing steps of additive manufacturing and machining.

[0071] It is particularly preferred if the method is used to produce a stator of an eccentric screw pump, that the method proceeds with the steps: providing a mounting surface, building a body base structure on the mounting surface, wherein the body base structure has a prefabricated outer surface which corresponds to an outer geometry of the stator with a post-processing difference, which is a machining allowance or an undersize reduction, post-processing the prefabricated outer surface by depositing or removing material in a thickness that compensates for the post-processing difference, characterized in that the body base structure is produced in an additive manufacturing process, in particular a wire- or powder-assisted welding process, and the body base structure comprises a curved wall with an inner wall surface and an outer wall surface, which extends in the axial direction with respect to the axis of rotation,wherein the inner wall surface surrounds the rotational axis and has at least two threads that wind around the rotational axis, the inner wall surface has an undersize allowance as a remachining difference, and the prefabrication outer surface comprises a prepared flange surface that has a machining allowance as a remachining difference, the remachining comprises a first step in which the machining allowance on the prepared flange surface is removed to a desired dimension in a machining process, thereby producing a flange surface, and the remachining comprises a second step in which the prefabrication outer surface of the piston vane structures is coated with a layer of an elastomer material that fills the undersize allowance and has an outer geometry that corresponds to a desired geometry of the rotary piston.

[0072] Furthermore, when the method is used to manufacture a pump housing of a rotary lobe pump, it is particularly preferred if the method comprises the following steps: providing a mounting surface that is perpendicular to a rotational axis, constructing a body base structure on the mounting surface, wherein the body base structure has a prefabrication flange surface and a prefabrication inner wall surface, which corresponds to a flange surface and an inner wall surface of the pump housing with a post-processing difference, post-processing the prefabrication flange surface and the prefabrication inner wall surface by removing material to a thickness that compensates for the post-processing difference, characterized in that the body base structure is manufactured in an additive manufacturing process, in particular a wire- or powder-assisted welding process, and the body base structure,a curved wall with the prefabrication inner wall surface and an outer wall surface extending in the axial direction with respect to the rotation axis, wherein the prefabrication inner wall surface surrounds the rotation axis and has two intersecting partial cylindrical surfaces, the post-machining comprises a first step in which the machining allowance on the prefabrication flange surface is removed to a desired dimension in a machining process, thereby producing a flange surface, and the post-machining comprises a second step in which the machining allowance on the prefabrication inner wall surface is removed to a desired dimension in a machining process, thereby producing an inner wall surface.

[0073] According to this embodiment, it is particularly provided that the body base structure, in particular the displacement body, the stator or the pump housing, extends along a production rotation axis, the provision of a construction surface comprises providing a substrate plate with a surface forming the construction surface, the construction of the body base structure comprises building the body base structure on the surface, wherein the surface is oriented horizontally and the body base structure is built up layer by layer in a vertically oriented construction direction thereon, wherein the construction direction runs parallel to the production rotation axis and layers of the layered body base structure lie approximately perpendicular to the production rotation axis.

[0074] According to a further preferred embodiment, the method is further developed in which the wall is constructed as a double wall with an inner wall having the inner wall surface and an outer wall having the outer wall surface, and at least one preferably gas-filled cavity is formed between the inner wall and the outer wall. By configuring the wall as a double wall in this way, stiffening is achieved on the one hand, and weight- and material-saving production is achieved on the other. The cavity can remain as a cavity during later operation of the component and consequently bring about a weight reduction of the component. In another application, the cavity can serve to conduct a fluid such as a cooling or heating liquid in order to produce a cooling or heating effect on the positive displacement pump.

[0075] Furthermore, it is particularly preferred in all embodiments of the method according to the invention that produce a preferably gas-filled cavity during the additive manufacturing process if, during construction of the basic body structure, one or more ribs are constructed that extend through the cavity to stiffen a wall structure around the cavity, wherein preferably each cavity is stiffened by one or more ribs. Such ribs can divide the cavity into two completely separate cavities or can divide it into a rib-stiffened, contiguous cavity with improved rigidity.

[0076] According to a further preferred embodiment, it is provided that the additive manufacturing method is a wire- or powder-assisted welding deposition method in which material is deposited selectively on the basis of the geometry of the basic body structure by melting a metal wire or powder, in particular by continuously melting along a welding path, the course of which is controlled on the basis of geometric data of the basic body structure, and / or by melting in an electric arc or a laser beam.

[0077] This design of the additive manufacturing process enables efficient production of the body's basic structure and enables rapid and highly resilient material buildup, even for large body structures measuring more than one meter. The welding deposition process allows for the processing of various alternative metallic materials and can therefore easily meet the strength requirements for displacement bodies or housings of positive displacement pumps.

[0078] It is further preferred if, in the additive manufacturing process, a material application head is moved multi-axially relative to the build surface. The multi-axial movement of the material application head, on the one hand, enables movement of the material application head along the respective layer plane in which a layer of the body's basic structure is produced. Furthermore, the movement in the vertical direction, i.e., perpendicular to this layer plane, can be achieved by the multi-axial movement of the application head. Furthermore, it is preferred if the application head is pivotably mounted and this pivoting movement is also a component of the multi-axial movement of the application head. Such pivotability can improve the angle of incidence at which the arc is ignited from the application head in such a way that additive production of overhangs and overlaps is also achieved.which exceed a value of 25° to the vertical direction, which is typical for the WAAM process, for example. The multi-axis movement of the application head is generally understood, in the sense of the invention, as a relative multi-axis movement between the substrate plate and the application head. In this sense, an axis of movement for the multi-axis movement can also be provided, for example, by rotating the substrate plate.

[0079] The movement of the material application head and the rotation of the build surface around the production rotation axis are preferably controlled using control data derived from geometric data of the basic body structure.

[0080] Preferred embodiments of the invention are explained with reference to the accompanying figures. They show:

[0081] Fig. 1 A perspective, partially transparent representation of a rotary piston pump according to a first embodiment of the invention from obliquely above,

[0082] Fig. 2 A schematic front view of two rotary pistons in a pump housing in a cross-sectional view, according to a second embodiment of the invention,

[0083] Fig. 3a-3c Perspective and partially sectioned views of a third embodiment of a rotary piston according to the invention,

[0084] Fig. 4 A schematic, longitudinally sectioned side view of an eccentric screw pump according to a fourth embodiment of the invention,

[0085] Fig. 5 A schematic perspective view of a stator according to a fifth embodiment of the invention, and

[0086] Fig. 6 A schematic, perspective view of a rotor according to a sixth embodiment of the invention. Referring first to Fig. 1, the basic structure of a rotary lobe pump is as follows: In a pump housing 10, two rotary lobes 20, 21 with a plurality of rotary lobe vanes 20a, b, c, ... 21 a, b, c, ... rotate in an intermeshing manner about two parallel axes of rotation 20', 21 The size of the volume enclosed between two adjacent rotary lobe vanes of a rotary lobe and the inner wall surface of the pump housing, which is significantly influenced by the diameter, length and center distance of the rotary lobes, and the number of rotary lobes and the speed of the rotary lobes determines the delivery volume of this rotary lobe pump according to the principle of a positive displacement pump.Typically, when designing such rotary lobe pumps in a series, the length of the rotary lobes is varied along the rotational axis to increase the displacement under otherwise identical conditions. Accordingly, the pump housing 10 is also designed with a corresponding length in the direction of the rotational axes to match the selected rotary lobe length.

[0087] At a first end, the pump housing 10 is closed by a cover 11, which is shown transparent here and provides a view of the rotary pistons for illustrative purposes. This cover 11 is sealed to a front flange surface 1T of the pump housing by several screws. It can be removed to remove the rotary pistons from the pump housing for maintenance or replacement purposes.

[0088] A lateral inlet opening 12 and an opposite lateral outlet opening 13 are arranged on the housing 10. The flow direction through the inlet and outlet openings 12, 13 is radial with respect to the rotation axes 20', 21' and can also run from the outlet opening to the inlet opening by reversing the direction of rotation of the rotary pistons. The flow direction preferably has no axial component.

[0089] The two rotary pistons 20, 21 are connected on the side opposite the cover 11 to an upper and a lower drive shaft, which extend from a gear housing 30 along the rotation axes 20', 21'. The gear housing 30, like the cover 11, is connected to the pump housing via a flange 1T. In the gear housing, the drive force of an electric motor 40, which drives the upper drive shaft directly or via a gear, is transmitted to the lower drive shaft by means of a gear coupling, and the speed of these two drive shafts is synchronized. As a result, both rotary pistons are driven by the electric motor. In other embodiments, gear synchronization can be dispensed with and, for example, the electric motor can directly drive only one of the two rotary pistons. The other rotary piston is then set in rotation by the meshing power transmission through the driven rotary piston.In other embodiments, each of the two rotary pistons can be directly driven into rotation by a drive motor. In such a case, for example, instead of the cover 11, a drive housing with an electric motor can be provided that directly drives the other rotary piston.

[0090] Fig. 2 shows a second embodiment of the invention. The rotary lobe pump of this embodiment has two four-lobed rotary lobes 120, 121. The rotary lobes are torque-resistantly mounted on drive shafts 131, 132 by means of a tongue and groove connection and are set in rotation by a torque from these drive shafts. This rotation leads to a displacement of fluid due to the meshing of the rotary lobes in the area between the two axes of rotation 120', 121' and to a conveyance of fluid in the outer circumferential area of ​​the rotary lobes. As a result, fluid is conveyed from an inlet opening 112 to an outlet opening 113, whereby conveyance in the opposite direction can also occur by reversing the direction of rotation.

[0091] The rotary pistons slide in the outer circumferential area in a sealing manner on an inner circumferential surface 114, 115 of a pump housing 110. This pump housing is manufactured using a welding process and has a double wall with a cavity 116, 117. The cavity is enclosed by an inner wall 116', 117' and an outer wall 116", 117". The cavity is gas-filled, whereby it is to be understood that a cooling liquid or heating liquid can be guided and circulated in the cavity 116, 117 during operation in order to achieve cooling or heating of the pump and the medium pumped therein - this is also to be understood according to the invention as a gas-filled cavity.

[0092] The inner circumferential surface 114, 115 is created using an additive manufacturing process with a machining allowance, which is subsequently removed by machining in order to achieve a high surface quality and geometric precision of this inner circumferential surface. It then forms two precise partial cylindrical surfaces around the rotation axes 120', 121' and can therefore ensure a secure seal against the piston vane tips sliding along it and minimize wear on these piston vane tips. In the area of ​​the inlet opening 112 and the outlet opening 113, flange surfaces 112', 113' are provided, which serve to form an inlet line or a

[0093] Outlet line to the pump housing in a sealed manner. In the area of ​​these flange surfaces 112', 113', a

[0094] A machining allowance is produced, which is subsequently removed by machining in order to create a flat connection surface and to enable a tight connection of a pipe to the inlet or outlet opening.

[0095] The left rotary piston is depicted in Fig. 2 as a rubber-coated rotary piston, while the right rotary piston is depicted as a fully metal rotary piston. It should be understood that a rotary piston pump always uses two rotary pistons of the same design, i.e., one rubber-coated piston on each side or one fully metal rotary piston on each side. The mixed representation in Fig. 2 merely serves to better explain the possible variants of the invention.

[0096] The left rotary piston 121 has a basic body structure or piston base structure manufactured using a welding process as an additive manufacturing process. It comprises a metallic piston base structure 122, which essentially forms the shape of the rotary piston with the four piston vanes formed thereon, as well as the hub with the inner circumferential surface for connecting to the drive shaft 132. The inner circumferential surface of the central bore of this piston base structure, which serves to connect and center the rotary piston on the drive shaft 132, is manufactured using the additive manufacturing process with a machining allowance, which is expanded beforehand or subsequently in a machining turning process to a target dimension defined with a manufacturing tolerance in order to achieve a centered and virtually play-free connection of the rotary piston to the drive shaft.

[0097] The piston base structure 122 has a cavity 123a, b, c, d in each of the four piston vanes, which is gas-filled and sealed on all sides by the piston base structure. These gas-filled cavities serve to save material and reduce the weight of the rotary piston.

[0098] The gas-filled cavities 123a, b, c, d have an hourglass shape with a larger circumferential width at the piston vane base and at the piston vane head, and a constriction with a smaller circumferential width in the region of the piston vane neck between the piston vane head and the piston vane base. The outer geometry of each piston vane has a corresponding geometry with a slight constriction in the region of the piston vane neck. In other embodiments, the piston vanes can also be designed without such a constriction and can run linearly in the region of the piston vane neck or taper towards the piston vane tip.

[0099] The metallic piston base structure is coated externally with an elastomer layer 124. This elastomer layer is produced by vulcanizing a rubber-elastic material onto the outer wall surface of the piston base structure, which is produced using the additive manufacturing process, and could, for example, also be cold-cast. The elastomer layer 124 is designed with a substantially consistent wall thickness along the entire rotary piston. This is achieved by the fact that the outer wall surface of the metallic piston base structure already predefines the desired geometry of the rotary piston minus an undersize allowance. In some embodiments, a greater wall thickness of the elastomer layer can be provided at particularly stressed areas, for example, in the head region of the piston vanes.This undersize reduction is produced during the additive manufacturing process and corresponds to the desired wall thickness of the elastomer layer, which consequently fills this undersize reduction up to the desired target external dimension of the rotary piston.

[0100] The left rotary piston 121, like the right rotary piston 120, is provided with rotary piston vanes that run in a thread-like manner around the rotational axis 121', 120', so that the rotary piston vanes of the two rotary pistons mesh with each other like a worm gear in the area between the two rotational axes, thereby achieving a pulsation-reduced or even pulsation-free delivery of the medium. The pitch of the thread-shaped course of the rotary pistons is coordinated with the axial length of the rotary pistons in such a way that, in every rotational position of the rotary piston, a delivery chamber remains that is sealed off from the inner circumferential surface of the pump housing by two vane tips. This means that the pitch angle, as the angle between a cross-sectional area and the course of a piston vane, must be steeper the longer the rotary piston is.By maintaining a closed space between two rotary lobe vanes, the conveying effect is achieved and the rotary lobe pump is sealed against backflow in every rotational position.

[0101] The right rotary piston 120 is depicted as a metallic rotary piston. It has a metallic piston base structure formed by an outer, multiply curved wall surface, produced using an additive manufacturing process, on the one hand, and an inner, cylindrical wall surface, on the other hand, which connect to each other in the region of the recesses between two piston wing tips. This piston base structure 125 of the right rotary piston 120 thus directly represents the outer surface of the rotary piston, which meshes with the other rotary piston (which, in the actual application, is also fully metallic, in contrast to Fig. 2) and is in sealing sliding contact with the pump housing, as well as the inner cylindrical circumferential surface of the rotary piston, which is attached to the drive shaft.Both the outer surface of the rotary piston and the inner cylinder circumferential surface of the rotary piston are produced using the additive manufacturing process with a machining allowance, which is removed in a subsequent machining process in order to create a high surface quality and geometric precision of these surfaces.

[0102] The wall thickness of the piston base structure is essentially uniform, so that the outer surface of the rotary piston is formed by a multiply curved wall. This wall is bounded inwardly by a correspondingly congruently extending inner curved wall surface. This inner curved wall surface encloses a gas-filled cavity 126a, b, c, d in each piston lobe of the rotary piston 120. This gas-filled cavity is bounded radially inwardly by the wall structure of the piston base structure, which surrounds the inner cylindrical circumferential surface of the rotary piston. The gas-filled cavities 126a, b, c, ... in turn serve to save material and reduce the weight of the rotary piston.

[0103] Referring now to Figs. 3a-3c, a third embodiment of the invention is depicted in the form of a four-lobed rotary piston with a rubber-elastic coating. Fig. 3b shows the basic piston structure, which is formed from a hub structure 210 and four radially extending piston lobe structures 220a, b, c, d attached thereto. The hub structure and the piston lobe structures can be manufactured using an additive manufacturing process, for example, in such a way that the piston lobe structure is built up in a layer-by-layer manufacturing process with the individual layers stacked on top of one another along the direction of the rotation axis 200' of the rotary piston. Alternatively, the hub structure 210 of the rotary piston can be prefabricated as a tube section, and the outer peripheral surface of this tube section can serve as the mounting surface for the four lobe structures of the rotary piston.In this case, the four vane structures are each built up layer by layer in a radial direction on the outer circumferential surface of this hub structure 210 using an additive manufacturing process. Each piston vane structure 220a, b, c, d has a house-shaped cross-section with two wall surfaces extending almost parallel in the vane root area and a gable-shaped extension of the two wall surfaces toward a piston vane tip in the vane tip area of ​​the piston vane. The piston vane structure encloses a gas-filled cavity 226 in each of the rotary piston vanes.

[0104] The piston vane structures 220a-d and the hub structure 210 form a piston base structure, which, as can be seen in Figs. 3a, 3c, is coated with a rubber-elastic layer 224. This rubber-elastic layer 224 is applied directly to the piston vane structures 220a-d produced using the additive manufacturing process and thus adheres particularly well to the rough surface of these piston vane structures due to the manufacturing process, so that only treatment with a primer is necessary before applying the rubber layer. Separate preparation or processing of this surface of the piston vane base structures to improve adhesion can therefore often be limited to cleaning and degreasing or can be omitted entirely, without adversely affecting the adhesion of the rubber-elastic layer.

[0105] The piston wing structures are constructed in the additive manufacturing process with an undersize reduction on their outer surface in order to create, as previously explained, the necessary space for the coating with a rubber-elastic layer up to the desired size.

[0106] Fig. 4 shows a third embodiment of the invention, which is designed as an eccentric screw pump. The eccentric screw pump has a stator 310 and a rotor 320 rotating therein about a rotor longitudinal axis 320'. The outer circumferential surface of the rotor 320 is provided with a multi-start, steep thread structure with rounded thread pitches and rolls in a matching multi-start internal thread structure of the stator, which has one more pitch than the external thread structure of the rotor. The rotor therefore performs a rotating movement about a stator central longitudinal axis 310', i.e., the rotor rotates about its rotational axis, and the rotational axis 320' of the rotor rotates about the stator longitudinal axis.

[0107] The rotor 320 is connected at an inlet end of the stator to a wobble shaft 330, which in turn is connected to a drive motor 350 via a gear 340. The wobble shaft drives the rotor for its eccentric rotational movement by means of two universal joints 331, 332. The rotor 320 is formed by a curved wall produced using an additive manufacturing process. The wall encloses an internal gas-filled cavity 326, through which a fastening screw extends from the outlet end of the rotor to a flange connection surface with which the rotor is attached to the left universal joint 331 of the wobble shaft.In the area of ​​this flange connection surface for connecting to the universal joint, the rotor is manufactured with a machining allowance using the additive manufacturing process. This allowance is removed to a specified dimension in a subsequent machining process to create the necessary surface quality and geometric precision for a conical connection to the universal joint. The fastening screw 322 serves to apply a corresponding tensile force to this conical connection and can be loosened by screwing it in at the outlet end of the rotor.

[0108] The stator 310 is also formed by a curved housing wall, and this wall also encloses a gas-filled cavity 316. During operation of the pump, the fluid to be pumped and the rotor are arranged in the gas-filled cavity 316. The curved housing wall 311 of the stator has an internal geometry that corresponds to the multi-start stator thread structure. This internal surface can be manufactured with a machining allowance using the additive manufacturing process in order to subsequently produce a geometrically precise surface using a machining process and thus produce a purely metallic stator. However, it is preferred to produce the internal surface of the stator base structure using the additive manufacturing process with an undersize reduction, which is filled to a desired internal dimension by an internal lining with a rubber-elastic material in a subsequent coating process.This elastomer coating in the interior of the stator can be designed with a substantially uniform wall thickness, since the metallic stator base structure in the additive manufacturing process already geometrically provides the thread geometry of the multi-start internal thread of the stator.

[0109] The wall thickness of the stator base structure is essentially uniform, so that the multi-start thread structure is also reflected on the outer circumferential surface of the stator. Consequently, the stator is not provided with a cylindrical circumferential surface on the outside, but rather with a multi-start external thread surface. This design results in material savings and maintains the rigidity of the stator. On the inlet and outlet sides, the stator is provided with end-face flange surfaces 311, 312, which are produced, for example, using additive manufacturing with a machining allowance in order to achieve a surface quality and geometric precision sufficient for a sealed connection to the inlet housing or outlet housing through mechanical post-processing.Alternatively, flange surfaces can also be formed by the substrate plate on which the stator is mounted, or they can be subsequently connected to the stator as a prefabricated plate. The flow through the stator is axial.

[0110] The wobble shaft 330 rotates in an inlet housing having an inlet opening 333. At the outlet end of the stator 310, an outlet housing 360 is sealingly attached, which has an outlet opening 363.

[0111] Fig. 5 schematically shows a stator base structure produced using the additive manufacturing process. Starting from a build-up surface 410, the stator base structure extends as a curved wall surface, which, with its inner and outer surfaces, forms a multi-start thread-like course with rounded thread turns in the vertical direction along the stator central longitudinal axis 410'. The stator base structure is built up in the vertical direction along the central longitudinal axis 410', resulting in a layered structure schematically represented by layer boundaries 411 a, b, c,... in Fig. 5. These layer boundaries lie approximately perpendicular to the central longitudinal axis 410' in cross-sectional areas. At the front end, the stator base structure is provided with a flange 411, 421 each for connection to the outlet or inlet housing of the eccentric screw pump.The inner cavity has, as can be seen at the upper end, an oval cross-section, which is due to the two-start design of the stator's thread. The stator shown in Fig. 5 changes its cross-sectional profile from a circular cross-section on the inlet side to an oval and back again to a circular cross-section on the outlet side. The circular cross-sections on the inlet and outlet sides make it easier to connect the stator to existing inlet and outlet flanges. With this design, there is no need to insert a cover layer or flange plate. It should be understood that three-, four-, or more-start thread designs can also be implemented on the stator; in this case, an opening in the shape of a rounded triangle, a rounded square or cloverleaf results at the end of the stator, or an opening shaped like a rounded polygon.Fig. 6 shows a schematic illustration of a basic rotor structure for an eccentric screw pump. The basic rotor structure is designed as a curved wall structure having a thread-like course of a single-start thread on its outer surface and its inner surface. The rotor thus corresponds to a tube with a circular cross-section that has a spiral course of its central longitudinal axis. The basic rotor structure can in turn, as already explained with regard to the stator according to Fig. 5, be built up in a vertical direction on a construction surface (not shown here) by stacking layers on top of one another in the direction of a rotor longitudinal axis 520'. It should be understood that this stacking can be carried out by producing the wall structure of the rotor in a build-up welding process by spirally traversing the central longitudinal axis of the rotor with the welding application head.This results in helical layer boundaries, symbolically represented by lines 511 a, b, and c. The rotor is manufactured using an additive manufacturing process on its outer peripheral surface and its two end-face annular surfaces 511, 521 with a machining allowance, which is removed to a desired dimension in a subsequent machining operation in order to achieve a high surface quality and precision. The rotor has a substantially constant wall thickness and encloses a gas-filled cavity 526 in its interior, which remains gas-filled during operation, thus resulting in significant weight and material savings.The gas-filled cavity can be used to accommodate a mounting screw for attaching the rotor to the wobble shaft or to insert a long tool for tightening and loosening a screw at the inlet end of the rotor that attaches the rotor to the wobble shaft or a joint of the wobble shaft.

[0112]

[0113] 10, Pump housing cover

[0114] 11' flange

[0115] 12 Inlet opening

[0116] 13 Outlet opening

[0117] 20, 21 rotary pistons

[0118] 20a, b,c.., 21a, b,c... rotary piston vanes

[0119] 20', 21' rotation axes

[0120] 30 Gearbox housing

[0121] 40 electric motor

[0122] 110 Pump housing

[0123] 112 Inlet opening

[0124] 113 Outlet opening

[0125] 112', 113' flange surfaces

[0126] 114, 115 inner circumferential surface

[0127] 116, 117 cavity

[0128] 116', 117' inner wall

[0129] 116", 117" outer wall

[0130] 120 right rotary piston

[0131] 121 left rotary piston

[0132] 120, 121 lobed rotary pistons

[0133] 120', 12 1' rotation axes

[0134] 122 piston basic structure

[0135] 123a,b,c cavity

[0136] 124 Elastomer layer

[0137] 125 piston basic structure

[0138] 125, 126 drive shafts

[0139] 126a,b,c... gas-filled cavity

[0140] 132 drive shaft

[0141] 200' rotation axis

[0142] 210 Hub structure

[0143] 210, 220a-d piston vane basic structure

[0144] 220 rotor

[0145] 220' rotation axis

[0146] 220a,b,c,d piston wing structure - M -

[0147] 224 rubber-elastic layer

[0148] 226 gas-filled cavity

[0149] 310 Stator

[0150] 311 curved housing wall

[0151] 320 rotor

[0152] 321 gas-filled cavity

[0153] 320' rotor longitudinal axis

[0154] 322 fastening screw

[0155] 330 wobble wave

[0156] 331 , 332 Cardan joints

[0157] 334 Inlet opening

[0158] 340 gearbox

[0159] 350 drive motor

[0160] 360 outlet housing

[0161] 363 Outlet opening

[0162] 400' stator center longitudinal axis

[0163] 410 construction area

[0164] 411a,b,c,... layer boundaries

[0165] 412 flange

[0166] 520' rotor longitudinal axis

[0167] 511a, b, c,... lines

[0168] 526 cavity

Claims

Claims: 1 . Rotary piston for a rotary piston pump, comprising: A piston base structure, comprising o a hub structure with a bearing circumferential surface which extends around a rotation axis of the rotary piston, and o at least two piston wing structures connected to the hub structure, wherein the piston base structure is formed from a first, preferably metallic material, and is preferably covered radially on the outside with a second material which is different from the first material, in particular an elastomer material, characterized in that in one, preferably each piston wing structure in each case at least one, preferably gas-filled, cavity is formed which is enclosed by a piston wing wall of the piston base structure and optionally by an outer circumferential surface of the hub structure and which is free of elastomer material.

2. Rotary piston according to claim 1, characterized in that the piston vane structure is partially or completely manufactured in an additive manufacturing process, preferably on an outer peripheral surface of the hub structure in a radial construction direction with respect to the axis of rotation.

3. Rotary piston according to claim 1 or 2, characterized by one or more ribs extending through the cavity, wherein preferably one or more ribs extend through each cavity.

4. Rotary piston according to one of the preceding claims, characterized in that each of the at least two piston wing structures has a piston wing wall, which preferably encloses the cavity in the piston wing structure, and has a plurality of structural ribs arranged on the piston wing wall outside the cavity, which are preferably manufactured in one or the additive manufacturing process.

5. Rotary piston according to claim 4, characterized in that the structural ribs Comprises one or more circumferential ribs which extend substantially along a circumferential direction with respect to the axis of rotation over the piston vane wall and which preferably run parallel to one another and / or comprises one or more axial ribs which extend substantially along an axial direction with respect to the axis of rotation, and / or comprises one or more radial ribs which extend substantially along a radial direction with respect to the axis of rotation, and / or one or more axial-radial ribs which extend substantially along the circumferential longitudinal direction of a vane, in particular extend helically along a vane running with a pitch around the axis of rotation.

6. Rotary piston for a rotary piston pump, comprising: a piston base structure, comprising o a hub structure with a bearing circumferential surface which extends around a rotation axis of the rotary piston, and o at least two piston vane structures connected to the hub structure, wherein the piston base structure is formed from a first, preferably metallic material and is preferably radially outwardly enveloped with a second material which is different from the first material, in particular an elastomer material, characterized in that the piston base structure is partially or completely produced in an additive manufacturing process, in particular a wire- or powder-assisted welding process, and wherein the second material fills an undersize reduction in the piston base structure and has an external geometry which corresponds to a desired geometry of the rotary piston.

7. Rotary piston according to one of the preceding claims 1 or 3-6, characterized in that the piston base structure is constructed in an additive manufacturing process in a radial or in an axial construction direction with respect to the axis of rotation.

8. Rotary piston according to claim 6 or 7, characterized in that in one, preferably each piston wing structure at least one, preferably gas-filled, cavity is formed, which is enclosed by a piston wing wall of the piston base structure and optionally by an outer peripheral surface of the hub structure and which is free of elastomer material, wherein preferably the piston base structure has an outer wall with an outer wall surface and an inner wall surface, and the cavity lies radially inward of the inner wall surface with respect to the axis of rotation, and further preferably the axis of rotation lies in the cavity.

9. A pump housing for a rotary piston pump, comprising a body base structure comprising an outer wall produced in an additive selective application process, in which a material forming the outer wall is dispensed layer by layer along one or more paths via a multi-axis moving application head, thereby building up the outer wall, wherein the outer wall is a curved wall with an outer wall surface and an inner wall surface, which has a surface mechanically produced in a machining process in the form of two intersecting partial cylindrical surfaces, which is produced by applying a machining allowance as a post-processing difference in the additive selective application process, so that the geometric dimensions exceed a target geometry of the inner wall surface,and by removing material to a thickness that compensates for the post-processing difference in a subsequent machining process, the surface of the inner wall surface is produced, wherein the basic body structure further comprises a flange surface having a flange surface mechanically produced in a machining process, which is produced by applying a machining allowance as a post-processing difference in the additive selective application process, so that the geometric dimensions exceed a desired geometry of the flange surface, and by removing material to a thickness that compensates for the post-processing difference in a subsequent machining process, the flange surface is produced, wherein preferably the application head is moved along path sections that run transversely to the inner wall surface of the wall, in particular at an angle of 50° - 90° to the inner wall surface.

10. Rotary lobe pump comprising a rotary lobe according to any one of the preceding claims 1-8 or a rotary lobe manufactured by a method according to any one of claims 20-33 and / or a pump housing according to claim 9.

11. Rotor for an eccentric screw pump, comprising: a rotor base structure, comprising o a hub structure with a bearing peripheral surface extending around a longitudinal axis of rotation of the rotor, and o a threaded structure connected to the hub structure, extending along the longitudinal axis of rotation and having a ■ outer wall surface having a thread structure wound around the longitudinal axis of rotation, and ■ has an inner wall surface which encloses a cavity, characterized in that the rotor base structure is produced partially or completely in an additive manufacturing process, in particular a wire- or powder-assisted welding process, and the thread structure is formed by a curved wall with a substantially constant wall thickness, whereby the inner wall surface extends substantially congruently radially inward with respect to the longitudinal axis of rotation from the outer wall surface and the axis of rotation extends in the cavity.

12. Rotor according to claim 1 1, characterized in that the rotor base structure is made of a metallic material and has a surface which is formed by producing the outer wall surface with a machining allowance in the additive manufacturing process, which is subsequently removed by a machining process down to an outer geometry which corresponds to a desired geometry of the rotor.

13. Stator for an eccentric screw pump, comprising: a stator base structure which extends along a stator longitudinal axis and o has an inner wall surface which has a thread geometry winding around the stator longitudinal axis and encloses a cavity in which the stator longitudinal axis runs, and o has an outer wall surface, characterized in that the stator base structure is formed by a curved wall with a substantially constant wall thickness, whereby the Outer wall surface extends substantially congruently radially outwardly with respect to the stator longitudinal axis from the inner wall surface.

14. The stator of claim 13, wherein the stator base structure is formed of a metallic material.

15. Stator according to claim 13 or 14, characterized in that the stator basic structure is partially or completely manufactured in an additive manufacturing process, in particular a wire- or powder-supported welding process 16. Stator according to claim 15, characterized in that the wall of the stator basic structure comprises a metallic wall layer and a layer of an elastomer material, wherein the metallic wall layer has an inner undersize cut-off which is filled in a subsequent application process with the elastomer material which forms the desired geometry of the inner wall surface.

17. Stator according to one of the preceding claims 13-16 or rotor according to one of the preceding claims 11-12, characterized in that the stator or rotor extends from an end-side initial cross-section to an opposite end-side end cross-section and between the initial cross-section and the end cross-section a central section is arranged with a central cross-section which has an outline deviating from a circular cross-section, in particular an oval, triangular cloverleaf-shaped or quadrangular cloverleaf-shaped outline, and wherein furthermore The initial cross-section has a circular outline, and / or The final cross-section has a circular outline.

18. Eccentric screw pump with a rotor according to one of claims 11-12 and / or a stator according to one of claims 13-15, wherein the rotational longitudinal axis of the rotor is arranged parallel and eccentrically to the stator longitudinal axis. Use of an additive manufacturing device, in particular a wire- or powder-supported welding application device, for Manufacturing of a piston base structure of a rotary piston of a rotary piston pump on a prefabricated hub with a build direction in the additive Manufacturing device extending radially outward with respect to a rotational axis of the hub, or Production of a piston base structure of a rotary piston of a rotary piston pump on a substrate plate with a build-up direction in the additive manufacturing device which runs axially with respect to a rotation axis of the rotary piston or Production of a stator base structure of a stator of an eccentric screw pump with a construction direction in the additive manufacturing device, which runs axially with respect to a rotation axis of the rotary piston, in particular in such a way that in the additive manufacturing device a wall is produced which encloses a, preferably gas-filled, cavity, and / or in the additive manufacturing device a wall is produced which has a machining allowance compared to a target geometry and the Machining surcharge after additive manufacturing in a machining Machining device is removed so that the surface of the piston base structure is reduced to a target size, and / or in the additive manufacturing device a wall is produced which has an undersize reduction compared to a target geometry and the undersize reduction is filled with an elastomer material up to the target geometry after the additive manufacturing in a coating device so that the piston base structure is covered with an elastomer material or the stator base structure is lined with an elastomer material.

19. Use of an additive manufacturing device, in particular a wire- or powder-assisted welding application device, for Production of a pump housing base structure of a rotary piston pump, wherein the pump housing base structure has a wall with intersecting partially cylindrical wall inner surfaces arranged around two axes of rotation within a pump chamber, on a substrate plate with a build-up direction in the additive manufacturing device which runs axially with respect to the two axes of rotation, or Production of a rotor base structure of a rotor of an eccentric screw pump, wherein the rotor base structure has a wall with an outer wall surface winding in a thread geometry around a rotation axis, on a substrate plate with a construction direction in the additive manufacturing device which runs axially with respect to the rotation axis of the rotor, in particular in such a way that the inner wall surface of the wall produced in the additive manufacturing device encloses a, preferably gas-filled, cavity and the wall thickness of the wall is substantially constant along the entire length of the wall, so that the outer wall surface runs substantially parallel to the inner wall surface, and / or a machining allowance is produced on the inner wall surface or the outer wall surface in the additive manufacturing device, and after the additive manufacturing, the pump housing base structure produced therein or the rotor base structure produced therein is post-machined in a machining device in order to remove the machining allowance and thereby form a desired inner geometry of a pump housing and a desired geometry of a pump housing flange from the pump housing base structure, or to form a thread-shaped desired outer geometry of a rotor from the rotor base structure.

20. A method for producing a displacement body or a housing of a displacement pump, such as a rotary lobe or pump housing for a rotary lobe pump or a rotor or stator for an eccentric screw pump, comprising the steps: Providing a construction area Building a basic body structure on the building surface in an additive manufacturing process, in particular a wire- or powder-assisted welding deposition process, characterized in that the building of the basic body structure comprises the step of: building a wall of a displacer or housing structure delimiting an inner, preferably gas-filled, cavity on the building surface and enclosing the gas-filled cavity with the delimiting wall.

21. Method according to claim 20, characterized in that the displacement body or the housing is manufactured in the additive manufacturing process by building up layers in a layer-by-layer manufacturing process and the layers are stacked on top of one another along a direction which corresponds to an axis of rotation about which the displacement body or about which a displacement body arranged in the housing rotates during operation.

22. Method according to claim 20 or 21, characterized in that the body base structure is manufactured in the additive manufacturing process, in particular a wire- or powder-assisted welding deposition process, wherein the body base structure has a prefabrication surface which, with a post-processing difference, which is a machining allowance or an undersize reduction, corresponds to a desired geometry of the displacement body of the displacement pump, and the prefabrication surface is post-processed by adding or removing material to a thickness that compensates for the post-processing difference, preferably further comprising a first post-processing step in which the machining allowance on the peripheral surface is removed to a desired dimension in a machining process, and / or preferably further comprising a second post-processing step in which the prefabrication outer surface of the displacement structure is coated with a layer of an elastomer material,which fills the undersize allowance and has an outer geometry that corresponds to a target outer geometry of the rotary piston or a target inner geometry of the stator.

23. A method according to claim 22 for producing a rotary piston or stator, characterized in that the body base structure o has a hub or flange structure with a circumferential surface that runs rotationally symmetrically around a rotational axis of the displacement body and that has a machining allowance, o has a displacement structure, wherein the displacement structure has at least two displacement structures formed radially inward or outward from the hub structure, which extend in the radial direction with respect to the rotational axis and are spaced from one another in the circumferential direction and which have an undersize reduction on their prefabrication outer surface as a post-processing difference, wherein the post-processing comprises a first step in which the machining allowance on the circumferential surface is removed to a desired dimension in a machining process, and the post-processing comprises a second step,in which the prefabricated outer surface of the displacement structure is coated with a layer of an elastomer material that fills the undersize and creates a, Has an external geometry that corresponds to a desired external geometry of the rotary piston or a desired internal geometry of the stator.

24. Method according to one of the preceding claims 20-23 for producing a rotary piston, characterized in that the construction of the body base structure comprises the step of: constructing a body base structure with at least two piston wing structures and enclosing a gas-filled cavity in each piston wing structure with the curved wall, wherein during any subsequent coating the preferably gas-filled cavity remains free of elastomer material.

25. Method according to one of the preceding claims 20-24, characterized in that when building up the basic body structure at least two piston wing structures are built which are arranged angularly offset from one another in the circumferential direction around the axis of rotation and wherein each piston wing structure has an enveloping contour which, starting from a piston wing root which is arranged adjacent to the circumferential surface and has a root width in the circumferential direction around the axis of rotation, extends in the radial direction to a piston wing head which has a head width in the circumferential direction around the axis of rotation, wherein the enveloping contour between the piston wing root and the piston wing head has a piston wing neck which has a neck width in the circumferential direction around the axis of rotation, wherein the neck width is less than or equal to the foot width and preferably the head width is less than or greater than the neck width.

26. Method according to claim 25, characterized in that, during the construction of the body base structure, a preferably gas-filled cavity is enclosed in each piston wing structure, which cavity extends from the piston wing root, which is arranged adjacent to the circumferential surface and has a root cavity width in the circumferential direction around the rotation axis, in the radial direction to the piston wing head, which has a head cavity width in the circumferential direction around the rotation axis, and the cavity between the piston wing root and the piston wing head has a neck cavity width in the circumferential direction around the rotation axis, wherein the neck cavity width is less than or equal to the foot cavity width and preferably the head cavity width is less than or greater than the neck cavity width.

27. Method according to one of the preceding claims 20-26, characterized in that the basic body structure comprises at least one displacer structure, in particular two piston wing structures, and in that each displacer structure has a wall which preferably encloses a cavity, in particular a gas-filled cavity, and which has a plurality of external build-up ribs which are built up on the wall in the additive manufacturing process, wherein the build-up ribs are preferably located in a post-processing difference designed as an undersize reduction.

28. Method according to claim 27, characterized in that the structural ribs comprise a group of circumferential ribs which extend substantially along the circumferential direction over the wall and which preferably run parallel to one another and that the structural ribs preferably comprise one or more axial ribs which extend substantially along the axial direction with respect to the axis of rotation.

29. A method for producing a displacement body or a housing of a displacement pump, such as a rotary lobe or pump housing for a rotary lobe pump or a rotor or stator for an eccentric screw pump, comprising the steps: Providing a construction area, Building a body base structure on the construction surface, wherein the body base structure has a prefabrication outer surface which corresponds to an outer geometry of the displacer body with a post-processing difference which is a machining allowance or an undersize reduction, post-processing the prefabrication outer surface by adding or removing material in a thickness which compensates for the post-processing difference, characterized in that the body base structure is produced in an additive manufacturing process, in particular a wire- or powder-supported welding process, and the body base structure has a hub structure with a flange surface which is rotationally symmetrical about a rotation axis of the displacer body and which has a machining allowance, wherein the post-processing comprises a first step comprises, in which the machining allowance on the flange surface is removed down to a target dimension in a machining process, and has a displacer structure which winds around the axis of rotation and which has a radial machining allowance on its prefabrication outer surface as a post-machining difference, wherein the post-machining comprises a second step in which the machining allowance on the prefabrication outer surface is removed down to a target dimension in a machining process, or has a displacer structure which winds around the axis of rotation and which has a radial undersize reduction on its prefabrication outer surface as a post-machining difference, wherein the post-machining comprises a second step in which the undersize reduction on the prefabrication outer surface is filled up to a target dimension in a coating process.

30. Method according to claim 29, characterized in that the displacer structure is preferably thread-shaped and has a thread depth in the radial direction with respect to the axis of rotation.

31. Method according to claim 29 or 30, characterized in that the construction of the basic body structure comprises the step of: constructing the displacer structure as a wall defining an inner, preferably gas-filled cavity on the construction surface and enclosing the gas-filled cavity with the defining wall.

32. Method according to one of the preceding claims 29 to 31, characterized in that The construction surface is a surface of a substrate plate, and the body basic structure is built up layer by layer in the direction of the rotation axis of the displacer body or the housing on the surface of the substrate plate and the rotation axis is perpendicular to the surface of the substrate plate.

33. Method according to one of the preceding claims 29 to 32, characterized in that a set of assembly production data for controlling the assembly of the basic body structure is generated from geometric target data of the displacement body or housing in an additive manufacturing process and the assembly of the The basic body structure is controlled using this build-up production data set, and a removal production data set is created from the geometric target data and / or the build-up production data set, and the post-processing is carried out by multi-axis milling which is controlled using the removal production data set.

34. A method for producing a stator of an eccentric screw pump, comprising the steps: Providing a construction area, Building a body base structure on the construction surface, wherein the body base structure has a prefabrication outer surface which corresponds to an outer and inner geometry of the stator with a post-processing difference which is a machining allowance or an undersize reduction, post-processing the prefabrication outer surface by adding or removing material in a thickness which compensates for the post-processing difference, characterized in that the body base structure is produced in an additive manufacturing process, in particular a wire- or powder-assisted welding deposition process, and the body base structure comprises a curved wall with an inner wall surface and an outer wall surface which extends in the axial direction with respect to the axis of rotation, wherein ■ the inner wall surface surrounds the rotation axis and has at least two threads that wind around the rotation axis, ■ the inner wall surface has an undersize reduction as a finishing difference, and ■ the prefabrication outer surface comprises a prepared flange surface which has a machining allowance as a finishing difference, the finishing comprises a first step in which the machining allowance on the prepared flange surface is removed in a machining process down to a desired dimension and a flange surface is thereby produced, and the finishing comprises a second step in which the inner wall surface is coated with a layer of an elastomer material which undersize allowance and has an internal geometry that corresponds to the target geometry of the stator.

35. A method for producing a pump housing of a rotary lobe pump, comprising the steps: Providing a construction surface that is perpendicular to a rotation axis, constructing a body base structure on the construction surface, wherein the body base structure has a prefabrication flange surface and a prefabrication inner wall surface, which corresponds to a flange surface and an inner wall surface of the pump housing with a post-processing difference, post-processing the prefabrication flange surface and the prefabrication inner wall surface by removing material to a thickness that compensates for the post-processing difference, characterized in that the body base structure is manufactured in an additive manufacturing process, in particular a wire- or powder-assisted welding process, and the body base structure comprises a wall that delimits an inner, preferably gas-filled, cavity, with the prefabrication inner wall surface and an outer wall surface that extends in the axial direction with respect to the rotation axis, wherein ■ the prefabrication inner wall surface surrounds the rotation axis and has two intersecting partial cylindrical surfaces, the post-processing comprises a first step in which the machining allowance on the prefabrication flange surface is removed to a target dimension in a machining process and the flange surface is thereby produced, and the post-processing comprises a second step in which the machining allowance on the prefabrication inner wall surface is removed to a target dimension in a machining process and the inner wall surface is thereby produced.

36. Method according to one of the preceding claims 29-35, characterized in that the wall is constructed as a double wall with an inner wall which has the inner wall surface and an outer wall which has the outer wall surface, and at least one preferably gas-filled cavity is formed between the inner wall and the outer wall.

37. Method according to the preceding claims 29-36, characterized in that when building up the basic body structure, one or more ribs are built which extend through the cavity in order to stiffen a wall structure around the cavity, wherein preferably each cavity is stiffened by one or more ribs.

38. Method according to one of the preceding claims 20-37, characterized in that the body base structure, in particular the displacer body, the stator or the pump housing, extends along a production rotation axis, the provision of a construction surface comprises providing a substrate plate with a surface forming the construction surface, the construction of the body base structure comprises building the body base structure on the surface, wherein the surface is oriented horizontally and the body base structure is built up layer by layer in a vertically oriented construction direction thereon, wherein the construction direction runs parallel to the production rotation axis and layers of the layered body base structure lie approximately perpendicular to the production rotation axis, wherein preferably the substrate plate forms an end face of the displacer body, the stator or the pump housing.

39. Method according to one of the preceding claims 20-38, characterized in that the additive manufacturing method is a wire- or powder-assisted welding deposition method in which material is deposited selectively on the basis of the geometry of the basic body structure by melting a metal wire or powder, in particular by continuous melting along a welding path, the course of which is controlled on the basis of geometric data of the basic body structure, and / or the melting takes place in an electric arc or a laser beam.

40. Method according to one of the preceding claims 20-39, characterized in that in the additive manufacturing process a material application head is moved multi-axially relative to the build surface.

41. Method according to one of the preceding claims 20-40, characterized in that the construction surface is rotated about the production rotation axis during the construction of the basic structure.

42. Method according to one of the preceding claims 20-41, characterized in that the basic body structure is constructed as a wall delimiting an inner, preferably gas-filled cavity with an inner wall surface and an outer wall surface, and the wall has a substantially uniform wall thickness.

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