Press body and pump housing for positive displacement pump

Abstract

The invention relates to a rotary piston (20, 21) for a rotary piston pump, comprising: a piston base structure (122), which comprises a hub structure (210) having a bearing circumferential surface, which extends about an axis of rotation of the rotary piston; and at least two piston blade structures (220a-d) connected to the hub structure, the piston base structure being made of a first material, preferably a metal material, and preferably wrapped radially externally with a second material different from the first material, in particular an elastomeric material; the invention is characterized in that at least one cavity (126a-d), preferably a gas-filled cavity, is formed in each piston blade structure, preferably in each piston blade structure, said cavity being surrounded by the piston blade wall of the piston base structure and optionally by the outer circumferential surface of the hub structure, and said cavity being free of an elastomeric material.

Description

Field of the Invention

[0001] The present invention relates to an extrusion body and a housing for a positive displacement pump, such as a rotary piston and a pump housing for a rotary piston pump or a rotor and a stator for an eccentric screw pump. Other aspects of the present invention are methods for manufacturing these components. Background Art

[0002] Rotary piston pumps and eccentric screw pumps belong to the category of positive displacement pumps and are used for conveying various types of media, which in particular also cover contaminated and solid-containing media that carry abrasive particles in themselves. These media can be conveyed by rotary piston pumps and eccentric screw pumps, and these pumps achieve a good service life here. Here, for specific media and in particular for the particles carried in the media, it has been proven to use a rotary piston with an external rubber layer and a stator with an internal rubber lining in order to avoid or at least reduce wear caused by the particles present between the extrusion body and the housing. In other applications, rotary pistons and stators without such a rubber covering are also used.

[0003] Rotary piston pumps and eccentric screw pumps require precise manufacturing of the complex geometric profiles of the extrusion body (rotary piston, rotor) and the housing (rotary piston pump housing, stator) for reliable operation over a long period of time. At the same time, these components should withstand high operating forces and deform / bend as little as possible under these operating forces in order to ensure low-friction and low-wear operation. However, contrary to this desired high precision and stability, the robust structural design that enables this high stiffness results in high weight and high material consumption, which makes the maintenance of the pump difficult and increases the manufacturing cost and furthermore - in the case of eccentric motion, for example in the case of an eccentric screw pump - leads to significant unbalanced forces and associated bearing loads.

[0004] A rotary piston for a rotary piston pump is known from US10982671B1, which has a metallic frame made of multiple metal plates, and the frame is wrapped with a rubber-elastic material. This structural form of the rotary piston allows for a significant reduction in the metallic share of the rotary piston, and at the same time ensures good adhesion of the rubber-elastic share of the rotary piston to the metallic share. Therefore, the weight of the rotary piston can be reduced, and the integrity of the rotary piston will not be adversely changed or delaminated during its service life. However, the drawback of this structural form is the complex prefabrication of the required metal plates and the assembly of these metal plates on the prefabricated hub. In addition, this manufacturing method requires careful selection of processing parameters when wrapping with the rubber-elastic material to avoid the occurrence of undesired concave surface shrinkage between the metal plates due to the shrinkage of the rubber-elastic material during the vulcanization process. Therefore, when implementing planned geometric changes on the rotary piston, this method requires complex conversion or remanufacturing of the manufacturing tools and careful re-determination of the manufacturing parameters for the vulcanization method.

[0005] An eccentric screw pump is known from EP2944819B1, in which the assembly and maintenance of the rotor are simplified in such a way that the stator together with the rotor arranged in the stator can be pivoted unilaterally from the installation position through an inclined flange. The rotor can thus be pulled out of the stator axially in a simplified manner. The purpose of this improvement is that the rotor can be better accessible and can be more easily manipulated, but it does not lead to a reduction in the bare mass of the rotor or the stator in order to simplify the manipulation.

[0006] EP3112682B1 describes an eccentric screw pump with a hollow rotor, and a fixing element for fixing the rotor on a swing shaft passes through or can be accessed through the hollow rotor. Due to this construction of the rotor, the weight of the rotor is reduced compared to a solidly constructed rotor. However, the manufacture of such a rotor is more complex because manufacturing a drill hole over the entire length of such a rotor requires complex additional manufacturing steps for this purpose.

[0007] It is known from EP19749244A1 that the rotor is manufactured by means of a multi-axis controlled milling method or in an SLS / SLM method, or in the case of a smaller eccentric screw rotor, it is made of a plastic material by means of prototyping or 3D printing. Although these alternative manufacturing routes open up the manufacture of rotors with an external geometry that can be implemented with a higher degree of variability compared to the hitherto common turning methods. However, the eccentric screw rotors manufactured in this way are advantageously implemented especially in terms of their surface geometry, but the manufacture in the SLS / SLM method is time-consuming, and these manufacturing methods are especially suitable for small rotors.

[0008] A rotor for use in a Roots compressor is known from DE112017000580T5, which is supposed to be made in a 3D printing method or an additive manufacturing method. The rotor is given a reduced inertia on the one hand in terms of the rotational speed change characteristic ("instantaneous characteristic") and an optimized thermal expansion characteristic on the other hand in order to optimize the device efficiency. The rotor is supposed to have a hollow grid structure, such that a reticulated or approximately reticulated rotor is produced. The drawback here is that in the case of the 3D printing method preferred in this prior art, such cavities cannot be produced in the additive manufacturing method in a gas-filled manner, but rather the uncured raw material (powder, liquid) remains in the cavities and thus needs to be removed afterwards through suitable openings in the walls of the cavities if the cavities are supposed to be filled with gas. This is complex and moreover often not completely successful, especially in the case of split or divided cavities. The cavities in the rotor are supposed to be closed off by the first and second rotor end faces. Each rotor is configured with an axially-radially inclined flow-through direction in order to be used as a synchronously engaged reverse rotor in an expander. The drawback of this structural form is that the axially-radial flow-through of the rotor is not suitable for many application purposes, and the load-bearing capacity of the rotor is insufficient for the conveyance of liquids carrying particles.

[0009] Another rotary blower in the form of a Roots compressor is known from EP1300592A2, wherein a compressible medium (typically air) is compressed by two meshing rotors. The drawback of this structural form is that the accuracy of the geometric structure of the rotors required for conveying an incompressible medium is not sufficient for conveying without leakage of the medium being conveyed.

[0010] An eccentric screw pump is known from DE202016100894U1, wherein the stator sleeve or the rotor is configured as a 3D printed component. The drawback of this manufacturing method is the time-consuming manufacturing process in this manufacturing method. A stator consisting of a plurality of disk-shaped segments is proposed. However, this stator has the following drawbacks: the assembly is complex, and the mutual sealing of the segments needs to be ensured in order to avoid undesired leakage and efficiency losses.

[0011] An eccentric screw pump with a stator lining is known from DE202021106537U1. The stator lining is supported on a stator housing that surrounds the stator lining. This support is supposed to produce a location-dependent support effect in such a way that the stator lining consists of a thin-walled sleeve and a load-bearing structure, which includes a support effect adapted to the local requirements of the sleeve. However, the disadvantages of this structural form are: on the one hand, a high sensitivity to undesired load peaks, for example those caused by foreign objects or pressure peaks, which can irreversibly deform or perforate the thin-walled sleeve structure; on the other hand, the manufacturing duration for such a configured stator and the necessary multiplicity for an efficient manufacturing method are disadvantageous. Summary of the Invention

[0012] Against this background, the object of the present invention is to simplify the maintenance complexity on a positive-displacement pump, such as a rotary piston pump or an eccentric screw pump, even when the positive-displacement pump has a large delivery volume; and in this case, not significantly increase the manufacturing cost for manufacturing the positive-displacement pump.

[0013] The object is solved according to a first aspect of the invention by a rotary piston for a rotary piston pump, which rotary piston comprises:

[0014] - a hub structure having a support circumferential surface that extends around the rotation axis of the rotary piston; and

[0015] - at least two piston blade structures connected to the hub structure, wherein the piston base structure is made of a first material, preferably a metallic material, and is preferably radially externally wrapped with a second material different from the first material, in particular an elastomeric material;

[0016] It is characterized in that at least one cavity, preferably a gas-filled cavity, is respectively formed in the piston blade structure, preferably in each piston blade structure, which cavity is surrounded by the piston blade wall of the piston base structure and optionally by the outer circumferential surface of the hub structure, and the cavity is free of elastomeric material.

[0017] The rotary piston according to the invention is characterized by at least one corresponding cavity, which is arranged in each piston vane structure. The cavity can preferably be filled with gas. The two-vane rotary piston thus has at least two such gas-filled cavities, and the three-vane or more-vane rotary piston accordingly has at least three or correspondingly more such gas-filled cavities. The gas-filled cavities are arranged in the piston vane structure and are thus eccentric with respect to the axis of rotation of the rotary piston and spaced apart. Each cavity is surrounded on the one hand by the outer circumferential surface of the piston base structure, which is typically achieved by the wall of the piston vane structure, and in the event of a possible later covering with elastomer, prevents the introduction of rubber-elastic material. The cavities in each rotary piston can be correspondingly self-enclosed cavities, but can also be configured to be open towards the radial interior, such that the gas-filled cavities in the respective piston vane structures are in fluid communication with each other via the centrally formed hollow inner chamber of the rotary piston. This structural form in particular also allows the rotary piston to be manufactured by a casting method and in so doing to use a core, which can be removed towards the axis of rotation after the casting process in order to thus form the cavities in the piston vane structure.

[0018] The rotary piston additionally has a hub structure, which has a bearing surface. This can be formed in the simplest case by a flange connection surface, by means of which the rotary piston is connected to the drive shaft and is thus supported. The bearing surface can also be formed by a cylindrical inner circumferential surface, by means of which the rotary piston can be fixed to the outer circumferential surface of the shaft and is thus supported.

[0019] A method for manufacturing a rotary piston that is preferred compared to the casting method is an additive manufacturing method, in which the piston basic structure is manufactured during the additive manufacturing process. The additive manufacturing method can be understood in the sense of the present invention as any of the following methods, in which materials are selectively applied and hardened point by point, line by line, or layer by layer, and the product is thus selectively constructed with the aid of geometric data, and in such a way that, for example, the material is selectively applied in a molten state and then solidified, or in such a way that the material is applied as a uniform layer in a powder state or has also been selectively applied, and is solidified and interconnected at selectively selected sites by melting and solidifying. Examples of this are three-dimensional printing methods or surfacing methods. These methods allow cavities to be enclosed by walls directly during the additive manufacturing process, and thus also to configure the gas-filled cavities as self-enclosed cavities. In other methods, such as in laser sintering or laser melting methods, the insufficiently hardened powder material can be removed from such cavities afterwards or retained in the cavities. Such cavities filled with loose powder should also be understood as gas-filled cavities in the sense of the present invention. In principle, a cavity or in particular a gas-filled cavity in the sense of the present invention should be understood as a volume that does not form or is not suitable for receiving or transmitting mechanical forces.

[0020] Thus, according to a first preferred embodiment, it is particularly preferred that the piston vane structure is partially or completely manufactured in an additive manufacturing method, preferably on the outer circumferential surface of the hub structure in the radial building direction with reference to the rotational axis. Typical additive manufacturing methods are, for example, surfacing methods, in which the material is supplied in wire or powder form and selectively melted and thus solidified by an electric arc, laser or otherwise, and connected to the already manufactured partial structure. Other additive manufacturing methods are three-dimensional printing methods, by means of which products are made directly or indirectly, for example in the direct way by printing a curable polymer material or in the indirect way by printing a curable polymer binder material doped with metal powder or ceramic powder and subsequently melting the polymer binder and sintering the metal fraction and the ceramic fraction into the final product. Other additive manufacturing methods contemplated for the present invention are laser sintering methods or laser melting methods, in which the product is manufactured layer by layer in such a way that a powder layer is selectively hardened by means of a laser successively and connected to a powder layer located below this powder layer of the previously hardened structure, and the process is repeated until the product is completed by successive stacking of a plurality of such powder layers.

[0021] An important influencing factor in such an additive manufacturing method is the build direction along which the product is built 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 only allows overhangs to be formed at a defined maximum angle to the build direction, because above this maximum angle a reliable build can no longer be guaranteed reliably. The build includes: a structural connection of an upper layer to a layer below it in an overhang structure. On the other hand, the build direction is also determined and limited by the shape of the structural space of the correspondingly used manufacturing device. According to the invention, on the one hand, it is preferred to build the rotary piston in the axial direction, i.e., with the build direction along the rotational axis of the rotary piston. In this case, the length of the rotary piston can in particular be formed almost without limitation by vertical building in the structural space on a horizontally defined build platform and is only limited in the vertical direction by the height of the structural space. Alternatively, it is preferred to build the piston vane structure in the radial build direction on the outer circumferential surface of the hub structure. In this case, the hub structure is prefabricated, which can be achieved by conventional manufacturing methods or additive manufacturing methods, for example, it can be carried out in a machining process during turning. Then, on the thus produced outer circumferential surface of the hub structure, the piston vane structure is produced by an additive manufacturing method in the radial direction. This can be achieved in such a way that during the additive manufacturing method, the hub structure rotates around the rotational axis of the rotary piston in order to thus provide the degrees of freedom of movement of the additive manufacturing method and thus allow the additive manufacturing process to always be carried out on the upper side of the hub structure with reference to the direction of gravity and thus avoid the undesired flow-away of the additively applied material.

[0022] The structure of the rotary piston according to the invention is characterized in the first-mentioned case in that the layers of the piston vane structure are stacked one after the other in the axial direction, whereas in the second manufacturing method with a radial build direction on the hub structure the layers are stacked one after the other in the radial direction.

[0023] The rotary piston according to the invention can additionally be configured by one or more ribs which extend through the cavity, preferably one or more ribs extend through each cavity. Such ribs can effectively contribute to the reinforcement of the structure and thus generally allow thinner wall thicknesses while maintaining the same stiffness and strength. The ribs can preferably be integrally built in the additive manufacturing method of the rotary piston. The ribs can divide the cavity into two or more separate individual cavity sections which are not in fluid communication with each other; or the ribs can only partially extend into the cavity so that the cavity remains a single cavity.

[0024] Furthermore, it is also preferred that the at least two piston blade structures are arranged at an angle to each other in the circumferential direction around the rotation axis. Each piston blade structure has a piston blade root and a piston blade head arranged radially outside the piston blade root, and a piston blade neck can also be arranged between the piston blade root and the piston blade head. The piston blade root is preferably arranged adjacent to the circumferential surface and has a blade root width arranged centrally in the radial direction, which extends in the circumferential direction around the rotation axis. The piston blade head and the piston blade neck each have a blade head width and a blade neck width centrally in the radial direction in the circumferential direction around the rotation axis, respectively. In this embodiment, there are two piston blade structures, which are arranged at an angle to each other, for example, when there are exactly two piston blade structures, the angle is 180°, and preferably a plurality of piston blade structures are evenly distributed on the circumference of the rotary piston. In principle, the blade head width can be smaller than the blade neck width and the blade root width, and the blade neck width can be smaller than or equal to the blade root width, so that a geometric structure corresponding to a house with a saddle-shaped roof is produced. In other solutions, the blade neck width can also be smaller than the blade root width and the blade head width, so that a waist shape similar to an hourglass cross-section is produced. Therefore, a constriction is produced in the region of the piston blade neck, which also advantageously reproduces the geometric structure of the piston blade for the rotary piston and thus allows the rotary piston to be formed particularly easily, with large cavities in the piston blade and an external geometric structure that is already well approximated to or finally matches the desired geometric structure of the rotary piston, or an external geometric structure that can be covered with an elastomeric layer of constant layer thickness.

[0025] This geometric structure especially allows for effective manufacturing on the circumferential surface of the prefabricated hub structure in the surfacing method, without producing overhangs or build angles that cannot be manufactured or are particularly sensitive in terms of manufacturing parameters. It is also preferred that the cavity width is formed according to the blade head width, the blade neck width, and the blade root width in the piston blade head, the piston blade neck, and the piston blade root, and thus a uniform wall thickness and good utilization of the cavity with maximized cavity volume are achieved.

[0026] In principle, it can be understood in each of the above-described embodiments that in a piston vane composed of a piston vane head and a piston vane root, these two sections respectively occupy half of the total radial height of the piston vane, and the head width or the root width is respectively measured in the middle of the piston vane head or the piston vane root, that is, measured at 1 / 4 or 3 / 4 of the radial height of the piston vane in the radial direction. If the piston vane consists of a piston vane head, a piston vane neck, and a piston vane root, then it can be understood that each of these three sections respectively occupies 1 / 3 of the total height of the piston vane in the radial direction, and the corresponding width of the corresponding section is measured in the middle of this section, that is, measured at 1 / 6, 3 / 6, and 5 / 6 of the radial height of the piston vane.

[0027] Furthermore, it is preferably that each of the at least two piston vane structures has: a piston vane wall, which preferably encloses a cavity in the piston vane structure; and a plurality of construction ribs arranged on the piston vane wall outside the cavity, and the construction ribs are preferably manufactured in one or the same additive manufacturing method. According to this embodiment, each piston vane structure has construction ribs arranged outside, that is, outside the cavity, and these construction ribs can be geometrically formed independently of the possible ribs in the cavity. These construction ribs are used to establish the envelope profile of the rotary piston through the outer contour of these construction ribs, and the envelope profile enables good adhesion of the subsequently applied wrapping material, such as a rubber elastic material.

[0028] Herein, it is particularly preferred that the construction ribs include: one or more circumferential ribs, which extend substantially along the circumferential direction on the piston vane wall with reference to the rotation axis, and the circumferential ribs preferably extend parallel to each other; and / or one or more axial ribs, which extend substantially along the axial direction with reference to the rotation axis. The construction ribs can extend in the circumferential direction or in the axial direction with reference to the rotation axis of the rotary piston according to this solution, or construction ribs can be provided not only in the axial direction but also in the circumferential direction. Through this arrangement structure, effective form-locking support and adhesive attachment of the rubber elastic material covering the piston are achieved on the piston vane structure, and thus, even when there are high loads and forces at the interface between the piston vane structure and the rubber elastic material, layer separation of the rubber covering layer is avoided.

[0029] The object of the present invention is solved according to the second aspect of the present invention by a rotary piston for a rotary piston pump, which rotary piston includes a piston basic structure, and the piston basic structure includes:

[0030] - a hub structure, which has a supporting circumferential surface that extends around the rotation axis of the rotary piston; and

[0031] - At least two piston vane structures connected to the hub structure,

[0032] wherein the piston base structure is made of a first material, preferably a metallic material, and is preferably radially externally wrapped with a second material different from the first material, in particular an elastomeric material;

[0033] characterized in that the piston base structure is partially or completely manufactured in an additive manufacturing method, in particular in a wire-based or powder-based surfacing method; and

[0034] - The at least two piston vane structures extend in the radial direction and are spaced apart from each other in the circumferential direction with reference to the axis of rotation;

[0035] - The second material fills a dimensional undercut of the piston base structure and has an external geometry corresponding to the nominal geometry of the rotary piston.

[0036] According to this embodiment, the rotary piston has a piston base structure which is manufactured in an additive manufacturing method and has a dimensional undercut, i.e. an external geometry which does not correspond to the ultimately desired external nominal geometry of the rotary piston. The piston base structure has at least two piston vane structures, preferably three, four or more piston vane structures, which are evenly distributed on the circumference of the rotary piston. Preferably, it is provided that each piston vane structure has: a first cross-section which lies in a first tangent plane tangential to a first cylindrical surface around the axis of rotation; and a second cross-section which lies in a second tangent plane tangential to a second cylindrical surface around the axis of rotation and which is smaller than the first cross-section, the second cylindrical surface being radially external to the first cylindrical surface.

[0037] The undersize and the cross-sectional enlargement which preferably also constitutes are used to receive a second material and allow the second material to be attached to the piston infrastructure in a particularly advantageous manner. The second material can be an elastomeric material such as a rubber-elastic material. On the one hand, the surface caused by the additive manufacturing method often already has such roughness, and perhaps also has microgrooves due to the layer-by-layer or row-by-row manufacturing method in the additive manufacturing method, so that good adhesion and form-locking force transmission are achieved at the interface with the second material. Especially in the surfacing method, on the one hand, the surface macrostructure is generated by manufacturing in the form of beads, and the surface microstructure is generated due to the formation of scales along the beads. The surface macrostructure and the surface microstructure together are particularly advantageous for the subsequent cladding of the surface, because on the one hand, the effective adhesion surface is increased and on the other hand, form-locking force transmission between the layers and the surface of the rotary piston is achieved. On the other hand, the cross-sectional increase from the radial inside to the outside realizes advantageous undercuts, which also improve the layer connection strength. The second material applied to the piston infrastructure fills the difference from the nominal geometry of the rotary piston caused by the undersize, so that the outer surface of the second material corresponds to the desired nominal geometry of the rotary piston. Therefore, the rotary piston has advantageous mechanical properties, allows the external geometry to be freely constructed geometrically by the additive manufacturing method, and realizes improved adhesion of the second material, i.e., the elastomeric coating, to the material of the piston infrastructure. As in the above-described embodiment of the present invention, it can be understood here that the piston infrastructure is preferably made of a metallic material, which is possible, for example, preferably in the surfacing method.

[0038] In the rotary piston explained above according to the first aspect of the present invention and likewise in the rotary piston according to the second aspect of the present invention, it is preferably provided that the piston infrastructure is constructed in the additive manufacturing method in the radial build direction with reference to the axis of rotation. The radial build direction can be understood here as meaning that the rotary piston is constructed by layers, lines or sections which are stacked successively in the radial direction. Here, the additive manufacturing typically starts on the circumferential surface of a prefabricated hub structure, which serves as a cylindrical build surface. Thus, effective manufacturing with a load-bearing structure is possible.

[0039] In the rotary piston explained above according to the first aspect of the invention and, alternatively, in the rotary piston according to the second aspect of the invention, it is provided that the piston basic structure is constructed in an additive manufacturing method in the axial build direction with reference to the rotary axis. The axial build direction can be understood here as meaning that the rotary piston is constructed by layers, lines or segments which are stacked successively in the axial direction. The build direction of the layers, lines or segments thus corresponds to the direction of the rotary axis of the rotary piston. It is understood that the construction of the rotary piston can be achieved, for example, by applying material in a layer plane in the circumferential direction or in the radial direction or in a direction composed of the circumferential direction and the radial direction, and after the material construction in this layer plane has ended, the construction is continued in a layer plane spaced apart axially above this layer plane, thus determining the build direction. This axial build direction also results in a corresponding stacking structure in the piston basic structure, which stacking structure is formed by the correspondingly visible interfaces between the individual layers, lines or segments, which interfaces delimit the axial stratification of the rotary piston from one another. These interfaces each have sufficient strength on the basis of the principle of the additive manufacturing method, such that they are not lower or not significantly lower than the strength of the base material, for example because one layer fuses with the layer below it. However, the interfaces are visible microscopically, for example, in the corresponding material structure in a micrograph or also on the outer surface of the rotary piston.

[0040] Furthermore, it is also preferred that in the piston vane structure, preferably in each piston vane structure, at least one cavity, preferably a gas-filled cavity, is formed accordingly, which cavity is surrounded by the piston vane wall of the piston basic structure and possibly by the outer circumferential surface of the hub structure, and which cavity is free of elastomeric material. Preferably, the piston basic structure has an outer wall with an outer wall surface and an inner wall surface, and the cavity is located radially inside the inner wall surface with reference to the rotary axis. Furthermore, it is preferably that the rotary axis is located in the cavity. According to this embodiment, in the additive manufacturing method, a cavity is formed in each piston vane of the rotary piston. The cavity can be closed or can be open towards the rotary axis of the rotary piston, such that the gas-filled cavities of the respective rotary piston vanes are formed by cavity segments of possibly only one single cavity, in such a way that the cavity extends into each piston vane in the manner of a blind hole. In principle, it is understood that a rotary piston in which a cavity is further formed in the piston vanes in such a way can be further constructed in the same way as has been explained above for the rotary piston according to the first aspect of the invention.

[0041] The object of the invention in accordance with the third aspect of the invention is solved by a pump housing for a rotary piston pump, which pump housing comprises: a main body infrastructure, which main body infrastructure comprises an outer wall, which outer wall is produced in an additive selective application method, in which method the material forming the outer wall is discharged layer by layer along one or more trajectories by means of an application head with multi-axis movement and thus the outer wall is constructed, the outer wall being a curved wall having an outer wall surface and an inner wall surface, the curved wall having a surface produced mechanically in a machining manufacturing method in the form of two intersecting partial cylindrical surfaces, which surface is produced in such a way that in the additive selective application method an additional machining amount is applied as a reworking difference such that the geometric dimensions exceed the nominal geometric structure of the inner wall surface, and the inner wall surface is produced by removing material in a subsequent machining method by a thickness compensating for the reworking difference, wherein the main body infrastructure further comprises a flange surface having a flange surface produced mechanically in a machining manufacturing method, which flange surface is produced in such a way that in the additive selective application method an additional machining amount is applied as a reworking difference such that the geometric dimensions exceed the nominal geometric structure of the flange surface, and the flange surface is produced by removing material in a subsequent machining method by a thickness compensating for the reworking difference, preferably the application head moves along a plurality of trajectory segments which extend transversely to the inner wall surface of the wall, in particular at an angle of 50° to 90° to the inner wall surface. According to this embodiment, the pump housing for a rotary piston pump is produced in an additive manufacturing method. Here, the pump housing is produced with its internal geometry defined by the inner wall surface such that in the additive manufacturing method an additional machining amount is constructed which is removed again in a subsequent machining method in order thus to produce the exact geometric structure of the inner wall surface, which geometric structure has a high surface quality and is thus suitable for the sealing interaction with the rotary piston running in this inner wall surface. It will be understood that this housing according to the third aspect of the invention preferably interacts with the rotary piston according to the first or second aspect of the invention. According to the invention, the main body infrastructure further has a flange surface which also has an additional machining amount which is removed in a machining method following an additive manufacturing method in order thus to produce the flange surface which serves for connection to a transmission housing, a drive housing or serves for connection of a lid or serves for connection of an inlet pipe or an outlet pipe. Correspondingly, the pump housing can also have a plurality of such flange surfaces, for example four flange surfaces, which provide for the respective connections mentioned above.It can be understood here that the flange for connecting the drive device housing or the transmission device housing, like the flange for connecting the end-side lid, typically encloses two rotational axes, which are defined by the central longitudinal axes of two partial cylinders; conversely, the two flange surfaces for the inlet and outlet enclose the corresponding inlet opening and outlet opening and are radially outside these two rotational axes, such that the cross-sections defined by these flange surfaces and corresponding to the inlet opening and outlet opening are preferably parallel to the rotational axis of the rotary piston defined by the central longitudinal axes of the partial cylinders. In particular, it is preferably the case that the planes in which the flange surfaces of the inlet opening and outlet opening are located are parallel to a plane (in which the two central longitudinal axes of the partial cylinders are located).

[0042] The invention also relates to a rotary piston pump having a housing in the manner described above and / or a rotary piston according to the first or second aspect of the invention.

[0043] Furthermore, the object of the invention is solved by a rotor for an eccentric screw pump, which rotor comprises:

[0044] - a rotor infrastructure, which rotor infrastructure comprises:

[0045] -- a hub structure having a support circumferential surface that extends around the rotational longitudinal axis of the rotor; and

[0046] -- a thread structure connected to the hub structure, which thread structure extends along the rotational longitudinal axis and which thread structure has:

[0047] --- an outer wall surface having a thread structure coiled around the rotational longitudinal axis; and

[0048] --- an inner wall surface that encloses a cavity, preferably a gas-filled cavity;

[0049] characterized in that the rotor infrastructure is manufactured partially or completely in an additive manufacturing method, in particular in a wire-based or powder-based surfacing method; and

[0050] - the thread structure is formed by a wall that extends in a curved manner and that has a substantially constant wall thickness, such that the inner wall surface extends substantially congruently radially inside the outer wall surface with reference to the rotational longitudinal axis, and the rotational axis extends in the cavity.

[0051] According to this embodiment, the rotor for an eccentric screw pump is manufactured by means of an additive manufacturing method. This aspect of the invention thus aims at the extrusion body of a positive-displacement pump in the same way as the rotary pistons according to the first and second aspects of the invention explained above. The rotor has an outer wall surface which has a thread structure. This thread structure is typically realized in the rotor for an eccentric screw pump by a rounded, single-threaded, double-threaded or multi-threaded external thread geometry which can rotate and roll in an eccentric rotary motion in the stator accordingly, the stator having an internal thread geometry adapted to the external thread geometry and having one more thread pitch than the rotor running in the stator. It is thus possible to achieve a flow through the stator in the axial direction along the stator longitudinal axis, wherein the inflow direction into the stator and the outflow direction out of the stator are preferably realized in the axial direction without a radial direction component. The rotor according to the invention is characterized by a substantially uniform wall thickness, so that a cavity is formed inside the rotor which contains the rotary longitudinal axis of the rotor and is delimited radially outwards by the inner wall surface of the rotor infrastructure. The inner wall surface extends substantially congruently with, i.e., approximately parallel to, the outer wall surface of the rotor. It is understood here that additional structures, such as ribs or other strengthening parts, can in particular be provided and applied to the inner wall surface in order to impart greater strength and stiffness to the rotor, provided that this is required for the application case.

[0052] By constructing the rotor in this way, a rotor which is particularly lightweight but at the same time very rigid due to the threaded configuration of the inner and outer wall surfaces is formed. In addition, the rotor can be variably configured in terms of its outer wall geometry in various ways due to the additive manufacturing method; thus, for example, a conically tapering rotor can also be manufactured, or a rotor can be manufactured in which the thread depth changes along the longitudinal axis such that the rotor can move in the stator with an eccentricity increasing or decreasing along the longitudinal axis.

[0053] Particularly preferred here is that the rotor basic structure is made of a metallic material and has a surface which is configured in such a way that an outer wall surface with a machining allowance is manufactured in an additive manufacturing method and this machining allowance is subsequently removed by a machining method until an external geometry corresponding to the nominal geometry of the rotor is obtained. According to this further formation, the machining allowance is applied to the outer wall surface and removed in a subsequent machining step by a machining method in order to thus manufacture the nominal geometry of the rotor. This removal in the machining method can be achieved in an indeterminate manner, for example by sanding, in order to achieve in this way a minor material removal and an improvement in the surface quality (reduction of roughness). The machining method can also be achieved by a CNC-controlled machining tool, for example by a multi-axis-guided grinding tool or milling tool or turning tool, in order to carry out the removal of the machining allowance. In this case, the geometry of the outer wall surface can also be precisely defined by the machining method.

[0054] In principle, it can be understood that the rotor according to the invention can also be provided with end faces or flange faces on the end sides. These end-side end faces or flange faces can be placed as prefabricated surfaces on the additively manufactured rotor basic structure and connected to this rotor basic structure, for example by welding. Alternatively, the end faces or flange faces can also be formed by an additive manufacturing method. The end faces or flange faces can partially or completely enclose the cavity such that the liquid conveyed in the eccentric screw pump cannot enter this cavity. Such end faces or flange faces are then also used to connect the rotor to the drive, for example as a flange for connecting the rotor to a rocking shaft.

[0055] Finally, the object according to the invention is also solved according to a fifth aspect of the invention by a stator for an eccentric screw pump, which stator comprises:

[0056] - a stator basic structure which extends along a stator longitudinal axis and which has:

[0057] -- an inner wall surface which has a thread geometry coiled around the stator longitudinal axis and which encloses a cavity, preferably a gas-filled cavity, in which the stator longitudinal axis extends; and

[0058] -- an outer wall surface;

[0059] wherein the stator basic structure is formed by a wall which extends curvedly with a substantially constant wall thickness, so that the outer wall surface extends substantially congruently radially outside the inner wall surface with reference to the stator longitudinal axis.

[0060] As already explained above in relation to the rotor, the stator for an eccentric screw pump has an inner wall surface which has a thread geometry coiled around the stator longitudinal axis. This inner wall surface can also form the direct contact surface with the rotor in a stator constructed entirely of metal, the rotor moving in an eccentrically guided rotational movement within the cavity surrounded by the inner wall surface. In such a case it is advantageous if the inner wall surface is machined in a machining method in order to thereby be brought into the nominal geometry. By such a machining method, a high surface quality can be achieved. However, usually, the inner wall surface of the stator is covered with a layer of a rubber-elastic material, and the inner surface of this elastomer layer then defines the nominal geometry of the stator and comes into contact with the rotor. In this case, the stator basic structure is dimensioned undersized, i.e. has a diameter dimension which is greater than the desired nominal internal geometry of the stator, and this undersizing is filled with elastomer material up to the desired nominal dimension when covering the inner wall surface.

[0061] The stator according to the invention has an outer wall surface which extends substantially congruently radially outside the inner wall surface, i.e. substantially parallel to the inner wall surface. Thus, the stator according to the invention can be constructed as a wall with a substantially constant wall thickness, which allows the stator basic structure to have a significantly reduced weight while having advantageous stiffness. The stator can preferably be constructed in one piece and thus the stator consisting of a plurality of annular segments can be dispensed with.

[0062] Particularly preferably, the stator basic structure is made of a metallic material. For metallic materials, on the one hand, different preferred manufacturing methods are available for the stator basic structure, such as casting methods and additive manufacturing methods, by means of which the metallic material is processed. In addition, metallic materials can be reworked well by machining methods, for example in order to thereby produce a better surface quality.

[0063] Particularly preferably, the stator base structure is manufactured partially or completely in an additive manufacturing method, in particular in a wire-based or powder-based surfacing method. Manufacturing the stator base structure in an additive manufacturing method allows, on the one hand, for the formation of a stator with inner and outer wall surfaces that are congruent with each other in a particularly efficient manner, and on the other hand, also enables the manufacturing of a specific thread structure with double or more threads of internal threads in an economical way through the additive manufacturing method. In particular, wire-based or powder-based surfacing methods are suitable for manufacturing the stator base structure. In this method, the wire or the supplied powder is melted in an electric arc and thus melted onto the stator base structure that has already been partially manufactured. The electric arc is triggered between the wire and the stator base structure that has already been partially manufactured or between a separate electrode and the stator base structure that has already been partially manufactured. Through this melting process, on the one hand, the wire material or powder material is selectively joined to the partially manufactured stator base structure, and on the other hand, it is firmly connected to the partially manufactured stator base structure. Thus, through such a surfacing method, the stator base structure can be manufactured selectively, precisely, and quickly.

[0064] It is further preferably that the wall of the stator base structure includes a metallic wall layer and a layer made of an elastomeric material. The metallic wall layer has an inner dimension deficiency, which is filled with the elastomeric material in a subsequent application method. The elastomeric material forms the rated geometric structure of the inner wall surface. According to this embodiment, the stator base structure is configured and prepared for covering its inner wall surface with an elastomeric material, as is typically implemented for the stator of an eccentric screw pump. The inner wall surface to which the elastomeric material is applied has a dimension deficiency, which means that this inner wall surface correspondingly has a larger diameter than the desired rated geometric structure of the inner wall surface of the completed stator. The rated geometric structure is achieved only by covering with the elastomeric material, and the rated geometric structure inside the stator is then formed by the inner wall surface of the elastomeric material covering layer.

[0065] The invention further includes an eccentric screw pump equipped with a rotor of the structural type described above, which is arranged parallel and eccentric to the stator longitudinal axis of the stator.

[0066] The invention further includes an eccentric screw pump equipped with a stator of the structural type described above, and a rotor is arranged parallel and eccentric to the stator longitudinal axis within the stator and inside the stator.

[0067] Finally, the invention further includes an eccentric screw pump which is equipped not only with a rotor of the construction type described above but also with a stator of the construction type described above. The eccentric screw pump constructed in this way allows, in a particularly advantageous manner, the stator and the rotor to be manufactured by an additive manufacturing method, with a corresponding undercut or overcut being specified, depending on whether a subsequent coating still needs to be applied or material removal needs to be carried out subsequently in a machining method.

[0068] The invention further relates to the use of an additive manufacturing device, in particular for wire-based or powder-based surfacing devices, for manufacturing, in an additive manufacturing device, a piston base structure of a rotary piston of a rotary piston pump in a build direction on a prefabricated hub, the build direction extending radially outwards with reference to the rotational axis of the hub; or for manufacturing, in an additive manufacturing device, a piston base structure of a rotary piston of a rotary piston pump in a build direction on a substrate, the build direction extending axially with reference to the rotational axis of the rotary piston; or for manufacturing, in an additive manufacturing device, a stator base structure of a stator of an eccentric screw pump in a build direction, the build direction extending axially with reference to the rotational axis of the rotary piston; in particular in such a way that, in the additive manufacturing device, a wall is manufactured which encloses a cavity, preferably a gas-filled cavity; and / or in the additive manufacturing device, a wall is manufactured which has a machining allowance relative to a nominal geometry, and this machining allowance is removed in a machining device after additive manufacturing so that the surface of the piston base structure is reduced to the nominal dimensions; and / or in the additive manufacturing device, a wall is manufactured which has a dimensional shortage relative to the nominal geometry, and this dimensional shortage is filled with an elastomeric material in a covering manufacturing after additive manufacturing up to the nominal geometry so that the piston base structure is wrapped with an elastomeric material or the stator base structure is lined with an elastomeric material. By means of this use, it is proposed that the additive manufacturing device be specifically used for manufacturing the rotary piston of a rotary piston pump or the stator of an eccentric screw pump, i.e. those components of a positive displacement pump typically made of two different materials, namely a material for the base structure (typically a metallic material) and an elastomeric covering layer (typically made of a rubber-elastic material). The additive manufacturing device is used in accordance with the invention in such a way that, with respect to the rotary piston thus manufactured, either the build direction is radial, i.e. starting from a prefabricated hub structure and extending radially outwards and thus producing the corresponding radially stacked layers of the rotary piston; or the build direction is axial, i.e. extending along the rotational axis of the rotary piston and thus also producing the layers of the rotary piston stacked on top of one another in the direction of the rotational axis. In this second case, the hub of the rotary piston can be manufactured in the additive manufacturing device. The rotary piston can, for example, in addition to the rotary piston vane structure, also have a terminal-side hub receiving structure in the form of an end face or a flange face into which the hub can be subsequently mounted in order to receive the rotary piston on or beside a shaft. As already explained above in relation to the rotor, such an end face or flange face can be placed on the additively manufactured piston base structure and connected thereto, for example welded. However, the hub structure can also be manufactured continuously integrally with the rotary piston vane structure in the additive manufacturing method.

[0069] According to the present invention, in a first aspect, a wall is manufactured in an additive manufacturing device, the wall enclosing a cavity, preferably a gas-filled cavity. Such a cavity can be formed, for example, in a rotary piston vane structure as explained above, or can be formed inside a rotary piston or inside a stator such that the rotary piston or the stator is configured as a hollow structure.

[0070] In this case, the cavity does not necessarily have to be completely closed, but an opening can be formed in the cavity, which opening is used, for example, in the case of the stator for receiving a rotor, or in the case of the rotary piston for receiving a hub or a drive shaft.

[0071] As an alternative or in addition, in the additive manufacturing method, a wall with a machining allowance can also be manufactured. Such a machining allowance is constituted by an additional material portion that exceeds the nominal geometry of the rotary piston or the stator and that can be removed in a subsequent machining process in order to thereby achieve a particularly high surface quality and a particularly high geometric accuracy, for example in order to thereby provide a connection surface, a sealing surface, and a bearing surface for other components of the rotary piston and the stator.

[0072] Furthermore, as an alternative or in addition, it is provided that a wall is manufactured in the additive manufacturing device, the wall having a dimensional deficiency. A dimensional deficiency can be understood in the context of the present invention as a material portion lacking relative to the nominal geometry, which material portion is filled in a subsequent machining step in order to achieve the nominal geometry. Typically, such a dimensional deficiency is provided to enable the setting of an elastomeric covering, for example an elastomeric covering made of a rubber-elastic material, and in this structural form, the typically rough surface manufactured by the additive manufacturing method is advantageously utilized in order to achieve a particularly good adhesion and a partial form-locking fixing effect of the elastomeric layer on the additively manufactured surface of the structure. However, in other application cases, the dimensional deficiency can also be filled with other materials to the nominal dimensions, for example in order to apply an anti-corrosion layer, an anti-wear layer, or in order to perform a layer application in a subsequent process, which layer application achieves a particularly high surface quality with low roughness or a particularly high geometric accuracy. Thus, for example, the dimensional deficiency can also be filled in a subsequent additive manufacturing process by means of selective additive material application.

[0073] The invention further includes the use of an additive manufacturing device, in particular the use of a wire-based or powder-based surfacing device, for manufacturing, in an additive manufacturing device, on a substrate in a build direction, a pump housing infrastructure of a rotary piston pump, the pump housing infrastructure having a wall with intersecting, partially cylindrical wall inner surfaces arranged within a pump chamber around two rotational axes, the build direction extending axially with reference to the two rotational axes; or for manufacturing, in an additive manufacturing device, on a substrate in a build direction, a rotor infrastructure of a rotor of an eccentric screw pump, the rotor infrastructure having a wall with a wall outer surface coiled around a rotational axis in a thread geometry, the build direction extending axially with reference to the rotational axis of the rotor; in particular in such a way that the wall inner surface of the wall manufactured in the additive manufacturing device encloses a cavity and the wall thickness of the wall remains substantially the same along the entire extent of the wall, such that the wall outer surface extends substantially parallel to the wall inner surface; and / or manufacturing a machining allowance on an inner wall surface or an outer wall surface in the additive manufacturing device and reprocessing, after additive manufacturing, the pump housing infrastructure manufactured in the additive manufacturing or the rotor infrastructure manufactured in the additive manufacturing in a machining device in order to cut away the machining allowance, and thus forming, from the pump housing infrastructure, the rated internal geometry of the pump housing and the rated geometry of the pump housing flange, or forming, from the rotor infrastructure, the threaded rated outer geometry of the rotor.

[0074] According to this application according to the invention, the additive manufacturing device is used in a defined manner for manufacturing the pump housing of a rotary piston pump or the rotor of an eccentric screw pump. This application thus relates to the manufacture of the following components of a positive displacement pump: the components typically do not include an elastomeric covering but are usually made of metallic materials. The use of the manufacturing device is realized in a specific way such that, according to an alternative application mode, a wall is manufactured which has a wall inner surface. The wall inner surface encloses a cavity and the wall thickness of the wall remains substantially the same along the entire extent of the wall. "Substantially the same extent" can be understood here to mean that the geometric extent of the outer wall at least partially also correspondingly identically imitates the inner wall surface, preferably the outer wall surface and the inner wall surface of the wall extend parallel to each other. Through such an application, a particularly lightweight and at the same time rigid structure of the rotary piston housing or the rotor is achieved. At the same time, the material consumption for manufacturing the rotary piston housing or the rotor is significantly reduced, which is achieved on the one hand by the specific geometry of the wall with a constant wall thickness and on the other hand by the additive manufacturing method in the additive manufacturing device, which in principle reduces or even completely avoids material losses caused by machining.

[0075] As an alternative or addition, the pump housing basic structure or the rotor basic structure can be manufactured in an additive manufacturing device with a machining allowance on the inner or outer wall surface, so that, as already explained above, the desired nominal geometry with high surface quality and high geometric accuracy can be manufactured by subsequently removing material. For this purpose, reference is made to the explanation of the machining allowance above, and it is understood that the machining allowance can be used, for example, to manufacture a flange surface for the drive device housing or for the lid of the pump housing; to manufacture the inner wall surface of the pump housing in sealing contact with the rotary piston; and to manufacture a flange connection surface for the drive shaft, or to manufacture a bearing surface or a sealing surface on the rotor; or to manufacture the external thread geometry of the rotor.

[0076] The invention further relates to a method for manufacturing an extruded body or a housing of a positive displacement pump, said extruded body or housing being, for example, a rotary piston of a rotary piston pump or a pump housing or a rotor or a stator of an eccentric screw pump, the method comprising the steps of:

[0077] - providing a build surface;

[0078] - building a body basic structure on the build surface in an additive manufacturing method, in particular in a wire-based or powder-based surfacing method;

[0079] It is characterized in that building the body basic structure comprises the steps of: building a curved wall of the extruded structure or the housing structure on the build surface and enclosing a cavity filled with gas with the curved wall.

[0080] The method according to the invention is characterized in that the extruded body or the housing of the positive displacement pump is manufactured in an additive manufacturing method, and in this case, the curved wall forming the extruded structure or the housing structure is built on the build surface and encloses a cavity. As already explained above, the curved wall can preferably have a substantially constant wall thickness. The cavity filled with gas can be a completely closed cavity, wherein the gas is thus enclosed during the manufacturing process in additive manufacturing and subsequently remains in the cavity. The cavity can also be an incompletely closed cavity, for example, the inner chamber of the housing or the stator. It is also possible to provide a plurality of cavities filled with gas. For example, a correspondingly closed cavity filled with gas can be provided in each rotary piston blade of the rotary piston, or a plurality of cavities filled with gas can be provided in the wall of the housing, so as to manufacture a rigid and at the same time lightweight structure with a small material consumption, and thus perhaps use these cavities for fluid flow in subsequent operation for cooling or heating the fluid conveyed by the positive displacement pump. The cavity can preferably be completely or more than half of its inner surface surrounded by the wall manufactured in the additive manufacturing method.

[0081] Particularly preferably, the main body infrastructure is manufactured in an additive manufacturing method, in particular in a wire-based or powder-based surfacing method, wherein the main body infrastructure has a prefabricated surface which corresponds to the nominal geometry of the extrusion body of the positive-displacement pump with a reprocessing tolerance, the reprocessing tolerance being a processing allowance or a dimensional shortage, and the prefabricated surface is reprocessed by applying or removing material with a thickness compensating the reprocessing tolerance, preferably additionally including a first reprocessing step in which the processing allowance on the circumferential surface is removed to the nominal dimension in a machining method; and / or preferably additionally including a second reprocessing step in which the prefabricated surface of the extrusion structure is covered with a layer made of an elastomeric material, the layer filling the dimensional shortage and having an external geometry corresponding to the nominal external geometry of the rotary piston or the nominal internal geometry of the stator. By this embodiment, the extrusion body or the housing is constructed in the axial direction - i.e. along the direction of the rotational axis defined by the extrusion body or the housing - in an additive manufacturing method. Here, the construction can be carried out line by line or layer by layer, the lines being drawn, for example, in a surfacing method, and the material layers produced by this line-by-line application then forming the applied layers. The material layers produced in this way are stacked on top of each other in the axial direction. Here, the guidance of the application device or the guidance of the hardening device is typically carried out multi-axially in an additive manufacturing method in order to selectively manufacture or harden a cross-section corresponding to the cross-section of the manufactured object in one plane and then to correspondingly harden or apply in a cross-section above this cross-section the material fraction corresponding to the cross-section of the manufactured object in this cross-section. The positions of these cross-sections thus correspond to the layer positions, and the planes of these cross-sections are thus perpendicular to the construction direction or perpendicular to the rotational axis of the extrusion body or the housing.

[0082] It is further preferably the case that the main body basic structure is manufactured in an additive manufacturing method, in particular in a wire-based or powder-based surfacing method, wherein the main body basic structure has a prefabricated surface which corresponds to the nominal geometry of the extrusion body of the positive-displacement pump with a reprocessing difference, the reprocessing difference being a machining allowance or a dimensional shortage, and the prefabricated surface is reprocessed by applying or removing material with a thickness compensating for the reprocessing difference. Preferably, it further includes a first reprocessing step in which the machining allowance on the circumferential surface is removed to the nominal dimension in a machining method; and / or preferably it further includes a second reprocessing step in which the prefabricated outer surface of the extrusion structure is covered with a layer made of an elastomeric material, the layer filling the dimensional shortage and having an outer geometry which corresponds to the nominal outer geometry of the rotary piston or the nominal inner geometry of the stator. According to this embodiment, the main body basic structure is manufactured in an additive manufacturing method, the main body basic structure having a geometry which is constructed as an outer geometry or an inner geometry with a reprocessing difference. Such a reprocessing difference can be a machining allowance or a dimensional shortage and is used to subsequently remove or apply material in subsequent machining steps in order to thus manufacture the nominal geometry. For this purpose, reference is made to the explanations given above for the machining allowance and the dimensional shortage.

[0083] The method according to the invention can preferably be used for manufacturing a rotary piston or a stator, wherein the main body basic structure has: a hub structure or a flange structure which has a circumferential surface that extends rotationally symmetrically about the axis of rotation of the extrusion body and which has a machining allowance; and an extrusion structure having at least two extrusion structures formed radially inside or outside the hub structure, these extrusion structures extending in the radial direction with reference to the axis of rotation and being spaced apart from one another in the circumferential direction, and these extrusion structures having a dimensional shortage on their prefabricated outer surfaces as a reprocessing difference. The reprocessing includes a first step in which the machining allowance on the circumferential surface is removed to the nominal dimension in a machining method; and the reprocessing includes a second step in which the prefabricated outer surface of the extrusion structure is covered with a layer made of an elastomeric material, the layer filling the dimensional shortage and having an outer geometry which corresponds to the nominal outer geometry of the rotary piston or the nominal inner geometry of the stator.

[0084] According to this further aspect, the method is used to manufacture components of a positive-displacement pump, which components should not only be subsequently covered with a second material, such as an elastomeric layer, but should also have joints, sealing surfaces or bearing surfaces, which are intended for the geometrically precise connection, sealing or bearing of a rotary piston or a stator to other components of the positive-displacement pump. Here, according to the invention, the additive manufacturing method is carried out in such a way that an additional machining amount is manufactured on the surface manufactured at this time, and this additional machining amount can thus be removed in a subsequent machining method in order to thus have the surface quality and geometric accuracy necessary for precise bearing / sealing or connection. In contrast, in other regions of the surface manufactured in the additive manufacturing method, an undercut amount is manufactured, and this undercut amount is filled with a second material, such as a rubber-elastic material, by covering in a subsequent manufacturing step up to the nominal geometry of the rotary piston or the stator. The thus desired rubber-elastic covering layer for the rotary piston or the stator can thus be effectively and reliably adhesively and partially form-fittingly connected to the base structure due to the favorable surface roughness from the additive manufacturing method. The method thus accordingly includes two reworking steps, in which this removal of the additional machining amount or this filling of the undercut amount is carried out.

[0085] It is furthermore preferred that the construction of the body base structure includes the steps of:

[0086] - constructing a body base structure having at least two piston vane structures and enclosing a gas-filled cavity with a curved wall in each piston vane structure;

[0087] - during a possible subsequent covering, the cavity remains free of elastomeric material.

[0088] According to this further aspect, when manufacturing the body base structure of a rotary piston, the cavity, preferably a gas-filled cavity, is enclosed by walls manufactured in an additive manufacturing method, and this gas-filled cavity remains free of elastomeric material during a possible subsequent covering method. By this further aspect, a rotary piston can be manufactured which is particularly light due to the gas-filled cavities contained therein, but in this case does not suffer a relevant loss of strength or stiffness. It is understood that such cavities can preferably be present in each piston vane structure, which cavities are accordingly closed in themselves. In certain embodiments, each piston vane structure can also have a cavity, and the cavities of the respective piston vane structures are interconnected.

[0089] According to a further preferred embodiment, the method is further configured such that when constructing the main body infrastructure, at least two piston vane structures are constructed, each piston vane structure being arranged at an angular offset from each other in the circumferential direction around the axis of rotation, and each piston vane structure having an envelope profile that extends in the radial direction from the piston vane root towards the piston vane head, the piston vane root being arranged adjacent to the circumferential surface and having a root width in the circumferential direction around the axis of rotation, the piston vane head having a head width in the circumferential direction around the axis of rotation, and the envelope profile between the piston vane root and the piston vane head having a piston vane neck that has a neck width in the circumferential direction around the axis of rotation, the neck width being less than the root width and preferably less than the head width. In this embodiment, the rotary piston has two piston vane structures, which are divided into a piston vane head, a piston vane root, and a piston vane neck therebetween. As already explained above, the three sections each approximately occupy 1 / 3 of the radial height of the piston vane. The piston vane neck forms a constriction in the circumferential direction compared to the piston vane root, and the width in the circumferential direction in the region of the piston vane neck is preferably also less than the width on the piston vane head, such that an hourglass shape of the piston vane structure is produced in a cross-section perpendicular to the axis of rotation of the rotary piston. This shape is advantageous for the mutual rolling of the piston vanes of two meshing rotary pistons, and according to this preferred embodiment, the piston basic structure already defines this shape of the rotary piston and thus ensures a coating, perhaps applied with a uniform layer thickness, to achieve the rated geometric structure of the rotary piston. It is further preferred here that when constructing the main body infrastructure, a cavity, preferably a gas-filled cavity, is enclosed in each piston vane structure, the cavity extending in the radial direction from the piston vane root towards the piston vane head, the piston vane root being arranged adjacent to the circumferential surface and having a root cavity width in the circumferential direction around the axis of rotation, the piston vane head having a head cavity width in the circumferential direction around the axis of rotation, and the cavity having a neck cavity width in the circumferential direction between the piston vane root and the piston vane head, the neck cavity width being less than the root cavity width and preferably less than the head cavity width. According to this embodiment, a cavity is formed inside the piston vane, the cavity having a smaller width in the circumferential direction in the piston vane neck compared to in the piston vane root, and preferably also having a smaller width compared to in the piston vane head. The cavity can thus conform to the corresponding external geometry of the piston vane, such that a substantially uniform wall thickness can be formed in the region of the piston vane, and at the same time a cavity that is maximized in terms of its volume is produced, which achieves the advantages of weight saving and material saving in the best possible way, without significantly affecting the stiffness and strength of the piston vane in this case.

[0090] The method can be further configured such that the main body infrastructure includes at least one extrusion structure, in particular two piston vane structures, and each extrusion structure has a wall which preferably encloses a cavity, in particular a gas-filled cavity, and the wall has a plurality of external construction ribs which are constructed on the wall in an additive manufacturing method, and the construction ribs preferably exist in a reworking tolerance configured as an underdimension. According to this embodiment, construction ribs are formed on the outer wall of each piston vane structure, and the construction ribs can also be integrally manufactured in an additive manufacturing method. These construction ribs are used to improve the connection with the elastomer layer applied to the rotary piston and to increase the resistance to shear forces which exist in the interface between the elastomer layer and the piston vane infrastructure, in such a way that a form-fitting support of the elastomer layer on the construction ribs is allowed. Here, the construction ribs preferably exist in a reworking tolerance configured as an underdimension. This can be understood as that the construction ribs define an envelope surface which abuts against the outer contour of the piston vane together with the construction ribs, and this envelope surface is at a defined underdimensioned distance from the nominal geometry of the piston. Thus, it is achieved that the applied elastomer layer everywhere has a layer thickness at least corresponding to the underdimension, and thus the desired degree of deformation of the elastomer layer is ensured in all regions of the elastomer layer.

[0091] Further preferably here, the construction ribs include a set of circumferential ribs which extend substantially along the circumferential direction on the wall, and the circumferential ribs preferably extend parallel to each other; and / or the construction ribs include one or more axial ribs which extend substantially along the axial direction with reference to the rotation axis; and / or the construction ribs include one or more axial-radial ribs which extend substantially along the circumferential-longitudinal direction of the vane, in particular spirally around the rotation axis along the vane extending at a lift angle. According to this embodiment, circumferential ribs, axial ribs and / or axial-radial ribs are formed, and they preferably exist in a reworking tolerance configured as an underdimension and thus define the minimum thickness of the elastomer layer. The circumferential ribs preferably can intersect with the axial ribs in such a way that the axial ribs extending in the axial direction intersect with the circumferential ribs extending in the circumferential direction. Through such intersection points, the stiffness of the rotary piston is significantly increased, and the fixation of the elastomer layer on the main body infrastructure of the rotary piston is improved. If a rotary piston with piston vanes extending spirally around the rotation axis is used, then the ribs can also extend as axial-radial ribs along the outer wall of such coiled vanes, which corresponds to a spiral extension path around the rotation axis of the piston.

[0092] The invention further relates to a method for manufacturing an extrusion body or a housing of a positive-displacement pump, for example the extrusion body or the housing is a rotary piston for a rotary piston pump or a pump housing or a rotor or a stator for an eccentric screw pump, and the method includes the steps:

[0093] - Provide a construction surface;

[0094] - Construct a main body infrastructure on the construction surface, the main body infrastructure having a prefabricated outer surface that corresponds to the external geometry of the extruded body with a reprocessing difference, the reprocessing difference being a machining allowance or a dimensional shortage;

[0095] - Reprocess the prefabricated outer surface by applying or removing material with a thickness that compensates for the reprocessing difference;

[0096] It is characterized in that the main body infrastructure is manufactured in an additive manufacturing method, especially in a wire-based or powder-based surfacing method, and the main body infrastructure has:

[0097] - A hub structure having a flange surface that extends rotationally symmetrically around the rotation axis of the extruded body, and the flange surface has a machining allowance. The reprocessing includes a first step in which the machining allowance on the flange surface is removed to a nominal dimension in a machining method; and

[0098] - An extrusion structure that coils around the rotation axis, and the extrusion structure has a radial machining allowance on its prefabricated outer surface as the reprocessing difference. The reprocessing includes a second step in which the machining allowance on the prefabricated outer surface is removed to a nominal dimension in a machining method; or

[0099] - An extrusion structure that coils around the rotation axis, and the extrusion structure has a radial dimensional shortage on its prefabricated outer surface as the reprocessing difference. The reprocessing includes a second step in which the dimensional shortage on the prefabricated outer surface is filled to a nominal dimension in a covering method.

[0100] According to the method of the present invention defined in this way, the extrusion body or the housing of the positive displacement pump is manufactured by an additive manufacturing method, and in this case, the reprocessing difference, which is the additional machining amount or the underdimension amount, is taken into account during manufacturing by the additive method. This additional machining amount is used for reprocessing in a machining method, so as to thus manufacture, for example, sufficient surface quality and sufficient geometric accuracy relative to the nominal geometry on a flange surface, which is used for sealing, supporting or connecting to other components of the positive displacement pump. The additional machining amount can also be provided on the extrusion structure of the extrusion body or the housing. As such an extrusion structure, in the sense of the present invention, the surface of the extrusion body or the housing should be understood, which surface is in contact with the fluid to be conveyed and provides a sealing action for conveying this fluid, that is, a structure with a surface is formed, and this surface is in a moving sealing contact between the extrusion body and the housing. Therefore, as the extrusion structure, the piston blades of a rotary piston, the thread structure of a rotor, the groove structure of a stator, and the inner surface defining the pump chamber of the housing of a rotary piston pump are understood. According to the present invention, either the additional machining amount or the underdimension amount can be provided on such an extrusion structure, which in the first case allows machining reprocessing to manufacture high surface quality and geometric accuracy, and in the second case allows covering with a second material, such as an elastomeric material, so as to thus manufacture, for example, a rotary piston covered with a rubber elastic layer or a stator lined with a rubber elastic layer.

[0101] Here, for the manufacture of a rotary piston, a stator or a rotor, it is preferred that the extrusion structure is preferably threaded and has a thread depth in the radial direction with reference to the axis of rotation. By such a threaded configuration, the mode of action of the rotor and stator of an eccentric screw pump is allowed, and it is allowed to convey with a rotary piston pump in a manner with reduced pulsation or without pulsation. The extrusion structure configured in a threaded manner can be understood here as an extrusion structure which is constituted by one or more threads and the thread grooves between the threads in a threaded manner, and they are coiled helically around the axis of rotation. The thread typically extends in the case of a rotor or a stator at a lead angle greater than 60°, which lead angle is defined as the angle between a direction (the direction along which the thread of the thread extends in the unwinding) and a baseline (the baseline is in a cross-section perpendicular to the axis of rotation). The thread can in particular be multi-start.

[0102] The method can be further configured in such a way that the construction of the main body infrastructure includes the steps of: constructing the extrusion structure as a curved wall on a construction surface and surrounding a cavity filled with a gas with the curved wall. Surrounding the cavity filled with a gas, which can be implemented as described above, allows a weight-saving and material-saving construction of the main body infrastructure.

[0103] It is further preferred that the method is further configured such that the build surface is the surface of the substrate, and the main basic structure is built layer by layer on the surface of the substrate in the direction of the axis of rotation of the extrusion body or the housing, and the axis of rotation is perpendicular to the surface of the substrate. In this further configuration, the main basic structure is built vertically on the build plate used as the substrate, so that the length of the main basic structure that can be achieved along the axis of rotation is not limited by the size of the substrate, but by the structural height available above the substrate in the additive manufacturing device. This build method allows the manufacture of a main basic structure with sufficient length for the manufacture according to the invention, for example, a rotor or a stator for an eccentric screw pump. The build-up achieved in this manufacturing method by applying the material layer by layer or line by line thus has layer boundaries between two adjacent layers, which are approximately perpendicular to the axis of rotation, i.e., approximately parallel to the cross-section around the axis of rotation.

[0104] It is also further preferred that build manufacturing data sets for controlling the building of the main basic structure in the additive manufacturing method are generated from the geometric nominal data of the extrusion body or the housing, and the building of the main basic structure is controlled by means of these build manufacturing data sets, and removal manufacturing data sets are created from the geometric nominal data and / or the build manufacturing data sets, and reprocessing is achieved by multi-axis milling, which is controlled by the removal manufacturing data sets. According to this embodiment, data sets are generated from the geometric nominal data of the extrusion body or the housing, which are used to control the process of the additive manufacturing method in the additive manufacturing device, and a second data set is created by means of the data sets thus generated for building manufacturing in the additive manufacturing method or by means of the geometric nominal data, which second data set is configured for removal manufacturing and describes the CAD-CAM data set, by means of which the subsequent removal of the machining allowance is achieved. By this direct derivation of manufacturing control data for the additive manufacturing method on the one hand and the cutting removal method on the other hand, a high geometric accuracy of the manufacturing is achieved in the additive manufacturing method and the cutting removal method. At the same time, it is allowed to construct the machining allowance as small as possible in order to minimize the volume to be cut, without the risk in this case that the machining allowance drops below the nominal dimension in the region of the geometric structure and thus no longer allows cutting reprocessing. In addition, the creation of the manufacturing data defined according to this further embodiment reduces the computational effort and storage capacity required for generating the manufacturing data sets required for the successive manufacturing steps of additive manufacturing and cutting removal.

[0105] Particularly preferably, the method is used for manufacturing a stator of an eccentric screw pump, and the method operates in the following steps: providing a construction surface; constructing a main body basic structure on the construction surface, the main body basic structure having a prefabricated outer surface which corresponds to the external geometry of the stator with a reprocessing difference, the reprocessing difference being a processing additional amount or a dimensional shortage amount; reprocessing the prefabricated outer surface by applying or removing material with a thickness compensating for the reprocessing difference; characterized in that the main body basic structure is manufactured in an additive manufacturing method, particularly in a wire-based or powder-based surfacing method, and the main body basic structure includes a curved wall having an inner wall surface and an outer wall surface, the curved wall extending in the axial direction with reference to a rotation axis, the inner wall surface surrounding the rotation axis and having at least two thread lines coiled around the rotation axis, the inner wall surface having a dimensional shortage amount as the reprocessing difference, and the prefabricated outer surface including a prepared flange surface having a processing additional amount as the reprocessing difference, the reprocessing including a first step in which the processing additional amount on the prepared flange surface is removed in a machining method until a rated dimension and thus the flange surface is manufactured, and the reprocessing including a second step in which the prefabricated outer surface of the piston vane structure is covered with a layer made of an elastomer material, the layer filling the dimensional shortage amount and having an external geometry corresponding to the rated geometry of the rotary piston.

[0106] Furthermore, if the method is used for manufacturing a pump housing of a rotary piston pump, then particularly preferably, the method operates in the following steps: providing a construction surface perpendicular to the rotation axis; constructing a main body basic structure on the construction surface, the main body basic structure having a prefabricated flange surface and a prefabricated inner wall surface which correspond to the flange surface and the inner wall surface of the pump housing with a reprocessing difference; reprocessing the prefabricated flange surface and the prefabricated inner wall surface by removing material with a thickness compensating for the reprocessing difference; characterized in that the main body basic structure is manufactured in an additive manufacturing method, particularly in a wire-based or powder-based surfacing method, and the main body basic structure includes a curved wall having a prefabricated inner wall surface and an outer wall surface, the curved wall extending in the axial direction with reference to the rotation axis, the prefabricated inner wall surface surrounding the rotation axis and having two partially cylindrical surfaces intersecting each other, the reprocessing including a first step in which the processing additional amount on the prefabricated flange surface is removed in a machining method until a rated dimension and thus the flange surface is manufactured, and the reprocessing including a second step in which the processing additional amount on the prefabricated inner wall surface is removed in a machining method until a rated dimension and thus the inner wall surface is manufactured.

[0107] In particular, according to this embodiment, the main body infrastructure, in particular the extruded body, the stator or the pump housing, extends along the manufacturing rotation axis. The provision of the building surface includes the provision of a substrate having a surface that forms the building surface. The construction of the main body infrastructure includes constructing the main body infrastructure on the surface. The surface is horizontally oriented and the main body infrastructure is constructed layer by layer on this surface in a vertically oriented construction direction that extends parallel to the manufacturing rotation axis, and the layers of the layer-by-layer constructed main body infrastructure are substantially perpendicular to the manufacturing rotation axis.

[0108] According to a further preferred embodiment, the method is further configured such that the wall is constructed as a double wall, the double wall including an inner wall having an inner wall surface and an outer wall having an outer wall surface, and at least one cavity, preferably a gas-filled cavity, is formed between the inner wall and the outer wall. Since the wall is thus constructed as a double wall, on the one hand, reinforcement is achieved, and on the other hand, weight-saving and material-saving manufacturing is achieved. The cavity can be retained as a cavity during the subsequent operation of the component and thus cause a reduction in the weight of the component. In another application mode, the cavity can be used to guide a fluid, such as a cooling liquid or a heating liquid, in order to achieve a cooling effect or a heating effect on the positive displacement pump.

[0109] Furthermore, in all embodiments of the method according to the invention (which produce cavities, preferably gas-filled cavities, in the additive manufacturing method), it is particularly preferred that one or more ribs are constructed when constructing the main body infrastructure, the ribs extending through the cavity in order to reinforce the wall structure around the cavity, preferably each cavity being reinforced by one or more ribs. By means of such ribs, the cavity can be divided into two completely separate cavities from each other, or divided by such ribs into a rib-reinforced, connected cavity with improved stiffness.

[0110] According to a further preferred embodiment, the additive manufacturing method is a wire-based or powder-based surfacing method, in which the material application is selectively achieved by melting a metal wire or powder by means of the geometric structure of the main body infrastructure, in particular in such a way that melting is continuously carried out along the weld bead, the extension direction of the weld bead being controlled by means of the geometric data of the main body infrastructure; and / or melting is achieved in an electric arc or a laser beam.

[0111] By means of this embodiment of the additive manufacturing method, an effective manufacturing of the main body infrastructure is achieved in the additive manufacturing method, and also for large main body infrastructures with dimensions greater than 1 m, rapid and highly load-bearing material construction is allowed. Here, the surfacing method allows the processing of different alternative metal materials and can thus well adapt to the strength requirements on the extruded body or the housing of the positive displacement pump.

[0112] Furthermore, it is preferred that in the additive manufacturing method, the material application head moves multi-axially relative to the build plane. Through the multi-axial movement of the material application head, on the one hand, it is preferably allowed for the material application head to move along the corresponding layer plane in which a layer of the main body infrastructure is manufactured. Additionally, 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. It is also preferred that the application head is pivotally supported and this pivoting movement is also part of the multi-axial movement of the application head. Through such pivotability, the positioning angle (at which the arc is triggered starting from the application head) can be improved such that the additive manufacturing of overhangs and overlaps is thereby also achieved, with overhangs and overlaps exceeding values such as 25° relative to the vertical direction that are common for the WAAM method. The multi-axial movement of the application head can in principle be understood in the sense of the present invention as a relative multi-axial movement between the substrate and the application head. In this sense, for example, one axis of movement of the multi-axial movement can also be provided by the rotation of the substrate.

[0113] The movement of the material application head and the rotation of the build plane about the manufacturing rotation axis are preferably controlled by means of control data derived from the geometric data of the main body infrastructure. Description of the Drawings

[0114] Preferred embodiments of the present invention are explained with the aid of the drawings. The drawings are as follows:

[0115] Figure 1 A partially transparent perspective view from the upper oblique side of a rotary piston pump according to a first embodiment of the present invention;

[0116] Figure 2 A schematic front view of two rotary pistons in a pump housing according to a second embodiment of the present invention shown in a cross-sectional view;

[0117] Figures 3a - 3c A perspective view and a partial cross-sectional view of a rotary piston according to a third embodiment of the present invention;

[0118] Figure 4 A schematic longitudinally sectioned side view of an eccentric screw pump according to a fourth embodiment of the present invention;

[0119] Figure 5 A schematic perspective view of a stator according to a fifth embodiment of the present invention; and

[0120] Figure 6 A schematic perspective view of a rotor according to a sixth embodiment of the present invention. Detailed Description of the Embodiments

[0121] First, reference is made to Figure 1, the basic structure of the rotary piston pump is as follows: In the pump housing 10, two rotary pistons 20, 21 rotate around two rotary axes 20', 21' extending parallel to each other. The rotary pistons have a plurality of rotary piston vanes 20a, b, c,... 21a, b, c,... that mesh with each other. The size of the volume contained between two adjacent rotary piston vanes of one rotary piston and the inner wall surface of the pump housing (the volume is decisively affected by the diameter, length, and axial spacing of the rotary piston), as well as the number of rotary piston vanes and the rotational speed of the rotary piston, determine the delivery volume of this rotary piston pump operating according to the positive displacement pump principle. Typically, in a series of designs of such a rotary piston pump, the length of the rotary piston along the rotary axis varies in order to increase the delivery volume under otherwise identical conditions. Correspondingly, the pump housing 10 is also configured to be correspondingly long in the direction of the rotary axis to match the selected length of the rotary piston.

[0122] At the first end, the pump housing 10 is closed by a lid 11, which is described transparently here and allows observation of the rotary piston for the purpose of description. The lid 11 is sealed and fixed to the flange surface 11' on the end side of the pump housing via a plurality of screws. The lid can be removed so that the rotary piston can then be taken out of the pump housing for maintenance or replacement purposes.

[0123] A side inlet opening 12 and a side outlet opening 13 opposite to the inlet opening are provided on the housing 10. The flow directions through the inlet opening 12 and the outlet opening 13 are radial with reference to the rotary axes 20', 21', and can also extend from the outlet opening to the inlet opening by reversing the rotation direction of the rotary piston. Preferably, the flow directions have no axial direction components.

[0124] Two rotary pistons 20, 21 are connected on the side facing the cover 11 to an upper and a lower drive shaft, which extend from the transmission housing 30 along the rotational axes 20', 21'. The transmission housing 30, like the cover 11, is connected to the pump housing via a flange 11'. The upper drive shaft is driven directly by the electric motor 40 or via a transmission. In the transmission housing, the driving force of the electric motor is transmitted to the lower drive shaft by means of a transmission coupling, and the rotational speeds of the two drive shafts are synchronized. Thus, the two rotary pistons are driven by the electric motor. In a further embodiment, it is also possible to dispense with the transmission synchronization, and for example the electric motor only directly drives one of the two rotary pistons. The other rotary piston then rotates via an engaged force transmission by the driven rotary piston. Again, in a further variant, each of the two rotary pistons can also be rotated directly by a drive motor. In such a case, for example instead of the cover 11, a drive device housing with an electric motor can also be provided, which directly drives the respective other rotary piston.

[0125] Figure 2 Shows a second embodiment of the invention. The rotary piston pump of this embodiment has two respectively four-vane rotary pistons 120, 121. Each rotary piston is fixed against torque on the drive shafts 131, 132 by means of a groove-tongue connection and rotates by the torque of these drive shafts. This rotation causes the squeezing of the liquid by the mutual engagement of the rotary pistons in the region between the two rotational axes 120', 121', and causes the liquid to be conveyed in the respective outer circumferential regions of the rotary pistons. Thus, the liquid is conveyed from the inlet opening 112 to the outlet opening 113, and the reverse conveyance can also be achieved by reversing the direction of rotation.

[0126] Each rotary piston slides sealingly on the inner circumferential surfaces 114, 115 of the pump housing 110 in the outer circumferential region. The pump housing is manufactured by a surfacing method and has a double wall with cavities 116, 117. The cavities are surrounded by an inner wall 116', 117' and an outer wall 116", 117". The cavities are filled with gas. It is understood that cooling liquid or heating liquid can be guided and circulated in the cavities 116, 117 during operation in order to achieve the cooling or heating of the pump and the cooling or heating of the medium conveyed in the pump, which can also be understood as cavities filled with gas according to the invention.

[0127] The inner circumferential surfaces 114, 115 are built with a machining allowance in the additive manufacturing method, and this machining allowance is subsequently removed by cutting in order to achieve a high surface quality and geometric accuracy of the inner circumferential surfaces. The circumferential surfaces then form two precise partial cylindrical surfaces around the rotational axes 120’, 121’, and thus a reliable seal of the piston blade tips sliding along the circumferential surface and a minimized wear of these piston blade tips can be achieved.

[0128] Flange surfaces 112’, 113’ are provided in the regions of the inlet opening 112 and the outlet opening 113, and these flange surfaces are used to sealingly connect the inlet pipe or the outlet pipe to the pump housing. A machining allowance is also manufactured in the additive manufacturing method in the regions of these flange surfaces 112’, 113’, and this machining allowance is subsequently removed by cutting in order to thereby produce a flat connection surface and to allow a sealing connection of the pipeline to the inlet opening or the outlet opening.

[0129] In Figure 2 the left - hand rotary piston is described as a rotary piston covered with rubber, while the right - hand rotary piston is configured as a fully metallic rotary piston. However, in principle, it can be understood that in a rotary piston pump, two rotary pistons of the same structural type are always used, i.e., one rubber - covered piston on each side or one fully metallic rotary piston on each side. In Figure 2 the mixed description is only used to better explain the possible embodiments of the present invention.

[0130] The left - hand rotary piston 121 has a body basic structure or piston basic structure, which is manufactured in the surfacing method as an additive manufacturing method. The rotary piston includes: a metallic piston basic structure 112, which in principle forms the shape of the rotary piston and includes four piston blades formed on the rotary piston; and a hub having an inner circumferential surface for connection to the drive shaft 132. The inner circumferential surface of the central hole of the piston basic structure (which is used for the connection and centering of the rotary piston on the drive shaft 132) is manufactured with a machining allowance in the additive manufacturing method, and this machining allowance is expanded to the nominal dimension defined by the manufacturing error either beforehand or subsequently in a cutting turning process in order to achieve the centering and almost clearance - free connection of the rotary piston on the drive shaft.

[0131] The piston basic structure 122 has a cavity 123a, b, c, d in each of the four piston blades, and these cavities are filled with gas and are completely and sealingly surrounded by the piston basic structure. These gas - filled cavities are used for material saving and weight reduction of the rotary piston.

[0132] The gas-filled cavities 123a, b, c, d have an hourglass shape, which includes a larger width in the circumferential direction on the piston vane roots and on the piston vane heads, and a constriction with a smaller width in the circumferential direction in the region of the piston vane neck between the piston vane head and the piston vane root. The outer geometry of each piston vane has a corresponding geometry, including a slight constriction in the region of the piston vane neck. In other embodiments, the piston vane can also be configured without such a constriction and extend linearly or taper towards the piston vane tip in the region of the piston vane neck.

[0133] The metallic piston base structure is covered on the outside 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 produced in an additive manufacturing method and can also possibly be cold-poured, for example. The elastomer layer 124 is configured with a substantially constant wall thickness along the entire rotary piston, which is achieved in such a way that the outer wall surface of the metallic piston base structure has predefined the desired nominal geometry of the rotary piston minus a dimensional deficiency. In some scenarios, a larger wall thickness of the elastomer layer can be provided at particularly load-bearing sites, for example in the head region of the piston vane. This dimensional deficiency is produced during the additive manufacturing process and corresponds to the desired wall thickness of the elastomer layer, which thus fills this dimensional deficiency up to the desired nominal outer dimension of the rotary piston.

[0134] The rotary piston 121 on the left is provided with rotary piston vanes extending in a threaded manner around the rotary axes 121’, 120’ in the same way as the rotary piston 120 on the right, such that the rotary piston vanes of the two rotary pistons engage with each other in the region between the two rotary axes in the manner of a screw drive and thus enable a reduced-pulsation or even pulsation-free conveyance of the medium. The lead angle of the threaded extension of the rotary piston is adapted here to the axial length of the rotary piston such that a conveyance chamber sealed by two blade tips abutting against the inner circumferential surface of the pump housing is maintained in each rotary position of the rotary piston. This means that the longer the rotary piston, the steeper the lead angle needs to be as the angle between a cross-section and the extension of a piston vane. Since an intermediate space that is self-enclosed is maintained between the two rotary piston vanes, a conveyance action is achieved, and the rotary piston pump is sealed against backflow in each rotary position.

[0135] The rotary piston 120 on the right side is configured as a metallic rotary piston having a metallic piston base structure which is formed on the one hand by an external multi-bent wall surface formed in an additive manufacturing method and on the other hand by an internal cylindrical wall surface, and these wall surfaces are connected to each other in the region of a recess between two piston blade tips. Thus, the piston base structure 125 of the rotary piston 120 on the right side directly forms the outer surface of the rotary piston, which outer surface meshes with another rotary piston (and thus in the actual application case with Figure 2 different, also a fully metallic rotary piston) and is in sealed sliding contact with the pump housing; and the piston base structure forms the inner cylindrical circumferential surface of the rotary piston, which cylindrical circumferential surface is fixed to the drive shaft. Both the outer surface of the rotary piston and the inner cylindrical circumferential surface of the rotary piston are manufactured in an additive manufacturing method with a machining allowance, which machining allowance is removed in a subsequent machining method in order to thereby produce a high surface quality and geometric accuracy of these surfaces.

[0136] The wall thickness of the piston base structure is substantially uniform, such that the outer surface of the rotary piston is formed by a multi-bent wall. This wall is delimited inwardly by a correspondingly identically extending inner bent wall surface. This inner bent wall surface encloses a cavity 126a, b, c, d filled with gas in each piston blade of the rotary piston 120. The cavity filled with gas is delimited radially inwardly by the wall structure of the piston base structure, which wall structure surrounds the inner cylindrical circumferential surface of the rotary piston. The cavities 126a, b, c,... filled with gas are in turn used for material saving and weight reduction of the rotary piston.

[0137] Now referring to Figures 3a - 3c , the third embodiment of the present invention is configured in the form of a four-blade rotary piston with a rubber-elastic covering layer. Figure 3b Shown here is the piston base structure, which includes a hub structure 210 and four radially extending piston blade structures 220a, b, c, d provided on the hub structure. The hub structure and the piston blade structures can be manufactured in an additive manufacturing method here, for example in such a way that the piston blade structures are constructed by successively stacking the individual layers in the direction of the rotational axis 200' of the rotary piston in a layer-by-layer manufacturing method. Alternatively, the hub structure 210 of the rotary piston can be prefabricated as a pipe section, and the outer circumferential surface of this pipe section serves as a construction surface for the four blade structures of the rotary piston. In this case, the four blade structures are respectively constructed layer by layer in the radial direction on the outer circumferential surface of the hub structure 210 in an additive manufacturing method.

[0138] Each piston vane structure 220a, b, c, d has a roof-shaped structure in cross-section, including an almost parallel extension direction of two wall surfaces in the vane root region and a gable-shaped extension direction of two wall surfaces towards the vane tip of the piston vane in the vane tip region of the piston vane. The piston vane structure hereby encloses a cavity 226 filled with gas in each rotary piston vane.

[0139] The piston vane structures 220a to d and the hub structure form a piston basic structure, as can be seen from Figure 3a , 3c The piston basic structure is covered with a rubber-elastic layer 224. The rubber-elastic layer 224 is applied directly to the piston vane structures 220a to d manufactured in an additive manufacturing method and thus adheres particularly well to the surface of these piston vane structures that is rough due to manufacturing, such that only a primer treatment is required before applying the rubber layer. The separate preparation or processing of this surface of the piston vane basic structure for improving the adhesion is therefore usually limited to cleaning and degreasing, or can be completely dispensed with without adversely affecting the adhesion of the rubber-elastic layer thereby.

[0140] The piston vane structure is constructed with an undersize on its outer surface in an additive manufacturing method, as already explained above, in order to thereby create the necessary space for covering with the rubber-elastic layer up to the nominal size.

[0141] Figure 4 Shows a third embodiment of the invention, which is configured as an eccentric screw pump. The eccentric screw pump has a stator 310 and a rotor 320 that rotates around a rotor longitudinal axis 320' in the stator. The outer circumferential surface of the rotor 320 is provided with a multi-threaded, steep, threaded structure with rounded threads and rolls in a multi-threaded internal threaded structure of the stator that is adapted to this threaded structure, and the internal threaded structure has one more thread than the outer threaded structure of the rotor. The rotor thus performs a movement of rotating around the stator central longitudinal axis 310', that is to say, the rotor rotates around its rotation axis, and the rotation axis 320' of the rotor rotates around the stator longitudinal axis.

[0142] The rotor 320 is connected to a rocking shaft 330 at the end of the stator on the inlet side, and the rocking shaft itself is connected to a drive motor 350 via a transmission 340. The rocking shaft drives the rotor by means of two universal joints 331, 332 for the eccentric rotational movement of the rotor.

[0143] The rotor 320 is formed by a bent wall which is manufactured in an additive manufacturing process. The wall encloses an internal gas-filled cavity 326 here. The fixing screw extends through this cavity from the outlet end of the rotor up to the flange connection surface, and the rotor is fixed to the cardan joint 331 on the left side of the rocking shaft by this flange connection surface. In the region of this flange connection surface for connection to the cardan joint, the rotor is manufactured in an additive manufacturing process with a machining allowance, and this machining allowance is removed to the nominal dimension in a subsequent machining process in order to thereby produce the necessary surface quality and geometric accuracy for the tapered connection to the cardan joint. The fixing screw 322 serves to apply a corresponding tensile force to this tapered connection and can be loosened by a helical movement at the outlet-side end of the rotor.

[0144] The stator 310 is also formed by a bent housing wall, and this wall also encloses a gas-filled cavity 316. In pump operation, the fluid to be conveyed and the rotor are arranged in the gas-filled cavity 316. The bent housing wall 311 of the stator has an internal geometry which corresponds to a multi-threaded stator thread structure. This inner surface can be manufactured in an additive manufacturing process with a machining allowance in order to subsequently produce a geometrically precise surface by a machining manufacturing process and thereby produce a pure-metal stator. However, preferably, the inner surface of the stator basic structure is manufactured in an additive manufacturing process with an undersize, and this undersize is filled to the internal nominal dimension by lining the inside with a rubber-elastic material in a subsequent covering process. The elastomer covering layer in the inner chamber of the stator can be formed with a substantially uniform wall thickness, since the metal stator basic structure has already geometrically provided the thread geometry of the multi-threaded inner thread of the stator in the additive manufacturing process.

[0145] The wall thickness of the stator basic structure is substantially uniform, such that the multi-threaded thread structure is also profiled on the outer circumferential surface of the stator. The stator is thus not provided with a cylindrical circumferential surface on the outside, but rather with a multi-threaded external thread surface. This construction results in material savings and an increase in stiffness of the stator.

[0146] The stator is provided with end-side flange surfaces 311, 312 on the inlet side as well as on the outlet side, and these flange surfaces are manufactured, for example, in an additive manufacturing process with a machining allowance in order to achieve, by mechanical reworking, sufficient surface quality and geometric accuracy for a sealing connection to the inlet housing or the outlet housing. However, alternatively, the flange surfaces can also be formed by a base plate on which the stator is constructed, or can be connected to the stator as a prefabricated plate afterwards. The stator is flowed through axially.

[0147] The rocking shaft 330 rotates in an inlet housing having an inlet opening 333. An outlet housing 360 is fixed sealingly to the outlet end of the stator 310, and this outlet housing has an outlet opening 363.

[0148] Figure 5 Schematically shows a stator infrastructure manufactured in an additive manufacturing method. Starting from the build plane 410, the stator infrastructure extends as a curved wall surface that, in the vertical direction, forms a multi-threaded, threaded extension with rounded threads along the inner and outer surfaces within the central longitudinal axis 410'. The stator infrastructure is built in the vertical direction along the central longitudinal axis 410', thus creating a layer structure that is schematically defined by layer boundaries 411a, b, c, … in Figure 5 as described. These layer boundaries are approximately perpendicular to the central longitudinal axis 410' in cross-section. At the end sides, the stator infrastructure is provided with a flange 411, 421 each for connection to the outlet housing or the inlet housing of an eccentric screw pump. As can be seen at the upper end, the internal cavity has an elliptical cross-section that is determined by the double-threaded construction of the threads of this stator. In Figure 5 the stator described changes its cross-sectional profile, changing from a circular cross-section on the inlet side to an ellipse and back to a circular cross-section on the outlet side. Due to the circular cross-sections on the inlet and outlet sides, it is convenient to connect the stator to the existing inlet and outlet flanges. In this construction, it is possible to dispense with the insertion of a cover layer or a flange plate. In principle, it can be understood that a three-threaded, four-threaded or more-threaded thread construction can also be implemented on the stator. In this case, openings are formed at the ends of the stator in a corresponding manner in the form of a rounded triangle, a rounded quadrilateral or a plum blossom, or openings are formed in the form of a rounded polygon.

[0149] Figure 6 Shows a schematic diagram of a rotor infrastructure for an eccentric screw pump. The rotor infrastructure is configured as a curved wall structure that has a threaded extension with a single-thread on its outer and inner surfaces. The rotor thus corresponds to a tube with a circular cross-section that has a helical extension along its central longitudinal axis. As already described with respect to Figure 5Explained with respect to the stator, the rotor basic structure can also be constructed vertically on a construction surface not described here, where the layers are stacked on top of each other in the direction of the rotor longitudinal axis 520'. It can be understood here that this stacking can be achieved such that in the surfacing method, the wall structure of the rotor is manufactured by spirally moving the surfacing head around the central longitudinal axis of the rotor. Thereby, spirally extending layer boundaries are produced, which are schematically represented by the lines 511a, b, c. The rotor is manufactured in an additive manufacturing method with a machining allowance on its outer circumferential surface and on the annular surfaces 511, 521 at its two end sides, and this machining allowance is removed to the nominal dimensions in a subsequent machining method in order to manufacture a high surface quality and accuracy. The rotor has a wall thickness that remains essentially the same and encloses a cavity 526 filled with gas in its inner chamber, which cavity holds the filling gas during operation and thus enables significant weight and material savings. The cavity filled with gas can be used to accommodate fixing screws for fixing the rotor on the rocking shaft, or for inserting long tools that are used to fix and loosen screws at the end of the inlet side of the rotor, which tools fix the rotor on the rocking shaft or on the hinge of the rocking shaft.

[0150] List of reference numerals

[0151] 10 Pump housing

[0152] 11 Cover

[0153] 11’ Flange

[0154] 12 Inlet opening

[0155] 13 Outlet opening

[0156] 20, 21 Rotary pistons

[0157] 20a, b, c…, 21a, b, c… Rotary piston blades

[0158] 20’, 21’ Axis of rotation

[0159] 30 Transmission housing

[0160] 40 Electric motor

[0161] 110 Pump housing

[0162] 112 Inlet opening

[0163] 113 Outlet opening

[0164] 112’, 113’ Flange surfaces

[0165] 114, 115 Inner circumferential surfaces

[0166] 116, 117 Cavities

[0167] Inner walls of 116’ and 117’

[0168] Outer walls of 116” and 117”

[0169] Rotary piston on the right side of 120

[0170] Rotary piston on the left side of 121

[0171] Rotary pistons of 120 and 121 with blades

[0172] Rotary axes of 120’ and 121’

[0173] Piston basic structure of 122

[0174] Cavities of 123a, b, c

[0175] Elastomer layer of 124

[0176] Piston basic structure of 125

[0177] Drive shafts of 125 and 126

[0178] Gas-filled cavities of 126a, b, c…

[0179] Drive shaft of 132

[0180] Rotary axis of 200’

[0181] Hub structure of 210

[0182] Piston blade basic structures of 210 and 220a~d

[0183] Rotor of 220

[0184] Rotary axis of 220’

[0185] Piston blade structures of 220a, b, c, d

[0186] Rubber elastic layer of 224

[0187] Gas-filled cavity of 226

[0188] Stator of 310

[0189] Curved housing wall of 311

[0190] Rotor of 320

[0191] Gas-filled cavity of 321

[0192] Longitudinal axis of rotor of 320’

[0193] Fixing screw of 322

[0194] Rocking shaft of 330

[0195] 331,332 universal joint

[0196] 334 inlet opening

[0197] 340 transmission

[0198] 350 drive motor

[0199] 360 outlet housing

[0200] 363 outlet opening

[0201] 400' stator center longitudinal axis

[0202] 410 construction surface

[0203] 411a, b, c... layer boundaries

[0204] 412 flange

[0205] 520' rotor longitudinal axis

[0206] 511a, b, c... lines

[0207] 526 cavity

Claims

1. A rotary piston for a rotary piston pump, said rotary piston comprising: - A piston basic structure, said piston basic structure comprising: -- A hub structure, said hub structure having a supporting circumferential surface which extends around the rotational axis of the rotary piston; and - At least two piston vane structures connected to the hub structure, wherein said piston basic structure is made of a first material, preferably a metallic material, and is preferably radially externally wrapped with a second material different from the first material, especially an elastomeric material; characterized in that in the piston vane structure, preferably in each piston vane structure, at least one cavity, preferably a gas-filled cavity, is correspondingly formed, said cavity being surrounded by the piston vane wall of the piston basic structure and optionally by the outer circumferential surface of the hub structure, and said cavity being free of elastomeric material.

2. The rotary piston according to claim 1, characterized in that said piston vane structure is partially or completely made in an additive manufacturing method, preferably built on the outer circumferential surface of the hub structure in a radial build direction with reference to the rotational axis.

3. The rotary piston according to claim 1 or 2, characterized in that one or more ribs which extend through said cavity, preferably one or more ribs extend through each cavity.

4. The rotary piston according to any one of the above claims, characterized in that each piston vane structure among said at least two piston vane structures has: - A piston vane wall, preferably said piston vane wall surrounds said cavity in the piston vane structure; and - A plurality of build ribs provided on the piston vane wall outside said cavity, preferably said build ribs are manufactured in one or the same additive manufacturing method.

5. The rotary piston according to claim 4, characterized in that said build ribs comprise: - One or more circumferential ribs which extend on the piston vane wall substantially along the circumferential direction with reference to the rotational axis, and preferably said circumferential ribs extend parallel to each other; and / or - One or more axial ribs which extend substantially along the axial direction with reference to the rotational axis; and / or - One or more radial ribs which extend substantially along the radial direction with reference to the rotational axis; and / or - One or more axial-radial ribs which extend along the circumferential-longitudinal direction of the vane, especially helically around the rotational axis along a vane extending at a lift angle.

6. A rotary piston for a rotary piston pump, said rotary piston comprising: - A piston basic structure, said piston basic structure comprising: -- A hub structure, said hub structure having a supporting circumferential surface which extends around the rotational axis of the rotary piston; and -- At least two piston vane structures connected to the hub structure, wherein said piston basic structure is made of a first material, preferably a metallic material, and is preferably radially externally wrapped with a second material different from the first material, especially an elastomeric material; characterized in that said piston basic structure is partially or completely manufactured in an additive manufacturing method, especially in a wire- or powder-based surfacing method; and - The second material fills a dimension shortage of the piston base structure, and the second material has an external geometry corresponding to the rated geometry of the rotary piston.

7. The rotary piston according to any one of claims 1 or 3 to 6 above, characterized in that the piston base structure is constructed in an additive manufacturing method with reference to the rotational axis in a radial build direction or in an axial build direction.

8. The rotary piston according to claim 6 or 7, characterized in that at least one cavity, preferably a gas-filled cavity, is formed correspondingly in the piston vane structure, preferably in each piston vane structure. The cavity is surrounded by the piston vane wall of the piston base structure and perhaps by the outer circumferential surface of the hub structure, and the cavity has no elastomeric material. Preferably, the piston base structure has an outer wall with an outer wall surface and an inner wall surface, and the cavity is radially inside the inner wall surface with reference to the rotational axis. Additionally preferably, the rotational axis is in the cavity.

9. A pump housing for a rotary piston pump, the pump housing comprising: a body base structure, the body base structure including an outer wall manufactured in an additive selective application method, wherein the material forming the outer wall is discharged layer by layer along one or more trajectories by a multi-axis moving application head and thus the outer wall is constructed; - wherein the outer wall is a curved wall having an outer wall surface and an inner wall surface, and the curved wall has a surface mechanically manufactured in a machining manufacturing method in the form of two intersecting partial cylindrical surfaces. The surface is manufactured in such a way that in the additive selective application method, a machining additional amount is applied as a reworking difference so that the geometric dimension exceeds the rated geometry of the inner wall surface, and the material is removed by a thickness compensating for the reworking difference in a subsequent machining method to form the surface of the inner wall surface; - wherein the body base structure further includes a flange surface having a flange surface mechanically manufactured in a machining manufacturing method. The flange surface is manufactured in such a way that in the additive selective application method, a machining additional amount is applied as a reworking difference so that the geometric dimension exceeds the rated geometry of the flange surface, and the material is removed by a thickness compensating for the reworking difference in a subsequent machining method to form the flange surface, wherein preferably, the application head moves along a trajectory section extending transversely to the inner wall surface of the wall, especially at an angle of 50° to 90° to the inner wall surface.

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

11. A rotor for an eccentric screw pump, the rotor comprising: - a rotor base structure, the rotor base structure including: -- a hub structure having a support circumferential surface extending around the rotational longitudinal axis of the rotor; and --A threaded structure connected to the hub structure, the threaded structure extending along a rotational longitudinal axis, and the threaded structure having: ---An outer wall surface having a threaded structure coiled around the rotational longitudinal axis; and ---An inner wall surface surrounding the cavity; It is characterized in that the rotor basic structure is partially or completely manufactured in an additive manufacturing method, in particular in a wire-based or powder-based surfacing method; and -The threaded structure is formed by a wall extending in a curved manner, the wall having a substantially constant wall thickness, so that the inner wall surface extends substantially congruently and radially inside the outer wall surface with reference to the rotational longitudinal axis, and the rotational axis extends in the cavity.

12. The rotor according to claim 11, characterized in that the rotor basic structure is made of a metallic material and has a surface configured in such a way that an outer wall surface with a machining allowance is manufactured in an additive manufacturing method, and the machining allowance is subsequently removed by a machining method until an external geometry corresponding to the rated geometry of the rotor.

13. A stator for an eccentric screw pump, the stator comprising: -A stator basic structure extending along a stator longitudinal axis, and the stator basic structure having: --An inner wall surface having a threaded geometry coiled around the stator longitudinal axis, and the inner wall surface surrounding a cavity, the stator longitudinal axis extending in the cavity; and --An outer wall surface; It is characterized in that the stator basic structure is formed by a wall extending in a curved manner with a substantially constant wall thickness, so that the outer wall surface extends substantially congruently and radially outside the inner wall surface with reference to the stator longitudinal axis.

14. The stator according to claim 13, wherein the stator basic structure is made of a metallic material.

15. The stator according to claim 13 or 14, characterized in that the stator basic structure is partially or completely manufactured in an additive manufacturing method, in particular in a wire-based or powder-based surfacing method.

16. The stator according to claim 15, characterized in that the wall of the stator basic structure comprises a metallic wall layer and a layer made of an elastomeric material, the metallic wall layer having an inner dimensional deficiency that is filled with the elastomeric material in a subsequent application method, and the elastomeric material forms the rated geometry of the inner wall surface.

17. The stator according to any one of claims 13 - 16 above or the rotor according to any one of claims 11 - 12 above, characterized in that the stator or rotor extends from a starting cross-section at one end side to an end cross-section at an opposite end side, and an intermediate section with an intermediate cross-section is provided between the starting cross-section and the end cross-section, the intermediate cross-section having a profile different from a circular cross-section, in particular having an elliptical, triangular or four-petal plum blossom profile, and additionally, -The starting cross-section has a circular profile, and / or -The end cross-section has a circular profile.

18. An eccentric screw pump, comprising a rotor according to any one of claims 11-12 and / or a stator according to any one of claims 13-15, wherein a longitudinal axis of the rotor is parallel and eccentrically arranged with respect to a longitudinal axis of the stator; an application of an additive manufacturing device, in particular a wire-based or powder-based surfacing device, for: - manufacturing, in an additive manufacturing device, a piston basic structure of a rotary piston of a rotary piston pump on a prefabricated hub in a build direction, the build direction extending radially outwardly with reference to a rotational axis of the hub ； or - manufacturing, in an additive manufacturing device, a piston basic structure of a rotary piston of a rotary piston pump on a substrate in a build direction, the build direction extending axially with reference to a rotational axis of the rotary piston; or - manufacturing, in an additive manufacturing device, a stator basic structure of an eccentric screw pump in a build direction, the build direction extending axially with reference to a rotational axis of the rotary piston; in particular in the following manner: - manufacturing, in an additive manufacturing device, a wall that encloses a cavity, preferably a gas-filled cavity; and / or - manufacturing, in an additive manufacturing device, a wall having a machining allowance with respect to a nominal geometry, and the machining allowance is removed in a machining device after additive manufacturing so that a surface of the piston basic structure is reduced to the nominal size; and / or - manufacturing, in an additive manufacturing device, a wall having a dimensional deficiency with respect to a nominal geometry, and the dimensional deficiency is filled with an elastomeric material in a covering device up to the nominal geometry after additive manufacturing so that the piston basic structure is wrapped with the elastomeric material or the stator basic structure is lined with the elastomeric material.

19. An application of an additive manufacturing device, in particular a wire-based or powder-based surfacing device, for: - manufacturing, in an additive manufacturing device, a pump housing basic structure of a rotary piston pump on a substrate in a build direction, the pump housing basic structure having a wall with intersecting, partially cylindrical wall inner surfaces arranged around two rotational axes within a pump chamber, the build direction extending axially with reference to the two rotational axes ； or - manufacturing, in an additive manufacturing device, a rotor basic structure of an eccentric screw pump on a substrate in a build direction, the rotor basic structure having a wall with a wall outer surface coiled around a rotational axis in a thread geometry, the build direction extending axially with reference to a rotational axis of the rotor; in particular in the following manner: - a wall inner surface of the wall manufactured in the additive manufacturing device encloses a cavity, preferably a gas-filled cavity, and a wall thickness of the wall remains substantially the same along an entire extension of the wall, so that the wall outer surface extends substantially parallel to the wall inner surface; and / or -Manufacture a machining allowance on the inner wall surface or outer wall surface in an additive manufacturing device, and reprocess the pump housing basic structure manufactured in the additive manufacturing or the rotor basic structure manufactured in the additive manufacturing in a machining device after the additive manufacturing, so as to cut off the machining allowance, and thus form the rated internal geometry of the pump housing and the rated geometry of the pump housing flange from the pump housing basic structure, or form the threaded rated external geometry of the rotor from the rotor basic structure.

20. A method for manufacturing an extruded body or a housing of a positive displacement pump, for example, the extruded body or the housing is a rotary piston or a pump housing for a rotary piston pump or a rotor or a stator for an eccentric screw pump, the method comprising the steps of: -Providing a build surface; -In an additive manufacturing method, especially in a wire-based or powder-based surfacing method, building a body basic structure on the build surface; Characterized in that, Building the body basic structure includes the steps of: building a bounding wall of an extruded structure or a housing structure on the build surface, which defines an internal cavity, preferably a cavity filled with gas, and surrounding the cavity filled with gas with the bounding wall.

21. The method according to claim 20, Characterized in that, The extruded body or the housing is made by building layers in a layer-by-layer manufacturing method, and the layers are stacked on top of each other along a direction corresponding to the rotation axis, and the extruded body or the extruded body arranged in the housing rotates around the rotation axis during operation.

22. The method according to claim 20 or 21, Characterized in that, The body basic structure is manufactured in an additive manufacturing method, especially in a wire-based or powder-based surfacing method, -Wherein, the body basic structure has a prefabricated surface, the prefabricated surface corresponds to the rated geometry of the extruded body of the positive displacement pump with a reprocessing difference, the reprocessing difference is a machining allowance or a dimensional shortage, and the prefabricated surface is reprocessed by applying or removing material with a thickness compensating for the reprocessing difference, -Preferably further including a first reprocessing step, in the first reprocessing step, the machining allowance on the circumferential surface is removed to the rated size in a machining method, and / or -Preferably further including a second reprocessing step, in the second reprocessing step, the prefabricated outer surface of the extruded structure is covered with a layer made of an elastomeric material, the layer fills the dimensional shortage and has an external geometry corresponding to the rated external geometry of the rotary piston or the rated internal geometry of the stator.

23. The method according to claim 22, for manufacturing a rotary piston or a stator, Characterized in that, The body basic structure has: -A hub structure or a flange structure, the hub structure or the flange structure has a circumferential surface, the circumferential surface extends rotationally symmetrically around the rotation axis of the extruded body, and the circumferential surface has a machining allowance; - An extrusion structure having at least two extrusion structures formed radially inside or outside the hub structure, the extrusion structures extending in the radial direction with reference to the axis of rotation and being spaced apart from each other in the circumferential direction, and the extrusion structures having a dimensional shortage as a reworking difference on their prefabricated outer surfaces; wherein: - The reworking includes a first step in which the machining allowance on the circumferential surface is removed by a machining method until the rated dimension; and - The reworking includes a second step in which the prefabricated outer surface of the extrusion structure is covered with a layer made of an elastomeric material, the layer filling the dimensional shortage and having an outer geometry corresponding to the rated outer geometry of the rotary piston or the rated inner geometry of the stator.

24. The method according to any one of claims 20 - 23 above, characterized in that the construction of the main body basic structure includes the steps of: - Constructing a main body basic structure having at least two piston vane structures and enclosing a cavity filled with gas in each piston vane structure with a curved wall; - During a possible subsequent covering, the cavity filled with gas preferably remains free of elastomeric material.

25. The method according to any one of claims 20 - 24 above, characterized in that when constructing the main body basic structure, at least two piston vane structures are constructed, the piston vane structures being arranged at an angle offset from each other in the circumferential direction around the axis of rotation, and each piston vane structure having an envelope profile that extends in the radial direction from the vane root towards the vane head, the vane root being arranged adjacent to the circumferential surface and having a root width in the circumferential direction around the axis of rotation, the vane head having a head width in the circumferential direction around the axis of rotation, the envelope profile between the vane root and the vane head having a vane neck, the vane neck having a neck width in the circumferential direction around the axis of rotation, the neck width being less than or equal to the root width, and preferably the head width being less than or greater than the neck width.

26. The method according to claim 25, characterized in that when constructing the main body basic structure, a cavity, preferably a cavity filled with gas, is enclosed in each piston vane structure, the cavity extending in the radial direction from the vane root towards the vane head, the vane root being arranged adjacent to the circumferential surface and having a root cavity width in the circumferential direction around the axis of rotation, the vane head having a head cavity width in the circumferential direction around the axis of rotation, and the cavity having a neck cavity width in the circumferential direction between the vane root and the vane head, the neck cavity width being less than or equal to the root cavity width, and preferably the head cavity width being less than or greater than the neck cavity width.

27. The method according to any one of claims 20 - 26 above, characterized in that The main body infrastructure includes at least one extrusion structure, in particular two piston vane structures, and each extrusion structure has a wall, preferably the wall encloses a cavity, in particular a cavity filled with gas, and the wall has a plurality of external construction ribs, which are constructed on the wall in an additive manufacturing method, and the construction ribs preferably exist in the reprocessing difference configured as an undersize.

28. The method according to claim 27, wherein, the construction ribs include a set of circumferential ribs, the circumferential ribs extend substantially along the circumferential direction on the wall, and preferably the circumferential ribs extend parallel to each other; and preferably the construction ribs include one or more axial ribs, the axial ribs extend substantially along the axial direction with reference to the rotation axis.

29. A method for manufacturing an extrusion body or a housing of a positive-displacement pump, for example, the extrusion body or the housing is a rotary piston of a rotary piston pump or a pump housing or a rotor or a stator of an eccentric screw pump, the method comprising the steps of: - providing a construction surface; - constructing a main body infrastructure on the construction surface, the main body infrastructure having a prefabricated outer surface, the prefabricated outer surface corresponding to the external geometry of the extrusion body with a reprocessing difference, the reprocessing difference being a machining allowance or an undersize; - reprocessing the prefabricated outer surface by applying or removing material with a thickness compensating for the reprocessing difference; wherein, the main body infrastructure is manufactured in an additive manufacturing method, in particular in a wire-based or powder-based surfacing method, and the main body infrastructure has: - a hub structure, the hub structure having a flange surface, the flange surface extending rotationally symmetrically around the rotation axis of the extrusion body, and the flange surface having a machining allowance, and the reprocessing includes a first step, in which the machining allowance on the flange surface is removed until the nominal size in a machining method; and - an extrusion structure, the extrusion structure coiling around the rotation axis, and the extrusion structure having a radial machining allowance on its prefabricated outer surface as a reprocessing difference, and the reprocessing includes a second step, in which the machining allowance on the prefabricated outer surface is removed until the nominal size in a machining method; or - an extrusion structure, the extrusion structure coiling around the rotation axis, and the extrusion structure having a radial undersize on its prefabricated outer surface as a reprocessing difference, and the reprocessing includes a second step, in which the undersize on the prefabricated outer surface is filled until the nominal size in a covering method.

30. The method according to claim 29, wherein, the extrusion structure is preferably thread-shaped and has a thread depth in the radial direction with reference to the rotation axis.

31. The method according to claim 29 or 30, wherein, the construction of the main body infrastructure includes the steps of: - constructing the extrusion structure on the construction surface as a bounding wall defining an internal cavity, preferably a cavity filled with gas, and enclosing the cavity filled with gas with the bounding wall.

32. The method according to any one of the above claims 29 to 31, wherein, - The building surface is the surface of the substrate, and the main body infrastructure is built layer by layer on the surface of the substrate in the direction of the axis of rotation of the extruder or housing, and the axis of rotation is perpendicular to the surface of the substrate.

33. The method according to any one of the preceding claims 29 to 32, characterized in that - Build manufacturing data sets for controlling the construction of the main body infrastructure in the additive manufacturing method are generated from the geometric rated data of the extruder or housing, and the construction of the main body infrastructure is controlled by means of the build manufacturing data sets; and - Removal manufacturing data sets are created from the geometric rated data and / or the build manufacturing data sets, and the reprocessing is achieved by multi-axis milling, which is controlled by the removal manufacturing data sets.

34. A method for manufacturing a stator of an eccentric screw pump, the method comprising the steps of: - Providing a building surface; - Building a main body infrastructure on the building surface, the main body infrastructure having a prefabricated outer surface that corresponds to the external and internal geometries of the stator with a reprocessing difference, the reprocessing difference being a machining allowance or a dimensional shortage; - Reprocessing the prefabricated outer surface by applying or removing material with a thickness that compensates for the reprocessing difference; characterized in that the main body infrastructure is manufactured in an additive manufacturing method, in particular in a wire-based or powder-based surfacing method, and the main body infrastructure comprises: -- A curved wall having an inner wall surface and an outer wall surface, the curved wall extending in the axial direction with reference to the axis of rotation, wherein --- The inner wall surface encloses the axis of rotation and has at least two thread lines that coil around the axis of rotation, --- The inner wall surface has a dimensional shortage as the reprocessing difference, and --- The prefabricated outer surface includes a prepared flange surface that has a machining allowance as the reprocessing difference; - The reprocessing includes a first step in which the machining allowance on the prepared flange surface is removed in a machining method until the rated size and thus the flange surface is manufactured; and - The reprocessing includes a second step in which the inner wall surface is covered with a layer made of an elastomeric material, the layer filling the dimensional shortage, and the layer has an internal geometry corresponding to the rated geometry of the stator.

35. A method for manufacturing a pump housing of a rotary piston pump, the method comprising the steps of: - Providing a building surface that is perpendicular to the axis of rotation; - Building a main body infrastructure on the building surface, the main body infrastructure having a prefabricated flange surface and a prefabricated inner wall surface that correspond to the flange surface and the inner wall surface of the pump housing with a reprocessing difference; - Reprocessing the prefabricated flange surface and the prefabricated inner wall surface by removing material with a thickness that compensates for the reprocessing difference; characterized in that the main body infrastructure is manufactured in an additive manufacturing method, in particular in a wire-based or powder-based surfacing method, and the main body infrastructure comprises: -- a wall that defines an internal, preferably gas-filled cavity, the wall having a prefabricated inner wall surface and an outer wall surface, the wall extending in an axial direction with reference to a rotation axis, wherein, --- the prefabricated inner wall surface surrounds the rotation axis and has two partial cylindrical surfaces intersecting each other; - The reprocessing includes a first step in which the additional machining allowance on the prefabricated flange surface is removed by a machining method until the rated size and thus the flange surface is manufactured; and - The reprocessing includes a second step in which the additional machining allowance on the prefabricated inner wall surface is removed by a machining method until the rated size and thus the inner wall surface is manufactured.

36. The method according to any one of claims 29 - 35 above, characterized in that, the wall is constructed as a double wall, the double wall including an inner wall having an inner wall surface and an outer wall having an outer wall surface, and at least one cavity, preferably a gas-filled cavity, is formed between the inner wall and the outer wall.

37. The method according to any one of claims 29 - 36 above, characterized in that, one or more ribs are constructed when constructing the main body infrastructure, the ribs extending through the cavity to reinforce the wall structure surrounding the cavity, preferably each cavity is reinforced by one or more ribs.

38. The method according to any one of claims 20 - 37 above, characterized in that, - the main body infrastructure especially an extrusion body, a stator or a pump housing extends along the manufacturing rotation axis; - The provision of the construction surface includes the provision of a substrate having a surface forming the construction surface; - The construction of the main body infrastructure includes constructing the main body infrastructure on the surface, the surface being horizontally oriented, and constructing the main body infrastructure layer by layer on the surface in a vertically oriented construction direction, the construction direction extending parallel to the manufacturing rotation axis, and the layers of the layer-by-layer constructed main body infrastructure are substantially perpendicular to the manufacturing rotation axis; - Preferably, the substrate forms the end face of the extrusion body, the stator or the pump housing.

39. The method according to any one of claims 20 - 38 above, characterized in that, the additive manufacturing method is a wire-based or powder-based surfacing method, wherein the material application is selectively achieved by melting a metal wire or powder by means of the geometry of the main body infrastructure, especially in such a way that, - continuously melting along a weld bead, the extension direction of the weld bead being controlled by the geometric data of the main body infrastructure; and / or - melting is achieved in an electric arc or a laser beam.

40. The method according to any one of claims 20 - 39 above, characterized in that, in the additive manufacturing method, the material application head moves relative to the construction surface in multiple axes.

41. The method according to any one of claims 20 - 40 above, characterized in that, the construction surface rotates around the manufacturing rotation axis during the construction of the infrastructure.

42. The method according to any one of claims 20 - 41 above, characterized in that, The main body infrastructure is constructed as a wall that defines an internal cavity, preferably filled with gas, the wall having an inner wall surface and an outer wall surface, and the wall having a substantially uniform wall thickness.

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