Lightweight hydraulic design for improved 3D printability

Abstract

The present invention relates to a centrifugal pump with a blade arrangement (8). The blade arrangement (8) comprises a carrier unit (1) in which the blades (2) are arranged. The blade arrangement (8) has a cell unit (5). The cell unit (5) surrounds a cavity (4). The cell unit (5) is formed by a wall (3).

Description

[Technical field]

[0001] The present invention relates to a centrifugal pump having a blade arrangement, the blade arrangement comprising a carrier unit on which the blades are arranged. [Background technology]

[0002] The central component of a centrifugal pump is the impeller, the bladed rotating component of a turbomachine such as a centrifugal pump, where mechanical power is converted into delivery power by the deflection of the flow at the blades.

[0003] Depending on the profile of the streamlines within the impeller, impellers can be classified into various types such as radial impellers, semi-axial impellers, axial impellers, and peripheral impellers.

[0004] To accommodate the blades, all impellers have a carrier disc and, if closed, a cover disc. If an impeller does not have a front or outer cover disc, the impeller is considered to be open.

[0005] Due to their special shape, closed impellers for pumps could essentially only be manufactured by primary forming, especially casting. Primary forming is the main group of manufacturing methods that produce solids with a geometrically defined shape from shapeless substances. Primary forming is used to form the initial shape of the solid and to give the material cohesion.

[0006] Metal and alloy casting is a manufacturing process in which a workpiece is produced from liquid metal. In the die casting process, the melt is filled into a mold and then allowed to solidify therein. The inner surface of the mold is the negative outer surface of the casting.

[0007] DE 10 2015 212 203 A1 describes such an impeller made of a metal casting, in which the blades are arranged in bundles and produced in a special mould into a particularly wear-resistant metal casting.

[0008] This method may result in small defects or small geometric deviations in or on the surface of the material, but it also limits the quality of the surface condition. This may impair the performance of the impeller, which may require finishing operations such as comprehensive balancing and surface treatment. Furthermore, the cast impeller has a large mass, which may make it slower during use in the pump.

[0009] DE 10 2016 205 976 A1 describes a lightweight, non-loosening impeller made of aluminum. Metals such as aluminum, which are preferentially used for lightweight construction, are superior to cast impellers in terms of inertia, but usually do not have the same resistance to wear and corrosion.

[0010] Plastic materials often provide corrosion resistance and at the same time do not become sluggish in terms of operational behavior. DE 10 2014 226 525 A1 describes an impeller made of a lightweight polymer matrix. However, compared to cast materials, plastics are significantly softer and less wear-resistant. Summary of the Invention

[0011] The object of the present invention is to provide a centrifugal pump with a blade configuration which is resistant to wear and corrosion and at the same time does not have a sluggish operating behavior. The blade configuration here is intended to be simple, economical and fast to manufacture. Furthermore, the blade configuration is intended to have an optimal flow profile while being particularly lightweight.

[0012] This object is achieved according to the invention by a centrifugal pump with a blade configuration and a method for its manufacture. Preferred variants are set out in the dependent claims, the description and the drawings.

[0013] According to the invention, the blade configuration comprises cell units surrounding a cavity, the cell units being formed with wear- and corrosion-resistant walls.

[0014] The blade arrangement in the context of the present invention is preferably configured as an impeller or transmission.

[0015] The cell units are elements or segments of cavities surrounded by boundary walls and arranged in a two-dimensional pattern. Advantageously, the cell units are arranged without gaps between them, in this case with a favorable ratio of wall material to volume. The cell units are highly suitable for lightweight designs that are also constructed with stabilization in mind. The cell units or segments are part of a whole, and therefore the entire blade configuration is provided by specifically building an assembly of segments or cell units together.

[0016] A cavity is a mathematical, physical or technical object that has a volume. Any volume enclosed within a structure, for example by a cellular unit, can be a cavity. In this case, the presence of the cavity often changes the underlying structure in terms of strength, mass or elasticity.

[0017] According to the invention, the cell units are arranged directly adjacent to each other, thus forming a blade configuration with high strength and no gaps, which is particularly advantageous since it avoids interrupted walls and / or gaps in the cell units, which are surfaces that are attacked by the abrasive liquid.

[0018] Ideally, cell units that are placed directly adjacent to one another share a wall, which results in a particularly stable blade configuration and at the same time a very lightweight configuration.

[0019] A wall in the context of the present invention refers to a two-dimensional structure that bounds the cavity. By combining a flow-optimized configuration with an optimized wall design, a highly stable blade configuration is achieved that is optimally configured with respect to the flow contour while minimizing mass. The structure of the blade configuration therefore allows maximum savings in the amount of material compared to conventional blade configurations manufactured by casting.

[0020] Preferably, the cell units form a honeycomb structure of a blade configuration. In this case, the honeycomb sections may have a circular, angular and / or trapezoidal configuration. They are arranged directly adjacent to each other and can ideally be configured according to the results of flow and design optimization. The honeycomb structure forms the basis of the blade configuration configured as a lightweight design.

[0021] Advantageously, the walls of the cell units completely enclose the cavities. A blade arrangement configured in this way preferably does not have openly accessible cavities that could adversely affect the fluid flow and the inertial behavior of the blade arrangement. This allows the flow profile of the blade arrangement of the centrifugal pump to be optimally configured.

[0022] In another variant of the invention, not all walls of the cell unit completely surround the cavity. In particular in the case of diffusion devices, preferably diffusers, this is advantageous for the flow guidance and / or formation of the flow-diffusion cell unit, so that the efficiency of the entire centrifugal pump is advantageously influenced.

[0023] Preferably, all walls of the cell unit are integrally formed by the carrier unit and the blade and, optionally, by the cover disk. The integrality is achieved by generative manufacturing, so that the walls surrounding the cavities can be formed particularly quickly and precisely.

[0024] In a further variant of the invention, the walls of the cell unit, the carrier unit and the cover disk are constructed in multiple parts. In such an alternative embodiment, the walls of the cell unit of the blade are generatively applied onto a conventionally manufactured carrier disk. In this way, individually arranged and designed blades can be printed onto a carrier disk manufactured by mass production, taking into account certain customer-specific requirements. Due to the lightweight design of the blades, the inertia of the entire impeller is much smaller than in the case of a completely solid-constructed impeller.

[0025] In one variant of the invention, all the walls of the cell units are formed in multiple parts and / or in a hybrid of carrier units and blades.

[0026] The blade configuration is a lightweight design consisting of cellular units, manufactured according to the invention by generative manufacturing. The term generative manufacturing covers all manufacturing methods in which material is applied layer by layer, thereby producing three-dimensional components, in particular impellers and / or diffusers. In this case, the layer-by-layer construction is carried out from one or more liquid or solid materials, according to predefined dimensions and shapes, under computer control. During the construction, physical or chemical hardening or melting processes occur. Representative materials for "3D printing" include plastics, synthetic resins, ceramics, metals, carbon materials, and graphite materials.

[0027] According to the invention, the blade configuration for the centrifugal pump is produced by generative manufacturing. Selective laser melting and cladding, also called deposition welding, are used in particular to produce the walls of the cell units and the blade configuration. In another variant of the invention, spraying and extrusion of cold gases combined with the application of fusible plastics are also methods that can be used.

[0028] In deposition welding or cladding, the cellular units of the blade configuration are produced by a method in which the basic structure is coated by welding. In deposition welding in this case, the volume is increased by the welding filler metal in the form of wire or powder, which allows the production of particularly complex and flow-optimized shapes of the blade configuration.

[0029] In selective laser melting, powdered metal construction material is applied in a thin layer onto a plate. The powdered material is completely melted locally at each desired location by radiation, forming a solid material layer after solidification. This base plate is then lowered by one layer thickness and powder is applied again. This cycle is repeated until all layers are fused. Excess powder is removed from the finished blade construction.

[0030] For example, the radiation can be a laser beam that creates the blade configuration from individual powder layers. The data to guide the laser beam is created by software on the basis of a 3D CAD body. Instead of selective laser melting, electron beam melting (EBM) can also be used.

[0031] In a particularly advantageous variant of the invention, the fluid-contacting surfaces of the blade configuration are produced from the construction material by successive melting and solidification of layers by radiation. In this case, different properties of the regions of the cell units are produced by a change in radiation. By deliberately controlling the local introduction of heat, a change in the material properties is already carried out during the construction of the blade configuration. This is done by producing different material states of a chemically homogeneous material and thus zones and structures with different properties in the regions of the walls and cell units.

[0032] In one variant of the invention, the blade configuration may be made from different construction materials, preferably including metal powder particles, in particular low-alloy and / or high-alloy steel powder particles, and / or fusible plastics, and / or metal-polymer hybrid materials.

[0033] The construction material for generating the flow profile of the fluid contact surfaces, in particular the blade configuration, is preferably metal powder particles. In one variant of the invention, iron-containing and / or cobalt-containing powder particles are used for this purpose. These may contain additives such as chromium, molybdenum, nickel, etc. The blade configuration is therefore configured to be particularly wear- and corrosion-resistant.

[0034] According to the invention, the cell units of the blade configuration are formed by additive manufacturing. The 3D geometry of the walls and the cell units are stored in the software as a data set. Various additive method tools can work where the walls are to be formed and can be additively built up layer by layer. Advantageously, the appropriate construction process for each construction material can be carried out successively or simultaneously for each layer, so that a complex blade configuration made of different materials is formed, whose cell units are optimally and individually adapted to the requirements of the subsequent use.

[0035] In one variant of the invention, the honeycomb structure is produced by a fused layer tool of additive manufacturing, which applies an array of dots from a fusible plastic onto a surface. By extrusion through a nozzle and subsequent solidification by cooling at the desired location, a load-bearing structure is produced, in particular in the form of a cell unit and / or in the form of a honeycomb structure. In particular, the support area of ​​the blade arrangement is produced so as to form a cavity with the load-bearing structure, so that the blade arrangement has a very high strength with a very low mass. The construction of the blade arrangement is conventionally carried out by repeatedly scanning the working surface row by row and then displacing the working surface upwards to form a stack, so that the support area of ​​the blade arrangement is formed.

[0036] According to the invention, the walls have a thickness of less than 3 mm, preferably less than 2 mm, in particular less than 1 mm. Advantageously, the walls are constructed to be particularly thin, so that the effect of the lightweight design is further enhanced.

[0037] In order to achieve a particularly stable blade configuration with the lowest possible mass, reinforcing ribs are arranged inside the cell units and / or between adjacent cell units. Ideally, the walls are constructed particularly thin and the blade configuration is constructed as light as possible, with stability optimally generated by precisely positioned reinforcing ribs.

[0038] Preferably, the cell units, in particular the carrier discs and the cover discs, are radially and / or circumferentially aligned. This type of arrangement and alignment helps to reduce the number of walls, so that the impeller or diffuser can be constructed to be particularly lightweight.

[0039] According to the invention, the outer walls of the cell units form the fluid contact surfaces of the blade configuration. These are optimally adapted to the requirements for use in CFD simulations and can be generated not only individually but also quickly by generative manufacturing.

[0040] Advantageously, the walls and / or the reinforcing ribs are manufactured from a metallic material, which may contain alloying components, in order to form a particularly wear- and corrosion-resistant, lightweight blade construction. Alternatively, plastic or ceramic materials may be used.

[0041] In one variant of the invention, the walls and / or the reinforcing ribs are manufactured from a combination of materials and are therefore formed as a hybrid material. In another variant of the invention, the cavities of the cell units are filled with a filler. Preferably, the filler is configured as a lightweight plastic so that the stability of the blade configuration is increased and at the same time the mass of the blade configuration is kept low.

[0042] According to the invention, the blade arrangement configured as an impeller can comprise a cover disk formed of cell units, which are configured with walls surrounding cavities, so that advantageously the entire impeller is configured as a lightweight design, which makes the impeller very stable with a very low mass.

[0043] Ideally, the lightweight design of the blade configuration would result in very short so-called printing times for additive manufacturing, making generative manufacturing of the blade configuration significantly more competitive compared to production by casting, especially with regard to economic interests.

[0044] Furthermore, the individual configuration of the blade geometry, flow contour and arrangement of the reinforcing ribs is particularly advantageous. In contrast to cast impellers, no finishing or system-specific adjustments to the blade configuration are necessary to accommodate customer-specific requirements. The blade configuration can be designed in a way that is optimized for the intended use and can be manufactured individually without incurring costs for individual moulds with elaborate finishing.

[0045] According to the present invention, inventory of multiple impellers or diffusers can preferably be avoided. Existing design data of the impeller or diffuser can be used for direct generative remanufacturing if required, thus avoiding the overhead costs of inventory.

[0046] Ideally, the lightweight design of the blade configuration made up of cell units allows target prototypes to be built very quickly and tested in a test system, thus offering the advantage that the development time for new impellers or diffusers can be reduced.

[0047] According to the invention, the lightweight design of the blade configuration can be used in applications where the lightweight and non-slack blade configuration opens up completely new possibilities of use. The blade configuration according to the invention is preferably suitable for use in flow pumps for microdosing applications.

[0048] Further features and advantages of the invention will become apparent from the description of exemplary embodiments with the aid of the drawings, and from the drawings themselves. [Brief description of the drawings]

[0049] [Figure 1]1 shows a central cross section of a blade configuration according to the present invention. [Diagram 2] A cross-sectional view of the blade is shown. [Diagram 3] 1 shows the cross-sectional area of ​​a carrier unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] 1 shows a central cross-sectional view of a blade arrangement 8 according to the invention, which in this exemplary embodiment is configured as an impeller. The carrier unit 1 and the cover disk 7 have a cell unit 5 surrounding a cavity 4. The cell unit 5 is formed by a wall 3, on some of which reinforcing ribs 6 are arranged.

[0051] In this exemplary embodiment, the wall 3 is synthetically manufactured from corrosion-resistant alloy particles that are transformed by the energy input by radiation. The surface of the impeller is therefore configured to be particularly wear-resistant. The impeller is entirely composed of cell units 5 in the form of cavity segments. The impeller is therefore particularly light and not sluggish in terms of its operating behavior.

[0052] FIG. 2 shows a cross section of a blade 2 of a blade arrangement 8, which in this exemplary embodiment is configured as an impeller. The blade 2 has a cell unit 5 surrounding a cavity 4. The cell unit 5 is formed by a wall 3. At particularly stressed points of the impeller, reinforcing ribs 6 are arranged on the wall 3. In this exemplary embodiment, the wall 3 of the blade 2 is configured in a particularly flow-optimized manner and has a thickness of less than 3 mm, preferably less than 2 mm, in particular less than 1 mm. The impeller with the blade 2 is therefore configured to be particularly lightweight. In this case, adjacent cell units 5 share a wall 3, so that the wall 3 of the blade 2 and the carrier unit 1 are configured as a whole in one piece.

[0053] Figure 3 represents a cross section of a carrier unit 1 of a blade configuration 8. The carrier unit 1 has cell units 5 surrounding a cavity 4. The cell units 5 are formed from walls 3, some of which have reinforcing ribs 6 arranged on them. In this case, the cell units 5 are aligned radially and circumferentially.

Claims

1. A centrifugal pump having a blade configuration (8), said blade configuration (8) having a carrier unit (1) in which blades (2) are arranged, said blade configuration (8) having a plurality of cell units (5) surrounding a cavity (4), said cell units (5) being formed by walls (3), a centrifugal pump characterized thereby.

2. The centrifugal pump according to claim 1, characterized in that the cell units (5) are arranged directly adjacent to each other.

3. The centrifugal pump according to claim 1 or 2, characterized in that the cell units (5) arranged directly adjacent to each other share a wall (3).

4. The centrifugal pump according to claim 1 or 2, characterized in that the cell units (5) form a honeycomb structure.

5. The centrifugal pump according to claim 1 or 2, characterized in that the walls (3) of the cell units (5) completely surround the cavity (4).

6. The centrifugal pump according to claim 1 or 2, characterized in that the walls (3) of the cell units (5) have an open cavity (4).

7. The centrifugal pump according to claim 1 or 2, characterized in that all walls (3) of the cell units (5) are integrally formed by the carrier unit (1) and the blades (2).

8. The centrifugal pump according to claim 1 or 2, characterized in that all walls (3) of the cell units (5) are formed in a plurality of parts and / or by a hybrid of the carrier unit (1) and the blades (2).

9. The centrifugal pump according to claim 1 or 2, characterized in that the thickness of the wall (3) is less than 3 mm.

10. The centrifugal pump according to claim 1 or 2, characterized in that reinforcing ribs (6) are arranged inside the cell units (5) and / or between adjacent cell units (5).

11. The centrifugal pump according to claim 1 or 2, characterized in that the cell units (5) are aligned in the radial direction and / or circumferential direction.

12. The centrifugal pump according to claim 1 or 2, characterized in that the walls (3) of the cell units (5) form the fluid contact surface of the blade configuration (8).

13. The centrifugal pump according to claim 1 or 2, characterized in that the wall (3) and / or the reinforcing rib (6) is manufactured from a metallic material.

14. The centrifugal pump according to claim 1 or 2, characterized in that the wall (3) and / or the reinforcing rib (6) is manufactured from a combination of materials.

15. The centrifugal pump according to claim 1 or 2, characterized in that the cavity (4) of the cell unit (5) is at least partially filled with a material.

16. The centrifugal pump according to claim 1 or 2, characterized in that the blade configuration (8) comprises a cover disk (7), and the cover disk (7) has a cell unit (5) having a cavity (4) surrounded by a wall (3).

17. A method for manufacturing a centrifugal pump having a blade configuration (8) according to claim 1 or 2 by means of an integrated manufacturing unit, comprising: forming a cell unit (5) from a constituent material; selectively applying energy in the form of radiation, temperature and pressure to form the wall (3) and / or the reinforcing rib (6); intentionally varying the application of the energy to produce a wall (3) and a reinforcing rib (6) having defined properties; intentionally varying the thickness of the wall (3) to adapt to load requirements and having the method.

18. Use of a centrifugal pump having a blade configuration (8) according to claim 1 or 2 as a microdosing pump.

Images