MANUFACTURING AN IRON IN A HYBRID PROCESS

Description

[0001] The invention relates to an impeller for a centrifugal pump with a support disc on which blades are arranged.

[0002] An impeller is a rotating component of a turbomachine, such as a centrifugal pump, equipped with blades. Here, mechanical power is converted into pumping power by deflecting the flow at the blades.

[0003] To accommodate the blades, all impellers have a rear support disc and, in the case of closed impellers, also a front cover disc. Alternatively, an impeller can be considered to have an inner cover disc and, in the case of closed impellers, also an outer cover disc. If an impeller lacks either the front or outer cover disc, it is considered open.

[0004] German patent application DE 10 2016 225 018 A1 describes an exemplary radial impeller for a centrifugal pump. Blades are arranged between a support disc and a cover disc. The fluid flows axially towards the impeller, is deflected by 90°, and then exits the impeller radially.

[0005] In additive manufacturing of components, the respective product is built up layer by layer from a build material applied to a substrate. The build material is usually in powder form. The powder is locally melted completely at the respective points using radiation and, after solidification, forms a solid layer. The base plate, on which the powder is located, is then lowered by the thickness of one layer, and more powder is applied. This cycle is repeated until all layers of the component have been produced. The finished component is then cleaned of excess powder.

[0006] The data for guiding the radiation is generated using software based on a 3D CAD model. A laser beam, for example, can be used as the radiation source. Alternatively, an electron beam (EBM) can be used instead of selective laser melting.

[0007] For each layer, the areas that form the component's structure are selectively melted. In the next step, to bond the layer below to the layer above, the radiation melts up to three underlying layers, which then fuse with the top layer during the rapid cooling process.

[0008] German patent DE 10 2015 202 417 A1 describes a flow-guiding component, in particular a radial impeller, which is produced by successive solidification of layers using radiation. By varying the radiation, functional areas with different properties are created.

[0009] US 2017 / 260997 A1 describes a method for manufacturing an impeller from a plurality of tubular components, wherein each tubular component forms a corresponding flow channel of the impeller and has an inlet and an outlet.

[0010] US 2019 / 313878 A1 discloses a wash pump impeller with a plurality of blades formed integrally with the hub, wherein the blades extend from the hub at an extension angle relative to the flow surface of the hub, the extension angle being less than 60 degrees.

[0011] Components such as impellers manufactured using additive manufacturing are very limited in their dimensions. Currently, only components up to about thirty centimeters in size can be produced. Furthermore, additive manufacturing is expensive compared to conventional methods for components intended for large-scale production.

[0012] The object of the invention is to produce an impeller, even a large one, for flow-carrying components. The impeller should be assembled from segments produced by different manufacturing processes. The segments should be individually customizable with regard to material combinations, properties, and material thickness. This impeller should be simple and cost-effective to manufacture.

[0013] This problem is solved according to the invention by an impeller for a centrifugal pump and a method for manufacturing an impeller. Preferred embodiments can be found in the dependent claims, the description, and the drawings.

[0014] According to the invention, an impeller for a centrifugal pump with a support disc on which blades are arranged is constructed as a hybrid component consisting of at least one additive component and at least one conventional component, wherein at least one component is divided into at least two segments.

[0015] An additively manufactured component is produced using an additive manufacturing process. The term additive manufacturing encompasses all manufacturing processes in which material is applied layer by layer to create three-dimensional components. This layer-by-layer construction is computer-controlled and uses one or more liquid or solid materials according to predefined dimensions and shapes. Physical or chemical hardening or melting processes occur during the build-up. Typical materials for 3D printing include plastics, resins, ceramics, metals, carbon, and graphite materials.

[0016] The term "conventional component" refers to a component produced by primary forming, forming, or a subtractive manufacturing process. Primary forming is a major group of manufacturing processes in which a solid body with a geometrically defined shape is produced from a formless material. Primary forming is used to create the initial shape of a solid body and to establish material cohesion. In forming, blanks made of plastically deformable materials are deliberately shaped without removing any material from the blanks. In subtractive manufacturing, material is removed from the workpiece. Besides the resulting component, this process primarily produces chips.

[0017] According to the invention, the blades are produced from a powdered metal material using an additive manufacturing process, preferably by selective laser melting with a laser or electron beam. In an alternative embodiment of the invention, the blades can also be produced from meltable plastic by extrusion and hardening. The invention also provides for the production of hybrid blades in which thin metal layers are applied to a plastic framework by means of cold gas spraying.

[0018] Advantageously, the impeller has a cover plate. An impeller with a cover plate is called a closed impeller of a centrifugal pump, which, through its interaction with a gap ring, exhibits excellent efficiency with extremely low backflow.

[0019] The support disc is manufactured as a conventional and / or additively manufactured component. Preferably, the support disc is a cast product. In an alternative embodiment of the invention, the support disc is preferably formed in segments by selective laser melting, which are then joined together with the blades in an integrated manufacturing unit using a joining process to form a support disc with blades.

[0020] According to the invention, the cover plate is designed as a conventional component, preferably manufactured by a casting process. Alternatively, the cover plate, and in particular its segments, can be manufactured by a machining process, preferably by milling. Ideally, the cover plate is divided into at least two segments. A component such as the cover plate and / or the support plate has more than two, preferably more than three, and in particular more than four, and / or fewer than ten, preferably fewer than nine, and in particular fewer than eight, segments.

[0021] According to the invention, the number of segments corresponds to the number of blades. Both the segments and the blades have a radially outwardly curved shape. In this respect, the segments are designed as a section between two blades. According to the invention, a connecting joint serves as a joining element connecting two segments and a blade. This results in an impeller for a centrifugal pump in which the number of blades corresponds to the number of connecting joints. The connecting joints are preferably produced using a joining process, in particular welding, in an integrated manufacturing unit.

[0022] The production of even large impellers using an integrated, additive manufacturing process is particularly advantageous. By employing a highly maneuverable robot arm equipped with various additive manufacturing and joining tools, even very complex and large impellers can be manufactured. For example, the blades can be created using selective laser melting, the conventional components can be positioned with the blades using a clamping tool, and the joints can be formed with a welding tool.

[0023] Joining involves permanently connecting two or more solid bodies, the joining parts, with geometrically defined shapes. Welding creates an inseparable bond between segments and a blade using heat and / or pressure, with or without filler materials. The filler materials are typically supplied in the form of rods or wires, melted, and solidify in the joint between the joining partners to create the connection. Welding is a metallurgical joining method that produces high-strength joints.

[0024] In an alternative version of the invention, pressing could be used as the joining method. In this process, large forces create a permanent bond between the segments and the blade.

[0025] Advantageously, the joint connects the segments of a component and the blades almost without a gap. The gap is less than 10 µm, preferably less than 7.5 µm, and particularly less than 5 µm. Ideally, this results in an impeller made of many individual parts that exhibits no fluid dynamic disadvantages compared to an impeller produced by primary forming. A particularly significant advantage is the production of impeller geometries that are difficult or impossible to create using conventional manufacturing methods. This allows even large impellers with improved hydraulic efficiencies to be manufactured as hybrid components.

[0026] According to the invention, the blades have contact points for the segments, which is what makes gap-free joining possible. A firm and secure contact is an important prerequisite for the joining process used to create the connection joint between the segments and the blade.

[0027] According to the invention, the joining surfaces of the segments and the blade are rounded and / or chamfered to form the joint. The arrangement prior to joining is virtually gap-free and securely positioned to prevent slippage within the integrated manufacturing unit.

[0028] In an alternative version of the invention, a stop and / or a support groove can be formed on the shovel to position the segments for the joining process.

[0029] According to the invention, the method for manufacturing an impeller using an integrated manufacturing unit consists of forming the segments of a cover plate and / or the segments of a support plate by primary forming and / or machining, forming the blades by an additive manufacturing process, and joining the blades and the segments to form a hybrid impeller.

[0030] The inventive method is characterized by particularly customizable segments and / or blades. Adjustments to the impeller can be made according to the requirements of the centrifugal pump through additive manufacturing. The comparatively inexpensive, segmented, conventionally manufactured components and the joining process significantly reduce the cost of expensive individual production. Furthermore, the additively manufactured components can have a shape that achieves a higher pump efficiency, a result that was previously unattainable using conventional manufacturing methods.

[0031] Ideally, the impeller, which is produced as a hybrid component from at least one additively manufactured component and at least one conventionally manufactured component, is used as the impeller for a centrifugal pump. This impeller is characterized by excellent fluid-mechanical properties and can have a size that cannot be produced with known additive manufacturing units.

[0032] Further features and advantages of the invention will become apparent from the description of exemplary embodiments with reference to the drawings and from the drawings themselves.

[0033] This shows: Fig. 1 a top view of an impeller, Fig. 2 a top view of an impeller without a cover plate, Fig. 3 a perspective view of two segments and a blade.

[0034] Fig. 1 Figure 1 shows a top view of a closed, radial impeller 1. The cover plate 2 is assembled from segments 5 with connecting joints 4. Preferably, the connecting joint 4 is a weld. The blades 3 are arranged between the cover plate 2 and the support plate 6.

[0035] The shape of a segment 5 is formed as a section between two blades 3. The connecting joints 4, the side edges of the segments 5 and the blades 3 have an outwardly curved shape.

[0036] Fig. 2 Figure 1 shows a top view of an impeller 1 without a cover plate. The blades 3 are arranged on the support plate 6. The blades 3 have an outwardly curved shape.

[0037] Fig. 3Figure 1 shows a perspective view of two segments 5 and a blade 3. The segments 5 and the blade 3 are joined by a joint 4. In this embodiment, the joint 4 is designed as a weld, preferably formed by an integrated manufacturing unit. The joint 4 connects the segments 5 and the blade 3 almost without a gap. The gap 7 is less than 10 µm, preferably less than 7.5 µm, and particularly less than 5 µm. In this embodiment, the joining surfaces 8 of the segments 5 and the blade 3 for forming the joint 4 are rounded, so that the bearing surface for the joining process is optimally designed. In another embodiment, angled or angular joining surfaces are also conceivable.

Claims

1. Impeller (1) for a centrifugal pump, with a rear shroud (6) on which blades (3) are arranged, characterized in that the impeller (1) has been constructed as a hybrid component from at least one generative component and at least one conventional component, wherein at least one component has been subdivided into at least two segments (5), wherein the number of segments (5) corresponds to the number of blades (3), wherein both the segments (5) and the blades (3) exhibit a shape that is curved radially outwards, wherein the shape of a segment (5) takes the form of a constituent part between two blades (3), wherein a connecting joint (4) takes the form of a connecting element between two segments (5) and a blade (3), wherein the blades (3) exhibit points of support for the segments (5) and the joining surfaces (8) of the segments (5) and of the blades (3) have been rounded and / or bevelled for the purpose of forming the connecting joint (4).

2. Impeller (1) according to Claim 1, characterized in that the blades (3) have been constructed generatively.

3. Impeller (1) according to Claim 1 or 2, characterized in that the impeller exhibits a front shroud (2).

4. Impeller (1) according to Claim 3, characterized in that the front shroud (2) takes the form of a conventional component.

5. Impeller (1) according to one of Claims 1 to 4, characterized in that the rear shroud (6) has been formed conventionally and / or generatively.

6. Impeller (1) according to one of Claims 1 to 5, characterized in that a component exhibits more than two segments (5), preferably more than three, in particular more than four, and / or fewer than ten, preferably fewer than nine, in particular fewer than eight.

7. Impeller (1) according to one of Claims 1 to 6, characterized in that the connecting joint (4) connects the segments (5) and the blade (3) in an almost gap-free manner.

8. Impeller (1) according to Claim 7, characterized in that the gap (7) amounts to less than 10 µm, preferably less than 7.5 µm, in particular less than 5 µm.

9. Method for producing an impeller (1) according to Claims 1 to 8 by means of an integrative manufacturing unit, with the following steps: • forming the segments (5) of a front shroud (2) and / or of a rear shroud (6) by primary shaping and / or machining, • forming the blades (3) by a generative method, • joining the blades (3) and the segments (5) to form a hybrid impeller.

10. Use of a hybrid component according to Claims 1 to 8 for a centrifugal pump.