Fluid machine impeller and impeller manufacturing method

Abstract

The invention relates to a method (100) for producing a turbomachine impeller (10), comprising a main body (11) and at least one blade (12), the main body (11) and the blade (12) being integrally bonded, and wherein, preferably in the following sequence, at least the following steps are carried out: a) machining (101) a blank (1) made of solid material in order to produce a first section (11.1) of the main body (11); b) applying (102) at least one material layer (13) to the first section (11.1) of the body (11) by means of an additive manufacturing method in order to at least partially produce a second section (11.2) of the body (11); c) applying (103) at least one material layer (13) to the first section (11.1) and / or the second section (11.2) by means of an additive manufacturing method in order to at least partially produce at least one blade (12) on the body (11).

Description

Technical Field

[0001] The invention relates to a method having the features of independent claim 1 , an impeller having the features of independent claim 17 , and a turbomachine having the features of independent claim 18 . Background Art

[0002] The impellers of fluid machinery are subject to high mechanical loads during operation, and in order to obtain the highest possible efficiency and achieve the desired operating characteristics, they have partially complex geometries. In particular, the surface geometry that interacts with the flow during operation may be at least partially the result of fluid technology optimization and have a complex structure. This may involve, for example, the contour design of the blades or impeller hub (i.e., the impeller body) placed on the impeller. In the processing technology based on which the impeller is manufactured, some of these geometries optimized by fluid technology can only be manufactured accurately enough with a large investment, which leads to correspondingly high processing costs. At the same time, it is also necessary to always ensure that the connection between the blades and the body has the highest possible load-bearing capacity in order to minimize mechanical failure of the impeller during operation. The cause of mechanical failure may be, for example, the centrifugal force of the blades caused by high rotational speed, or the influence of foreign matter entering the impeller.

[0003] One way to manufacture fluid machinery impellers is to machine solid material blanks, where the entire impeller is manufactured from the blank. Therefore, since the solid material blank must completely cover the final dimensions of the impeller, the amount of material that needs to be removed during the machining process is correspondingly large. The time required to remove the material and the large amount of excess material make it difficult to achieve efficient and economical machining. Summary of the invention

[0004] The object of the present invention is therefore to at least partially overcome at least one of the above disadvantages. In particular, the object of the present invention is to provide a method for producing an impeller for a turbomachine which allows efficient and / or cost-effective and / or material-saving processing of impellers, preferably with complex geometries.

[0005] The above tasks are accomplished by a method having the features of independent claim 1, an impeller having the features of independent claim 17, and a fluid machine having the features of independent claim 18. Other features and details of the present invention can be found in the dependent claims, the specification, and the drawings. Here, the features and details described with respect to the method of the present invention are obviously also applicable to the impeller of the present invention and / or the fluid machine of the present invention, and vice versa, so the disclosures of the various aspects of the invention can generally or can be referred to each other.

[0006] The present invention provides a method for producing an impeller for a fluid machine or an impeller to be used in a fluid machine, the impeller comprising a body and at least one blade, wherein the body and the at least one blade (the blade) are connected by material bonding, and wherein at least the following steps are preferably performed in the following order:

[0007] a) machining a blank consisting of solid material to produce a first section of the body,

[0008] b) applying at least one material layer to the first section of the body using an additive manufacturing method to at least partially generate the second section of the body,

[0009] c) applying at least one material layer to the first section and / or the second section using an additive manufacturing method to at least partially generate at least one blade on the body.

[0010] In other words, it is provided that in one processing step, preferably the first processing step, a section of the impeller body is first produced from a solid material blank. In this case, the geometrical dimensions of the first section are smaller in at least one dimension than the blank or the complete and / or finished body produced in a subsequent method step. In particular, the blank can be smaller than the complete and / or finished body produced in a subsequent method step, at least in terms of radial extension. Thus, the solid material blank used in the processing step can be selected to be smaller than that of other production methods, thereby reducing excess material in the impeller processing.

[0011] In another processing step, preferably the second processing step, at least one material layer is applied to the first section of the body to at least partially, preferably completely generate the second section of the body. This is achieved by using an additive manufacturing method, preferably for layering and / or accurately forming the desired geometry or the geometry of the second section. As a result, the second section of the body can be manufactured or generated in a particularly material-saving manner. At the same time, the use of additive manufacturing allows the formation of almost any complex geometry in a relatively simple manner. Costly operations of workpiece cutting, such as complex multi-dimensional motion processes when milling the impeller shape from a solid material blank, can be effectively avoided or reduced by using additive manufacturing. Therefore, the time and cost expenditure required for manufacturing the impeller can be reduced. A reliable, preferably material-joined connection between the first and second sections can also be achieved by using additive manufacturing, which can withstand the high mechanical loads during the operation of the impeller. In particular, the step can include preferably applying a plurality of (especially a large number of) material layers in sequence. It is preferably conceivable that the second section includes at least 100, preferably at least 200, and particularly preferably at least 500 material layers.

[0012] In a further processing step, preferably the third processing step, at least one material layer is applied to the first section of the body and / or the second section of the body in order to at least partially, in particular completely generate at least one blade, in particular all blades, on the body. This is achieved by using an additive manufacturing method, preferably for layering and / or precisely forming the desired geometry or the geometry of at least one blade. As a result, at least one blade, preferably all blades, of the impeller can be manufactured in a particularly material-saving manner. At the same time, the use of additive manufacturing methods allows the formation of almost any complex geometry, which has proven to be advantageous in particular in the design of highly optimized 3D blade profiles. Costly operations of workpiece cutting, such as complex multi-dimensional motion processes when milling the impeller shape from a solid material blank, can be effectively avoided or reduced. The time and cost expenditure required for manufacturing the impeller can therefore be reduced. A reliable, preferably material-joined connection between at least one impeller blade and the impeller body or the first and / or second section can also be achieved by using additive manufacturing methods, which can withstand the high mechanical loads during the operation of the impeller. In particular, this step can include preferably applying a plurality of, in particular a large number of, material layers in sequence. It can be provided that at least one blade comprises 50, preferably at least 100, particularly preferably at least 200 material layers. It can also be provided that at least one material layer deposited in this step, in particular all material layers, simultaneously covers the first section and the second section.

[0013] “Applying at least one material layer to the first and / or second section of the body” includes the concept of directly depositing only the first material layer onto the first and / or second section, and depositing at least one subsequent material layer (preferably subsequently) onto the corresponding material layer deposited previously, thereby only indirectly depositing it onto the first and / or second section of the body. It also includes the concept of first depositing multiple material layers (for example in parallel) directly onto the first and / or second section, and only then depositing at least one subsequent layer onto at least one previously deposited material layer, thereby only indirectly depositing it onto the first and / or second section. In other words, each (especially continuous) layered construction during the additive manufacturing process is included in the concept of the present invention, especially at least with respect to generating the second section of the body and / or at least one blade, i.e. steps b) and / or c).

[0014] It can be provided within the scope of the invention that the fluid machine is a fluid machine (compressor) for compressing a fluid flow, preferably continuously operating. The fluid machine can also be a fluid machine (turbine) for at least partially expanding a fluid flow. The fluid guided in the fluid machine can preferably be a compressible fluid, or the fluid machine can be designed to guide a compressible fluid. The fluid can be, in particular, a gas and / or a vapor.

[0015] The fluid machine can have a plurality of stages, which are preferably flowed through or can be flowed through by the fluid flow in sequence. It can be provided that each stage comprises at least one impeller and / or guide wheel. In addition, the fluid machine can include at least one shaft, wherein at least one impeller, preferably all impellers, are connected to the shaft so that the shaft and the impeller can rotate together. It can also be provided that the fluid machine has a plurality of shafts, and each shaft is connected to at least one impeller.

[0016] When the fluid machine is designed as a compressor, the impeller is at least used to transfer kinetic energy from the shaft to the fluid flow guided in the fluid machine. To this end, the impeller is driven to rotate by a shaft connected to the impeller. The energy input into the fluid by the rotation of the impeller and in particular by the blade system or blades of the impeller can be at least partially converted into pressure energy in at least one impeller and / or at least one guide wheel through directional flow guidance and deceleration, so that the fluid flow flowing through the fluid machine is pressurized or compressed.

[0017] When the fluid machine is designed as a turbine, the impeller is used at least to extract kinetic energy and / or pressure energy from the fluid flow flowing through the fluid machine and transfer it to a shaft connected to the impeller, that is, thereby rotating the shaft. To this end, the fluid flow flowing through the fluid machine is at least partially expanded in at least one impeller and / or at least one guide wheel of the fluid machine. Thereby, the fluid flow is accelerated and directed to the impeller or, in particular, the impeller blades, so that a torque can be generated on the shaft and thus the shaft is rotated.

[0018] The guide wheel of a fluid machine is a static component, which is used at least to deflect the fluid flow flowing through the fluid machine so that the fluid flows as best as possible to the blades of the next impeller in the direction of the fluid flow. The blade system or the guide vane of the impeller itself can also be designed for at least partial expansion or acceleration (turbine) and / or compression or deceleration (compressor) of the flow.

[0019] Blades are blades arranged on the impeller body, which are used at least to guide the flow in the impeller and / or achieve the desired flow deflection. Depending on the working mode of the fluid machine (compressor or turbine), the blade channel formed by two blades can be used to at least partially slow down and / or compress the fluid flow (compressor) or at least partially expand and / or accelerate the fluid flow.

[0020] It can be provided within the scope of the invention that the impeller is a radially configured impeller, in particular a centrifugal compressor impeller or a centrifugal turbine impeller, and / or that the impeller is designed in such a way that the fluid flow flows into the impeller axially or essentially axially and / or the fluid flow flows out of the impeller radially or essentially radially. Preferably, any circumferential component of the velocity is not taken into account in the description. The advantages of the method according to the invention are particularly evident when machining radially configured impellers. In principle, however, the concept of the invention also includes other impeller configurations, for example axially configured impellers (axial compressor impellers or axial turbine impellers). This also applies to mixed forms of the configurations described, in particular to impellers of diagonal flow compressors.

[0021] It should be understood here that the axial direction refers to the direction along the impeller rotation axis or parallel to the impeller rotation axis, and the radial direction refers to the direction orthogonal to the impeller rotation axis.

[0022] It can be provided that the main body is completely composed of the first section and the second section, or the first section and the second section completely form the main body. In other words, it can be provided that the main body does not include other sections except the first section and the second section.

[0023] It can be provided within the scope of the invention that the body is designed for at least partial connection to a shaft. The body can be designed at least partially, in particular completely or substantially completely, in rotational symmetry. It can also be provided that the body is designed or serves as a support for at least one, in particular all, blades. In other words, it can be provided that the body is designed without blades or does not comprise leaves, in particular blades. It can also be provided that at least one blade of the impeller at least partially spans the first and second sections.

[0024] It is conceivable within the scope of the invention that the first section and the second section are at least partially connected by material bonding. It can also be provided within the scope of the invention that at least one blade is at least partially connected by material bonding to the main body, in particular the first section and / or the second section. By means of the material bonding connection, a particularly simple and at the same time load-bearing connection is formed between the first and second section or the main body and the at least one blade.

[0025] It can be provided within the scope of the invention that at least two steps of the method according to the invention are carried out at least partially simultaneously, or that their implementation at least partially overlaps in time. In particular, this may involve at least steps b) and c). It is therefore conceivable that at least one material layer is applied to the first section of the body to generate the second section of the body while at least one material layer has already been applied to at least the first section of the body to generate at least one blade. This can speed up the manufacturing method. It is also conceivable that at least one step, preferably at least steps b) and / or c), is repeatedly implemented during the impeller manufacturing process.

[0026] It may be advantageous within the scope of the invention that the application of the material layer in step b) and / or step c) is carried out by build-up welding, preferably laser build-up welding, in particular when using additives. In laser build-up welding, the workpiece surface, in particular the main body surface, is locally melted by laser and the additive material is simultaneously applied to the molten surface. Under the action of the laser or in the immediate vicinity of the molten workpiece surface, the additive material also melts and is connected to the workpiece in a material-joining manner. By supplying the additive material, local material growth on the workpiece can be achieved, so that the desired geometry can be formed onto an existing workpiece, here the main body, preferably in layers, in particular by repeatedly performing the process. In other words, by arranging a plurality of weld beads or weld beads at least partially side by side and / or one above the other or overlappingly on the workpiece surface, in particular the surface of the first and / or second section of the main body, a 3D shape can be preferably formed in layers on the workpiece surface.

[0027] The additive material can be supplied in the case of laser build-up welding, preferably in powder form or as a solid, for example in the form of a rod or wire. The material constituting the additive material can be the same as the material of the workpiece to be built-up with the additive material. In particular, the additive material can consist of the same material as the first and / or second section of the body. The build-up welding can be carried out at least partially continuously, in particular along a previously determined contour or a previously determined path of the workpiece surface or the first and / or second section surface. By using additive manufacturing methods, in particular build-up welding, to preferably form the geometry in layers, the desired body geometry can be reliably generated with only a small amount or no excess material.

[0028] It can be provided within the scope of the invention that the rotation axis of the first section and the rotation axis of the second section are arranged coaxially. In other words, it can be provided that the first section and the second section are at least partially rotationally symmetrical and the respective rotation axes of the first and second sections are arranged coaxially.

[0029] It can also be provided within the scope of the invention that the second section at least partially, in particular completely surrounds the first section. In other words, it can be provided that at least in step b) the material layer applied to the first section at least partially extends over the periphery or the periphery of the first section and thus at least partially surrounds the first section.

[0030] It is conceivable that the first section extends at least between a first inner radius and a first outer radius, and the second section extends at least between a second inner radius and a second outer radius, wherein preferably the first outer radius is equal to the second inner radius. Additionally or alternatively, it can be provided that the second section is generated on an axially or substantially axially extending outer surface of the first section.

[0031] It is conceivable within the scope of the invention that the first section and the second section of the body are at least partially made of the same material or are made in a materially uniform manner, and / or that at least one section of the body, in particular the first and / or the second section, and at least one blade are at least partially made of the same material or are made in a materially uniform manner. This results in a particularly high load-bearing capacity and / or durability of the impeller. In addition, in particular by manufacturing using an additive manufacturing method, in particular cladding, a very reliable connection can be formed between the first and second section and / or the at least one blade and the first and / or the second section.

[0032] It can be provided within the scope of the invention that at least one section of the body, in particular the first and / or the second section and / or at least one blade is at least partially manufactured or formed from martensitic steel and / or precipitation hardened steel. In particular, it can be provided that the impeller is manufactured or formed completely from martensitic steel and / or precipitation hardened steel. This results in the advantage of low-cost production of the impeller with a high mechanical load-bearing capacity. Furthermore, the use of such materials in additive manufacturing methods, in particular welding, has proven to have significant advantages in terms of their processing properties.

[0033] According to the invention, it is conceivable that the steel contains at least one of the following alloying elements in an amount of:

[0034] 10 to 20%, preferably 13 to 18%, particularly preferably 15 to 17%, of chromium,

[0035] 1% to 7%, preferably 2% to 6%, particularly preferably 3% to 5% nickel,

[0036] 1% to 7%, preferably 2% to 6%, particularly preferably 3% to 5% copper.

[0037] The above percentages refer to the mass content (mass fraction) of each alloying element in the steel. Steel containing at least one of the above alloying elements and the content within the specified range has significant advantages in terms of processing performance within the scope of the present invention and the load-bearing capacity and durability of the impeller manufactured therefrom. It has been proven that excellent results can be obtained in steel alloys containing all of the above alloying elements and the content within the specified range, especially containing 15% to 17% chromium, 3% to 5% nickel and 3% to 5% copper.

[0038] It is also conceivable that the steel has at least one of the following material property parameters:

[0039] 900N / mm 2 Up to 1400N / mm 2 , preferably 1000N / mm 2 Up to 1300N / mm 2 , particularly preferably 1070N / mm 2Up to 1270N / mm 2 The tensile strength (R m ),

[0040] At least 800N / mm 2 , preferably at least 900 N / mm 2 , particularly preferably at least 1000 N / mm 2 Yield strength (R p0.2 ),

[0041] 100kN / mm 2 Up to 300kN / mm 2 , preferably 150kN / mm 2 Up to 250kN / mm 2 , particularly preferably 180 kN / mm 2 Up to 220kN / mm 2 , especially 200kN / mm 2 The elastic modulus,

[0042] an elongation at break (A5) of at least 5%, preferably at least 8%, particularly preferably at least 10%,

[0043] A hardness (HB30) of 250 HB to 450 HB, preferably 300 HB to 400 HB, particularly preferably 330 HB to 390 HB,

[0044] A notched impact toughness of at least 10 J, preferably at least 15 J, particularly preferably at least 20 J.

[0045] The above material property values ​​are applicable to a temperature of 20°C (degrees Celsius). Steels having at least one of the above material property values ​​within the specified range exhibit particularly advantageous properties with regard to the mechanical load-bearing capacity of the impeller made therefrom. This is particularly true for steels having all of the above material property values ​​within the specified value range, in particular for steels having the following properties: a tensile strength of 1070 N / mm 2 Up to 1270N / mm 2 , yield strength is at least 1000N / mm 2 , elastic modulus is 200N / mm 2 , an elongation at break of at least 10%, a hardness of 330 HB to 390 HB and a notched impact toughness of at least 20 J.

[0046] It can also be provided within the scope of the invention that at least one section of the body, in particular the first and / or second section and / or at least one blade, is at least partially made of titanium. It can also be provided that the impeller is made of or consists completely of titanium. This achieves the advantages of a lightweight impeller structure while ensuring a high mechanical load-bearing capacity. In addition, this material has proven to have good processing properties in the context of the use of additive manufacturing methods, in particular cladding.

[0047] It is conceivable that the titanium material contains at least one of the following alloying elements in the following amounts:

[0048] 3% to 10%, preferably 5% to 8%, particularly preferably 5.5% to 6.75% aluminum,

[0049] 1% to 7%, preferably 3% to 6%, particularly preferably 3.5% to 4.5% vanadium.

[0050] The above percentages refer to the mass content (mass fraction) of each alloying element in the titanium material. Titanium materials containing at least one of the above alloying elements within the specified range have significant advantages in terms of processing performance within the scope of the method of the present invention and the load-bearing capacity and durability of the impeller manufactured thereby, while also ensuring the lightweight characteristics of the impeller. It has been proven that titanium materials containing all the above alloying elements within the specified range (especially containing 5.5% to 6.75% aluminum and 3.5% to 4.5% vanadium) can achieve excellent results.

[0051] It is also conceivable within the scope of the invention that the titanium material has at least one of the following material property parameters:

[0052] At least 700N / mm 2 , preferably at least 850 N / mm 2 , particularly preferably at least 895 N / mm 2 The tensile strength (R m ),

[0053] At least 700N / mm 2 , preferably at least 800 N / mm 2 , particularly preferably at least 828 N / mm 2 Yield strength (R p0.2 ),

[0054] 80kN / mm 2 Up to 130kN / mm 2 , preferably 100kN / mm 2 Up to 120kN / mm 2 , particularly preferably 110 kN / mm 2 Up to 115kN / mm 2, especially 114kN / mm 2 The elastic modulus,

[0055] an elongation at break (A5) of at least 5%, preferably at least 8%, particularly preferably at least 10%,

[0056] A hardness (HB30) of 200 HB to 350 HB, preferably 250 HB to 330 HB, particularly preferably 300 HB to 320 HB.

[0057] All the above material property values ​​apply to a temperature of 20°C (degrees Celsius). Titanium materials having at least one of the above material property values ​​within the specified range exhibit particularly advantageous properties in terms of the mechanical load-bearing capacity of the impeller manufactured therefrom and the material processing capabilities. This is particularly true for titanium materials having all the above material property values ​​within the specified value range, in particular for titanium materials having the following properties: a tensile strength of at least 895 N / mm 2 , yield strength is at least 828N / mm 2 , elastic modulus is 114N / mm 2 , the elongation at break is at least 10% and the hardness is 300HB to 320HB.

[0058] It can be provided within the scope of the invention that the method is at least partially automated, in particular carried out by at least one manufacturing robot. It is particularly conceivable that at least steps b) and c) are carried out by a welding robot. It can also be provided that at least step a) or the machining of the impeller, in particular the body, is carried out by an at least semi-automated lathe and / or milling machine.

[0059] It can also be provided that a CAD model of the impeller geometry is used as a basis for at least one step of the method. In other words, it can be provided that, in particular before step a), control instructions for at least one manufacturing robot are defined based on the CAD model of the impeller to at least partially perform at least one step of the method according to the invention. Thus, at least one movement process and / or at least one corresponding movement speed of at least one processing head of at least one manufacturing robot can be defined based on the CAD model in order to at least partially generate or realize the desired impeller geometry.

[0060] Within the scope of the present invention, it is optionally preferred that after step b), at least the following steps are also performed:

[0061] The first and / or second section (11.1, 11.2) is at least partially machined, preferably using a cutting machining method, in order to form an at least partially continuous surface transition between the first and second section (11.1, 11.2).

[0062] In this context, it can be provided that the above-mentioned machining of the first and second sections is achieved by turning, wherein preferably during the turning process, fine machining of at least one surface of the main body is performed in order to achieve an at least partially continuous surface transition across the first and second sections. As a result, the surface quality of the main body is at least partially improved in order to reduce flow losses during operation of the impeller. This can also be an optimal preparation for the subsequent generation of at least one blade, or to produce the final geometry required for the first and second sections with high precision or low tolerances. The machining step can accordingly preferably be performed at least on a section or surface of the main body, in particular the first and / or second section, on which surface the generation of at least one blade will be carried out in step c).

[0063] It can also be provided within the scope of the present invention that, preferably after step c), at least the following steps are also performed:

[0064] Perform at least one heat treatment to improve the mechanical properties of the impeller,

[0065] at least partial machining of the first section and / or the second section and / or at least one blade, preferably using a machining method, in order to at least remove excess material and / or to produce a desired surface quality,

[0066] Dynamically balance the impeller,

[0067] Clean the impeller, preferably by shot blasting.

[0068] In particular for an impeller which is at least partially or completely made of steel, the heat treatment can be carried out as follows: the impeller is at least temporarily heated to a temperature of at least 400° C., preferably at least 500° C., particularly preferably at least 550° C. or exactly or substantially exactly 550° C. It can also be provided that the impeller is kept at the elevated temperature for a period of at least 2 hours, preferably at least 3 hours, particularly preferably at least 4 hours or exactly 4 hours. This allows a particularly advantageous precipitation hardening effect of the steel material and a high mechanical load-bearing capacity of the impeller to be achieved. A particularly advantageous heat treatment variant has proven to be: the impeller is heated to exactly or substantially exactly 550° C. and kept at this impeller temperature for 5 hours. The impeller can then be cooled to room temperature.

[0069] In particular, for an impeller at least partially or completely made of titanium, the heat treatment can be carried out as follows: the impeller is at least temporarily heated to a temperature of at least 450° C., preferably at least 550° C., particularly preferably at least 600° C. or exactly or substantially exactly 600° C. It can also be provided that the impeller is kept at the elevated temperature for a period of at least 1 hour, preferably at least 1.5 hours, particularly preferably at least 2 hours or exactly 2 hours. This allows a high mechanical load-bearing capacity of the impeller to be achieved. A particularly advantageous heat treatment has proven to be that the impeller is heated to exactly or substantially exactly 600° C. and kept at this impeller temperature for 2 hours. The impeller can then be cooled to room temperature. The cooling of the impeller can include cooling the impeller to at least one intermediate temperature and at least temporarily keeping the impeller at this intermediate temperature. It can be provided that the impeller is kept at this intermediate temperature for a period of at least 0.5 hours, preferably at least 1 hour or at least 2 hours. The intermediate temperature can preferably be 200° C. This results in the advantage of further improving the mechanical properties of the impeller.

[0070] "Basically" in this context means that tolerances that may be caused by processing or technology must be taken into account. Thus, for example, slight temporal and / or local temperature fluctuations may occur when heating in a furnace. The workpiece geometry also always has processing-related inaccuracies (tolerances), the order of magnitude of which depends on the method and / or tool and / or machine used.

[0071] In particular for impellers manufactured at least partially or completely from titanium, the impeller heat treatment can be carried out at least partially in a vacuum. It is conceivable that the impeller heat treatment is carried out or can be carried out at least partially in a vacuum furnace. In particular, oxidation of the impeller during the heat treatment and thus disadvantages in the mechanical properties of the impeller can be avoided.

[0072] The advantages of a lightweight impeller configuration and / or a high surface quality to avoid flow losses are obtained by at least partially machining the first section and / or the second section and / or at least one blade to at least remove excess material and / or to produce the required surface quality. The machining can preferably be performed by turning and / or milling.

[0073] With regard to the at least partial machining of the first and / or second section in order to at least remove excess material and / or to produce a desired surface quality, it can be provided that this is carried out at least on the surface of the body or the first and / or second section which is free of blades. In other words, the machining can be carried out at least on the surface of the body or the first and / or second section which is not provided with blades and / or on the surface which is opposite to the surface provided with at least one blade, preferably all blades. The machining can be final machining or for generating the final geometry of the body.

[0074] Regarding the dynamic balancing of the impeller, it can be provided that at least one balancing weight is provided on the impeller to compensate for the balance difference. Preferably, the balancing weight can be mounted by welding. Additionally or alternatively, material can be removed at at least one location on the impeller, preferably using a cutting method (such as drilling or milling) to compensate for the balance difference of the impeller. It can also be provided that during the dynamic balancing process, the impeller is accelerated at least once to a rotation speed of 1000 rpm and then decelerated again, in particular to a rotation speed of 0 rpm.

[0075] Regarding the cleaning of the impeller by shot blasting, it can be provided that spherical or granular shot blasting media are used. In particular, as the shot blasting medium, a stainless steel cast shot blasting medium can be used, or the shot blasting medium can be at least partially, in particular completely, composed or made of stainless steel. It can be provided that the diameter or particle size of the shot blasting medium is between 0.05 mm and 0.6 mm, in particular between 0.09 mm and 0.5 mm. Particularly preferably, the diameter or particle size of the shot blasting medium can be between 0.05 mm and 0.315 mm or between 0.14 mm and 0.5 mm. When using shot blasting media of the above specifications, it has been shown that a particularly high degree of cleanliness and impeller surface quality can be achieved.

[0076] In the context of the invention it can be provided that at least the machining in step a) is carried out using at least one machining method, preferably turning and / or milling. The machining can be at least partially automated, whereby tolerances in the impeller geometry can be reduced.

[0077] It can be provided within the scope of the invention that, preferably before step a) and / or before step b) and / or before step c), at least the following steps are also performed:

[0078] Inserting the blank and / or the first section and / or the second section, which are made of solid material, into the interior of the processing chamber,

[0079] Closed processing room,

[0080] forming an inert atmosphere in the inner cavity of the processing chamber, wherein, in particular, the oxygen content in the inert atmosphere does not exceed 100 ppm, and / or the water content in the inert atmosphere does not exceed 100 ppm,

[0081] • Opening the processing chamber and removing the body or at least a section of the body and / or the impeller.

[0082] It can be provided that the blank is first introduced into the processing chamber and the processing chamber is closed, and then an inert atmosphere is formed in the processing chamber. Alternatively, it is conceivable that an inert atmosphere is first formed in the processing chamber and then the blank is introduced into the processing chamber, in particular via a lock. In addition, the processing chamber can be closed in such a way that an atmosphere exchange between the interior of the processing chamber and the environment outside the processing chamber is prevented or substantially prevented, in particular when the processing chamber is in the closed state.

[0083] It is conceivable within the scope of the present invention that at least one step of the method of the present invention is carried out under an inert atmosphere. In other words, it can be provided that the manufacture of the impeller is at least partially carried out when the impeller is preferably completely or substantially completely surrounded by an inert gas. Preferably, helium or argon can be used as an inert gas. The use of other (different) inert gases or a mixture of at least two inert gases is also included in the concept of the present invention. Due to the processing of the impeller blank or body under an inert atmosphere, oxidation of the workpiece surface can be effectively avoided. In the case of using titanium materials, processing under an inert atmosphere has proven to be advantageous. It can be provided that the oxygen content in the inert atmosphere is 100 ppm (parts per million) or less, in particular 80 ppm or less, preferably 50 ppm or less. In particular, an oxygen content of 50 ppm or less has been shown to be beneficial for effectively avoiding oxidation. It is also conceivable that the water content (H2O) in the inert atmosphere is 100 ppm or less, in particular 80 ppm or less, preferably 50 ppm or less. In particular, a water content of 50 ppm or less has proven to be particularly advantageous for producing high-quality workpieces within the scope of the production method according to the invention.

[0084] It can also be provided that at least one step of the method is performed in an inner cavity of a processing chamber, wherein the inner cavity of the processing chamber is hermetically sealed or substantially hermetically sealed relative to the environment, in particular relative to the environment outside the processing chamber, at least during the execution of at least one method step, and / or is filled or substantially filled with an inert gas. In other words, it can be provided that at least one method step is performed in the processing chamber only after an inert atmosphere has been formed in the processing chamber. This can be achieved by evacuating the processing chamber, in particular using a vacuum pump, and then filling the processing chamber with an inert gas. It is also possible or alternatively possible to purge the processing chamber with an inert gas until the desired inert atmosphere is generated. The processing chamber can be hermetically sealed relative to the environment outside the processing chamber, so that as long as the hermetically sealed closure is maintained, no or substantially no atmosphere exchange occurs between the inner cavity of the processing chamber and the environment outside the processing chamber. The processing chamber can include at least one oxygen sensor, whereby the oxygen concentration in the working space of the processing chamber can be measured.

[0085] It can be provided within the scope of the invention that all method steps or only individual method steps are carried out in the processing chamber. It can also be provided that the workpiece (impeller) is removed from the processing chamber between individual method steps and is introduced into the processing chamber again before a subsequent method step, or that the workpiece remains in the processing chamber during a plurality of method steps carried out in succession. With regard to step a), a blank consisting of solid material can be introduced into the processing chamber before step a), and a first section of the body can be removed from the processing chamber after step a). With regard to step b), a first section of the body can be introduced into the processing chamber before step b), and the body comprising the first and second sections can be removed after step b). With regard to step c), the body can be introduced into the processing chamber before step c), and the impeller comprising the body and at least one blade can be removed after step c).

[0086] It can also be provided within the scope of the invention that the impeller preferably has a diameter of at least 400 mm, in particular at least 450 mm, preferably at least 500 mm, particularly preferably at least 560 mm or exactly or substantially exactly 560 mm after the method according to the invention has been completed. The production method according to the invention has proven to be particularly suitable for impellers with the above-mentioned diameters. This applies in particular to impellers with a diameter of exactly or substantially exactly 560 mm.

[0087] It is also conceivable that the impeller preferably has an axial extension, in particular in the axial direction, of at least 150 mm, in particular at least 170 mm, preferably at least 180 mm, particularly preferably at least 190 or exactly or substantially exactly 190.4 mm after the method according to the invention has been completed. The production method according to the invention has proven to be particularly suitable for impellers with such axial extensions. This applies in particular to impellers with an axial extension of exactly or substantially exactly 190.4 mm.

[0088] It can be provided within the scope of the invention that at least one blade has a greater material thickness on the side facing the main body than on the opposite side or the side facing away from the main body. In other words, at least one blade can have a greater material thickness close to the main body or at its blade root than at its blade tip. Due to the increase in material thickness in the blade root area, a connection with a higher load-bearing capacity between the blade and the main body can be achieved and failure of the blade during operation of the impeller can be avoided. The material thickness can then be gradually reduced from the main body or the blade root to the designed material thickness of the blade. In particular, it is conceivable that at least one blade has twice as much material thickness on its side facing away from the main body or at its blade tip as on its side facing the main body or at its blade root.

[0089] It can also be provided within the scope of the invention that step c) is performed multiple times and that at least one material layer of at least one blade has a smaller layer width than a previously deposited material layer of the same blade. The layer width determines the material thickness of the blade in the blade portion formed by the material layer. The material thickness of the blade can therefore be at least partially varied in a targeted manner by varying the layer width of the deposited material layer, for example in order to increase the mechanical load-bearing capacity of the blade in the root region or on the side facing the main body. In other words, it can therefore be provided that at least one blade has an at least partially varying, preferably at least partially decreasing, material thickness along its extension direction from the main body or its root toward its tip, wherein the material thickness at the root is preferably greater than at the tip.

[0090] The above object is also achieved by an impeller according to the invention comprising a body and at least one blade, wherein the impeller is produced according to the method according to the invention or according to one of claims 1 to 16. With regard to the impeller according to the invention, the same advantages as described with regard to the method according to the invention exist.

[0091] The above object is also achieved by a fluid machine according to the present invention comprising at least one impeller according to claim 17. With respect to the fluid machine, there are the same advantages as described with respect to the impeller. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Further advantages, features and details of the invention are obtained from the following description which describes in detail a number of exemplary embodiments of the invention with reference to the accompanying drawings. The features mentioned in the claims and in the description can be essential to the invention individually or in any combination, wherein:

[0093] Figure 1 is a perspective view of an impeller of the present invention,

[0094] Figure 2 is a cross-sectional view of the impeller of the present invention,

[0095] Figure 3 is a schematic diagram of the method of the present invention,

[0096] Figure 4 is a schematic diagram of the processing according to step a),

[0097] Figure 5 is a schematic diagram of the processing according to step b),

[0098] Figure 6 is a perspective view of the main body of the impeller of the present invention,

[0099] Figure 7 is a schematic diagram of the processing according to step c),

[0100] Figure 8 A blank consisting of solid material is shown in the processing chamber.

[0101] Fig. 9 The schematic structure of the blade is shown. DETAILED DESCRIPTION

[0102] Figure 1 A perspective view of an impeller 10 used in a fluid machine according to the present invention is shown. The impeller 10 is a radially configured impeller 10 and is designed as a radial compressor impeller. The impeller 10 includes a main body 11 and at least one or more blades 12. The main body 11 also includes a first section 11.1 and a second section 11.2, which will be described in detail later. The blades 12 are arranged on the main body 11 of the impeller 10 and are connected to the main body 11 by material bonding. The first section 11.1 and the second section 11.2 are also connected by material bonding. In addition, the first section 11.1, the second section 11.2 and the blades 12 of the impeller 10 are made of the same material or in a uniform material manner. The impeller 10 is flowed through along these blades 12 from the leading edge 18 toward the trailing edge 19.

[0103] Figure 2 A cross-sectional view of an impeller 10 according to the invention is shown, wherein the section plane intersects the rotation axis or center axis of the impeller 10. The impeller 10 is designed such that a fluid flow will or can flow into the impeller 10 in an axial direction X and a fluid flow will or can flow out of the impeller 10 in a radial direction R. The axial direction X is oriented parallel to the rotation axis M of the impeller 10 and the radial direction R is oriented orthogonal to the rotation axis M of the impeller 10. The rotation axis M is arranged coaxially to the rotation axis M1 of the first section 11.1 and the rotation axis M2 of the second section 11.2.

[0104] Figure 3 A schematic diagram of a method 100 for manufacturing a fluid machine impeller 10 or an impeller used in a fluid machine according to the present invention is shown, wherein the impeller comprises a body 11 and at least one blade 12, wherein the body 11 and the blade 12 are connected by material bonding, and wherein at least the following steps are preferably performed in the following order:

[0105] a) machining a blank 1 consisting of solid material to produce a first section 11 . 1 of the body 11 ,

[0106] b) applying at least one material layer 13 to the first section 11 . 1 of the body 11 using an additive manufacturing method to at least partially generate the second section 11 . 2 of the body 11 ,

[0107] c) applying at least one material layer 13 to the first section 11 . 1 and / or the second section 11 . 2 to at least partially generate at least one blade 12 on the body 11 using an additive manufacturing method.

[0108] The method 100 will be explained in detail below. Figure 4The processing of a blank 1 according to the invention according to step a) is schematically shown. The blank 1 is shown on the left and consists of solid material. The blank 1 is processed in step a) preferably using a cutting method, so that the blank 1 generates a main body 11 in the form of a Figure 4 The first section 11.1 is shown on the right. The first section 11.1 of the body 11 is designed to be rotationally symmetrical. For the sake of clarity, the area where material is removed from the blank 1 to produce the geometry of the first section 11.1 is shown on the right. Figure 4 The first section 11.1 is indicated by a dashed line in the illustration.

[0109] Figure 5 The processing of the body 11 or the first section 11 . 1 of the body 11 according to the invention according to step b) is schematically shown. Figure 5 1 shows on the left side a first section 11.1 of the body 11 after the processing in step a). On the right side a body is shown after the processing in step b), comprising the first section 11.1 and the second section 11.2. In step b), a plurality of material layers 13 are applied 102 to the first section 11.1 of the body 11 in order to generate or build up the second section 11.2 of the body 11, in particular layer by layer. This is achieved by using an additive manufacturing method so that the second section 11.2 is continuously built up from the surface of the first section 11.1. Here, the first section 11.1 and the second section 11.2 form at least one common surface 15 of the body 11, on which surface at least one blade 12 can or will be subsequently generated.

[0110] Here, the second section 11.2 is produced on the first section 11.1 by laser deposition welding and thus by material building, wherein the second section 11.2 is produced by successive application 102 of a plurality of material layers 13 or weld beads. Thus, a materially bonded connection is obtained between the first section 11.1 and the second section 11.2.

[0111] The added material used to generate the second section 11.2 during the build-up welding process is formed of a uniform material with the solid material blank 1 or the first section 11.1 of the body 11. Therefore, the first section 11.1 and the second section 11.2 of the body 11 are formed of a uniform material.

[0112] Can Figure 5 1 . It can be seen that the second section 11.2 completely surrounds the first section 11.1. The second section 11.2 is designed to be rotationally symmetrical, and the rotation axis or center axis M2 of the second section 11.2 is arranged coaxially with the rotation axis or center axis M1 of the first section 11.1.

[0113] from Figure 5 Together, at least partial machining of the first section 11 . 1 and the second section 11 . 2 can be performed in order to ensure a continuous surface transition and / or a high surface quality of the surface 15 .

[0114] Figure 6 For explanation purposes, a perspective view of the main body 11 is shown, which includes a first section 11.1 and a second section 11.2. Here, the first section 11.1 and the second section 11.2 form the entire main body 11. Figure 6 Starting from the illustrated body geometry, one or more blades 12 can now be produced on the surface 15 of the body 11 .

[0115] Figure 7 The processing of the body 11 or the first section 11.1 and the second section 11.2 of the body 11 according to step c) is schematically shown according to the invention. Figure 7 The left side of the figure shows the main body 11 after the processing in step b) has been performed. The right side shows the impeller 10 after the processing in step c), which comprises the main body 11 consisting of a first section 11.1 and a second section 11.2 and at least one blade 12. In step c), a plurality of material layers 13 are applied 103 to the first section 11.1 and the second section 11.2 of the main body 11, so as to preferably generate or form at least one blade 12, in particular a plurality of blades 12, on the main body 11 in layers. This is performed by using an additive manufacturing method, so as to continuously form at least one blade 12 from the surface 15 of the main body 11. Here, at least one blade 12 extends at least partially across the first section 11.1 and the second section 11.2 of the main body.

[0116] Here, at least one blade 12 is produced by laser cladding and thus by material building on the surface 15 of the body 11 formed by the first section 11.1 and the second section 11.2, wherein the blade 12 is produced by successively applying 103 a plurality of material layers 13 or weld beads. Thus, a materially bonded connection is achieved between the body 11 and at least one blade 12, in particular all blades 12. The blades 12 are Figure 7 The geometric shapes are only schematically depicted in a simplified manner.

[0117] The added material used to generate the second section 11.2 during the build-up welding process is formed in a manner of using the same material as the first section 11.1 and the second section 11.2 of the body 11. Therefore, the first section 11.1 and the second section 11.2 and the blades 12 of the body 11 are formed in a manner of using the same material.

[0118] from Figure 7 Initially, further machining steps may be performed on the impeller 10. Thus, at least one at least partial machining of the first section 11.1 and / or the second section 11.2 and / or at least one blade 12 may be performed to remove excess material. It is also possible to perform a heat treatment of the impeller 10, perform a dynamic balancing of the impeller 10 and / or perform a cleaning of the impeller 10.

[0119] Figure 8 The blank 1 made of solid material is schematically shown in the inner chamber 14.1 of the processing chamber 14, so that at least step a) can be performed in the processing chamber 14, but in particular at least steps b) and c) can also be performed. The inner chamber 14.1 can be hermetically sealed relative to the external environment of the processing chamber 14, or can be hermetically sealed when performing at least one method step. Therefore, the execution of at least one processing step can be carried out under an inert atmosphere, which is previously formed by evacuating the inner chamber 14.1 or filling the inner chamber 14.1 with an inert gas. By processing the impeller blank or body 11 under an inert atmosphere, oxidation of the material workpiece surface can be effectively avoided.

[0120] Fig. 9 A greatly simplified view of the blade 12 on the main body surface 15 is shown, wherein the viewing direction is along the center axis M towards the leading edge 18 . Fig. 9 The illustration shown should only be used to explain the multilayer structure of the blade 12. The blade 12 consists of a plurality of material layers 13, which are successively applied to the surface 15 or the respective preceding material layer 13 using an additive manufacturing method. By applying the individual material layers 13, a material growth is achieved on the blade 12 or on the body 11, whereby the geometry of the blade 12 can be generated reliably and material-savingly.

[0121] The blade 12 has a higher material thickness T on the side facing the body 11 or at the blade root 17 than on the side facing away from the body 11 or at the blade tip 16. Due to the increase in the material thickness in the region of the blade root 17, a more load-bearing connection between the blade 12 and the body 11 can be achieved and failure of the blade 12 during operation of the impeller 10 can be avoided.

[0122] The higher material thickness in the region of the blade root 17 is achieved by first depositing one or more material layers 13 with a first layer width T in step c) and subsequently depositing at least one material layer 13 with a second layer width T, wherein the second layer width T is smaller than the first layer width T. By varying the layer width T of the material layers 13 deposited on the body 11 , the material thickness T of the blade 12 can vary starting from the body 11 along the extension direction of the blade 12 between the blade root 17 and the blade tip 16 .

[0123] Reference numerals list

[0124] 1 Blank

[0125] 10 Impeller

[0126] 11 Subject

[0127] 11.1 The first section

[0128] 11.2 The second section

[0129] 12 blades

[0130] 13 Material Layer

[0131] 14 Processing Room

[0132] 14.1 Inner cavity

[0133] 15 Surface

[0134] 16 Leaf tip

[0135] 17 Yegen

[0136] 18 Leading Edge

[0137] 19 trailing edge

[0138] 100 Methods

[0139] 101 Processing

[0140] 102 Apply

[0141] 103 Apply

[0142] M Center axis / rotation axis

[0143] M1 Center axis / rotation axis

[0144] M2 Center axis / rotation axis

[0145] R Radial

[0146] T Material thickness / layer width

[0147] X-axis

Claims

1. A method (100) for manufacturing a fluid machinery impeller (10), the impeller comprising a body (11) and at least one blade (12), wherein: The body (11) and the blade (12) are connected in a material-joined manner, and at least the following steps are preferably performed in the following order: a) machining (101) a blank (1) consisting of solid material to produce a first section (11.1) of the body (11), b) applying (102) at least one material layer (13) to the first section (11.1) of the body (11) using an additive manufacturing method to at least partially generate a second section (11.2) of the body (11), c) applying (103) at least one material layer (13) to the first section (11.1) and / or the second section (11.2) using an additive manufacturing method to at least partially generate at least one blade (12) on the body (11).

2. The method (100) according to claim 1, characterized in that: The application (102, 103) of the material layer (13) in step b) and / or step c) is performed by build-up welding, preferably laser build-up welding.

3. The method (100) according to any one of the preceding claims, characterized in that The rotation axis (M1) of the first section (11.1) and the rotation axis (M2) of the second section (11.2) are coaxially arranged, and / or the second section (11.2) at least partially surrounds the first section (11.1).

4. The method (100) according to any one of the preceding claims, characterized in that The first section (11.1) and the second section (11.2) of the body (11) are at least partially composed of the same material, and / or at least one section (11.1, 11.2) of the body (11) and the at least one blade (12) are at least partially composed of the same material.

5. The method (100) according to any one of the preceding claims, characterized in that At least one section (11.1, 11.2) of the body (11) and / or the at least one blade (12) at least partially consists of martensitic precipitation hardening steel.

6. The method (100) according to claim 5, characterized in that: The steel contains at least one of the following alloying elements, the content of which is: 10 to 20%, preferably 13 to 18%, particularly preferably 15 to 17%, of chromium, 1% to 7%, preferably 2% to 6%, particularly preferably 3% to 5% nickel, 1% to 7%, preferably 2% to 6%, particularly preferably 3% to 5% copper.

7. The method (100) according to claim 5 or 6, characterized in that: The steel has at least one of the following material characteristic parameters: 900N / mm 2 Up to 1400N / mm 2 , preferably 1000N / mm 2 Up to 1300N / mm 2 , particularly preferably 1070N / mm 2 Up to 1270N / mm 2 The tensile strength (R m ), At least 800N / mm 2 , preferably at least 900 N / mm 2 , particularly preferably at least 1000 N / mm 2 Yield strength (R p0.2 ), 100kN / mm 2 Up to 300kN / mm 2 , preferably 150kN / mm 2 Up to 250kN / mm 2 , particularly preferably 180 kN / mm 2 Up to 220kN / mm 2 , especially 200kN / mm 2 The elastic modulus, an elongation at break (A5) of at least 5%, preferably at least 8%, particularly preferably at least 10%, A hardness (HB30) of 250 HB to 450 HB, preferably 300 HB to 400 HB, particularly preferably 330 HB to 390 HB, A notched impact toughness of at least 10 J, preferably at least 15 J, particularly preferably at least 20 J.

8. The method (100) according to any one of the preceding claims, characterized in that At least one section (11.1, 11.2) of the body (11) and / or the at least one blade (12) are at least partially made of titanium.

9. The method (100) according to claim 8, characterized in that: The titanium material contains at least one of the following alloying elements, the content of which is: 3% to 10%, preferably 5% to 8%, particularly preferably 5.5% to 6.75% aluminum, 1% to 7%, preferably 3% to 6%, particularly preferably 3.5% to 4.5% vanadium.

10. The method (100) according to claim 8 or 9, characterized in that: The titanium material has at least one of the following material characteristic parameters: At least 700N / mm 2 , preferably at least 850 N / mm 2 , particularly preferably at least 895 N / mm 2 The tensile strength (R m ), At least 700N / mm 2 , preferably at least 800 N / mm 2 , particularly preferably at least 828 N / mm 2 Yield strength (R p0.2 ), 80kN / mm 2 Up to 130kN / mm 2 , preferably 100kN / mm 2 Up to 120kN / mm 2 , particularly preferably 110 kN / mm 2 Up to 115kN / mm 2 , especially 114kN / mm 2 The elastic modulus, an elongation at break (A5) of at least 5%, preferably at least 8%, particularly preferably at least 10%, A hardness (HB30) of 200 HB to 350 HB, preferably 250 HB to 330 HB, particularly preferably 300 HB to 320 HB.

11. The method (100) according to any one of the preceding claims, characterized in that Preferably, after step b), at least the following steps are performed: The first and / or second section (11.1, 11.2) is at least partially machined, preferably using a cutting machining method, at least to form an at least partially continuous surface transition across the first and second section (11.1, 11.2) and / or to produce a required surface quality.

12. The method (100) according to any one of the preceding claims, characterized in that Preferably, after step c), at least the following steps are performed: performing at least one heat treatment to improve the mechanical properties of the impeller (10), preferably using a machining method to machine the first section (11.1) and / or the second section (11.2) and / or the at least one blade (12) at least partially, at least to remove excess material (11) and / or to produce a desired surface quality, Dynamically balancing the impeller (10), Clean the impeller (10), preferably by shot blasting.

13. The method (100) according to any one of the preceding claims, characterized in that At least the machining (101) in step a) is performed by using at least one cutting machining method, preferably turning and / or milling.

14. The method (100) according to any one of the preceding claims, characterized in that Preferably, before step a) and / or before step b) and / or before step c), at least the following steps are further performed: The blank (1) made of solid material and / or the first and / or second section are introduced into the interior (14.1) of the processing chamber (14), generating an inert atmosphere in the inner cavity (14.1) of the processing chamber (14), In particular, the oxygen content in the inert atmosphere does not exceed 100 ppm, and / or the water content in the inert atmosphere does not exceed 100 ppm.

15. The method (100) according to any one of the preceding claims, characterized in that The impeller (10) has a diameter of at least 400 mm and / or an axial extension of at least 150 mm.

16. The method (100) according to any one of the preceding claims, characterized in that Said step c) is performed a plurality of times and at least one material layer (13) of said at least one blade (12) has a smaller layer width (T) than a previously applied material layer (13) of the same blade (12).

17. An impeller (10), comprising a body (11) and at least one blade (12), wherein: The impeller (10) is manufactured according to the method (100) according to any one of claims 1 to 16.

18. A fluid machine comprising at least one impeller (10) according to claim 17.

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