Combined additive and subtractive manufacturing of bladed rotors

Abstract

Embodiments of bladed rotors and methods for manufacturing bladed rotors are provided herein. The method for manufacturing a bladed rotor includes providing a workpiece including a first rotor blade segment. The first rotor blade segment includes a first platform portion at a radially outward end of the first rotor blade segment. The method also includes forming a second rotor blade segment by additive manufacturing, removing a side portion of the first platform portion, and removing the side portion of the second rotor blade segment, thereby retaining a second platform portion at the radially outward end of the second rotor blade segment.

Description

Technical Field

[0001] Embodiments herein relate to bladed rotors and methods of producing bladed rotors. Background Art

[0002] Conventional bladed rotors are manufactured by separately producing a hub or disk and a plurality of rotor blades. The blades are connected to the disk by means of a positive engagement (eg by means of a fir-tree profile).

[0003] The manufacturing cost of the bladed rotor based on the above conventional method is high. In particular, the manufacturing cost of the form-fitting joints on both the hub or disk and the blades is high and accounts for a major share of the cost of the entire bladed rotor.

[0004] An alternative method could be based on casting or molding a workpiece and manufacturing its bladed rotor in a subtractive manner, i.e. removing material from the workpiece by cutting or machining, so that the rotor blades and the hub or disk remain. Another alternative method could be based on casting or molding a workpiece including the hub or disk and the rotor blades, and subsequently removing material from the workpiece by cutting or machining.

[0005] Typically, rotor blades are arranged close together, limiting the accessibility of subtractive manufacturing tools. In particular, the area at the base of the blade, or in other words, the area close to the hub or disk, is either inaccessible or accessible only with specialized tools. In the latter case, these specialized tools must have a high aspect ratio (defined as the ratio of tool length to tool diameter). Compared to standard tools, these specialized tools with high aspect ratios are expensive and often lead to inferior manufacturing results due to vibration / chatter caused by cutting forces. Summary of the Invention

[0006] In short, a method of producing a bladed rotor and a bladed rotor are provided to overcome at least some of the above limitations. This object is achieved by means of a method according to claim 1 and a bladed rotor according to claim 10.

[0007] According to an embodiment, a method for manufacturing a bladed rotor comprising a plurality of rotor blades is provided. The method comprises the following sequence of steps:

[0008] A) A workpiece is provided that includes a first rotor blade segment. The first rotor blade segment includes a first platform portion on a radially outward end of the first rotor blade segment.

[0009] B1) Forming a second rotor blade segment radially outward on the first platform portion by additive manufacturing.

[0010] B2) Removing the side portions of the first platform portion and removing the side portions of the second rotor blade segment, whereby the second platform portion remains on the radially outward end portion of the second rotor blade segment.

[0011] Optionally, the sequence of steps B1) and B2) can be repeated N≥1 times. Thus, in the (n)th repetition, n=1...N, the (n+2)th rotor blade segment and the (n+2)th platform portion are formed respectively, and the side portion of the (n+1)th platform portion is removed. In the case where steps B1) and B2) are not repeated, N=0;

[0012] The method further comprises the following steps:

[0013] C1) forming an (N+3)th rotor blade segment radially outward on the (N+2)th platform portion by additive manufacturing;

[0014] C2) Remove the side of the (N+2)th platform portion and remove the side of the (N+3)th rotor blade segment

[0015] According to an embodiment, a bladed rotor is provided. The bladed rotor includes a hub and a plurality of rotor blades. Each rotor blade includes a plurality of rotor blade segments adjacent to one another. The rotor blade segments have respective main body regions and interface regions, the interface regions being disposed adjacent to radially outward ends of the respective rotor blade segments. Furthermore, an average grain size difference between the interface region and the main body region of at least one of the rotor blade segments is at least 10%, preferably at least 20%, and / or an average hardness difference between the interface region and the main body region of at least one of the rotor blade segments is at least 5%, preferably at least 10%.

[0016] Those skilled in the art will recognize additional features and advantages upon reading the following detailed description and upon viewing the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The components in the figures are not necessarily drawn to scale, but rather emphasize the principles of the present invention. Additionally, in the figures, like reference numerals designate corresponding parts. In the figures:

[0018] Figure 1 A cross section of a bladed rotor according to an embodiment of the present disclosure is shown.

[0019] Figure 2 A cross section of a bladed rotor according to an embodiment of the present disclosure is shown.

[0020] Figure 3 A cross section of a bladed rotor according to an embodiment of the present disclosure is shown.

[0021] Figure 4 A cross section of a bladed rotor according to an embodiment of the present disclosure is shown.

[0022] Figure 5 A cross section of a bladed rotor according to an embodiment of the present disclosure is shown.

[0023] Figure 6 A cross section of a bladed rotor according to an embodiment of the present disclosure is shown.

[0024] Figure 7 A cross section of a bladed rotor according to an embodiment of the present disclosure is shown.

[0025] Figure 8 A cross section of a bladed rotor according to an embodiment of the present disclosure is shown.

[0026] Figure 9 A cross section of a rotor blade according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0027] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments of the invention.

[0028] As used herein, the terms “having,” “comprising,” “including,” “comprising,” and the like are open-ended terms indicating the presence of stated elements or features, but do not preclude additional elements or features.

[0029] It should be understood that other embodiments may be utilized and that structural or logical changes may be made without departing from the scope of the present invention. Therefore, the following detailed description should not be understood in a limiting sense, and the scope of the present invention is defined by the appended claims. The embodiments described herein use specific language, which should not be interpreted as limiting the scope of the appended claims.

[0030] According to an embodiment, a method for manufacturing a bladed rotor 100 is provided. The bladed rotor 100 comprises a plurality of rotor blades 200, 201, 202, 203. Each of the rotor blades may comprise a plurality of rotor blade segments 110, 120.

[0031] Each rotor blade 200, 201, 202, 203 may define a build direction (or manufacturing direction). The build direction may substantially correspond to the radial direction of the bladed rotor 100. In some embodiments, the rotor blades 200, 201 may be curved. In this case, the build direction may be a combination of a radial direction and a transverse direction, with the transverse direction being perpendicular to the radial direction. In the build direction or radial direction of the bladed rotor 100, each of the rotor blade segments 110, 120, 130, 140 may be arranged adjacent to one or two other rotor blade segments. (Each) rotor blade segment may substantially or completely span the entire cross-sectional area of the rotor blade 200, 201 across the build direction or radial direction. In other words, within a limited range of the radial direction or build direction, the rotor blade 200, 201 may consist of or substantially consist of one rotor blade segment 110, 120, 130, 140.

[0032] The transverse direction is understood to be perpendicular to the radial direction and may include the axial direction of the bladed rotor 100. As disclosed herein, a side portion refers to a portion of a component extending in a transverse direction.

[0033] The bladed rotor 100 may comprise a hub 300, 301. In particular, the hub 300, 301 may be disc-shaped.

[0034] The bladed rotor 100 may be an axial turbine. The bladed rotor 100 may be a radial turbine. The bladed rotor 100 may be an exhaust turbine. The bladed rotor 100 may be a mixed flow turbine. The bladed rotor 100 may be a compressor.

[0035] The method comprises a sequence of three steps: A, B and C.

[0036] Step A) of the method comprises providing a workpiece 10. Step A) of the method may be considered as providing or manufacturing the innermost portion of the bladed rotor 100. For example, Figure 2 and Figure 5 An embodiment of a workpiece 10 is shown.

[0037] Workpiece 10 includes a first rotor blade segment 110. First rotor blade segment 110 includes a first platform portion 111. First platform portion 111 (and likewise all further platform portions 121, 131, 141, ..., as further described below) may include side portions. Furthermore, first platform portion 111 may include an interior portion. The interior portion may span a cross-sectional area that is substantially the same as the cross-sectional area of the portion of first rotor blade segment 110 that does not include first platform portion 111. First platform portion 111 (and likewise all further platform portions 121, 131, 141, ..., as further described below) may be largely considered an auxiliary or temporary component for manufacturing purposes. After manufacturing is completed, at least portions of first platform portion 111, in particular the side portions, may not be included in bladed rotor 100.

[0038] The first platform portion 111 is arranged on the radially outer end 114 of the first rotor blade segment 110. For example, Figure 2 and Figure 5 An embodiment of a first platform portion 111 and a radially outward end portion 114 of a first rotor blade segment 110 is shown.

[0039] The side portions of the first platform portion 111 may extend by less than 1 cm, preferably less than 2 mm, in a transverse direction, preferably in all transverse directions. In one embodiment, the first rotor blade segment 110 including the side portions of the first platform portion 111 may extend further in a transverse direction, preferably in all transverse directions, by up to 1 cm, preferably by up to 4 mm, compared to the first rotor blade segment 110 not including the first platform portion 111.

[0040] According to an embodiment, the side portions of the first platform portion 111 may partially or preferably completely surround the transverse circumference of the first rotor blade segment 110. Preferably, the side portions of the first platform portion 111 completely cover the radially outermost portion of the first rotor blade segment 110. The above-described properties of the first platform portion 111 may be similarly or equally applicable to the other platform portions 121, 131, 141, ..., as further described below.

[0041] The forming of the workpiece 10 may comprise the step A1): providing a hub 300, 301. The workpiece 10 comprising the first rotor blade segment 110 may be formed in a number of different ways.

[0042] According to an embodiment, step A2) may be performed after step A1), wherein A2) includes removing a portion of the hub 301 to form the first rotor blade segment 110. In this embodiment, the radial dimensions of the hub 300 of the bladed rotor 100 are reduced compared to the radial dimensions of the hub 301 provided in step A1). Removing the portion of the hub 301 may be performed such that the first platform portion 111 remains on the radially outward end 114 of the first rotor blade segment 110. Removing portions of a component may also be referred to as subtractive manufacturing.

[0043] Figure 5 A cross section of a bladed rotor is schematically shown after step A2), ie after forming the workpiece 10. The dashed line illustrates the hub 301 after step A1). The solid line shows the hub 300 together with the first rotor blade segment 110 after step A2).

[0044] According to another embodiment, step A2′) can be performed after step A1), and A2′) includes forming the first rotor blade segment 110 radially outward on the hub 300 by additive manufacturing. Thereafter, the side of the first rotor blade segment 110 can be removed, whereby the first platform portion 111 remains on the radially outward end 114 of the first rotor blade segment 110. Removing the side of the first rotor blade segment 110 can be accompanied by removing a portion of the hub 300.

[0045] Figure 1 A cross section of the bladed rotor is schematically shown after a part of step A2 ′) has been completed, ie after the first rotor blade segment 110 has been formed radially outwardly on the hub 300 . Figure 2 A cross section of a bladed rotor is schematically shown after completion of step A2'), ie after formation of the workpiece 10. The dashed lines illustrate the hub 300 and the first rotor blade segment 110 before parts are removed.

[0046] The method for producing a bladed rotor 100 further comprises a step B). Step B) of the method can be regarded as producing a middle portion of the bladed rotor 100 or producing a middle portion of the rotor blade 200 .

[0047] Step B) includes a step B1 of forming the second rotor blade segment 120 radially outward on the first platform portion 111 by additive manufacturing. For example, Figure 3 and Figure 6 A cross section of a bladed rotor 100 is illustrated after step B1) according to an embodiment of the present disclosure.

[0048] Furthermore, step B) includes a step B2 of removing a side portion of the first platform portion 111 or substantially removing the entire first platform portion 111. The side portion of the first platform portion 111 may be removed such that the first platform portion 111 has no or substantially no laterally protruding portion compared to the remaining portion of the first rotor blade segment 110 not including the first platform portion 111. Step B2) also includes removing a side portion of the second rotor blade segment 120. The side portion of the second rotor blade segment 120 may be removed such that the second platform portion 121 remains on the radially outward end portion 124 of the second rotor blade segment 120. For example, Figure 4 and Figure 7 An embodiment of a cross section of a bladed rotor 100 after step B2) according to an embodiment of the present disclosure is illustrated. Dashed lines illustrate the portion of the first platform portion 111 and the portion of the second rotor blade segment 120 that were removed in step B2).

[0049] According to an embodiment, the sequence of steps B1) and B2) can be repeated one or more times, i.e., N ≥ 1 times. This allows the third rotor blade segment 130, the fourth rotor blade segment 140, and so on to be formed. Similarly, by repeating the sequence of steps B1) and B2), the third platform portion, the fourth platform portion, and so on are formed. Each additional (third, fourth, ...) rotor blade segment is formed radially outwardly on the previous (second, third, ...) platform portion, and in particular, not on the first platform portion 111. Furthermore, the side portions of the second platform portion 121, the side portions of the third platform portion, and so on can be removed. In other words, by repeating the sequence of steps B1) and B2), in the (n)th repetition, where n = 1 ... N, the (n+2)th rotor blade segment and the (n+2)th platform portion are formed, respectively, and the side portions of the (n+1)th platform portion are removed. If the sequence of steps B1) and B2) is not repeated, N = 0.

[0050] The sequence of steps B1) and B2) can be repeated any number of times. According to one exemplary embodiment, the sequence of steps B1) and B2) is repeated once. According to another exemplary embodiment, the sequence of steps B1) and B2) is repeated nine times.

[0051] The method for producing a bladed rotor 100 further comprises a step C). Step C) of the method may be regarded as producing an outer part, in particular a final or outermost part, of the bladed rotor 100 or of a rotor blade 200 .

[0052] Step C) includes forming the (N+3)th rotor blade segment radially outward on the (N+2)th platform portion by additive manufacturing. According to an embodiment, step C1) is performed in a manner substantially similar to step B1). In one embodiment, the (N+2)th platform portion can be considered the second-to-last platform portion, and the (N+3)th rotor blade segment can be considered the last rotor blade segment.

[0053] Furthermore, step C) includes a step C2 of removing a side portion of the (N+2)th platform portion. The side portion of the (N+2)th platform portion may be removed such that the (N+2)th platform portion has no or substantially no laterally protruding portion compared to the remaining portion of the (N+2)th rotor blade segment excluding the (N+2)th platform portion. Step C2) may further include removing a side portion of the (N+3)th rotor blade segment. In an embodiment, the side portion of the (N+3)th rotor blade segment may be removed such that no (N+3)th platform portion remains on the radially outward end of the (N+3)th rotor blade segment. The side portion of the (N+3)th rotor blade segment may be removed such that the (N+3)th rotor blade segment has no or substantially no laterally protruding portion compared to the (N+2)th rotor blade segment.

[0054] Removal of parts of the hub 301 and / or parts of the first or further rotor blade segments 110 , 120 . . . and / or parts of the first or further platform portions 111 , 121 . . . may be performed by machining, preferably wherein the machining comprises rough milling and fine milling.

[0055] Additive manufacturing itself is known to those skilled in the art. For example, standard terminology for additive manufacturing techniques is disclosed in ASTM F2792-12a.

[0056] Additive manufacturing can include providing a build material. The build material can be one of a powder and a wire. According to an embodiment, the build material can include a nickel-containing alloy (e.g., at least 50 wt % nickel), in particular a nickel-based alloy. Additionally or alternatively, the hubs 300, 301 can include a nickel-containing alloy (e.g., at least 50 wt % nickel), in particular a nickel-based alloy. For example, the build material can include the alloy NiCr22Mo9Nb (also known as alloy 625, 2.4856) and / or the alloy NiCr19NbMo (also known as alloy 718, 2.4668). For example, the hubs 300, 301 may include the alloy NiCr22Mo9Nb (also known as alloy 625, 2.4856) and / or the alloy NiCr19NbMo (alloy 718, 2.4668) and / or the alloy NiCrAlMoTiNbZr (also known as alloy 713LC, UNS N07713) and / or the alloy NiFeCr12Mo (also known as alloy 901, 2.4975). According to an embodiment, the construction material may include an iron-containing alloy (e.g., at least 50 wt% iron), in particular an iron-based alloy. Additionally or alternatively, the hubs 300, 301 may include an iron-containing alloy (e.g., at least 50 wt% iron), in particular an iron-based alloy. In an embodiment, the construction material and the hubs 300, 301 may include the same alloy.

[0057] Additive manufacturing can include melting a build material using focused thermal energy. The focused thermal energy can be selected from the group consisting of a laser beam, an electron beam, an electric arc, and a plasma arc. Preferably, the focused thermal energy is a laser beam. Where the focused thermal energy is an electric arc, the build material can be a wire.

[0058] The method for manufacturing a bladed rotor 100 according to embodiments of the present disclosure is advantageous for a number of reasons. The manufacture of the bladed rotor 100 does not require the production of form-fit joints, nor does it require the rotor blades to be constructed or attached to a hub or disk using form-fit joints. Advantageously, the method according to embodiments of the present disclosure enables the production of bladed rotors at a lower cost. Production costs can be reduced by up to 30%. The rotor blades 200, 201 are fused to the hub 300, 301 using concentrated thermal energy, thereby resulting in a more robust bladed rotor 100 that is less prone to cracking or breaking than bladed rotors that include form-fit joints.

[0059] Furthermore, by manufacturing the rotor blade in multiple, sequential steps, and particularly by removing the side portions of each rotor blade segment prior to forming the subsequent rotor blade segment, access is gained to portions of the rotor blade that would not be accessible later (particularly after all segments of the rotor blade have been formed) using low-cost or standard tooling. Advantageously, no specialized and / or expensive tooling having a high aspect ratio is required to manufacture the bladed rotor 100 according to embodiments of the present disclosure. In many applications, it is appropriate or desirable to manufacture rotor blades comprising a construction material having poor machinability (particularly, substantial amounts of nickel-based alloys). By manufacturing the rotor blade in multiple, sequential steps, and particularly by individually removing the side portions of each rotor blade segment, the poor machinability of some construction materials is less of a concern.

[0060] Advantageously, by subtractively forming the rotor blade segment (removing its side portions) so that the platform portion remains on the rotor blade segment before the subsequent rotor blade segment is additively manufactured, inaccuracies are avoided. The platform portion protects or shields the preceding rotor blade segment from weld spatter caused by concentrated heat energy and build material, which negatively impacts the surface quality of rotor blade 200 and / or hub 300. Furthermore, concentrated heat energy results in a heat-affected zone (HAZ) on the preceding rotor blade segment. A HAZ can cause thermal deformation and, therefore, inaccuracies. The platform portion serves as a support and locally separates the preceding rotor blade segment from the HAZ. In other words, heat is primarily distributed throughout the platform portion, thereby avoiding thermal deformation of the preceding rotor blade segment. Furthermore, by subtractively forming the rotor blade segment (removing its side portions) so that the platform portion remains on the rotor blade segment before the subsequent rotor blade segment is additively manufactured, the production of transitions between "twisted" portions of the rotor blade is advantageously facilitated, i.e., when the build direction is a combination of radial and transverse directions (i.e., not completely straight throughout its radial extent). In particular, in the case of “twisted” sections, the surface quality of the transition regions between consecutive rotor blade segments may be improved by enabling smooth transition regions.

[0061] The present disclosure relates to a method for manufacturing a bladed rotor 100 comprising a plurality of rotor blades 200. The above embodiments relate to a sequence of steps for manufacturing one rotor blade. The sequence of steps for manufacturing a first rotor blade 200 can be performed in any order compared to the sequence of steps for manufacturing a second rotor blade 201.

[0062] According to one embodiment, the method may further include performing one (preferably all) of the steps selected from A2), A2′), B1), B2), C1), and C2) on all rotor blades 200 before performing subsequent steps. For example, step A2′) may be performed on all rotor blades 200, 201 before performing step B1). Figure 8 The cross section of a bladed rotor 100 according to an embodiment of the present disclosure is shown, wherein a first rotor blade segment 110 ( Figure 8 The figure shows a cross section of a bladed rotor 100 and therefore only parts of some of the rotor blades are shown). It is also possible to carry out one or even part of all steps selected from A2), A2′), B1), B2), C1), C2) on all rotor blades 200 before carrying out a successive part of the steps. Figure 8 An embodiment is illustrated wherein the first rotor blade segment (110) is formed for all rotor blades 200, 201, 202, 203 before the sides of the first rotor blade segment 110 are removed.

[0063] In an embodiment, the method may further include performing all manufacturing steps selected from A2), A2′), B1), B2), C1), and C2) on the first rotor blade 200 before performing any manufacturing steps selected from A2), A2′), B1), B2), C1), and C2) on the second rotor blade 201. The first rotor blade 200 may even be completely formed before performing any manufacturing steps for forming the second rotor blade 201.

[0064] According to an embodiment, a method for manufacturing a turbocharger including a bladed rotor (100) is provided. The bladed rotor (100) includes a plurality of rotor blades and is manufactured according to any one of the embodiments disclosed herein.

[0065] According to an embodiment, a bladed rotor 100 is provided. The bladed rotor 100 may include a hub 300 and a plurality of rotor blades 200, 201, 202, 203. Each rotor blade 200 may include a plurality of rotor blade segments 110, 120, 130, 140 adjacent to each other.

[0066] Each of the rotor blade segments 110, 120, 130, 140 may have a respective main body region 112, 122, 132, 142. Furthermore, each of the rotor blade segments 110, 120, 130, 140 may include an interface region 113, 123, 133, 143 disposed adjacent to a radially outward end 114, 124, 134 of the respective rotor blade segment 110, 120, 130, 140. The interface region 113 , 123 , 133 , 143 may be arranged adjacent to the body region 112 , 122 , 132 , 142 of the same rotor blade segment 110 , 120 , 130 , 140 and adjacent to the body region 112 , 122 , 132 , 142 of an adjacent rotor blade segment 110 , 120 , 130 , 140 .

[0067] For example, Figure 9 The cross section of the rotor blade 200 is shown, including an interface region 113 disposed adjacent a radially outward end 114 of the first rotor blade segment 110. The interface region 113 is disposed adjacent the first body region 112 of the first rotor blade segment 110 and adjacent the second body region 122 of the second rotor blade segment 120.

[0068] The interface region 113 , 123 , 133 , 143 may extend in the radial direction by less than 1 mm, preferably less than 200 μm.

[0069] The bladed rotor 100 according to embodiments of the present disclosure differs from known bladed rotors 100, inter alia, in the attachment or mounting of the rotor blade 200 to the hub 300, 301 and / or in the properties of the rotor blade 200. The rotor blade 200 of the bladed rotor 100 according to the present disclosure may have at least one property that differs between the interface region 113, 123, 133, 143 and the main body region 112, 122, 132, 142 of at least one of the rotor blade segments 110, 120, 130, 140.

[0070] According to an embodiment, the bladed rotor 100 is provided as a single piece. In particular, the bladed rotor 100 is provided without any form-fitting engagement between the hub 300 and the rotor blades 200 .

[0071] In one embodiment, the average grain size differs by at least 10%, preferably at least 20%, between the interface region 113, 123, 133 and the main body region 112, 122, 132 of at least one of the rotor blade segments 110, 120, 130. The average grain size is determined according to ASTM E112-13, Section 11 (planar measurement or Jeffries' (3) procedure). Preferably, the average grain size in the interface region 113, 123, 133 is at least 10%, preferably at least 20%, lower than the main body region 112, 122, 132, 142 of at least one of the rotor blade segments 110, 120, 130, 140.

[0072] In one embodiment, the average hardness of at least one of the rotor blade segments 110, 120, 130, 140 differs by at least 5%, preferably by at least 10%, between the interface region 113, 123, 133 and the main body region 112, 122, 132, 142. Methods for determining hardness and average hardness are known to those skilled in the art. Preferably, the average hardness is determined according to DIN EN ISO 6507. The average hardness can be determined by recording a micrograph and selecting a micrograph having a predetermined size (e.g., 5000 mm). 2 ), for example by delineating a circle or a rectangle, preferably, the average hardness in the interface region 113, 123, 133 is at least 5% greater, preferably at least 10% greater, than in the main body region 112, 122, 132 of at least one of the rotor blade segments 110, 120, 130.

[0073] The properties of the respective interface regions 113, 123, 133 may be the result of an advantageous manufacturing method and / or the result of subjecting the interface regions 113, 123, 133 to heat generated by concentrated thermal energy during the manufacturing process of at least two respective method steps. The bladed rotor 100 is obtained by additive manufacturing. Preferably, the bladed rotor 100 is manufactured according to any of the embodiments disclosed herein.

[0074] The bladed rotor 100 may be an axial turbine or a radial turbine. The bladed rotor 100 may be an exhaust turbine. The bladed rotor 100 may be a mixed flow turbine. The bladed rotor 100 may be a compressor. According to one embodiment, a turbocharger is provided. The turbocharger includes a bladed rotor (100) according to any embodiment disclosed herein.

[0075] The dimensions and values disclosed herein should not be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to represent both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "100 μm" means "approximately 100 μm."

Claims

1. A method for manufacturing a bladed rotor (100), the bladed rotor (100) comprising a plurality of rotor blades (200, 201, 202, 203), the method comprising the following sequence of steps: A) providing a workpiece (10) comprising a first rotor blade segment (110), wherein the first rotor blade segment (110) comprises a first platform portion (111), the first platform portion (111) being on a radially outward end portion (114) of the first rotor blade segment (110); B1) forming a second rotor blade segment (120) radially outward on the first platform portion (111) by additive manufacturing; B2) removing a side portion of the first platform portion (111) and removing a side portion of the second rotor blade segment (120), whereby the second platform portion (121) remains on the radially outward end portion (124) of the second rotor blade segment (120); wherein the sequence of steps B1) and B2) is repeated N≥1 times, wherein in the (n)th repetition, n=1…N, the (n+2)th rotor blade segment and the (n+2)th platform portion are formed, respectively, and the side portion of the (n+1)th platform portion is removed, and wherein in the case where steps B1) and B2) are not repeated, N=0; as well as C1) forming an (N+3)th rotor blade segment radially outward on the (N+2)th platform portion by additive manufacturing; C2) removing the side of the (N+2) platform portion, and removing the side of the (N+3) rotor blade segment; The side portion of each platform portion at least partially surrounds a transverse perimeter of its corresponding rotor blade segment, and the transverse direction is perpendicular to the radial direction.

2. The method according to claim 1, wherein providing the workpiece (10) in step A) comprises: A1) providing a hub (300, 301); and A2) or A2'), wherein: A2) removing a portion of the hub (301) to form the first rotor blade segment (110); A2') The first rotor blade segment (110) is formed radially outward on the hub (300) by additive manufacturing, and a side portion of the first rotor blade segment (110) is subsequently removed, whereby the first platform portion (111) remains on the radially outward end portion (114) of the first rotor blade segment (110).

3. The method according to claim 1, wherein the side portion of the first platform portion (111) extends less than 1 cm along the transverse direction.

4. The method according to claim 3, wherein the side portion of the first platform portion (111) extends less than 2 mm along the transverse direction.

5. The method of claim 2, wherein the additive manufacturing comprises providing a build material; and melting the build material by means of concentrated thermal energy.

6. The method of claim 5, wherein the focused thermal energy is one of a laser beam, an electron beam, an electric arc, and a plasma arc. The method of claim 6 , wherein the focused thermal energy is a laser beam.

8. The method of claim 5, wherein the construction material comprises an alloy containing nickel and / or iron; and / or wherein the hub (300, 301) comprises an alloy containing nickel and / or iron.

9. The method according to claim 1 or 2, wherein before performing the subsequent steps, one step selected from the steps A), B1), B2), C1), C2) is performed on the plurality of rotor blades (200, 201, 202, 203); if A2) or A2') is present, one step selected from the steps A), A2) or A2'), B1), B2), C1), C2) is performed on the plurality of rotor blades (200, 201, 202, 203).

10. The method according to claim 1 or 2, wherein the manufacturing steps A), B1), B2), C1), and C2) are performed on a first rotor blade (200) and then the manufacturing steps are performed on a second rotor blade (201); if A2) or A2') is present, the manufacturing steps A), A2) or A2'), B1), B2), C1), C2) are performed on the first rotor blade (200) and then the manufacturing steps are performed on the second rotor blade (201).

11. The method according to claim 2, wherein the removal of a portion of the hub (301) and / or a portion of the first rotor blade segment (110) or the second rotor blade segment (120) and / or a portion of the first platform portion (111) or the second platform portion (121) can be performed by means of machining.

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