(19)
(11)EP 3 369 937 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
29.12.2021 Bulletin 2021/52

(21)Application number: 16859730.0

(22)Date of filing:  24.10.2016
(51)International Patent Classification (IPC): 
F04D 29/22(2006.01)
B23K 9/16(2006.01)
B23K 101/00(2006.01)
F04D 29/02(2006.01)
B23K 9/038(2006.01)
B23K 9/02(2006.01)
F04D 29/28(2006.01)
F04D 29/62(2006.01)
F01D 5/04(2006.01)
B23K 9/00(2006.01)
(52)Cooperative Patent Classification (CPC):
F04D 29/22; F05D 2230/10; F04D 29/023; B23K 9/0026; F05D 2230/40; F04D 29/026; F04D 29/62; B23K 2101/001; F05D 2230/232; B23K 9/038; F04D 29/28
(86)International application number:
PCT/JP2016/081401
(87)International publication number:
WO 2017/073500 (04.05.2017 Gazette  2017/18)

(54)

METHOD OF MANUFACTURING IMPELLER

VERFAHREN ZUR HERSTELLUNG EINES LAUFRADS

PROCÉDÉ DE FABRICATION D'IMPULSEUR


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 28.10.2015 JP 2015211703
29.09.2016 JP 2016190866

(43)Date of publication of application:
05.09.2018 Bulletin 2018/36

(73)Proprietor: Ebara Corporation
Tokyo 144-8510 (JP)

(72)Inventors:
  • YAMADA, Esao
    Tokyo 144-8510 (JP)
  • ORITA, Kentaro
    Tokyo 144-8510 (JP)
  • YAMAKAWA, Takashi
    Tokyo 144-8510 (JP)

(74)Representative: Carstens, Dirk Wilhelm 
Wagner & Geyer Partnerschaft mbB Patent- und Rechtsanwälte Gewürzmühlstraße 5
80538 München
80538 München (DE)


(56)References cited: : 
EP-A1- 2 047 938
JP-A- H01 205 889
JP-A- S61 262 465
JP-A- H01 205 889
JP-A- S61 262 465
JP-B2- S5 523 705
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    Technical Field



    [0001] The present invention relates to a method of manufacturing an impeller.

    Background Art



    [0002] Since old times, the fabrication of structures has been performed using welding technology. Structures to be manufactured by welding include not only large structures such as ships and bridges, but also precision machines, as exemplified by bodies of automobiles and trains and impellers of rotating machines. For rotating machines such as pumps, compressors and turbines, in recent years, with the size reduction and high performance of the machines, an tip-opening between a hub and a cover (see an tip-opening b2 between a hub and a cover in Figure 7(D)) has become narrow and the precision requirement has become strict.

    [0003] When the tip-opening between the hub and the cover is several tens of millimeters or narrower, it is not possible to insert a welding rod to the back of a blade (in the deep direction with respect to the paper plane in the case of Figure 7(D)), and therefore, it is difficult to apply a normal welding. In response, conventionally, in the case of welding a blade in such a narrow tip-opening that it is not possible to insert the welding rod to the back of the blade, a slot welding is used

    [0004] Attention is also drawn to JP S61 262 465 A, which shows a method for welding a structure having a narrow gap. For maintaining a narrow gap space during a welding process, a deformation preventive material consisting of a water soluble material is packed into spaces to be formed as gaps between members before welding the members together. After the welding the structure is immersed in water to dissolve the deformation preventive material. Furthermore, JP H01 205 889 A relates to a method for joining an impeller of a centrifugal compressor, etc. to a main plate by performing vacuum diffusion welding

    Summary of Invention


    Problem to be Solved



    [0005] However, in the case of welding the hub to the blade in a state where the outer circumference side of the hub and the outer circumference side of the cover are fixed by a fixture and where the inner circumference side of the hub and the inner circumference side of the cover are not fixed by a fixture (for example, see step 6 of Figure 9), a large deformation occurs in the hub after the welding. Specifically, the large deformation, as shown in Figure 7(D), is a drop of the inner circumference side of the hub 2 to the side of the cover 3. As the cause for the deformation, there can be the following matter. That is, since the welding is performed in the state where the outer circumference side is fixed but the inner circumference side is not fixed, it is possible that the contractive force at the time of natural cooling after the welding increases at a position closer to the inner circumference side while the fixed portion is a supporting point and the largest deformation occurs at a boss portion (see a boss portion 18 in Figure 11) that is closest to the inner circumference side.

    [0006] Further, in the case of welding the hub to the blade in a state where the hub and the cover are not fixed by a fixture both on the outer circumference side and on the inner circumference side, the deformation of the hub 2 occurs both on the outer circumference side and on the inner circumference side. Similarly, in the case of welding the cover to the blade, a large deformation occurs in the cover after the welding. Conventionally, such a deformation is eliminated by processing, and in the case of an acceptable degree, the structure can be adopted as a product. However, in recent years, since the requirement for the dimensional accuracy of the blade is high, such a deformation is not within a degree in which the deformation is accepted by processing.

    [0007] The present invention has been made in view of the above problem, and has an object to provide a method of manufacturing an impeller that makes it possible to reduce the deformation of the hub or cover due to the welding.

    Means for solving the Problem



    [0008] In accordance with the present invention, a method as set forth in claims 1, 11, 12 and 17 is provided. Further embodiments are inter alia disclosed in the dependent claims.

    [0009] In a method of manufacturing an impeller according to one aspect of the present invention, the method inter alia comprises:

    a step of forming a cover that is provided with a plurality of blades;

    a step of disposing a core on the cover such that the core is interposed between the blades;

    a step of disposing a hub on the blades, the hub being a plate on which grooves conforming to shapes of the blades are formed; and

    a step of welding the hub and the blades, wherein through-holes conforming to the shapes of the blades are provided on the core, such that the blades are fitted in the core when the core is disposed.



    [0010] Thereby, the core physically restrains the deformation of the hub due to the contractive force at the time of natural cooling after the welding, and therefore, it is possible to manufacture an impeller in which the deformation amount of the hub is small. Accordingly, it is possible to improve yield rate, to significantly improve production efficiency, and to reduce manufacturing cost.

    [0011] A method of manufacturing an impeller according to one aspect of the present invention, in the above method of manufacturing an impeller,
    the method further comprising a step of breaking and removing the core, when a temperature of the hub becomes lower than a predetermined temperature after the step of welding the hub and the blades.

    [0012] Thereby, the core is broken when the action of the contractive force on the hub is stopped, and therefore, it is possible to manufacture an impeller in which a space is provided between the hub and the cover, without the deformation of the hub.

    [0013] A method of manufacturing an impeller according to one aspect of the present invention, in any one of the above method of manufacturing an impeller, wherein

    a vent hole is provided on the core, and

    the method further comprises a step of affixing a tape over a gap between the hub and the core and filling an inert gas from the vent hole into a space among the hub, the cover and the core, before the step of welding the hub and the blades.



    [0014]  Thereby, by affixing the tape, it is possible to prevent the inert gas from leaking out of the gap among the hub, the cover and the core, and therefore, it is possible to surely prevent the oxidation of a welding metal.

    [0015] A method of manufacturing an impeller according to one aspect of the present invention, in any one of the above method of manufacturing an impeller, wherein
    the through-holes of the core have shapes similar to the shapes of the blades, and are wider than the blades in circumferential width.

    [0016] Thereby, it is possible to insert the core into interspaces of the blades.

    [0017] A method of manufacturing an impeller according to one aspect of the present invention, in any one of the above method of manufacturing an impeller, wherein

    the number of the through-holes provided on the core is the same as the number of the blades, and

    in the step of disposing the core, the core is disposed by overlaying the core on the cover such that horizontal positions of the plurality of blades roughly coincide with horizontal positions of the corresponding through-holes.



    [0018]  Thereby, it is possible to insert the core into each interspace of the blades.

    [0019] A method of manufacturing an impeller according to one aspect of the present invention, in any one of the above method of manufacturing an impeller, wherein

    the cover and the core have disk shapes, and

    in the step of disposing the core on the cover, the core is disposed such that a central axis of the core roughly coincides with a central axis of the cover.



    [0020] Thereby, the cover and the core are coaxially disposed.

    [0021] A method of manufacturing an impeller according to one aspect of the present invention, in any one of the above method of manufacturing an impeller, wherein

    the hub and the core have disk shapes, and

    in the step of disposing the hub on the blades, the hub is disposed such that a central axis of the hub roughly coincides with a central axis of the cover.



    [0022] Thereby, the hub and the cover are coaxially disposed.

    [0023]  A method of manufacturing an impeller according to one aspect of the present invention, in any one of the above method of manufacturing an impeller, wherein
    the core is formed using a raw material that is used in precision casting.

    [0024] Thereby, it is possible to reduce the unevenness of the surface of the core. Therefore, even when the unevenness corresponding to the shape of the surface of the core is generated by the welding on a surface of the hub that contacts with the core, the unevenness of the surface can be reduced because the unevenness of the surface of the core is reduced.

    [0025] A method of manufacturing an impeller according to one aspect of the present invention, in any one of the above method of manufacturing an impeller, wherein
    the cover is a cover that is carved integrally with the blades by machining.

    [0026] Thereby, it is possible to inhibit the blades from being taken off from the cover, because there is no joint between the blades and the cover.

    [0027] A method of manufacturing an impeller according to one aspect of the present invention, in any one of the above method of manufacturing an impeller, wherein

    holes for welding are provided in the grooves of the hub, and

    in the step of welding the hub and the blades, a welding material is poured through the holes for welding, and the hub and the blades are welded.



    [0028] Thereby, it is possible to weld the hub and the blades even for an impeller having such a narrow space that it is hard to insert a welding rod.

    [0029] A method of manufacturing an impeller according to one aspect of the present invention, in any one of the above method of manufacturing an impeller, wherein
    the impeller is an impeller of a rotating machine.

    [0030] Thereby, it is possible to manufacture an impeller in which the deformation amount of the hub is small.

    [0031] A method of manufacturing an impeller according to one aspect of the present invention, the method comprising:

    a step of forming a hub that is provided with a plurality of blades;

    a step of disposing a core on the hub such that the core is interposed between the blades;

    a step of disposing a cover on the blades, the cover being a plate on which grooves conforming to shapes of the blades are formed; and

    a step of welding the cover and the blades, wherein
    through-holes conforming to the shapes of the blades are provided on the core, such that the blades are fitted in the core when the core is disposed.



    [0032] Thereby, the core physically restrains the deformation of the cover due to the contractive force at the time of natural cooling after the welding, and therefore, it is possible to manufacture an impeller in which the deformation amount of the cover is small. Accordingly, it is possible to improve yield rate, to significantly improve production efficiency, and to reduce manufacturing cost.

    [0033] A method of manufacturing an impeller according to 13th aspect of the present invention, the method comprising:

    a step of forming a hub that is provided with a plurality of blades;

    a step of disposing a plurality of divided cores on the hub, such that each of the divided cores is disposed at each interspace of the adjacent blades;

    a step of disposing a cover on the hub and the divided plates; and

    a step of welding the cover and the blades.



    [0034] Thereby, by using the divided cores, each of the divided cores has light, and it is possible to avoid the collapse due to its own weight. Further, it is possible to decrease the bending moment that is generated in the divided core when the divided core is held up, and to secure the strength allowing works such as the fabrication of the divided core and welding setup (the assembly of the divided core). Since the divided core has a small size, the deformation amount during hardening treatment is also small, and combined with the division structure, it is possible to improve the workability for mounting (assembling) the divided core to the impeller. Further, even when the divided core becomes unusable due to deformation or damage, one of the divided cores only needs to be replaced because of the division structure, and therefore, the influence on fabrication cost is decreased.

    [0035] A method of manufacturing an impeller according to a 14th aspect of the present invention, in the method of manufacturing an impeller according to the 13th aspect, wherein

    a hollow space is formed at a center of the hub,

    the divided cores protrude to an inner circumference side than the hub, and

    the method comprises a step of providing inner circumference spacers at interspaces of the adjacent divided cores on the inner circumference side, in the step of disposing the divided cores.



    [0036] Thereby, it is possible to perform the positioning of the divided cores.

    [0037] A method of manufacturing an impeller according to a 15th aspect of the present invention, in the method of manufacturing an impeller according to the 14th aspect, wherein

    heights of the inner circumference spacers when the inner circumference spacers are provided are lower than heights of the divided cores, and

    in the step of welding the cover and the blades, an inert gas is supplied from an inner circumference side, such that the inert gas flows through a passage that is formed between the hub and the cover.



    [0038] Thereby, it is possible to provide a slight gap between a surface of the divided core and a surface of the divided core, and it is possible to supply the inert gas from the gap. Therefore, it is possible to avoid a vent hole formation work by which the core is damaged at a high risk.

    [0039]  A method of manufacturing an impeller according to a 16th aspect of the present invention, in the method of manufacturing an impeller according to any one of the 13th to 15th aspect, wherein

    a hollow space is formed at a center of the hub,

    the method further comprises a step of mounting a centering fixture in the hollow space formed in the hub, after the step of forming the hub and before the divided cores are disposed, and

    in the step of disposing the divided cores, the divided cores are disposed such that back surfaces of inner circumference sides of the divided cores contact with a front surface of the centering fixture.



    [0040] Thereby, the divided cores support the inner circumference side of the cover, and therefore, it is possible to avoid the inner circumference side of the cover provided on the cores from falling down due to the welding.

    [0041] A method of manufacturing an impeller according to a 17th aspect of the present invention, in the method of manufacturing an impeller according to any one of the 13th to 16th aspect, the method further comprising a step of respectively disposing outer circumference spacers at interspaces of the adjacent blades on outer circumference sides of the divided cores, in the step of disposing the divided cores, wherein
    in the step of welding the cover and the blades, an inert gas is supplied from an inner circumference side, such that the inert gas flows through a passage that is formed between the hub and the cover.

    [0042] Thereby, the presence of the outer circumference spacers can restrain the inert gas from leaking to the outside. It is possible to make the inert gas reach a penetration bead that is generated at the time of the welding of the blades, and it is possible to avoid the penetration bead from being oxidized.

    [0043] A method of manufacturing an impeller according to a 18th aspect of the present invention, in the method of manufacturing an impeller according to any one of the 13th to 17th aspect, wherein

    the plurality of blades are provided from a center of the hub at an equal angular interval, and shapes of the blades are roughly the same as each other, and

    shapes of the divided cores are roughly the same as each other.



    [0044] Thereby, as a wooden pattern for molding the divided cores, only a single set having a small size is needed, and the divided cores can be formed with the same wooded pattern. Further, since the wooden pattern for molding the divided cores has a small size, it is possible to use a small and inexpensive additive manufacturing device for resin shaping, in the fabrication of the wooded pattern, and it is possible to fabricate a wooden pattern (resin pattern) having a relatively high shape accuracy at low cost in a short time. Therefore, it is possible to make the divided cores at low cost in a short time. Alternatively, with the additive manufacturing device, it is possible to mass-produce the same divided cores, based on the same 3D model.

    [0045] A method of manufacturing an impeller according to a 19th aspect of the present invention, in the method of manufacturing an impeller according to any one of the 13th to 18th aspect, wherein
    wherein
    thicknesses of the divided cores are smaller than heights of the blades with respect to a front surface of the hub, by a predetermined length.

    [0046] Thereby, top surfaces of the blades melt by the welding, and thereby, the blades contract so that the heights become roughly the same as the thicknesses of the divided cores. Therefore, it is possible to prevent unnecessary force from being applied to the divided cores.

    [0047]  A method of manufacturing an impeller according to one aspect of the present invention, the method comprising:

    a step of forming a cover that is provided with a plurality of blades;

    a step of disposing a plurality of divided cores on the cover, such that each of the divided cores are disposed at each interspace of the adjacent blades;

    a step of disposing a hub on the cover and the divided cores; and

    a step of welding the hub and the blades.



    [0048] Thereby, by using the divided cores, each of the divided cores has light, and it is possible to avoid the collapse due to its own weight. Further, it is possible to decrease the bending moment that is generated in the divided core when the divided core is held up, and to secure the strength allowing works such as the fabrication of the divided core and welding setup (the assembly of the divided core). Since the divided core has a small size, the deformation amount during hardening treatment is also small, and combined with the division structure, it is possible to improve the workability for mounting (assembling) the divided core to the impeller. Further, even when the divided core becomes unusable due to deformation or damage, one of the divided cores only needs to be replaced because of the division structure, and therefore, the influence on fabrication cost is decreased.

    Advantageous Effects of Invention



    [0049] According to the present invention, the core physically restrains the deformation of the hub due to the contractive force at the time of natural cooling after the welding, and therefore, it is possible to manufacture an impeller in which the deformation amount of the hub is small. Accordingly, it is possible to improve yield rate, to significantly improve production efficiency, and to reduce manufacturing cost.

    Brief Description of Drawings



    [0050] 

    Figure 1 is a perspective view showing the outline of manufacturing steps for an impeller 1 according to the embodiment.

    Figure 2 is a cross-sectional view showing the detail of the manufacturing steps for the impeller 1 according to the embodiment.

    Figure 3 is a cross-sectional view showing manufacturing steps following Figure 2.

    Figure 4 is a cross-sectional view showing manufacturing steps following Figure 3.

    Figure 5(A) is a top view of an impeller in the state of Figure 1(D).

    Figure 5(B) is a cross-sectional view taken from line BB' in Figure 5(A).

    Figure 6 is a perspective view of a cover 3 according to the comparative example.

    Figure 7 is a schematic view showing manufacturing steps for the impeller 21 according to the comparative example, using cross sectional views taken from line CC' in Figure 6.

    Figure 8 is a detail view showing manufacturing steps for the impeller 21 according to the comparative example, using cross sectional views taken from line DD' in Figure 6.

    Figure 9 is a detail view showing manufacturing steps following Figure 8.

    Figure 10 is a detail view showing manufacturing steps following Figure 9.

    Figure 11 is a diagram for describing the contraction amount of the impeller 21 according to the comparative example.

    Figure 12 is a perspective view of a hub before and after a centering fixture is mounted.

    Figure 13 is a perspective view of the hub before and after divided cores are disposed.

    Figure 14 is a perspective view of one divided core as viewed from the back side.

    Figure 15 is an exploded perspective view of the divided cores as viewed from the back side, for describing inner circumference spacers and outer circumference spacers.

    Figure 16 is a perspective view of the hub when the inner circumference spacers, the outer circumference spacers and the divided cores are disposed.

    Figure 17 is a partial perspective view of the hub taken along a polyline L1 and a straight line L2 in Figure 16.

    Figure 18 is a perspective view of the hub before and after a cover is disposed.

    Figure 19 is a flowchart showing an example of the method of manufacturing the impeller according to the second embodiment.


    Description of Embodiments


    <Comparative Example>



    [0051] For making the object of the present invention clearer, a method of manufacturing an impeller 21 of a rotating machine according to a comparative example will be described with use of Figure 6 to Figure 10, before the description of a method of manufacturing an impeller of a rotating machine according to an embodiment of the present invention. A technique for welding blades in a narrow tip-opening between a hub and a cover by a slot welding will be described.

    [0052]  Figure 6 is a perspective view of a cover 3 according to the comparative example. Figure 7 is a schematic view showing manufacturing steps for the impeller 21 according to the comparative example, using cross sectional views taken from line CC' in Figure 6. Figure 8 is a detail view showing manufacturing steps for the impeller 21 according to the comparative example, using cross sectional views taken from line DD' in Figure 6. Figure 9 is a detail view showing manufacturing steps following Figure 8. Figure 10 is a detail view showing manufacturing steps following Figure 9.

    [0053] The cover 3 shown in Figure 6 is obtained by carving the cover 3 integrated with blades 4, from a forging material. As shown in Figure 6, a plurality of blades 4 is provided on the cover 3. As shown in Figure 7(A), which is a CC' cross-sectional view of Figure 6, the blades 4 are provided so as to be roughly perpendicular to the cover 3. At this time, as shown in step 1 of Figure 8, which is a DD' cross-sectional view of Figure 6, the blades 4 are provided on the cover 3.

    [0054] Subsequently, as shown in step 2 of Figure 8, a centering fixture 8 made of steel is placed at the center of the cover 3. Subsequently, as shown in step 3 of Figure 8 and step 4 of Figure 9, the hub 2 is placed on the cover 3. In the hub 2, grooves 5 for the slot welding of the blades 4 and the hub 2 are provided on a surface on the side opposite to a surface that contacts with the blades 4. As shown in Figure 7(B), the shape of the grooves 5 is a similar shape to upper surfaces (bonding surfaces) of the blades 4, and is slightly larger than that of the blades 4. The hub 2 is placed such that the horizontal positions of the blades 4 roughly coincide with the horizontal positions of the grooves 5. As shown by a broken line in step 3 of Figure 8, a plurality of holes 9 for welding is provided on the grooves 5.

    [0055] Next, as shown in step 5 of Figure 9, an outer circumference portion of the hub 2 and an outer circumference portion of the cover 3 are fixed by a fixture 7. The fixture 7 has a zonal plate shape, and by the fixture 7, the outer circumference side of the hub 2 and the outer circumference side of the cover 3 are fixed over the whole circumference. At the same time, as shown by welding portions 11 for fixing, a welding material is poured from the holes 9 provided on the grooves 5. The hub 2 and the blades 4 are temporarily joined by welding, the fixture 7 and the hub 2 are temporarily joined by welding, and the fixture 7 and the cover 3 are temporarily joined by welding.

    [0056]  Next, as shown in step 6 of Figure 9, an electric welding is performed along the groove 5. Specifically, for example, the slot welding is performed from the inner circumference side of the groove 5 toward the outer circumference side, at an electric current of 60 A to 190 A. On this occasion, the welding material is poured from the holes 9 for welding shown in Figure 7(C), and the hub 2 and the blades 4 are welded. By the welding, a structure shown in Figure 7(C) is obtained. As shown in Figure 7(C), in a cross section taken from line CC' in Figure 6, there is a deformation by which the hub 2 drops to the side of the cover 3 between the blade 4 and the blade 4.

    [0057] Next, as shown in step 7 of Figure 10, an annealing is performed at 500 to 600°C for about three hours, in order to remove distortion. Next, as shown in step 8 of Figure 10, a spot fixed by the fixture 7 and the like is eliminated, and a surface processing is performed in accordance with design dimensions. Thereby, the impeller 21 according to the comparative example is completed, and the impeller having a cross section shown in Figure 7(D) is obtained.

    [0058] As shown in Figure 7(D), in a cross section taken from line CC' in Figure 6, there is a deformation by which the hub 2 drops to the side of the cover 3 between the blade 4 and the blade 4. Figure 11 is a diagram for describing the contraction amount of the impeller 21 according to the comparative example. The welding is performed in a state where the outer circumference side is fixed and the inner circumference side is a free end, and therefore, as shown in Figure 11, the contraction of the inner circumference side is larger than that of the outer circumference side, so that the deformation of the inner circumference side is larger than that of the outer circumference side.

    <Embodiment of Present Invention>



    [0059] In response, in an embodiment of the present invention, at the time of the welding, a core is interposed between the hub 2 and the cover 3, and the hub 2 is physically restrained from dropping to the side of the cover 3 between the blade 4 and the blade 4. In the following, a method of manufacturing an impeller 1 of a rotating machine according to the embodiment will be described with reference to Figure 1 to Figure 5. Here, for example, the rotating machine is a pump, a turbine, a compressor, or an air blower.

    [0060] Figure 1 is a perspective view showing the outline of manufacturing steps for an impeller 1 according to the embodiment. Figure 2 is a cross-sectional view showing the detail of the manufacturing steps for the impeller 1 according to the embodiment. Figure 3 is a cross-sectional view showing manufacturing steps following Figure 2. Figure 4 is a cross-sectional view showing manufacturing steps following Figure 3. Figure 5(A) is a top view of an impeller in the state of Figure 1(D). Figure 5(B) is a cross-sectional view taken from line BB' in Figure 5(A).

    [0061] First, the cover 3 provided with the blades 4 is formed. Specifically, by machining, the cover 3 is carved from a forging material integrally with the blades 4. As shown in Figure 1(A), the cover 3 has a disk shape. As shown in step 1 of Figure 2, the cover 3 is placed. Next, as shown in Figure 1(B) and step 2 of Figure 2, a centering fixture 8 is mounted at the center of the cover 3.

    [0062] Next, as shown in Figure 1(C) and step 3 of Figure 2, a core 10 is disposed on the cover 3 such that the core 10 is interposed between the blade 4 and the blade 4. Here, the core 10 has a disk shape, and through-holes (slits) 14 conforming to the shapes of the blades 4 are provided on the core 10, such that the blades 4 are fitted in the core 10 when the core 10 is disposed. The number of the through-holes 14 provided on the core 10 is the same as the number of the blades 4.

    [0063] The specific disposing method is shown as follows. The core 10 is disposed by overlaying the core 10 on the cover 3 such that the horizontal positions of the plurality of blades 4 roughly coincide with the horizontal positions of the corresponding through-holes 14. On this occasion, the core 10 is disposed such that the central axis of the core 10 roughly coincides with the central axis of the cover 3. In the embodiment, the through-holes 14 of the core 10 have shapes similar to the shapes of the blades 4, and are wider than the blades 4 in circumferential width. Thereby, the blades 4 are fitted in the core 10.

    [0064] As shown in Figure 1(C) and Figure 5(B), a vent hole 15 is provided in the core 10. The vent hole 15 is a hole for back shield gas, and is a hole through which an inert gas such as nitrogen (N2) and argon (Ar) flows for the purpose of the prevention of the oxidation of a welding metal. Here, the welding metal is a metal that melts during the welding and solidifies when the welding is performed.

    [0065] The core 10 is subjected to high temperatures at the time of the welding, and therefore, it is preferable that the core 10 be made of a high-temperature-resistant material. Further, the core 10 is formed using a raw material that is used in precision casting. Here, in precision casting, there is a little unevenness on a cast surface and the like. Thereby, it is possible to reduce the unevenness of the surface of the core 10. Therefore, even when the unevenness corresponding to the shape of the surface of the core 10 is generated by the welding on a surface of the hub 2 that contacts with the core 10, the unevenness of the surface can be reduced because the unevenness of the surface of the core 10 is reduced.

    [0066] Further, the core 10 needs to be removed after the welding, and therefore, it is preferable that the core 10 be made of a raw material that can be physically broken readily. In the embodiment, as an example, the core 10 is formed using a material described in Patent Literature 1. By using such a material, the physical removal of the core 10 becomes easy.

    [0067] Next, as shown in Figure 1(D) and step 4 of Figure 2, the hub 2 is disposed on the blades 4. As shown in Figure 1(D), grooves 5 conforming to the shapes of the blades are formed on the hub 2, and a plurality of holes 9 for welding shown by a broken line in step 4 of Figure 2 is provided on the grooves 5. Further, the hub 2 has a disk shape, and in the step of disposing the hub 2 on the blades 4, the hub 2 is disposed such that the central axis of the hub 2 roughly coincides with the central axis of the cover 3.

    [0068]  As shown in Figure 5(B), the core 10 is inserted between the hub 2 and the cover 3. Thereby, it is possible to physically restrain the deformation of the hub 2 caused by the solidification and contraction of the welding metal due to the welding. Further, an inner circumference portion 17 of the hub 2 is supported by the centering fixture 8 and the core 10. Thereby, it is possible to physically restrain the deformation of the inner circumference portion 17 caused by the solidification and contraction of the welding metal due to the welding.

    [0069] As shown in step 5 of Figure 3, a tape 16 is affixed over the gap between the hub 2 and the core 10, and the inert gas is filled from the vent hole 15 (see Figure 5(B)) into the space among the hub 2, the cover 3 and the core 10. Here, the tape 16 has heat-resistant property. By affixing the tape 16, it is possible to prevent the inert gas from leaking out of the gap among the hub 2, the cover 3 and the core 10, and therefore, it is possible to surely prevent the oxidation of the welding metal. Thereafter, end portions of the blades 4 and the grooves 5 of the hub 2 are fixed by welding, to be temporarily joined (see step 5 of Figure 3). Thereby, welding portions 11 for fixing are formed.

    [0070] Thereafter, as shown in step 6 of Figure 3, the welding material is poured through the plurality of holes 9 for welding, and the hub 2 and the blades 4 are welded. Thereby, it is possible to weld the hub and the blades even for an impeller having such a narrow space that it is hard to insert a welding rod. This welding is a so-called slot welding. The welding current at this time is 60 A to 190 A, for example. By this welding, a welding portion 12 is formed. Thereafter, as shown in step 7 of Figure 3, the tape 16 is peeled off, after step 6 of Figure 3, which is a welding step.

    [0071] Next, as shown in step 7 of Figure 3, the welded impeller is annealed. The condition of the annealing varies depending on plate thickness or the like. In the embodiment, as an example, the annealing is performed at 500 to 600°C for about three hours. After the annealing, as shown in step 8 of Figure 4, the centering fixture 8 playing a role in positioning is removed. Next, as shown in step 9 of Figure 4, when the hub 2 becomes lower than a predetermined temperature, the core 10 is physically broken and removed. Thereby, the core is broken when the action of the contractive force on the hub is stopped, and therefore, it is possible to manufacture a structure in which a space is provided between the hub and the cover, without the deformation of the hub. Next, as shown in step 10 of Figure 4, a process of eliminating an outer circumference portion 19 shown in step 9 of Figure 4, and the like are performed so that design dimensions are obtained. Thereby, the impeller 1 according to the embodiment is completed.

    [0072] As a result of the measurement with a precision measurement device, in the comparative example, a concave deformation of about 0.5 to 1 mm was observed at a spot where the deformation of the inner circumference side was largest. On the other hand, in the embodiment, at the corresponding spot of the inner circumference side, the deformation hardly appeared, or even the deformation appeared, the deformation was a very small deformation of about 0.1 mm.

    [0073] As shown in Figure 11, in the comparative example, in the hub 2, the contraction amount increases and the deformation amount increases in the direction from the outer circumference side to the boss portion 18 of the inner circumference side. Particularly, at the boss portion 18 of the hub 2, because of a free end, a large contraction occurs and the deformation is large. On the other hand, in the embodiment, the core 10 is inserted between the hub 2 and cover 3 of the impeller 1. Thereby, the core 10 can physically restrain the deformation due to the contractive force at the time of natural cooling after the welding, and therefore, it is possible to manufacture an impeller in which the deformation amount of the hub 2 is small. Accordingly, it is possible to improve yield rate, to significantly improve production efficiency, and to reduce manufacturing cost.

    [0074] In the embodiment, the method of manufacturing the impeller 1 of the rotating machine has been described, but without being limited to this, the use of the core can be also applied to a method of manufacturing another structure. Particularly, it is preferable that the use of the core be applied to a structure having such a narrow space that it is hard to insert the welding rod.

    [0075] In the embodiment, the blades are provided on the cover, but without being limited to this, the blades may be provided on the hub. In both cases, it is possible to manufacture one impeller from the two elements. Further, since it is possible to carve the blades by machining, it is possible to accurately form the passage, compared to castings. Specifically, the method of manufacturing the impeller includes: a step of forming a hub that is provided with a plurality of blades; a step of disposing a core on the hub such that the core is interposed between the blades; a step of disposing a cover on the blades, the cover being a plate on which grooves conforming to shapes of the blades are formed; and a step of welding the cover and the blades. Further, through-holes conforming to the shapes of the blades are provided on the core, such that the blades are fitted in the core when the core is disposed.

    <Second Embodiment>



    [0076] In the first embodiment, the core is a single large core having a disk shape, and has nearly the same size as the hub of the impeller. The core has resistance to compression, but is fragile. A corner portion easily chips, or a thin outer circumference portion easily collapses by its own weight. After the molding of the core, the hardening treatment needs to be performed, and on this occasion, a deformation such as a warp easily occurs. Particularly, in the case of a single large core having a disk shape, the deformation is large. As a result, it is difficult to mount the core to the impeller, and the core is easily damaged by forcibly mounting the core.

    [0077] In the case where the impeller is manufactured using a large disk core as in the case of the first embodiment, the disk core becomes unusable if the disk core has a partial defect. Although primary materials of the core are relatively inexpensive, the fabrication labor cost of the core is expensive. Therefore, if the disk core becomes unusable, a great influence is exerted on the cost. Further, in the core according to the first embodiment, for securing the ventilation of the back shield gas, a work for providing small vent holes is performed. Also at this time, the risk of the damage of the core is high, and therefore, the work requires carefulness and effort.

    [0078] On the other hand, in a second embodiment, instead of the disk core, there is used a divided core into which the disk core is divided along the shape of the blade. Here, a plurality of divided cores is used, and as an example, division angles around the central axis of the impeller are roughly the same. By using the divided cores into which the core is divided in this way, it is possible to reduce the weight of each of the divided cores, and to avoid the collapse of the divided core due to its own weight.

    [0079] Since the divided core has a small size, the deformation amount during the hardening treatment is also small, and combined with the division structure, the workability for mounting (assembling) the divided core to the impeller is very high. Even when the divided core becomes unusable due to deformation or damage, one of the divided cores only needs to be replaced because of the division structure, and therefore, the influence on fabrication cost is decreased. Further, as shown in Figure 14 described later, by providing an inner circumference spacer between the divided core and the divided core and providing a gap between the divided core and the divided core, it is possible to secure the ventilation of the back shield gas, and it is possible to avoid a vent hole making work by which the core is damaged at a high risk.

    [0080] Subsequently, a method of manufacturing an impeller will be described along a flowchart in Figure 19, with reference to Figure 12 to Figure 18. Figure 12 is a perspective view of a hub before and after a centering fixture is mounted. Figure 13 is a perspective view of the hub before and after divided cores are disposed. Figure 14 is a perspective view of one divided core as viewed from the back side. Figure 15 is an exploded perspective view of the divided cores as viewed from the back side, for describing inner circumference spacers and outer circumference spacers. Figure 16 is a perspective view of the hub when the inner circumference spacers, the outer circumference spacers and the divided cores are disposed. Figure 17 is a partial perspective view of the hub taken along a polyline L1 and a straight line L2 in Figure 16. In Figure 17, inner circumference spacers 34-1 to 34-13 and outer circumference spacers 35-1 to 35-13 are omitted. Figure 18 is a perspective view of the hub before and after a cover is disposed. Figure 19 is a flowchart showing an example of the method of manufacturing the impeller according to the second embodiment.

    [0081] In the following, the description will be made along the flowchart in Figure 19.

    [0082] (Step S101) First, a hub 31 provided with a plurality of blades 41-1 to 41-13 is formed. Specifically, the hub 31 is carved from a forging material by machining, and thereby, the blades 41-1 to 41-13 are integrally carved. As shown in Figure 12, the hub 31 has a disk shape, and a hollow space is formed at the center of the hub 31. The plurality of blades 41-1 to 41-13 are provided from the center of the hub 31 at an equal angular interval, and the shapes of the blades 41-1 to 41-13 are roughly the same as each other.

    [0083] (Step S102) Next, as shown in Figure 12, a centering fixture 32 is mounted in the hollow space formed in the hub 31.

    [0084] (Step S103) Next, divided cores 33-1 to 33-13, inner circumference spacers 34-1 to 34-13 and outer circumference spacers 35-1 to 35-13 are disposed. Specifically, as shown in Figure 13, the plurality of divided cores 33-1 to 33-13 is disposed on the hub 31, such that each of the divided cores 33-1 to 33-13 is disposed at each interspace of adjacent blades. As shown in Figure 13 and Figure 17, the divided cores 33-1 to 33-13 protrude to the inner circumference side than from the hub 31.

    [0085] In the divided core 33-1, the shapes of the divided cores are roughly the same as each other, and the shape of each divided core has a shape shown in Figure 14. By this configuration, as a wooden pattern for molding the divided cores 33-1 to 33-13, only a single set having a small size is needed, and the divided cores 33-1 to 33-13 can be formed with the same wooden pattern. Further, since the wooden pattern for molding the divided cores 33-1 to 33-13 has a small size, it is possible to use a small and inexpensive additive manufacturing device for resin shaping, in the fabrication of the wooded pattern, and it is possible to fabricate a wooden pattern (resin pattern) having a relatively high shape accuracy at low cost in a short time. Therefore, it is possible to make the divided cores 33-1 to 33-13 at low cost in a short time. Alternatively, with the additive manufacturing device, it is possible to mass-produce the same divided cores, based on the same 3D model.

    [0086] As shown in Figure 15 and Figure 16, in the step of disposing the divided cores 33-1 to 33-13, the inner circumference spacers 34-1 to 34-13 are provided at interspaces of adjacent divided cores 33-1 to 33-13, on the inner circumference side. By this configuration, it is possible to perform the positioning of the divided cores 33-1 to 33-13.

    [0087] As shown in Figure 16, the heights of the inner circumference spacers 34-1 to 34-13 when the inner circumference spacers 34-1 to 34-13 are provided are lower than the heights of the divided cores 33-1 to 33-13. In the step of the welding described later, the inert gas is supplied from the inner circumference side, such that the inert gas flows through a passage that is formed between the hub 31 and the cover 36. By this configuration, it is possible to provide a slight gap between a surface of the divided core and a surface of the divided core, and it is possible to supply the inert gas from the gap. Therefore, it is possible to avoid a vent hole formation work by which the core is damaged at a high risk.

    [0088] As shown in Figure 15 and Figure 16, in the step of disposing the divided cores 33-1 to 33-13, the outer circumference spacers 35-1 to 35-13 are respectively disposed at interspaces of adjacent blades 41-1 to 41-13 on the outer circumference sides of the divided cores 33-1 to 33-13.

    [0089]  As shown in Figure 17, in the step of disposing the divided cores, the divided cores are disposed such that the back surfaces of the inner circumference sides of the divided cores contact with the front surface of the centering fixture 32. By this configuration, the divided cores support the inner circumference side of the cover, and therefore, it is possible to avoid the inner circumference side of the cover provided on the cores from falling down due to the welding.

    [0090] As shown in Figure 17, the thicknesses of the divided cores 33-1 to 33-13 are smaller than the heights of the blades with respect to the front surface of the hub 31, by a predetermined length. The predetermined length is a length corresponding to decrease amount of the heights of the blades when the top surfaces of the blades melt by the welding and thereby the blades contract. Thereby, the top surfaces of the blades melt by the welding, and thereby, the blades contract so that the heights become roughly the same as the thicknesses of the divided cores 33-1 to 33-13. Therefore, it is possible to prevent unnecessary force from being applied to the divided cores 33-1 to 33-13.

    [0091] Further, the divided cores 33-1 to 33-13 need to be removed after the welding, and therefore, it is preferable that the divided cores 33-1 to 33-13 be made of a raw material that can be physically broken readily. In the embodiment, as an example, the divided cores 33-1 to 33-13 are formed using a material described in Patent Literature 1. By using such a material, the physical removal of the divided cores 33-1 to 33-13 becomes easy.

    [0092] (Step S104) Next, as shown in Figure 18, the cover 36 on which grooves 37-1 to 37-13 conforming to the shapes of the blades 41-1 to 41-13 are formed is disposed on the hub 31 and the divided cores 33-1 to 33-13.

    [0093] (Step S105) Next, the cover 36 and the blades 41-1 to 41-13 are welded, while the inert gas is supplied from the inner circumference side. In this way, in the step of the welding, the inert gas is supplied from the inner circumference side, such that the inert gas flows through the passage that is formed between the hub 31 and the cover 36. Thereby, the presence of the outer circumference spacers 35-1 to 35-13 can restrain the inert gas from leaking to the outside. It is possible to make the inert gas reach a penetration bead that is generated at the time of the welding of the blades, and it is possible to avoid the penetration bead from being oxidized.

    [0094] (Step S106) Next, a heat treatment is performed. For example, the temperature is slowly increased, and then is slowly decreased. Thereby, it is possible to let out residual stress.

    [0095] (Step S107) Next, an outer circumference portion is carved. Thereby, the outer circumference spacers 35-1 to 35-13 are removed.

    [0096] (Step S108) Next, the divided cores 33-1 to 33-13 are physically broken by a steel wire or the like.

    [0097] (Step S109) Next, the impeller is finished into a desired shape by machining. Thereby, the impeller is completed.

    [0098] Thus, the method of manufacturing the impeller according to the second embodiment includes: the step of forming the hub 31 that is provided with the plurality of blades 41-1 to 41-13; the step of disposing the plurality of divided cores 33-1 to 33-13 on the hub 31, such that the divided cores are respectively disposed at the interspaces of adjacent blades; the step of disposing the cover 36 on the hub 31 and the divided cores 33-1 to 33-13; and the step of welding the cover 36 and the blades 41-1 to 41-13.

    [0099] In this configuration, by using the divided cores 33-1 to 33-13, each of the divided cores 33-1 to 33-13 has light, and it is possible to avoid the collapse due to its own weight. Further, it is possible to decrease the bending moment that is generated in the divided cores 33-1 to 33-13 when the divided cores 33-1 to 33-13 are held up, and to secure the strength allowing works such as the fabrication of the divided cores 33-1 to 33-13 and welding setup (the assembly of the divided core). Since each of the divided cores 33-1 to 33-13 has a small size, the deformation amount during the hardening treatment is also small, and combined with the division structure, it is possible to improve the workability for mounting (assembling) the divided cores to the impeller. Further, even when the divided cores 33-1 to 33-13 become unusable due to deformation or damage, one of the divided cores 33-1 to 33-13 only needs to be replaced because of the division structure, and therefore, the influence on fabrication cost is decreased.

    [0100] In the embodiment, the blades 41-1 to 41-13 are formed on the hub 31, but without being limited to this, the blades 41-1 to 41-13 may be formed on the cover 36. In that case, the method of manufacturing the impeller may include: a step of forming a cover that is provided with a plurality of blades; a step of disposing a plurality of divided cores on the cover, such that the divided cores are respectively disposed at interspaces of adjacent blades; a step of disposing a hub on the cover and the divided cores; and a step of welding the hub and the blades.

    Reference Signs List



    [0101] 1, 21: impeller, 2, 31: hub, 3, 36: cover, 4, 41-1 to 41-13: blade, 5, 37-1 to 37-13: groove, 7: fixture, 8, 32: centering fixture, 9: hole, 10: core, 11: welding portion for fixing, 12: welding portion, 14: through-hole, 15: vent hole, 16: tape, 17: inner circumference portion, 18: boss portion, 19: outer circumference portion, 33-1 to 33-13: divided core, 34-1 to 34-13: inner circumference spacer, 35-1 to 35-13: outer circumference spacer


    Claims

    1. A method of manufacturing an impeller (1), the method comprising:

    a step of forming a cover (3) that is provided with a plurality of blades (4);

    a step of disposing a core (10) on the cover (3) such that the core (10) is interposed between the blades (4) ;

    a step of disposing a hub (2) on the blades (4), the hub (2) being a plate on which grooves (5) conforming to shapes of the blades (4) are formed; and

    a step of welding the hub and the blades (4), wherein

    through-holes (14) conforming to the shapes of the blades (4) are provided on the core (10), such that the blades (4) are fitted in the core (10) when the core (10) is disposed,

    a vent hole (15) is provided on the core (10), and

    the method further comprises a step of affixing a tape (16) over a gap between the hub (2) and the core (10) and filling an inert gas from the vent hole (15) into a space among the hub (2), the cover (3) and the core (10), before the step of welding the hub (2) and the blades (4).


     
    2. The method of manufacturing the impeller (1) according to claim 1, the method further comprising a step of breaking and removing the core (10), when a temperature of the hub (2) becomes lower than a predetermined temperature after the step of welding the hub (2) and the blades (4).
     
    3. The method of manufacturing the impeller (1) according to claim 1 or 2, wherein
    the through-holes (14) of the core have shapes similar to the shapes of the blades (4), and are wider than the blades (4) in circumferential width.
     
    4. The method of manufacturing the impeller (1) according to any one of claims 1 to 3, wherein

    the number of the through-holes (15) provided on the core (10) is the same as the number of the blades (4), and

    in the step of disposing the core (10), the core (10) is disposed by overlaying the core (10) on the cover (3) such that horizontal positions of the plurality of blades (4) roughly coincide with horizontal positions of the corresponding through-holes (14).


     
    5. The method of manufacturing the impeller (1) according to any one of claims 1 to 4, wherein

    the cover (3) and the core (10) have disk shapes, and

    in the step of disposing the core (10) on the cover (3), the core (10) is disposed such that a central axis of the core (10) roughly coincides with a central axis of the cover (3).


     
    6. The method of manufacturing the impeller (1) according to any one of claims 1 to 5, wherein

    the hub (2) and the core (10) have disk shapes, and

    in the step of disposing the hub (2) on the blades (14), the hub (2) is disposed such that a central axis of the hub (2) roughly coincides with a central axis of the cover (3).


     
    7. The method of manufacturing the impeller (1) according to any one of claims 1 to 6, wherein
    the core (10) is formed using a raw material that is used in precision casting.
     
    8. The method of manufacturing the impeller (1) according to any one of claims 1 to 7, wherein
    the cover (3) is a cover (3) that is carved integrally with the blades (4) by machining.
     
    9. The method of manufacturing the impeller (1) according to any one of claims 1 to 8, wherein

    holes (9) for welding are provided in the grooves (5) of the hub (2), and

    in the step of welding the hub (2) and the blades (4), a welding material is poured through the holes (9) for welding, and the hub (2) and the blades (4) are welded.


     
    10. The method of manufacturing the impeller (1) according to any one of claims 1 to 9, wherein
    the impeller (1) is an impeller (1) of a rotating machine.
     
    11. A method of manufacturing an impeller (1), the method comprising:

    a step of forming a hub (2) that is provided with a plurality of blades (4);

    a step of disposing a core (10) on the hub (2) such that the core (10) is interposed between the blades (4);

    a step of disposing a cover (3) on the blades (4), the cover (3) being a plate on which grooves (5) conforming to shapes of the blades (4) are formed; and

    a step of welding the cover (3) and the blades (4), wherein

    through-holes (14) conforming to the shapes of the blades (4) are provided on the core (10), such that the blades (4) are fitted in the core (10) when the core (10) is disposed,

    a vent hole (15) is provided on the core (10), and

    the method further comprises a step of affixing a tape (16) over a gap between the hub (2) and the core (10) and filling an inert gas from the vent hole (15) into a space among the hub (2), the cover (3) and the core (10), before the step of welding the cover (3) and the blades (4).


     
    12. A method of manufacturing an impeller, the method comprising:

    a step of forming a hub (31) that is provided with a plurality of blades (41-1 to 41-13);

    a step of disposing a plurality of divided cores (33-1 to 33-13) on the hub (31), such that each of the divided cores (33-1 to 33-13) is disposed at each interspace of the adjacent blades (41-1 to 41-13);

    a step of disposing a cover (36) on the hub and the divided cores (33-1 to 33-13); and

    a step of welding the cover (36) and the blades (41-1 to 41-13), wherein

    a hollow space is formed at a center of the hub (31),

    the divided cores (33-1 to 33-13) protrude to an inner circumference side of the hub (31),

    the method comprises a step of providing inner circumference spacers (34-1 to 34-13) at interspaces of the adjacent divided cores (33-1 to 33-13) on the inner circumference side, in the step of disposing the divided cores (33-1 to 33-13),

    heights of the inner circumference spacers (34-1 to 34-13) when the inner circumference spacers (34-1 to 34-13) are provided are lower than heights of the divided cores (33-1 to 33-13), and

    in the step of welding the cover (36) and the blades (41-1 to 41-13), an inert gas is supplied from an inner circumference side, such that the inert gas flows through a passage that is formed between the hub (31) and the cover (36).


     
    13. The method of manufacturing the impeller according to claim 12, wherein

    the method further comprises a step of mounting a centering fixture (32) in the hollow space formed in the hub (31), after the step of forming the hub (31) and before the divided cores (33-1 to 33-13) are disposed, and

    in the step of disposing the divided cores (33-1 to 33-13), the divided cores (33-1 to 33-13) are disposed such that back surfaces of inner circumference sides of the divided cores contact with a front surface of the centering fixture (32).


     
    14. The method of manufacturing the impeller according to claim 12 or 13, the method further comprising a step of respectively disposing outer circumference spacers (35-1 to 35-13) at interspaces of the adjacent blades (41-1 to 41-13) on outer circumference sides of the divided cores (33-1 to 33-13), in the step of disposing the divided cores (33-1 to 33-13) .
     
    15. The method of manufacturing the impeller according to any one of claims 12 to 14, wherein

    the plurality of blades (41-1 to 41-13) are provided from a center of the hub (31) at an equal angular interval, and shapes of the blades (41-1 to 41-13) are roughly the same as each other, and

    shapes of the divided cores (33-1 to 33-13) are roughly the same as each other.


     
    16. The method of manufacturing the impeller according to any one of claims 12 to 15, wherein
    thicknesses of the divided cores (33-1 to 33-13) are smaller than heights of the blades (41-1 to 41-13) with respect to a front surface of the hub (31), by a predetermined length.
     
    17. A method of manufacturing an impeller, the method comprising:

    a step of forming a cover (36) that is provided with a plurality of blades (41-1 to 41-13);

    a step of disposing a plurality of divided cores (33-1 to 33-13) on the cover (36), such that each of the divided cores (33-1 to 33-13) are disposed at each interspace of the adjacent blades;

    a step of disposing a hub (31) on the cover and the divided cores (33-1 to 33-13) ; and

    a step of welding the hub (31) and the blades (41-1 to 41-13), wherein

    a hollow space is formed at a center of the hub (31),

    the divided cores (33-1 to 33-13) protrude to an inner circumference side of the hub (31),

    the method comprises a step of providing inner circumference spacers (34-1 to 34-13) at interspaces of the adjacent divided cores (33-1 to 33-13) on the inner circumference side, in the step of disposing the divided cores (33-1 to 33-13),

    heights of the inner circumference spacers (34-1 to 34-13) when the inner circumference spacers (34-1 to 34-13) are provided are lower than heights of the divided cores ( 33-1 to 33-13), and

    in the step of welding the hub (31) and the blades (41-1 to 41-13), an inert gas is supplied from an inner circumference side, such that the inert gas flows through a passage that is formed between the hub (31)and the cover (36).


     


    Ansprüche

    1. Verfahren zur Herstellung eines Laufrades (1), wobei das Verfahren Folgendes aufweist:

    einen Schritt des Formens einer Abdeckung (3), die mit einer Vielzahl von Schaufeln (4) versehen ist,

    einen Schritt des Anordnens eines Kerns (10) auf der Abdeckung (3), so dass der Kern (10) zwischen den Schaufeln (4) angeordnet ist;

    einen Schritt des Anordnens einer Nabe (2) auf den Schaufeln (4), wobei die Nabe (2) eine Platte ist, in der Nuten (5) geformt sind, die an die Formen der Schaufeln (4) angepasst sind; und

    einen Schritt des Schweißens der Nabe und der Schaufeln (4),

    wobei

    Durchgangslöcher (14), die an die Formen der Schaufeln (4) angepasst sind, an dem Kern (10) vorgesehen sind, so dass die Schaufeln (4) in den Kern (10) eingepasst werden, wenn der Kern (10) angeordnet wird,

    ein Entlüftungsloch (15) an dem Kern (10) vorgesehen ist und

    das Verfahren weiter einen Schritt des Befestigens eines Bandes (16) über einem Spalt zwischen der Nabe (2) und dem Kern (10) aufweist, und

    das Füllen eines inerten Gases von dem Entlüftungsloch (15) in den Raum unter der Nabe (2), der Abdeckung (3) und dem Kern (10) vor dem Schritt des Schweißens der Nabe (2) und der Schaufeln (4).


     
    2. Verfahren zur Herstellung des Laufrades (1) nach Anspruch 1, wobei das Verfahren weiter einen Schritt des Zerbrechens und Entfernens des Kerns (10) aufweist, wenn eine Temperatur der Nabe (2) nach dem Schritt des Schweißens der Nabe (2) und der Schaufeln (4) niedriger als eine vorbestimmte Temperatur wird.
     
    3. Verfahren zur Herstellung des Laufrades (1) nach Anspruch 1 oder 2, wobei
    die Durchgangslöcher (14) des Kerns Formen haben, die ähnlich den Formen der Schaufeln (4) sind, und wobei sie in Umfangsbreite breiter als die Schaufeln (4) sind.
     
    4. Verfahren zur Herstellung des Laufrades (1) nach einem der Ansprüche 1 bis 3, wobei
    die Anzahl der Durchgangslöcher (15), die in dem Kern (10) vorgesehen sind, die gleiche ist wie die Anzahl der Schaufeln (4) und wobei
    beim Schritt des Anordnens des Kerns (10) der Kern (10) durch Überlappen des Kerns (10) auf der Abdeckung (3) so angeordnet wird, dass horizontale Positionen der Vielzahl von Schaufeln (4) ungefähr mit horizontalen Positionen der entsprechenden Durchgangslöcher (14) zusammenfallen.
     
    5. Verfahren zur Herstellung des Laufrades (1) nach einem der Ansprüche 1 bis 4, wobei

    die Abdeckung (3) und der Kern (10) Scheibenformen haben, und

    beim Schritt des Anordnens des Kerns (10) auf der Abdeckung (3) der Kern (10) so angeordnet wird, dass eine Mittelachse des Kerns (10) ungefähr mit einer Mittelachse der Abdeckung (3) zusammenfällt.


     
    6. Verfahren zur Herstellung des Laufrades (1) nach einem der Ansprüche 1 bis 5, wobei

    die Nabe (2) und der Kern (10) Scheibenformen haben, und

    beim Schritt des Anordnens der Nabe (2) auf den Schaufeln (14) die Nabe (2) so angeordnet wird, dass eine Mittelachse der Nabe (2) ungefähr mit einer Mittelachse der Abdeckung (3) zusammenfällt.


     
    7. Verfahren zur Herstellung des Laufrades (1) nach einem der Ansprüche 1 bis 6, wobei
    der Kern (10) unter Verwendung eines Rohmaterials geformt wird, welches beim Präzisionsguss verwendet wird.
     
    8. Verfahren zur Herstellung des Laufrades (1) nach einem der Ansprüche 1 bis 7, wobei
    die Abdeckung (3) eine Abdeckung (3) ist, die integral mit den Schaufeln (4) durch maschinelle Bearbeitung herausgearbeitet ist.
     
    9. Verfahren zur Herstellung des Laufrades (1) nach einem der Ansprüche 1 bis 8, wobei

    Löcher (9) zum Schweißen in den Nuten (5) der Nabe (2) vorgesehen sind, und

    beim Schritt des Schweißens der Nabe (2) und der Schaufeln (4) ein Schweißmaterial durch die Löcher (9) zum Schweißen gegossen wird, und die Nabe (2) und die Schaufeln (4) geschweißt werden.


     
    10. Verfahren zur Herstellung des Laufrades (1) nach einem der Ansprüche 1 bis 9, wobei
    das Laufrad (1) ein Laufrad einer sich drehenden Maschine ist.
     
    11. Verfahren zur Herstellung eines Laufrades (1), wobei das Verfahren Folgendes aufweist:

    einen Schritt des Formens einer Nabe (2), die mit einer Vielzahl von Schaufeln (4) versehen ist;

    einen Schritt des Anordnens eines Kerns (10) auf der Nabe (2), so dass der Kern (10) zwischen den Schaufeln (4) angeordnet ist;

    einen Schritt des Anordnens einer Abdeckung (3) auf den Schaufeln (4),

    wobei die Abdeckung (3) eine Platte ist, in der Nuten (5) geformt sind, die an Formen der Schaufeln (4) angepasst sind; und

    einen Schritt des Schweißens der Abdeckung (3) und der Schaufeln (4),

    wobei Durchgangslöcher (14), die an die Formen der Schaufeln (4) angepasst sind, an dem Kern (10) vorgesehen sind, so dass die Schaufeln (4) in den Kern (10) eingepasst werden, wenn der Kern (10) angeordnet wird, wobei ein Entlüftungsloch (15) an dem Kern (10) vorgesehen ist, und

    wobei das Verfahren weiter einen Schritt des Befestigens eines Bandes (16) über einem Spalt zwischen der Nabe (2) und dem Kern (10) und des Füllens eines inerten Gases von dem Entlüftungsloch (15) in einen Raum unter der Nabe (2), der Abdeckung (3) und dem Kern (10) aufweist, und

    zwar vor dem Schritt des Schweißens der Abdeckung (3) und der Schaufeln (4).


     
    12. Verfahren zur Herstellung eines Laufrades (1), wobei das Verfahren Folgendes aufweist:

    einen Schritt des Formens einer Nabe (31), die mit einer Vielzahl von Schaufeln (41-1 bis 41-13) versehen ist;

    einen Schritt des Anordnens einer Vielzahl von geteilten Kernen (33-1 bis 33-13) auf der Nabe (31), so dass jeder der geteilten Kerne (33-1 bis 33-13) bei jedem Zwischenraum von den benachbarten Schaufeln (41-1 bis 41-13) angeordnet ist;

    einen Schritt des Anordnens einer Abdeckung (36) auf der Nabe und den geteilten Kernen (33-1 bis 33-13); und

    einen Schritt des Schweißens der Abdeckung (36) und der Schaufeln (41-1 bis 41-13), wobei

    ein hohler Raum in der Mitte der Nabe (31) geformt wird,

    die geteilten Kerne (33-1 bis 33-13) zu einer Innenumfangsseite der Nabe (31) vorstehen,

    das Verfahren einen Schritt aufweist, Innenumfangsabstandshalter (34-1 bis 34-13) an Zwischenräumen der benachbarten geteilten Kerne (33-1 bis 33-13) an der Innenumfangsseite vorzusehen, und zwar beim Schritt des Anordnens der geteilten Kerne (33-1 bis 33-13),

    Höhen der Innenumfangsabstandshalter (34-1 bis 34-13) niedriger sind als Höhen der geteilten Kerne (33-1 bis 33-13), wenn die Innenumfangsabstandshalter (34-1 bis 34-13) vorgesehen bzw. angeordnet werden, und

    beim Schritt des Schweißens der Abdeckung (36) und der Schaufeln (41-1 bis 41-13) ein inertes Gas von einer Innenumfangsseite so geliefert wird,

    dass das inerte Gas durch einen Durchlass fließt, der zwischen der Nabe (31) und der Abdeckung (36) geformt ist.


     
    13. Verfahren zur Herstellung der Laufrades nach Anspruch 12, wobei

    das Verfahren weiter einen Schritt des Montierens einer Zentrierungshalterung (32) in dem hohlen Raum aufweist, der in der Nabe (31) geformt ist,

    und zwar nach dem Schritt des Formens der Nabe (31) und bevor die geteilten Kerne (33-1 bis 33-13) angeordnet werden, und

    bei dem Schritt des Anordnens der geteilten Kerne (33-1 bis 33-13) die geteilten Kerne (33-1 bis 33-13) so angeordnet werden, dass Hinterseiten der Innenumfangseiten der geteilten Kerne mit einer Vorderseite der Zentrierungshalterung (32) in Kontakt sind.


     
    14. Verfahren zur Herstellung des Laufrades nach Anspruch 12 oder 13, wobei das Verfahren weiter einen Schritt aufweist, jeweils Außenumfangsabstandshalter (35-1 bis 35-13) bei Zwischenräumen der benachbarten Schaufeln (41-1 bis 41-13) an Außenumfangsseiten der geteilten Kerne (33-1 bis 33-13) anzuordnen, und zwar beim Schritt des Anordnens der geteilten Kerne (33-1 bis 33-13).
     
    15. Verfahren zur Herstellung des Laufrades nach einem der Ansprüche 12 bis 14, wobei
    die Vielzahl von Schaufeln (41-1 bis 41-13) von einer Mitte der Nabe (31) in einem gleichen Winkelintervall vorgesehen ist bzw. sind, und wobei Formen der Schaufeln (41-1 bis 41-13) ungefähr gleich zueinander sind, und wobei
    Formen der geteilten Kerne (33-1 bis 33-13) ungefähr gleich zueinander sind.
     
    16. Verfahren zur Herstellung des Laufrades nach einem der Ansprüche 12 bis 15, wobei
    Dicken der geteilten Kerne (33-1 bis 33-13) kleiner sind als Höhen der Schaufeln (41-1 bis 41-13) bezüglich einer Vorderseite der Nabe (31), und zwar um eine vorbestimmte Länge.
     
    17. Verfahren zur Herstellung eines Laufrades, wobei das Verfahren Folgendes aufweist:

    einen Schritt des Formens einer Abdeckung (36), die mit einer Vielzahl von Schaufeln (41-1 bis 41-13) versehen ist;

    einen Schritt des Anordnens einer Vielzahl von geteilten Kernen (33-1 bis 33-13) auf der Abdeckung (36), so dass jeder der geteilten Kerne (33-1 bis 33-13) jeweils bei einem Zwischenraum der benachbarten Schaufeln angeordnet ist;

    einen Schritt des Anordnens einer Nabe (31) auf der Abdeckung und den geteilten Kernen (33-1 bis 33-13); und

    einen Schritt des Schweißens der Nabe (31) und der Schaufeln (41-1 bis 41-13), wobei ein hohler Raum in einer Mitte der Nabe (31) geformt wird, wobei die geteilten Kerne (33-1 bis 33-13) zu einer Innenumfangsseite der Nabe (31) vorstehen,

    wobei das Verfahren einen Schritt des Vorsehens von Innenumfangsabstandshaltern (34-1 bis 34-13) bei Zwischenräumen von benachbarten geteilten Kernen (33-1 bis 33-13) an der Innenumfangsseite aufweist, und zwar beim Schritt des Anordnens der geteilten Kerne (33-1 bis 33-13),

    wobei Höhen der Innenumfangsabstandshalter (34-1 bis 34-13) niedriger sind als Höhen der geteilten Kerne (33-1 bis 33-13), wenn die Innenumfangsabstandshalter (34-1 bis 34-13) vorgesehen bzw. angeordnet werden, und wobei
    beim Schritt des Schweißens der Nabe (31) und der Schaufeln (41-1 bis 41-13) ein inertes Gas von einer Innenumfangsseite so geliefert wird, dass das inerte Gas durch einen Durchlass fließt, der zwischen der Nabe (31) und der Abdeckung (36) geformt ist.


     


    Revendications

    1. Procédé de fabrication d'une turbine (1), le procédé comprenant :

    une étape de formation d'un capot (3) qui est muni d'une pluralité de pales (4) ;

    une étape de disposition d'un cœur (10) sur le capot (3) de sorte que le cœur (10) soit interposé entre les pales (4) ;

    une étape de disposition d'un moyeu (2) sur les pales (4), le moyeu (2) étant une plaque sur laquelle sont formées des rainures (5) se conformant aux formes des pales (4) ; et

    une étape de soudage du moyeu et des pales (4), dans lequel

    des trous traversants (14) se conformant aux formes des pales (4) sont prévus sur le cœur (10), de sorte que les pales (4) sont ajustées dans le cœur (10) lorsque le cœur (10) est disposé,

    un évent (15) est prévu sur le cœur (10), et

    le procédé comprend en outre une étape d'apposition d'une bande (16) sur un espace entre le moyeu (2) et le cœur (10) et le remplissage d'un gaz inerte à partir de l'évent (15) dans un espace entre le moyeu (2), le capot (3) et le cœur (10), avant l'étape de soudage du moyeu (2) et des pales (4).


     
    2. Procédé de fabrication de la turbine (1) selon la revendication 1, le procédé comprenant en outre une étape de rupture et de retrait du cœur (10), lorsqu'une température du moyeu (2) devient inférieure à une température prédéterminée après l'étape de soudage du moyeu (2) et des pales (4).
     
    3. Procédé de fabrication de la turbine (1) selon la revendication 1 ou 2, dans lequel
    les trous traversants (14) du cœur ont des formes similaires aux formes des pales (4), et sont plus larges que les pales (4) en largeur circonférentielle.
     
    4. Procédé de fabrication de la turbine (1) selon l'une quelconque des revendications 1 à 3, dans lequel

    le nombre de trous traversants (15) prévus sur le cœur (10) est le même que le nombre de pales (4), et

    pendant l'étape de disposition du cœur (10), le cœur (10) est disposé en superposant le cœur (10) sur le capot (3) de sorte que des positions horizontales de la pluralité de pales (4) coïncident approximativement avec des positions horizontales des trous traversants correspondants (14).


     
    5. Procédé de fabrication de la turbine (1) selon l'une quelconque des revendications 1 à 4, dans lequel

    le capot (3) et le cœur (10) ont des formes de disques, et

    pendant l'étape de disposition du cœur (10) sur le capot (3), le cœur (10) est disposé de sorte qu'un axe central du cœur (10) coïncide approximativement avec un axe central du capot (3).


     
    6. Procédé de fabrication de la turbine (1) selon l'une quelconque des revendications 1 à 5, dans lequel

    le moyeu (2) et le cœur (10) ont des formes de disque, et

    pendant l'étape de disposition du moyeu (2) sur les pales (14), le moyeu (2) est disposé de sorte qu'un axe central du moyeu (2) coïncide approximativement avec un axe central du capot (3).


     
    7. Procédé de fabrication de la turbine (1) selon l'une quelconque des revendications 1 à 6, dans lequel
    le cœur (10) est formé en utilisant une matière première qui est utilisée dans un moulage de précision.
     
    8. Procédé de fabrication de la turbine (1) selon l'une quelconque des revendications 1 à 7, dans lequel
    le capot (3) est un capot (3) qui est taillé d'un seul tenant avec les pales (4) par usinage.
     
    9. Procédé de fabrication de la turbine (1) selon l'une quelconque des revendications 1 à 8, dans lequel

    des trous (9) pour le soudage sont prévus dans les rainures (5) du moyeu (2), et

    pendant l'étape de soudage du moyeu (2) et des pales (4), un matériau de soudage est versé à travers les trous (9) pour le soudage, et le moyeu (2) et les pales (4) sont soudés.


     
    10. Procédé de fabrication de la turbine (1) selon l'une quelconque des revendications 1 à 9, dans lequel
    la turbine (1) est une turbine (1) d'une machine tournante.
     
    11. Procédé de fabrication d'une turbine (1), le procédé comprenant :

    une étape de formation d'un moyeu (2) qui est muni d'une pluralité de pales (4) ;

    une étape de disposition d'un cœur (10) sur le moyeu (2) de sorte que le cœur (10) soit interposé entre les pales (4) ;

    une étape de disposition d'un capot (3) sur les pales (4), le capot (3) étant une plaque sur laquelle sont formées des rainures (5) se conformant aux formes des pales (4) ; et

    une étape de soudage du capot (3) et des pales (4), dans lequel

    des trous traversants (14) se conformant aux formes des pales (4) sont prévus sur le cœur (10), de sorte que les pales (4) sont ajustées dans le cœur (10) lorsque le cœur (10) est disposé,

    un évent (15) est prévu sur le cœur (10), et

    le procédé comprend en outre une étape d'apposition d'une bande (16) sur un espace entre le moyeu (2) et le cœur (10) et le remplissage d'un gaz inerte à partir de l'évent (15) dans un espace entre le moyeu (2), le capot (3) et le cœur (10), avant l'étape de soudage du capot (3) et des pales (4).


     
    12. Procédé de fabrication d'une turbine, le procédé comprenant :

    une étape de formation d'un moyeu (31) qui est muni d'une pluralité de pales (41-1 à 41-13) ;

    une étape de disposition d'une pluralité de cœurs divisés (33-1 à 33-13) sur le moyeu (31), de sorte que chacun des cœurs divisés (33-1 à 33-13) soit disposé au niveau de chaque espace intermédiaire des pales adjacentes (41-1 à 41-13) ;

    une étape de disposition d'un capot (36) sur le moyeu et sur les cœurs divisés (33-1 à 33-13) ; et

    une étape de soudage du capot (36) et des pales (41-1 à 41-13), dans lequel

    un espace creux est formé au niveau d'un centre du moyeu (31),

    les cœurs divisés (33-1 à 33-13) saillent d'un côté de la circonférence intérieure du moyeu (31), et

    le procédé comprend une étape de fourniture d'entretoises de circonférence intérieure (34-1 à 34-13) au niveau des espaces intermédiaires des cœurs divisés adjacents (33-1 à 33-13) sur le côté de la circonférence intérieure, pendant l'étape de disposition des cœurs divisés (33-1 à 33-13),

    des hauteurs des entretoises de circonférence intérieure (34-1 à 34-13) lorsque les entretoises de circonférence intérieure (34-1 à 34-13) sont prévues sont inférieures aux hauteurs des cœurs divisés (33-1 à 33-13), et,

    pendant l'étape de soudage du capot (36) et des pales (41-1 à 41-13), un gaz inerte est fourni depuis un côté de la circonférence intérieure, de sorte que le gaz inerte s'écoule à travers un passage qui est formé entre le moyeu (31) et le capot (36) .


     
    13. Procédé de fabrication de la turbine selon la revendication 12, dans lequel

    le procédé comprend en outre une étape de montage d'un dispositif de centrage (32) dans l'espace creux formé dans le moyeu (31), après l'étape de formation du moyeu (31) et avant que les cœurs divisés (33-1 à 33-13) ne soient disposés, et

    pendant l'étape de disposition des cœurs divisés (33-1 à 33-13), les cœurs divisés (33-1 à 33-13) sont disposés de sorte que des surfaces arrière de côtés de circonférence intérieure des coeurs divisés contactent une surface avant du dispositif de centrage (32) .


     
    14. Procédé de fabrication de la turbine selon la revendication 12 ou 13, le procédé comprenant en outre une étape de disposition respective d'entretoises de circonférence extérieure (35-1 à 35-13) au niveau d'espaces intermédiaires des pales adjacentes (41-1 à 41-13) sur des côtés de circonférence extérieure des cœurs divisés (33-1 à 33-13), pendant l'étape de disposition des cœurs divisés (33-1 à 33-13).
     
    15. Procédé de fabrication de la turbine selon l'une quelconque des revendications 12 à 14, dans lequel

    la pluralité de pales (41-1 à 41-13) est prévue à partir d'un centre du moyeu (31) à un intervalle angulaire égal, et des formes des pales (41-1 à 41-13) sont approximativement identiques les unes aux autres, et

    des formes des cœurs divisés (33-1 à 33-13) sont approximativement identiques les unes aux autres.


     
    16. Procédé de fabrication de la turbine selon l'une quelconque des revendications 12 à 15, dans lequel
    des épaisseurs des cœurs divisés (33-1 à 33-13) sont inférieures aux hauteurs des pales (41-1 à 41-13) par rapport à une surface avant du moyeu (31), d'une longueur prédéterminée.
     
    17. Procédé de fabrication d'une turbine, le procédé comprenant :

    une étape de formation d'un capot (36) qui est muni d'une pluralité de pales (41-1 à 41-13) ;

    une étape de disposition d'une pluralité de cœurs divisés (33-1 à 33-13) sur le capot (36), de sorte que chacun des cœurs divisés (33-1 à 33-13) soit disposé au niveau de chaque espace intermédiaire des pales adjacentes ;

    une étape de disposition d'un moyeu (31) sur le capot et sur les cœurs divisés (33-1 à 33-13) ; et

    une étape de soudage du moyeu (13) et des pales (41-1 à 41-13), dans lequel

    un espace creux est formé au niveau d'un centre du moyeu (31),

    les cœurs divisés (33-1 à 33-13) saillent d'un côté de la circonférence intérieure du moyeu (31),

    le procédé comprend une étape de fourniture d'entretoises de circonférence intérieure (34-1 à 34-13) au niveau d'espaces intermédiaires des cœurs divisés adjacents (33-1 à 33-13) sur le côté de la circonférence intérieure, pendant l'étape de disposition des cœurs divisés (33-1 à 33-13),

    des hauteurs des entretoises de la circonférence intérieure (34-1 à 34-13) lorsque les entretoises de la circonférence intérieure (34-1 à 34-13) sont prévues sont inférieures aux hauteurs des cœurs divisés (33-1 à 33-13), et,

    pendant l'étape de soudage du moyeu (31) et des pales (41-1 à 41-13), un gaz inerte est fourni depuis un côté de la circonférence intérieure, de sorte que le gaz inerte s'écoule à travers un passage qui est formé entre le moyeu (31) et le capot (36) .


     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description