JPWO2020203868A1 - Turbine wheel and its manufacturing method - Google Patents

Abstract

The turbine wheel (10) for the supercharger is provided around a shaft body (12) formed of a Ni alloy and a shaft body (12), and is formed of a columnar crystal or a single crystal of the Ni alloy. It includes a plurality of blades (14) in which the crystal growth direction and the centrifugal force direction are the same direction.

Description

The present disclosure relates to a turbine wheel and a method for manufacturing the same, and more particularly to a turbine wheel for a turbocharger and a method for manufacturing the same.

The turbocharger is equipped with a turbine wheel and a compressor impeller. The turbine wheel and the compressor impeller are connected by a rotor shaft. Turbine wheels are exposed to hot combustion gases. Therefore, the turbine wheel for the turbocharger is cast of Ni alloy (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2004-107724

By the way, a turbine wheel for a turbocharger is configured by providing a plurality of blades around a central axis. Turbine wheels are usually manufactured by casting multiple blades with a Ni alloy integrally with the central shaft. From this, the blade is formed of a metal structure composed of equiaxed crystals of Ni alloy. When the metallographic structure of the blade is made of equiaxed crystals, the mechanical strength such as high temperature creep strength is lowered with respect to the centrifugal force direction of the blade, and the heat resistance of the turbine wheel may be lowered.

Therefore, an object of the present disclosure is to provide a turbine wheel capable of improving heat resistance and a method for manufacturing the same.

The turbine wheel according to the present disclosure is a turbine wheel for a supercharger, and is provided with a shaft body formed of a Ni alloy and a shaft body provided around the shaft body, and is formed of a columnar crystal or a single crystal of the Ni alloy. It is provided with a plurality of blades in which the crystal growth direction and the centrifugal force direction are the same.

In the turbine wheel according to the present disclosure, the shaft body may be formed of equiaxed crystals.

The method for manufacturing a turbine wheel according to the present disclosure is a method for manufacturing a turbine wheel for a supercharger, in which a shaft body is cast with a Ni alloy and a plurality of blade bodies are unidirectionally solidified cast or a single crystal cast with a Ni alloy. A casting step is provided, and an assembly step of assembling the plurality of blades around the shaft body so that the crystal growth direction and the centrifugal force direction are in the same direction is provided.

In the method for manufacturing a turbine wheel according to the present disclosure, in the casting process, the plurality of blades are cast with a single blade for each blade, and in the assembly process, the plurality of blades are formed around the shaft. May be joined to.

In the method for manufacturing a turbine wheel according to the present disclosure, in the assembly step, a fitting groove into which the blade body can be fitted is formed around the shaft body along the axial direction, and the blade body is fitted into the fitting groove. It may be fitted to and joined.

In the method for manufacturing a turbine wheel according to the present disclosure, in the casting step, a plurality of single units in which one of the plurality of blade bodies and one of a plurality of divided shaft bodies obtained by dividing the shaft body in the axial direction are integrated. The wing structure is cast with Ni alloy, and the wing body of the single wing structure is unidirectionally solidified or single crystal cast. After laminating, the divided shafts of the plurality of single-wing structures may be integrally joined to each other.

In the method for manufacturing a turbine wheel according to the present disclosure, in the assembly step, a pin hole penetrating in the axial direction is formed in the split shaft body of the single blade structure, and the split shaft body of the plurality of single blade structures is used as an axis. After stacking in the direction, a pin formed of Ni alloy may be inserted into the pin hole to join the divided shafts of the plurality of single-blade structures integrally with the pin.

In the method for manufacturing a turbine wheel according to the present disclosure, in the casting step, two blade bodies facing the shaft body in the plurality of blade bodies and a plurality of divided shaft bodies obtained by dividing the shaft body in the axial direction are used. A plurality of two-blade structures in which one of the above is integrated is cast with a Ni alloy, and the two blades of the two-blade structure are unidirectionally solidified or single-crystal cast. After stacking the split shafts of the plurality of two-blade structures in the axial direction, the split shafts of the plurality of two-blade structures may be integrally joined to each other.

In the method for manufacturing a turbine wheel according to the present disclosure, in the assembly step, a pin hole is formed in the split shaft of the two-blade structure so as to penetrate in the axial direction, and the split shaft of the plurality of two-blade structures is formed. A pin formed of a Ni alloy may be inserted into the pin hole after laminating the two blades in the axial direction, and the split shafts of the plurality of two-blade structures may be integrally joined to the pin.

According to the turbine wheel having the above configuration and the manufacturing method thereof, the heat resistance of the turbine wheel can be improved.

It is a schematic diagram which shows the structure of the turbine wheel in the 1st Embodiment of this disclosure. It is sectional drawing which shows the structure of the turbine wheel in 1st Embodiment of this disclosure. It is a flowchart which shows the structure of the manufacturing method of the turbine wheel in the 1st Embodiment of this disclosure. It is a schematic diagram for demonstrating the manufacturing method of the turbine wheel in the 1st Embodiment of this disclosure. It is sectional drawing which shows the structure of the supercharger in 1st Embodiment of this disclosure. It is a schematic diagram for demonstrating the manufacturing method of the turbine wheel in the 2nd Embodiment of this disclosure. It is a schematic diagram for demonstrating the manufacturing method of the turbine wheel in the 3rd Embodiment of this disclosure. FIG. 3 is a schematic cross-sectional view showing the structure of a mold for casting a single-blade structure in the third embodiment of the present disclosure. It is a schematic diagram for demonstrating the manufacturing method of the turbine wheel in the 4th Embodiment of this disclosure. It is a schematic diagram for demonstrating the manufacturing method of the turbine wheel in the 5th Embodiment of this disclosure. In the fifth embodiment of the present disclosure, it is sectional drawing which shows the structure of the mold which casts a two-blade structure. It is a schematic diagram for demonstrating the manufacturing method of the turbine wheel in the 6th Embodiment of this disclosure.

[First Embodiment]
Hereinafter, the first embodiment of the present disclosure will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing the configuration of the turbine wheel 10. FIG. 2 is a schematic cross-sectional view showing the configuration of the turbine wheel 10. The turbine wheel 10 is used for a supercharger for vehicles, ships, and the like. The turbine wheel 10 includes a shaft body 12 and a plurality of blade bodies 14 provided around the shaft body 12.

The shaft body 12 is provided at the center of the turbine wheel 10 and has a function as a central shaft. The shaft body 12 is made of a cast product of Ni alloy. The shaft body 12 can be formed of a columnar crystal, a single crystal, or an equiaxed crystal of a Ni alloy. The shaft body 12 is preferably formed of equiaxed crystals. Fatigue strength and the like can be increased by forming the shaft body 12 with equiaxed crystals.

The plurality of blade bodies 14 are provided around the shaft body 12. The blade body 14 is made of a cast product of Ni alloy. An even number of blades 14 may be provided around the shaft body 12, or an odd number of blades 14 may be provided. When an odd number of blades 14 are provided around the shaft body 12, resonance of the turbine wheel 10 and the like can be suppressed. The blade bodies 14 may be provided around the shaft body 12 at equal intervals. In FIG. 1, the number of blades 14 is eight, but the number of blades 14 is not particularly limited as long as it is two or more.

The wing body 14 is formed of columnar crystals or single crystals of Ni alloy, and the crystal growth direction and the centrifugal force direction are formed in the same direction. As a result, when the turbine wheel 10 rotates, the direction of the centrifugal force applied to the blade 14 is the same as the crystal growth direction, so that the creep strength and the like can be increased. In FIG. 2, the crystal growth direction in the blade body is indicated by an arrow. Columnar crystals or single crystals are formed in a unidirectional crystal growth direction. Columnar crystals or single crystals exhibit the highest mechanical strength in the crystal growth direction. Therefore, by setting the crystal growth direction and the centrifugal force direction to the same direction, the mechanical strength of the blade body 14 can be increased. The crystal growth direction of the Ni alloy is the [001] direction of the Miller index.

The Ni alloy for casting the shaft body 12 and the blade body 14 is not particularly limited, but it is preferable to use a Ni alloy having heat resistance. MarM247, Rene'N4, CMSX-2 and the like can be applied to the Ni alloy. The shaft body 12 and the blade body 14 may be formed of the same Ni alloy or different Ni alloys, but may be formed of the same Ni alloy.

Next, a method of manufacturing the turbine wheel 10 will be described. FIG. 3 is a flowchart showing the configuration of a manufacturing method of the turbine wheel 10. The method for manufacturing the turbine wheel 10 includes a casting step (S10) and an assembly step (S12). FIG. 4 is a schematic diagram for explaining a method for manufacturing the turbine wheel 10.

The casting step (S10) is a step of casting the shaft body 12 with a Ni alloy and unidirectional solidifying casting or single crystal casting of a plurality of blade bodies 14 with a Ni alloy.

The shaft body 12 may be formed by unidirectional solidification casting or single crystal casting of a Ni alloy, or may be formed by ordinary casting of a Ni alloy. When the shaft body 12 is solidified and cast in one direction, the metal structure of the shaft body 12 is formed of columnar crystals. When the shaft body 12 is cast as a single crystal, the metal structure of the shaft body 12 is formed of a single crystal. When the shaft body 12 is normally cast, the metal structure of the shaft body 12 is formed by equiaxed crystals. The shaft body 12 is cast separately from the plurality of blade bodies 14.

The plurality of blades 14 are formed by unidirectional solidification casting or single crystal casting of a Ni alloy. The plurality of blade bodies 14 are cast as a single blade for each blade body. When the blade body 14 is solidified and cast in one direction, the metal structure of the blade body 14 is formed by columnar crystals. When the blade body 14 is cast as a single crystal, the metal structure of the blade body 14 is formed of a single crystal. In FIG. 4, the crystal growth direction in the blade body 14 is indicated by an arrow.

As a method for casting the shaft body 12 and the blade body 14, a general one-way solidification casting method, a single crystal casting method, or an ordinary casting method of Ni alloy can be used. A precision casting method or the like may be used as the casting method for the shaft body 12 and the blade body 14.

The assembly step (S12) is a step of assembling the plurality of blades 14 around the shaft body 12 so that the crystal growth direction and the centrifugal force direction are in the same direction. The plurality of blades 14 are assembled by joining around the shaft body 12 so that the crystal growth direction is the same as the centrifugal force direction. The plurality of blades 14 are joined so that the blades do not interfere with each other. The joining method is not particularly limited, but a general Ni alloy joining method can be applied. The joining method can be, for example, welding, diffusion welding, friction welding or the like. Further, when joining the plurality of blades 14 around the shaft body 12, an inlay or the like may be provided for positioning or the like. In this way, the turbine wheel 10 can be manufactured.

The turbine wheel 10 can be used for a supercharger for a vehicle, a ship, or the like. FIG. 5 is a schematic cross-sectional view showing the configuration of the turbocharger 20. The turbocharger 20 includes a turbine wheel 10 and a compressor impeller 22. The turbine wheel 10 and the compressor impeller 22 are connected by a rotor shaft 24. Since the blade body 14 of the turbine wheel 10 has the same direction as the crystal growth direction and the centrifugal force direction, the creep strength and the like are enhanced. As a result, the heat resistance of the turbine wheel 10 is improved, so that the rotation speed can be increased or the combustion temperature can be made higher to improve the performance of the turbocharger 20.

As described above, according to the above configuration, the crystal growth direction of the wing body is the same as the centrifugal force direction, so that the creep strength of the wing body and the like can be increased. This makes it possible to improve the heat resistance of the turbine wheel.

[Second Embodiment]
The second embodiment of the present disclosure will be described in detail below with reference to the drawings. The same components as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. The second embodiment is different from the first embodiment in the method of manufacturing the turbine wheel.

In the second embodiment, in the assembly process, a fitting groove into which the blade body can be fitted is formed around the shaft body along the axial direction, and the blade body is fitted into the fitting groove and joined. Since the casting process of the second embodiment is the same as the casting process of the first embodiment, detailed description thereof will be omitted.

Next, the method for manufacturing the turbine wheel in the second embodiment will be described in more detail. FIG. 6 is a schematic diagram for explaining a method for manufacturing a turbine wheel. The arrow in FIG. 6 indicates the crystal growth direction in the blade body 14. The shaft body 30 has a fitting groove 32 into which the blade body 14 can be fitted. The fitting groove 32 is formed so that the side edge of the blade body 14 can be fitted. The fitting groove 32 is formed on the outer peripheral surface of the shaft body 30 along the axial direction. The shaft body 30 may be formed by casting the shaft body 12 of the first embodiment and then machining the fitting groove 32 or the like. The plurality of blades 14 are cast by the same casting method as in the first embodiment.

Next, the plurality of blades 14 are fitted and attached to the fitting grooves 32 of the shaft body 30. Since the blade body 14 may be fitted and mounted in the fitting groove 32 of the shaft body 30, the positioning accuracy of the blade body 14 is improved. Further, since the blade body 14 may be fitted and attached to the fitting groove 32 of the shaft body 30, the joining between the blade body 14 and the shaft body 30 becomes easy. The joining method can be, for example, welding, diffusion welding, friction welding or the like.

According to the above configuration, the effect of the first embodiment is obtained, and a fitting groove into which the blade body can be fitted is formed around the shaft body along the axial direction, and the blade body is fitted into the fitting groove. Since the blades are joined together, the positioning accuracy of the blades is improved, and the joints between the blades and the shafts are facilitated. This can improve the productivity of the turbine wheel.

[Third Embodiment]
Hereinafter, the third embodiment of the present disclosure will be described in detail with reference to the drawings. The same components as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. The third embodiment is different from the first embodiment in the method of manufacturing the turbine wheel.

In the casting process, a plurality of single-blade structures in which one of the plurality of blades and one of the plurality of split shafts obtained by dividing the shaft in the axial direction are integrally cast with Ni alloy, and the single-blade structure is formed. One-way solidification casting or single crystal casting of the wing body of the body. In the assembling step, after laminating the divided shafts of a plurality of single-wing structures in the axial direction, the divided shafts of the plurality of single-wing structures are integrally joined and assembled.

Next, the method for manufacturing the turbine wheel according to the third embodiment will be described in more detail. FIG. 7 is a schematic diagram for explaining a method for manufacturing a turbine wheel. The arrow in FIG. 7 indicates the crystal growth direction of the blade body 14. In FIG. 7, the turbine wheel is formed by assembling, for example, eight single-blade structures 42, 46, 48-58. The shaft body is divided into eight divided shaft bodies in the axial direction. In the single blade structure 42, the blade body 14 and the split shaft body 44 are integrally cast. The split shaft body 44 is provided on the upper end side of the blade body 14. In the single blade structure 46, the blade body 14 and the split shaft body 47 are integrally cast. The split shaft body 47 is provided on the lower end side of the blade body 14. The single-wing structures 48 to 58 are also cast in the same manner as the single-wing structures 42 and 46. In the single wing structures 48 to 58, each split shaft corresponding to the single wing structures 48 to 58 is provided between the upper end side and the lower end side of the wing body 14, respectively.

Next, a casting method of the single-blade structures 42, 46, 48 to 58 will be described. As an example, the casting method of the single-blade structure 42 will be described, but other single-blade structures 46, 48 to 58 can be cast in the same manner. FIG. 8 is a schematic cross-sectional view showing the structure of the mold 60 for casting the single-blade structure 42. The arrow in FIG. 8 indicates the drawing direction of the mold 60. The mold 60 is made of ceramics or the like. The mold 60 includes a cavity 62 for forming the blade body 14 of the single blade structure 42, and a cavity 64 for forming the split shaft body 44 of the single blade structure 42. The mold 60 may be provided with a growth path (not shown) for growing crystals.

When the blade 14 of the single blade structure 42 and the split shaft 44 are formed of columnar crystals or single crystals, the cavity 62 and the cavity 64 of the mold 60 are pulled out at the same drawing speed and unidirectional solidification casting or Single crystal casting may be performed. For example, the mold 60 into which the molten Ni alloy is poured may be drawn out at a drawing speed of 100 mm / hour or more and 400 mm / hour or less by providing a temperature gradient at the solid-liquid interface and solidified. As a result, the Ni alloy grows in the same direction as the drawing direction of the mold 60, so that the drawing direction of the mold 60 becomes the crystal growth direction. When the blade body 14 is formed of columnar crystals or single crystals and the split shaft body 44 is formed of equiaxed crystals, the extraction speed of the cavity 64 may be faster than the extraction speed of the cavity 62. For example, the extraction speed of the cavity 62 may be 100 mm / hour or more and 400 mm / hour or less, and the extraction speed of the cavity 64 may be 1000 mm / min or more. Further, by applying the grain refiner to the portion corresponding to the cavity 64 in the mold 60, the equiaxed crystal can be further refined. A cobalt compound such as cobalt aluminate or cobalt oxide can be applied as the grain refiner.

In the assembly step, as shown in FIG. 7, a plurality of single-wing structures 42, 46, 48 to 58 are laminated in the axial direction. The plurality of single blade structures 42, 46, 48 to 58 are laminated so that the blade bodies 14 do not interfere with each other. A spigot or the like for positioning may be used for the plurality of single-wing structures 42, 46, 48 to 58. Then, the divided shafts of the plurality of single-wing structures 42, 46, 48 to 58 are integrally joined to each other. The joining method can be, for example, welding, diffusion welding, friction welding or the like. This makes it possible to manufacture turbine wheels.

As described above, according to the above configuration, the crystal growth direction of the wing body is the same as the centrifugal force direction, so that the creep strength of the wing body and the like can be increased. This makes it possible to improve the heat resistance of the turbine wheel. Further, according to the above configuration, since the turbine wheel is manufactured by casting a single blade structure in which the blade body and the split shaft body are integrated, it is possible to increase the mechanical strength between the blade body and the shaft body. can.

[Fourth Embodiment]
Hereinafter, the fourth embodiment of the present disclosure will be described in detail with reference to the drawings. The same components as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. The fourth embodiment is different from the third embodiment in the method of manufacturing the turbine wheel.

In the fourth embodiment, in the assembly step, a pin hole is formed in the split shaft of the single-wing structure so as to penetrate in the axial direction, and after the split shafts of the plurality of single-wing structures are laminated in the axial direction, the pin hole is formed. A pin made of Ni alloy is inserted into the split shaft, and the split shafts of a plurality of single-blade structures are joined together with the pin. Since the casting process of the fourth embodiment is the same as the casting process of the third embodiment, detailed description thereof will be omitted.

Next, the method for manufacturing the turbine wheel according to the fourth embodiment will be described in more detail. FIG. 9 is a schematic diagram for explaining a method for manufacturing a turbine wheel. The arrow in FIG. 9 indicates the crystal growth direction of the blade body 14. In FIG. 9, the turbine wheel is formed by assembling, for example, eight single-blade structures 70, 74, 78-88. The single wing structure 70 has a pin hole 72 in the axial direction of the split shaft body 44. The single-wing structure 70 may be formed by casting a pin hole 72 after casting the single-wing structure 42 of the third embodiment. Further, the single wing structure 74 has a pin hole 76 in the axial direction of the split shaft body 47. The single-wing structure 74 may be formed by casting a pin hole 76 or the like after casting the single-wing structure 46 of the third embodiment. The single-wing structures 78 to 88 are also formed in the same manner as the single-wing structures 70 and 74.

Next, the single wing structures 70, 74, 78 to 88 are laminated along the axial direction of the shaft body, and the pins formed of Ni alloy in the pin holes of the laminated single wing structures 70, 74, 78 to 88. (Not shown) is inserted and joined together. This improves the positioning accuracy of the single-blade structures 70, 74, 78 to 88 and facilitates the joining work. Further, by inserting the pin, the mechanical strength of the shaft body can be increased. The pins may be made of the same Ni alloy as the single blade structures 70, 74, 78-88. The joining method can be, for example, welding, diffusion welding, friction welding or the like. This makes it possible to manufacture turbine wheels.

According to the above configuration, the effect of the third embodiment is obtained, and the pin is inserted into the pin hole of the single-wing structure to be integrally joined, so that the single-wing structure can be easily joined. This can improve the productivity of the turbine wheel.

[Fifth Embodiment]
Hereinafter, the fifth embodiment of the present disclosure will be described in detail with reference to the drawings. The same components as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. The fifth embodiment is different from the first embodiment in the method of manufacturing the turbine wheel.

In the casting process, a plurality of two-blade structures in which two blades facing each other in a plurality of blades and one of a plurality of split shafts obtained by dividing the shaft in the axial direction are integrated are integrated. Is cast with a Ni alloy, and the two blades of the two-blade structure are unidirectionally solidified or single crystal cast. In the assembly step, after laminating the split shafts of the plurality of two-blade structures in the axial direction, the split shafts of the plurality of two-blade structures are integrally joined to each other.

Next, the method for manufacturing the turbine wheel according to the fifth embodiment will be described in more detail. FIG. 10 is a schematic diagram for explaining a method for manufacturing a turbine wheel. The arrow in FIG. 10 indicates the crystal growth direction of the blade body 14. In FIG. 10, the turbine wheel is formed by assembling, for example, four two-blade structures 90, 94 to 98. The shaft body is divided into four divided shaft bodies in the axial direction. In the two-blade structure 90, two blade bodies 14 facing each other with respect to the shaft body and a split shaft body 92 are integrally cast. The split shaft body 92 is provided on the upper end side of the two blade bodies 14. The two-blade structures 94 to 98 are also cast in the same manner as the two-blade structure 90. In the two-blade structure 98, the split shaft is provided on the lower end side of the two blades 14. In the two-blade structures 94 and 96, each split shaft corresponding to the two-blade structures 94 and 96 is provided between the upper end side and the lower end side of the two blade bodies 14.

Next, a casting method of the two-blade structure 90, 94 to 98 will be described. As an example, the method of casting the two-blade structure 90 will be described, but other two-blade structures 94 to 98 can be cast in the same manner. FIG. 11 is a schematic cross-sectional view showing the structure of a mold 100 for casting a two-blade structure 90. The arrow in FIG. 11 indicates the drawing direction of the mold 100. The mold 100 is made of ceramics or the like. The mold 100 includes a cavity 102 for forming one blade body 14 of the two-blade structure 90, a cavity 104 for forming the other blade body 14, and a split shaft body 92 of the two-blade structure 90. It is provided with a cavity 106 for forming the above. The mold 100 may be provided with a growth path (not shown) for growing crystals.

When the two blades 14 and the split shaft 92 in the two-blade structure 90 are formed of columnar crystals or single crystals, the cavities 102, 104 and 106 of the mold 100 are pulled out at the same drawing speed. One-way solidification casting or single crystal casting may be performed. For example, the mold 100 into which the molten Ni alloy is poured may be drawn out at a drawing speed of 100 mm / hour or more and 400 mm / hour or less with a temperature gradient provided at the solid-liquid interface to solidify. As a result, the Ni alloy grows in the same direction as the drawing direction of the mold 100, so that the drawing direction of the mold 100 becomes the crystal growth direction. When the two blades 14 are formed of columnar crystals or single crystals and the split shaft body 92 is formed of equiaxed crystals, the extraction speed of the cavity 106 should be faster than the extraction speed of the cavity 102 and the cavity 104. good. For example, the extraction speed of the cavity 102 and the cavity 104 may be 100 mm / hour or more and 400 mm / hour or less, and the extraction speed of the cavity 106 may be 1000 mm / min or more. Further, by applying the grain refiner to the portion corresponding to the cavity 106 in the mold 100, the equiaxed crystal can be further refined. A cobalt compound such as cobalt aluminate or cobalt oxide can be applied as the grain refiner.

In the assembly step, as shown in FIG. 10, the split shafts of the two-blade structure 90, 94 to 98 are laminated in the axial direction. The two blade structures 90, 94 to 98 are laminated so that the blades 14 do not interfere with each other. A spigot or the like for positioning may be used for the two-blade structure 90, 94 to 98. Then, the split shafts of the two-blade structures 90 and 94 to 98 are integrally joined to each other. The joining method can be, for example, welding, diffusion welding, friction welding or the like. This makes it possible to manufacture turbine wheels.

As described above, according to the above configuration, the crystal growth direction of the wing body is the same as the centrifugal force direction, so that the creep strength of the wing body and the like can be increased. This makes it possible to improve the heat resistance of the turbine wheel. Further, according to the above configuration, since the turbine wheel is manufactured by casting a two-blade structure in which two blade bodies and a split shaft body are integrated, the mechanical strength between the blade body and the shaft body is increased. Can be enhanced.

[Sixth Embodiment]
The sixth embodiment of the present disclosure will be described in detail below with reference to the drawings. The same components as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. The sixth embodiment is different from the fifth embodiment in the method of manufacturing the turbine wheel.

In the assembly process, a pin hole that penetrates in the axial direction is formed in the split shaft of the two-blade structure, and after laminating the split shafts of a plurality of two-blade structures in the axial direction, a Ni alloy is used in the pin hole. The formed pin is inserted, and the split shafts of the plurality of two-blade structures are integrally joined with the pin. Since the casting process of the sixth embodiment is the same as the casting process of the fifth embodiment, detailed description thereof will be omitted.

Next, the method for manufacturing the turbine wheel according to the sixth embodiment will be described in more detail. FIG. 12 is a schematic diagram for explaining a method for manufacturing a turbine wheel. The arrow in FIG. 12 indicates the crystal growth direction of the blade body 14. In FIG. 12, the turbine wheel is formed by assembling, for example, four two-blade structures 110, 114 to 118. The two-blade structure 110 has a pin hole 112 in the axial direction of the split shaft body 92. The two-blade structure 110 may be formed by casting a pin hole 112 or the like after casting the two-blade structure 90 of the fifth embodiment. The two-blade structures 114 to 118 are also formed in the same manner as the two-blade structure 110.

Next, the two-blade structures 110, 114 to 118 are laminated along the axial direction of the shaft body, and the laminated two-blade structures 110, 114 to 118 are formed of Ni alloy in the pin holes of the divided shaft bodies. Pins (not shown) are inserted and joined together. This improves the positioning accuracy of the two-blade structures 110 and 114 to 118, and facilitates the joining work. Further, by inserting the pin, the mechanical strength of the shaft body can be increased. The pins may be made of the same Ni alloy as the two-blade structures 110, 114-118. The joining method can be, for example, welding, diffusion welding, friction welding or the like. This makes it possible to manufacture turbine wheels.

According to the above configuration, the effect of the fifth embodiment is obtained, and the pin is inserted into the pin hole of the two-blade structure to be integrally joined, so that the two-blade structure can be easily joined. This can improve the productivity of the turbine wheel.

[Seventh Embodiment]
Next, the seventh embodiment of the present disclosure will be described in detail. The same components as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. The seventh embodiment is configured by combining the fifth embodiment or the sixth embodiment and the first embodiment. When the fifth embodiment and the first embodiment are combined, one blade is formed on the shaft body after the split shaft bodies of the two blade structures 90 and 94 to 98 are integrally joined to form a shaft body. The body 14 is joined and attached. When the sixth embodiment and the first embodiment are combined, a pin formed of a Ni alloy is inserted into a pin hole of a split shaft body of the two-blade structure 110, 114 to 118 and joined integrally. After forming the shaft body, one blade body 14 is joined and attached to the shaft body. As a result, the number of blades 14 of the turbine wheel can be made odd.

As described above, according to the above configuration, the crystal growth direction of the wing body is the same as the centrifugal force direction, so that the creep strength of the wing body and the like can be increased. This makes it possible to improve the heat resistance of the turbine wheel. Further, according to the above configuration, even when the turbine wheel is manufactured using the two-blade structure, the number of blades of the turbine wheel can be an odd number.

Since the present disclosure can improve the heat resistance of the turbine wheel, it can be applied to a turbine wheel for a supercharger such as a vehicle or a ship.

Claims (9)

Turbine wheel for turbocharger
A shaft body made of Ni alloy and
A plurality of blades provided around the shaft body and formed of columnar crystals or single crystals of Ni alloy in which the crystal growth direction and the centrifugal force direction are the same direction.
Equipped with a turbine wheel. The turbine wheel according to claim 1.
The shaft body is a turbine wheel formed of equiaxed crystals. It is a method of manufacturing turbine wheels for turbochargers.
A casting process in which the shaft body is cast with Ni alloy and multiple blades are unidirectionally solidified or single crystal cast with Ni alloy.
An assembly step of assembling the plurality of blades around the shaft body so that the crystal growth direction and the centrifugal force direction are in the same direction.
A method of manufacturing a turbine wheel. The method for manufacturing a turbine wheel according to claim 3.
In the casting process, the plurality of blades are cast with a single blade for each blade.
The assembly step is a method for manufacturing a turbine wheel in which the plurality of blade bodies are joined around the shaft body. The method for manufacturing a turbine wheel according to claim 4.
In the assembly step, a fitting groove into which the blade body can be fitted is formed around the shaft body along the axial direction, and the blade body is fitted into the fitting groove and joined. Production method. The method for manufacturing a turbine wheel according to claim 3.
In the casting step, a plurality of single-blade structures in which one of the plurality of blades and one of the plurality of split shafts obtained by dividing the shaft in the axial direction are integrally cast with a Ni alloy, and the casting is performed. The wing body of the single wing structure is unidirectionally solidified or single crystal cast.
The assembly step is a method for manufacturing a turbine wheel, in which the divided shafts of the plurality of single-wing structures are laminated in the axial direction, and then the divided shafts of the plurality of single-wing structures are integrally joined to each other. The method for manufacturing a turbine wheel according to claim 6.
In the assembly step, a pin hole penetrating in the axial direction is formed in the split shaft body of the single wing structure, and after laminating the split shaft bodies of the plurality of single wing structures in the axial direction, Ni is formed in the pin hole. A method for manufacturing a turbine wheel, in which a pin formed of an alloy is inserted and the split shaft bodies of the plurality of single-blade structures are integrally joined to the pin. The method for manufacturing a turbine wheel according to claim 3.
In the casting step, a plurality of 2 blades in which the two blades facing the shaft in the plurality of blades and one of the plurality of divided shafts obtained by dividing the shaft in the axial direction are integrated. The single-blade structure is cast with Ni alloy, and the two blades of the double-blade structure are unidirectionally solidified or single-crystal cast.
The assembly step is a method for manufacturing a turbine wheel, in which the split shafts of the plurality of two-blade structures are laminated in the axial direction, and then the split shafts of the plurality of two-blade structures are integrally joined to each other. The method for manufacturing a turbine wheel according to claim 8.
In the assembly step, a pin hole penetrating in the axial direction is formed in the split shaft body of the two-blade structure, and after laminating the split shaft bodies of the plurality of two-blade structures in the axial direction, the pin hole is formed. A method for manufacturing a turbine wheel, in which a pin formed of a Ni alloy is inserted into the pin, and the split shafts of the plurality of two-blade structures are integrally joined to the pin.

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