JP2012172589A - Method of manufacturing impeller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an impeller that can reduce blazing failure and shorten heat processing time.SOLUTION: When applying a heat cycle to an assembled body 15 in which blazing material composed of Au alloy containing Ni is arranged to a connection part of at least two impeller configuring members, a heating tool 20 configured by a cylindrical first heating part 21 and a discoid second heating part 22 integrally formed with the first heating part 21 is set to the assembled body. The heating tool 20 is configured by a material with a high heat conductivity, such as carbon. The first heating part 21 is inserted into an axial hole 16 of the assembled body 15, and the assembled body 15 is placed on an upper part of the second heating part with a spacer therebetween, and is set in a heating furnace 1 in which the heat cycle is processed. In a temperature rising process of the heat cycle, the first heating part 21 heats the assembled body 15 from an inner circumferential side. Thereby, a temperature distribution of the assembled body 15 is made uniform.

Description

  The present invention relates to a method for manufacturing an impeller (rotary blade) used in a centrifugal compressor and other rotating machines.

For example, as shown in FIG. 5, the impeller 10 of a centrifugal compressor is fixed to a rotating main shaft of a centrifugal compressor (not shown) via a shaft hole 16 provided on the inner peripheral side, and a disk 11 whose one surface is curved in a tapered manner. The cover 12 has a shape facing the curved surface of the disk 11, and a large number of blades 13 provided so as to partition the curved surface of the disk 11 and the cover 12 in a spiral shape.
The impeller 10 is a so-called three-piece type in which the disk 11, the cover 12, and the blade 13 are individually manufactured, joined to each other, and assembled. The cover 12 and the blade 13 (or the disk 11 and the blade 13). There is a so-called two-piece type in which the disc 11 (or the cover 12) is joined separately. In both the three-piece type and the two-piece type impellers 10, the joining is performed by welding or brazing. Whether the joining is performed by welding or brazing is determined by the size, strength, and the like of the impeller 10. The impeller 10 shown in FIG. 4 is a two-piece type, and shows an example in which a disk 11 and a cover 12 manufactured integrally with a blade 13 are joined by a brazing portion 14.

In the joining by brazing, a brazing temperature equal to or higher than the melting temperature of the brazing material with a brazing material made of, for example, an Au-Ni alloy interposed between the members to be joined (for example, between the disk 11 and the blade 13). It has a thermal cycle in which the temperature is raised to a low temperature and cooled after holding for a predetermined time.
The joining by brazing has the following advantages.
Since the brazing temperature and the temperature of the solution heat treatment of the material constituting the impeller 10 (precipitation hardening type stainless steel) can be set in the same temperature range, the heat treatment for brazing and the solution heat treatment can be combined. .
Moreover, compared with the impeller 10 produced by welding, there is less deformation and less unbalance.
Furthermore, since the brazing process is performed under vacuum, the surface of the impeller 10 after the process is cleaned, and the process for removing the oxide film can be reduced later, and the required dimensional accuracy can be easily ensured.

A method of manufacturing an impeller by brazing having such advantages is disclosed in Patent Document 1.
Although the quenching process was started at a temperature slightly lower than the liquid phase of the brazing material, this is not sufficient in the strength of the brazed joint, and as a result, cracks may occur in the brazed joint. The patent document 1 aims at solving the problem of the brazing method up to now.
Patent Document 1 proposes a brazing thermal cycle whose representative example is shown in FIG. In FIG. 1, the assembly to be brazed is heated to the liquid phase or liquidus temperature of the brazing material, about 1850 degrees Fahrenheit (1010 ° C.) for about 6 hours, and held at that temperature for about 1 hour. The temperature is maintained at 1200 degrees Fahrenheit (650 ° C.) for about 1 hour. Further, the brazed assembly is cooled to about 1300 degrees Fahrenheit (704.4 ° C.) over about 2 hours, and then the assembly is heated to a temperature of about 350 degrees Fahrenheit (176.7 ° C.) over 1 hour. Lower and gas quench. Patent Document 1 states that, due to this thermal cycle, the rotor blade assembly did not exhibit heat-induced distortion, and the brazed joints were all solid and cracks did not occur. Patent Document 1 contains JIS SUS630 as the stainless steel constituting each member of the impeller, and 80% to 85% gold (Au) and 15% to 20% nickel (Ni) as the brazing material. (Hereinafter, abbreviated as Ni-Au alloy) is recommended. In the present specification,% means mass.

Special table 2003-531731 gazette

As described above, according to Patent Document 1, it is said that an impeller can be produced by a brazing method without causing cracks.
However, when brazing is performed by the thermal cycle of Patent Document 1, there is a possibility that a gap may be generated between the disk 11 and the blade 13 that should be joined via the brazing material due to the generated temperature difference during the heat treatment. It has been found. Since the portion where the gap is generated is not joined via the brazing material (brazing failure), the impeller where the occurrence of the gap is remarkable is treated as a defective product, or brazing is performed again.
The present invention has been made based on such a problem, and an object of the present invention is to provide an impeller manufacturing method that can reduce brazing defects.

In order to investigate the cause of the brazing failure, the present inventors have studied from several directions. As a result, it was confirmed that a temperature distribution occurred in the impeller during the brazing heat cycle. When a temperature distribution is generated in the impeller, the interval between the bonding interfaces may be expanded due to a difference in the amount of thermal deformation generated accordingly. The brazing material melted in the thermal cycle is held in the gap by capillary action, but if the gap is too wide, the brazing material that cannot be held leaks to the outside.
Therefore, the present inventors have further studied paying attention to suppressing the expansion of the gap. It was found that the temperature distribution of the impeller mainly occurred on the inner peripheral side and the outer peripheral side of the impeller. Specifically, the temperature on the inner peripheral side of the impeller is lower than the temperature on the outer peripheral side. This is because the heating furnace that brazes the impeller is usually equipped with a heater only on the inner wall of the heating furnace, so that the temperature on the inner peripheral side of the impeller far from the heater is higher than that on the outer peripheral side near the heater. This is because it is difficult. Therefore, the present inventor has conceived the present invention as follows in order to complement the temperature increase on the inner peripheral side of the impeller (assembly).

According to the present invention, an assembly in which brazing material is arranged at a joint portion of at least two impeller components is held at a temperature raising process I for raising the temperature to the holding temperature and at a holding temperature in a temperature range higher than the melting temperature of the brazing material. It is related with the manufacturing method of the impeller which joins by giving the thermal cycle provided with the holding process II which performs temperature reduction process III which lowers temperature from holding temperature to room temperature, and heats an assembly from the inner peripheral side of an assembly It has the characteristic in performing a heat cycle in the state which has arrange | positioned the 1st heating body to do.
By arranging the first heating body that heats the assembly from the inner periphery side of the assembly, the temperature distribution on the inner periphery and the outer periphery of the assembly is reduced, and the expansion of the gap at the joint interface is suppressed. Can do. Therefore, according to the present invention, it is possible to perform brazing well.

It is preferable that the 1st heating body of this invention is integrally provided with the 2nd heating body which supports an assembly | attachment body from the downward direction of a perpendicular direction.
In addition to the inner peripheral side of the assembly, it is preferable to use a second heating body for positively supplying heat to the lower surface side of the assembly that is difficult to receive heat from the heater in the process of thermal cycling. By integrally configuring the second heating body and the first heating body, the operation of arranging the first heating body and the second heating body with respect to the assembly body becomes easy.

If the height of the first heating body is low with respect to the assembly, the amount of heat given from the first heating body to the assembly is small, so that the effect of reducing the temperature distribution may not be sufficiently obtained. On the other hand, even if the height of the first heating body is too high with respect to the assembly, the effect of reducing the temperature distribution cannot be obtained any more. Therefore, the first heater of the present invention preferably satisfies _{0.5h 2 ≦ h 1 ≦ 20h 2} . However, h ₁ is the height of the first heating element, h ₂ is the height of the assembled body.

  According to the present invention, when a brazing heat cycle is applied to an assembly made of a component member of an impeller, a heating body that heats the assembly member from the inner peripheral side is arranged, whereby the heat of the component member is arranged. It is possible to prevent the brazing interface from expanding due to the deformation and to suppress the brazing material defect.

It is a flowchart which shows the manufacturing process of the impeller in this Embodiment. It is sectional drawing which shows the assembly body and heating jig which were accommodated in the heating furnace. It is a figure which shows 1 pattern of the heat cycle at the time of brazing (solution heat treatment) in this Embodiment. It is a table | surface showing the observation result of the brazing condition of the sample obtained by fluctuating the height and thermal cycle of the 1st heating part at the time of brazing (solution heat treatment). An example of the impeller of a centrifugal compressor is shown, (a) is a top view, (b) is a half sectional view along the blade of the impeller.

Hereinafter, the present invention will be described in detail based on embodiments. Note that a series of steps described below is shown in FIG.
In the present embodiment, a two-piece impeller shown in FIG. 5 will be described as an example. However, it goes without saying that the present invention can also be applied to the production of a two-piece impeller or a three-piece impeller in which the blade 13 is formed integrally with the disk 11.

<Material for covers and discs>
Materials for the disk 11 and the cover 12 are prepared. This material is provided as a rod-shaped steel material. This material basically has the following chemical composition (mass%) defined by SUS630. SUS630 is a precipitation hardening type stainless steel that improves the strength of the steel by dissolving Cu in the matrix by a solution heat treatment and then precipitating a fine Cu-Ni intermetallic compound by a subsequent age hardening heat treatment. In addition to the following elements, elements that can improve the properties of SUS630 may be included.

<SUS630 chemical composition (reference value)>
Cr: 15.5% to 17.5% (preferably 15.5% to 17.0%)
Ni: 3.0% to 5.0% (preferably 3.5% to 4.5%)
Cu: 3.0% to 5.0% (preferably 3.0% to 4.0%)
Nb + Ta; 0.15% to 0.40% (preferably 0.3% to 0.40%)
C; 0.07% or less Si; 1.0% or less Mn; 1.0% or less P; 0.004% or less S; 0.03% or less Remainder; Fe and inevitable impurities

<Forging-cutting>
The material for the disk 11 and the cover 12 is processed into the shape of the disk 11 and the cover 12 by forging and cutting, respectively. A shaft hole 16 is formed at the radial center of the disk 11. For example, the rotary main shaft of the centrifugal compressor is fitted into the shaft hole 16. Since the cover 12 is integrally provided with the blade 13, cutting is performed to form the blade 13.

<Assembly>
The disk 11 and the cover 12 integrated with the blade 13 are assembled by abutting each joint surface side. The cover 12 has the blade 13 side opposed to the joining surface side of the disk 11. A brazing material is disposed on the abutting surface. At this time, in order to secure the thickness of the brazing material after brazing, a jig can be used so as to maintain a distance between the abutting surfaces of the disk 11 and the cover 12.

<Brazing material>
The brazing material used in the present embodiment is an alloy containing Ni based on Au. This brazing filler metal contains 15 to 20% Ni, and the balance is made of Au and inevitable impurities. By setting it as this composition range, the wettability with respect to a base material (the disk 11 and the braid | blade 13) is favorable, and high joint strength can be obtained. This gold brazing material has a melting point (liquidus temperature) of 900 to 1050 ° C. which is lower than the holding temperature of the solution heat treatment of SUS630. This gold brazing material preferably has a chemical composition of 16-19% Ni-81-84% Au, more preferably 17.5-18.5% Ni-81.5-82.5% Au. This gold brazing material typically has a composition of 18% Ni—Au and has a melting point of 900-1000 ° C.
The form of the brazing material interposed between the abutting surfaces of the disk 11 and the cover 12 is arbitrary. For example, any of those known in brazing may be used, such as a thin piece, a thin strip, a linear material, a powder, or a paste. However, it is necessary to satisfy the thickness of the brazing material after brazing that is set in order to ensure the toughness of the joint portion.

<Assembly and heating jig>
The assembly 11 is obtained by assembling the disk 11 and the cover 12 (blade 13) through a brazing material. As shown in FIG. 2, the assembly 15 is accommodated in the heating furnace 1 that performs heat treatment in a state where the assembly 15 is disposed in the heating jig 20. In the present embodiment, the shaft hole 16 of the assembly 15 described below is the same as the shaft hole 16 of the disk 11. Further, the side of the assembly 15 close to the shaft hole 16 is the inner peripheral side of the assembly 15 and the far side is the outer periphery.

As shown in FIG. 2, the heating jig 20 is integrally formed with a cylindrical first heating part (first heating body) 21 inserted into the shaft hole 16 of the assembly 15 and the first heating part 21. And a disk-shaped second heating part (second heating body) 22 that supports the assembly 15 from below in the vertical direction.
The heating jig 20 is made of carbon having a high thermal conductivity, and is heated by heat generated from a heater (not shown) provided on the inner furnace wall 2 of the heating furnace 1 during a thermal cycle described later. The heated first heating unit 21 heats the assembly 15 from the inner peripheral side.
In the heating jig 20, the first heating unit 21 and the second heating unit 22 can be separately manufactured, and these can be joined and integrated later, or the first heating unit 21 and the second heating unit. 22 can be manufactured as a unit from the beginning.
In addition to carbon, a metal material having a heat resistance of 1000 ° C. or higher can be used as a material constituting the heating jig 20.

The size of the heating jig 20 is appropriately adjusted depending on the size of the assembly 15 to be arranged, but the height (h ₁ ) of the first heating unit 21 is the vertical height (h ₂ ) of the assembly 15. ) Is preferably 0.5 times or more. When h ₁ is less than 0.5h ₂ of h _2, the temperature is unlikely to increase in the heating furnace 1 for the heat of the heater is blocked by the assembled body 15 first heating portion 21, the inner circumferential side of assembly 15 Can not be heated sufficiently.
On the other hand, when h ₁ is increased and, for example, as shown in FIG. 2, the first heating unit 21 is configured to protrude from the shaft hole 16 of the assembly 15, heat is generated from the heater of the heating furnace 1. Therefore, the first heating unit 21 is heated to a higher temperature. The heated first heating unit 21 heats the assembly 15 from the inner peripheral side. Thus, the 1st heating part 21 heats the inner peripheral side of the assembly 15, and thereby the inner periphery of the assembly 15 and the outer periphery of the assembly 15 heated by the heater of the heating furnace 1. The temperature distribution can be made more uniform. By making the temperature distribution more uniform, the difference in the amount of thermal deformation in the assembly 15 is reduced, and the expansion of the gap at the joining interface between the disk 11 and the cover 12 is suppressed. As a result, the brazing material can be maintained at the joining interface, and the disk 11 and the cover 12 can be brazed well. In addition, since the assembly 15 is heated from the inner peripheral side by the first heating unit 21, even if the temperature increase rate of the thermal cycle is increased, the temperature distribution is hardly generated in the assembly 15. Therefore, the temperature increase rate of the thermal cycle can be increased and the required time of the entire thermal cycle is shortened, so that the manufacturing cost can be reduced.
However, even if the 1st heating part 21 is too high, the effect of temperature distribution reduction cannot be acquired any more. In addition, the operation of placing the assembly 15 on the heating jig 20 is not easy, and the manufacturing cost of the heating jig 20 itself increases. Therefore, the height of the first heating unit 21 may be configured to satisfy 0.5h ₂ ≦ h ₁ ≦ 20h ₂ , more preferably h ₂ ≦ h ₁ ≦ 10h ₂ .

Moreover, it is preferable that the first heating unit 21 is configured not to contact the assembly 15 when inserted into the shaft hole 16 of the assembly 15. When the first heating unit 21 comes into contact with the assembly 15, a material such as carbon constituting the first heating unit 21 may move to the surface layer of the assembly 15 and a composition change may occur in the assembly 15. Because. On the other hand, when the diameter of the 1st heating part 21 is too small, the surface area of the 1st heating part 21 exposed to the heater of the heating furnace 1 will also become small, and the assembly 15 can fully be heated from the inner peripheral side. Can not. Accordingly, the radial size of the first heating unit 21, diameter _{R 1} of the first heating portion 21, the diameter of the axial hole 16 When _{R 2, 0.4R 2 ≦ R 1} <R 2, and more preferably , 0.8R ₂ ≦ R ₁ <0.95R ₂ is preferably satisfied.

The second heating unit 22 is preferably configured to have a diameter equal to or greater than the outer diameter of the assembly 15. As a result, it is possible to stably support the assembly 15 and to suppress thermal deformation (warpage) on the outer peripheral side of the assembly 15 to a certain extent. The thickness of the second heating unit 22 is appropriately adjusted according to the height (h ₁ ) of the first heating unit 21 and the size of the heating furnace 1.

<Arrangement of assembly on heating jig>
The first heating part 21 of the heating jig 20 is inserted into the shaft hole 16 of the assembly 15, and the assembly 15 is disposed on the heating jig 20. At this time, a spacer (not shown) made of ceramic or the like that is stable at a holding temperature described later can be interposed between the second heating unit 22 and the assembly 15. If the assembly 15 is placed directly on the second heating unit 22, a material such as carbon constituting the second heating unit 22 may move to the surface layer of the assembly 15, causing a composition change in the assembly 15. Because there is.
The assembly 15 is disposed on the heating jig 20 so that the disk 11 side is positioned upward, but the cover 12 side may be positioned upward.

<Heat treatment (brazing heat cycle)>
The assembly 15 thus arranged on the heating jig 20 is inserted into the heating furnace 1 and heat treatment is started. As shown in FIG. 1, the heat treatment is composed of two stages of a solution heat treatment and an age hardening heat treatment. The solution heat treatment is performed under vacuum and the age hardening heat treatment is performed at a vacuum or equivalent to atmospheric pressure. The brazing heat cycle is performed in combination with the solution heat treatment. Hereinafter, it is collectively referred to as a brazing heat cycle. The age hardening heat treatment can be performed after the brazing heat cycle (solution heat treatment) is completed. Hereinafter, suitable conditions for a series of heat treatments will be described.

[Brazing heat cycle]
As shown in FIG. 3, the brazing heat cycle can be divided into a heating process (I), a holding process (II), and a cooling process (III).
The temperature raising process is usually started from room temperature, and the temperature in the furnace (the assembly 15 and the heating jig 20) is raised to the holding temperature.
[Heating process]
In the present embodiment, by using the heating jig 20, the temperature in the assembly 15 is increased during the temperature rising process even if the temperature rising rate during the temperature rising process is set in the range of 100 to 400 ° C./hr. It is possible to suppress the distribution so that the brazing material does not leak out from the joint interface. Moreover, the temperature increase rate in the temperature increasing process is preferably 120 to 380 ° C./hr., More preferably 140 to 360 ° C./hr.
The time required for the temperature raising process cannot be unambiguously determined because it is caused by the rate of temperature rise, the time required for intermediate holding described below, or the size of the impeller 10, but considering the manufacturing cost of the impeller 10, It is desirable to make it 30 hours or less.

  The above temperature increase rate is applied to the entire temperature increase process. That is, it is applied during the period from when the temperature increase is started until the holding temperature (holding process) is reached. However, this temperature increase rate is not applied during the intermediate holding described below. Further, the rate of temperature rise need not be constant and can be varied in the range of 100 to 400 ° C./hr. Typically, in a temperature range exceeding 950 ° C., selecting a heating rate slower than that in a temperature range lower than that is listed.

[Intermediate retention]
In the temperature raising process, an intermediate holding for maintaining the temperature can be provided. By providing the intermediate holding, the temperature distribution of the assembly 15 can be made more uniform. Intermediate holding can be performed in a temperature range of 500 to 950 ° C.
In the present embodiment, the intermediate holding is allowed to be performed in two stages (hereinafter, the first intermediate holding is referred to as the first intermediate holding, and the second intermediate holding is referred to as the second intermediate holding). To describe).
The first intermediate holding can be performed in a temperature range of 500 to 850 ° C. By performing before the temperature range (around 950 ° C.) at which the brazing material melts, the effect of reducing the gap at a relatively low temperature can be obtained. The first intermediate holding is preferably performed in a temperature range of 550 to 750 ° C, more preferably in a temperature range of 550 to 700 ° C.
The second intermediate holding can be performed in a temperature range of 850 to 950 ° C. (not including 850 ° C.). In the temperature raising process, the temperature distribution generated in the assembly 15 increases as the temperature relatively increases. Therefore, the temperature of the assembly 15 is further uniformized by providing the second intermediate holding in the high temperature range. be able to. The second intermediate holding is preferably performed in the temperature range of 860 to 940 ° C, more preferably in the temperature range of 880 to 920 ° C.

  The holding time in the first intermediate holding should be determined according to the size of the assembly 15 and the like, but the effect of temperature equalization is insufficient in a short time, and the temperature equalization is performed for a certain time. It is preferable that the time is 1 to 10 hours. A more preferable holding time is 2 to 8 hours. This holding time is the same for the second intermediate holding.

[Slow heating]
Until the transition to the holding process after the first intermediate holding, the heating rate can be made slower than the heating rate before the first intermediate holding. Since the brazing material starts to melt after the second intermediate holding, the temperature increase rate is suppressed as much as possible in order not to cause a temperature distribution in the assembly 15. However, the temperature rising rate in this case is also preferably selected from the range of 100 to 400 ° C./hr. The same can be said for the rate of temperature rise after the second intermediate holding until the shift to the holding process.

[Holding process (solution heat treatment)]
The holding process has a function of melting the brazing material together with a function of holding the base material (impeller 10) in the solution heat treatment.
The holding temperature in the holding process can be selected from the range of 1000 to 1050 ° C. The range of this holding temperature basically conforms to JIS G4303 that defines the heat treatment of SUS630. The holding time of this temperature can be preferably selected from the range of 0.5 to 3 hours.

[Cooling process]
The temperature lowering process after the holding process is preferably set to a speed in the range of 20 to 100 ° C./hr. In order to suppress the temperature distribution of the assembly 15 as in the temperature increasing process. Moreover, if this temperature-fall rate, the objective of the solution heat treatment that makes Cu dissolve in the base in SUS630 can be achieved.
In this temperature lowering process, it is preferable that the temperature is lowered from the holding temperature to 950 ° C. at a speed slower than the temperature lowering speed. This is the same purpose as raising the temperature in the temperature range exceeding 950 ° C. at a slower rate than before. In order to make this point clearer, a holding for 0.5 to 2 hours can be provided in the vicinity of 950 ° C., specifically in the range of 930 to 970 ° C.
Further, in the temperature lowering process, after the temperature falls to 600 ° C. or lower, the temperature lowering rate can be set to 100 ° C./hr. Or higher by supplying a cooling gas.

  Since the above-mentioned gold brazing material has a melting point of 900 to 1050 ° C., the disk 11 and the cover 12 are brazed by melting and solidifying in the course of the solution heat treatment including the temperature lowering process. In addition, in order to make a structure | tissue into a martensite, it is necessary to reduce to Mf point (Martensite transformation completion temperature), The temperature is 100-140 degreeC although it depends on a composition and a cooling rate, This temperature is after holding | maintenance. It is necessary to cool to the following.

[Retention process (aging hardening heat treatment)]
When the brazing (solution heat treatment) is completed, age hardening heat treatment is then performed.
The age hardening heat treatment is performed according to JIS G4303. JIS G4303 classifies the temperature of age-hardening heat treatment according to the desired tensile strength and yield strength, but any temperature can be adopted in the present invention, and the temperature between the temperature ranges defined in JIS G4303 is adopted. You can also

<Experimental example>
A disk 11 having the form shown in FIG. 5 and a cover 12 in which a blade 13 is integrally formed are prepared, and a brazing material (thickness: 100 μm) is interposed between the disk 11 and the blade 13 to assemble the assembly. 15 was obtained. With the assembly 15 placed on the carbon heating jig 20, brazing (solution heat treatment) is performed under various conditions, and then the brazing state is confirmed by water depth ultrasonic flaw detection. It was evaluated with.
○: Brazing defects are not observed. Δ: Brazing defects are scattered. X: Brazing defects are scattered. The chemical composition of the steel material constituting the disk 11 and the cover 12 (blade 13) and the composition of the brazing material are as follows. It is. Further, the height (h ₁ ) and brazing (under vacuum) conditions of the first heating unit 21 of the heating jig 20 are as shown in FIG.

Chemical composition of steel (conforming to JIS SUS630):
Cr; 15.5%, Ni; 4.3%, Cu; 3.5%, Nb + Ta; 0.35%
C; 0.05% Si; 0.25%, Mn; 0.8%, P; 0.0035%, S; 0.007%
Remainder; Fe and inevitable impurities Composition of brazing material: 18% Ni-82% Au

As shown in FIG. From 1 to 9, it became clear that brazing is performed well by providing the first heating unit 21 and performing heat treatment. Sample No. 10 and 11, it was found that when the rate of temperature increase was increased, brazing was performed better when the height (h ₁ ) of the first heating unit 21 was higher.

In the above-described embodiment, the temperature of the first heating unit 21 is increased by the heat generated from the heater of the heating furnace 1 and the inner peripheral side of the assembly 15 is heated. However, the present invention is not limited to this configuration. . For example, a cylindrical carbon heater that itself generates heat can be used as the first heating unit 21. Alternatively, the entire heating jig 20 including not only the first heating unit 21 but also the second heating unit 22 can be a heater that generates heat.
In addition to this, as long as it does not depart from the gist of the present invention, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

  DESCRIPTION OF SYMBOLS 1 ... Heating furnace, 2 ... Inner furnace wall, 10 ... Impeller, 11 ... Disk, 12 ... Cover, 13 ... Blade, 14 ... Brazing part, 15 ... Assembly | attachment body, 16 ... Shaft hole, 20 ... Heating jig, 21 ... 1st heating part (1st heating body), 22 ... 2nd heating part (2nd heating body)

Claims (3)

In the assembly in which the brazing material is arranged at the joint portion of at least two impeller components,
A temperature raising process for raising the temperature to the holding temperature;
A holding process for holding at a holding temperature in a temperature range higher than the melting temperature of the brazing material;
A temperature lowering process for lowering the temperature from the holding temperature to room temperature, and a method for manufacturing an impeller that is joined by performing a thermal cycle including:
The thermal cycle is
A method for manufacturing an impeller, wherein the assembly is disposed on a first heating body that heats the assembly from the inner peripheral side of the assembly. The first heating body is provided integrally with a second heating body that supports the assembly from below in the vertical direction.
The method for manufacturing an impeller according to claim 1. The first heating body is
0.5h ₂ ≦ h ₁ ≦ 20h ₂
Satisfy,
The manufacturing method of the impeller of Claim 1 or 2.
However, h ₁ is the height of the first heating element, h ₂ is the height of the assembled body.

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