JP2003328989A - Impeller manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an impeller having high reliability as an effective means for relaxing stress concentration wherein man-hours of machining is reduced to a half, and stress concentration is relatively easily relaxed at a low cost in comparison with R-part forming by fillet weld and grinder finish without limitation of plate thickness and tilting of blades. <P>SOLUTION: A plating layer is provided in both of a combination of a unit of a blade and an upper shroud with a lower flat shroud and a combination of a unit of a blade and a lower shroud with a flat upper shroud. The upper shroud or the lower shroud provided with a groove having an R-part in both sides thereof are made to abut on each other, and surface roughness of bonding surfaces is set at 3 μm or less, and bonding and diffusion processing of the bonding surfaces are continuously performed in a vacuum furnace, and thereafter, quenching and tempering are performed to manufacture the impeller. Since the groove having the R-part is provided in both sides of the blade, stress concentration to a blade fitting part is relaxed to improve the fatigue strength, and the impeller restricted in thermal deformation thereof due to the welding structure is manufactured at a low cost. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an impeller of a pump, a centrifugal compressor and a blower, or an impeller to which diffusion bonding is applied for manufacturing a turbo impeller.

[0002]

2. Description of the Related Art As a method of manufacturing a structure requiring a space with a narrow gap such as an impeller for a compressor, integral manufacturing by a precision casting method or a method of removing a narrow gap portion by electric discharge machining,
There are methods such as solid phase diffusion bonding, but the surface roughness is rough.
Since there are many problems such as high cost and a lot of time, a method of assembling and manufacturing by welding has been conventionally used.

The diffusion bonding method of metallurgically bonding by heating while applying a compressive force to a bonding portion with a low melting point bonding material interposed therein causes thermal deformation or deformation as compared with a conventional welding method accompanying melting of a base material. It has an excellent feature that there is little change in chemical organization. Diffusion bonding uses a solid phase diffusion bonding method in which the end faces of the materials to be joined are butt-joined in the solid state regardless of the presence or absence of the low melting point bonding material and the low melting point bonding material is used to form a liquid between the materials to be bonded. There are two types of liquid-phase diffusion bonding methods in which bonding is performed with a phase interposed. Compared with the solid-phase diffusion bonding method which requires a long time in a high vacuum, the liquid-phase diffusion bonding method has a feature that the time required for bonding can be dramatically shortened. A method for manufacturing an impeller that makes use of the characteristics of such a liquid phase diffusion bonding method,
JP-A-5-202701, JP-A-6-27269
No. 6 publication.

In Japanese Unexamined Patent Publication (Kokai) No. 5-202701, continuous protrusions are provided on the blade so as to surround the joint surface, and the joint surfaces of the blade and the flat plate are brought into contact with each other. Then, a joining method in which diffusion joining is performed on the remaining recesses under high temperature and hydrostatic pressure, and a joining method characterized by further forming a fillet by brazing at the corner portion of the joining surface in a vacuum is described. ing.
In Japanese Unexamined Patent Publication No. 6-272696, a partial plating layer by electroless Ni-P plating (P concentration: 9 to 10%) with a plating thickness of 3 μm is applied to the blade joining surface of the impeller and its periphery, and both members are provided. It is described that the blade joining surfaces of the above are abutted with each other.

[0005]

When the joining is carried out by these methods except when the joining is made at the central portion of the blade, the blade root portion which is the stress concentration portion does not have a smooth R shape and the fatigue strength is lowered. Cause It has been experimentally experienced that the R shape of the blade root has almost no effect by the method using a brazing material as described in JP-A-5-202701.

According to the conventional method for manufacturing an impeller by diffusion bonding, as shown in FIG. 8, a member in which the upper shroud portion 2 and the blade portion 3 are integrated, the lower shroud portion 4, and the blade portion are provided. The method of joining the member in which 3 is integrated is not effective because of high cost due to increased machining. Further, the pressure applied in the diffusion bonding is 14.7 to 29.4 MPa, which is 2 to 5 times the pressure applied in the liquid phase diffusion bonding, so that there are many restrictions on the blade thickness, inclination, and the like. In addition, the connection part between the existing blade and the upper shroud is MIG or TIG.
Even when fillet welding is performed using welding, it is necessary to finish the grinder only at the toe. In the method of directly liquid phase diffusion bonding the blade to the main plate such as the shroud, there is a problem that stress concentrates on the bonding surface.

The present invention is an effective means for alleviating stress concentration, and is a highly reliable impeller that can reduce stress concentration easily and at low cost as compared with machining by half and fillet welding and grinder finishing. The purpose is to provide a manufacturing method.

[0008]

In order to solve the above-mentioned object, the present invention provides a combination of a blade and an upper shroud integrated with a flat lower shroud, or a combination of the blade and the lower shroud with a flat surface. A plating layer is provided on both of the joint surfaces formed by combining the upper shrouds. For this purpose, a groove having an R portion is provided on both sides to form a void portion to form a plating layer. The surface roughness of the joint surface of the upper shroud or the lower shroud is 3 μm or less (0.5 to 3.0 μm).
m), a method for manufacturing an impeller is provided, wherein the joining and the diffusion process of the joining surface are consistently performed in the vacuum furnace, and then the quenching process and the tempering process are performed. By providing grooves with R portions on both sides of the blade, stress concentration at the blade root is relaxed (formation of concentrated concentration relaxation groove), fatigue strength is improved, and low-cost blade with less thermal deformation due to the welded structure. Cars can be manufactured.

1.5 μm (0.5 to 1.
5 μm thick) plating layer and the surface roughness of the joint surface is 3 μm
By setting the thickness to the following (0.5 to 3.0 μm) and performing the bonding and the diffusion treatment in a vacuum, a sound bonding structure without unwelded defects can be obtained.

The plating layer is a commercially available precipitation hardening stainless steel, SUS630 or SC, which is a material for the impeller.
As a temperature material equivalent to the vacuum heat treatment temperature of M430, N
By using the iP plating material, the bonding surface is integrated through the plating layer by bonding and diffusion treatment.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The method for manufacturing an impeller of the present invention will be described in detail below. As shown in FIGS. 1 (a) and 1 (b) of FIG. 1, an impeller 1 includes a circular lower shroud 4 having an opening at its center and the lower shroud 4 while drawing a constant curve. A plurality of blades 3 are attached radially from the central portion to the outer peripheral portion, and a circular upper shroud 2 having an opening in the central portion.

As shown in FIGS. 2 (a) and 2 (b), the manufacturing method of the impeller 1 uses a material of commercially available precipitation hardening stainless steel SUS630 or SCM430, and A circular lower shroud 4 having an opening in a portion has a plurality of blades 3, and the blades 3 of the lower shroud 4 in which grooves 10 and 10A having an R portion shown in FIG. The plating layer 5 and the plating layer 50 formed on the upper shroud portion 2 as described below are butted against each other and pressed in vacuum.

As shown in FIG. 2, the method of joining the upper and lower shrouds 2 and 4 to the blade 3 is as follows. Liquid-phase diffusion bonding through 5, 50,
(B) There is one in which the lower shroud 4 and a member formed by integrally forming the blade 3 and the lower shroud 4 are liquid-phase diffusion bonded via the plated layers 5 and 50 provided on both sides.

FIG. 3 shows how the impeller 1 is joined by liquid phase diffusion joining. In the case of FIG. 2 (a), the liquid phase diffusion bonding of the impeller 1 is a groove having an R portion with the lower shroud 4 and the blade 3 integrated in the vacuum heating / pressurizing device 6 and the plating layer 5. Upper shroud 2 provided with 10 on both sides of blade 3
Are superposed on each other and pressurized by a pressure device 8 at a low pressure of 9.8 MPa or less, and the inside of the furnace is bonded while being kept in a prescribed vacuum atmosphere. The same applies to the case of FIG.
In the case shown in FIG. 2B, the joining is performed in the steps shown in FIG. 5, but the method is the same as the case shown in FIG. 4, and the description will not be repeated. Formed in a shroud.

In FIG. 4, the plating layer 5 applied to the blade 3 in which the blade 3 and the upper shroud 2 are integrated, and the lower shroud 4 are R-shaped.
Characterized in that it is superposed with the plating layer 50 formed on the projection 21 on the blade formed by the two arc-shaped grooves 10 and 10A having a portion, and is pressed at a low pressure of 9.8 MPa or less in vacuum. It shows a method of manufacturing the impeller. As shown in the figure, the projection 21 is formed by two arcuate grooves 10 and 10A spaced apart from each other on the side plate side of the upper shroud on the blade side. The root portion of the blade 3 is an R portion 11.
Through the steps of FIGS. 4A and 4B, liquid phase diffusion bonding is performed as shown in FIG. 4C to form the diffusion portion 51.
The impeller 1 is a rotating body, and as the rotation speed increases,
Since a large combined stress of centrifugal stress and vibration stress is received, it is indispensable to form the weld toe shape into a smooth R shape at the blade root portion, which is a stress concentration portion.

In the case of the diffusion bonding of the conventional patent shown in FIG. 8, in forming the diffusion layer 51, a member in which the upper shroud 2 and the blade portion 3A are integrated, the lower shroud 4, and the blade portion 3 are formed.
In order to process the member in which B is integrated, all of the cutting is performed by machining, so that the material cost is wasted and the cost increase due to an increase in the processing cost is a bottleneck.

In view of this point, the present invention is directed to the upper shroud 2
Upper shroud 2 in which the blade and the blade 3 have an R portion 11
Groove 1 having the R part of the lower shroud 4 as the plating layer 5 of
0 and 10A, and the plating 50 applied to the protrusions 21 are overlapped and pressed at a low pressure of 9.8 MPa or less,
It is to join. The R diameter and depth of the grooves 10, 10A provided on both sides of the lower shroud 4 for relaxing stress concentration are
It is determined by the thickness of the lower shroud 4. In order to relax the stress, the depth of the grooves 10 and 10A can be set to about 1/3 to 1/4 of the plate thickness of the lower shroud 4.

Since the impeller 1 is a rigid body in which a plurality of blades 3 are radially installed between the upper and lower shrouds 2 and 4, a groove is provided for stress relaxation about 1/3 to 1/4 of the plate thickness. 1
Even if 0 and 10 A are provided, the strength does not decrease. Groove 1
When 0 and 10A are provided on both sides of the lower shroud 4, by the way, when the thickness of the lower shroud is 10 mm, it is sufficient that the grooves 10, 10A provided on both sides are about R3. Cost reduction is shown in Fig. 8.
The cost reduction is obvious when compared with the conventional method of cutting the entire surface of the upper and lower shrouds of diffusion bonding by machining.

FIG. 6 shows a blade layer 3 having an inclination 12 and an upper shroud 2 which are integrally formed, and a lower shroud 4 having grooves 10 and 10A having R portions on both sides.
In the same manner as shown in (1), they are superposed and pressed and joined at a low pressure of 9.8 MPa or less. Compared to diffusion bonding, there is no deformation such as blade tilt due to the inclination 12 due to the low pressure. In the case corresponding to FIG. 2B, the protrusion 21 is formed on the upper shroud 2 as described above.

FIG. 7 shows an installation example of the grooves 10 and 10A having an R portion. For example, when the lower shroud 4 and the blade 3 are joined via the diffusion layer 51, the positions of the grooves 10 and 10A must be the contact points between the blade 3 and the lower shroud 4. That is, the grooves 10 and 10A have no stress relaxation effect at a position apart from the blade 3. Also,
The shapes of the grooves 10 and 10A are semicircular, and the concave shape is not effective because stress concentration occurs. Here, it is referred to as an arc shape, but this means that it is a stress relaxation groove shape.

The grooves 10, 10A are installed along the both sides of the blade 3 from 1/3 of the plate thickness when the blade shape in FIG. 7 (a) is a two-dimensional blade shape having a straight line or an inclination on the circumference. 1 /
It is installed in a semicircular shape with a depth of about 4. 7 (b) When the blade shape is a three-dimensional blade shape having an arc on the circumference, it is installed along both sides of the blade 3 in a semicircular shape with a depth of about 1/3 to 1/4 of the plate thickness. To be done. Groove 10 for stress relaxation,
10A is (a) when joining the blade to the upper shroud,
It is essential when joining (b) and the vane with the lower shroud.

The plating layers 5 and 50 are indispensable for liquid phase diffusion bonding, and the stress relaxation groove is provided in either of the upper and lower shrouds 2 and 4 as described above, and the plating layers 5 and 50 are used for the liquid diffusion. By using phase diffusion welding, the shrinkage rate is reduced and the manufacturing method can be applied to many types of impellers.
By the way, solid-phase diffusion bonding does not require a plating layer, but it has a small shrinkage ratio, so the blade thickness is large, and so there are few applicable models.

FIG. 9 is a flow chart showing the manufacturing method of the impeller of the present invention. In the example (b) of the manufacturing method of the impeller shown in FIG. 2, first, the blade and the upper shroud 2 are integrally formed (accuracy 0.5 to 3.0 μm), and the lower shroud 4 is similarly processed (accuracy 0. 5 to 3.0 μm), followed by plating of the processed product (0.5 to 1.5 μm), liquid phase diffusion bonding, and heat treatment such as quenching and tempering to complete the process.

FIG. 10 is a comparison diagram of solid phase diffusion bonding and liquid phase diffusion bonding. From the figure, it can be seen that the liquid phase diffusion bonding has a small pressing force and a small shrinkage ratio, and that many impeller models are applicable. FIG. 11 shows the chemical composition of the plating material used for liquid phase diffusion bonding. It can be seen that the Ni-P plating used in the present invention has a low brazing temperature and is advantageous.

[0025]

According to the method for manufacturing an impeller of the present invention, tilting of the blade portion due to low pressure and deformation of contraction are eliminated, and fatigue strength is improved by relaxing stress concentration due to the effect of the grooves 10, 10A having the R portion. Can provide a highly reliable impeller.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a method for manufacturing an impeller to which the present invention is applied.

FIG. 2 is a schematic view of a method for manufacturing a liquid phase diffusion bonding impeller to which the present invention is applied.

FIG. 3 is a schematic view of a liquid phase diffusion bonding vacuum heating / pressurizing manufacturing apparatus to which the present invention is applied.

FIG. 4 is a schematic diagram of a method for manufacturing an impeller to which the present invention is applied.

FIG. 5 is a schematic view of another manufacturing method of the impeller to which the present invention is applied.

FIG. 6 is a schematic diagram of a method for manufacturing an impeller to which the present invention is applied.

FIG. 7 is a schematic diagram of a method for manufacturing an impeller to which the present invention is applied.

FIG. 8 is an explanatory view of a manufacturing method of a conventional impeller.

FIG. 9 is an explanatory diagram of a flow chart for manufacturing an impeller.

FIG. 10 is a comparison diagram of conditions of solid phase diffusion bonding and liquid phase diffusion bonding.

FIG. 11: Components of materials used for liquid phase diffusion bonding and brazing temperature.

[Explanation of symbols]

1 ... Impeller, 2 ... Upper shroud (first shroud), 3
... blades, 3a ... straight or inclined two-dimensional blade shape, 3
b ... Three-dimensional blade shape having an arc, 4 ... Lower shroud (second shroud), 5, 50 ... Plating layer, 51 ... Diffusion layer,
6 ... Vacuum pressurizing and heating manufacturing device, 7 ... Vacuum pump, 8 ... Pressurizing device, 9 ... Heating device, 10 and 10A ... Grooves for stress relaxation, 11 ... R part, 12 ... Inclination.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiromi Kobayashi             4-13 Nakagawa Adachi-ku, Tokyo Stock Exchange             Inside Hitachi Industries (72) Inventor Kenji Yaegashi             4-13 Nakagawa Adachi-ku, Tokyo Stock Exchange             Inside Hitachi Industries (72) Inventor Hiroshi Yamazaki             4-13 Nakagawa Adachi-ku, Tokyo Stock Exchange             Inside Hitachi Industries F-term (reference) 3H033 AA01 BB01 BB06 CC01 DD19                       DD25 EE11

Claims (4)

[Claims] 1. A method for manufacturing an impeller having a plurality of blades between an upper shroud and a lower shroud, by forming two arcuate grooves separated from each other on a side plate side portion on the blade side of the upper shroud. Form a plating layer in advance on the joint surface between the blade-shaped protrusion formed between the blade and the blade integrally molded on the lower shroud, and abut the nuclear plating layers to perform liquid phase diffusion bonding on both joint surfaces. A method for manufacturing an impeller characterized by. 2. A method of manufacturing an impeller having a plurality of blades between an upper shroud and a lower shroud, by forming two arcuate grooves spaced apart from each other on a side plate side of the lower shroud on the blade side. Form a plating layer in advance on the joint surface between the blade-shaped protrusions formed between the blades and the blade integrally molded on the upper shroud, and abut the nuclear plating layers to perform liquid phase diffusion bonding on both joint surfaces. A method for manufacturing an impeller characterized by. 3. A blade according to claim 1, wherein the joint surface is formed to have a surface roughness of 3 μm or less (0.5 to 3.0 μm), and a plating layer is previously formed on the nuclear joint surface. How to make a car. 4. The method for manufacturing an impeller according to claim 1, wherein the blade portion is inclined.