JPH05202701A - Joining method - Google Patents

Abstract

PURPOSE:To reduce stress concentration factor on a joining surface so as to obtain sufficient strength by forming a fillet on the corner part of the joining surface by means of brazing in a vacuum state, in a joining method in which vacuum diffusion welding is carried out, and diffusion joining is carried out on a residual recessed part in a high temperature hydrostat ic pressure condition. CONSTITUTION:After carrying out the vacuum diffusion welding and high temperature hydrostatic pressure treatment, a fillet 18 is formed so as to eliminate any notch while using wax member 17 on the corner part of a joining surface in a vacuum state. Namely, the corner part of the joining surface is degreased, and the wax member 17 is attached temporarily and set by bond on the corner part of the joining surface. The temperature of an impeller is raised while maintaining vacuum condition in a vacuum furnace, and the specified temperature of the impeller is maintained to weld the impeller. After that, the temperature of the impeller is lowered, and vacuum condition is maintained until the specified temperature is set. When the impeller is heated in the vacuum furnace, flux in the wax member 17 acts on oxide film generated on the base metal of the impeller so as to generate a material having a low fusing point. Furthermore, when the impeller is more heated, the material dissolves to form a metal surface on the surface thereof. The metal surface comes in contact with the wax member 17 so as to generate moisture, and thereby, the fillet 18 is formed by surface tension.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining method applied to, for example, manufacturing an impeller in a centrifugal compressor or a blower.

[0002]

2. Description of the Related Art FIG. 3 is an explanatory view of a conventional joining method by diffusion welding used for manufacturing an impeller in a centrifugal compressor. In the figure, the impeller is composed of a disc-shaped main plate 11, side plates 12, and vanes 13, and the vanes 13 are formed by cutting the side plate 12 integrally with the side plate 12. Protrusions 14 are provided at the tips of the blades 13 so as to surround the entire circumference of the surface joined to the main plate 11 by machining or the like.

The side plate 12 and the main plate 11 on which the blades 13 are formed are overlapped with each other as shown in FIG.
4 are joined by vacuum diffusion welding at high temperature. This protrusion 1
No. 4 has a very small contact area to prevent tipping due to the load during vacuum diffusion welding, and since the load can be small, the blade 13 is a high-performance three-dimensional blade inclined with respect to the main plate 11 and the side plate 12. Is also effective. In the case of an impeller in which the blades 13 are not tilted, the projections 14 may not be provided, and the entire bonding surface may be brought into contact and bonded by vacuum diffusion welding. In this way, the vacuum space 15 remains inside the joint surface. Next, when a high hydrostatic pressure is applied in a high temperature state as shown in FIG.
The stress that causes deformation does not occur based on the principle of hydrostatic pressure, but the vacuum space 15 remaining inside the joint surface is subjected to internal pressure in the direction of being crushed and the remaining joint surface is also diffusion-bonded.
The blade 13 and the main plate 11 are integrated. After that, a heat treatment suitable for the material is performed to secure a predetermined strength, and a final finishing process is performed.

[0004]

In the conventional joining method by diffusion welding as described above, as shown in FIG. 3 (c), the corner portion of the joining surface between the blade 13 and the main plate 11 becomes an edge as it is. However, the notch 16 slightly remains during the vacuum diffusion welding. For this reason, the stress concentration factor at the joint surface becomes large, causing vibration and reduction in strength of the impeller.

[0005]

The joining method according to the present invention is intended to solve the above-mentioned problems, and continuous projections are provided around the periphery of the joining surface so that the joining surfaces abut each other and first In contrast, in the joining method of performing vacuum diffusion welding and then performing diffusion joining to the remaining recesses in high temperature and hydrostatic pressure, a fillet is formed by brazing to the corner portion of the joining surface in vacuum. To do.

Further, the joining method according to the present invention is characterized in that in the above joining method, vacuum diffusion welding is performed, and at the same time, a fillet is formed by brazing at a corner portion of the joining surface in vacuum.

[0007]

That is, in the joining method according to the present invention, continuous protrusions are provided around the periphery of the joint surface, and the joint surfaces are brought into contact with each other, vacuum diffusion welding is performed on the protrusions first, and then the high pressure hydrostatic pressure is applied. In the joining method of performing diffusion joining with respect to the remaining recessed portion, the fillet is formed in the corner portion of the joined surface by brazing in a vacuum, and the brazing material in the corner portion of the joined surface and the recessed portion of the joined surface. Since a vacuum is drawn, a fillet is formed at the corner portion of the joint surface by brazing without generating voids and no notch is left.

In the joining method according to the present invention,
In the above joining method, vacuum diffusion welding is performed and at the same time fillets are formed by brazing at the corners of the joining surface in vacuum. Since the concave portion of the surface is evacuated to a vacuum, a fillet is formed in the corner portion of the joint surface by brazing without generating voids and no notch is left.

[0009]

1 and 2 are explanatory views of a method for joining impellers according to an embodiment of the present invention. In the figure, the method for joining impellers according to the present embodiment is used for manufacturing an impeller in a centrifugal compressor, and the impeller has a disc-shaped main plate 11 and side plates 12 as shown in FIG. The blade 13 is formed by being machined from the material of the side plate 12 integrally with the side plate 12 and machined by machining as shown in FIG. Protrusions 14 are provided at the tips of the blades 13 so as to surround the entire circumference of the surface joined to the main plate 11 by machining or the like, as shown in FIGS.

As shown in FIG. 2 (a), the side plate 12 and the main plate 11 on which the blades 13 are formed are overlapped with each other and a load is applied from the outside, so that the projections 1 on the entire circumference of the joint surface of the blades 13 are formed.
4 are joined by vacuum diffusion welding at high temperature. This protrusion 1
No. 4 has a very small contact area in order to prevent tilting due to a load during vacuum diffusion welding, and since the load may be small, a high-performance three-dimensional blade in which the blade 13 is inclined with respect to the main plate 11 and the side plate 12 Is also effective. In the case of an impeller in which the blades 13 are not inclined, the entire bonding surface may be contacted and vacuum diffusion welding may be performed without providing the protrusions 14. In this way, the vacuum space 15 remains inside the joint surface. Next, when a high hydrostatic pressure is applied in a high temperature state as shown in FIG.
The stress that causes deformation does not occur based on the principle of hydrostatic pressure, but the vacuum space 15 remaining inside the joint surface is subjected to internal pressure in the direction of being crushed and the remaining joint surface is also diffusion-bonded.
The blade 13 and the main plate 11 are integrated.

According to such a joining method by diffusion welding, the wing is
The corner portion of the joint surface between the root 13 and the main plate 11 remains as it is.
And a slight notch remains during vacuum diffusion welding.
However, this joining method uses vacuum diffusion welding and high temperature hydrostatic pressure treatment.
Then, the brazing material 17 is further applied to the corners of the joint surface in a vacuum.
To form the fillet and eliminate the notch
is doing. That is, as shown in FIG.
The grease is degreased with acetone, and the Ni powder and binder (W
And a mixture of
And extrude the rod-shaped brazing filler metal 17 having a diameter of 1 to 2 mm.
To manufacture. Then, the brazing material 17 is applied to the corner portion of the joint surface.
Temporarily attach with a bond (Ni rosin) and set. So
Then, set the impeller in the vacuum furnace and^-3Key to Torr
Temperature is raised at 150 to 200 ° C./Hr while operating at 1050
Keep at 1 ° C for 1 hour. Brazed in this way
After that, the temperature is lowered at a rate of 100 ° C./Hr until 200 ° C.
10 ^-3Keep Torr. Heating the impeller in a vacuum furnace
When going, the oxide film formed on the base material of the impeller is in the brazing material 17.
The flux acts to produce a substance with a low melting point. This thing
When the quality is further heated, it melts and forms a metal surface on the surface of the impeller.
To achieve. The metal surface and the brazing filler metal 17 come into contact with each other to cause wetting.
Then, the fillet 18 is formed by the surface tension. Brazing material
17 and the space 15 generated inside the joint surface are evacuated to a vacuum.
As shown in Fig. 4 (d), no void is generated.
Make a clean fillet 18 and leave a notch as shown.
I don't. After that, heat treatment suitable for the material
Ensure strength and perform final finishing.

In the case of only vacuum diffusion welding and high temperature hydrostatic pressure treatment, notches remain at the corners of the joint surface after joining,
In the present joining method, the fillet 18 is formed by brazing as described above, so that no notch remains and the stress concentration factor becomes small, so that the impeller has sufficient strength against fatigue. Fillet 18 by brazing
Even if the formation is carried out at the same time as the vacuum diffusion welding, the same effects as those of the joining method according to the above-mentioned embodiment can be obtained. Moreover, these joining methods can be used for various joining other than manufacture of an impeller.

[0013]

The joining method according to the present invention is performed as described above, and since the fillet is formed at the corner portion of the joining surface and no notch is left, the stress concentration factor at the joining surface becomes small and sufficient strength is obtained. Is obtained.

[Brief description of drawings]

FIG. 1 (a) is a sectional view of an impeller in a method for joining impellers according to an embodiment of the present invention, and FIGS. 1 (b) and 1 (c).
Is a perspective view of the blade, and FIG. 7D is d- in FIG.
It is d sectional drawing.

FIG. 2 is an explanatory diagram of a method for joining the impellers.

FIG. 3 is an explanatory diagram of a conventional method for joining impellers.

[Explanation of symbols]

 11 Main Plate 12 Side Plate 13 Blade 14 Protrusion 15 Space 17 Brazing Material 18 Fillet

Claims (2)

[Claims] 1. A continuous projection is provided around the periphery of the joint surface to bring the joint surfaces into contact with each other, and first, the diffusion diffusion welding is performed on the protrusions, and then the residual diffusion portion is diffused during high temperature hydrostatic pressure. A joining method for joining, further comprising forming a fillet by brazing at a corner portion of the joining surface in a vacuum. 2. The joining method according to claim 1, wherein the fillet is formed by brazing the corner portion of the joining surface in vacuum while performing the vacuum diffusion welding on the protrusion.