JPH1147955A - Manufacturing method of composite structure disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method in which the strength of a joining part of a composite structural disk taking respective advantages of a forging material and a casting material is made roughly equal to those of respective base materials. SOLUTION: In the composite structural disk production method, in which the inner peripheral face of an annular outside disk made of a casting material and an outer peripheral face of an inside disk made of a forging material are joined by diffusion joining, the diffusion joining is conducted by heating to about 950 deg.C in vacuum and applying a joining face pressure of about 50-55 MPa for about 1 hr, successively after heated at about 720 deg.C for about 8 hr, it is heat treated at about 620 deg.C for about 10 hr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to gears used in turbines, jet engines and the like, and to disks such as impellers having blades attached to the outer periphery of the disks, and more particularly to joining these disks by casting and forging. The present invention relates to a method of manufacturing a composite structure disk to be constituted.

[0002]

2. Description of the Related Art Gears and impellers are often used in gas turbines and jet engines for aircraft. As shown in FIG. 1, the rim portion 1 on the outer periphery of the disk is provided with teeth and blades constituting a gear, and includes a bore portion 3 connected to a rotating shaft and a web portion 2 connecting the bore portion 3 and the rim portion 1. It is configured. These gears and impellers are used under severe conditions of rotating at high speed in a high temperature state and receiving a high load.

[0003] Conventionally, these gears and impellers have been integrally made of a forged material or a cast material. Since the outside of the rim portion 1 has a complicated shape such as a tooth or a blade implant portion, a disk is made of a forged material and machined or the whole is formed of a cast material. From the viewpoint of strength, the rim portion 1 is required to have high fatigue strength at a high temperature, and the web portion 2 and the bore portion 3 are required to have creep strength.

[0004]

Conventionally, in order to satisfy the requirements of the creep strength of the web portion 2 and the bore portion 3, it has been often the case that the rim portion 1 is made of a forged material and the complicated shape of the rim portion 1 is machined. When the rim 1 is made of a cast material in order to facilitate the manufacture, the web 2 and the bore 3 are used where the creep strength is not required. For this reason, the advantage of the forged material having high creep strength was offset by the disadvantage of machining. Further, the cast material has an advantage that it is suitable for manufacturing a product having a complicated shape and has a high fatigue strength required for the rim portion 1, but is offset by a drawback that the creep strength is not large. To eliminate such disadvantages,
In Japanese Patent Application Laid-Open No. 7-208103, the present applicant has proposed a composite structure disk in which the inner peripheral surface of a ring-shaped outer disk made of a cast material and the outer peripheral surface of an inner disk made of a forged material are joined by diffusion bonding. However, since the joining method shown in this proposal was developed assuming that only 70% of the cast material having the weaker joint portion is required, the strength is lower than the base material strength.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and provides a method of manufacturing a joint portion of a composite structure disk that makes use of the respective advantages of a forged material and a cast material so that the strength of the joint is substantially the same as the strength of the base material. The purpose is to provide.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, the inner peripheral surface of a ring-shaped outer disk made of a cast material and the outer peripheral surface of an inner disk made of a forged material are diffusion bonded. In the method of manufacturing a composite structure disc, the diffusion bonding is performed by heating to about 950 ° C. in a vacuum state, maintaining the pressure at the bonding surface at about 50 to 55 MPa, and holding for about 1 hour, and then heating at about 720 ° C. for about 8 hours. After that, heat treatment is performed at about 620 ° C. for about 10 hours.

At approximately 950 ° C. and approximately 50 to 55 MPa, 1
After performing the time diffusion bonding process, approximately 7
A solution treatment is performed at 20 ° C. for 8 hours, and then an aging treatment is performed at approximately 620 ° C. for 10 hours, so that the influence of heat and stress on the base material due to the diffusion bonding process is removed by a post heat treatment. It is possible to prevent a decrease in the strength of the joint, and make the strength of the joint substantially the same as the strength of the base material.

According to the second aspect of the present invention, a titanium alloy foil is placed around the outer disk to prevent oxidation of the joint surface.

By arranging the titanium foil around the outer disk, the deoxidizing action of titanium works under vacuum and high temperature conditions to prevent oxidation of the joint surface and prevent the joint surface from decreasing in strength.

According to a third aspect of the present invention, in the method of manufacturing a composite structure disk, the inner peripheral surface of the ring-shaped outer disk made of a cast material and the outer peripheral surface of the inner disk made of a forged material are joined by diffusion bonding. Surface and outer surface roughness
a 0.3 μm or less.

When the roughness of the joining surface is reduced, the joining pressure can be uniformly applied to the joining surface, the joining is stabilized, the variation in the joining strength is reduced, and the decrease in the joining strength is prevented.

According to a fourth aspect of the present invention, in the method of manufacturing a composite structure disk, the inner peripheral surface of the ring-shaped outer disk made of a cast material and the outer peripheral surface of the inner disk made of a forged material are joined by diffusion bonding. The inner peripheral surface of is inclined at a predetermined angle with respect to the rotation axis of the composite structure disc,
The outer peripheral surface of the inner disk is also inclined at the predetermined angle with respect to the rotation axis, and has a thickness substantially equal to the step between the inner disk and the outer disk before joining, at least from the outside of the upper and lower surfaces of the joined disks. It is removed in a range including the joining surface.

[0013] Before pressing on the joint surface, it is not in contact with the mating surface,
The portions near the upper surface and the lower surface of the joined portion that is joined by pressurization are where the oxide layer is likely to exist. If there is an oxide layer, diffusion bonding is not sufficiently performed, and the strength of the bonded portion is reduced. Therefore, by removing such a portion, it is possible to prevent a decrease in the strength of the joint.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a disk having a composite structure according to the present embodiment, wherein (a) shows a gear (b) and an impeller. These are used as high performance disks for cogeneration gas turbines and aircraft jet engines. In both cases (a) and (b), the rim 1 is made of a cast material, which facilitates the production of complicated shapes for the teeth and the implanted portions of the blades 5. The web part 2 and the bore part 3 are integrally manufactured by a forging material, and the joint part 4 is joined by diffusion bonding, and the outer peripheral surface of the web part 2 and the inner peripheral surface of the rim part 1 are joined.

FIG. 2 is a schematic diagram of the joining process. This apparatus is provided in a vacuum furnace. A rim-side preform 1a is placed on the jig, and an opening having an inclination of an angle θ from a horizontal plane provided inside the rim-side preform 1a,
The bore-side preform 2a is fitted. The outer peripheral surface of the bore-side preform 2a is also inclined at an angle θ from the horizontal plane.
The rim-side preform 1a and the bore-side preform 2a have the same thickness, but before pressing, as shown in FIG.
Only the bore-side preform 2a is raised, and h is the compression allowance. The preform indicates a shape before being processed into a final shape as shown in FIG. 1 and is processed into a final shape after joining. The rim-side preform 1a is made of nickel-Ni cast material IN100, and the bore-side preform 2a is made of Ni.
The case where the forging material INCO718 of the system is used is shown. The materials of the cast material and the forged material are merely examples. In addition,
A degassing groove is provided on the lower surface of the rim-side preform 1a so as to release gas trapped between the lower surface of the bore-side preform 2a and the jig when pressurized. Further, the outside of the rim-side preform 1a is surrounded by titanium Ti foil, and performs a deoxidizing action at the time of diffusion bonding to prevent the bonding surface 6 from being oxidized.

FIG. 3 is a time chart of the diffusion process.
The degree of vacuum in the vacuum furnace is kept at 1 × 10 ⁻⁵ mmHg or less.
First, the furnace is heated to heat the material to be processed comprising the rim-side preform 1a and the bore-side preform 2a to 950 ° C., and a vertical load is applied to the bore-side preform 2a while maintaining this temperature. The vertical load is the pressure perpendicular to the joint surface 6 of 50 to 5
It is set to 5 MPa. Due to this load, the bore-side preform 2a is pushed in, h of the lower surface side becomes zero, and the lower surfaces of the bore-side preform 2a and the rim-side preform 1a become the same surface. After maintaining this state for one hour, a heat treatment is performed after bonding. In the post-joining heat treatment, a solution treatment is performed at 720 ° C. for 8 hours, followed by an aging treatment at 620 ° C. for 10 hours. As for the shape of the jig, the lower surface of the bore-side preform 2a is connected to the rim-side preform 1a.
Can be protruded from the lower surface of the.

After the completion of the diffusion process, mechanical processing is performed to finish the shape shown in FIG. In this machining,
The design dimensions are determined so that the range of h of the joint surface 6 shown in FIG. 2 can be removed. FIG. 4 is a view showing removal of an oxide film generating portion on the bonding surface, and a hatched area having a depth h is removed from upper and lower surfaces where an oxide film may be generated.
Since the portion of the bonding surface 6 where the oxide film is easily generated is deleted as described above, the same bonding strength as that of the base material can be obtained. The joining is performed in a finished state such that the roughness of the joining surface 6 is Ra 0.3 μm or less. By reducing the roughness of the bonding surface 6 in this manner, the bonding surface 6 is uniformly pressurized, and the strength of the bonding surface 6 becomes uniform.

FIG. 5 shows the temperature and strength of the turbine disk manufactured as described above. In the upper part of the figure, a schematic diagram of a cross section of the turbine disk is shown. There is a bore 3 and a web 2 from the axis center line C, and the rim 1
Is connected. Bore part 3 and web part 2 are forged material IN
The rim 1 is made of a cast material IN100. The temperature of the turbine disk changes depending on the distance from the central axis C. The bold line in the drawing indicates the temperature of the joining material (referred to as BAS material) at a position from the axial center line C and the tensile strength of the BAS material at that temperature. The temperature distribution at the position from the axis center line C is not a simple primary distribution as shown in the figure, but such a distribution is assumed for ease of explanation. The strength from the axis center line C to the joint is the base metal strength of the forged material INCO718, and the joint 4 has both members (INC
O718 and IN100) and the strength of the joint 4 match. The strength before the joint 4 is the cast material IN100.
Of strength.

[0019]

As is apparent from the above description, according to the present invention, a composite structure disk is formed by using a casting material for the outer disk and a forging material for the inner disk, and heat and stress due to diffusion bonding are applied to the base material. By removing the influence by the post heat treatment, it is possible to prevent the strength of the base material and the joint from lowering, and to make the strength of the joint substantially equal to the strength of the base material. Furthermore, the oxidation of the bonding surface is prevented by using a titanium foil to make the inside of the furnace a deoxidizing atmosphere. In addition, by reducing the roughness of the joint surface, the joint surface is uniformly pressed and uniform joining strength can be obtained. Further, by removing the oxide film generating portion at the end of the bonding surface, the bonding surface can be made sound. By these processes, the strength of the joint surface can be made equal to the strength of the base material.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of the present invention, where (a) is a gear,
(B) shows an impeller.

FIG. 2 is a schematic diagram of a joining process.

FIG. 3 is a time chart of a diffusion process.

FIG. 4 is an explanatory view for removing oxide film forming portions at both ends of a bonding surface.

FIG. 5 is a diagram showing an example of a tensile strength distribution at each position of a joining material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rim part (outer disk) 1a Rim side preform 2 Web part (inner disk) 2a Bore side preform 3 Bore part (inner disk) 4 Joint part 5 Blade 6 Joint surface

Claims (4)

[Claims] In a method of manufacturing a composite structure disk in which an inner peripheral surface of a ring-shaped outer disk made of a cast material and an outer peripheral surface of an inner disk made of a forged material are joined by diffusion bonding, a temperature of about 950 ° C. is applied in a vacuum state. Diffusion bonding is performed by heating and maintaining the pressure of the bonding surface at approximately 50 to 55 MPa for approximately 1 hour, and then heating at approximately 720 ° C. for approximately 8 hours.
A method for manufacturing a disk having a composite structure, comprising performing heat treatment at about 620 ° C. for about 10 hours. 2. A composite structure disk manufacturing method according to claim 1, wherein a titanium alloy foil is placed around the outer disk to prevent oxidation of a joint surface. 3. A method for manufacturing a composite structure disk in which an inner peripheral surface of a ring-shaped outer disk made of a casting material and an outer peripheral surface of an inner disk made of a forged material are joined by diffusion bonding. A composite structure disc manufacturing method characterized in that the roughness is set to Ra 0.3 μ or less. 4. A composite structure disc manufacturing method in which an inner peripheral surface of a ring-shaped outer disk made of a cast material and an outer peripheral surface of an inner disk made of a forged material are joined by diffusion bonding. It is inclined at a predetermined angle with respect to the rotation axis of the composite structure disk, and the outer peripheral surface of the inner disk is also inclined with the predetermined angle with respect to the rotation axis,
A composite structure disk manufacturing method, characterized in that a thickness substantially equal to a step between an inner disk and an outer disk before joining is removed from outside of upper and lower surfaces of the joined disk at least including a joining surface.