JP2737413B2 - Ceramic ball joint and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic ball joint and a method for manufacturing the same.

[0002]

2. Description of the Related Art Ceramics having excellent heat resistance are used in, for example, gas turbines and other high-temperature parts. As a connection structure that allows relative displacement between ceramic components below, a ceramic ball joint that supports a tensile force of a spring or the like so as to be capable of angular displacement is required.

As a conventional ceramic ball joint, for example, as disclosed in Japanese Utility Model Application Laid-Open No. 62-162416, a spherical portion protruding in a spherical shape is formed at one end of a male rod by ceramic, and this spherical portion is slid. 2. Description of the Related Art There is known a structure in which a female rod having a fitting hole to be included therein is formed of metal.

However, when the female rod is to be formed of ceramic, since the ceramic cannot be plastically processed like a metal material, the portion of the drawing surface of the fitting hole receiving the tensile force is formed by combining a plurality of ceramic parts. Formed, resulting in a complicated structure.

The present invention has been made in view of the above problems, and has as its object to simplify the structure of a ceramic ball joint capable of supporting a tensile force.

[0006]

According to the present invention, a spherical portion protruding in a spherical shape is integrally formed at one end of a male rod with ceramic, and the spherical portion is fitted into a fitting hole at one end of a female rod integrally formed with ceramic. Is slidably contained, and the female rod is formed so that the opening diameter of the fitting hole before sintering is larger than the outer diameter of the sintered sphere portion and smaller after sintering.

The second invention is a method of manufacturing a ceramic ball joint, in which the female rod has a fitting hole whose opening diameter is larger than the outer diameter of the sintered spherical portion and smaller after sintering. Then, the female rod is sintered in such a state that the sintered sphere is fitted inside the fitting hole.

[0008]

[Action] By forming the opening diameter of the fitting hole smaller than the outer diameter of the ball portion, the ball portion does not fall out of the fitting hole, and the male rod and the female rod angularly displace the tensile force suspended between them. A ceramic ball joint that supports as much as possible is constructed.

As a method of manufacturing the female rod, the female rod is sintered in a state in which the sintered spherical portion is fitted in the fitting hole. The diameter can be reduced to be smaller than the outer diameter of the bulb.

On the other hand, in the method of sintering the male rod and the female rod in a state of being separated from each other, the female rod cannot be fitted into the spherical part in the fitted hole after sintering. The aperture portion must be formed separately, resulting in a complicated structure.

[0011]

FIG. 1 shows an embodiment of the present invention. This ball joint 1 comprises a ceramic male rod 2 and a ceramic female rod 12 which are connected to each other so as to be angularly displaceable. Is used for a support structure that connects

The male rod 2 has a spherical portion 3 protruding spherically from one end thereof, and a flange portion 4 fixed to a gas turbine casing (supported member) at the other end, and these portions are integrally formed of ceramic. Is done.

At one end of the female rod 12, a fitting hole 13 containing the ball portion 3 of the male rod 2 is opened, and the opening diameter d of the fitting hole 13 is narrowed to be smaller than the outer diameter c of the ball portion 3. These parts are integrally formed of ceramic. This allows
The inner wall surface of the fitting hole 13 has a stop surface 13a that slides on the back surface 3a side of the spherical portion 3, and a portion forming the stop surface 13a is also integrally formed of ceramic by a manufacturing method of the present invention described later. As the ceramic material, for example, silicon nitride, silicon carbide or the like is used.

A groove 14 is formed in the middle of the female rod 12, a washer is fitted in the groove 14, and a coil spring seated on the washer is interposed between shrouds (supported members) of the gas turbine. . The shroud is pressed and connected to the casing via the ball joint 1 by the elastic restoring force of the coil spring.

Next, a method of manufacturing the ceramic ball joint 1 will be described.

As shown in FIGS. 2 and 3, before the sintering, the opening diameter D of the fitting hole 13 of the female rod 12 is formed to be larger than the outer diameter c of the sintered spherical portion 3. , Fitting hole 13
To insert the sphere 3 into the hole.

As shown in FIG. 4, the sintering of the female rod 12 is performed in a state where the sintered ball portion 3 is fitted in the fitting hole 13. During the sintering, the ceramic material shrinks at a predetermined ratio, so that the opening diameter d of the fitting hole 13 after sintering is reduced to the spherical portion
Smaller than the outer diameter c. That is, the dimensional relationship is d <c <D.

The inner diameter B of the fitting hole 13 before sintering is formed at a predetermined ratio larger than the outer diameter c of the sintered spherical portion 3.
The clearance between the sintered ball 3 and the fitting hole 13 is α,
Assuming that the shrinkage ratio during sintering of the ceramic material is γ, the inner diameter B of the fitting hole 13 can be obtained by the following equation. B = (c + α) / γ The shrinkage ratio γ varies depending on ceramic materials such as silicon nitride and silicon carbide, or depending on the sintering aid, sintering temperature, etc., but is generally in the range of 0.7 <γ <0.8. Becomes The clearance α is c · 1/1000 <α <c · 3/1000
And the ball portion 3 can slide freely with respect to the fitting hole 13.

As described above, by sintering the female rod 12 in a state where the sintered ball portion 3 is fitted in the fitting hole 13, the opening diameter d of the fitted hole 13 after sintering is reduced. By contracting the outer diameter c of the spherical portion 3 smaller than the outer diameter c, it is possible to integrally form the diaphragm surface 13a of the fitting hole 13 that includes the spherical portion 3 in the female rod 12 with ceramic.

On the other hand, in the method of sintering the male rod and the female rod separately from each other, it is impossible to fit the ball into the fitting hole after sintering. The portion of the hole 13 where the aperture surface 13a is formed must be formed separately from the female rod 12, resulting in a complicated structure.

In the ball joint 1, the ball portion 3 is prevented from coming off through the throttle surface 13 a of the fitting hole 13, and the female rod 1
It supports the tensile force acting between the male rod 2 and the male rod 2 so as to be angularly displaceable. Therefore, due to the operation of the gas turbine, the thermal expansion difference and uneven thermal distortion generated between the casing and the shroud are absorbed by bending the male rod 2 and the female rod 12 with each other while compressing the coil spring, It is possible to prevent local stress from being generated in each supported member of the gas turbine and each ceramic material of the male rod 2 and the female rod 12. Of course, since the male rod 2 and the female rod 12 are formed of ceramic, sufficient heat resistance is secured.

Next, in another embodiment shown in FIG. 5, one female rod 31 is provided between the first male rod 21 and the second male rod 41.
Are provided with two ceramic ball joints 20 and 30 to enable the first male rod 21 and the second male rod 41 to move in parallel with each other while angularly displacing the male rod 31 as shown in FIG. It is.

The female rod 31 has a first male rod 2 at one end.
It has a fitting hole 32 containing one ball portion 22 and a fitting hole 33 containing the ball portion 42 of the second male rod 41 at the other end.

The first male rod 21 has a flange portion 23 at the other end, and the flange portion 23 is fixed to a gas turbine casing (not shown). On the other hand, the second male rod 41 is formed in a rod shape, and a groove 43 is formed in the middle thereof. A washer is fitted into the groove 43, and a coil spring seated on the washer is interposed between the shrouds of the gas turbine, and the shroud is pressed against the casing by the elastic restoring force of the coil spring.

As shown in FIG. 6, the difference in thermal expansion and uneven thermal strain generated between the casing and the shroud due to the operation of the gas turbine compresses the coil spring, as shown in FIG.
By bending the female rod 31 with respect to the first male rod 21 and the second male rod 41, the first male rod 21 and the second male rod 41 can move parallel to each other by an eccentric amount L. Bending stress can be prevented from being generated in 21, 31, and 41. Of course, each rod 21, 31, 4
1 is made of a ceramic material, so that sufficient heat resistance is secured.

FIG. 7 shows a state of the female rod 31 at the time of sintering. The spherical part 22 of the first male rod 21 and the spherical part 42 of the second male rod 41 which have been sintered and finished in a predetermined shape are combined. , Each fitting hole 32,3 formed in anticipation of the shrinkage ratio after sintering
3 is performed. Due to the shrinkage at the time of sintering, each of the fitting holes 32 and 33 includes the sphere portion 22 of the first male rod 21 and the sphere portion 42 of the second male rod 41 with a predetermined clearance. Adjust the opening diameter to each sphere 22,4.
2 outside diameter.

[0027]

As described above, according to the present invention, the spherical portion protruding spherically is formed at one end of the male rod integrally with ceramic while the ball is inserted into the fitting hole at one end of the female rod integrally formed with ceramic. Part was slidably included, and the opening diameter of the fitting hole before sintering of the female rod was formed to be larger than the outer diameter of the sintered sphere part and smaller after sintering, A ceramic ball joint that supports a tensile force suspended between a male rod and a female rod so as to be angularly displaceable can be provided.

According to a second aspect of the present invention, as a method of manufacturing a ceramic ball joint, a female rod is formed so that an opening diameter of a fitting hole thereof is larger than an outer diameter of a sintered spherical portion. Since the sintering is performed in a state where the sintered ball portion is fitted inside the fitting hole, the opening of the fitting hole is narrowed to be smaller than the outer diameter of the ball portion due to the contraction action of the ceramic material generated at the time of sintering. be able to. Thereby, the female rod can be integrated, the number of parts can be reduced, and the structure can be simplified.

[Brief description of the drawings]

FIG. 1 is a sectional view of a ball joint showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the female rod before sintering.

FIG. 3 is a sectional view of a male rod before sintering.

FIG. 4 is a sectional view of the ball joint before sintering.

FIG. 5 is a sectional view of a ball joint showing another embodiment.

FIG. 6 is a sectional view showing the movement of the ball joint.

FIG. 7 is a sectional view of the ball joint before sintering.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ball joint 2 Male rod 3 Ball part 12 Female rod 13 Fitting hole 13a Drawing surface

Claims (2)

(57) [Claims] 1. A spherical portion protruding in a spherical shape is integrally formed at one end of a male rod with ceramic, and the spherical portion is slidably included in a fitting hole at one end of a female rod integrally formed of ceramic. A ceramic ball joint characterized in that a female rod is formed such that an opening diameter of a fitting hole before sintering is larger than an outer diameter of a sintered sphere portion and smaller after sintering. 2. The female rod is shaped so that the opening diameter of the fitting hole is larger than the outer diameter of the sintered spherical portion and smaller after sintering. A method of manufacturing a ceramic ball joint, which is performed in a state where a sintered spherical portion is fitted inside the fitting hole.