JP2553672Y2 - Ceramic spherical plain bearings - 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 spherical plain bearing.

[0002]

2. Description of the Related Art Spherical plain bearings of this type are often used as bearings in the swinging parts of various machines. As a typical example of this structure, conventionally, both an inner race and an outer race are used, for example. In order to fit the inner race and the outer race, the outer race is formed with a groove for inserting the inner race at one end of the inner circumference, or the inner race or the outer race is formed of a metal material such as M50. Has a structure in which either one of the two is divided into two in a radially-half manner.

[0003]

Although such metal spherical plain bearings have a seizure life assumed in normal use, when they are used in a swinging part of a machine in a high-temperature environment, The sliding surface of the sliding bearing may have an unexpectedly high temperature that significantly shortens the expected life.

[0004] For such high temperatures, it is conceivable to use a device for cooling or lubricating the sliding surface so as to extend the life of the sliding surface. However, the cost as a bearing increases, and as a result, there is a possibility that the device may not be used, which may lead to inconvenience.

[0005] In view of the above, the inventors of the present invention have made the lace material ceramic instead of the conventional metal so that the life of seizure on the slip surface can be extended without increasing the cost. While proposing that
We are diligently studying the practical use of the ceramic spherical plain bearing.

By the way, in the course of this research, the inner race and the outer race are attached to the other party (the swing shaft and the bearing housing).
In the case of fixing with metal, it was performed by press-fitting similarly to the case of metal, but it was found that the following problems occurred due to this.

That is, if the swing shaft is made of metal, the difference in linear expansion coefficient between the metal and the ceramic inner race is large, so that the swing shaft thermally expands as the temperature rises. The inner race is too small, and the inner race is easily damaged. On the other hand, when the bearing housing is made of metal, there is a large difference in linear expansion coefficient between the bearing housing and the outer race made of ceramics. The fitting gap becomes too large and the supporting state of the swing shaft becomes unstable.

At the time when the temperature rises, even if it is attempted to set a fitting gap in advance so that a fitting state between the mating member and the inner and outer races is preferable, the inner race is kept concentric with the swing shaft at normal temperature. It is conceivable that the operation cannot be performed and the operation at the initial stage of operation becomes unstable, and it is impossible to realize such that the outer race cannot be assembled to the bearing housing.

The present invention has been made to solve such a problem, and it is intended to prevent the inner race made of ceramics from being damaged by thermal expansion of a swing shaft having a larger linear expansion coefficient than ceramics. A second object is to stabilize the support state of the ceramic outer race by thermal expansion of a bearing housing having a larger coefficient of linear expansion than ceramics, and further, to have a larger coefficient of linear expansion than ceramics. The third object is to stabilize the support state of the ceramic outer race while preventing damage to the ceramic inner race when the swing shaft and the bearing housing are thermally expanded when interposed between the swing shaft and the bearing housing. The purpose of.

[0010]

In order to achieve such an object, the present invention is to form a radially outer peripheral surface of a ceramic inner race into a convex or concave shape having a constant radius of curvature, The following configuration is used in a ceramic spherical plain bearing in which a radially inner peripheral surface of a ceramic outer race is similarly formed in a concave or convex shape with a curvature which coincides with or substantially coincides with the curvature in the radial direction.

[0011] In the first ceramic spherical plain bearing of the present invention, the inner race is arranged with a required gap around the outer periphery of a shaft having a larger coefficient of linear expansion than the inner race made of ceramics. Are sandwiched from both sides in the axial direction by two fixing rings attached to the shaft, and each contact surface between the two fixing rings and the inner race is directed to both sides from the center in the axial direction of the inner race. It is characterized in that it is concentrically fixed to the shaft by being formed on a tapered surface having a large diameter.

In the second ceramic spherical plain bearing of the present invention, the outer race is arranged on the inner periphery of a bearing housing having a larger linear expansion coefficient than the outer race made of ceramics, and the outer race is mounted on the bearing housing. While being sandwiched from both sides in the axial direction by the two fixing rings to be mounted, each contact surface between the two fixing rings and the outer race has a large diameter toward both sides from the center in the axial direction of the outer race. It is characterized in that it is formed concentrically on the shaft on which the inner race is mounted by being formed on a tapered surface.

[0013] In the third ceramic spherical plain bearing of the present invention, the inner race is arranged with a required gap around the outer periphery of a shaft having a larger coefficient of linear expansion than the inner race made of ceramics. Are sandwiched from both sides in the axial direction by two fixing rings attached to the shaft, and each contact surface between the two fixing rings and the inner race is directed to both sides from the center in the axial direction of the inner race. The outer race is arranged concentrically on the shaft by being formed on a tapered surface having a large diameter, and the outer race is arranged on the inner periphery of a bearing housing having a larger linear expansion coefficient than the outer race made of ceramics, and The outer race is sandwiched by two fixing rings mounted on the bearing housing from both sides in the axial direction, and each contact surface between the two fixing rings and the outer race is in the axial direction of the outer race. Characterized in that it is coaxially fixed to the shaft by being formed into a tapered surface which becomes large diameter toward the Middle to both sides.

[0014]

In the first ceramic spherical plain bearing, the gap between the inner race and the shaft is sufficiently large so that the inner race is not pressed even if the shaft thermally expands. The inner race is sandwiched between the two fixing rings so that the inner race is concentrically arranged with respect to the shaft even if it is not expanded, and the fixing ring and the inner race are brought into contact with each other with the tapered surfaces. As a result, it is not necessary to control the dimensional accuracy of the respective mating surfaces of the shaft and the inner race with high accuracy, and the manufacture becomes easy. In addition, even if the shaft thermally expands, the inner race is stretched radially outward through the fixing ring, so that the position of the inner race remains concentric with the shaft. In addition, since the tension force applied to the inner race from the thermally expanding fixing ring is applied to the tapered surface of the inner race, stress concentration at the edge of the inner race is reduced. Furthermore, even when a greater tension is applied, if the degree of engagement between the fixing ring and the shaft is adjusted as appropriate, the fixing ring moves to the outside of the bearing along the tapered surface of the inner race, so that the inner ring is moved. The race is not overpowered.

In the second ceramic spherical plain bearing, in short, the outer race is held by the bearing housing via the fixing ring so that the support state of the outer race does not become unstable even if the bearing housing thermally expands. ing. As a result, when the bearing housing thermally expands, the fitting gap with the outer race is increased, but the outer race is pulled radially outward through the fixing ring. And will be kept in a concentric position. Moreover, the tension applied from the fixing ring to the outer race can be effectively released by moving the fixing ring to the outside of the bearing along the tapered surface of the outer race if the degree of fitting between the fixing ring and the housing is adjusted appropriately. , So that unnecessary force is not applied to the outer race.

Furthermore, in the first and second ceramic spherical plain bearings, since the fixing ring and the inner and outer races are in contact with each other on the tapered surfaces, the inner and outer races are attached to the other party (the swing shaft, the bearing). Even if it is swung by the housing), the fixing ring and the inner and outer races come into contact with each other and do not come into contact with the edge, thereby preventing the ceramic inner and outer races from being chipped.

The third ceramic spherical plain bearing can simultaneously exert the functions of the first and second ceramic spherical plain bearings.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIGS. 1 and 2 show a first embodiment of the present invention. In the drawing, 1 is a bearing housing, 2 is a swing shaft inserted into the bearing housing 1, 3A and 3B are swing shafts 2.
A pair of radially split ceramic inner races 4 are arranged on the outer periphery of the bearing so as to form a ring, and the inner race 4 is arranged on the inner periphery of the bearing housing 1 and slides spherically with the inner races 3A and 3B. The annular ceramic outer races 5 and 5 forming a bearing are externally fitted and press fitted to the swing shaft 2 so as to sandwich the inner races 3A and 3B, which are combined in an annular shape, on the outer periphery of the swing shaft 2 from both sides thereof. Two pairs of fixing rings.

In this embodiment, the bearing housing 1 is made of a material that approximates the linear expansion coefficient of the outer race 4 made of ceramics, and the swing shaft 2 is made of metal such as SUS304.

The radially outer peripheral surface of each of the inner races 3A and 3B has a radially convex spherical shape having a constant curvature, and the radially inner peripheral surface of the outer race 4 has the inner races 3A and 3B.
Are formed in a radially concave spherical shape having a curvature which coincides with or substantially coincides with the outer peripheral surface thereof. The inner races 3 </ b> A and 3 </ b> B are fitted to the outer race 4 in a state having a predetermined minute gap, and are fitted to the swing shaft 2 with a sufficiently large fitting gap. Further, each of the two inner races 3A, 3B is formed with tapered surfaces 6A, 6B that increase in diameter from near the center in the axial direction toward the end surfaces on both axial sides of the inner peripheral surface. 6A,
The angle 6B is formed in a curved shape to avoid stress concentration. When the inner races 3A and 3B and the outer race 4 are made of ceramics, a mixture of ceramic powder (silicon nitride) and a rare earth element as a sintering aid is first used. Then, this molded product is HP (hot pressed), HIP
(Hot isostatic press) and CIP (cold isostatic press).

Each of the fixing rings 5 and 5 has an axial through hole (symbol omitted) of a size that can be externally fitted and press-fitted into the swing shaft 2 by appropriate fitting, and also from the center in the axial direction. On the other hand, tapered surfaces 7, 7 having a smaller diameter toward the end surface side are formed. When the fixing rings 5 and 5 are externally fitted and pressed into the swing shaft 2, the tapered surfaces 7 and 7 are fixed to the swing shaft 2.
Inner races 3A and 3B combined in an annular shape around the outer circumference
Pressure contact is made corresponding to each of the tapered surfaces 6A and 6B.
The fixing rings 5 and 5 are made of the same metal as the swing shaft 2 or a material having a similar linear expansion coefficient.

Next, the operation will be described. Since the fitting gap between the oscillating shaft 2 and the inner races 3A and 3B is set to be sufficiently large in advance, even if the oscillating shaft 2 thermally expands due to a rise in temperature, the inner races 3A and 3B will not move. No excessive force is applied. By the way, together with the swing shaft 2, the fixing rings 5, 5
Is thermally expanded, so that the inner races 3A, 3B are pressed so as to be pressed against the outer race 4 side, so that the inner races 3A, 3B are maintained at the concentric position with the swing shaft 2. Become. Further, since the inner races 3A and 3B are in a half-split shape, the thermal expansion of the fixing rings 5 and 5 is absorbed by the split surface merely by increasing the diameter, so that no excessive force is applied to the inner races 3A and 3B. . Furthermore, even if the inner races 3A, 3B become larger in diameter than the gap between the inner and outer races 3A, 3B, 4, the inner race 3
Since stress is applied to the tapered surfaces 6A and 6B of A and 3B, stress concentration at the edge can be avoided. Furthermore, when a stress greater than that is applied, the tapered surfaces 7, 7 of the fixing rings 5, 5 are slid and guided diagonally outward in the radial direction along the tapered surfaces 6A, 6B of the inner races 3A, 3B. Therefore, the tension force acting on the inner races 3A, 3B from the fixing rings 5, 5 is absorbed, so that no excessive force is applied to the inner races 3A, 3B and the inner races 3A, 3B are not damaged. Only

As in this embodiment, if the fitting gap between the swing shaft 2 and the inner races 3A and 3B is set to be sufficiently large in advance, the outer peripheral surface of the swing shaft 2 and the inner race 3
It is not necessary to control the dimensional accuracy of the inner peripheral surface of each of the A and 3B with high accuracy, so that not only the manufacturing is facilitated but also the manufacturing cost can be reduced. Further, when the swing shaft 2 swings, the fixing rings 5, 5 and the inner races 3A, 3B
And the edge does not come into contact with the edge, so that chipping of the end faces of the ceramic inner races 3A and 3B can be prevented.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, unlike the above embodiment, the bearing housing 1 is made of metal such as SUS304, and the swing shaft 2 is made of a material that approximates the linear expansion coefficient of the inner races 3A and 3B, thereby solving the problem on the outer race 4 side. An example is given.

In this embodiment, fixing rings 8 are used for positioning and fixing the outer race 4 to the bearing housing 1. Although the fixing rings 8 and 8 have substantially the same external shape as the fixing rings 5 and 5 shown in FIG. Fig. 1
And fixing rings 5, 5. In addition, outside race 4
Are tapered surfaces 10A and 10B that increase in diameter from the center in the axial direction to both end surfaces on both sides in the axial direction of the inner peripheral surface.
Are formed, and the tapered surfaces 9, 9 of the two fixing rings 8, 8 are pressed against the tapered surfaces 10A, 10B, respectively.

The operation will be described. When the temperature rises, the bearing housing 1 and the fixing rings 8, 8 are thermally expanded to increase their hole diameters, while the outer race 4 made of ceramics hardly expands. The race 4 will be pulled radially outward, so that the outer race 4 will remain in a concentric position with the bearing housing 1. Even if the fixing rings 8, 8 are thermally expanded in this way, the tapered surfaces 9, 9 thereof are slid and guided obliquely outward in the radial direction along the tapered surfaces 10A, 10B of the outer race 4. Since the pulling force acting on the outer race 4 from the rings 8, 8 is absorbed, no excessive force is applied to the outer race 4, so that the outer race 4 does not have to be damaged.

Also in this embodiment, since the fitting gap between the bearing housing 1 and the outer race 4 is set to be sufficiently large in advance, the dimensions of the inner peripheral surface of the bearing housing 1 and the outer peripheral surface of the outer race 4 are set. It is not necessary to control the precision with high precision, which not only facilitates the production but also contributes to the reduction of the production cost. Further, when the bearing housing 1 swings, the fixing rings 8, 8 and the outer race 4 come into contact with each other and do not come into contact with the edge.
Chipping of the outer race 4 made of ceramics can be prevented.

FIG. 4 shows a third embodiment of the present invention. This embodiment exemplifies an example in which the structures shown in FIGS. 1 and 3 are combined, and measures against a rise in temperature are taken for both the inner races 3A and 3B and the outer race 4. In this embodiment, the bearing housing 1 and the swing shaft 2 are, for example, SUS3
04 and other metals. Since the configuration and operation of this embodiment are obtained by combining the above-described two embodiments, detailed description thereof will be omitted.

In each of the above embodiments, the relationship between the outer peripheral surfaces of the inner races 3A and 3B and the inner peripheral surface of the outer race 4 may be reversed. Contrary to the above embodiment, the inner race is formed in an annular shape and the outer race is formed into two semicircular ones, or a groove is formed in the outer race to form both the inner race and the outer race. The present invention is also applicable to a ring-shaped one.

[0031]

[Effects of the Invention] As described above, according to the present invention,
The following effects can be obtained.

In the first ceramic spherical plain bearing of the present invention, even if the oscillating shaft having a larger linear expansion coefficient than the ceramics does not thermally expand, the oscillating shaft does not receive an excessive pressing force from the oscillating shaft. Can be prevented. Moreover, since the inner race can be arranged concentrically with the swing shaft regardless of the presence or absence of thermal expansion of the swing shaft, the support state of the swing shaft can be always stabilized. In addition, because the clearance between the inner race and the swinging shaft is sufficiently large, it is not necessary to control the dimensional accuracy of each fitting surface between the swinging shaft and the inner race with high precision. It can contribute to cost reduction.

In the second ceramic spherical plain bearing of the present invention, the outer race can be arranged concentrically with the oscillating shaft regardless of the presence or absence of thermal expansion of the bearing housing having a larger linear expansion coefficient than the ceramic. This makes it possible to always stabilize the support state of the oscillating shaft supported via the spherical plain bearing.

In each of the first and second ceramic spherical plain bearings of the present invention, since the fixing ring and the inner and outer races are in contact with each other on the tapered surfaces, the inner and outer races are mounted. Even when the fixing ring and the inner and outer races are brought into contact with each other and do not come into contact with the edges even when they are swung by the other party (the swinging shaft and the bearing housing), the ceramic inner and outer races can be prevented from being chipped.

In the third ceramic spherical plain bearing of the present invention, the functions and effects of the first and second ceramic spherical plain bearings of the present invention can be simultaneously exhibited, so that the coefficient of linear expansion is larger than that of ceramics. Since it can be mounted in a preferable state without any problem between the swing shaft and the bearing housing, it can greatly contribute to the practical use of ceramic spherical plain bearings.

[Brief description of the drawings]

FIG. 1 is a first view of a ceramic spherical plain bearing of the present invention.
The longitudinal section of an example.

FIG. 2 is a side view of FIG. 1;

FIG. 3 is a second view of the ceramic spherical plain bearing of the present invention.
The longitudinal section of an example.

FIG. 4 shows a third embodiment of the ceramic spherical plain bearing of the present invention.
The longitudinal section of an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bearing housing 2 Oscillating shaft 3A, 3B Inner race 4 Outer race 5, 5 Inner race fixing ring 6A, 6B Inner race taper surface 7, 7 Taper surface of fixing ring 8, 8 Outer race fixing ring 9, 9 Tapered surface of fixing ring 10,10 Tapered surface of outer race

Claims (3)

(57) [Scope of request for utility model registration] 1. A radially outer peripheral surface of a ceramic inner race is formed in a convex or concave shape having a constant curvature in a radial direction, and a radially inner peripheral surface of a ceramic outer race is also curved with respect to the radial direction. A ceramic spherical plain bearing formed in a concave or convex shape with a curvature that matches or almost matches with the inner race, wherein the inner race has a required gap on the outer periphery of a shaft having a larger linear expansion coefficient than the inner race made of ceramics. Placed
And, the inner race is sandwiched from both sides in the axial direction by two fixing rings attached to the shaft, and each contact surface between the two fixing rings and the inner race is located near the center of the inner race in the axial direction. A ceramic spherical plain bearing characterized in that it is formed concentrically on a shaft by being formed on a tapered surface whose diameter increases toward both sides. 2. A radial inner peripheral surface of a ceramic inner race is formed in a convex or concave shape having a constant curvature in a radial direction, and a radial inner peripheral surface of the ceramic outer race is also curved in the radial direction. A ceramic spherical plain bearing formed in a concave or convex shape with a curvature that matches or almost matches with the outer race, wherein the outer race is disposed on the inner periphery of a bearing housing having a larger linear expansion coefficient than the outer race made of ceramic; and ,
The outer race is sandwiched from both sides in the axial direction by two fixing rings mounted on the bearing housing, and each contact surface between the two fixing rings and the outer race is formed on both sides from the axial center of the outer race. A spherical bearing made of ceramics, characterized in that it is formed concentrically on a shaft on which an inner race is mounted by being formed on a tapered surface whose diameter increases toward the direction. 3. A radially outer peripheral surface of a ceramic inner race is formed in a convex or concave shape having a constant curvature in a radial direction, and a radially inner peripheral surface of a ceramic outer race is similarly curved with respect to the radial direction. A ceramic spherical plain bearing formed in a concave or convex shape with a curvature that matches or almost matches with the inner race, wherein the inner race has a required gap on the outer periphery of a shaft having a larger linear expansion coefficient than the inner race made of ceramics. Placed
And, the inner race is sandwiched from both sides in the axial direction by two fixing rings attached to the shaft, and each contact surface between the two fixing rings and the inner race is located near the center of the inner race in the axial direction. The outer race is arranged on the inner periphery of a bearing housing having a larger linear expansion coefficient than the ceramic outer race by being formed concentrically on the shaft by being formed on a tapered surface whose diameter increases toward both sides. And
Further, the outer race is sandwiched from both sides in the axial direction by two fixing rings mounted on the bearing housing, and each contact surface between the two fixing rings and the outer race is closer to the axial center of the outer race. A spherical plain bearing made of ceramics, which is formed concentrically on the shaft by being formed on a tapered surface that increases in diameter from both sides toward the shaft.