JPH0810014B2 - Ceramic bearing unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a ceramic bearing unit in which a ceramic bearing constituted by a ceramic inner race and a ceramic outer race is housed in a housing.

<Prior Art> Conventionally, a bearing such as a sliding bearing or a rolling bearing has been used when a rotary shaft is attached to a frame.

The rolling bearing is configured by providing rolling elements such as balls, rollers and needles between an outer race fitted to a housing formed in a machine frame or the like and an inner race fitted to a rotary shaft. There are various types of rolling bearings, such as ball bearings, roller bearings, needle bearings, etc., depending on the rolling elements used, and radial bearings, thrust bearings, etc., depending on how the load is received (Japanese Patent Publication No. 49-41231). etc). Among these bearings, bearings such as deep groove ball bearings, angular ball bearings and tapered roller bearings are used as bearings capable of simultaneously supporting thrust load and radial load.

The slide bearing is formed by laminating a white metal layer on a metal support such as steel, cast iron or copper, and finishing the metal layer to a predetermined diameter by machining,
There is a structure in which an oil-impregnated alloy layer is laminated or embedded on a metal support such as copper or gun metal.

The bearing formed by forming the metal support in the shape of a sleeve is used as a radial bearing for bearing a radial load (Japanese Patent Publication No. 18885/1974), and the metal support is formed in the shape of a disk. Bearings are used as bearings for bearing thrust loads (Japanese Patent Publication No. 49-
687 publication).

The rolling bearing and the sliding bearing have their own unique characteristics, and the most suitable bearing is adopted in consideration of the characteristics of each bearing.

Further, the bearing unit configured by housing the rolling bearing or the sliding bearing as described above in the housing is widely used in the machine industry, the equipment industry and the like.

<Problems to be Solved by the Invention> In the above bearing unit, when a rolling bearing is used, flaking due to rolling fatigue occurs in the bearing, so that the life is inevitably determined and the heat resistance is low. There is a problem that the cost is high due to the large number of components, and when a sliding bearing is used, the shaft and the inner peripheral surface of the sliding bearing make sliding contact, so the shaft becomes thin during long-term use. May come.

An object of the present invention is to provide a ceramics bearing unit in which a ceramics bearing formed by combining a ceramics inner race and a ceramics outer race is housed in a housing.

<Means for Solving the Problems> In order to solve the above problems, the ceramic bearing unit of the present invention has a shaft hole for fitting a shaft in the center and a plurality of points on the shaft center on the outer peripheral surface. A ceramic inner race formed with a convex curved surface in which spherical surfaces each having a center and different radii are connected to each other and an abutting surface for abutting an end face of a shaft is formed, and the inner race is formed with the ceramic inner race. A ceramic outer race that rotatably accommodates the ceramic inner race by forming a concave curved surface that matches the convex curved surface and using the concave curved surface as a sliding surface, and a mounting hole that non-rotatably accommodates the ceramic outer race And a housing formed with.

<Operation> According to the above means, the convex curved surface is formed by forming the shaft hole for fitting the shaft at the center and continuously forming the spherical surface having different radii about the plurality of points on the outer peripheral surface as the centers. And a ceramic inner race (hereinafter referred to as "inner race") that forms an abutment surface that comes into contact with the end surface of the shaft, and a concave surface that matches the convex curved surface of the inner race A ceramic outer race that rotatably accommodates the inner race with the concave surface as the sliding surface (hereinafter referred to as "outer race").
The above is used to form a ceramic bearing, and the outer race is non-rotatably housed in the housing, and a mounting hole for mounting the ceramic bearing unit at a predetermined position is formed in the housing. By fixing the ceramic bearing unit to a predetermined position in a machine or the like through the hole and fitting the shaft into the shaft hole formed in the inner race, the shaft on which the thrust load or radial load acts can be set to the predetermined position. Can be supported in.

<Example> An example of a bearing to which the above means is applied will be described below with reference to the drawings.

[First Embodiment] FIG. 1 (A) is a cross-sectional explanatory view of a ceramics bearing unit, FIG. 1 (B) is a frontal explanatory view, and FIG. 2 is an explanatory diagram of a ceramics bearing unit in use.

The ceramic bearing unit of the present embodiment is configured so that when the shaft on which the thrust load acts is supported, the shaft can be supported only on one surface of the bearing unit.

In the figure, a ceramic bearing unit A is composed of an inner race 1, an outer race 2 and a housing 3. The inner race 1 and the outer race 2 are made of alumina or PS
It is formed by filling an oxide-based ceramic raw material such as Z into a molding die, molding by press molding, and firing at about 1500 to 1600 ° C.

On the inner peripheral surface of the inner race 1, the axial center 4 of the inner race 1 is
A shaft hole 5 for fitting the journal portion B ₁ of the shaft B is formed in conformity with.

A convex curved surface 1a is formed on the outer shape of the inner race 1. The end face of the inner race 1 is formed as an abutment surface 1b for abutting the end face B ₂ of the shaft B.

The convex curved surface 1a is a surface serving as a sliding surface that makes sliding contact with a concave surface 2c formed on the inner peripheral surface of the outer race 2 described later. The convex curved surface 1a is formed by arranging a plurality of points on the axis 4 as a center and connecting spherical surfaces formed with respective predetermined radii from the center.

The contact surface 1b contacts the end surface B ₂ formed on the shaft B, and the thrust load acting on the shaft B is transmitted to the contact surface 1b.
On the other hand, it is formed with a highly accurate right-angled surface. The contact surface 1b is set at a position that protrudes from the end face 3b of the housing 3 to be described later, thereby when the said surface 1b end face B ₂ of the shaft B is in contact, the end face B ₂ of the housing 3 It is configured so as not to contact the end face.

The journal portion B ₁ of the shaft B is fitted into the shaft hole 5, and the radial load acting on the shaft B is transmitted. Therefore, the shaft hole 5 is formed with a predetermined tolerance with respect to the diameter of the journal portion B ₁ of the shaft B.

The outer race 2 has a concave surface 2c formed on the inner peripheral surface thereof and adapted to the convex curved surface 1a formed on the inner race 1. Outside race 2
The outer shape of is formed by a cylindrical outer peripheral portion 2a and an end surface 2b. The outer peripheral portion 2a is a mating surface when it is mounted in the housing hole 3c formed in the housing 3. Therefore, the outer peripheral portion 2a is formed parallel to the axis 4 and has a predetermined diameter. It is formed with a certain tolerance.

It is not necessary that the shape of the convex curved surface 1a and the shape of the concave surface 2c are completely the same.For example, when the convex curved surface 1a is composed of a complex curved surface and a conical surface, the shape of the concave surface 2c is convex. It is possible to form a curved surface that matches the curved surface that forms the curved surface 1a, and when the convex curved surface 1a is formed only by a curved surface, the shape of the concave surface 2c is the curved surface formed on the convex curved surface 1a. It is also possible to form a plurality of curved surfaces with an escape groove formed in the approximate center of the curved surface. That is, the convex curved surface 1a and the concave surface 2c do not necessarily have to be in full contact with each other, and by reducing the contact area between them, it is possible to reduce the heat generated by slippage.

The outer race 2 is formed with a through hole 2d for penetrating the axis B which coincides with the axis 4.

The housing 3 is made of metal such as aluminum or cast iron, or plastic. The housing 3 is composed of a boss portion 3a and an elliptical flange 3b formed at the end of the boss portion 3a. A housing hole 3c for housing the outer race 2 in a non-rotatable manner is formed in the boss portion 3a of the housing 3 so as to coincide with the shaft center 4. The housing hole 3c can be formed so as to penetrate the housing 3, but in the present embodiment, it is formed as a blind hole having a bottom portion 3d. A hole 3e for penetrating the axis B is formed in the bottom portion 3d so as to coincide with the axis 4.

A locking ring 6 is detachably attached to the housing hole 3c for preventing the inner race 1 from falling off when the inner race 1 and the outer race 2 are housed in the hole 3c.

When housing the inner race and the outer race 2 of the housing hole 3c of the housing 3 formed as described above, the outer race 2 is inserted from the open side of the housing hole 3c and press-fitted until it reaches the bottom portion 3d of the housing 3. The outer race 2 can be housed in the housing 3 in a non-rotatable manner. Next, the inner race 1 is housed in the outer race 2 and the locking ring 6 is mounted in the housing hole 3c so that the outer race 2 cannot be rotated in the housing hole 3c of the housing 3 and the inner race 1 can be rotated. The ceramic bearing unit A can be housed in.

The flange 3b is formed with a mounting hole 7 for mounting the ceramic bearing unit A, which is formed by housing the inner race 1 and the outer race 2 in the housing 3, at a predetermined position of, for example, a mechanical device.

Next, a case will be described in which the shaft B on which the thrust load and the radial load simultaneously act is supported by the ceramic bearing unit A configured as described above.

As shown in FIG. 2, the inner race 1 is rotatably accommodated in the outer race 2, and the outer race 2 is non-rotatably accommodated in the housing 3. The journal B ₁ of the shaft B is fitted into the shaft hole 5 and the end face B ₂ of the shaft B is in contact with the contact face 1b formed in the inner race 1, and the bolt or the like is attached to a predetermined position of the machine or the like. Is stuck by.

In the above state, the convex curved surface 1a formed on the outer periphery of the inner race 1 and the concave surface 2c formed on the inner peripheral surface of the outer race 2 are in contact with each other to form a sliding surface. At this time, the axis B is
A thrust load Fs and a radial load Fr are applied, and the combined load F acts on these loads.

The thrust load Fs is transmitted to the inner race 1 via the end surface B ₂ of the shaft B, and the radial load Fr is the journal portion of the shaft B.
It is transmitted to inner race 1 via B ₁ . And the combined load F
The convex curved surface 1a formed on the inner race 1 comes into contact with the concave surface 2c formed on the outer race 2 at a position corresponding to the action direction of
It slides in this position.

At this time, at the contact position between the convex curved surface 1a and the concave surface 2c, a component force in the tangential direction with the concave surface 2c is generated by the combined load F.
The component force acts as a centering force for urging the inner race 1 in the direction of the axis 4, and regardless of the clearance between the concave surface 2c formed on the outer race 2 and the convex curved surface 1a formed on the inner race 1, It acts so that the axis B coincides with the axis 4. That is,
When the shaft B rotates, the shaft B is eccentrically rotated between the convex curved surface 1a and the concave surface 2c according to a clearance due to a centrifugal force. At this time, since the centering force acts on the inner race 1, the centering force overcomes the centrifugal force and the inner race 1 is always operated.
, That is, the axis B is aligned with the axis 4.

Further, when the convex curved surface 1a formed on the inner race 1 and the concave surface 2c formed on the outer race 2 come into sliding contact with each other, heat is generated at the contact surface, but the inner race 1 and the outer race 2 are formed of ceramics. Therefore, the influence of heat on the ceramic bearing unit A is small. That is, the ceramic bearing unit A does not deteriorate due to heat. Also, since the coefficient of thermal expansion is about 8-11 × 10 ^-6 / ° C,
Excessive thermal stress due to thermal expansion does not occur.

[Second Embodiment] FIGS. 3A and 3B are explanatory views of a second embodiment of the ceramic bearing unit, and FIG. 3A is a front explanatory view,
FIG. 3B is a cross sectional view. In the figure, the same parts and parts having the same functions as those in the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The ceramic bearing unit of the present embodiment is configured so that when the shaft on which the thrust load acts is supported, the shaft can be supported on either of the two surfaces of the bearing unit.

In the figure, a ring-shaped ridge 8a, which is a convex curved surface, is formed on the outer periphery of the inner race 8 and at a substantially central portion in the longitudinal direction. The ridge 8a can be formed in a spherical shape having the center at the axis 4, but it can also be formed as a compound curved surface of a spherical surface and a conical surface as in the above-described embodiment.
Incidentally, FIG. 3 (B) shows a case where the ridge 8a is formed by a compound curved surface of a spherical surface and a conical curved surface.

Both end faces of the inner race 8, when the axis B is fitted into the shaft hole 5, the end face B ₂ of the shaft B is formed as a contact with contact surface 8b, the figure in the present embodiment (B) Contact surface 8b as shown in
Is configured to project from the end surface of the housing 10. That is, the length of the inner race 8 is formed longer than the width of the housing 10.

The outer race 9 is composed of two halves 11 and 12 which, when combined, have a concave surface 9c which is formed on the inner peripheral surface of the inner race 8 so as to match the convex strip 8a. The halves 11 and 12 are molded by the same manufacturing method as the inner race 1 and the outer race 2 described in the above-mentioned embodiment.

In the present embodiment, the housing 10 is configured so that the axial direction of the fitted shaft and the mounting direction of the housing 10 are at right angles as shown in the drawing.

The housing hole 10c formed in the housing 10 is formed as a through hole. In order to store the storage hole 10c thus formed and the outer race 9, the half body 11 or 12 is placed in the storage hole 10c.
After press-fitting and then inserting the inner race 8, the remaining half
It is possible to press-fit 12 or 11. The inner race 8 is rotatably housed between the halves 11 and 12 in advance, and the halves 11 and 12 are bonded or fused to form a bearing, which is press-fitted into the housing hole 10c. Is also possible.

The combinations of the respective bearings and the housings 3 and 10 by the combination of the inner race 1 and the outer race 2 and the inner race 8 and the outer race 9 described in each of the above-described embodiments are limited to these embodiments. But a bearing and a housing composed of an inner race 1 and an outer race 2, for example.
The bearing unit A can be combined with 10 and the bearing formed by the inner race 8 and the outer race 9 can be combined with the housing 3 to form the bearing unit A.

The bottom portion 3d formed in the housing hole 3c of the housing 3 does not necessarily have to be formed, and may be a through hole like the housing hole 10c formed in the housing 10.

<Effects of the Invention> As described in detail above, according to the ceramic bearing unit of the present invention, the shaft hole for fitting the shaft is formed in the center and a plurality of points on the shaft center are formed on the outer peripheral surface. And an inner race made of ceramics in which a convex curved surface formed by connecting spherical surfaces each having a different radius is formed and an abutting surface for abutting the end face of the shaft is formed, and the inner curved surface is fitted with the convex curved surface of the inner race. A ceramic bearing is formed by combining a concave outer surface and a ceramic outer race that rotatably accommodates the inner race with the concave surface as a sliding surface, and the outer race is non-rotatably accommodated in the housing. In addition, since the mounting hole for mounting the ceramics bearing unit at a predetermined position is formed in the housing, the ceramics bearing unit can be mounted on a machine through the mounting hole. By fixing the shaft in a predetermined position and fitting the shaft into the shaft hole formed in the inner race, the shaft on which the thrust load or the radial load acts can be supported at the predetermined position.

Therefore, it is not necessary to form a highly accurate hole for accommodating the outer race in the mechanical device or the like, and it is possible to configure a ceramic bearing unit that is easy to use and has high versatility.

Further, by making the concave surface formed on the inner peripheral surface of the outer race a curved surface that matches the convex curved surface formed on the inner race, the contact surface between the convex curved surface and the concave surface can be configured as a sliding surface. For this reason, slippage does not occur between the shaft and the bearing, and therefore the shaft does not become thin.

Further, since the ceramic bearing unit can be composed of the inner race, the outer race and the housing, the number of parts can be reduced as compared with the conventional rolling bearing, and therefore the cost can be reduced.

Further, it has a feature that it is possible to rationally support even a shaft on which a thrust load and a radial load simultaneously act, which is difficult to support by a conventional plain bearing.

[Brief description of drawings]

FIG. 1 (A) is a cross-sectional explanatory view of the ceramics bearing unit, FIG. 1 (B) is a frontal explanatory view, FIG. 2 is an explanatory view of the ceramics bearing unit in use, and FIGS. 2B is an explanatory view of the second embodiment of the ceramic bearing unit, FIG. 3A is a front explanatory view, and FIG. 2B is a sectional explanatory view. A is a ceramic bearing unit, B is a shaft, B ₁ is a journal part, B ₂ is an end face, 1 and 8 are inner races, 1 a is a convex curved surface, 1 b and 8 b
Is a contact surface, 2 and 9 are outer races, 2a is an outer peripheral portion, 2b is an end surface, 2c,
9c is a concave surface, 3 and 10 are housings, 3c and 10c are receiving holes 4, 5 is a shaft hole, 5 is a shaft hole, 6 is a locking ring, 7 is a mounting hole, 8a is a ridge, and 11 and 12 are half bodies. .

Claims (1)

[Claims] 1. A convex curved surface is formed in which a shaft hole for fitting a shaft is formed in the center and a continuous spherical surface centered at a plurality of points on the axis and having different radii is formed on the outer peripheral surface. And an inner race made of ceramics, which forms an abutting surface that comes into contact with the end face of the shaft, and a concave curved surface that matches the convex curved surface formed on the inner race made of ceramics is formed on the inner peripheral surface and the concave curved surface is used as a sliding surface. A ceramic bearing unit comprising: a ceramic outer race that rotatably accommodates the ceramic inner race; and a housing that non-rotatably accommodates the ceramic outer race and has a mounting hole formed therein.