JPH0510331A - Sintered oil-impregnated bearing - Google Patents

Abstract

PURPOSE:To provide sintered, oil-impregnated bearings having no directivity for matted faces in the peripheral direction and requiring no positioning in the peripheral direction for assembling. CONSTITUTION:Sintered, oil-impregnated bearings 1, 2 held by a bearing holder 3 and rotatably supporting a rotary shaft 4 have non-porous faces 1a, 2a on the inner periphery faces, the matted faces 1a, 2a are provided on the open end side in the axial direction of the bearing holder 3, and porous faces 1b, 2b are provided on the remaining inner periphery faces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered oil-impregnated bearing suitable for, for example, a capstan motor.

[0002]

2. Description of the Related Art A capstan motor or the like includes a pair of sintered oil-impregnated bearings 11 in a bearing holder 13 as shown in FIG.
There is one in which 12 is press-fitted and the capstan shaft 14 is rotatably supported by the sintered oil-impregnated bearings 11 and 12. Since a pinch roller (not shown) is pressed against the capstan shaft 14, a lateral pressure is applied from a certain direction as indicated by an arrow, and the capstan shaft 14 is urged from a certain direction in accordance with this lateral pressure so that the inner peripheral surfaces of the sintered oil-impregnated bearings 11 and 12 are pressed. Can be pressed against.

As described above, the device is devised so that lubrication in the sintered oil-impregnated bearings 11 and 12 can be smoothly performed even when a lateral pressure load is applied to the inner peripheral surface. FIG. 8 shows a mechanism of lubrication in such a sintered oil-impregnated bearing, and the dimensional relationship between the bearing 11 and the capstan shaft 14 is extremely differently drawn.
If the capstan shaft 14 that is rotationally driven in the clockwise direction in FIG. 8 is pressed against the inner peripheral wall surface of the bearing 11 by applying a lateral pressure in the direction indicated by the arrow 15, the porous surface of the bearing 11 will be described. The lubricating oil exuding from the surface (hereinafter referred to as “porous”) is scraped off by the outer peripheral surface of the capstan shaft 14 to form an oil wedge 16 between the lubricating oil and the inner peripheral surface of the bearing 11. If the size of the minute holes on the porous surface that supports the lateral pressure load of the bearing 11 is a normal size, the oil escapes to this porous surface, and the capstan is formed on the inner peripheral surface of the bearing 11. So-called boundary lubrication, in which the shaft 14 comes into direct contact, results in increased frictional resistance.

However, when the capstan shaft 14 is rotationally driven and aged for a while while the capstan shaft 14 is in direct contact with the inner peripheral surface of the bearing 11, the above-mentioned capstan of the inner peripheral surface of the bearing 11 is carried out. The portion that bears the lateral pressure load due to the sliding contact of the shaft 14 is plastically deformed by friction, and the porous surface of this portion is crushed and miniaturized. Therefore, the lubricating oil does not escape from the sliding contact portion with the capstan shaft 14, and hydraulic pressure is generated in the sliding contact portion to form so-called fluid lubrication in which the lubricating oil intervenes, so that the frictional resistance decreases. In FIG. 8, reference numeral 17 indicates the hydraulic pressure distribution in the sliding contact portion. After the aging is completed in this way, the frictional resistance decreases and the motor current value also decreases.

FIG. 7 shows a sintered oil-impregnated bearing 11 in which a crushed surface 11a is provided on a part of the inner peripheral surface as described above. The crushed surface 11a is formed over the entire axial length of the bearing 11 and over an angular range of approximately 60 ° in the circumferential direction.

Although the above example is an example of performing aging, there is also a sintered oil-impregnated bearing called an ageless metal in which a blunt surface is formed on a part of the inner peripheral surface from the beginning. FIG. 9 shows an example of a method for obtaining such an ageless sintered oil-impregnated bearing. A portion 11c having an inner diameter smaller than that of a finished product is formed in advance on the inner peripheral side of the bearing 11 over an angle θ range. Part 1 with small inner diameter when sizing
By cutting 1c to form a predetermined inner diameter surface 11d, the predetermined inner diameter surface 11d is used as a crushed surface over the range of the angle θ. The angle θ is about 60 °.

In any case, since the crushed surface of the inner peripheral surface of the conventional sintered oil-impregnated bearing is formed over the entire axial length of the bearing, if the angular range in the peripheral direction is made too large, the porous surface will be changed. The amount of lubricating oil that oozes out and is supplied to the sliding contact portion with the capstan shaft decreases, resulting in poor lubrication. Therefore, the angular range of the blind surface in the circumferential direction cannot be made too wide.

[0008]

As described above,
According to the conventional sintered oil-impregnated bearing, the finely crushed surface of the porous surface has a circumferential angular range of only about 60 °, so high positioning accuracy is required when positioning the crushed surface in the lateral pressure load direction. And the assembly workability is not good.
Further, it is considered to add a mark indicating the direction of the blunted surface to each bearing, but if the lateral pressure direction differs depending on the model, it is difficult to automate the assembly. In addition, bearings of different models may be mixed if the angle difference between the directions of the blunting surfaces of the models is small.

The present invention has been made in order to solve such a problem, and provides a sintered oil-impregnated bearing which does not have the directionality of the crushed surface in the circumferential direction and does not require circumferential alignment when assembled. The purpose is to provide.

[0010]

DISCLOSURE OF THE INVENTION The present invention is a sintered oil-impregnated bearing which is held by a bearing holder and rotatably supports a rotating shaft. The sintered oil-impregnated bearing has an inner peripheral surface having a crushed surface, and the crushed surface is a bearing. It is characterized in that it is provided on the axially open end side of the holder, and the remaining inner peripheral surface is a porous surface.

[0011]

[Function] The blind face is provided only on one end side in the axial direction,
On the surface on the other end side in the axial direction, since the microscopic holes have a porous surface of a normal size, the lubricating oil is sufficiently supplied from the inner peripheral surface of the bearing. The blunted surface may be formed on one end side in the axial direction over the entire circumference, and the bearing mounting directionality does not matter. The bearing receives the lateral pressure from the rotating shaft at the crushed surface. Since the lubrication is performed on this crushed surface, the frictional resistance is reduced.

[0012]

Embodiments of the sintered oil-impregnated bearing according to the present invention will be described below with reference to FIGS. 1 to 5. Figure 1
A pair of upper and lower sintered oil-impregnated bearings 1 and 2 are fixed to the inner peripheral side of the bearing holder 3 by means such as press fitting.
The rotary shaft 4 is rotatably supported by the pair of sintered oil-impregnated bearings 1 and 2. The rotary shaft 4 is, for example, a capstan shaft, and lateral pressure is applied in a fixed direction as indicated by an arrow. Due to the lateral pressure applied to the rotary shaft 4, the rotary shaft 4 has ends of the pair of bearings 1 and 2 which are outside each other, that is, the axially open end of the bearing holder 3 (in FIG. It will be supported by the inner peripheral surface of the lower end).

Therefore, the porous surface of the entire inner peripheral surface on the upper end side of the bearing 1 is made into a finely crushed surface 1a, and the remaining inner peripheral surface, that is, the entire inner peripheral surface on the lower end side is made into fine holes of a normal size. As the porous surface 1b, the crushed surface 1a supports the lateral pressure load of the rotating shaft 4. On the other hand, the porous surface of the entire inner peripheral surface of the lower end side of the bearing 2 is a finely crushed surface 2a, and the remaining inner peripheral surface, that is, the entire inner peripheral surface of the upper end side is a micropore of a normal size. As the surface 2b, the crushed surface 2a supports the lateral pressure load of the rotary shaft 4.

FIG. 2 shows in detail one of the above-mentioned bearings 1 and 2, where the axial dimension of the entire bearing 1 is L and the axial dimension of the crushed surface 1a is L _1. , L ₁
Is set to about 1/3 to 1/2 of L.

According to the embodiment described above, the lateral pressure load applied to the rotary shaft 4 is supported by the crushed surfaces 1a and 2a formed at one end sides of the bearings 1 and 2, so that the lubrication at this support portion is performed. Stable oil pressure is generated due to less oil escape. On the other hand, the supply of the lubricating oil to the sliding contact portion with the rotary shaft 4 to which the lateral pressure load is applied is performed from the remaining porous surfaces 1b and 2b excluding the crushed surfaces 1a and 2a, and the porous surfaces 1b and 2b. Since 2b is formed over the entire circumference, the lubricating oil is sufficiently supplied. As a result, the rotary shaft 4 and the bearings 1, 2
The frictional resistance with and the current value of the motor also decrease. Further, the above effects can be obtained without aging the bearing.

In FIG. 1, the inner diameters of the bearings 1 and 2 and the outer diameter of the rotating shaft 4 are made extremely different, but as is clear from FIG. 1, the upper bearing 1 is located closer to the upper end side. The surface pressure received from the rotating shaft 4 becomes higher, and the surface pressure received from the rotating shaft 4 becomes higher as the lower bearing 2 is closer to the lower end side. Therefore, if the porous surface is made finer as the surface pressure becomes higher, a higher effect can be obtained.

Next, an example of a method for manufacturing a sintered oil-impregnated bearing having a crushed surface on one end side in the axial direction will be described. Although the steps of the whole manufacturing method are the same as the conventional ones, the desired sintered oil-impregnated bearing can be obtained only by devising the shape of the core during molding. FIG. 3 shows an example of a molded core, in which a small diameter portion 6a is formed at the tip of the core 6. The difference between the diameter of the main body portion of the core 6 and the diameter of the small diameter portion 6a may be extremely small, but FIG.
Then, the steps are drawn in an extreme shape.

An example of a sintered oil-impregnated bearing molded using the core 6 is shown in FIGS. 4 (a) and 4 (b). 4A and 4B, the sintered oil-impregnated bearing 1 molded using the core 6 has a small diameter portion 1c having an inner diameter A at one end and a large diameter portion 1d having an inner diameter B at the other end. .. The small diameter portion 1c is formed by the small diameter portion 6a of the core 6, and the large diameter portion 1d is formed by the main body portion of the core 6. This is subjected to a normal sizing process. That is, sizing is performed by passing a sizing disc having a constant outer diameter in the axial direction through the inner circumference of the bearing 1. Since the sizing margin of the small-diameter portion 1c is large, the porous surface of this portion is made finer, as shown in FIG.
As shown in FIG. 5, the blind surface 1a is formed. On the other hand, since the large-diameter portion 1d has a small sizing allowance, the porous surface 1b has a rough surface.

The sintered oil-impregnated bearing obtained as described above is formed so that the crushed surface and the porous surface are distributed in the axial direction, and the crushed surface and the porous surface are formed over the entire circumference. Therefore, the bearing may be attached to the bearing holder so that the blunted surface is located at the end portion of the rotating shaft on which the lateral pressure is more largely received, and the circumferential position of the bearing does not matter. Therefore, there is an effect that the circumferential alignment when incorporating the sintered oil-impregnated bearing becomes unnecessary. Further, even if the mounting position of the motor using the sintered oil-impregnated bearing is deviated, the lateral pressure of the rotary shaft is surely supported by the crushed surface, so that the defect due to the displacement of the mounting position does not occur.

The blunted surface is required to be formed at one end of the sintered oil-impregnated bearing and does not necessarily have to be formed over the entire circumference. FIG. 5 shows an example for obtaining such a sintered oil-impregnated bearing. In FIG. 5, the sintered oil-impregnated bearing 8 has a small-diameter portion 8c formed at one end in the axial direction over about half a circumference, and the other has a large-diameter portion 8d. When this is subjected to a normal sizing process, the small-diameter portion 8c of about a half circumference becomes a blunt surface. The bearing 8 may be arranged so that the crushed surface supports the lateral pressure of the rotating shaft.

[0021]

According to the sintered oil-impregnated bearing according to the present invention,
The mesh surface and the porous surface are distributed in the axial direction, and these mesh surface and the porous surface are widely formed in the circumferential direction. It suffices to mount the bearing on the bearing holder so that the surfaces are located, and the circumferential position of the bearing does not matter much. Therefore, there is an effect that the circumferential alignment when the sintered oil-impregnated bearing is assembled becomes easy.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a sintered oil-impregnated bearing according to the present invention.

FIG. 2 is a perspective view showing one bearing in the embodiment, which is cut away.

FIG. 3 is a front view showing an example of a molding core for manufacturing the sintered oil-impregnated bearing of the present invention.

FIG. 4 is a plan view and a cross-sectional view showing an example of a manufacturing process of a sintered oil-impregnated bearing according to the present invention.

FIG. 5 is a plan view showing another embodiment of the sintered oil-impregnated bearing according to the present invention and showing a form in the middle of a manufacturing process.

FIG. 6 is a cross-sectional view showing an example of a capstan using a sintered oil-impregnated bearing.

FIG. 7 is a perspective view showing an example of a conventional sintered oil-impregnated bearing by cutting it.

FIG. 8 is a plan view showing a mechanism for lubrication by a sintered oil-impregnated bearing.

FIG. 9 is a plan view showing an example of a conventional ageless sintered oil-impregnated bearing, showing a form in the middle of a manufacturing process.

[Explanation of symbols]

 1, 2 Sintered oil-impregnated bearings 1a, 2a Crushed surface 1b, 2b Porous surface 4 Rotating shaft

Claims (1)

Claim: What is claimed is: 1. A sintered oil-impregnated bearing, which is held by a bearing holder and rotatably supports a rotating shaft, having a crushed surface on an inner peripheral surface, and the crushed surface is a bearing. A sintered oil-impregnated bearing characterized in that it is provided on the axially open end side of the holder, and the remaining inner peripheral surface is a porous surface.