JP3610396B2 - Hydrodynamic bearing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrodynamic bearing that has a shaft contact portion having a spherical contact structure and a hydrodynamic groove formed on the surface thereof for rotation.
[0002]
[Prior art]
In a hydrodynamic bearing having a spherical contact structure in which a convex spherical surface is provided at the shaft end and the convex spherical surface is received by a concave spherical surface, a dynamic pressure groove is formed on one surface of the convex spherical surface or the concave spherical surface and rotated. As shown in FIG. 5, the dynamic pressure bearing support structure having such a spherical contact structure has a dynamic pressure groove 3 formed on the surface of the ball portion 10 at the end of the shaft 1, and the ball portion is formed in the receiving member 2. A concave spherical surface 21 into which 10 is fitted is formed and supported by contacting at points A and A (actually a circular line including these two points), or as shown in FIG. In the concave spherical surface 21 of the receiving member 2 in which the dynamic pressure groove 3 is formed on the surface of the sphere 10 at the end of the sphere 10 and the sphere 10 is fitted, the radius of curvature is slightly larger than the radius of the sphere 10. In many cases, the structure is formed and supported at the point B. Further, the surface of the spherical portion 10 and the surface of the concave spherical surface 21 are usually finished into a mirror surface by lapping except for the dynamic pressure grooves 3, and have a certain roughness as shown in FIG. It is stored in the range of R _max ≦ 0.4.
[0003]
[Problems to be solved by the invention]
As described above, the hydrodynamic bearing having the spherical contact structure has a shaft 1 when the contact support at points A and A as shown in FIG. 5 or the contact support only at point B as shown in FIG. Since the load is applied in the vertical or horizontal direction to itself, the pressure of the contact part at the time of starting and stopping becomes high, and these parts are easily worn. Therefore, in such a spherical contact portion, there is a problem that if the lubrication state by the lubricant is poor, seizure easily occurs and the life of the bearing is reduced. Further, the surface of the spherical portion 10 or the concave spherical surface 21 is processed into a mirror surface, but there is a problem that such a mirror-like bearing surface is easily wrinkled by wear powder or the like.
[0004]
The present invention has been made by paying attention to the above-mentioned problems, and is a hydrodynamic bearing having a spherical contact structure that is less likely to be worn during starting or stopping, has a high ability to retain a lubricant, and can maintain a long bearing life. The purpose is to provide.
[0005]
[Means for Solving the Problems]
That is, in order to solve the above-mentioned problems, the present invention forms a part of the shaft (1) into a convex spherical surface, and forms a concave spherical surface into which the convex spherical surface is fitted into the receiving member. In a hydrodynamic bearing having a spherical contact structure formed with a dynamic pressure groove on either one, a mirror surface finish is applied to the convex spherical surface formed on the shaft end and the concave spherical surface formed on the receiving member into which the convex spherical surface is fitted, Furthermore, it is characterized in that a satin finish is formed on one of the surfaces with hard fine powder such as alumina powder or diamond powder.
(2) The mirror-finished surface is formed to have a roughness of R _max ≦ 0.4.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
FIG. 1A is a longitudinal sectional view of a conventional dynamic pressure bearing, and FIG. 1B is a longitudinal sectional view of a fluid dynamic bearing portion of the present invention. In addition, in order to avoid duplication description, it demonstrates using the same code | symbol as the code | symbol demonstrated by the prior art for the same element part.
A convex spherical surface 11 is formed at the end of the shaft 1, and the shaft 1 is configured to fit and support the convex spherical surface 11 to a concave spherical surface 21 formed on the receiving member 2. Usually, the convex spherical surface 11 and the concave spherical surface 21 are processed into a mirror surface. Further, a dynamic pressure groove 3 is formed on the convex spherical surface 11, and the shaft 1 is spherically supported on the receiving member 2 by dynamic pressure due to a pumping action when the shaft 1 or the receiving member 2 rotates. The dynamic pressure groove 3 may be formed on the concave spherical surface 21 side.
[0007]
FIG. 2 is a schematic diagram of the surface showing the surface roughness in a state in which the convex spherical surface 11 at the end of the shaft 1 is mirror-finished. The roughness is lapped so that the surface unevenness is in a certain range. Thus, mirror polishing is applied.
[0008]
Next, as shown in FIG. 1B, the surface of the convex surface of the convex spherical surface 11 other than the dynamic pressure groove 3 formed on the shaft 1 is processed in a matte state. That is, the convex spherical surface 11 is finely polished with hard fine powder such as alumina powder, glass fine powder, or powder diamond on the remaining mirror surface portion after mirror finishing and forming the dynamic pressure groove 3 (or before machining). Barrel processing is performed so that the pear texture 11a is formed. That is, the convex spherical surface 11 of the shaft 1 maintains the accuracy as a mirror surface, and a fine uneven surface 11a is formed on the mirror surface. Therefore, the satin in this case is the opposite of the generally specular state (the state where there are few irregularities per area and less irregular reflection) "the state where there are many irregularities per area, and therefore the irregular reflection appears cloudy I mean. However, the roughness is comparable to the mirror finish as described above.
[0009]
FIG. 3 is a schematic diagram of the surface showing the surface roughness in a state in which the convex spherical surface 11 at the end of the shaft 1 is mirror-finished and the mirror surface is processed so as to have a satin finish 11a. When the convex spherical surface 11 at the end of the shaft 1 is mirror-finished and further barreled with hard fine powder, the roughness of the surface is maintained within a certain range and the roughness range is within that range. Fine irregularities are formed on the surface. Since the lubricant G is well held on the unevenness, the lubricating performance is improved and wear is reduced.
[0010]
FIG. 4 shows a perspective view when the concave spherical surface 21 of the receiving member 2 is subjected to a satin finish. That is, in the above embodiment, the convex spherical surface 11 formed at the end of the shaft 1 is mirror finished to form the dynamic pressure groove 3 and the satin 11a. However, the convex spherical surface 11 formed on the shaft 1 is dynamic pressure applied to the mirror finishing. The groove 3 is formed, and the concave spherical surface 21 formed on the receiving member 2 is mirror-finished by lapping, and the mirror-like concave spherical surface 21 is barrel processed with hard fine powder to form a satin finish 21a. Even in this case, the concave spherical surface 21 is formed with a satin finish 21a while maintaining a mirror-like roughness.
[0011]
As described in detail above, according to the present invention, in the hydrodynamic bearing having a spherical contact structure, the convex spherical surface 11 provided with the hydrodynamic groove 3 at the end of the shaft 1 is mirror-finished, and further, alumina powder or fine particles are provided. A satin finish 11a is formed by barrel processing with hard fine powder such as diamond powder, or a mirror finish is applied to the concave spherical surface 21 to which the convex spherical surface 11 of the receiving member 2 receiving the shaft 1 is fitted to form a satin finish 21a. To do. Conventionally, as disclosed in, for example, Japanese Examined Patent Publication No. 60-18850, a steel strip taken out of a cold-rolled steel plate having a glossy surface has a textured surface by chemicals, shot pinning, shot blasting, or the like, or Roughing is performed on one surface of a rotating body as disclosed in Japanese Patent Laid-Open No. 3-86458 or a support that thrust supports the rotating body to a surface roughness of 3 to 5S, and then lapping is performed. However, the invention with a surface roughness of 2 to 3S is known, but the hydrodynamic bearing having a spherical contact structure according to the present invention is different from these preceding examples.
[0012]
【The invention's effect】
As described above in detail, according to the hydrodynamic bearing of the present invention, the holding capacity of the lubricant in the matte surface on the convex spherical surface or concave spherical surface constituting the hydrodynamic bearing is improved, and the pressure at the time of starting or stopping is increased. Even if there is, there is less micro-abrasion. Further, the generated minute wear powder is extremely reduced and the influence on the bearing surface is reduced. In addition, the life of the bearing is increased, and the necessity for stopping or maintaining the parts is reduced.
[Brief description of the drawings]
1A is a longitudinal sectional view of a conventional hydrodynamic bearing, and FIG. 1B is a longitudinal sectional view of a hydrodynamic bearing portion of the present invention.
FIG. 2 is a schematic view of the surface showing the surface roughness in a state where the convex spherical surface at the end of the shaft constituting the conventional hydrodynamic bearing is mirror-finished.
FIG. 3 is a schematic view of the surface showing the surface roughness in a matte state in which the convex spherical surface at the end of the shaft constituting the hydrodynamic bearing of the present invention is mirror-finished and further barrel processed.
FIG. 4 shows a modified embodiment of the hydrodynamic bearing according to the present invention, and is a perspective view in the case where the concave surface of the receiving member is mirror-finished and subjected to a satin finish.
FIG. 5 is a vertical cross-sectional view when a concave spherical surface of a conventional hydrodynamic bearing supports a convex spherical surface on a predetermined line.
FIG. 6 (A) is a longitudinal sectional view when a convex spherical surface of a conventional dynamic pressure bearing is supported at one point of a concave spherical surface, and FIG. 6 (B) is a surface surface showing the surface roughness in that case. It is a schematic diagram.
[Explanation of symbols]
1 axis 11 convex spherical surface 11a satin 2 receiving member 21 concave spherical surface 21a satin 3 dynamic pressure groove

Claims (2)

A spherical contact structure is formed by forming a part of the shaft into a convex spherical surface, forming a concave spherical surface into which the convex spherical surface is fitted into the receiving member, and forming a dynamic pressure groove on either the convex spherical surface or the concave spherical surface. In the pressure bearing, the convex spherical surface formed on the shaft end portion and the concave spherical surface formed on the receiving member into which the convex spherical surface is fitted are mirror-finished, and further, a satin finish is formed on one of the surfaces with hard fine powder. A hydrodynamic bearing characterized by that. The hydrodynamic bearing according to claim 1, wherein the mirror-finished surface is formed to have a roughness of R _max ≦ 0.4.

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