JPH0830490B2 - Hydrodynamic bearing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydrodynamic bearing.

[Conventional technology]

In recent years, bearings for multi-mirror surface (polygon mirror) rotary shafts, VTR cylinder head spindles, magnetic disk spindles, etc. used in laser beam printers, etc. have been strongly requested to satisfy high-speed and high-precision rotation. 2. Description of the Related Art A hydrodynamic bearing using a gas such as air or a liquid such as lubricating oil as a medium, which has excellent bearing performance such as very small unevenness and small torque, has been used. In such a hydrodynamic bearing, a high-pressure fluid layer is generated between the stationary side and the rotating side during steady rotation, and a minute gap (about 2 to 10 μm) is created.
It is characterized by rotating without contact while holding
The bearing performance (rotational accuracy, rotational unevenness, rotational torque, etc.) also derives from it. The guarantee of such a minute gap is extremely important for preventing fatal troubles for bearings such as deterioration of bearing performance and seizure due to deterioration of grease, oil, etc. due to wear powder on the fixed side and rotating side. is important. In this type of hydrodynamic bearing (including radial and thrust), the facing surfaces have been in contact with each other at the time of start and stop, and in order to minimize the surface wear that accompanies this contact, the facing surfaces are hardened or hardened. It was necessary to harden the surface such as plating. Further, when the bearing is hardened, distortion occurs in the bearing, and in the case of hard plating, it is not easy to control the thickness of the plating layer with high accuracy to perform plating. Therefore, it was necessary to finish the surface again by a method such as polishing. Even with such curing means, abrasion powder from the surface accelerates deterioration of liquids such as grease and other lubricating oils, often causing changes in rotational torque. I couldn't say. Further, since the surface energy of these metal-based surfaces is large, there is an inherent drawback that the resistance to movement of the liquid is large and the time required for steady rotation after the start of operation is long.

[Problems to be solved by the invention]

As described above, the conventional technique has a problem that it is not possible to obtain a hydrodynamic bearing that suppresses the generation of wear powder by simple processing as much as possible and that has a short time to reach steady rotation after the start of operation. was there.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention is directed to at least one of the facing surfaces of a hydrodynamic bearing having a groove for guiding a fluid in a fixed direction on at least one of the facing surfaces. In at least one of the above, a means for providing a hydrodynamic bearing in which a polyfluoroalkyl polymer having a functional group or a fluoropolyether polymer having a functional group is coated is adopted. The details are described below.

In addition, the organopolysiloxane having a functional group in the reference example described later is, for example, one obtained by introducing a functional group into a homopolymer or a copolymer of two or more kinds of siloxanes such as dimethylsiloxane, methylphenylsiloxane, and trimethylfluoropropylsiloxane. The functional group is, for example, an epoxy group, an amino group, a carboxyl group, a hydroxyl group, a mercapto group, an isocyanate group, a cyanate group, a vinyl group, an alkoxyl group or an alkoxycarbonyl group. The vinyl group-containing polysiloxane is preferably used together with the silicon atom-bonded hydrogen-containing polysiloxane.

Specific examples of introducing these functional groups are as follows, but the examples for each functional group are not limited to those described.

As those containing epoxy groups As those containing amino groups As those containing carboxyl groups As those containing alcoholic hydroxyl groups As those containing a mercapto group Isocyanate group-containing As those containing vinyl groups As a silicon atom-bonded hydrogen-containing substance that is desired to be used in combination with this vinyl group-containing substance. And so on. Here, R in the formula is an alkylene group or the like, m is 5 to 1000, and n is 2 to 100.

Among the polyfluoroalkyl polymer or fluoropolyether polymer in the present invention, the polyfluoroalkyl polymer is a fluoroalkyl group such as F ₃ CCF _{2 7} , HCF _{2 6} , ClF ₂ CCF _{2 11} , The fluoropolyether polymer has a main structural unit represented by the general formula —C _X F _2X —O— [where X is an integer of 1 to 4] and has an average molecular weight of about 1000 to
It is a polymer of 50,000. And these fluorine-containing polymers also have functional groups such as epoxy groups, amino groups, carboxyl groups, hydroxyl groups, mercapto groups, isocyanate groups, and cyanate groups introduced in the same manner as the above-mentioned organopolysiloxanes. The thing can be illustrated. That is, OCNCH _{2 6} NHCO-C ₆ F ₁₂ -CONHCH ₂ NCO, C ₈ F ₁₇ C ₂ H ₄ OH, C ₁₀ F ₂₁ CONHC ₂ H ₄ OH, _{C 6 F 13 SCH 2 CH 2} OCOCH 2 5 NH 2, C 8 F 17 SO 2 F, _{HOOC-CF 2 OC 2 F 4} O m CF 2 O n CF 2 COOH, _{H 3 COOC-CF 2 OC 2} F 4 O m CF 2 O n CF 2 COOCH 3, HOCH 2 -CF 2 C 2 F 4 O m CF 2 O n CF 2 -CH 2 OH, And so on.

When two or more kinds of polymers having the above-mentioned functional groups are used in combination, the functional groups which each polymer has as a unit are combined so as to react with each other, and the molecular weight of the polymer is further increased by the reaction. It is preferable because it can be coated with a strong film having increased lubricity. For example, a combination of a polymer whose functional group is an epoxy group and an amino group, a carboxyl group, a hydroxyl group, a polymer containing at least one kind of group selected from the functional groups of mercapto groups,
A functional group is a carboxyl group or an ester group, a polymer and an amino group, a combination of a polymer containing at least one group selected from a hydroxyl group, a functional group is a polymer and a hydroxyl group containing an isocyanate group or a cyanate group, Amino group, mercapto group, combination with a polymer containing at least one type of group selected from a carboxyl group,
A preferred example is a combination of a polymer having a vinyl group as a functional group and a polymer having a silicon atom-bonded hydrogen, or a combination such as a hydroxyl group, an alkoxyl group, or an alkoxycarbonyl group which is polymerized by a condensation reaction. In such a combination, a catalyst that promotes the reaction between the respective functional groups may be added.

[Action]

In the present invention, the polyfluoroalkyl polymer or the fluoropolyether polymer is a polymer which itself exhibits excellent lubricity, and since its molecule has a highly reactive functional group, it reacts with the metal surface to bond. A lubricious film will be formed. Due to this coating, in the dynamic pressure bearing, wear due to contact of the facing surfaces after start and stop does not occur, and the surface energy decreases, so the movement resistance of the liquid is small, so it is possible to reach steady rotation after the start of operation. The time is short and there is no rust.

〔Example〕

Example 1: Isocyanate group-containing polyfluoroether (manufactured by Monte Fluos in Italy: Fomblin Z DISOC-2000, molecular weight 200)
0) is uniformly dispersed in a highly fluorinated organic solvent such as Freon R113, and is applied to the inner surface of the housing 1 of the hydrodynamic bearing as shown in the figure, and baked at 150 ° C for 2 hours to form a coating film. Formed. Specific coating methods include dipping, spraying,
The method is not particularly limited as long as it is a widely used method such as a brush coating method, but the immersion method is the most economical and preferable in view of waste of the liquid. After coating, the film is obtained by evaporating the solvent, but the film thickness is 0.01-2.0μ.
A range of m is desirable. Because, it is difficult to obtain the expected wear resistance and lubricity with a thin film of less than 0.01 μm, and 2.
This is because, in the case of a thick film having a thickness of more than 0 μm, the terminal reactive groups do not react sufficiently and remain unreacted, so that the original lubricity of the resin is deteriorated and dimensional control becomes difficult, which is not preferable.

Reference Example 1: Epoxy group-containing organopolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd .: epoxy-modified silicone oil KF102) and amino group-containing organopolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd .:
Shaft 2 of the hydrodynamic bearing, which shows a liquid prepared by dispersing a 1: 1 mixture of amino-modified silicone oil KF861) in Freon R113.
Was applied to the surface of and was baked at 150 ° C. for 2 hours to form a coating film. The same good results as in Example 1 were obtained.

〔effect〕

From the above, the hydrodynamic bearing of the present invention does not need to be subjected to an effect treatment of the bearing surface, and a surface with abrasion resistance can be formed while maintaining dimensional accuracy by simple processing, so that The generation of wear debris due to surface contact at the time of starting is suppressed as much as possible, and it is extremely effective in preventing fatal problems such as grease and oil deterioration due to wear debris for bearings. It was also found to be useful for shortening the time required to reach steady rotation. Further, no rust was generated even in an environment where untreated bearings rust. Therefore, it can be said that the significance of the present invention is extremely large.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view showing a structure of a hydrodynamic bearing used in Examples. 1 ... Housing, 2 ... Shaft, 3 ... Thrust bearing, 4
…… Film, 5 …… Herringbone groove.

Claims (1)

[Claims] 1. A functional group is provided on at least one of opposed surfaces including at least one of the opposed surfaces of a dynamic pressure bearing in which a groove for guiding a fluid in a fixed direction is formed on at least one of opposed surfaces that rotate relative to each other. A hydrodynamic bearing characterized by being coated with a polyfluoroalkyl polymer or a fluoropolyether polymer having a functional group.