JPH11108060A - Bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain satisfactory abrasion characteristics similar to the case adopting a ceramic sintered body alone by coating at least one of sliding surfaces of a rotating member and a fixed member with a hard film selected from chromium oxide, tungsten carbide, chromium carbide. SOLUTION: A rotary shaft 157 of a bearing device is in contact with a pad 153 when the shaft is not rotated. When the rotary shaft 157 is rotated, dynamic pressure is generated between the rotary shaft 157 and the pad 153 due to water as lubricating fluid, or process fluid in the case that a device 150 is arranged on a fluid machine. The rotary shaft 157 is thus held without being contact with the pad 153. A sliding surface of the rotary shaft 157 is made of metal. A base material of the opposed pad is also made of metal. Its surface is coated by chromium oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bearing device, and more particularly to a bearing device suitable for use in a fluid machine such as a pump or a water wheel.

[0002]

2. Description of the Related Art Such a bearing device is required to have good friction resistance and to be able to reduce friction of a rotating system. A water-lubricated bearing device using a rubber bearing or a ceramic sintered body is known.

However, rubber bearings have a problem in wear resistance. In addition, when a rubber bearing is applied to a large machine, there is a problem that the structure becomes complicated.

On the other hand, according to a bearing device using a ceramic sintered body, the structure can be simplified. However, there is a problem that the processing of the ceramic sintered body itself is extremely difficult as compared with a metal material or the like, and the manufacturing cost increases. In particular, in the case of a bearing device having a large diameter, the assembling work becomes very complicated.
Manufacturing costs will increase.

[0005]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned various problems of the prior art, and has a required friction resistance and a function of reducing friction. It is an object of the present invention to provide a bearing device which does not complicate the structure, facilitates the assembling work, and can keep the manufacturing cost low.

[0006]

Means for Solving the Problems As a countermeasure for the above-mentioned problem, the inventors have paid attention to coating a hard coating of a ceramic material on the surface of an inexpensive base material such as a metal and using the coating as a bearing material. . Using a thermal spray coating of a typical metal oxide ceramic material and a thermal spray coating of a metal carbide ceramic material, we conducted various friction and wear experiments in water, and by comparing with the test results of ceramic sintered bodies, The suitability as a material for the water lubricated bearing device was evaluated. As a result, they have found that a ceramic sprayed coating on a rotating member and / or a fixed member made of a metal material or ceramic as a base material can be suitably used as a bearing device.

The bearing device of the present invention has a rotating member fixed to a rotating side, and a fixed member fixed to the fixed side and facing the rotating member. In a bearing device that slides and contacts, at least one of the rotating-side member and the fixed-side member has a sliding surface coated with a hard coating, and the hard coating is formed of chromium oxide (Cr ₂ O ₃ ). It is characterized by being one of tungsten carbide (WC) and chromium carbide (Cr ₃ C ₂ ).

Here, the "rotating member fixed to the rotating side" corresponds to, for example, a rotating shaft, a sleeve fitted to the rotating shaft, and the like. Further, as the "fixed member facing the rotating member", for example, a bearing, particularly,
The contact surface member of the bearing corresponds to this.

In implementing the bearing device of the present invention, it is possible that at least one base material of the rotating side member and the fixed side member is made of a metal material. Of course, the base material of both the rotating side member and the fixed side member can be made of a metal material.

Further, it is possible that at least one of the base material of the rotating side member and the fixed side member is made of ceramics. Also in this case, the base material of both the rotating side member and the fixed side member can be made of ceramics.

In the practice of the present invention, the composition of the hard coating is preferably 99% chromium oxide (99.0% Cr ₂ O ₃ ). The ceramic is silicon carbide (S
It is preferably a sintered body of iC).

Further, a process fluid of a fluid machine provided with the bearing device can be used as a lubricant.

In addition, the bearing device of the present invention can be of a so-called “water lubrication” type. That is, in the case of a so-called water pump, the self-lifting fluid can be used as a lubricant, or water acting as a lubricant can be supplied by a separately provided fresh water supply mechanism.

According to the bearing device of the present invention having the above-described configuration, at least one of the rotating side member and the fixed side member has a sliding surface coated with a hard coating,
Since the hard coating is any of chromium oxide, tungsten carbide, and chromium carbide, the base material is made of a material that is relatively easy to process, such as a metal material, and the sliding surface is coated with the hard coating. It is possible to adopt an easy manufacturing process.

Here, according to experiments by the inventors, particularly when a chromium oxide film is formed, the same good abrasion characteristics as when a ceramic sintered body is used alone can be obtained. Therefore, according to the present invention, a bearing device having the same level of wear resistance as a bearing made of a single ceramic sintered body can be manufactured by a simple manufacturing process.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 8 illustrate a structure of a bearing to which the present invention is applied. 1 and 2 show a structural example of a water-lubricated dynamic journal bearing. In the bearing 150 shown in FIGS. 1 and 2, a rotating shaft 157 (FIG. 2) serving as a rotating member and a fixed member (contact surface member of the bearing) are provided inside a carrier ring 151 functioning as a housing.
And a metal pad 153 that is The inner circumferential surface of the pad 153 in the radial direction is made of chromium oxide (C
r ₂ O ₃ ) (FIG. 1). 1 and 2, reference numeral 152 denotes a pad stop, reference numeral 154 denotes a joint pin, reference numeral 155 denotes a stop pin, and reference numeral 156 denotes a joint bolt.

When the rotating shaft 157 is not rotating,
The rotation shaft 157 is in contact with the pad 153 (more specifically, the chromium oxide film 160 coated on the radially inner peripheral surface of the pad 153). On the other hand, when the rotating shaft 157 rotates, a dynamic pressure is generated between the rotating shaft 157 and the pad 153 by water (a process fluid if the device 150 is provided in a fluid machine) acting as a lubricating fluid. , The rotating shaft 157 is supported without contacting the pad 153.

Here, the sliding surface of the rotating shaft 157 is made of metal, the base material of the facing pad 153 is made of metal, and the surface thereof is coated with chromium oxide. Very good. Here, the pad 153 can be formed of a ceramic such as silicon carbide. Also, in FIG.
However, (the sliding surface of) the rotating shaft 157 may be coated.

3 and 4 show a water lubricated hydrostatic journal bearing. In the bearing 250 shown in FIGS. 3 and 4, the rotating shaft 265 (FIG. 4) as the rotating member and the metal pad 263 and the land 261 as the fixed member (contact surface member of the bearing) are connected to the rotating shaft 265. Sliding when rotating. here,
The radially inner peripheral surfaces of the pad 263 and the land 261 are coated with a coating 270 of chromium oxide (Cr ₂ O ₃ ).

Here, the sliding surface of the rotating shaft 265 is made of metal, the base material of the pad 263 and the land 261 facing each other is metal, and the surfaces thereof are coated with chromium oxide, so that the wear resistance and the wear resistance are improved. The friction characteristics are extremely good. 3 and 4, the pads 263 and the lands 261 can be formed of ceramic such as silicon carbide. Further, the coating 270 may be coated on the sliding surface of the rotating shaft 265. Reference numeral 262 denotes a pocket, and reference numeral 264 denotes a supply hole for supplying a lubricant.

5 and 6 show a water-lubricated hydrodynamic thrust bearing. In the bearing 350 shown in FIGS. 5 and 6, a rotating shaft (not shown) as a rotating member is rotatably supported by a metal pad 372 as a fixed member (contact surface member of the bearing). . On the surface of the pad 372 that slides on the rotation axis, a coating 3 of chromium oxide (Cr ₂ O ₃ ) is provided.
80 are coated.

The sliding surface of the rotating shaft (not shown) is made of metal, the base material of the opposing pad 372 is made of metal, and the sliding surface is coated with a chromium oxide film 380. Is extremely good. FIG.
Also in 6, the pad 372 can be formed of a ceramic such as silicon carbide. Further, a coating surface 380 of chromium oxide may be coated on a sliding surface of a rotating shaft (not shown). Reference numeral 371 denotes a carrier ring, 3
73 is a pad stop, 374 is an end pad stop, 375 is an end pad stop set screw, 376 is a locking member such as a stop key or pin, 377 is an adjust spacer, 378 is an adjust spacer set screw,
379 is a shim.

7 and 8 show a water-lubricated hydrostatic thrust bearing. In the bearing 450 shown in FIGS. 7 and 8, a rotating shaft (not shown) as a rotating member is rotatably supported by a metal pad 483 as a fixed member (contact surface member of the bearing). . The sliding surface of the pad 483 is covered with a coating 490 of chromium oxide (Cr ₂ O ₃ ).

The sliding surface of the rotary shaft (not shown) is made of metal, the base material of the pad 483 for slidingly supporting the metal is metal, and the sliding surface is coated with a chromium oxide film 490. Abrasion and friction characteristics are extremely good. 7 and 8, the pad 483 can be formed of ceramic such as silicon carbide. Further, a coating 490 of chromium oxide may be coated on the sliding surface of the rotating shaft (not shown). Note that reference numeral 381 is a land,
Reference numeral 382 denotes a pocket, and reference numeral 384 denotes a supply hole for supplying a lubricating liquid (water).

Here, in FIG. 1-8, the coating on the sliding surface is exemplified by chromium oxide.
It may be chromium carbide.

The wear characteristics and friction characteristics when chromium oxide, tungsten carbide, and chromium carbide are used as the coating will be discussed below.

FIG. 9 shows an embodiment of the experimental apparatus. Rotating plate 1 made of stainless steel (SUS316L)
Is fixed to the rotating shaft 2 to form one sliding surface. The other sliding surface is formed by fixing the ring-shaped body 3 having the recess 5 formed thereon to the pressing shaft 4 which is provided so as to be movable in the axial direction but is not rotatable. Here, the pressure shaft 4 is configured to apply a load L upward from a pneumatic device (not shown). Further, a torque meter 8 for detecting a change in torque during an experiment is attached to the pressing shaft 4.

A first test material 6 is mounted on the lower surface of the rotating plate 1, and a second test material 7 is mounted on the upper surface of the ring-shaped body 3.
Is attached. The entire experimental apparatus shown in FIG. 9 is configured so that a test material is tested in distilled water filled in a water tank (not shown).

Considering that the material needs good friction and wear characteristics when starting and stopping when solid contact of the bearing material occurs, the friction and wear characteristics of the test material in boundary or mixed lubrication are considered. The comparative evaluation is performed under the following experimental conditions. That is, the peripheral speed is 0.5 m / s,
The bearing pressure starts from 0.1 MPa and is increased by 0.1 MPa every time the sliding surface of the test material travels 1000 m. Then, when the torque suddenly rises while rotating the rotating plate 1 and the damage of the sliding surface reaches the maximum wear depth of 2 μm or more, the experiment is stopped, and the bearing pressure at that time is evaluated as the limit bearing pressure. .

FIG. 10 shows an example of the test material, in which a ceramic sintered body and a ceramic sprayed coating coated on the surface of stainless steel (SUS316L) are shown.

FIG. 11 shows combinations of test materials used in the experiment. Here, No. 1 indicates a combination of ceramic sintered bodies that have been used as water-lubricated bearing materials, and serves as a guide for comparison evaluation.

FIG. 12 shows the experimental results in which the vertical axis indicates the limit bearing pressure (the upward arrow indicates the above), and the horizontal axis indicates the combination number of the test material (see FIG. 11). Here, three sets of experiments were performed only on the test sample with the combination indicated by No. 3. And in the experimental result of the sample of No. 3, there was one set having a limit bearing pressure of 1.0 MPa or more. The sample (or combination) of this number 3 is a combination of samples in which a substrate is coated with a coating,
The limit bearing pressure was the highest.

No. 4 has a high coefficient of friction of about 0.5. In No. 5, when the pressure (corresponding to the bearing pressure) reached 0.6 MPa, there was a sudden increase in torque, and wear increased. But,
At a pressure lower than that, the sliding surface was smooth and the friction coefficient was stable at about 0.1 to 0.2. The samples (or combinations) of Nos. 4 and 5 do not have the abrasion resistance of the combination of the conventional materials indicated by No. 1. However, Nos. 4 and 5 show the problems of the conventional material bearings (that is, the increase in manufacturing cost when the peripheral speed is low or the bearing pressure is low) depending on the operating conditions. This is effective in compensating for the large labor required for the assembly work.

FIG. 13 shows a combination in which the critical bearing pressure is 1.0 MPa or more, the friction coefficient is plotted on the vertical axis, the bearing pressure is plotted on the horizontal axis, and the sample number (number 1-5 described above) is plotted as a parameter. The graph shows the bearing pressure dependence of each friction coefficient, and the friction coefficient is an average of the latter 20% of the running distance at each bearing pressure. In the prior art No. 1, the coefficient of friction increases as the bearing pressure increases. On the other hand, in the combinations indicated by Nos. 2 and 3, whether the friction coefficient is constant even when the bearing pressure increases,
Or, conversely, the frictional property was lowered, and a better friction characteristic than that of the prior art No. 1 was obtained.

Although not shown in FIG. 13, for Nos. 4 and 5, the frictional properties comparable to the combination of the conventional materials indicated by No. 1 are not obtained. But,
Depending on the operating conditions, the samples or combinations of Nos. 4 and 5 are effective in compensating for the disadvantages of the No. 1 conventional material.

FIGS. 14, 15 and 16 show the cross-sectional curves of the sliding surface after the experiment for each of the combination numbers 1, 2, and 3 of the test materials. In each case, the amount of wear was small and the sliding surface was smooth.

From the above experimental results, it was found that the combination of chromium oxide film (Cr ₂ O ₃ film) / Cr ₂ O ₃ film of combination No. 3 was good. It has been found that this is a result of the roughness of the sliding surface being reduced and the smooth surface being formed due to the effect of the transfer of the mating material between the two friction materials.

However, it is also noted that coating with tungsten carbide and chromium carbide can be performed.

[0039]

According to the present invention, a bearing device having good wear characteristics or wear resistance comparable to that of a conventional bearing device using a ceramic sintered body alone is based on a material which is relatively easy to process. It can be manufactured by a process of forming a material and coating a sliding surface with a hard coating. And, since it is easy to manufacture and it is not necessary to manufacture all the members as a single ceramic sintered body, bearings for large fluid machines such as water turbines and water pumps can be easily assembled and provided at low cost. .

[Brief description of the drawings]

FIG. 1 is a front view showing a water-lubricated dynamic pressure journal bearing to which the present invention is applied.

FIG. 2 is a side view of the water-lubricated dynamic pressure journal bearing of FIG. 1;

FIG. 3 is a development view showing a water-lubricated hydrostatic journal bearing to which the present invention is applied.

FIG. 4 is a front view of the water-lubricated hydrostatic journal bearing of FIG. 3;

FIG. 5 is a plan view showing a water-lubricated dynamic thrust bearing to which the present invention is applied.

FIG. 6 is a sectional view taken along line AA of FIG. 5;

FIG. 7 is a plan view showing a water-lubricated hydrostatic thrust bearing to which the present invention is applied.

FIG. 8 is a sectional view of the water-lubricated hydrostatic thrust bearing of FIG. 7;

FIG. 9 is a side view showing a main part of one experimental device of the present invention.

FIG. 10 shows an example of a test material.

FIG. 11 is a diagram showing an example of combinations of test materials.

FIG. 12 is a diagram showing experimental results by a limit bearing pressure and a test material number.

FIG. 13 is a view showing experimental results in a relationship between a friction coefficient and a bearing pressure.

FIG. 14 is a diagram showing a slip surface cross-sectional curve of test number 1 after the experiment.

FIG. 15 is a diagram showing a slip surface cross-sectional curve of Test No. 2 after the experiment.

FIG. 16 is a diagram showing a slide surface cross-sectional curve of test number 3 after the experiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rotating plate 2 ... Rotating shaft 3 ... Ring-shaped body 4 ... Pressurizing shaft 5 ... Recess 6 ... First test material 7 ... Second test Material 8: Torque meter 157, 265: Rotating shaft 153, 263, 372, 483: Pad 160, 270, 380, 490: Chromium oxide film

Claims (6)

[Claims] 1. A rotating member fixed to a rotating side, and a fixed member fixed to a fixed side and facing the rotating member, wherein the rotating member and the fixed member slide. In the contact bearing device, at least one of the rotating-side member and the fixed-side member has a sliding surface coated with a hard coating, and the hard coating is formed of chromium oxide, tungsten carbide,
A bearing device characterized by being one of chromium carbide. 2. The bearing device according to claim 1, wherein at least one base material of the rotating side member and the fixed side member is a metal material. 3. The bearing device according to claim 1, wherein at least one base material of the rotating side member and the fixed side member is made of ceramic. 4. The bearing device according to claim 1, wherein the composition of the hard coating is 99% chromium oxide. 5. The bearing device according to claim 3, wherein the ceramic is a sintered body of silicon carbide. 6. The bearing device according to claim 1, wherein a process fluid of a fluid machine provided with the bearing device is used as a lubricant.