JP2002106552A - Thrust bearing device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thrust bearing device having low starting coefficient of friction, and excellent abrasion resistance and durability. SOLUTION: A rotating runner is fitted to a rotation shaft via a shaft collar. A bearing pad is provided in contact with a slide surface layer of the rotating runner. In the thrust bearing device supported by a support device and disposed inside an oil reservoir, the bearing pad has oil retainer grooves of 15-30 pieces/25.4 mm2 on the slide surface. The dam function of 70% or more in the depth of the oil retainer groove is provided between the oil retainer grooves. The variance in size of the groove is accurate to within ±10%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thrust bearing device for supporting a rotating shaft load, such as a vertical shaft turbine generator, and more particularly to a rotating torque loss reduction at start-up operation, an improvement in wear characteristics, and excellent running durability. It relates to a thrust bearing device.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing the construction of a thrust bearing device for supporting a large, high-load, high-speed rotating body such as a vertical turbine generator with high accuracy. Turbine generator has a bearing load of 3000 to 40
00 tons, the peripheral speed reaches 40 to 50 m / s, the bearing loss reaches 3000 to 4000 kW, and the generated loss per unit area becomes very large.

[0003] Therefore, reduction of friction loss, improvement of abrasion resistance, and prevention of pad surface damage are demanded from the viewpoints of the operation efficiency of the rotation function and the extension of the service life guaranteed for durability.

As a countermeasure against these problems, a structure in which a soft alloy such as tin or lead is welded to the surface layer of the bearing pad shown in FIG. 1 reduces the sliding area of the surface layer and increases the load per unit area. A small high surface pressure bearing device is used.

[0005] The small high-surface-pressure bearing device has an unavoidable mechanical problem such as an incompletely formed initial oil film formed on the bearing pad surface or a lack thereof when the operation is started or stopped or at low speed rotation.

[0006] Further, in a small- and medium-capacity generator, an air-cooled bearing for cooling a bearing lubricating oil using a fan without using cooling water is used. When this air-cooled bearing is used, the temperature of the lubricating oil in the bearing tank rises and the viscosity of the lubricating oil decreases, making it more difficult to form a lubricating oil film during low-speed rotation than when using cooling water. Become. Therefore, if a high surface pressure design is used to reduce the generation loss or the starting torque, the lubricating oil film will not be formed sufficiently and the sliding surfaces will come into contact with each other, causing abnormal expansion of the roughness of the sliding surfaces and overheating. This may lead to generation, seizure, or sudden stop of rotation.

[0007] Therefore, measures to reduce the loss by downsizing and increasing the surface pressure are as follows: oil retaining groove processing (cutting processing), improvement of the flatness and roughness accuracy of the bearing pad surface, and design techniques such as load supporting mechanism or There is prevention of deflection of the sliding surface by modification of the cooling method. Of these, oil retaining groove processing is the most effective.

[0008] In order to enhance the oil retaining effect at the time of starting, there has been proposed a method of machining an oil retaining groove on a sliding surface of a bearing pad using an automatic processing machine (a scraping robot).

[0009] On the other hand, small high surface pressure bearing devices are often provided with a dedicated oil lifter device in order to reduce torque loss at the time of starting operation. However, although this method is effective in reducing the starting torque, it has a problem that a high-pressure-resistant hydraulic device (pump), complicated piping, and an operation control system are essential and expensive.

[0010]

As described above, in order to reduce the bearing loss, reduce the starting torque, and improve the durability at the time of starting and stopping by reducing the size of the thrust bearing device and increasing the surface pressure, automatic machining is performed. An oil retaining groove machining by a machine is disclosed.
However, in this technique, when machining oil retaining grooves, it is necessary to make the number of oil retaining grooves per unit area appropriate and specify an optimal machining method.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thrust bearing device in which a rotation torque loss at the time of a start-up operation based on a heavy-weight rotating body load is reduced, wear characteristics are improved, and driving durability is improved.

[0012]

SUMMARY OF THE INVENTION The above-mentioned problems are solved by the present invention. The gist is as follows: (1) A rotating runner is fixed to a rotating shaft via a shaft collar, a bearing pad is provided in contact with a sliding surface layer of the rotating runner, and the bearing pad is supported by a support device. In the bearing device, the bearing pad has 15 to 30 oil retaining grooves / (inch) ^{2 on a} sliding surface, and has a dam function of 70% or more of the depth of the oil retaining groove between the oil retaining grooves. And a thrust bearing device in which the variation in the size of the oil retaining groove is within ± 10%. The surface of the bearing pad has a sliding surface layer mainly composed of tin or lead, and an oil retaining groove is formed on the sliding surface by an automatic processing machine (a scraping robot).
It is preferred to be processed by. (2) Manufacture of a thrust bearing device in which a rotating runner is fixed to a rotating shaft via a shaft collar, a bearing pad is provided in contact with a sliding surface layer of the rotating runner, and the bearing pad is supported by a supporting device. In the method, an oil retaining groove is formed on a sliding surface of the bearing pad by using an automatic processing machine (a scraping robot).
Thrust having 0 / (inch) ^{2 and} having a dam function of 70% or more of the depth of the oil retaining groove between the oil retaining grooves and making the size variation of the oil retaining grooves within ± 10% It is a manufacturing method of a bearing device.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. FIG. 1 is a perspective view of a general thrust bearing pad. The thrust bearing pad has a structure in which a surface layer 1 made of a metallic material is formed on the surface of one main surface of a back metal 3 of the bearing pad, and an oil retaining groove 2 is formed on the surface layer 1 by scraping.

The surface layer is a sliding surface with the rotating runner 4, and the surface layer 1 is mainly made of white metal.

FIG. 2 is a longitudinal sectional view of a main part of the thrust bearing device of the turbine generator. The rotating runner 4 is fixed to the rotating shaft 6 extending in the vertical direction via a shaft collar 9. A bearing pad 5 is provided facing the rotating runner 4, and the pad 5 is supported by supporting devices 7 and 8. These bearings are arranged in a sump 11.

FIG. 3 shows the state (shape) of the cross section of the processed part when the sliding surface of the bearing pad shown in FIG. In the manual operation, the processed portion has a sharp finish, which reduces the oil retaining effect of the thrust bearing pad when the generator is started / stopped, and reduces the thickness of the lubricating oil film formed during operation. For this reason, the performance may be lower than that of the bearing pad having no oil retaining groove on the sliding surface. On the other hand, the machined part has an arc-shaped cross section, which enhances the oil retaining effect of the thrust bearing pad when the generator is started and stopped, and has an effect on the formation of a lubricating oil film during operation. Without affecting, an ideal shape can be formed. In order to maintain the shape of the processed portion and to reduce the variation in the size of the oil retaining groove, it is necessary to appropriately shape the processing jig.

When processing the oil retaining groove using an automatic processing machine, a processing jig having an arc-shaped tip is used. If this arc radius is large, the oil retaining groove per one becomes large, the shape of the oil retaining groove after processing becomes acute, and the oil retaining effect is reduced. Further, the variation in the size of the oil retaining groove is ± 20%. If the arc radius is small, the finish after machining is improved, but the number of oil retaining grooves increases and the machining time becomes longer.

As a result of studying the optimum value of the arc radius, the inventors have found that a radius of 80 to 120 mm is the optimum value. Thereby, an oil retaining groove having an ideal shape can be formed, and a variation in the size can be suppressed to within ± 10%, and the oil retaining effect can be increased.

Further, as a result of studying the density of the oil retaining grooves, if the number of the oil retaining grooves is small, the total amount of oil retained in the entire pad is reduced, and the effect of providing the oil retaining grooves is significantly reduced. If the number of oil retaining grooves is too large, adjacent grooves come into contact with each other, so that the substantial depth of the oil retaining grooves is reduced and the oil retaining effect is reduced. For this reason, it becomes impossible to reduce the friction coefficient at the time of starting and to improve the durability.

FIG. 4 shows the relationship between the density of the oil retaining grooves (the number of oil retaining grooves) and the coefficient of friction (at the time of startup and at the time of steady operation). The density of the oil retaining grooves was represented by the number of oil retaining grooves per square inch. The coefficient of friction at start-up shows a tendency to decrease from 15 to 28 oil retaining grooves, and increases when the number exceeds 30. This is because adjacent oil retaining grooves come into contact with each other and the actual depth of the oil retaining grooves decreases. For this reason, the amount of oil retained in the oil retaining groove decreases, and the coefficient of friction tends to increase.

In addition, the coefficient of friction during operation is determined by the number of oil retaining grooves being three.
If the number exceeds zero, turbulence is generated on the sliding surface and increases. This causes a decrease in the thickness of the lubricating oil film and an increase in the oil film temperature.
Attention was paid to the substantial depth of the oil retaining groove. The solid line in FIG. 4 does not specify the actual oil retaining groove height when adjacent oil retaining grooves overlap.

FIG. 5 shows the relationship between the substantial oil retaining groove height and the oil retaining groove depth. The starting friction coefficient and the operating friction coefficient when the actual oil retaining groove height is 70% or more of the oil retaining groove depth are shown by broken lines in FIG. From this, it is understood that both the starting friction coefficient and the operating friction coefficient are improved, the oil retaining effect at the time of starting is enhanced, and the flow of the oil film during the operation is not affected.

Therefore, when the oil retaining grooves are machined by using an automatic processing machine, the number of oil retaining grooves per unit area (per 1 inch square) is set to 15 to 30, and the substantial oil retaining groove height is further increased. To 70% or more of the oil retaining groove depth, the object of the present invention can be achieved.

Further, in the case where the pad surface has an oil retaining groove formed in an ideal shape in the repeated start and stop operation, abnormal wear is prevented by lubricating oil filled in the oil retaining groove, and the durability is improved. Also contributes.

An example of actual processing is shown below. The shape of the oil retaining groove is an ellipse having a long side of 6 mm and a short side of 5.5 mm, and the incident angle of the processing jig is adjusted so that the depth becomes 0.1 mm. The feed pitch of the processing jig is 6 mm in the circumferential direction and 6.2 in the radial direction.
In the case of 5 mm, 25 oil retaining grooves are machined in a square of 1 inch (25.4 mm), and since they do not contact adjacent oil retaining grooves, the actual oil retaining groove height is the same as the oil retaining groove depth and sufficient oil retaining grooves are provided. An oil effect is obtained.

[0026]

As described above, in the thrust bearing, the size and shape of the oil retaining groove are specified and formed by machining on the surface of the bearing pad to enhance the oil retaining effect during stoppage. Prevents decrease in oil film thickness during operation, keeps lubricating oil on the sliding surface stably from start-up to steady operation and stop, abnormal wear of the sliding surface, heating and seizure of the sliding surface Solve the phenomenon. Further, it is possible to achieve a reduction in torque loss at the start of operation, an improvement in wear resistance, and an improvement in durability. By reducing the friction coefficient at the time of starting operation, the bearing pad can be downsized, the surface pressure can be increased to 1.3 times, and the loss can be reduced.

Further, according to the present invention, there is no need for a hydraulic power source device which requires a complicated and expensive auxiliary equipment such as an oil lifter device. Therefore, the operation control system can be simplified by eliminating the auxiliary equipment, and the effect of reducing plant operation costs can be obtained.

Furthermore, the processing of the oil retaining grooves by the automatic processing machine unifies the processing shape, and enables ideal oil retaining grooves to enhance the oil retaining effect, and has a low starting friction coefficient, excellent wear resistance and excellent durability. Provided is a method for manufacturing a sliding member.

[Brief description of the drawings]

FIG. 1 is a perspective view of a pad shape for a thrust bearing.

FIG. 2 is a main part structural view of a turbine generator thrust bearing device.

FIG. 3 is a comparison diagram of oil retaining groove shapes at the time of manual work and machining.

FIG. 4 is a graph showing the tendency of the coefficient of friction and the density of oil retaining grooves.

FIG. 5 is a relationship diagram between the substantial oil retaining groove height and the oil retaining groove depth.

[Explanation of symbols]

1. Surface layer of bearing pad (sliding surface layer) 2. Oil retaining groove 3.
... bearing pad back metal, 4 ... rotating runner, 5 ... bearing pad, 6 ... rotating shaft, 7 ... supporting device, 8 ... supporting device, 9 ... shaft collar, 10 ... guide bearing, 11 ... oil reservoir.

Continuation of the front page F term (reference) 3J011 AA06 AA10 AA20 BA15 CA01 DA02 JA02 KA03 MA04 NA02 PA02 5H605 BB01 CC04 EB02 EB21

Claims (3)

[Claims] A thrust bearing device comprising: a rotary runner fixed to a rotary shaft via a shaft collar; a bearing pad provided in contact with a sliding surface layer of the rotary runner; and the bearing pad supported by a support device. Wherein the bearing pad has 15 to 30 oil retaining grooves / (inch) ^{2 on a} sliding surface, and has a dam function of 70% or more of the depth of the oil retaining groove between the oil retaining grooves, ± 1 variation in oil retention groove size
A thrust bearing device characterized by being within 0%. 2. The bearing pad according to claim 1, wherein the surface of the bearing pad has a sliding surface layer containing tin or lead as a main component, and an oil retaining groove is formed on the sliding surface by an automatic processing machine (a scraping robot). A thrust bearing device comprising: 3. A thrust bearing device wherein a rotary runner is fixed to a rotary shaft via a shaft collar, and a bearing pad is provided in contact with a sliding surface layer of the rotary runner, and the bearing pad is supported by a support device. In the manufacturing method of
An oil retaining groove is formed on the sliding surface of the bearing pad by using an automatic processing machine (a scraping robot).
5 to 30 pieces / (inch) ^2, having a dam function of 70% or more of the depth of the oil retaining groove between the oil retaining grooves, and keeping the size variation of the oil retaining groove within ± 10%. A method of manufacturing a thrust bearing device.