JP2000145785A - Thrust bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage, separation and electrolytic corrosion of the slide surface by providing resin having different properties from the slide part side into a plurality of layers, arranging resin having high electric insulating performance to a second layer, and impregnating and bonding the resin of the second layer to a sintered body fixed to a back metal by heating and pressurizing, in the bonding of a bearing pad back metal and a resin slide member. SOLUTION: A thrust bearing pad 4 is constituted of a PEEK base resin 5 for forming a first layer as a slide member, an electric insulating resin 6 of a second layer, and a sintered body 8 as a bonding medium for bonding a back metal 7 as a strength member to the resin layer 6. The resin 6 and the resin 5 differ in the melting point, and resin having the similar thermal expansion coefficient and bending strength, for instant, polyphenylene sulfide or polyethylene terephthalate is preferable. The resin 6 is impregnated in an air hole part 9 of the sintered body 8, has a layer for preventing the resin 5 and the sintered body 8 from being brought into direct-contact with each other, and forms an axial current shutting off zone 6'. By this structure, damage of the slide surface or separation of the resin slide member does not occur even if large load, starting and stopping are repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a thrust bearing device having a fan-shaped bearing pad radially arranged around a rotating body, such as a vertical turbine generator, and more particularly to a bearing. The present invention relates to a thrust bearing device in which a resin-based sliding member is used as a pad sliding member.

[0002]

2. Description of the Related Art In recent years, hydroelectric power generation facilities have tended to increase in capacity and speed as represented by pumped-storage generators in view of the location conditions of power plants and construction costs. The thrust bearing used in the vertical shaft turbine generator supports not only the weight of the rotating body of the turbine and the generator but also the water thrust applied to the turbine. For large capacity machines, the thrust bearing is 3000
It will support loads of up to 4000 tons, and its peripheral speed will reach as high as 40 to 50 m / sec, and bearing losses will tend to increase further.

In pumped storage generators, water used for daytime power generation and stored in a lower pond is pumped to an upper pond at night so that the pump is always started and stopped on a daily basis, and operating conditions are severe. It has become something. For these reasons, these thrust bearings are required to have a high reliability which sufficiently satisfies all operating conditions and enables stable power supply for a long period of time.

[0004] By the way, as a sliding material of this bearing,
Traditionally, tin-based white metal has been used for many years. However, the melting point of white metal is 24
Because the high temperature fatigue strength is around 0 ° C and the high temperature fatigue strength is low, for example, in the case of a type of bearing that repeatedly starts and stops with high speed and high load, such as a pumped generator, an oil film is not sufficiently formed on the sliding surface. When used for a long period of time, the sliding surface may be damaged due to low cycle fatigue and the like, and may eventually develop to burnout of the bearing.

On the other hand, recently, engineering plastic materials having low friction and heat resistance have attracted attention as sliding materials. In particular, thermoplastic resin polytetrafluoroethylene (hereinafter referred to as PTFE) has been used as a sliding member for bearings of large rotating machines. ), Polyetheretherketone (hereinafter referred to as PEEK), and glass fiber, carbon fiber, graphite, molybdenum disulfide, etc. added to improve mechanical strength, sliding characteristics and wear resistance. Polymer composite resin materials have begun to be used for thrust bearings of turbine generators.

When such a resin is used for a thrust bearing of a large-sized rotating machine, a high load is imposed on the thrust bearing, so that a resin material is always integrally bonded to a high-rigidity steel back plate (strength member). ing. Therefore, if the adhesion strength between the two members is insufficient, the resin sliding portion peels off during operation, which may cause a fatal accident. Therefore, the joining technique between the resin material and the strength member is an essential issue. I have.

Japanese Patent Application Laid-Open Nos. 59-2839, 59-1882843 and 63-297457 disclose a method of bonding this resin material to a strength member. A method is disclosed in which a layer is formed, and a surface thereof is impregnated with and coated with a PEEK composite composition to form a sliding member.

In Japanese Patent Application Laid-Open No. 5-296235, a wire member such as a wire mesh or a coil bobbin made of copper or a copper alloy material is joined to the upper surface of an iron-based base metal by silver brazing or the like. A method is disclosed in which tetrafluoroethylene (PTFE) material or the like is melted at a high temperature, filled and pressurized, and the PTFE material and the iron-based base are integrally bonded.

[0009]

In the above-mentioned prior art, for example, in the techniques disclosed in JP-A-59-2839, JP-A-59-182843 and JP-A-63-297457, carbon Since a composition comprising a mixture of fiber, PTFE, bronze, graphite, and the like and PEEK is formed by impregnating the uneven surface of the porous layer with pressure, a sufficient bonding strength can be obtained by the anchor effect. However, although pure PEEK resin itself is an electrical insulator, conductive carbon fiber, graphite, bronze, and the like are used as additives to improve sliding characteristics and wear resistance. In some cases, a shaft current is generated inside the bearing from the rotating side, causing electrolytic corrosion and damaging the bearing sliding surface.

In the technique disclosed in Japanese Patent Application Laid-Open No. 5-296235, PTFE is melted at a high temperature and bonded to a space of a linear member fixed to a base with a silver solder, so that sufficient adhesion strength is obtained. It is possible, however, to use PTF
Since both E and the linear member are elastic bodies, when supporting a large load, deformation such as distortion may occur. Therefore, it is necessary to manufacture in consideration of this point.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method of manufacturing a resin sliding material even when a heavy load is applied and start and stop are repeated. An object of the present invention is to provide a thrust bearing device of this kind which does not cause peeling and prevents electric corrosion by interrupting a shaft current, can sufficiently exhibit lubrication characteristics of a resin material, and has high reliability.

[0012]

That is, the present invention relates to a method for manufacturing a thrust bearing in which a resin-based sliding member is fixed to a sliding-side surface of a backing metal. In joining the moving member, a resin-based sliding member is provided with a resin having different physical properties in a first layer, a second layer and a plurality of layers from the sliding portion side, and the resin of the second layer is electrically insulating. A high current resin is formed to form an axial current cutoff zone, and the sintered body fixed to the back metal is impregnated with the resin of the second layer by heating and pressing to be bonded. The purpose of this period is to be achieved.

The resin-based sliding member formed in a plurality of layers is selected from resins having different melting points, and the melting point of the resin forming the first layer is set to be higher than that of the second layer. The thermal expansion coefficient, the bending strength, and the like are almost equal to each other.

That is, in the thrust bearing device formed as described above, and in the manufacturing method, when the back metal is connected to the resin-based sliding member, the resin forming the first layer and the resin forming the second layer is connected. Is bonded by appropriately applying pressure in a temperature range exceeding the melting point of the resin of the second layer and not more than the melting point of the resin of the first layer. The resin material bonded in this manner is laminated on the sintered body fixed to the back metal, held in a temperature range exceeding the melting point of the resin of the second layer, and pressed with an appropriate load in the same manner as described above. The resin on the sintered body is melted by heating and pressurizing and sufficiently impregnated in the pores, so that the bonding effect can be enhanced by the anchor effect.

Further, by combining resins having different physical properties, not only the sliding characteristics, abrasion resistance, mechanical strength, etc. are improved, but also the occurrence of electrolytic corrosion can be prevented beforehand by forming an axial current cutoff zone. Things.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 shows the thrust bearing device and the bearing pad. 1 is a rotating shaft of a water turbine generator, for example, and 14 is an oil tank and a 4 thrust bearing pad.

The thrust bearing device calculates the total weight of the rotating body composed of the thrust collar 2 and the thrust runner 3 fixed to the rotating shaft 1 and the total weight of the water thrust applied to the water turbine during operation. The lubricating oil 16 is supported by a plurality of radially arranged thrust bearing pads 4. The thrust bearing pad 4 is swingably supported by a spherical pivot 17 and is positioned by a detent 13.

An oil dam 15 is provided at the innermost periphery of the oil tank 14 to store the lubricating oil 16 and prevent oil leakage to the outside. The lubricating oil 16 is configured to circulate and cool through a cooling device (not shown) for cooling the lubricating oil 16 and a supply / discharge oil pipe (not shown).

FIG. 1B is a perspective view of a thrust bearing pad 4 to which a PEEK-based resin is applied as a sliding material. The thrust bearing pad 4 is made of PE forming a first layer which is a sliding member.
It comprises an EK-based resin 5 and an electrically insulating resin 6 of a second layer, a backing metal 7 as a strength member, and a sintered body 8 of a bonding medium for bonding the resin layer and the backing metal 7.

The electrically insulating resin 6 forming the second layer is
A resin having a different melting point from the first-layer PEEK-based resin 5 and having a similar thermal expansion coefficient and bending strength, for example, PPS.
(Polyphenylene sulfide), PET (polyethylene terephthalate) and the like are desirable.

FIG. 2 is a vertical cross-sectional view of the thrust bearing pad 4.
And 5 layers of PEEK resin and sintered body 8
Has a layer which does not directly contact with the shaft and forms an axial current cutoff zone 6 '.

FIGS. 3A and 3B show the joining state of the thrust bearing pad 4, wherein (a) the joining between the back metal and the sintered body, and (b) the PEEK.
It is sectional drawing which shows the joining state of a base resin and an electrically insulating resin, and the joining state of (c) a sintered compact and an electrically insulating resin.

First, when the back metal and the sintered body are joined, (a)
, And a low melting point insert material (for example, silver low) is inserted between the sintered body 8 and the back metal 7, and is fused by heating. As the insert material, any of a thin plate and a powder can be used, but it is preferable to make the insert material as thin as possible in order to reduce the variation in bonding strength. Also, during heating, the sintered body 8 on the dedicated table 10 and the back metal 7 are prevented from slipping by the side plate 11 so as not to slip.

In the case of joining the PEEK-based resin 5 and the electrically insulating resin 6, the state (b) is set in the same manner as described above.
The heating temperature at this time is controlled to a temperature higher than the melting point of the electrically insulating resin 6 and lower than or equal to the melting point of the PEEK-based resin 5, and an appropriate load is applied for joining.

As described above, since the joining is performed at a temperature equal to or higher than the melting point of the resin, if the melting points of the two resins 5 are the same, the resin flows at the time of heating, and voids are generated by the gas dissolved in the resin. It is not advisable to reduce the strength of the resin.

Since the PEEK-based resin 5 slides on the thrust runner 3, heat is generated by the shear friction effect during operation of the main engine, and the bearing temperature rises. In addition, since it is deformed by bending to apply a load, bending stress occurs together with thermal stress at the joint between the PEEK-based resin 5 and the electrically insulating resin 6, and peeling due to fatigue easily occurs in long-term use. Become. For this reason, when selecting the material of the electrically insulating resin 6 with respect to the PEEK-based resin 5, it is desirable to select a material whose fiber expansion coefficient and bending strength are similar.

Next, the resin pieces thus formed in two layers are laminated on the sintered body 8 joined to the back metal 7 and set in the state shown in FIG. The heating temperature in this case is also similar to the above,
The temperature is controlled to be higher than the melting point of the electrically insulating resin 6 and equal to or lower than the melting point of the PEEK-based resin 5.

Then, the PEEK-based resin 5 is pressed with an appropriate load from above from the upper portion through the pressing piece 12 as shown by the arrow. The resin 6 on the sintered body 8 is melted by heating and pressurizing, and is impregnated into the pores 9 of the sintered body 8 and forms an axial current cutoff zone 6 '.

When the pores 9 are impregnated with a resin, it is particularly difficult to release the gas dissolved in the resin, which often causes voids and significantly lowers the bonding strength. Therefore, in order to improve the bonding strength, it is necessary to sufficiently consider and set parameters such as the viscosity of the molten resin, the load, the roughness of the pores 9 and the speed at the time of loading.

In the case of joining by heating and pressurizing, the resin 6 is melted and impregnated into the pores 9 of the sintered body 8, but a part of the resin 6 flows from the side end. For this reason, the dedicated table 10
A release agent is applied to the surface of the side plate 11 in advance to facilitate removal.

Generally, a thermoplastic polymer resin is an electric insulator. However, when used as a sliding material for a large rotating machine such as a water turbine generator, carbon fiber, graphite, or the like is usually used.
It is indispensable to add a conductive substance such as molybdenum disulfide to improve mechanical strength, sliding characteristics, abrasion resistance, and the like, and the amount of the addition is considerable. For example, PEEK
In the case of a resin, the electrical resistivity of pure PEEK resin is about 10 ^{15 to 17} Ω · cm in the catalog value, but when 30% of carbon fiber is added, the electrical resistivity decreases to 1/3 or less and becomes a semiconductor. Will be lost.

In the case of the turbine generator, when an axial current flows through the thrust bearing 4 while the main engine is operating, sparks and arcs are generated through a thin lubricating oil film at a contact portion between the thrust runner 3 and the thrust bearing 4 on the sliding surface. When the sliding surface is locally melted and operated for a long period of time in this state, the oil temperature rises, causing the sliding surface to be damaged and eventually causing the thrust bearing 4 to burn out.

In order to prevent such damage to the thrust bearing 4 due to electrolytic corrosion, it is essential to cut off the shaft current in the electric circuit, and the treatment is provided on the fixed side rather than the rotating side. Usually, a countermeasure is taken by installing a double insulator such as a bakelite plate at the joint of the oil tank 14 or at the end of the bearing frame.

In the present invention, by combining a PEEK-based resin 5 which is converted into a semiconductor with an additive and an electrically insulating resin 6, a resin layer having improved slidability and excellent insulation is formed. It is. For this reason, the axial current can be reliably shut off in the bearing pad 4 without complicating the structure, so that a bakelite plate or the like which has been used to prevent the axial current is unnecessary, and the cost can be reduced. .

In the embodiment described above, the resin material forming the sliding surface of the thrust bearing pad 4 is made of carbon fiber,
It is a thermoplastic composition to which graphite, bronze, glass fiber, fluorine compound, etc. are appropriately added according to the purpose. It has excellent abrasion resistance and low friction coefficient compared to white metal, so it is stable even under high surface pressure. A fluid lubrication effect is obtained.
In addition, even when the oil film thickness in the operating state at the time of starting / stopping is extremely small, a good lubricating state can be maintained without causing surface roughness or wear. Due to the self-lubricating effect peculiar to the resin material, the supply of static pressure oil to the sliding surface by a high-pressure oil pump (oil lifter device), which has been indispensable at the time of starting and stopping, has become unnecessary. Simplification and maintenance and management become easier.

Further, the melting point of white metal is about 240
° C, while about 100 ° C for PEEK resin.
℃ and excellent in high temperature fatigue strength. Even if the sliding surface is operated for a long time in a state where an oil film is not sufficiently formed, the sliding surface is not damaged.

On the other hand, the end of the thrust bearing pad 4 is supported by a pivot 17 and is capable of tilting in the circumferential direction and the radial direction. It can be supported without contact. However, during rotation, the sliding surface generates heat due to the shear friction action of the lubricating oil 16, causing a temperature difference in the thickness direction of the bearing pad 4,
Due to this temperature difference, the bearing pad 4 causes a convex deformation. This deformation occurs in both the circumferential direction and the radial direction. In particular, the amount of deformation in the radial direction decreases the region where the oil film pressure is generated, so that the load resistance is greatly reduced.

However, the thermal conductivity of the resin material is smaller than 1/200 or less than that of the white metal, so that the heat insulating effect to the back metal 7 acts greatly, and the thrust bearing pad 4
Can minimize thermal deformation. Therefore, since the amount of deformation can be suppressed to a small value, an appropriate oil film pressure distribution is formed on the sliding surface of the bearing pad 4 and the load resistance is not impaired.

[0039]

As described above, according to the present invention, even if a heavy load is applied and the start / stop operation is repeated, the sliding surface is damaged and the resin sliding material is separated. Thus, the lubrication characteristics of the resin material can be sufficiently exerted, and a highly reliable thrust bearing device of this type can be obtained.

[Brief description of the drawings]

1 (a) and 1 (b) are a longitudinal sectional view and a perspective view of a bearing pad showing an embodiment of a thrust bearing device of the present invention.

FIG. 2 is a longitudinal sectional view of a thrust bearing pad.

FIGS. 3 (a) and 3 (b) are cross-sectional views showing a state of connection of a thrust bearing pad.

[Explanation of Signs] 1 ... rotating shaft, 2 ... thrust collar, 3 ... thrust runner,
4: thrust bearing pad, 5: PEEK resin sliding material,
6 ... electrical insulating resin, 6 '... shaft current cutoff band, 7 ... backing metal, 8 ... sintered body, 9 ... pores, 10 ... dedicated stand, 11 ... side plate, 12 ... press piece, 13 ... detent , 14 ... oil tank, 15 ... oil dam, 16 ... lubricating oil, 17 ... pivot.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomoaki Inoue 502 Kandachi-cho, Tsuchiura-shi, Ibaraki F-term in Mechanical Research Laboratory, Hitachi, Ltd. BA15 DA02 NA02 QA05 SB19 SC12 SC20

Claims (1)

[Claims] In a thrust bearing manufacturing method in which a resin-based sliding member is fixed to a sliding-side surface of a backing metal, when the backing metal of the bearing pad and the resin-based sliding member are joined, The resin-based sliding member is provided with a resin having different physical properties in a first layer and a second layer from the sliding portion side as a back layer. A thrust bearing device, wherein a current cutoff zone is formed, and the sintered body fixed to the back metal is impregnated with the resin of the second layer by heating and pressing to join the thrust bearing.