CN116710657A

CN116710657A - Sliding bearing, sliding bearing device and pump

Info

Publication number: CN116710657A
Application number: CN202180089421.4A
Authority: CN
Inventors: 金成夏; 杉山宪一; 小宫真
Original assignee: Ebara Corp
Current assignee: Ebara Corp
Priority date: 2021-01-06
Filing date: 2021-10-19
Publication date: 2023-09-05
Also published as: WO2022149329A1; JP7543147B2; JP2021060122A

Abstract

Provided is a slide bearing excellent in slurry abrasion resistance when operated in water (slurry) containing foreign matter such as sand, and a pump provided with the slide bearing device. The sliding bearing is formed from a resin composition containing aromatic polyether ketone, a fluororesin, boron nitride, carbon fibers, graphite and unavoidable impurities, wherein the content of graphite is 5 mass% or less (including 0 mass%) relative to the resin composition, the total content of boron nitride, carbon fibers and graphite is 30 mass% or less, and the area ratio of carbon fibers on the sliding surface of the sliding bearing is less than 10%, wherein the area ratio of carbon fibers is an average area ratio obtained by performing image processing on a portion having an observation field of view of 589 [ mu ] m×442 [ mu ] m based on an optical microscope (500 times) for any 5 parts of a sample piece cut from the sliding surface of the sliding bearing, and from the area of a region having a brightness of 75% or more in an HSB color space.

Description

Sliding bearing, sliding bearing device and pump

Technical Field

The present invention relates to a slide bearing suitable for use as a radial bearing of a rotary machine such as a pump, a slide bearing device provided with the slide bearing, and a pump provided with the slide bearing device.

Background

In a case where a slide bearing device having a slide bearing made of a resin material is used in a pump or the like, it is necessary to consider that foreign matters such as sand are mixed in water treated by the pump or the like, and SiO having a large hardness is considered as a main component of the foreign matters ₂ And a phenomenon that the sliding surface of the bearing is invaded to abrade the resin material. That is, in the operation of a pump or the like in water mixed with foreign matter, it is necessary to consider the problems of an increase in the wear amount of a sliding bearing made of resin and a reduction in the bearing life.

Therefore, a resin material for a sliding bearing of a sliding bearing device is required to be formed of SiO ₂ The wear rate is low when running in the slurry.

On the other hand, in a vertical pump or the like, the sliding surface of the bearing is not necessarily operated in water, and may be operated in the atmosphere as in the management operation or the standby operation in advance, that is, may be operated under a dry condition in which the sliding surface of the bearing of the sliding bearing device is exposed to the atmosphere. When the slide bearing apparatus is operated under dry conditions, there is a problem in that the temperature of the resin material on the sliding surface of the bearing increases due to heat generation caused by friction with the rotating shaft of the pump or the like, and deformation and abrasion of the resin material occur. In addition, in recent years, there are various pumps that operate under dry conditions, and there is a problem that the range of conditions of the rotation speed (V) and the sliding surface pressure (P) of the rotating shaft supported by the slide bearing and the range of PV values (rotation speed of the rotating shaft×sliding surface pressure) are expanded to higher values, and in such more severe conditions, the occurrence of deformation and abrasion of the resin material of the slide bearing becomes more remarkable.

Therefore, in addition to the above-described low wear rate during operation in the slurry, a resin material for a slide bearing of a slide bearing device is required to have a low friction coefficient during operation under dry conditions and to generate little heat, and to be able to suppress heat generation and operate even in a relatively high PV value range.

As a conventional slide bearing device, a slide bearing device including a slide bearing containing a fluororesin, an aromatic polyether ketone, carbon fibers, graphite, and unavoidable impurities, wherein the fluororesin has an area ratio of 2% to 10% and the carbon fibers have an area ratio of 4% to 17% and the graphite has an area ratio of 5% to 15%, and the aromatic polyether ketone and the unavoidable impurities occupy the remaining area in a sliding surface of the slide bearing is known (patent document 1). In the sliding bearing of the sliding bearing device described in patent document 1, the area ratio of graphite is 5% or more, the content ratio of graphite is high, and boron nitride is not contained as an additive.

Further, a sliding bearing device is known which comprises a sliding bearing containing an aromatic polyether ketone, talc, carbon fibers and unavoidable impurities, wherein the content of the talc with respect to the sliding bearing is 7 mass% or more and 18 mass% or less, and the area ratio of the carbon fibers on the sliding surface of the sliding bearing is 27% or more and 35% or less (patent document 2). In the sliding bearing of the sliding bearing device described in patent document 2, the area ratio of the carbon fiber has a value of 27% or more, and talc is contained as an additive.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2015-21551

Patent document 2: japanese patent laid-open publication No. 2019-100428

Disclosure of Invention

Problems to be solved by the invention

The purpose of the present invention is to provide a sliding bearing that has excellent slurry wear resistance when operated in water (slurry) containing foreign matter such as sand. Another object of the present invention is to provide a sliding bearing which has a small friction coefficient and generates little heat in a dry condition operation in which a sliding surface of the bearing is exposed to the atmosphere, and which can suppress heat generation and operate even in a relatively high PV value range, in addition to excellent slurry wear resistance in a slurry operation. Further, another object is to provide a slide bearing device provided with the slide bearing and a pump provided with the slide bearing device.

Means for solving the problems

In order to solve the above-described problems, according to one aspect of the present invention, there is provided a sliding bearing comprising a resin composition containing an aromatic polyether ketone, a fluororesin, boron nitride, carbon fibers, graphite and unavoidable impurities, wherein the content of graphite is 5 mass% or less (including 0 mass%) with respect to the resin composition, the total content of boron nitride, carbon fibers and graphite is 30 mass% or less, and the area ratio of carbon fibers in a sliding surface of the sliding bearing is less than 10%, wherein the area ratio of carbon fibers is: for 5 arbitrary parts of a sample piece cut out from the sliding surface of the sliding bearing, a portion having an observation field of view of 589 μm×442 μm in the vertical direction by an optical microscope (500 times) was subjected to image processing, and an average area ratio was obtained from the area of a region having a luminance of 75% or more in the HSB color space.

According to another aspect of the present invention, there is provided a sliding bearing comprising a sliding bearing formed of a resin composition containing an aromatic polyether ketone, a fluororesin, boron nitride, carbon fibers, graphite and unavoidable impurities, wherein the content of the graphite is 5 mass% or less (including 0 mass%) with respect to the resin composition, and the total content of the boron nitride, the carbon fibers and the graphite is 30 mass% or less, and the area ratio of the carbon fibers in a sliding surface of the sliding bearing is less than 10%, wherein the area ratio of the carbon fibers is: for 5 arbitrary parts of a sample piece cut out from the sliding surface of the sliding bearing, a portion having an observation field of view of 589 μm×442 μm in the vertical direction by an optical microscope (500 times) was subjected to image processing, and an average area ratio was obtained from the area of a region having a luminance of 75% or more in the HSB color space.

In any of the above aspects, it is preferable that the sliding surface of the sliding bearing is configured to be operable in both a state of being in contact with the atmosphere and a state of being in contact with water mixed with sand.

In any of the above embodiments, the aromatic polyether ketone is preferably polyether ketone, polyether ether ketone, polyether ketone, polyether ether ketone, or a combination thereof.

In any of the above embodiments, the fluororesin is preferably polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, or a combination thereof.

According to another aspect of the present invention, there is provided a pump including the sliding bearing.

Effects of the invention

According to the present invention, a slide bearing used in a slide bearing device for a radial bearing of a submersible pump, which has excellent slurry abrasion resistance when running in a slurry, can be provided. Further, it is possible to provide a sliding bearing which has excellent slurry abrasion resistance during operation in a slurry, has a small friction coefficient and generates little heat during operation under dry conditions, and can suppress heat generation and operate even in a relatively high PV value range. Further, a slide bearing device including the slide bearing and a pump including the slide bearing device can be provided.

Drawings

Fig. 1 is a cross-sectional view showing the whole of a vertical shaft pump that performs a preliminary standby operation.

Fig. 2 is an enlarged view of a bearing device suitable for the bearing shown in fig. 1.

Fig. 3 is a perspective view of a slide bearing provided in the bearing device shown in fig. 2.

FIG. 4 is a graph showing the relationship between the total (mass%) of boron nitride, carbon fiber and graphite and the wear rate (μm/h) in the slurry, in the sliding bearing devices of the examples and comparative examples of the present invention.

FIG. 5 is a graph showing the relationship between the PV value (MPa.m/s) and the temperature rise (. Degree. C.) of the sliding bearing device of example No.1 of the present invention.

FIG. 6 is a graph showing the relationship between the PV value (MPa.m/s) and the friction coefficient of the sliding bearing device of example No.1 of the present invention.

Detailed Description

Fig. 1 is a cross-sectional view showing the whole of a vertical shaft pump 3 that performs a preliminary standby operation. As shown in fig. 1, the vertical shaft pump 3 is provided with a discharge elbow 30 provided and fixed on the pump installation floor; a housing 29 connected to the lower end of the discharge elbow 30; a discharge tube 28 connected to a lower end of the housing 29 and accommodating the impeller 22 therein; and a suction bell 27 connected to a lower end of the discharge cylinder 28 and used for sucking water.

A single rotary shaft 10 formed by connecting upper and lower shafts to each other by a coupling 26 is disposed in the substantially central portions in the radial direction of a housing 29, a discharge tube 28, and a suction bell 27 of the vertical shaft pump 3. The rotary shaft 10 is supported by an upper bearing 32 fixed to the housing 29 via a support member and a lower bearing 33 fixed to the discharge tube 28 via a support member. An impeller 22 for sucking water into the pump is connected to one end side (suction bell 27 side) of the rotary shaft 10. The other end side of the rotary shaft 10 extends outside the vertical shaft pump 3 through a hole provided in the discharge elbow 30, and is connected to a driving machine such as an engine or a motor, not shown, for rotating the impeller 22. Between the rotary shaft 10 and the hole provided in the discharge elbow 30, a floating seal, gland seal or mechanical seal is provided, etc. seal 34, by means of which shaft seal 34 the outflow of water treated by the vertical shaft pump 3 to the outside of the vertical shaft pump 3 is prevented.

The drive machine is disposed on land so that maintenance checks can be easily performed. The rotation of the drive machine is transmitted to the rotary shaft 10, and the impeller 22 can be rotated. By the rotation of the impeller 22, water is sucked from the suction bell 27, and discharged from the discharge elbow 30 through the discharge cylinder 28 and the housing 29.

Fig. 2 is an enlarged view of a bearing device suitable for use in bearings 32, 33 shown in fig. 1. Fig. 3 is a perspective view of a slide bearing provided in the bearing device shown in fig. 2. As shown in fig. 2, the bearing device has a sleeve 11 formed of stainless steel, ceramic, sintered metal, or surface-modified metal on the outer circumference of the rotary shaft 10. The sleeve 11 may have a vickers hardness (Hv) of 800 or more and 2500 or less, for example. A hollow cylindrical slide bearing 1 made of a resin material is provided on the outer peripheral side of the sleeve 11. The outer peripheral surface of the sleeve 11 faces the inner peripheral surface (sliding surface) 1a of the sliding bearing 1 with a very narrow gap therebetween, and is configured to slide with respect to the sliding bearing 1. The slide bearing 1 is fixed to a support member 13 connected to a housing 29 (see fig. 1) or the like of the pump via a flange portion 12a by a bearing housing 12 formed of metal or resin. As shown in fig. 3, the slide bearing 1 has a hollow cylindrical shape, and an inner peripheral surface (sliding surface) 1a faces an outer peripheral surface of the sleeve 11, and an outer peripheral surface 1b is fitted in the bearing housing 12.

The slide bearing apparatus according to the present embodiment has, for example, the same structure as the slide bearing apparatus shown in fig. 2. That is, the slide bearing device of the present embodiment includes the rotary shaft 10 and the sleeve 11 as the rotary body, and the slide bearing 1 as the fixed body. The slide bearing 1 used in the slide bearing apparatus according to the present embodiment has the same structure as the slide bearing 1 shown in fig. 3.

The sliding bearing 1 of the present embodiment is formed of a resin composition containing an aromatic polyether ketone, a fluororesin, boron nitride, carbon fiber, graphite, and unavoidable impurities. The inner peripheral surface of the cylindrical sliding bearing 1 constitutes an inner peripheral surface (sliding surface) 1a of the bearing that contacts the outer peripheral surface of the sleeve 11.

In the resin composition for forming the sliding bearing of the present embodiment, the content of graphite is 5 mass% or less (including 0 mass%) with respect to the resin composition, the total content of boron nitride, carbon fibers and graphite is 30 mass% or less, and the area ratio of carbon fibers on the sliding surface of the sliding bearing is less than 10%.

In the sliding bearing formed by using the resin composition having the content of graphite, the total content of boron nitride, carbon fibers and graphite, and the area ratio of carbon fibers within the above numerical ranges, as shown in examples 1 and 2 described later, the wear rate in the slurry was 23 μm/h or less, and the PV value was: the temperature rise value of the sliding bearing under the condition of 1.5MPa m/s is below 120 ℃, and the PV value is as follows: the sliding bearing has a friction coefficient of 0.1 or less under the condition of 1.0MPa m/s, is excellent in slurry abrasion resistance during operation in slurry, has a small friction coefficient and generates little heat during operation under dry conditions, and can be operated while suppressing heat generation even in a relatively high PV value range.

The fluororesin has an effect of reducing the wear rate in the slurry and the friction coefficient at a PV value of less than 1.0mpa·m/s, but the temperature rise of the sliding bearing at a PV value of 1.0mpa·m/s or more tends to be large. Boron nitride has a lubricating effect at high temperatures. Graphite functions as a solid lubricant, but the lubricating effect tends to be low at high temperatures. The carbon fiber has the effects of increasing strength and reducing linear expansion coefficient. The present invention provides a sliding bearing which is excellent in slurry abrasion resistance during operation in a slurry, has a small friction coefficient and generates little heat during operation under dry conditions, and can be operated while suppressing heat generation even in a relatively high PV value range, by forming the sliding bearing from a resin composition in which the composition of a resin component (aromatic polyether ketone, fluororesin), boron nitride, carbon fiber, and graphite is optimized.

The total content of boron nitride, carbon fiber and graphite may be 30 mass% or less, 26 mass% or less, 23 mass% or 20 mass% or less, based on the resin composition. The total content of boron nitride, carbon fiber and graphite may be 5 mass% or more, 10 mass% or more, 15 mass% or more, 18 mass% or more or 20 mass% or more.

The content of graphite in the resin composition may be 5 mass% or less (including 0 mass%), or 3 mass% or more and 5 mass% or less.

The average particle diameter of the graphite is preferably more than 3 μm and 15 μm or less.

The area ratio of the carbon fiber on the sliding surface of the sliding bearing may be 9.5% or less, 9% or less, 8% or less, or 7% or less. The area ratio of the carbon fibers may be 1% or more, 2% or more, 3% or more, or 4% or more.

The content of the carbon fiber in the resin composition is not particularly limited, and may be 3 to 12 mass%, 4 to 11 mass%, or 5 to 10 mass%.

The carbon fibers are preferably composed of short fibers.

The diameter of the carbon fiber observed on the sliding surface 1a of the bearing is preferably 5 μm or more and 10 μm or less, more preferably 5.5 μm or more and 9 μm or less, and most preferably 6 μm or more and 8 μm or less. The diameter of the carbon fiber can be measured by image analysis using an optical microscope (digital microscope VHX-7000 (manufactured by Keyence Co., ltd.), objective lens VHX-E500 (500 to 2500 times)), and an image analysis program described later.

The length of the carbon fiber observed on the sliding surface 1a of the bearing is preferably 5 μm or more and 1000 μm or less, more preferably 6 μm or more and 500 μm or less, and most preferably 7 μm or more and 200 μm or less. The length of the carbon fiber can be measured by image analysis using an optical microscope (digital microscope VHX-7000 (manufactured by Keyence Co., ltd.), objective lens VHX-E500 (500 to 2500 times)), and an image analysis program described later.

The aspect ratio (length/diameter) of the carbon fiber observed on the sliding surface 1a of the bearing is preferably 2 to 100, more preferably 10 to 100, and most preferably 30 to 100.

The content of boron nitride in the resin composition is not particularly limited, and may be 13 to 22 mass%, 14 to 21 mass%, or 15 to 20 mass%.

The boron nitride is not particularly limited, and examples thereof include hexagonal boron nitride (h-BN), cubic boron nitride (c-BN) and combinations thereof, but hexagonal boron nitride is preferable.

The average particle diameter of the boron nitride is preferably greater than 4 μm and 20 μm or less.

The aromatic polyether ketone is not particularly limited, and polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone (PEKK), polyether ether ketone (PEEKK), and combinations thereof are exemplified, with polyether ether ketone being preferred.

The fluororesin is not particularly limited, and Polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), and combinations thereof may be mentioned, but polytetrafluoroethylene is preferable.

The content of the fluororesin to the resin composition is not particularly limited, and may be 10 mass% or more and less than 20 mass%, 12 mass% or more and 18 mass% or less, or 13 mass% or more and 17 mass% or less. In particular, by making the content of the fluororesin less than 20 mass%, the moldability in molding the sliding bearing from the resin composition can be improved.

(method for measuring the content of boron nitride)

The content of boron nitride can be measured by the following method.

Specifically, 100g of the molded sliding bearing was weighed, burned at 800 ℃, and components such as carbon fiber and fluororesin were decomposed and volatilized, and boron nitride was recovered as ash, and the mass of the ash was measured. Then, the ratio of the mass of ash (boron nitride) to the mass (100 g) of the sliding bearing was calculated as the content of boron nitride.

(method for measuring area ratio of carbon fiber)

The area ratio of the carbon fiber is an average area ratio obtained by performing image processing on a portion having an observation field of view of 589 μm×442 μm in a vertical direction by an optical microscope (500 times) for 5 arbitrary portions of a sample piece cut out from a sliding surface of a sliding bearing, and from an area of a region having a luminance (Brightness) of 75% or more in an HSB color space. Specific examples of such a method for measuring the area ratio of the carbon fiber will be described below.

Square test pieces of 5mm in longitudinal direction by 5mm in transverse direction were cut out from the sliding surface of the molded slide bearing, and the surfaces of the test pieces were polished. On the polished surface of the sample piece, 5 sites were randomly selected, and each site was imaged on a plane having a vertical axis of 589 μm×442 μm using an optical microscope (digital microscope VHX-7000 (manufactured by Keyence corporation), objective lens VHX-E500 (500 to 2500 magnification)). As conditions at the time of planar photographing, magnification is adopted: 500 times, epi-illumination: coaxial reflection, pixel: 2880×2160. The identification of the portion of the carbon fiber was performed by image analysis using a plane of 589 μm×442 μm in the longitudinal direction as an observation portion. The ratio of the area of the carbon fiber to the entire area of the observation portion was calculated, and the average of the calculated values of 5 portions was obtained as the area ratio of the carbon fiber. Here, the image analysis of the observation portion of the slide bearing surface can use an image analysis program: image J (according to instruction "Analyze particles"), the Image analysis conditions were set to pixels "Hue" 0 to 225, saturation "0 to 225, brightness" 170 to 225 "and the other to default in the measurement program Color Threshold. Using this image analysis program, this is performed by extracting a portion having the same pixel characteristics as those of the carbon fiber (brightness, color). In the Image analysis program (Image J), the areas with the luminances 170 to 225 are extracted, which means that the areas with the luminances of 75% or more are extracted in the HSB color space.

The area ratio of the carbon fiber may be directly measured by the above method for each sliding bearing, but may be different from the above method, for example, the area ratio of the carbon fiber may be calculated based on the volume ratio (vol%) of the carbon fiber as described below.

Regarding the relationship between the volume rate (vol%) and the area rate, such as transition and hope of morphology evaluation of material structure of zornia straight and the like, iron and steel, vol.100 (2014), no.10, p.1182-1190; it is known that, in a multiphase tissue, a relational expression that the average area ratio and the volume ratio are equal to each other between the average area ratio and the volume ratio obtained from a plurality of observation surfaces is established as described in "computer-aided 3D metrology morphology", vo.61 (2011), no.2, and p.78-84. Therefore, the value of the volume ratio (volume%) of the carbon fibers in the sliding bearing can be used as the value of the area ratio of the carbon fibers. The volume ratio (vol%) of the carbon fiber in the sliding bearing may be calculated based on the content (vol%) and specific gravity of each component contained in the sliding bearing, for example, as shown in examples described later.

In the present invention, a sliding bearing can be produced by dry-blending a powder of an aromatic polyether ketone, a powder of a fluororesin, a powder of boron nitride, a powder of a carbon fiber and a powder of graphite to prepare a resin composition, compression molding the resin composition, and then subjecting the resin composition to surface processing. Further, the slide bearing device can be manufactured using the slide bearing, and further, the pump can be manufactured using the slide bearing device.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples.

Examples

Example 1

In example 1, powders of aromatic polyether ketone (polyether ether ketone), fluororesin (polytetrafluoroethylene), boron nitride (average particle diameter 4 μm), carbon fiber (diameter about 6 μm and length about 100 μm), and graphite (particle diameter 1 to 20 μm) (graphite is not blended in examples 1 to 3 of the present invention) were dry-blended so that the content (mass%) of each component became the values shown in table 1, and pellets were produced. The obtained pellets were placed in a mold, pressurized and heated, molded 1 time, and then machined 2 times to give a detailed shape, thereby producing a sliding bearing. Then, the obtained sliding bearing was evaluated for the wear rate in the slurry, which will be described later. The results are shown in Table 1 and FIG. 4.

TABLE 1

The volume percentage (vol%) of the carbon fibers of the sliding bearings of examples 1 to 4 and comparative examples 1 to 6 of the present invention was calculated based on the content (mass%) of each component and the specific gravity (aromatic polyether ketone: 1.3, fluororesin: 2.17, boron nitride: 2.3, carbon fiber: 1.8, graphite: 1.8) shown in Table 1. The results are shown in Table 1. As described above, in the multiphase structure, the relationship in which the average area ratio (%) is equal to the volume ratio (vol%) is established, and therefore the volume ratio (vol%) of the carbon fibers shown in table 1 is equal to the average area ratio (%) of the carbon fibers.

The wear rates of the sliding bearings of examples 1 to 4 and comparative examples 1 to 6 in the slurry were measured as follows.

(wear Rate in slurry)

First, silica sand (main component: siO 2) having an average particle diameter of about 5 μm and silica sand having an average particle diameter of about 30 μm were treated with 1:1 was put into water so as to have a concentration of 3000mg/L, and a slurry was prepared. The bearing device including the slide bearing (the device including the rotary shaft 10, the sleeve 11, the slide bearing 1, and the bearing housing 12 (including the flange portion 12 a) of fig. 2) was immersed in the slurry obtained, and the initial surface roughness (Ra) of the slide bearing with respect to the WC-based cemented carbide was set to 3.2 in a flat sliding state at a PV value of 0.6mpa·m/s in the slurry maintained at 25 ℃ for 8 hours, and the wear rate (μm/h) of the slide bearing was calculated.

As is clear from the results shown in table 1 and fig. 4, the sliding bearings of examples 1 to 4 of the present invention, in which the content of graphite was 5 mass% or less (including 0 mass%), the total content of boron nitride, carbon fiber and graphite was 30 mass% or less, and the volume ratio (volume%) of carbon fiber was less than 10% (i.e., the area ratio was less than 10%), had a low wear rate in the slurry of 23 μm/h or less.

On the other hand, the sliding bearings of comparative examples No.1-6, in which the total content of boron nitride, carbon fibers and graphite exceeds 30 mass% and the volume ratio (volume%) of carbon fibers is 10% or more (i.e., the area ratio is 10% or more), had a wear rate in the slurry of 28 μm/h or more, although the content of graphite was 5 mass% or less.

As is clear from the above, as in the present invention examples nos. 1 to 4, the composition of the resin composition forming the sliding bearing was set to a specific composition, so that the wear rate in the slurry was reduced, and the slurry wear resistance was improved.

Example 2

The following evaluation of critical PV value and friction coefficient was performed for the sliding bearing of inventive example No.1 shown in table 1. The results are shown in table 2 and fig. 5 and 6.

(critical PV value)

In a dry test using a bearing device including the same plain bearing as described above (wear rate in slurry), at the PV value: the slide bearing was operated for 2 hours under conditions of 0.30, 0.35, 0.40, 0.60 or 0.70 MPa.m/s, and the temperature rise value was measured at a position 5mm deep from the sliding surface of the slide bearing at each PV value. Further, a graph (horizontal axis: PV value, vertical axis: temperature rise value) shown in fig. 5 was prepared, and an approximate straight line was drawn to obtain a PV value: an estimated value of the temperature rise at 1.5 MPa.m/s.

(coefficient of friction)

Using a bearing device including a plain bearing similar to the above (wear rate in slurry), the PV value was: the sliding was performed at 0.30, 0.35, 0.40, 0.60 or 0.70 MPa.m/s against a surface having an initial surface roughness (Ra) of 3.2 of the WC-based cemented carbide for 2 hours, and the coefficient of friction was continuously measured at 0.5 second intervals over a period of 2 hours. The average value of the friction coefficient of the second half of the 2-hour operation for 1 hour was calculated as the friction coefficient of the sliding bearing for each PV value. In the graph shown in fig. 6 (horizontal axis: PV value, vertical axis: friction coefficient), the PV value is obtained by drawing an approximate straight line: an estimated value of the friction coefficient under the condition of 1.0 MPa.m/s.

TABLE 2

As can be seen from the approximate straight line of fig. 5, the PV value of the sliding bearing of example No.1 of the present invention can be estimated: the temperature rise value of the sliding bearing under the condition of 1.5MPa m/s is below 120 ℃, and the temperature rise of the sliding bearing can be restrained.

Further, as can be seen from the approximate straight line of fig. 6, the PV value of the sliding bearing of example No.1 of the present invention can be estimated: the friction coefficient of the sliding bearing under the condition of 1.0MPa m/s is below 0.1, so that friction can be reduced.

Therefore, it was found that the sliding bearing of example No.1 of the present invention was excellent in slurry abrasion resistance, and the evaluation of the critical PV value was good, and the friction was small and good.

As described above, in the case of the pump including the slide bearing according to the embodiment of the present invention as the radial bearing, in the water drain plant that handles water mixed with foreign matter, even if the operation in water and the operation in the atmosphere are repeated, the abrasion of the slide bearing can be suppressed, and the low friction (lubricity) of the slide bearing can be maintained.

Description of the reference numerals

1 … sliding bearing

1a … inner peripheral surface (sliding surface)

3 … vertical shaft pump

10 … rotating shaft

11 … sleeve

Claims

1. A sliding bearing formed of a resin composition containing an aromatic polyether ketone, a fluororesin, boron nitride, carbon fibers, graphite and unavoidable impurities,

the content of graphite is 5 mass% or less (including 0 mass%) and the total content of boron nitride, carbon fiber and graphite is 30 mass% or less,

the area ratio of the carbon fiber in the sliding surface of the sliding bearing is less than 10%, wherein the area ratio of the carbon fiber is: for 5 arbitrary parts of a sample piece cut out from the sliding surface of the sliding bearing, a portion having an observation field of view of 589 μm×442 μm in the vertical direction by an optical microscope (500 times) was subjected to image processing, and an average area ratio was obtained from the area of a region having a luminance of 75% or more in the HSB color space.

2. A slide bearing device is provided with a slide bearing,

the sliding bearing is formed by a resin composition containing aromatic polyether ketone, fluororesin, boron nitride, carbon fiber, graphite and unavoidable impurities,

3. The slide bearing apparatus according to claim 2, wherein the slide surface of the slide bearing is configured to be operable in both a state of contact with the atmosphere and a state of contact with water mixed with sand.

4. A plain bearing arrangement according to claim 2 or 3, wherein the aromatic polyether ketone is a polyether ketone, a polyether ether ketone, a polyether ketone, a polyether ether ketone, or a combination thereof.

5. The sliding bearing device according to any one of claims 2 to 4, wherein the fluororesin is polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, or a combination thereof.

6. A pump comprising the slide bearing device according to any one of claims 2 to 5.