JP2021060122A - Slide bearing, slide bearing device and pump - Google Patents

Abstract

To provide a slide bearing excellent in slurry abrasion resistance during operation in water (slurry) containing foreign matter such as earth and sand, and a pump comprising the slide bearing.SOLUTION: Provided are a slide bearing and a slide bearing device, wherein a slide bearing 1 is formed from a resin composition consisting of aromatic polyetherketone, fluororesin, boron nitride, carbon fiber, graphite and unavoidable impurities, wherein the content of the graphite with respect to the resin composition is 5% by mass or less (including 0% by mass), the total content of the boron nitride, the carbon fiber and the graphite is 30% by mass or less, and the area ratio of the carbon fibers on a slide surface of the slide bearing is less than 10%.SELECTED DRAWING: Figure 3

Description

The present invention relates to a slide bearing preferably used as a radial bearing of a rotating machine such as a pump, a slide bearing device provided with the slide bearing, and a pump provided with the slide bearing device.

When using a plain bearing device equipped with a plain bearing made of a resin material for a pump, etc., it is assumed that foreign matter such as earth and sand is mixed in the water handled by the pump, etc., and the hardness that is the main component of the foreign matter It is necessary to consider the phenomenon that the large SiO ₂ invades the sliding surface of the bearing and wears the resin material. That is, when operating a pump or the like in water containing foreign matter, it is necessary to consider the problem that the amount of wear of the resin slide bearing increases and the bearing life is shortened.

Therefore, the resin material used for the slide bearing of the slide bearing device is required to have a low wear rate during operation in a slurry such as _{SiO 2.}

On the other hand, in vertical pumps and the like, in a plain bearing device, not only the slide surface of the bearing is operated in water, but also when it is operated in the atmosphere such as a controlled operation or a preceding standby operation, that is, a slide. The bearing slide surface of the bearing device may be operated in dry conditions where it is exposed to the atmosphere. When the slide bearing device is operated under dry conditions, there is a problem that the temperature of the resin material on the slide surface of the bearing rises due to heat generated by friction with the rotating shaft of a pump or the like, causing deformation and wear of the resin material. .. In recent years, there are various types of pumps that are operated under dry conditions, and the range of conditions for the rotational speed (V) and sliding surface pressure (P) of the rotating shaft supported by the slide bearing, and the PV value (of the rotating shaft). The range of (rotational speed x sliding surface pressure) is expanding to higher value conditions, and under such more severe conditions, the above-mentioned deformation and wear of the resin material of the slide bearing become more remarkable. There is a problem.

Therefore, in addition to the low wear rate during operation in the slurry described above, the resin material used for the slide bearing of the slide bearing device has a small coefficient of friction and low heat generation during operation under dry conditions, and is compared. It is also required that the operation can be performed while suppressing heat generation even in the range of a target high PV value.

The conventional plain bearing device is a plain bearing device including a plain bearing containing fluorine resin, aromatic polyetherketone, carbon fiber, graphite, and unavoidable impurities, and the plain contact surface of the plain bearing is made of the fluororesin. Has an area ratio of 2% or more and 10% or less, the carbon fiber has an area ratio of 4% or more and 17% or less, the graphite has an area ratio of 5% or more and 15% or less, and the aromatic. A plain bearing device (Patent Document 1) is known in which polyetherketone and the unavoidable impurities occupy the remaining area. The slide bearing in the slide bearing device described in Patent Document 1 has a graphite area ratio of 5% or more, a high graphite content, and does not contain boron nitride as an additive.
Further, it is a slide bearing device including a slide bearing containing aromatic polyetherketone, talc, carbon fiber, and unavoidable impurities, and the content of the talc in the slide bearing is 7% by mass or more and 18% by mass or less. A plain bearing device (Patent Document 2) is known in which the area ratio of the carbon fiber on the slide surface of the slide bearing is 27% or more and 35% or less. The plain bearing in the plain bearing device described in Patent Document 2 has a high carbon fiber area ratio of 27% or more, and contains talc as an additive.

Japanese Unexamined Patent Publication No. 2015-21551 Japanese Unexamined Patent Publication No. 2019-100428

An object of the present invention is to provide a slide bearing having excellent slurry wear resistance during operation in water (slurry) containing foreign matter such as earth and sand. Further, the present invention has excellent slurry wear resistance performance during operation in a slurry, and also has a small friction coefficient, low heat generation, and low heat generation in operation under dry conditions where the sliding surface of the bearing is exposed to the atmosphere. Another object of the present invention is to provide a slide bearing capable of suppressing heat generation and operating even in a relatively high PV value range. Another object of the present invention is to provide a slide bearing device provided with the slide bearing and a pump provided with the slide bearing device.

In order to solve the above-mentioned problems, according to one embodiment of the present invention,
It is a plain bearing
The plain bearing is formed of a resin composition composed of aromatic polyetherketone, fluororesin, boron nitride, carbon fiber, graphite, and unavoidable impurities.
The content of the graphite with respect to the resin composition is 5% by mass or less (including 0% by mass), and the total content of the boron nitride, the carbon fibers, and the graphite is 30% by mass or less. ,
The area ratio of the carbon fibers on the sliding surface of the slide bearing is less than 10%, however, the area ratio of the carbon fibers is such that the area ratio of the carbon fibers is an optical microscope (for any five points of the sample piece cut out from the sliding surface of the slide bearing). Observation field by 500 times): An average area ratio obtained from the area of a region having a Brightness of 75% or more in the HSB color space by image processing a portion of 589 μm in length × 442 μm in width.
The plain bearings are provided.

According to another embodiment of the invention
A plain bearing device equipped with a plain bearing.
The plain bearing is formed of a resin composition composed of aromatic polyetherketone, fluororesin, boron nitride, carbon fiber, graphite, and unavoidable impurities.
The content of the graphite with respect to the resin composition is 5% by mass or less (including 0% by mass), and the total content of the boron nitride, the carbon fibers, and the graphite is 30% by mass or less. ,
The area ratio of the carbon fibers on the sliding surface of the slide bearing is less than 10%, however, the area ratio of the carbon fibers is such that the area ratio of the carbon fibers is an optical microscope (for any five points of the sample piece cut out from the sliding surface of the slide bearing). Observation field by 500 times): An average area ratio obtained from the area of a region having a Brightness of 75% or more in the HSB color space by image processing a portion of 589 μm in length × 442 μm in width.
The plain bearing device is provided.

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

In any of the above forms, the aromatic polyetherketone is preferably a polyetherketone, a polyetheretherketone, a polyetherketoneketone, a polyetheretherketoneketone, or a combination thereof.

In any of the above forms, the fluororesin is a polytetrafluoroethylene, a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, a tetrafluoroethylene / hexafluoropropylene copolymer, or a tetrafluoroethylene / ethylene. It is preferably a polymer or a combination thereof.

According to another embodiment of the present invention, a pump provided with the above-mentioned plain bearing is provided.

According to the present invention, it is possible to provide a plain bearing device used in a plain bearing device for a radial bearing of a submersible pump, which has excellent slurry wear resistance during operation in a slurry. In addition to being excellent in slurry wear resistance during operation in a slurry, heat generation is suppressed even in a relatively high PV value range with a small coefficient of friction and low heat generation during operation under dry conditions. It is also possible to provide a slide bearing that is operable. Further, it is also possible to provide a slide bearing device provided with the slide bearing and a pump provided with the slide bearing device.

It is sectional drawing which shows the whole of the vertical shaft pump which performs the advance standby operation. It is an enlarged view of the bearing apparatus applied to the bearing shown in FIG. It is a perspective view of the slide bearing installed in the bearing device shown in FIG. It is a graph which shows the relationship between the total (mass%) of boron nitride, carbon fiber, and graphite and the wear rate (μm / h) in a slurry for the slide bearing apparatus of this invention example and comparative example. Example No. of the present invention. It is a graph which shows the relationship between the PV value (MPa · m / s) and the temperature rise value (° C.) about the slide bearing apparatus of 1. Example No. of the present invention. It is a graph which shows the relationship between the PV value (MPa · m / s) and the friction coefficient about the slide bearing apparatus of 1.

FIG. 1 is a cross-sectional view showing the entire vertical shaft pump 3 that performs the preceding standby operation. As shown in FIG. 1, the vertical shaft pump 3 has a discharge elbow 30 installed and fixed on the floor where the pump is installed, a casing 29 connected to the lower end of the discharge elbow 30, and an impeller 22 connected to the lower end of the casing 29. It is provided with a discharge bowl 28 for storing the water inside, and a suction bell 27 connected to the lower end of the discharge bowl 28 and for sucking water.

At the substantially central portion in the radial direction of the casing 29, the discharge bowl 28, and the suction bell 27 of the vertical shaft pump 3, one rotating shaft 10 formed by connecting two upper and lower shafts to each other by a shaft joint 26 is formed. Have been placed. The rotating shaft 10 is supported by an upper bearing 32 fixed to the casing 29 via a support member and a lower bearing 33 fixed to the discharge bowl 28 via the support member. An impeller 22 for sucking water into the pump is connected to one end side (suction bell 27 side) of the rotating shaft 10. The other end side of the rotating shaft 10 extends to the outside of the vertical shaft pump 3 through a hole provided in the discharge elbow 30, and is connected to a drive machine such as an engine or a motor that rotates the impeller 22. A shaft seal 34 such as a floating seal, a gland packing, or a mechanical seal is provided between the rotating shaft 10 and the hole provided in the discharge elbow 30, and the water handled by the vertical shaft pump 3 is collected by the shaft seal 34. Prevent the outflow to the outside of 3.

The drive unit is installed on land so that maintenance and inspection can be easily performed. The rotation of the drive machine is transmitted to the rotation shaft 10, and the impeller 22 can be rotated. Water is sucked from the suction bell 27 by the rotation of the impeller 22, passes through the discharge bowl 28 and the casing 29, and is discharged from the discharge elbow 30.

FIG. 2 is an enlarged view of a bearing device applied to the bearings 32 and 33 shown in FIG. FIG. 3 is a perspective view of a plain bearing installed in the bearing device shown in FIG. As shown in FIG. 2, the bearing device has a sleeve 11 made of stainless steel, ceramics, sintered metal, or surface-modified metal on the outer periphery of the rotating shaft 10. The sleeve 11 can have a Vickers hardness (Hv) of 800 or more and 2500 or less, for example. A slide bearing 1 made of a hollow cylindrical 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 (slip surface) 1a of the slide bearing 1 via a very narrow clearance, and is configured to slide with respect to the slide bearing 1. The slide bearing 1 is fixed to a support member 13 connected to a pump casing 29 (see FIG. 1) or the like via a brim portion 12a by a bearing case 12 made of metal or resin. As shown in FIG. 3, the slide bearing 1 has a hollow cylindrical shape, the inner peripheral surface (slip surface) 1a faces the outer peripheral surface of the sleeve 11, and the outer peripheral surface 1b fits into the bearing case 12. Will be done.

The slide bearing device according to the present embodiment has, for example, the same structure as the slide bearing device shown in FIG. That is, the slide bearing device according to the present embodiment has a rotating shaft 10 and a sleeve 11 which are rotating bodies, and a sliding bearing 1 which is a fixed body. Further, the slide bearing 1 used in the slide bearing device according to the present embodiment has the same structure as the slide bearing 1 shown in FIG.

The plain bearing 1 according to the present embodiment is formed of a resin composition composed of aromatic polyetherketone, fluororesin, boron nitride, carbon fiber, graphite, and unavoidable impurities. The inner peripheral surface of the cylindrical slide bearing 1 constitutes the inner peripheral surface (slip surface) 1a of the bearing that comes into contact with the outer peripheral surface of the sleeve 11.

In the resin composition for forming the slide bearing according to the present embodiment, the graphite content with respect to the resin composition is 5% by mass or less (including 0% by mass), and the boron nitride, the carbon fiber, and the like. The total content of the graphite is 30% by mass or less, and the area ratio of the carbon fibers on the sliding surface of the slide bearing is less than 10%.
The plain bearings formed by using a resin composition in which the content of graphite, the total content of boron nitride, carbon fibers, and graphite and the area ratio of carbon fibers are within the above numerical ranges are described in Example 1 and the following. As shown in 2, the wear rate in the slurry is 23 μm / h or less, the temperature rise value of the slide bearing at the PV value: 1.5 MPa · m / s is 120 ° C. or less, and the PV value: 1.0 MPa · m / s. The friction coefficient of the slide bearing in s is 0.1 or less, the slurry wear resistance performance during operation in a slurry is excellent, and the friction coefficient is small and heat generation is small in operation under dry conditions, and the PV value is relatively high. Even within the range, heat generation can be suppressed and operation becomes possible.

Fluororesin has the effect of reducing the wear rate in the slurry and the friction coefficient at a PV value of less than 1.0 MPa · m / s, but at a PV value of 1.0 MPa · m / s or more. The temperature rise of the slide bearing tends to be large. Boron nitride has a lubricating effect at high temperatures. Graphite functions as a solid lubricant, but tends to have a reduced lubricating effect at high temperatures. Carbon fibers have the effect of increasing strength and reducing the coefficient of linear expansion. The present invention forms a plain bearing from a resin composition with an optimized composition of resin components (aromatic polyetherketone, fluororesin), boron nitride, carbon fibers, and graphite during operation in a slurry. It is possible to provide a plain bearing which is excellent in slurry wear resistance, has a small friction coefficient and generates little heat in operation under dry conditions, and can suppress heat generation even in a relatively high PV value range.

The total content of boron nitride, carbon fiber, and graphite with respect to the resin composition shall be 30% by mass or less, 28% by mass or less, 26% by mass or less, 23% by mass or less, or 20% by mass or less. You can also. The total content of boron nitride, carbon fiber, and graphite can be 5% or more, 10% or more, 15% or more, 18% by mass or more, or 20% or more.

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

The average particle size of graphite is preferably larger than 3 μm and 15 μm or less.

The area ratio of carbon fibers on the sliding surface of the slide bearing is less than 10%, and may be 9.5% or less, 9% or less, 8% or less, or 7% or less. Further, 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 carbon fibers in the resin composition is not particularly limited, but may be 3% by mass or more and 12% by mass or less, 4% by mass or more and 11% by mass or less, or 5% by mass or more and 10% by mass or less.

The carbon fibers are preferably composed of short fibers.
The diameter of the carbon fibers 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 is image-analyzed using the above-mentioned image analysis program using an optical microscope (digital microscope VHX-7000 (manufactured by Keyence), objective lens VHX-E500 (500 to 2500 times)). It can be measured from the above.
The length of the carbon fibers 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 analyzed using an optical microscope (digital microscope VHX-7000 (manufactured by Keyence), objective lens VHX-E500 (500 to 2500 times)) using the above-mentioned image analysis program. It can be measured by doing.
The aspect ratio (length / diameter) of the carbon fibers observed on the sliding surface 1a of the bearing is preferably 2 or more and 100 or less, more preferably 10 or more and 100 or less, and most preferably 30 or more and 100 or less.

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

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 size of boron nitride is preferably larger than 4 μm and 20 μm or less.

The aromatic polyetherketone is not particularly limited, and includes polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetheretherketoneketone (PEEKK), and combinations thereof. Although mentioned, polyetheretherketone is preferable.

The fluororesin is not particularly limited, and is polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetra. Fluoroethylene-ethylene copolymer (ETFE) and combinations thereof can be mentioned, but polytetrafluoroethylene is preferable.
The content of the fluororesin in the resin composition is not particularly limited, but may be 10% by mass or more and less than 20% by mass, 12% by mass or more and 18% by mass or less, or 13% by mass or more and 17% by mass or less. In particular, by setting the content of the fluororesin to less than 20% by mass, the moldability when molding the slide bearing from the resin composition can be improved.

(Measuring method of boron nitride content)
The content of boron nitride can be measured by the following method.
That is, 100 g of the molded slide bearing is weighed and fired at 800 ° C. to decompose and volatilize components such as carbon fiber and fluororesin, boron nitride is recovered as ash, and the mass of ash is measured. Then, the ratio of the mass of the ash (boron nitride) to the mass (100 g) of the slide bearing is calculated and used as the boron nitride content.

(Measuring method of carbon fiber area ratio)
The area ratio of carbon fibers is determined in the HSB color space by image processing the observation field of view with an optical microscope (500 times): 589 μm in length × 442 μm in width for any 5 points of the sample piece cut out from the slide surface of the slide bearing. It is an average area ratio obtained from the area of an area where Brightness is 75% or more. A specific example of such a method for measuring the area ratio of carbon fibers will be described below.
A square sample piece of 5 mm in length × 5 mm in width is cut out from the sliding surface of the molded slide bearing, and the surface of the sample piece is polished. Five points were randomly selected on the polished surface of the sample piece, and each part was used with an optical microscope (digital microscope VHX-7000 (manufactured by Keyence), objective lens VHX-E500 (500 to 2500 times)). An image is taken on a plane of 589 μm in length × 442 μm in width. As conditions for shooting a flat surface, a magnification of 500 times, epi-illumination: coaxial epi-illumination, and pixels: 2880 × 2160 are adopted. The photographed plane of 589 μm in length × 442 μm in width is used as the observation portion, and the carbon fiber portion is identified by image analysis. The ratio of the carbon fiber area to the total area of the observation portion is calculated, and the average of the calculated values at the five locations is calculated and used as the carbon fiber area ratio. Here, the image analysis of the observed portion of the surface of the sliding bearing can be performed by using the image analysis program: Image J (implemented by the "Analyze parameters" command), and the image analysis condition is set to the pixel "Color Threshold" in the measurement program Color Threshold. Set to "Hue 0-225, Saturation 0-225, Brightness 170-225", and set the others to the default settings. This image analysis program is used to extract a portion having the same pixel characteristics as the pixel characteristics (brightness, color) of the carbon fiber. Brightness in the above image analysis program (Image J)
The region of 170 to 225 is extracted, which means that the region of Brightness of 75% or more is extracted in the HSB color space.

For each plain bearing, the area ratio of carbon fibers can be directly measured by the above method, but unlike that, for example, the carbon fibers are based on the volume ratio (volume%) of the carbon fibers as shown below. It is also possible to calculate the area ratio of.
Regarding the relationship between volume fraction (volume%) and area fraction, Naoko Sato et al., “Transition and Prospects of Morphological Evaluation of Material Structure”, Iron and Steel, Vol.100 (2014), No.10, p.1182-1190 And, as described in Yoshitaka Adachi, “Computer Assisted 3D Metric Morphology”, Vo. 61 (2011), No. 2, p.78-84, it is obtained from multiple observational surfaces in a multiphase structure. It is known that the relational expression that the average area fraction and the volume fraction are equal is established between the average area ratio and the volume fraction. Therefore, the value of the volume fraction (volume%) of the carbon fibers in the slide bearing can be used as the value of the area fraction of the carbon fibers. Here, the volume fraction (volume%) of the carbon fibers in the slide bearing is calculated based on, for example, the content ratio (mass%) and the specific gravity of each component contained in the slide bearing, as shown in Examples described later. You can also.

In the present invention, a resin composition was prepared by dry blending a powder of aromatic polyetherketone, a powder of fluororesin, a powder of boron nitride, a carbon fiber, and a powder of graphite, and the resin composition was compression-molded. After that, a slide bearing can be manufactured by subjecting it to surface processing. In addition, the plain bearing device can be used to manufacture a plain bearing device, and further, the plain bearing device can be used to manufacture a pump.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the contents described in the Examples.

(Example 1)
In Example 1, a powder of aromatic polyetherketone (polyetheretherketone), a powder of fluororesin (polytetrafluoroethylene), so that the content (% by mass) of each component becomes the value shown in Table 1. Powder of boron nitride (average particle size 4 μm), carbon fiber (diameter about 6 μm, length about 100 μm), and graphite (particle size 1 to 20 μm) powder (No. 1 to 3 of the present invention does not contain graphite). ) Was dry-blended to produce pellets. The obtained pellets were placed in a mold, pressed and heated to form a primary process, and then a detailed shape was given by machining a secondary process to manufacture a plain bearing. Then, the obtained slide bearing was evaluated for the wear rate in the slurry described later. The results are shown in Table 1 and FIG.

The content (mass%) of each component shown in Table 1 and the specific gravity of each component (aromatic graphite ketone: 1.3, fluororesin: 2.17, boron nitride: 2.3, carbon fiber: 1). Based on 0.8, graphite: 1.8), Example No. 1 of the present invention. 1-4 and Comparative Example No. The volume fraction (volume%) of the carbon fibers of the slide bearings 1 to 6 was calculated. The results are shown in Table 1. As described above, in the multiphase structure, the relationship that the average area fraction (%) is equal to the volume fraction (volume%) is established. Therefore, the volume fraction (volume%) of the carbon fibers shown in Table 1 is that of the carbon fibers. It will be equal to the average area fraction (%).

Example No. of the present invention. 1-4 and Comparative Example No. The wear rates of the slide bearings 1 to 6 in the slurry were measured according to the following procedure.
(Abrasion rate in slurry)
First, the average particle diameter of about 5μm of quartz sand (principal component: Si0 ₂₎ and the average particle size of about 30μm silica sand 1: a concentration of 3000 mg / L to Including sand particles at a ratio of 1 As described above, the mixture was poured into water to prepare a slurry. A bearing device including a slide bearing (a device including a rotating shaft 10, a sleeve 11, a slide bearing 1, and a bearing case 12 (including a brim portion 12a) in FIG. 2) is submerged in the obtained slurry for 8 hours. In a slurry maintained at 25 ° C., under the condition of PV value of 0.6 MPa · m / s, the initial surface roughness (Ra) of the WC-based superhard alloy slides with respect to a plane of 3.2 and slides. The bearing wear rate (μm / h) was calculated.

From the results of Table 1 and FIG. 4, the graphite content is 5% by mass or less (including 0% by mass), the total content of boron nitride, carbon fiber, and graphite is 30% by mass or less, and carbon. Example No. of the present invention in which the volume ratio (volume%) of the fibers is less than 10% (that is, the area ratio is less than 10%). The slide bearings 1 to 4 had a low wear rate of 23 μm / h or less in the slurry.
On the other hand, although the graphite content is 5% by mass or less, the total content of boron nitride, carbon fibers, and graphite exceeds 30% by mass, and the volume ratio (volume%) of the carbon fibers is 10% or more. (That is, the area ratio is 10% or more). The slide bearings 1 to 6 had a high wear rate of 28 μm / h or more in the slurry.
From the above, the present invention example No. It was found that by making the composition of the resin composition forming the slide bearing specific as in 1 to 4, the wear rate in the slurry can be reduced and the slurry wear resistance can be improved.

(Example 2)
Example No. of the present invention shown in Table 1. The following limit PV value and friction coefficient were evaluated for the slide bearing No. 1. The results are shown in Table 2 and FIGS. 5 and 6.

(Limited PV value)
In a dry test using a bearing device including a plain bearing similar to the above (wear rate in slurry), PV values: 0.30, 0.35, 0.40, 0.60, or 0.70 MPa · m The operation was performed at / s for 2 hours, and the temperature rise value at a depth of 5 mm from the slide surface of the slide bearing was measured at each PV value. Then, the graph shown in FIG. 5 (horizontal axis: PV value, vertical axis: temperature rise value) is created, and the estimated value of the temperature rise value at PV value: 1.5 MPa · m / s is calculated by drawing an approximate straight line. did.

(Coefficient of friction)
Using a bearing device including a plain bearing similar to the above (wear rate in slurry), PV values: 0.30, 0.35, 0.40, 0.60, or 0.70 MPa · m / s. For 2 hours, slide the WC-based superhard alloy against a surface having an initial surface roughness (Ra) of 3.2 without using lubricating oil, and rub continuously at 0.5 second intervals for 2 hours. The coefficient was measured. The average value of the friction coefficient in the latter 1 hour of the operation for 2 hours was calculated and used as the friction coefficient of the slide bearing at each PV value. Then, a graph (horizontal axis: PV value, vertical axis: friction coefficient) shown in FIG. 6 was created, and an estimated value of the friction coefficient at a PV value of 1.0 MPa · m / s was calculated by drawing an approximate straight line.

From the approximate straight line of FIG. 5, the present invention example No. As for the slide bearing of No. 1, it can be estimated that the temperature rise value of the slide bearing at a PV value of 1.5 MPa · m / s is 120 ° C. or less, and it can be seen that the temperature rise of the slide bearing can be suppressed.
Further, from the approximate straight line of FIG. 6, the present invention example No. It can be estimated that the sliding bearing of No. 1 has a friction coefficient of 0.1 or less at a PV value of 1.0 MPa · m / s, and it can be seen that the friction can be reduced.
Therefore, the present invention example No. It was found that the slide bearing No. 1 was excellent in slurry wear resistance, had a good evaluation of the limit PV value, and had a small friction.

As described above, in the case of a pump provided with the slide bearing of the slide bearing device according to the embodiment of the present invention as a radial bearing, underwater operation and atmospheric operation are repeated in a drainage pump station for treating foreign matter mixed water. Even so, it is possible to suppress wear of the slide bearing and maintain low friction (lubricity) of the slide bearing.

1 ... Plain bearing 1a ... Inner peripheral surface (slip surface)
3 ... Vertical shaft pump 10 ... Rotating shaft 11 ... Sleeve

Claims (6)

It is a plain bearing
The plain bearing is formed of a resin composition composed of aromatic polyetherketone, fluororesin, boron nitride, carbon fiber, graphite, and unavoidable impurities.
The content of the graphite with respect to the resin composition is 5% by mass or less (including 0% by mass), and the total content of the boron nitride, the carbon fibers, and the graphite is 30% by mass or less. ,
The area ratio of the carbon fibers on the sliding surface of the slide bearing is less than 10%, however, the area ratio of the carbon fibers is such that the area ratio of the carbon fibers is an optical microscope (for any five points of the sample piece cut out from the sliding surface of the slide bearing). Observation field by 500 times): An average area ratio obtained from the area of a region having a Brightness of 75% or more in the HSB color space by image processing a portion of 589 μm in length × 442 μm in width.
The plain bearing. A plain bearing device equipped with a plain bearing.
The plain bearing is formed of a resin composition composed of aromatic polyetherketone, fluororesin, boron nitride, carbon fiber, graphite, and unavoidable impurities.
The content of the graphite with respect to the resin composition is 5% by mass or less (including 0% by mass), and the total content of the boron nitride, the carbon fibers, and the graphite is 30% by mass or less. ,
The area ratio of the carbon fibers on the sliding surface of the slide bearing is less than 10%, however, the area ratio of the carbon fibers is such that the area ratio of the carbon fibers is an optical microscope (for any five points of the sample piece cut out from the sliding surface of the slide bearing). Observation field by 500 times): An average area ratio obtained from the area of a region having a Brightness of 75% or more in the HSB color space by image processing a portion of 589 μm in length × 442 μm in width.
The plain bearing device. The slide bearing device according to claim 2, wherein the slide surface of the slide bearing can be operated in either a state of being in contact with the atmosphere or a state of being in contact with water mixed with earth and sand. The slide bearing apparatus according to claim 2 or 3, wherein the aromatic polyetherketone is a polyetherketone, a polyetheretherketone, a polyetherketoneketone, a polyetheretherketoneketone, or a combination thereof. The fluororesin is a polytetrafluoroethylene, a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, a tetrafluoroethylene / hexafluoropropylene copolymer, a tetrafluoroethylene / ethylene copolymer, or a combination thereof. , The sliding bearing device according to any one of claims 2 to 4. A pump provided with the plain bearing device according to any one of claims 2 to 5.

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