CN111406158A

CN111406158A - Sliding bearing device and pump provided with same

Info

Publication number: CN111406158A
Application number: CN201880076405.XA
Authority: CN
Inventors: 金成夏; 杉山宪一; 杉山和彦; 小宫真; 西谷要介
Original assignee: Ebara Corp; Kogakuin University
Current assignee: Ebara Corp; Kogakuin University
Priority date: 2017-11-30
Filing date: 2018-11-26
Publication date: 2020-07-10
Anticipated expiration: 2038-11-26
Also published as: JP2019100428A; WO2019107292A1; CN111406158B; JP6994194B2

Abstract

Provided are a slide bearing device for a radial bearing used in a water pump, which is provided with a slide bearing that maintains wear resistance as in the prior art when operated in water containing foreign matter (slurry) such as silt and is stably maintained in a low friction coefficient state even in a relatively high PV value range under dry lubrication conditions in which the slide bearing slides in air, and a pump provided with the slide bearing device. The sliding bearing device is provided with a sliding bearing, wherein the sliding bearing comprises aromatic polyether ketone, talc, carbon fiber and inevitable impurities, the content of the talc relative to the sliding bearing is 7-18 mass%, and the area ratio of the carbon fiber in the sliding surface of the sliding bearing is 27-35%.

Description

Sliding bearing device and pump provided with same

Technical Field

The present invention relates to a sliding bearing device using a resin material and a pump having the sliding bearing device, and more particularly to a sliding bearing device suitably used as a radial bearing of a rotary machine such as a pump and a pump having the sliding bearing device.

Background

In recent years, due to the progress of urbanization, the reduction of green space and the increase of concretization and asphalt formation of road surfaces have been promoted, and a heat island phenomenon has occurred, and a local concentrated rainstorm called a "traveling storm" has frequently occurred in urban areas. A large amount of localized rainfall is not absorbed into the ground on a concrete or asphalt road surface but is directly introduced into the canal. As a result, a large amount of rainwater flows into the drainage pump station in a short time.

In order to prevent rapid drainage of a large amount of rainwater due to such concentrated heavy rains that frequently occur, a drain pump provided in a drain pump station performs a preliminary standby operation that is started in advance before rainwater reaches the drain pump station, thereby avoiding a flooding disaster due to a delay in starting.

Fig. 1 is a partial schematic view of a vertical shaft pump for performing a preceding standby operation, the vertical shaft pump 3 is disposed in a water tank 100 of a drain pump station, the vertical shaft pump 3 is provided with an impeller 22 at the tip of a rotating shaft 10 disposed in the vertical direction, and air is sucked into the impeller 22 together with water, whereby the vertical shaft pump 3 can continue to operate (preceding standby operation) even if the water level of the water tank 100 is equal to or lower than a minimum operating water level L W L, and in the vertical shaft pump 3, a through-hole 5 is provided in the side surface of a suction bell cup (bell)27 on the inlet side of the impeller 22, and an air pipe 6 having an opening 6a that contacts with outside air is attached to the through-hole 5, whereby the supply amount of air supplied into the vertical shaft pump 3 through the through-hole 5 is changed according to the water level, and the drain amount of the vertical shaft pump 3 is controlled at or lower than the minimum operating water level L W L.

Fig. 2 is a diagram illustrating an operation state of a preceding standby operation, for example, as an application of rainwater drainage in a large city, a vertical shaft pump (a: operation in air) is activated in advance according to rainfall information or the like regardless of an intake water level, the vertical shaft pump transitions from an idle operation (operation in air) to a full-open operation (D: steady-state operation) in which water is stirred by an impeller when the water level rises from a low water level, the operation (C: operation in which the water amount is gradually increased while air supplied through a through hole is taken in with water, and the operation (D: operation in which water is gradually decreased) when the water level reaches 100% water, and further, when the water level falls from the high water level, the operation transitions from the full-open operation to the operation (C: operation in which the water amount is gradually decreased while air supplied through the through hole is taken in with water, and when the water level reaches LL W L, the operation (E: operation in which water level is not taken in suction is gradually decreased) (E: operation in air lock (rlock) is performed).

Fig. 3 is a cross-sectional view showing the entire vertical shaft pump 3 shown in fig. 1, which performs the advanced standby operation. The through-hole 5 and the air tube 6 shown in fig. 2 are not shown. As shown in fig. 3, the vertical shaft pump 3 includes: a discharge elbow 30 fixedly arranged on the pump arrangement table; a housing 29 connected to a lower end of the discharge elbow 30; a discharge bowl (bowl)28 connected to the lower end of the casing 29 and accommodating the impeller 22 therein; and a suction bell 27 connected to the lower end of the discharge bowl 28 and used for sucking in water.

One rotary shaft 10 formed by connecting two upper and lower shafts to each other by a coupling 26 is disposed at substantially the center in the radial direction of the casing 29, the discharge bowl 28, and the 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 bowl 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 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, that rotates the impeller 22. A seal 34 such as a floating seal, a gland packing (gland packing), or a mechanical seal is provided between the rotary shaft 10 and the hole provided in the discharge elbow 30, and water treated by the vertical shaft pump 3 is prevented from flowing out of the vertical shaft pump 3 by the shaft seal 34.

The driving machine is installed on land so that maintenance and inspection can be easily performed. The rotation of the drive machine is transmitted to the rotary shaft 10, and the impeller 22 can be rotated. Water is sucked in 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. 4 is an enlarged view of a conventional bearing device applied to the

bearings

32 and 33 shown in fig. 3. Fig. 5 is a perspective view of a plain bearing provided on the bearing device shown in fig. 4. As shown in fig. 4, the conventional bearing device includes a sleeve 11 made of stainless steel, ceramic, sintered metal, or surface-modified metal on the outer periphery of a rotating shaft 10. The sleeve 11 has a vickers hardness (Hv) of 800 or more and 2500 or less. A hollow cylindrical sliding 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 is configured to slide with respect to the sliding bearing 1 while facing the inner peripheral surface (sliding surface) 1a of the sliding bearing 1 with a very narrow clearance. The sliding bearing 1 is fixed to a support member 13 connected to a pump housing 29 (see fig. 3) or the like via a flange portion 12a by a bearing housing 12 made of metal or resin. As shown in fig. 5, the sliding bearing 1 has a hollow cylindrical shape, and an inner peripheral surface (sliding surface) 1a faces an outer peripheral surface 1b of the sleeve 11, and the outer peripheral surface 1b is fitted to the bearing housing 12.

The vertical axis pump 3 shown in fig. 3 operates in air when the pump is started. That is, the

bearings

32, 33 operate under dry sliding conditions without liquid lubrication. Here, the dry sliding condition refers to a condition in which the atmosphere of the

bearings

32 and 33 during the operation of the pump is in air without liquid lubrication, and the dry operation refers to an operation under such a condition. The

bearings

32 and 33 shown in fig. 4 also operate under the drainage condition in which water is supplied to the bearings. Here, the drainage condition refers to a condition that the atmosphere of the

bearings

32 and 33 during the pump operation is water in which foreign matter (slurry) such as silt is mixed, and the drainage operation refers to an operation under the condition, for example, an air-water mixing operation, a fully open operation, an airlock operation, or the like. The

bearings

32 and 33 are used under such conditions. In the vertical shaft pump 3 shown in fig. 3, two

bearings

32 and 33 are disposed with respect to the rotary shaft 10, but if the rotary shaft 10 is long, more bearings are disposed in accordance with the long length.

A sliding bearing device having a sliding bearing using a resin material is widely used for rotary machines such as turbo machines and commercial machines because of excellent lubricating performance of the resin (patent documents 1 to 4).

As a method for evaluating a resin bearing, a disc-shaped resin molded into a disc shape is rotated while a disc surface of the resin is pressed against a flat plate, and thereby a friction coefficient and a wear amount of the resin are evaluated. Further, evaluation of the coefficient of friction and the amount of wear of the resin was also performed by reciprocating a piston using the resin for the seal portion in the cylinder and sliding the seal portion and the cylinder. In such an evaluation method, a specific use condition is rarely reflected, and for example, it is rarely assumed that a foreign matter is mixed in the sliding of the bearing.

In some rotary machines such as turbomachines, a resin material is used for a sliding bearing for a radial bearing that receives a load acting in a direction perpendicular to the axial direction of a rotary shaft. The sliding bearing for the radial bearing used in the water pump is used by allowing water pumped by the pump to enter a gap (sliding portion) between the rotating body and the sliding bearing without using a lubricating oil. Therefore, when the water pump treats water mixed with foreign matter such as silt (foreign matter mixed water), the foreign matter mixed water sometimes enters the sliding surface of the sliding bearing (sliding surface of the bearing). In this case, since the centrifugal force acts in the radial direction of the sliding bearing, it is difficult to discharge the foreign matter that has entered the gap between the rotating body and the sliding bearing in the axial direction.

SiO as a main component of silt (foreign matter) as compared with a resin material₂The hardness of (2) is high, and therefore, when foreign matter intrudes into the gap between the rotating body and the sliding bearing, the resin material is worn. Therefore, there is a problem that the wear amount of the sliding bearing increases and the life of the sliding bearing becomes short in the operation of the water pump for treating the water mixed with the foreign matter.

Therefore, in many conventional methods for evaluating resin bearings, the evaluation of wear resistance under actual conditions is insufficient. In addition, in many of the conventional evaluation methods for resin bearings, even if a condition in which the contamination of foreign matter is assumed is adopted, these evaluation methods are not methods for evaluating a sliding bearing as a radial bearing. Therefore, in these evaluation methods, it is considered that the foreign matter is easily released from the sliding surface to the outside, and the influence of the retention of the foreign matter in the sliding surface is small. Therefore, these evaluation methods are not suitable for evaluating the wear resistance of a sliding bearing as a radial bearing.

In addition, the vertical shaft pump may be operated not only in a state where the bearing sliding surface is submerged, but also in a state where the bearing sliding surface is exposed to air, as in the advanced standby operation. In this way, in the case where the vertical shaft pump is operated under dry lubrication conditions in which the sliding surface of the sliding bearing is exposed to the air, a sliding bearing device having low friction under dry lubrication conditions is desired.

On the other hand, in a vertical shaft pump using a conventional sliding bearing made of a resin material, there is a case where the bearing temperature rapidly rises during the drying operation and the operation cannot be performed, and this rise in the bearing temperature becomes a problem. Fig. 6A and 6B are schematic cross-sectional views showing states of the rotary shaft 10, the sleeve 11, and the sliding bearing 1 during pump operation. In the drying operation, as the rotation speed or the bearing load increases, the frictional heat generated in the contact portion between the sliding bearing 1 used in the

bearings

32 and 33 shown in fig. 3 and the sleeve 11 attached to the rotary shaft 10 when they slide increases. Due to this frictional force, the sliding bearing 1, the rotary shaft 10, and the sleeve 11 may be locally heated to a high temperature. The hatched portions shown in fig. 6A and 6B are portions of the sliding bearing 1, the rotating shaft 10, and the sleeve 11 that have reached high temperatures.

Due to the local high temperature of the sleeve 11 attached to the rotary shaft 10, the rotary shaft 10 may be partially expanded and the rotary shaft 10 may be slightly bent as shown in fig. 6A. This makes it easy for vibrations and an increase in bearing load to occur due to interference between the rotating body (the rotating shaft 10 and the sleeve 11) and the fixed body (the sliding bearing 1) of the vertical shaft pump. That is, the rotating body is in contact with the fixed body in the unbalance direction of the rotating body, and the contact portion generates heat, thereby generating a temperature distribution in the axial cross section of the rotating shaft 10, and the rotating shaft 10 is bent due to local thermal expansion. At this time, the center of gravity of the rotating body is shifted due to the bending of the rotating shaft 10, and thus the imbalance of the entire rotating body gradually increases. In addition, the contact form between the rotating body and the sliding bearing 1 may change due to the bending of the rotating shaft 10, and the temperature gradient of the sliding bearing 1 may also change.

When the displacement due to the bending of the rotary shaft 10 is larger than the gap between the sleeve 11 and the sliding bearing 1, the sleeve 11 and the sliding bearing 1 come into contact at two points opposite in phase as shown in fig. 6B, and the bending displacement is restricted. When the rotation shaft 10 continues to rotate in this state, the thermal expansion continues further, and the pressing load against the sliding bearing 1 increases. When the pressing load applied to the sliding bearing 1 increases, the amount of heat generation increases. The increase in the amount of heat generation accelerates the thermal bending of the rotary shaft 10, and as a result, the pressing load applied to the sliding bearing 1 further increases. Falling into such a vicious circle, the temperature of the rotary shaft 10, the sleeve 11, and the sliding bearing 1 increases at an accelerated rate.

Even if the unbalance amount of the rotating body is within the allowable value, when the unbalance amount is large, the surface pressure of the sliding bearing 1 becomes large, and heat generation at the contact portion of the sliding bearing 1 and the rotating body becomes large. Therefore, the bending of the rotary shaft 10 is promoted, and the temperature of the sliding bearing 1 may be increased at an accelerated rate. In order to reduce heat generation, it is effective to reduce the friction coefficient of the sliding bearing 1. Therefore, PEEK-based plastic substrates containing carbon fibers and talc have been developed as resin materials for sliding bearings that can achieve wear resistance with a low coefficient of friction.

However, in recent years, there are many pumps that perform a drying operation, and the range of the conditions of the rotation speed (V) of the rotating shaft supported by the sliding bearing, the sliding surface pressure (P), and the range of the PV value (the rotation speed × of the rotating shaft, sliding surface pressure) are expanded to higher values.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication Hei 09-264327

Patent document 2: japanese patent laid-open No. 2013-194769

Patent document 3: japanese laid-open patent publication (Kokai) No. 2015-21551

Patent document 4: japanese patent laid-open publication 2016-205545

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a slide bearing device for a radial bearing used in a water pump, the slide bearing device including a slide bearing which maintains wear resistance as in the conventional art when operated in water containing foreign matter (slurry) such as silt and which stably maintains a low friction coefficient even in a relatively high PV value range under dry lubrication conditions in which the slide bearing slides in air, and a pump including the slide bearing device.

Means for solving the problems

Carbon fibers can increase the strength of the sliding bearing and reduce the linear expansion coefficient, and as a result, the shape change of the sliding bearing can be suppressed to a low level, and the so-called advantageous effect that the stable performance can be maintained for a long period of time can be expected.

By containing more carbon fibers, the friction coefficient can be suppressed to a lower level. In particular, the friction coefficient may repeatedly and rapidly increase and decrease during operation, and is not necessarily stable, and it is effective to contain a large amount of carbon fibers in order to keep the maximum friction coefficient at that time low.

However, if a large amount of carbon fibers are contained, the opportunity of carbon fiber discharge due to abrasion in slurry increases, and abrasion due to the discharged carbon fibers themselves is easily promoted, and therefore, the carbon fibers have a negative effect on the slurry abrasion resistance. Therefore, a certain upper limit value needs to be set for the content of the carbon fiber. That is, in order to obtain a good slurry abrasion resistance while keeping the maximum friction coefficient low, the content of the carbon fiber needs to be within a specific narrow numerical range.

Further, the friction coefficient can be effectively reduced by including talc in the material of the sliding bearing. However, talc monomers have limited effectiveness.

In the present invention, suitable ranges of carbon fibers and talc are found, and from their synergistic effects, the maximum friction coefficient can be stabilized by the effect of talc even if the content of carbon fibers is small, and a range in which wear resistance can be maintained can be determined even if the amount of carbon fibers is large.

The inventors of the present application paid attention to the area ratio of carbon fibers on the sliding surface of a bearing and the content ratio of talc in a sliding bearing, which are important factors affecting low friction properties and wear resistance, and made studies. The result is: the inventors of the present application have found that when the area ratio of carbon fibers and the content ratio of talc are within predetermined numerical ranges, the friction coefficient of the sliding bearing is low, the limit PV value is high, and the wear resistance is good.

According to one aspect of the present invention, a plain bearing arrangement is provided. The sliding bearing device is provided with a sliding bearing, wherein the sliding bearing comprises aromatic polyether ketone, talc, carbon fiber and unavoidable impurities, the content of the talc is 7 mass% or more and 18 mass% or less relative to the sliding bearing, and the area ratio of the carbon fiber in the sliding surface of the sliding bearing is 27% or more and 35% or less.

According to another aspect of the present invention, the sliding surface of the sliding bearing is configured to be operable in any one of a state of being in contact with the atmosphere and a state of being in contact with water mixed with silt.

According to another embodiment of the present invention, the aromatic polyether ketone is PEK, PEEK, PEKK or PEEKK.

According to another aspect of the present invention, the diameter of the carbon fiber is 5 μm or more and 10 μm or less.

According to another aspect of the present invention, the talc is in a flake form, has a short axis diameter of 0.1 μm or more and a long axis diameter of 15 μm or less, and has a long axis diameter of more than 1 time and 15 times or less relative to the short axis diameter.

According to another aspect of the present invention, a pump is provided. The pump is provided with the sliding bearing device.

Any two or more of the above aspects of the present invention can be combined.

Effects of the invention

According to the present invention, it is possible to provide a sliding bearing device including a sliding bearing used for a radial bearing of a water pump and stably maintained in a low friction coefficient state without impairing wear resistance even in a high PV value range in any of dry lubrication conditions for operation in water containing slurry and sliding in air, and a pump including the sliding bearing device.

Drawings

Fig. 1 is a partial schematic view of a vertical shaft pump that performs a preceding standby operation.

Fig. 2 is a diagram illustrating an operation state of the advance standby operation.

Fig. 3 is a cross-sectional view showing the entire vertical shaft pump shown in fig. 1, which performs the advanced standby operation.

Fig. 4 is an enlarged view of a conventional bearing device applied to the bearing shown in fig. 3.

Fig. 5 is a perspective view of a plain bearing provided on the bearing device shown in fig. 4.

Fig. 6A is a schematic cross-sectional view showing the states of the rotary shaft, the sleeve, and the sliding bearing during operation of the pump.

Fig. 6B is a schematic cross-sectional view showing the states of the rotary shaft, the sleeve, and the sliding bearing during the pump operation.

Fig. 7A is a graph showing the temporal changes in the bearing temperature and the friction coefficient in the drying test of the sliding bearing No.5 relating to the example of the present invention.

Fig. 7B is a graph showing the temporal changes in the bearing temperature and the friction coefficient in the drying test for the sliding bearing of No.7 relating to the comparative example.

Fig. 8 is a graph showing the relationship between the PV value and the maximum friction coefficient of the sliding bearing according to the present invention and the comparative example.

Detailed Description

The sliding bearing device according to the present embodiment has, for example, the same structure as the sliding bearing device shown in fig. 4. That is, the sliding bearing device according to the present embodiment includes the rotating shaft 10 and the sleeve 11 as the rotating body, and the sliding bearing 1 as the fixed body. 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. 5.

The sliding bearing 1 according to the present embodiment is made of a composite material of aromatic polyether ketone, talc, carbon fiber, and unavoidable impurities. The inner peripheral surface of the cylindrical sliding bearing 1 constitutes an inner peripheral surface (sliding surface) 1a of the bearing which contacts the outer peripheral surface of the sleeve 11. That is, the sliding bearing 1 is made of a material having aromatic polyether ketone, talc, and carbon fiber, which imparts low friction, high strength, and wear resistance.

In the present invention, talc is used as a solid lubricant to reduce the friction coefficient, and carbon fibers are responsible for wear resistance and a low friction coefficient.

When the sliding bearing does not include carbon fibers, the deformation of the bearing due to the thermal expansion of the bearing portion caused by the friction of the sliding surface increases after the sliding starts, and the area of the sliding surface in contact with the sleeve as the target material tends to decrease. When the area of the sliding surface in contact with the sleeve is reduced in this way, the surface pressure applied to the portion of the sliding surface in contact therewith increases, thereby exceeding the material limit PV value. If the limit PV value is exceeded, the sliding surface of the sliding bearing sinters to the sleeve, and a rapid increase in the friction coefficient and damage to the bearing occur. On the other hand, in the present invention, since the sliding surface of the sliding bearing contains carbon fibers, deformation due to thermal expansion of the sliding surface can be prevented, and the seizure resistance of the sliding bearing can be improved.

The aromatic polyether ketone preferably contains at least 1 of PEK (polyether ketone), PEEK (polyether ether ketone), PEKK (polyether ketone), and PEEKK (polyether ether ketone).

Talc is a solid lubricant and has the effect of decreasing the friction coefficient as the content is larger. The content of talc is 7 mass% or more and 18 mass% or less, preferably 10 mass% or more and 17 mass% or less, and more preferably 12 mass% or more and 15 mass% or less with respect to the sliding bearing. When the content of talc in the sliding bearing is within the above range, lubricity is improved, and the friction coefficient of the sliding surface of the sliding bearing can be reduced.

The area ratio of the carbon fibers in the sliding surface of the sliding bearing is 27% or more and 35% or less, preferably 30% or more and 34% or less, and more preferably 31% or more and 33% or less. If the area ratio of the carbon fibers in the sliding surface of the sliding bearing is within the above range, lubricity is improved, and the friction coefficient of the sliding surface of the sliding bearing can be reduced.

When both talc and carbon fiber are contained, the content of talc is 7 mass% or more and 18 mass% or less with respect to the sliding bearing, and the area ratio of carbon fiber in the sliding surface of the sliding bearing is 27% or more and 35% or less. The content of talc is preferably 9 to 15 mass%, and the area ratio of the carbon fibers is preferably 30 to 33 mass%, and more preferably 10 to 12 mass%, and the area ratio of the carbon fibers is preferably 31 to 32%. When the content of talc and the area ratio of carbon fibers are within the above ranges, the wear resistance during operation in water is excellent, and the friction coefficient is stably maintained in a low state during operation in air.

The talc content can be measured by the following method. That is, 100g of the molded sliding bearing was measured, and the molded sliding bearing was fired at 800 ℃ to decompose and volatilize components such as carbon fibers and aromatic polyether ketone, and talc was recovered as ash, and the weight of the ash was measured. Then, the ratio of the weight of ash (talc) to the weight (100g) of the sliding bearing was calculated as the talc content.

The shape of talc is preferably a scale shape, an oval shape, or the like.

The diameter of talc observed on the sliding surface 1a of the bearing is preferably 0.1 μm or more, more preferably 0.5 μm or more and 13 μm or less, most preferably 5 μm or more and 11 μm or less, and the major axis diameter is preferably 15 μm or less, more preferably 1 μm or more and 14 μm or less, and most preferably 6 μm or more and 12 μm or less, and further, the magnification of the major axis diameter with respect to the minor axis diameter is preferably more than 1 time and 15 times or less, more preferably 1 time or more and 10 times or less, and most preferably 1 time or more and 5 times or less.

The area ratio of carbon fibers can be measured by providing a smooth surface to a molded sliding bearing, randomly selecting 10 sites on the smooth surface, and taking planar images of 214 μm × in the vertical direction and 285 μm in the horizontal direction using an optical microscope (50 to 100 times objective lens, manufactured by Keyence corporation) for each site, identifying the carbon fiber portion using image analysis with the taken planar surface of 214 μm × in the vertical direction and 285 μm in the horizontal direction as an observation portion, calculating the ratio of the area of the carbon fibers to the entire area of the observation portion, and averaging the calculated values at 10 sites as the area ratio of the carbon fibers.

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 can be measured by image analysis using an optical microscope (product of Keyence corporation, objective lens 50 to 100 times) and using the same image analysis program as the above-described image analysis program used for the image analysis of talc.

The length of the carbon fibers as 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 (product of Keyence corporation, objective lens 50 to 100 times) and using the same image analysis program as the above-described image analysis program used for the image analysis of talc.

In the present invention, the sliding bearing can be produced by heating and mixing talc, aromatic polyether ketone, and carbon fiber using a biaxial kneader to prepare a resin composition, compression-molding the resin composition, and then subjecting the molded product to surface processing. Further, the sliding bearing device can be manufactured using the sliding bearing, and further, the pump can be manufactured using the sliding bearing device.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the contents described in the examples.

Examples

Example 1

In example 1, first, carbon fibers, talc, and aromatic polyether ketone were mixed by a biaxial kneader so that the area ratio of the carbon fibers and the content ratio of the talc became values shown in table 1, and pellets were produced. The obtained pellets are put into a mold, pressurized and heated, and subjected to primary processing molding, and then subjected to secondary processing machining to give a detailed shape, thereby producing a sliding bearing. Then, the obtained sliding bearing was evaluated for the wear resistance against slurry, the friction coefficient, and the limit PV value.

Here, the area ratio of the carbon fiber and the content of talc were measured by the above-described methods, and the image analysis conditions for calculating the area ratio of the carbon fiber were set as follows.

In the measurement program guide

The pixel was set to "brightness-0.66, contrast 2.65, gamma value 1.00"

Click (click) is set to "tolerance 3, edge size 1"

In table 1, only the area ratio of the carbon fiber and the content of talc are shown, and the remainder is occupied by the aromatic polyether ketone and unavoidable impurities.

[ Table 1]

Here, the evaluation of each sliding bearing in table 1 was performed in the following manner.

(abrasion speed)

First, the ratio of 1: 1 contains silica sand having an average particle diameter of about 5 μm(principal component: Si0₂) And silica sand having an average particle size of about 30 μm were put into water so as to have a concentration of 3000 mg/L to prepare water containing slurry, a bearing device including the above-described sliding bearing was immersed in the obtained water containing slurry, a planar sliding of the sliding bearing against a WC-based cemented carbide was carried out for 8 hours under a condition that the PV value was maintained at 25 ℃ and that the initial surface roughness (Ra) of the sliding bearing was 3.2, and the wear rate (μm/h) of the sliding bearing was calculated, and then the case where the wear rate of the sliding bearing was 30 μm/h or less was regarded as the presence of the slurry wear resistance, while the case where the wear rate exceeded 30 μm/h was regarded as the poor slurry wear resistance.

(coefficient of friction, maximum coefficient of friction)

The bearing device including the sliding bearing was slid in air using the device shown in fig. 4 for 2 hours at a PV value of 1.0MPa · m/s against a surface of WC-based cemented carbide having an initial surface roughness (Ra) of 3.2 without using a lubricating oil, and the friction coefficient was continuously measured at 0.5 second intervals over the 2 hours.

Then, the average value of the friction coefficient in 1 hour in the second half of the 2-hour operation was calculated as the friction coefficient of the sliding bearing. A sliding bearing having a coefficient of friction of 0.1 or less is good when the friction is small, while a sliding bearing having a coefficient of friction exceeding 0.1 is bad when the friction is large.

The maximum friction coefficient of the sliding bearing is preferably 0.1 or less as the friction coefficient can be maintained at a low level throughout the period of operation (○), while the case where the maximum friction coefficient exceeds 0.1 is sometimes considered to be defective due to an increase in the friction coefficient during operation (×).

(Limit PV value)

In the drying test using the apparatus shown in fig. 4, it was found that the temperature at the position 5mm deep from the sliding surface of the sliding bearing was good at 120 ℃ or lower even when the apparatus was operated at a PV value of 1.5MPa · m/s for 2 hours (○), while it was found that the temperature exceeded 120 ℃ as a defect (×).

Further, as the overall evaluation, the case where the wear rate, the friction coefficient, the maximum friction coefficient, and the limit PV value were all excellent was regarded as good (○), and the other cases were regarded as bad (×).

As shown in Table 1, the sliding bearings of invention examples No.1 to 6 had abrasion speeds of 30 μm/h or less and excellent abrasion resistance against slurry. On the other hand, the sliding bearings of comparative examples No.3, 4 and 6 to 9 had a wear rate of 30 μm/h or less and excellent mud wear resistance, while the sliding bearings of comparative examples No.1, 2 and 5 had a wear rate exceeding 30 μm/h and poor mud wear resistance. As is clear from the results in table 1, the slurry abrasion resistance tends to deteriorate as the area ratio of the carbon fibers and/or the content of talc increases.

The sliding bearings of invention examples nos. 1 to 6 had a friction coefficient of 0.1 or less, which was a good result. On the other hand, the friction coefficients of the sliding bearings of comparative examples nos. 1 to 7 were 0.1 or less, which is a good result, but the friction coefficients of the sliding bearings of comparative examples nos. 8 and 9 exceeded 0.1, which is a poor result. As is clear from the results in table 1, the friction coefficient fluctuates depending on the area ratio of the carbon fiber, and there is a tendency as follows: the friction coefficient increases as the area ratio of the carbon fibers decreases, and the friction coefficient decreases as the area ratio of the carbon fibers increases.

Further, the maximum friction coefficient of the sliding bearings of invention examples nos. 1 to 6 was 0.1 or less, which was a good result. On the other hand, the maximum friction coefficients of the sliding bearings of comparative examples nos. 1 and 2 were 0.1 or less, which is a good result, but the maximum friction coefficients of the sliding bearings of comparative examples nos. 3 to 9 exceeded 0.1, which is a bad result. As is clear from the results in table 1, the maximum friction coefficient varied depending on the area ratio of the carbon fibers and the content of talc, and when the area ratio of the carbon fibers was 27% or more and/or the content of talc was 7% by mass or more, the maximum friction coefficient was 0.1 or less, and favorable results were obtained.

Further, the sliding bearings of invention examples 1 to 6 and comparative examples 1 to 4 were excellent in evaluation of the limit PV value, because the temperature at the position 5mm deep from the sliding surface of the sliding bearing was 120 ℃ or less. On the other hand, the sliding bearings of comparative examples 5 to 9 were poor in the evaluation of the limiting PV value, because the temperature at the position 5mm deep from the sliding surface of the sliding bearing exceeded 120 ℃. As is clear from the results in table 1, the evaluation of the limit PV value fluctuates depending on the area ratio of the carbon fiber, and there is a tendency as follows: the area ratio of the carbon fibers is poor when the area ratio is small, and is improved when the area ratio of the carbon fibers is large.

Further, the sliding bearings of invention examples nos. 1 to 6 in which the area ratio of the carbon fibers was 27% or more and 35% or less and the content of talc was 7% by mass or more and 18% by mass or less were good in overall evaluation, while the sliding bearings of comparative examples nos. 1 to 9 in which at least one of the area ratio of the carbon fibers and the content of talc did not satisfy the above numerical value ranges were poor in overall evaluation.

Example 2

The sliding bearing of invention example No.3 of example 1 and the sliding bearing of comparative example (sliding bearing made of PEEK resin and carbon fiber of continuous fiber and containing no talc) were used as the radial bearings, i.e., the

bearings

32 and 33, of the vertical diagonal flow pump shown in fig. 3, and the actual drainage operation and drying operation of water containing foreign matter (silt) were repeated.

The results of repeating the draining operation and the drying operation were: the sliding bearing of the invention example No.3 of example 1 had a wear rate of 25.3 μm/h, which was reduced to about one third as compared with the wear rate of 84.8 μm/h of the conventional sliding bearing using PEEK resin of the comparative example. In the conventional sliding bearing using the PEEK resin of the comparative example, a rapid increase in the bearing temperature occurs in a short time during the drying operation, and it is necessary to stop the operation of the pump. On the other hand, in the sliding bearing of invention example No.3 of example 1, the pump can be stably operated without causing a rapid temperature rise. That is, by using the sliding bearing of the present invention for the

bearings

32 and 33 used under severe conditions such as repeated drainage operation and drying operation, excellent bearing characteristics can be exhibited in both air and water mixed with foreign matter.

Example 3

The sliding bearings of example No.5 of the present invention and comparative example No.7 of table 1 were mounted on the apparatus shown in fig. 4, operated for 2 hours under the operating condition of PV value of 0.5m/s · MPa, and continuously measured at 0.5 second intervals, to prepare graphs (fig. 7A and 7B) showing the time changes of the friction coefficient and the bearing temperature. Here, the sleeve 11 of the rotating shaft 10 attached to the sliding surface of the sliding bearing is a WC-based cemented carbide and has an initial surface roughness (Ra) of 3.2.

FIGS. 7A and 7B are the measurement results of example No.5 of the present invention and comparative example No.7, respectively.

As for the measurement results in fig. 7A and 7B, there was no large difference in the friction coefficient and the temperature rise on average, but in fig. 7B, a pulse-like sharp rise and a sharp fall were observed in each of the friction coefficient and the temperature, and a temperature rise was also observed in conjunction with the rise in the friction coefficient. From the results, it was found that the operation state of the sliding bearing was very unstable.

On the other hand, in fig. 7A, compared to fig. 7B, a pulse-like sharp rise and a pulse-like sharp fall are hardly observed in both of the friction coefficient and the temperature, and the rise and fall widths are very small even when there is a sharp rise and a sharp fall. From the results, it was found that the operation state of the sliding bearing was very stable.

Further, the sliding bearings of invention example No.5 and comparative example No.7 in table 1 were mounted on the device shown in fig. 4, and the PV values: the sliding bearing was operated under each of the operating conditions of 0.4, 0.5, 0.75, or 1.0 m/s.mpa for 2 hours, continuously measured at 0.5 second intervals, and the maximum friction coefficient among the friction coefficients measured in the 2-hour operation was taken as the maximum friction coefficient of the sliding bearing, to prepare a graph showing the time changes of the maximum friction coefficient and the bearing temperature for example 5 of the present invention and comparative example 7 (fig. 8).

As can be seen from fig. 8: the sliding bearing of No.5 of the present invention example had a low maximum friction coefficient, and the value thereof was stable and did not change greatly within the PV value range of 0.4 to 1.0 m/s.MPa. From the results, it is found that: the sliding bearing of the present invention can maintain the friction coefficient at a low level throughout the operation under various PV values, and can perform stable operation. On the other hand, the sliding bearing of No.7 of the comparative example exhibited a large maximum friction coefficient within the PV value range of 0.4 to 1.0 m/s.MPa, and the value varied greatly depending on the PV value. From the results, it is found that: the sliding bearing of the comparative example may have a high friction coefficient during operation, and the maximum friction coefficient may fluctuate depending on the PV value, resulting in unstable operation.

As described above, in the case of a pump including the sliding bearing of the sliding bearing device according to the present embodiment as a radial bearing, even if the underwater operation and the air operation are repeated in the drain pump station that handles water mixed with foreign matter, the low frictional property (lubricity) of the sliding bearing can be maintained while suppressing the wear of the sliding bearing.

The slide bearing device according to the present embodiment can be used for a slide bearing device that is a radial bearing operating in an air operation, and a slide bearing device that is a radial bearing operating in water into which foreign matter is mixed. The slide bearing device according to the present embodiment can be used also as a slide bearing device that is a radial bearing that repeats an operation in water in which foreign matter is mixed and an operation in air.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the technical ideas described in the claims, the specification, and the drawings. It should be noted that even a certain shape or material which is not directly described in the specification and the drawings is within the scope of the technical idea of the present invention as long as the operation and effect of the present invention are achieved.

Description of the reference numerals

Sliding bearing

Inner peripheral surface (sliding surface)

Vertical shaft pump

10.. rotating shaft

Sleeve barrel

Claims

1. A sliding bearing device provided with a sliding bearing,

the sliding bearing comprises aromatic polyether ketone, talc, carbon fiber and inevitable impurities,

the content of the talc is 7 mass% or more and 18 mass% or less with respect to the sliding bearing,

the area ratio of the carbon fibers in the sliding surface of the sliding bearing is 27% or more and 35% or less.

2. The sliding bearing device according to claim 1, wherein a sliding surface of the sliding bearing is configured to be operable in any one of a state of being in contact with the atmosphere and a state of being in contact with water in which silt is mixed.

3. A sliding bearing arrangement according to claim 1 or 2, wherein the aromatic polyether ketone is PEK, PEEK, PEKK or PEEKK.

4. A sliding bearing arrangement according to any one of claims 1 to 3, wherein the carbon fibres have a diameter of 5 μm or more and 10 μm or less.

5. A sliding bearing device according to any one of claims 1 to 4, wherein said talc is flake-like, has a short axis diameter of 0.1 μm or more and a long axis diameter of 15 μm or less, and has said long axis diameter more than 1 time and 15 times or less as large as said short axis diameter.

6. A pump provided with the sliding bearing device according to any one of claims 1 to 5.