JP6193032B2 - Sliding bearing device and pump equipped with the same - Google Patents

Description

  The present invention relates to a sliding bearing device suitably used as a radial bearing for a rotary machine such as a pump, and a pump including the same, and particularly, exhibits good friction characteristics and wear resistance even when the sliding surface is in a dry state. The present invention also relates to a bearing device having good wear resistance even in water in which foreign matter is mixed, and a pump including the same.

  Conventionally, a resin material has been widely used as a material for a bearing portion of a sliding bearing device used in a rotating machine such as a turbo machine or an office machine. Since the resin material has good lubrication performance, the resin material can be used as a material for the bearing portion of the sliding bearing device, so that the friction characteristics and wear resistance of the bearing portion can be improved.

  Here, the pump or the like used in the drainage station is not only operated in water, but in the case of a prior standby operation, the operation in the atmosphere and the operation in water are repeated. In the case of operation in the atmosphere, the bearing sliding surface of the sliding bearing device (the surface of the sliding bearing that contacts the shaft or the sleeve provided on the outer periphery of the shaft) is required to have low friction under dry conditions. In view of this requirement, there are several points to consider when a resin material is used for the bearing.

  The first point is that the resin material has a low thermal conductivity and a large linear expansion coefficient. When the pump is driven, frictional heat is generated on the sliding surface of the bearing. When the slide bearing is submerged in water, the slide surface is cooled by water, so the temperature of the slide surface is kept low. However, in dry operation that operates in air, the thermal conductivity of the slide bearing is low. Therefore, the frictional heat on the sliding surface does not diffuse and the temperature of the sliding bearing rises. In addition, since the linear expansion coefficient of the slide bearing is large, when the slide bearing expands as the temperature of the slide bearing rises, the clearance between the slide bearing and the shaft becomes small, and the slide surface seizes due to friction. There is a fear.

  The second point is that many of the resin materials currently used are a mixture of fluororesin-based or PEEK (aromatic polyetherketone) -based resin materials with carbon fibers to increase strength. It is. When the mixing ratio of the carbon fiber is increased to increase the strength of the resin material, the wear resistance in water in which foreign substances are mixed decreases and molding becomes difficult.

  The third point is that the resin material used for the slide bearing may contain a fluororesin and graphite. In this case, the friction coefficient of the bearing surface is reduced. However, when the mixing ratio increases, the strength of the sliding bearing decreases and it becomes difficult to form. Moreover, when the mixing ratio of the fluororesin increases, the linear expansion coefficient of the slide bearing tends to increase.

  As described above, depending on the mixing ratio of these materials used in the slide bearing, physical properties such as friction coefficient, strength, and linear expansion coefficient due to the addition of each material may be in a trade-off relationship with each other. Therefore, it is difficult to predict the mixing ratio of resin materials and the like that have appropriate physical properties.

The water handled by the pump used at the drainage station includes earth and sand. Since SiO ₂ which is the main component of this earth and sand is very hard compared to the resin material, when the resin material is used for the pump slide bearing, the bearing slide surface is submerged in water, so it will penetrate into the slide surface. The sliding bearing is cut and worn by the earth and sand. For this reason, there exists a problem that the lifetime of the slide bearing formed with a resin material becomes short, and a countermeasure against wear is required.

Patent No. 3678490 JP 2006-233786 A

  Since the present invention has been made in view of the above-described conventional problems, a first object thereof is to provide a slide bearing device having a good moldability and a linear expansion coefficient and a friction coefficient that are kept low during atmospheric operation. To provide a pump. The second object is to provide a sliding bearing device having good wear resistance in operation in water mixed with foreign matter, and a pump including the same.

  In order to achieve the above object, a sliding bearing device according to an aspect of the present invention includes a sliding bearing, and the sliding bearing includes a fluororesin, an aromatic polyether ketone, carbon fiber, graphite, and unavoidable impurities, In the sliding surface of the bearing, the fluororesin has an area ratio of 2% to 10%, the carbon fiber has an area ratio of 4% to 17%, and the graphite is 5% to 15%. The aromatic polyether ketone and the inevitable impurities occupy the remaining area.

In the sliding bearing device according to another aspect of the present invention, the linear expansion coefficient of the sliding bearing is 40 × 10 ⁻⁶ / ° C. or less.

  A sliding bearing device according to another embodiment of the present invention is configured to be operable in a state where the sliding surface of the sliding bearing is in contact with the atmosphere.

  In the plain bearing device according to another aspect of the present invention, the fluororesin is PTFE, PFA or FEP.

  In the plain bearing device according to another aspect of the present invention, the aromatic polyether ketone is PEK, PEEK, PEKK, or PEEKK.

  In the plain bearing device according to another aspect of the present invention, the carbon fiber has a diameter of 5 μm or more and 15 μm or less.

  In the plain bearing device according to another aspect of the present invention, the fluororesin has a diameter of 2 μm or more and 30 μm or less.

  In order to achieve the above object, a sliding bearing device according to an aspect of the present invention includes a sliding bearing, and the sliding bearing includes a fluororesin, an aromatic polyether ketone, carbon fiber, graphite, and unavoidable impurities, The hardness of the sliding surface of the bearing is 63 or more and 86 or less in the type D durometer hardness.

  The sliding bearing device according to another aspect of the present invention is configured to be operable in a state where the sliding surface of the sliding bearing is in contact with water mixed with earth and sand.

In the sliding bearing device according to another aspect of the present invention, in the sliding surface of the sliding bearing, the fluororesin has an area ratio of 2% to 10% and the carbon fiber has an area of 4% to 17%. The graphite has an area ratio of 5% to 15%, and the aromatic polyether ketone and the inevitable impurities occupy the remaining area.

  In order to achieve the above object, a pump according to an aspect of the present invention includes any one of the sliding bearing devices.

  ADVANTAGE OF THE INVENTION According to this invention, while keeping a linear expansion coefficient and a friction coefficient low, a slide bearing apparatus with favorable moldability and a pump provided with the same can be provided. Moreover, according to this invention, a sliding bearing apparatus with favorable abrasion resistance and a pump provided with the same can be provided.

It is sectional drawing which shows the vertical mixed flow pump which concerns on one Embodiment of this invention. It is an enlarged view of a plain bearing device concerning one embodiment of the invention in this application. It is a perspective view which shows the slide bearing which concerns on one Embodiment of this invention. It is a figure which shows the evaluation result of the abrasion rate in the evaluation test of Example 2, and a friction coefficient. 6 is a graph in which the wear rate of a bearing is plotted for each type D durometer hardness evaluated in Example 3. FIG.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a sliding bearing device according to an embodiment of the invention and a pump including the same will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a vertical mixed flow pump which is an example of a pump used in a drainage station, which includes a plain bearing device according to the present embodiment.

  As shown in FIG. 1, the vertical mixed flow pump has a discharge elbow 30 installed and fixed on the pump installation floor, a suspension pipe 29 connected to the lower end of the discharge elbow 30, and a lower end of the suspension pipe 29. A discharge bowl 28 for storing an impeller 22 to be described later is connected, and a suction bell 27 is connected to the lower end of the discharge bowl 28 for sucking water.

In the vertical mixed flow pump, shafts 25 and 25 ′ connected to each other by a shaft coupling 26 are disposed at substantially radial center portions of the suspension pipe 29, the discharge bowl 28 and the suction bell 27. The shafts 25 and 25 ′ are supported by the upper bearing 32 and the lower bearing 33. An impeller 22 for sucking water into the pump is connected to one end side (suction bell 27 side) of the shafts 25 and 25 '. The other ends of the shafts 25 and 25 ′ are connected to a driving motor (not shown) that rotates from the hole provided in the discharge elbow 30 to the outside of the vertical mixed flow pump and rotates the impeller 22.
A floating seal 34 is provided between the shafts 25, 25 ′ and a hole provided in the discharge elbow 30, so that water handled by the vertical mixed flow pump flows out of the vertical mixed flow pump. Is prevented.

  The drive motor is provided on land so that maintenance and inspection can be easily performed. The rotation of the drive motor is transmitted to the shafts 25 and 25 ′, and the impeller 22 can be rotated. By the rotation of the impeller 22, water is sucked from the suction bell 27, passes through the discharge bowl 28 and the suspension pipe 29, and is discharged from the discharge elbow 30.

  The vertical mixed flow pump shown in FIG. 1 is operated in a state where there is no fluid inside the pump when the pump is started, that is, in a dry condition. In addition, during steady operation after startup, the pump is operated in a state where there is water mixed with foreign matter inside the pump.

FIG. 2 is an enlarged view of the plain bearing device for the bearings 32 and 33 according to the present embodiment. As shown in the figure, a metal sleeve 11 made of stainless steel or the like is provided on the outer periphery of the shaft 25 (25 ′). A slide bearing 1 is provided on the outer periphery of the sleeve 11, and the outer peripheral surface of the sleeve 11 is configured to slide with the inner peripheral surface (slide surface) of the slide bearing 1. The plain bearing 1 is fixed to the casing 13 of the pump via a collar portion 12a by a bearing case 12 made of metal.
The sleeve material 11 is made of a metal having a Vickers hardness of 200 or more and 2500 or less, and is preferably any one of ceramic, cemented carbide, and cermet in addition to stainless steel.

FIG. 3 is a perspective view showing the plain bearing 1 in FIG.
As shown in the drawing, the slide bearing 1 of the slide bearing device according to the present embodiment has a hollow cylindrical shape.

By the way, as a bearing material of the sliding bearing 1 shown in FIGS. 2 and 3, PEEK (polyetheretheretherketone) resin is generally used as a base material. As described above, such a resin material has a low thermal conductivity and a large linear expansion coefficient. When the linear expansion coefficient of the bearing material is large, the temperature rises due to sliding frictional heat during dry operation, and the bearing material expands greatly, and the clearance between the sliding surface of the sliding bearing 1 and the sleeve 11 (shafts 25 and 25 ') is small. Thus, the sliding surface of the sliding bearing 1 may be seized due to friction.
On the other hand, mixing of carbon fibers (carbon fibers) into an aromatic polyetherketone-based resin material such as PEEK resin has the effect of improving the strength of the bearing material and reducing the linear expansion coefficient.

The clearance between the slide surface of the slide bearing 1 and the sleeve 11 is usually on the order of 0.1 mm or less, the upper limit temperature of the resin material used for the slide bearing 1 is about 120 ° C., and is assumed during dry operation. In consideration of the temperature rise of the bearing, the clearance between the sliding surface and the sleeve 11 is maintained, and in order to prevent the sliding surface from being seized, the linear expansion coefficient of the sliding bearing 1 is 40 × 10 ⁻⁶ / ° C. or less. Thus, it is necessary to adjust the amount of carbon fiber mixed.
However, when the mixing ratio of the carbon fiber increases, the strength of the bearing material increases and becomes hard, so that wear resistance is lowered and molding may be difficult.

  On the other hand, the mixing of the fluororesin and graphite into the aromatic polyetherketone-based resin material has the effect of reducing the friction coefficient of the resin material. However, as described above, when the amounts of the fluororesin and graphite are increased, the strength of the resin material is lowered, and there is a possibility that molding becomes difficult. Moreover, when the mixing ratio of the fluororesin increases, the linear expansion coefficient of the resin material tends to increase.

Therefore, the inventors have found a suitable sliding bearing used in the sliding bearing device according to the present invention. That is, the slide bearing contains fluororesin, aromatic polyetherketone, carbon fiber, graphite, and inevitable impurities, and the fluororesin has an area ratio of 2% or more and 10% or less on the slide surface of the slide bearing. Has an area ratio of 4% or more and 17% or less, graphite has an area ratio of 5% or more and 15% or less, and when the aromatic polyether ketone and inevitable impurities occupy the remaining area, the linear expansion coefficient and It has been found that the coefficient of friction is low, the moldability and wear resistance are good, and good bearing performance can be maintained during operation in the atmosphere.
Here, the area ratio is an average value of the ratio of the area occupied by each constituent material obtained by providing a smooth surface on the molded bearing, photographing several places on the surface with a microscope, and analyzing the observation part. It is.

PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene / hexafluoropropylene polymer) are used as the fluororesin used in the sliding bearing material according to the present invention. Etc.) are preferred.
In addition to PEEK, PEK (polyetherketone), PEKK (polyetherketoneketone), PEEKK (polyetheretherketoneketone), etc. may be used as the aromatic polyetherketone used for the plain bearing material according to the present invention. preferable.

Hereinafter, examples of the resin material used for the slide bearing of the slide bearing device according to the present invention will be described.
In this example, a plurality of resin test pieces (molded articles) containing fluororesin, aromatic polyetherketone, carbon fiber, graphite and inevitable impurities were prepared at the area ratio of each constituent material shown in Table 1 and evaluated. It was. Here, the area ratio is determined by the constituent materials obtained by providing a smooth surface on the molded product, photographing several places on the surface with a microscope, and analyzing the image of the observed portion (1.4 mm × 1.0 mm). This is the average value of the area ratio.
In Table 1, only the area ratios of fluororesin, graphite, and carbon fiber are described, but the remaining area is occupied by aromatic polyether ketone and inevitable impurities.

As shown in Table 1, the evaluation items in this example were formability, linear expansion coefficient of the molded product, and friction coefficient when sliding under dry conditions.
In the evaluation of moldability, it was evaluated whether or not pores were generated by molding by a special method in which a pellet-shaped resin raw material was heated and baked and solidified in a mold. The linear expansion coefficient was calculated based on the amount of thermal expansion when the temperature of the molded product was raised from 20 ° C to 140 ° C. In the evaluation of the friction coefficient, a resin test piece of 20 × 20 × 5 (mm) was pressed against a cylindrical test piece of φ20 made of cemented carbide with a load of 500 g, and the peripheral speed was 0.5 m / s for 30 minutes. Sliding against cemented carbide.
As an evaluation, the one having a linear expansion coefficient of 40 × 10 ⁻⁶ / ° C. or less and a friction coefficient of 0.2 or less was regarded as acceptable. When the friction coefficient exceeds 0.2, the bearing temperature exceeds 100 ° C., and the friction behavior becomes unstable.

  As shown in Table 1, the area ratio of each component on the surface of the molded product for which pass evaluation was obtained is 2% to 10% for fluororesin, 5% to 15% for graphite, and 4% to 17 for carbon fiber. % Or less.

Next, an evaluation test on the friction coefficient and the wear rate when the bearing of the slide bearing device according to the present invention was slid under dry conditions was performed.
Table 2 is a table showing the area ratio (%) of each component of the resin material constituting the bearing used in the evaluation test. The resin material of this invention in a table | surface is a resin material which has an area ratio contained in the area ratio of each component by which the pass evaluation demonstrated in Example 1 was obtained. Resin materials 1 to 4 are comparative examples for the resin material used in the slide bearing of the slide bearing device according to the present invention.

  In the evaluation test in this example, a bearing having a bearing inner diameter of 65 mm and a bearing width of 20 mm made of each resin material shown in Table 2 is used under dry lubrication conditions in which a liquid film such as a water film or an oil film is not on the sliding surface. The wear speed and friction coefficient were measured and evaluated when the bearing surface pressure (bearing load / (bearing inner diameter × bearing width)) was 0.1 MPa and the sliding speed was 4.0 m / sec for 2 hours.

FIG. 4 is a diagram showing the evaluation results of the wear rate and the friction coefficient in the evaluation test of this example. The vertical axis represents the bearing wear rate (μm / h) and the friction coefficient.
As illustrated, the resin material 1 has a smaller friction coefficient than the resin material of the present invention, but has a very high wear rate.
In the resin material 2, the wear rate is substantially equal to that of the resin material of the present invention, but the friction coefficient is larger than that of the resin material of the present invention.
In the resin material 3, both the wear rate and the friction coefficient are large as compared with the resin material of the present invention.
With resin material 4, the frictional force increased rapidly soon after the test was started, making it difficult to continue the test and making measurement impossible.

From the results of this example, it can be seen that the resin material of the present invention exhibits both a low wear rate and a low coefficient of friction, and exhibits a very good dry lubrication effect.
In addition, the diameter of the carbon fiber added in the resin material of the present invention in this example is 5 μm or more and 15 μm or less, and the diameter of the fluororesin is 2 μm or more and 30 μm or less. Here, the diameter of the fluororesin refers to the diameter of the fluororesin particles.

As described above, according to the sliding bearing device according to the present invention, it is possible to reduce the coefficient of friction and the wear rate while ensuring the formability, and to improve the friction and wear characteristics in the atmospheric operation. . In addition, since the linear expansion coefficient of the bearing is 40 × 10 ⁻⁶ / ° C. or less, the amount of expansion due to an increase in the temperature of the bearing in the atmospheric operation can be reduced, and the bearing due to a narrow gap between the bearing and the spacer. Can be prevented.

Next, the sliding bearing device according to the present embodiment and the pump including the same that have good wear resistance even when operated in water containing foreign matter such as earth and sand will be described.
As described above, SiO ₂ which is the main component of earth and sand has a high hardness, and when a resin material is used for the sliding bearing of the pump, the bearing is cut and worn by the earth and sand that has entered the bearing sliding surface.

Thus, the inventors have found a slide bearing suitable for operation in water containing foreign matter.
That is, when the sliding bearing contains fluororesin, aromatic polyetherketone, carbon fiber, graphite and inevitable impurities, and the hardness of the sliding surface of the sliding bearing is 63 or more and 86 or less in the type D durometer hardness, It has been found that the wear resistance of the sliding bearing is good even during operation in water containing foreign matter.

Embodiments of the sliding bearing device according to the present invention will be described below.
In this example, an evaluation test was conducted on the wear rate when the slide bearing of the slide bearing device according to the present invention was slid in water in which foreign matter, that is, SiO ₂ which is the main component of earth and sand was mixed.

In the evaluation test in this example, a plurality of bearings were prepared by changing the mixing ratio of aromatic polyether ketone, fluororesin, carbon fiber, and graphite, and the type D durometer hardness and wear rate of each bearing were measured.
In the wear test, a bearing having a bearing inner diameter of 65 mm and a bearing width of 20 mm was put into water having a foreign matter concentration of 3000 mg / L, and the bearing surface pressure was 0.12 MPa and the sliding speed was 5.0 m / sec. Foreign matter contained in water contains 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 in a ratio of 1: 1.

FIG. 5 is a graph in which the wear rate (μm / h) of the bearing is plotted for each type D durometer hardness evaluated in this example. The horizontal axis indicates the type D durometer hardness, and the vertical axis indicates the wear rate of the bearing.
As shown in FIG. 5, it can be seen that the wear resistance of the bearing in the foreign matter mixed water has a correlation with the hardness of the material (type D durometer hardness). That is, when the type D durometer hardness is greater than 86, the wear rate increases rapidly. However, when the type D durometer hardness is 86 or less, the wear rate is very low, and when the type D durometer hardness is 63 to 86, the value is small. The lower the wear rate.

  As described above, in the present invention, the hardness of the plain bearing is 63 or more and 86 or less in the type D durometer, so that it has high wear resistance even in water in which foreign matter is mixed, and is excellent. The sliding performance can be maintained. In the bearing of the sliding bearing device according to the present invention, since the resin material has sufficient hardness to maintain the structure of the bearing and has an appropriate degree of softness, foreign matter that has probably entered between the sliding surfaces is probably present. It is considered that the wear resistance is improved because the foreign material does not remain stuck in the resin material and is gradually discharged out of the sliding surface.

  Finally, the area ratio of each constituent component is an area ratio at which a pass evaluation was obtained in the evaluation test described in Example 1, fluororesin: 2% to 10%, carbon fiber: 4% to 17% Graphite: 5% to 15%, aromatic polyetherketone and inevitable impurities: remaining area, and a type D durometer hardness of 63 to 86 was made to make a plain bearing shown in FIG. It was incorporated in the slide bearing 1 of the slide bearing devices 32 and 33 of the flow pump, and the drainage of water containing actual foreign substances, that is, earth and sand, and the dry operation were repeated.

  As a result, the wear rate of the sliding bearing 1 is reduced to one-fourth that of a sliding bearing using conventional PEEK bearing resin, and the pump is stably operated with its friction coefficient kept constant. I was able to.

  As described above, if the pump is provided with the slide bearing device according to the present invention, even if the underwater operation and the atmospheric operation are repeated in the drainage station that treats the wastewater mixed with foreign matter, the wear of the bearing And the low friction (lubricity) of the bearing can be maintained.

  The present invention is not limited to the embodiment described above, and can be used for a sliding bearing device that is operated in an atmospheric operation or a sliding bearing device that is operated in water mixed with foreign matter. Further, the present invention can be used for a bearing device in which operation in water in which foreign matters on the bearing sliding surface are mixed and operation in the atmosphere are repeated.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible. Note that any shape or material not directly described in the specification and drawings is within the scope of the technical idea of the present invention as long as the effects and advantages of the present invention are achieved.

DESCRIPTION OF SYMBOLS 1 ... Slide bearing, 11 ... Sleeve, 12 ... Bearing case, 12a ... Collar part, 13 ... Casing, 22 ... Impeller, 25, 25 '... Shaft, 26. ··· Shaft coupling, 27 ··· Suction bell, 28 ··· Discharge bowl, 29 ··· Hanging tube, 30 ··· Discharge elbow, 32 · · · Upper bearing, 33 · · · Lower bearing, 34 · ..Floating seal



FIG.

Claims (7)

A sliding bearing device having a sliding bearing,
The plain bearing includes a fluororesin, an aromatic polyether ketone, carbon fiber, graphite and inevitable impurities,
In the sliding surface of the sliding bearing, the fluororesin has an area ratio of 2% to 10%, the carbon fiber has an area ratio of 4% to 17%, and the graphite is 5% to 15%. Having the following area ratio, the aromatic polyether ketone and the inevitable impurities occupy the remaining area ,
The sliding surface has a sliding surface hardness of 63 to 86 in terms of type D durometer hardness,
The sliding surface of the sliding bearing, that is operable configured in contact with water condition and soil in contact with the atmosphere is mixed, sliding bearing device.   The sliding bearing device according to claim 1, wherein the sliding bearing has a linear expansion coefficient of 40 × 10 −6 / ° C. or less. The plain bearing device according to claim 1 or 2 , wherein the fluororesin is PTFE, PFA, or FEP. The aromatic polyether ketone, PEK, PEEK, is PEKK or PEEKK, sliding bearing device according to any one of claims 1 to 3. The carbon fiber has a diameter is 5μm or more 15μm or less, a sliding bearing device according to any one of claims 1 to 4. The sliding bearing device according to any one of claims 1 to 5 , wherein the fluororesin has a diameter of 2 µm to 30 µm. The pump provided with the slide bearing apparatus as described in any one of Claims 1 thru | or 6 .

Images