KR20160078863A - Underwater sliding member - Google Patents

Abstract

Provided is an underwater sliding member capable of preventing damage to the surface of a lubrication plug, which becomes a sliding surface, during use. The underwater sliding member comprises: a metal base body having the sliding surface; and the lubrication plug. The metal base body has a plurality of holes or recesses formed on the sliding surface thereof. The lubrication plug is embedded in the hole or the recess. The lubrication plug is made of polyethylene. The molecular weight of the polyethylene is preferably 200,000 or more. The lubrication plug contains 20 vol% or less of at least one resin selected from phenol, polyamide, polyimide, polyamide-imide, polytetrafluoroethylene, polyphenylene sulfide, and polyoxyethylene benzoyl and 1 vol% or less of a coloring agent.

Description

[0001] UNDERWATER SLIDING MEMBER [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater sliding member used in water for use in a sliding portion of a water dam, a drainage pump, and the like. More specifically, the present invention relates to an underwater sliding member in which a lubricating plug is embedded in a metal base.

The underwater sliding member is used under low speed and high load conditions such as a sliding portion of a watercourse of a dam and a drainage pump. For example, a counterpart material such as a shaft is immersed in water, As shown in FIG. As such an underwater sliding member, it is known that a plurality of holes or recesses are formed in a metal base, and a lubrication plug is embedded in the hole or recess.

Patent Document 1 discloses a structure of a lubricating plug (pellet) used in a state of being embedded in a metal base, in which a concave portion is provided in a pellet matrix portion made of graphite, and a solid lubricant such as paraffin or graphite and a mixture of polyethylene are filled have. Graphite is physically adsorbed by water, and it is considered that the cleavage strength of graphite itself is weakened and the coefficient of friction is lowered. When the temperature of the sliding surface rises due to friction during use, polyethylene and paraffin constituting the lubricating plug are thermally expanded, and further, the paraffin becomes a liquid phase from the solid phase (solid phase) By volume expansion, it is described that the mixture protrudes from the sliding surface and is pressed against the surface of the counter material, so that a solid lubricant such as graphite is easily supplied between the sliding surfaces.

Further, in Patent Document 2, the sliding member using the lubricating plug including graphite has insufficient ability to form a film on the sliding surface. Therefore, it is preferable to use polyethylene, wax and melamine cyanurate, which contain melamine cyanurate in place of graphite A lubricating plug is proposed. Melamine cyanurate, like graphite, is considered to have a layered structure and wall characteristics, and is said to have an action of improving the abrasion resistance of sliding members.

On the other hand, Patent Literature 3 discloses a lubricating oil which is not a lubricating plug used for a sliding member used in water, but it is a lubricating oil which contains no graphite and is obtained by mixing lubricating oil, ultrahigh molecular weight polyethylene and a thermoplastic resin having a melting point higher than that of the ultrahigh molecular weight polyethylene, There is proposed a lubricating plug having a plurality of openings and containing high-molecular-weight polyethylene containing lubricating oil and lubricating oil.

Japanese Patent Application Laid-Open No. 51-46668 International Publication No. 2004/046285 Japanese Unexamined Patent Application Publication No. 2012-92241

The sliding member of Patent Document 1 has a problem that the surface of the lubricating plug on the sliding surface of the sliding member (that is, the mixture of paraffin, solid lubricant, and polyethylene) is damaged during use in water, and the sliding property is deteriorated. In the sliding member, the sliding surface of the solid lubricant is flush with the sliding surface of the metal base before use, but when the temperature of the sliding surface rises due to friction at the time of use, the lubricating plug is thermally expanded and buried in the metal base The lubricating plug protruding from the sliding surface is pressed against the surface of the mating member. Due to sliding of the mating member and the lubricating plug, a force in a direction parallel to the surface of the portion protruding from the surface of the metal base is applied and deformation occurs. This deformation first causes cleavage (shearing) also in the graphite powder (solid lubricant) present in the lubricating plug, and shearing also occurs in the polyethylene which has retained the graphite powder. By this front end, the lubricating plug near the surface is removed. Alternatively, stress concentration occurs near the boundary between the portion of the lubricating plug protruding from the surface (sliding surface) of the metal base and the portion confined to the hole of the metal base, and cleavage (shear) occurs in the graphite powder near the boundary, In addition, shearing occurs in the polyethylene which has retained the graphite powder, which causes the damage that the lubricating plug is removed.

When the temperature of the sliding surface rises during use, the paraffin contained in the lubricating plug of Patent Document 1 becomes a liquid phase from the solid phase. The liquefaction of the paraffin causes a decrease in the strength of the lubricating plug, It is considered to be one of the factors that make it easy to get up. When the lubricating plug is damaged, when the operation of the apparatus is stopped and the temperature of the sliding member is lowered, the surface of the lubricating plug is positioned inside the surface (sliding surface) of the metal base. Then, when the operation is resumed, since there is no lubricating plug on the surface of the metal base, the surface of the metal base and the surface of the mating member are in direct contact with each other, and sticking is likely to occur.

The lubricating plug of Patent Document 2 contains melamine cyanurate. Like melamine cyanurate, the melamine cyanurate has a layered structure and wall characteristics, and therefore is easy to shear easily. In the same mechanism as the lubricating plug containing graphite, The surface that is the sliding surface of the sliding door is liable to be damaged.

The lubrication plug of Patent Document 3 can not be applied to an underwater sliding member. Even if this lubrication plug is applied to the underwater sliding member, the water is present between the sliding surface of the sliding member and the surface of the mating member, so that the lubricating oil contained in the lubricating plug is not supplied to the sliding surface. Further, since the lubricating plug has a hollow portion for containing the lubricating oil, the strength thereof is weak, and the surface of the lubricating plug which is the sliding surface of the lubricating plug tends to be damaged at the time of use.

It is an object of the present invention to solve the above-described problems of the prior art and to provide an underwater sliding member in which damage to a surface serving as a sliding surface of a lubrication plug is unlikely to occur during use.

An underwater sliding member according to the present invention includes a metal base having a sliding surface and a lubrication plug. The metal base is provided with a plurality of holes or recesses that open on the sliding surface, and a lubricating plug is embedded in the holes or recesses. In the present invention, the lubricating plug is made of polyethylene.

The molecular weight of the polyethylene is preferably 200,000 or more.

The lubricating plug may further contain at least 20% by volume of at least one resin selected from the group consisting of phenol, polyamide, polyimide, polyamideimide, polytetrafluoroethylene, polyphenylene sulfide and polyoxybenzoyl, Lt; / RTI >

Further, the lubricating plug may further contain not more than 1% by volume of a coloring agent.

The inner circumferential surface of the metal base may be a cylindrical surface, which is a sliding surface, or a flat surface.

Other objects, features and advantages of the present invention will become apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.

1 is a perspective view of an embodiment of an underwater sliding member according to the present invention;
2 is a sectional view of the sliding member in the vicinity of the sliding surface of the underwater sliding member of Fig. 1;
3 is a sectional view of the vicinity of a sliding surface of another embodiment of the underwater sliding member according to the present invention.

1 shows a perspective view of an embodiment of an underwater sliding member according to the present invention.

The underwater sliding member 1 has a cylindrical metal base 2 and a plurality of cylindrical holes 3 penetrating the thickness of the wall between the inner and outer circumferential surfaces of the metal base 2, Shaped lubrication plug 4 embedded in a cylindrical body. The inner peripheral surface of the metal base 2 becomes the sliding surface 5 of the sliding member. The composition of the metal base 2 is not particularly limited, but various alloys such as copper alloys and iron alloys can be used and can be produced by sintering or casting.

The size (inner diameter, outer diameter, width) of the metal base 2 is not limited, and can be set according to the dimension of the sliding portion of the apparatus in which the underwater sliding member 1 is used. The diameter of the hole 3 on the sliding surface 5 of the sliding member 1 is about 3 to 30 mm and the area ratio of the opening of the plurality of holes 3 on the sliding surface 5 Is 10% to 50%, but it is not limited to this dimension and area ratio but may be changed.

The lubricating plug 4 is made of a polyethylene resin. The lubricating plug 4 can be produced by injection molding a powder of polyethylene resin as a raw material into a cylindrical shape. The manufacturing method of the lubricating plug is not limited to this and may be other methods such as extrusion molding, compression molding and the like.

The dimensions and shape of the lubrication plug 4 are made to match the diameter and shape of the hole 3 of the metal base 2. The lubrication plug 4 is buried in the hole 3 of the metal base 2 and then subjected to machining such as cutting and grinding on the inner circumferential surface of the metal base 2 so that the surface of the metal base 2, The sliding surface 5 in which the surface of the substrate 4 is in a plane, that is, in a state in which there is no step is formed. In addition, the inner peripheral surface of the metal base 2 may be formed as the sliding surface 5 without machining such as cutting and grinding.

Since the polyethylene resin has a low water absorption rate and high deformability, it is used as a lubricating plug of the sliding member for underwater according to the present invention. When the temperature of the sliding surface 5 of the sliding member 1 rises at the time of sliding, the lubricating plug 4 made of polyethylene resin thermally expands and the sliding surface 5 of the sliding member 1 (the surface of the metal base 2 To contact the surface of the mating member. The sliding surface 5 of the metal base 2 and the surface of the mating member are formed with a gap between their surfaces so that a water film is formed in the gap and the metal base 2 and the mating member can be prevented from being in direct contact with each other.

The lubrication plug 4 is a single-phase structure made of a polyethylene resin, and shearing is unlikely to occur even when the lubrication plug 4 deforms in contact with the mating member during sliding.

Since the lubricating plug 4 does not include a wall-like substance such as graphite contained in the lubricating plug of the prior art, the lubricating plug 4, which protrudes from the sliding surface 5 by sliding with the counterpart, Even if a load is applied to the lubrication plug, the shearing is hard to occur in the lubrication plug.

Further, since the polyethylene resin has a single-phase structure, even if the lubricating plug 4 is deformed due to sliding with the mating member, a stress concentration region is not formed therein.

(Graphite or the like) having a deformation resistance different from that of the polyethylene resin is dispersed in the polyethylene resin as in the prior art, when the deformation occurs in the lubricating plug, the material having a deformation resistance different from that of the polyethylene resin Shear stress is generated between the phase and the polyethylene resin phase, and shearing tends to occur.

The lubricating plug 4 of the present invention thermally expands when the temperature of the sliding surface 5 of the underwater sliding member 1 rises and the lubricating plug 4 thermally expands. However, since the lubricating plug 4 is a single- The shear stress due to the difference in the amount of thermal expansion does not occur. (Graphite or the like) having a coefficient of thermal expansion different from that of the polyethylene resin is dispersed in the polyethylene resin as in the prior art, the temperature of the sliding surface of the sliding member is increased, Shearing stress is generated at the interface due to the difference in the amount of thermal expansion, so shearing tends to occur.

The lubricating plug 4 of the present invention is a lubricating plug 4 in which one or more resins selected from phenol, polyamide, polyimide, polyamideimide, polytetrafluoroethylene, polyphenylene sulfide, By volume or more and 20 volume% or less, so that the strength or the like of the lubricating plug 4 can be adjusted. Particularly, even when the temperature of the lubricating plug 4 rises due to friction with the mating member during use of the underwater sliding member 1, the strength can be maintained.

The difference between the thermal expansion coefficient of the selective additive resin and the thermal expansion coefficient of the polyethylene resin is small compared to the difference in thermal expansion coefficient between various inorganic compounds such as graphite and the polyethylene resin. A slight shear stress is generated. The amount of these selective resins contained in the lubricating plug 4 should be 20% by volume or less, more preferably 10% by volume or less in order to reduce the influence of the shear stress due to the difference in thermal expansion coefficient between the polyethylene resin and the selective resin .

As the polyethylene resin, various commercially available polyethylene resins can be used. The polyethylene resin preferably has a molecular weight of 200,000 or more. This is because the strength of the lubrication plug increases, and the amount of wear of the surface of the lubrication plug at the time of sliding can be reduced. As the polyethylene resin having a molecular weight of 200,000 or more, for example, the following can be used.

HI-ZEX MILLION (registered trademark) (molecular weight of 500,000 or more) manufactured by Mitsui Chemicals, Inc.

LUBMER (registered trademark) (molecular weight of 200,000 or more) manufactured by Mitsui Chemicals, Inc.

SUNFINE (registered trademark) UH (molecular weight: 3.5 million or more) manufactured by Asahi Chemical Industry Co.,

The lubricating plug 2 may contain not more than 1% by volume of a coloring agent to perform any coloring. As the coloring agent, any conventional coloring agent used for coloring the resin may be used, and carbon black, iron oxide, chromium oxide, or the like can be used. However, the coloring agent is not limited thereto, and various commercially available coloring agents can be used. Further, since carbon black does not have wall characteristics unlike graphite, occurrence of shear stress is limited.

Fig. 3 is a sectional view of the vicinity of the sliding surface of another embodiment of the underwater sliding member according to the present invention.

In this example, the metal base 2 is provided with a recess 3 'which is open only to the sliding surface 5 and not to the outer circumferential surface, instead of the through hole, and the lubricating plug 4 ') Is buried. 1 and 2, except that the recess 3 'is formed in the metal base 2 instead of the hole, as described with reference to Figs. 1 and 2. Fig.

The underwater sliding member of the present invention is not limited to the structure shown in Figs. 1 to 3, and other modifications are possible. For example, the metal base of the underwater sliding member is not limited to a cylindrical shape, and may be a semi-cylindrical shape, a flat plate shape, or other shapes. The hole or concave portion of the metal base is not limited to the cylindrical shape but may be an elliptical column or prismatic shape. Naturally, the lubrication plug has a shape matched to the hole or concave portion of the metal base.

In addition, unlike the present invention, the underwater sliding member covered with the polyethylene resin layer on the entire surface of the smooth inner peripheral surface of the metal base 2, without forming the hole 3 in the metal base 2, There is a problem that shear occurs at the interface between the surface of the metal substrate 2 and the polyethylene resin layer.

(Example)

The sliding members of Examples 1 to 3 and Comparative Examples 1 to 4 were produced by the following steps.

Manufacture of metal gas

The same metal gases as those of Examples and Comparative Examples were used. This metal gas was produced as follows. That is, a copper alloy having a composition of Cu-25 mass% Zn-6 mass% Al-3 mass% Fe-3 mass% Mn was melted and cast into a cylindrical body having an inner diameter of 20 mm, an outer diameter of 28 mm and a width of 20 mm. Then, a plurality of cylindrical holes penetrating the outer peripheral surface and the inner peripheral surface of the cylindrical body were formed. The diameter of the hole was 4 mm, and the opening area ratio of the plurality of holes in the inner circumferential surface serving as the sliding surface of the metal base was 25%.

Manufacture of lubricating plugs

The lubrication plugs of Examples and Comparative Examples were injection-molded from raw materials having the compositions shown in Table 1 to obtain cylindrical shapes having a diameter of 4 mm and a length of 4 mm. As the polyethylene resin, LUBMER (registered trademark) (molecular weight: 500,000) manufactured by Mitsui Chemicals, Inc. was used.

The lubricating plug of Example 3 contained 1% by volume of carbon black as a coloring agent. Carbon black was manufactured by Mitsubishi Chemical Corporation under the trade name RCF # 44. The structure of the lubricating plug of Comparative Example 3 was made up of the polyethylene resin phase, the porous polyamide resin phase, and the lubricant contained in the porous polyamide phase coalescence.

Lubrication plug composition Presence of damage Example 1 Polyethylene radish Example 2 Polyethylene-20 vol% phenol radish Example 3 Polyethylene - 1 vol% Carbon black radish Comparative Example 1 Polyethylene-25vol% Paraffin-25vol% Graphite U Comparative Example 2 Polyethylene-25vol% paraffin-25vol% melamine cyanurate U Comparative Example 3 Polyethylene-45vol% Polyamide-5vol% Lubricant U Comparative Example 4 Polyethylene-25vol% phenol U

The prepared lubrication plug was embedded in the hole of the metal base and the inner peripheral surface of the metal base to be the sliding surface was polished so that the inner peripheral surface of the metal base and the surface of the lubrication plug were flush with each other, Sliding members of Examples 1 to 4 were obtained.

evaluation

Sliding tests of the sliding members of Examples 1 to 3 and Comparative Examples 1 to 4 under the conditions shown in Table 2 were performed to evaluate whether or not the surface of the lubricating plug on the sliding surface was damaged.

Specifically, the sliding surfaces of the sliding members of the examples and comparative examples tested under the conditions shown in Table 2 were measured with a shape measuring machine (roughness tester) When the step (radial step of the sliding member) was confirmed, it was determined that the surface of the lubricating plug 2 was damaged. The results are shown in the column of " Damage " in Table 1.

Testing machine Shaking Bearing Tester Surface pressure 24.5 MPa Swing angle ± 45 ° C Bending cycle 33 cpm Number of cycles 35000 Environment Underwater Relative material Stainless Steel Relative roughness 1 m (Rmax)

In the sliding members of Embodiments 1 to 3, no step is formed between the front surface of the lubricating plug and the sliding surface of the metal base. The surface of the lubricating plug maintained a smooth surface although the traces of friction with the counter material were confirmed.

It was confirmed that the sliding members of Comparative Examples 1 to 4 were all damaged in the surface of the lubricating plug and had irregular irregularities on their surfaces and sheared from the inside of the vicinity of the surface of the lubricating plug.

The lubricating plug of Comparative Example 1 includes graphite having wall characteristics, and the lubricating plug of Comparative Example 2 includes melamine cyanurate having wall characteristics. The lubricating plug of Comparative Example 3 includes lubricating oil and includes a hollow portion for containing the lubricating oil. For this reason, it is considered that shear occurred inside the vicinity of the surfaces of the lubricating plugs of Comparative Examples 1 to 3 at the time of sliding as described above as a problem of the prior art.

The lubricating plugs of Example 2 and Comparative Example 4 are made of a polyethylene resin and a phenol resin, and the structure is a mixed structure of a polyethylene phase and a phenol resin phase.

When the temperature of the lubricating plug rises, a slight shear stress is generated due to the difference in thermal expansion at the interface between the phenol resin phase and the polyethylene phase. As in Comparative Example 4, when the content of the phenolic resin is increased, the shear stress inside the lubricating plug becomes too high, and it is considered that the lubricating plug is damaged by the external force applied by sliding with the relative shaft.

The amount of the phenol resin contained in the lubricating plug should be 20% by volume or less in the same manner as in Example 4 in order to reduce the influence of the shear stress due to the difference in thermal expansion coefficient between the polyethylene resin and the phenol resin.

In Example 4, a phenol resin was added as a selective component to the polyethylene resin. However, it is also possible to use a polyamide, polyimide, polyamideimide, polytetrafluoroethylene, polyphenylene sulfide, Polyoxybenzoyl was added, it was confirmed in the sliding test that the surface of the lubricating plug was not damaged as in Comparative Example 4 when the addition amount of the optional component was 20% by volume or less.

1: underwater sliding member
2: metal gas
3: hole
3 ': concave portion
4: Lubrication plug
5: Sliding face

Claims (6)

An underwater sliding member comprising a metal base having a sliding surface and a lubricating plug,
Wherein the metal base is provided with a plurality of holes or recesses that open on the sliding surface, the lubrication plug is embedded in the hole or recess,
Wherein the lubricating plug is made of polyethylene. The method according to claim 1,
Wherein the polyethylene has a molecular weight of 200,000 or more. The method according to claim 1,
Characterized in that the lubricating plug further contains at least 20 vol% of at least one resin selected from phenol, polyamide, polyimide, polyamideimide, polytetrafluoroethylene, polyphenylene sulfide and polyoxybenzoyl Underwater sliding member. 4. The method according to any one of claims 1 to 3,
Wherein the lubricating plug further contains a coloring agent of not more than 1% by volume. The method according to claim 1,
Wherein the base has a cylindrical shape whose inner peripheral surface is the sliding surface. The method according to claim 1,
Wherein the base is in the form of a flat plate.

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