JP2018071581A - Slide device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slide device in which a shaft member having a slide surface made of resin composition and a slide member having a slide surface made of resin composition are combined to each other that shows a superior abrasion resistance at a slide layer even under non-lubrication condition and shows a fast stable state in its slide performance.SOLUTION: A shaft member has hard particles of 5 to 50 vol.% dispersed in synthetic resin, a slide member includes a rear alloy layer and a slide layer, a slide layer has graphite particles of 5 to 50 vol.% and PTFE particles of 0.2 vol.% to 1 vol.% or less dispersed in the synthetic resin. Graphite particles are composed of long spheroidal graphite particles and scaly graphite particles, a volumetric rate of the scaly graphite particles in respect to the entire graphite particles is 10 to 40 vol.%. A cross section texture of long spheroidal graphite particles shows that several AB planes of graphite crystals are laminated in a curved line shape along a round shape of the particle surfaces from the particle surface toward the central direction and the scaly graphite particles show that several AB planes are laminated in a thickness direction of thin plate shape. Average particle diameter of the long spheroidal graphite particles is 3 to 50 μm, average particle diameter of the scaly graphite particles is 1 to 25 μm and average particle diameter of PTTFE particles is 1 to 25 μm, respectively.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sliding device. Specifically, a shaft member made of synthetic resin, and a sliding member that includes a sliding layer made of synthetic resin and graphite on a back metal layer and supports the shaft member. The present invention relates to a sliding device.

  A sliding device having a structure in which two sliding members whose sliding surfaces that are in sliding contact with each other are resin compositions is combined is used. Of the two sliding members, one is a shaft member that performs a rotating operation or a reciprocating operation, and the other is a sliding member having a sliding layer that supports the shaft member. As the shaft member, one in which hard particles such as carbon fiber, glass fiber, metal particle, ceramic particle and the like are contained in a synthetic resin in order to increase the strength is conventionally known (Patent Document 1, Patent Document 2). reference).

  On the other hand, as a sliding member, what has the resin composition which added scaly graphite as a solid lubricant to a synthetic resin is used conventionally (patent document 3). Natural graphite is generally classified into scaly graphite, scaly graphite, and soil graphite depending on its properties. The degree of graphitization is the highest at 100% for scaly graphite, then 99.9% for scaly graphite, and 28% for soil graphite. Conventionally, as a solid lubricant for a sliding member, scaly graphite having a high degree of graphitization or scaly particles obtained by mechanically grinding natural graphite of scaly graphite has been used.

  This scaly graphite is a crystal in which carbon atoms regularly form a network structure and a large number of AB planes (hexagonal plane planes, basal planes) spread in a plane and have a thickness in the C-axis direction perpendicular to the AB plane. It is. Since the bonding force due to the van der Waals force between the laminated AB surfaces is much smaller than the bonding force in the in-plane direction of the AB surface, shearing is likely to occur between the AB surfaces. Therefore, this graphite has a thin plate shape as a whole because the thickness of the laminated layer is small with respect to the spread of the AB surface. In addition, it is thought that scaly graphite particles function as a solid lubricant by shearing between AB surfaces when receiving external force.

In recent years, in a sliding member using a resin composition containing scaly graphite particles, the surface of the resin composition serving as a sliding surface is machined because the shape of the scaly graphite particles is thin and brittle. When processed, the flaky graphite particles break and fall off, resulting in a problem that the surface roughness of the sliding layer is deteriorated, and as a result, seizure resistance is deteriorated. In order to solve this problem, for example, Patent Document 4 proposes a sliding material capable of containing spherical natural graphite particles in a synthetic resin and reducing the surface roughness after machining.
Here, the spheroidized graphite particles are obtained by using natural scale-like graphite particles as a raw material, repeatedly applying a small load to the scale-like graphite particles, and bending the particles into a spherical shape (Patent Documents 5 and 6). reference).

JP 2001-132757 A JP-A-5-179277 JP 2005-89514 A International Publication No. 201204107 International Publication No. 2012/137770 JP 2008-24588 A

  A sliding device having a structure in which a sliding member that slides relative to each other is made of a resin composition and a sliding member has a structure in which oil is not supplied between the sliding surfaces (hereinafter referred to as “non-lubricated”). In many cases, the operation is performed under the “condition”, and the sliding surface of the sliding member and the surface of the shaft member are in direct contact with each other under the non-lubricated condition. A sliding member using a resin composition in which natural graphite spheroidized graphite particles are contained in a synthetic resin as in Patent Document 4 supports a shaft member made of a resin composition containing hard particles under non-lubricating conditions. When used in sliding parts, the surface of the sliding layer of the sliding member is scratched and wear easily occurs. It has been found that the amount of wear of the sliding layer increases as a result of falling off.

  Also, in a sliding device having a structure in which a sliding member is a combination of a shaft member and a sliding member whose both sliding surfaces are resin compositions, the friction coefficient usually starts to increase after the sliding starts, for a certain period of time. Among them, the friction coefficient is stabilized at a constant value. However, in the sliding member using the resin layer in which the scaly graphite particles are contained in the synthetic resin as in Patent Document 3, the scaly graphite particles fall off from the sliding surface during sliding, and the resin composition. If the graphite particles are excessively transferred to the surface of the shaft member as described above, the time from the start of sliding until the coefficient of friction becomes stable It has been found that it becomes longer than usual, that is, the sliding performance is not stable.

  Accordingly, an object of the present invention is to overcome the above-mentioned drawbacks of the prior art in a sliding device having a structure in which a shaft member and a sliding member whose sliding surfaces are both resin compositions are combined. It is an object of the present invention to provide a sliding device that is excellent in wear resistance of a sliding layer of a moving member and that has stable sliding performance at an early stage.

According to one aspect of the present invention, there is provided a sliding device including a shaft member made of a synthetic resin in which 5 to 50% by volume of hard particles are dispersed, and a sliding member that supports (supports) the shaft member. The
The sliding member includes a backing metal layer and a sliding layer provided on the backing metal layer. The sliding layer comprises a synthetic resin, graphite particles dispersed in the synthetic resin, and PTFE (polytetrafluorocarbon). Ethylene) particles. The graphite particles occupy 5 to 50% by volume of the sliding layer, and the PTFE particles occupy 0.2% by volume or more and less than 1% by volume of the sliding layer. The graphite particles are composed of long spherical graphite particles and thin scaly graphite particles, and the ratio of the volume of the scaly graphite particles to the total volume of the graphite particles is 10 to 40%. As for the cross-sectional structure of the long spherical graphite particles, a plurality of AB planes of the graphite crystal are laminated in a curved shape along the roundness of the particle surface from the particle surface toward the center. As for the cross-sectional structure of the scaly graphite particles, the AB surface of the graphite crystal is laminated in the thickness direction of the thin plate shape (C-axis direction perpendicular to the AB surface of the graphite crystal). The average particle diameter of the long spherical graphite particles is 3 to 50 μm, and the average particle diameter of the scaly graphite particles is 1 to 25 μm. The average particle diameter of the PTFE particles is 1 to 25 μm.

In the sliding device of the present invention, the oblong graphite particles dispersed in the sliding layer of the sliding member mainly act as a lubricating component.
The cross-sectional (internal) structure of the oblong graphite particles dispersed in the sliding layer has a plurality of curved shapes along the roundness of the particle surface with the AB surface (hexagonal network surface plane) of the graphite crystal from the particle surface toward the center. Because of the lamination, the surface of the oblong graphite particles exposed on the sliding surface of the sliding layer is composed of the AB surface of graphite crystals.
As described above, the graphite crystal is a crystal in which a large number of AB planes are laminated and has a thickness in the C-axis direction perpendicular to the AB plane, and the bonding force (van der Waals force) between the laminated AB planes is: Since the bonding force in the in-plane direction of the AB surface is much smaller, shearing is likely to occur between the AB surfaces. When the surface consisting of the AB surface of the graphite crystal is exposed on the sliding surface, the AB surface contacts the surface of the shaft member on the sliding surface, so even if the load from the shaft member is small, shearing is performed between the AB surfaces. As a result, the frictional force between the sliding surface and the surface of the shaft member is reduced, and the wear amount of the sliding layer is reduced.

  Further, the sliding member of the sliding device of the present invention can prevent the surface of the sliding member from being scratched mainly by the action of the scaly graphite particles dispersed in the sliding layer of the sliding member. It is.

  The scaly graphite particles exposed to the sliding surface of the sliding member due to sliding with the shaft member wear away from the sliding surface and fall off, but the scaly graphite particles are thin, so the sliding surface and shaft It penetrates into the gap between the surface of the member. The scaly graphite particles that have entered the gap are transferred to the shaft member such that the flat plate surface (AB surface) of the scaly graphite particles is parallel to the surface of the shaft member. The transferred scaly graphite particles slightly protrude toward the sliding surface of the sliding member with respect to the surface of the shaft member. Many such transfer parts are formed on the surface of the shaft member. Since the transfer part of the scaly graphite particles on the surface of the shaft member is in contact with the sliding surface of the sliding member, the hard particles exposed on the surface of the original shaft member are exposed on the sliding surface of the sliding member. Direct contact with the graphite particles is prevented or the frequency of contact is reduced. As a result, the occurrence of scratches on the sliding surface of the sliding member is suppressed.

  In a sliding device using a conventional sliding member having a sliding layer made of synthetic resin and spherical graphite particles, the sliding member is likely to be worn. This is because the hard particles exposed on the surface of the shaft member and the sliding surface of the sliding member slide in direct contact with each other, so that the sliding surface of the sliding member is damaged and the sliding layer wears. It is because it becomes easy to occur.

  The average particle size of the long spherical graphite particles is preferably 3 to 50 μm. The oval graphite particles exposed on the sliding surface support the load from the surface of the shaft member, but if the average particle size is less than 3 μm, a part of the oval graphite particles exposed on the sliding surface when sliding May easily fall off the sliding surface, and the ability of the sliding layer to support the load may be reduced. If the average particle diameter of the long spherical graphite particles exceeds 50 μm, scratches may occur on the surface of the sliding layer.

  The average particle size of the scaly graphite particles is preferably 1 to 25 μm. When the average particle size of the flaky graphite particles is less than 1 μm, aggregated portions of the flaky graphite particles are easily formed in the sliding layer, and the strength of the sliding layer may be reduced. If the average particle size of the scaly graphite particles exceeds 25 μm, the scaly graphite particles in the sliding layer may be sheared by a load applied to the sliding layer during sliding, and the strength of the sliding layer may be reduced.

  As described above, the scaly graphite particles exposed on the sliding surface of the sliding member are transferred to the surface of the shaft member by sliding with the shaft member, but the scaly graphite particles are excessively transferred to the surface of the shaft member. When worn, it has been found that the time from the start of sliding to the stabilization of the friction coefficient becomes longer, that is, the time until the friction coefficient starts to increase and becomes constant becomes longer.

The sliding layer of the sliding member of the present invention contains PTFE particles in an amount of 0.2% by volume or more and less than 1% by volume with respect to the volume of the sliding layer. Excessive transfer is prevented. If the transfer part of the scaly graphite particles is excessively formed on the shaft member, the scaly graphite transferred by the load applied during sliding is easily sheared and falls off, and the scaly graphite on the surface of the shaft member occurs. The friction coefficient becomes difficult to be stabilized by repeating the formation and dropping of the transfer part of the particles.
In the present invention, PTFE has high adhesiveness to the mating material, and therefore, PTFE particle wear powder exposed on the surface of the sliding layer is first transferred to the shaft member due to the load applied to the sliding layer at the start of sliding. Then, a transfer film is formed. Thereafter, the scaly graphite particles gradually move to the shaft member. However, since a fixed PTFE transfer film is already formed on the shaft member in the initial stage of sliding, the scaly graphite particles are excessively applied to the shaft member. It is considered that the transfer is suppressed, so that the friction coefficient is stabilized in a short time. If the PTFE particles contained in the sliding layer are less than 0.2% by volume, the transfer film of PTFE on the surface of the shaft member at the initial stage of sliding becomes insufficient, and the scaly graphite particles are transferred to the shaft member. In some cases, the time until the friction coefficient is stabilized due to the difficulty of suppressing the adhesion is increased. On the other hand, if the PTFE particles contained in the sliding layer is 1% by volume or more, a transfer film of excessive PTFE particles is formed at the initial stage of sliding, so that the time until the friction coefficient continues to decrease and stabilizes. May be longer.

  The average particle size of the PTFE particles is preferably 1 to 25 μm. If the average particle size of the PTFE particles is less than 1 μm, a part of the PTFE particles exposed to the sliding surface during sliding is likely to drop off from the sliding surface before the transfer film is formed. Since the PTFE particles dropped from between the sliding surface and the surface of the shaft member are discharged, the formation of the transfer film of the PTFE particles may be insufficient. If the average particle diameter of the PTFE particles exceeds 25 μm, the PTFE particles in the sliding layer may be sheared by a load applied to the sliding layer during sliding, and the strength of the sliding layer may be reduced.

  According to one embodiment of the present invention, the average aspect ratio A1 of the PTFE particles is preferably 1.5 to 4.5. The average aspect ratio of PTFE particles is represented by the average of the ratio of the major axis to the minor axis of PTFE particles. When the average aspect ratio A1 of the PTFE particles is 1.5 or more, a transfer film is more easily formed on the surface of the shaft member than when the average aspect ratio A1 is less than 1.5. This is presumably because the PTFE particles have a large surface area, so that the adhesion with the synthetic resin is increased, so that the PTFE particles do not easily fall off the sliding surface during sliding. Further, the average aspect ratio A1 of the PTFE particles is preferably 2 or more. Further, when the average aspect ratio A1 of the PTFE particles is 4.5 or less, the strength of the sliding layer becomes larger than when the average aspect ratio exceeds 4.5. This is because shearing does not easily occur in the PTFE particles exposed on the sliding surface due to a load during sliding. If the particles have the same volume, the larger the aspect ratio, the larger the area exposed on the sliding surface, and shearing tends to occur.

  According to one embodiment of the present invention, the average aspect ratio A2 of the oblong graphite particles is preferably 1.5 to 4.5. The average aspect ratio of the long spherical graphite particles is represented by the average ratio of the long axis and the short axis of the long spherical graphite particles. When the average aspect ratio A2 of the long spherical graphite particles is 1.5 or more, the wear resistance is further improved as compared with the case where the average aspect ratio A2 is less than 1.5. This is because the contact area of the oblong graphite particles with the synthetic resin is increased by increasing the surface area of the oblong graphite particles, and the adhesion with the synthetic resin is increased. This is thought to be difficult. Furthermore, the average aspect ratio A2 of the long spherical graphite particles is preferably 2 or more.

The spheroidized graphite particles, which are raw materials for the long spherical graphite particles, are granulated in a spherical shape by repeatedly applying a small load to natural scaly graphite particles and bending them. When a large load is applied to natural scaly graphite particles during granulation, shearing occurs between the AB surfaces and the particles are crushed into small scaly shapes, so the applied load must be reduced. For this reason, in the inside of the spheroidized particles, there is a portion where the contact between the surfaces of the scaly graphite particles before granulation is insufficient, and voids are easily formed between the surfaces of the scaly graphite particles (see Patent Document 5). FIG. 5C and FIG. 3 to FIG. 6 of Patent Document 6).
When the spherical natural graphite particles are dispersed in the synthetic resin of the sliding member while maintaining the spherical shape, there are voids in the graphite particles, so the graphite particles exposed on the sliding surface are loaded. When it receives, there is a problem that the graphite particles are cracked, fall off from the sliding surface, enter the gap between the shaft member surface and damage the sliding surface of the sliding member and the shaft member surface.

  The long spherical graphite particles having the above average aspect ratio A2 of the present invention are formed by a process of imparting a long spherical shape to the raw spherical graphite particles as will be described later. The voids inside can be eliminated. When the average aspect ratio A2 of the long spherical graphite particles is 1.5, there are less voids in the cross-sectional structure of the long spherical graphite particles, and when the average aspect ratio A2 is 2 or more, the cross-sectional structure of the long spherical graphite particles No voids are present in the glass, and even if the oblong graphite particles exposed on the sliding surface are subjected to a load from the counterpart shaft, the oblong graphite particles are not cracked. Therefore, the oblong graphite particles fall off from the sliding surface, or fragments are generated due to cracking of the oblong graphite particles and enter the gap between the shaft member surface and the sliding surface of the sliding member. The problem of damage to the surface of the shaft member does not occur.

According to one embodiment of the present invention, the scaly graphite particles have an average aspect ratio A3 of 5-10. The average aspect ratio of the scaly graphite particles is represented by the average ratio of the major axis to the minor axis of the scaly graphite particles.
Further, the scaly graphite particles preferably have an anisotropic dispersion index S of 3 or more. This anisotropic dispersion index S is defined as the average of the values of the ratio X1 / Y1 for each scaly graphite particle. Here, X1 is the length parallel to the sliding surface of the scaly graphite particles in the cross-sectional structure perpendicular to the sliding surface of the sliding layer, and Y1 is the sliding surface of the sliding layer. On the other hand, it is the length in the direction perpendicular to the sliding surface of the scaly graphite particles in the cross-sectional structure in the vertical direction.

  The value of the anisotropic dispersion index S increases as the ratio of the flat surface of the scaly graphite particles in the sliding layer (in which the AB surface spreads) is oriented substantially parallel to the sliding surface increases. As described above, the scaly graphite particles exposed on the sliding surface of the sliding member fall off from the sliding surface by sliding between the sliding member and the shaft member of the sliding device. The scaly graphite particles have a thin plate shape with an average aspect ratio A3 of 5 to 10 as described above, and further, since the anisotropic dispersion index S is 3 or more, the flat plate surface is oriented substantially parallel to the sliding surface. The ratio of things is large. Therefore, immediately after falling off, the scaly graphite particles have a flat surface substantially parallel to the surface of the shaft member, and are easily transferred to the surface of the shaft member. The anisotropic dispersion index S of the scaly graphite particles is more preferably 4 or more.

  According to one embodiment of the present invention, the synthetic resin used for the sliding layer of the sliding member is PAI (polyamideimide), PI (polyimide), PBI (polybenzimidazole), PA (polyamide), phenol, epoxy. , POM (polyacetal), PEEK (polyetheretherketone), PE (polyethylene), PPS (polyphenylene sulfide), and PEI (polyetherimide).

According to an embodiment of the present invention, the sliding layer of the sliding member further includes 1 to 20% by volume of one or more solid lubricants selected from MoS ₂ , WS ₂ , and h-BN. be able to. By containing this solid lubricant, the sliding characteristics of the sliding layer can be enhanced.

According to one embodiment of the present invention, the sliding layer of the sliding member is selected from CaF ₂ , CaCo ₃ , talc, mica, mullite, iron oxide, calcium phosphate and Mo ₂ C (molybdenum carbide). The seed or two or more fillers may further comprise 1 to 10% by volume. By containing this filler, the wear resistance of the sliding layer can be increased.

According to one embodiment of the present invention, the sliding member may further include a porous metal layer between the back metal layer and the sliding layer. By providing the porous metal layer on the surface of the back metal layer, the bonding strength between the sliding layer and the back metal layer can be increased. That is, the bonding force between the backing metal layer and the sliding layer can be enhanced by the anchor effect by impregnating the pores of the porous metal layer with the composition constituting the sliding layer.
The porous metal layer can be formed by sintering metal powder such as Cu, Cu alloy, Fe, Fe alloy or the like on the surface of a metal plate or strip. The porosity of the porous metal layer may be about 20 to 60%. The thickness of the porous metal layer may be about 0.05 to 0.5 mm. In this case, the thickness of the sliding layer coated on the surface of the porous metal layer may be about 0.05 to 0.4 mm. However, the dimension described here is an example, and the present invention is not limited to this value, and can be changed to a different dimension.

  According to one specific example of the present invention, the synthetic resin used for the shaft member is PAI (polyamideimide), PI (polyimide), PBI (polybenzimidazole), PA (polyamide), PF (phenol), EP (epoxy). ), POM (polyacetal), PEEK (polyetheretherketone), PE (polyethylene), PPS (polyphenylenesulfide) and PEI (polyetherimide).

According to one embodiment of the present invention, the hard particles used for the shaft member are CF (carbon fiber), GF (glass fiber), BN, Al ₂ O ₃ , SiC, SiO ₂ , AlN, and TiO ₂ . It can consist of 1 type, or 2 or more types chosen from. When the shaft member contains these hard particles, the strength (rigidity) of the shaft member is increased. The average particle diameter of the hard particles can be 1 to 50 μm.

The shaft _member, CaF 2, CaCo _3, talcum, mica, mullite, iron oxide, calcium phosphate and _Mo 2 C 1 kind selected from among (molybdenum carbide) or two or more fillers 1-10% by volume Can further be included. Further, the shaft member can further include one or more solid lubricants selected from MoS ₂ , WS ₂ , h-BN and PTFE and / or 5% by volume or less of oil.

The figure which shows the sliding apparatus by an example of this invention. The figure which shows the cross section of the sliding member by an example of this invention. The figure which shows the cross section of the shaft member by an example of this invention. The figure explaining the aspect ratio (A1) of PTFE oblong graphite particles. The figure explaining the aspect ratio (A2) of an oblong graphite particle. The figure explaining the aspect ratio (A3) and anisotropic dispersion index (S) of scaly graphite particles. The figure which shows the cross section of the sliding member by the other example of this invention. The figure which shows the example of 1 specific form of the sliding apparatus of this invention.

FIG. 1 schematically shows an example of a sliding device 1 according to the present invention. The sliding device 1 includes a shaft member 2 and a sliding member 3 that supports the shaft member 2. The sliding member 3 has a backing metal layer 4 and a sliding layer 5.
As a specific form of the sliding device 1 of the present invention, a cylindrical shaft member 2 can be a sliding device supported by a cylindrical sliding member 3 (see FIG. 8). In this case, the sliding layer 5 is formed on the inner surface of the cylindrical sliding member 3. However, the sliding device according to the present invention is not limited to this form, and the shaft member 2 and the sliding member 3 may be flat or any other form.

FIG. 2 schematically shows a cross section of an example of the sliding member 3 of the sliding device according to the present invention. The sliding member 3 is provided with a sliding layer 5 on a back metal layer 4. In the sliding layer 5, 5 to 50% by volume of graphite particles 7 and 0.2% by volume or more and less than 1% by volume of PTFE particles 11 are dispersed in the synthetic resin 6. The graphite particles 7 are composed of long spherical graphite particles 71 and flaky graphite particles 72. The volume ratio of the scaly graphite particles 72 to the total volume of the graphite particles 7 is 10 to 40%. The cross-sectional (internal) structure of the oblong graphite particles 71 is such that the AB surface of the graphite crystal is laminated in a curved shape along the roundness of the particle surface from the particle surface toward the center. There are no voids in the tissue. As for the cross-sectional structure of the scaly graphite particles 72, a plurality of the AB surfaces of the graphite crystals are laminated in the thickness direction of the thin plate (the C-axis direction perpendicular to the AB surface of the graphite crystals). The average particle diameter D1 of the PTFE particles 11 is 1 to 25 μm, the average particle diameter D2 of the long spherical graphite particles is 3 to 50 μm, and the average particle diameter D3 of the scaly graphite particles is 1 to 25 μm.
A porous metal layer 8 may be provided between the sliding layer 5 and the back metal layer 4. FIG. 7 schematically shows a cross section of an example of the sliding member provided with the porous metal layer 8.

As used herein, the term “oval” does not mean a geometrically exact oval, but in a broad sense extends long in one direction (ie has the following aspect ratio) and has a corner. This means that it does not have an irregular shape.
Further, the absence of voids in the structure of the long spherical graphite particles 71 means that a plurality of (for example, 20) graphite particles are magnified using an electron microscope in a cross section perpendicular to the sliding surface of the sliding layer 5. This can be confirmed by taking an electronic image at 2000 times and observing that no voids are formed in the cross-sectional structure of the particles of the long spherical graphite 71 in the taken image. However, although the formation of fine-line voids having a width of 0.1 μm or less is allowed in the cross-sectional structure of the long spherical graphite particles 71, the total area of the fine-line voids having a width of 0.1 μm or less is long. The area ratio in the cross-sectional structure of the spherical graphite particles 71 is limited to 3% or less.

  The average aspect ratio A1 represented by the average ratio of the major axis to the minor axis of the PTFE particles 11 dispersed in the sliding layer 5 is preferably 1.5 to 4.5, and preferably 2 or more. More preferred.

The average aspect ratio A2 represented by the average ratio of the major axis to the minor axis of the long spherical graphite particles 71 dispersed in the sliding layer 5 is preferably 1.5 to 4.5.
On the other hand, the average aspect ratio A3 represented by the average ratio of the major axis to the minor axis of the scaly graphite particles 72 is preferably 5 to 10.

  Furthermore, it is preferable that the scale-like graphite particles 72 have an anisotropic dispersion index S of 3 or more. The anisotropic dispersion index S is X1 as the length in the direction parallel to the sliding surface of the scaly graphite particles 72 in the cross-sectional structure perpendicular to the sliding surface of the sliding layer, and the sliding of the sliding layer. When the length in the direction perpendicular to the sliding surface of the scaly graphite particles 72 in the cross-sectional structure perpendicular to the surface is Y1 (see FIG. 6), the ratio X1 / Y1 of each scaly graphite particle Values are expressed as averages for all scaly graphite particles. Furthermore, the anisotropic dispersion index S is preferably 4 or more.

The sliding member of the above-described sliding device will be described in detail below along the manufacturing process.
(1) Preparation of raw material graphite particles Spherical graphite particles obtained by granulating scaly natural graphite can be used as raw materials for the long spherical graphite particles. The spherical graphite particles have a structure in which a plurality of graphite crystal AB planes are laminated in a curved shape along the roundness of the particle surface from the particle surface to the inside, and voids are formed inside the particles. . As the spherical graphite particles as the raw material, those having an average particle diameter of 2 to 60 μm and a circularity of 0.92 or more as measured by a laser diffraction particle size measuring device are preferably used. Here, the circularity is expressed by the following equation.
Circularity = (perimeter of a circle having the same area as the projected particle shape) / (perimeter of the projected particle shape)
When the projected particle shape forms a perfect circle, the circularity is 1. The projected particle shape can be obtained from a photographed image obtained using an optical microscope or a scanning electron microscope.
When the raw material spherical graphite particles having a circularity of less than 0.92 are used, the surface of the graphite particles tends to be unevenly loaded during the process of eliminating voids in the mixing step described later. The surface of the particle is locally deformed and sheared, or cracks are generated inside and new voids are easily formed.

  As a raw material of the scaly graphite particles, natural scaly graphite particles having a thin plate shape are used. The scaly graphite particles have an average particle size in the direction parallel to the AB surface measured by a laser diffraction particle size measuring device of 1 to 30 μm and an average particle thickness of 0.2 to 3.5 μm. It is preferable to use particles.

(2) Preparation of raw material PTFE particles As the raw material of the PTFE particles, it is preferable to use oval PTFE particles having an average particle diameter measured by a laser diffraction particle size measuring apparatus of 2 to 30 μm.

(3) Preparation of synthetic resin particle It is preferable to use what has an average particle diameter of 50 to 150% of the average particle diameter of a spherical graphite particle as the synthetic resin particle which is a raw material. As synthetic resin, what consists of 1 type (s) or 2 or more types chosen from PAI, PI, PBI, PA, a phenol, an epoxy, POM, PEEK, PE, PPS, and PEI can be used.

(4) Mixing Spherical graphite particles and scaly graphite particles are adjusted so that the volume ratio of the scaly graphite particles is 10 to 40% of the total graphite particle volume. Next, the spherical graphite particles and the scaly graphite particles, the PTFE particles, and the synthetic resin particles so that the graphite component is 5 to 50% by volume and the PTFE component is 0.2 to 1% by volume. Adjust the percentage. The spherical graphite particles, scaly graphite particles, PTFE particles, and synthetic resin particles are diluted with an organic solvent to prepare a composition having a viscosity of 40,000 to 110,000 mPa · s. By mixing this diluted solution with a roll mill, a long spherical shape is imparted to the spherical graphite particles that are substantially spherical during mixing, and at the same time, voids in the internal structure of the spherical graphite particles are reduced or eliminated.

The reason is considered as follows.
The viscosity of the diluted liquid of the resin composition containing conventional graphite particles and other filler particles is usually about 15000 mPa · s at the maximum. However, here, the viscosity of the diluted composition is set to 40,000 to 110,000 mPa · s, which is larger than usual. This increases the frequency with which the spherical graphite particles and the resin particles simultaneously pass through the gap (gap) between the rolls of the roll mill during mixing by the roll mill. When the spherical graphite particles and the resin particles pass through the roll gap at the same time, the graphite particles are deformed by applying a load to the spherical graphite particles. By being relaxed by the deformation of the particles, it is possible to prevent an excessive load from being locally applied to the surface of the spherical graphite particles and to deform the graphite particles without shearing. The graphite particles are gradually deformed and given a long spherical shape every time they pass through the roll gap of the roll mill together with the synthetic resin particles, and at the same time, voids inside the particles are reduced or eliminated.
When the viscosity of the composition exceeds 110000 mPa · s, the concentration of the solvent is too low, and it becomes difficult to uniformly disperse the resin particles, the long spherical graphite particles, and the scaly graphite particles. Furthermore, cracks may occur in the scaly graphite particles during mixing with a roll mill.

  The gap between rolls of the roll mill is set to an interval corresponding to 150% to 250% of the average particle diameter of the spherical graphite particles. In the prior art, when a resin composition containing graphite particles or other filler particles that are sliding members is mixed using a roll mill, the mixing is simply performed in an organic solvent with resin particles and graphite particles or other fillers. The purpose is to uniformly disperse the particles, and the gap between rolls of the roll mill is considerably larger than the particle size of the raw material resin particles and graphite particles (for example, about 400% of the average particle size of the graphite particles). It was made to.

  Note that even if a composition obtained by diluting only spherical graphite particles with an organic solvent is passed through a roll mill, the spherical graphite particles cannot be deformed. In this case, shearing and cracking occur in the spherical graphite particles and no deformation occurs. This is because when the spherical graphite particles pass through the gap between the rolls, a large load is locally applied to the contact portions of the spherical graphite particles with the roll surface and the contact portions of the spherical graphite particles, resulting in shearing and cracking. It is done.

  The relationship that the average particle diameter of the synthetic resin particles described above is 50 to 150% of the average particle diameter of the spherical graphite particles is that an excessive load is applied to the graphite particles when passing through the gap between the rolls, and shearing occurs. It is suitable for preventing. When the sliding layer further contains a solid lubricant or filler, the solid lubricant or filler particles should have an average particle size of 50% or less of the average particle size of the spherical graphite particles. preferable.

  In the above-described mixing step, the PTFE particles maintain the grain shape at the time of the raw material.

  The method of mixing the synthetic resin particles, the spherical graphite particles and the scaly graphite particles is not limited to the mixing method using the roll mill shown in the above embodiment, but using other mixers or adjusting other mixing conditions Is also possible.

(5) Back metal As a back metal layer, metal plates, such as Fe alloy, Cu, and Cu alloy, can be used. The porous metal layer may be formed on the surface of the back metal layer, that is, the side that becomes the interface with the sliding layer, but the porous metal layer may have the same composition as the back metal layer, or a different composition or material may be used. Is possible.

(6) Coating process The composition after mixing is applied to one surface of the back metal layer or the porous metal layer on the back metal layer, and the back metal applied with the composition has a uniform thickness. And passed between rolls having a predetermined constant gap.
The viscosity of the composition after mixing is also closely related to the long-axis anisotropic (orientation) dispersion of the scaly graphite particles in the sliding layer of the sliding member, and the anisotropic dispersion of the scaly graphite particles It was found that setting conditions in this coating step is important.

When the viscosity of the composition is high in the mixing step (the ratio of the organic solvent is small), the scaly graphite particles in the composition (the flat surface of which is slid) are transferred when the back metal layer coated with the composition passes between the rolls. This is because it becomes difficult to flow (in a direction parallel to the moving surface).
On the other hand, when the viscosity of the composition is 110000 mPa · s or less, the oval graphite particles easily flow together with the organic solvent in the coating step. In the sliding layer, it is oriented, that is, anisotropically dispersed. Specifically, when the viscosity of the composition is 110000 mPa · s or less, the scale-like graphite particles dispersed in the sliding layer have an anisotropic dispersion index S of 2.5 or more. Furthermore, when the viscosity of the composition is 100,000 mPa · s or less, the anisotropic dispersion index is 3 or more, and when it is 80000 mPa · s or less, the anisotropic dispersion index is 4 or more.

(7) Drying / firing step The backing metal layer (or backing metal layer and porous porous metal layer) coated with the composition is heated to dry the organic solvent in the composition, and the resin in the composition is fired. For this reason, the sliding member is obtained. As these heating conditions, conditions generally used for the resin used can be adopted.

(8) Measurement The average particle diameter D2 of the oblong graphite particles is obtained by taking a cross section perpendicular to the sliding surface of the sliding member and taking an electron image at 200 times using an electron microscope. The diameter was measured. Specifically, the average particle diameter of the long spherical graphite particles is determined by using a general image analysis method (analysis software: Image-Pro Plus (Version 4.5); manufactured by Planetron Co., Ltd.). Then, the area of each oblong graphite particle is measured, and it is calculated by converting it into an average diameter when it is assumed to be a circle.

  The average particle diameter D3 of the scaly graphite particles is also the average when the area of each scaly graphite particle is measured using the image analysis method described above for the electronic image obtained by the above method and assumed to be a circle. Calculated in terms of diameter. However, the photographing magnification of the electronic image is not limited to 200 times, and can be changed to other magnifications.

  The average particle diameter D1 of the PTFE particles is also converted into an average diameter when the area of each PTFE particle is measured using the above-described image analysis method using the electronic image obtained by the above method and assumed to be a circle. Ask. However, the photographing magnification of the electronic image is not limited to 200 times, and can be changed to other magnifications.

  The aspect ratio A1 of the PTFE particles is obtained by converting the electronic image obtained by the above method into the ratio of the long axis length L1 and the short axis length S1 of each PTFE particle (the long axis It is obtained as an average of length L1 / short axis length S1) (see FIG. 4). The major axis length L1 of the PTFE particles indicates the length at the position where the length of the PTFE particles in the electronic image is maximum, and the minor axis length S1 of the PTFE particles is the length of the major axis. The length at the position where the length in the direction orthogonal to the direction of the length L1 is maximum is shown.

  The aspect ratio A2 of the long spherical graphite particles is obtained by using the above-described image analysis method and the ratio of the long axis length L2 to the short axis length S2 of each long spherical graphite particle. It is obtained as an average of (long axis length L2 / short axis length S2) (see FIG. 5). The long axis length L2 of the long spherical graphite particles indicates the length at the position where the length of the long spherical graphite particles in the electron image is maximum, and the short axis length S2 of the long spherical graphite particles. Indicates the length at the position where the length in the direction orthogonal to the direction of the length L2 of the long axis is maximum.

  The aspect ratio A3 of the scaly graphite particles is the ratio of the major axis length L3 and the minor axis length S3 of each scaly graphite particle using the above-described image analysis technique based on the electronic image obtained by the above technique. Obtained as an average of (long axis length L3 / short axis length S3) (see FIG. 6). Note that the length L3 of the long axis of the scaly graphite particles indicates the length at the position where the length of the scaly graphite particles in the electronic image is maximum, and the length S3 of the short axis of the scaly graphite particles. Indicates the length at the position where the length in the direction orthogonal to the direction of the length L3 of the long axis is maximum.

The long spherical graphite particles have a cross-sectional structure in which the AB surface of the graphite crystal is laminated in a curved shape along the roundness of the particle surface from the particle surface toward the center. In a cross section perpendicular to the sliding surface, an electron image of a plurality (for example, 20) of long spherical graphite particles was photographed at a magnification of 2000 using an electron microscope, and the cross-sectional structure of the long spherical graphite particles in the photographed image However, it was confirmed by observing that a layered portion was formed along the roundness of the particle surface from the particle surface toward the center.
Even if spheroidized natural graphite particles are used as a raw material and the graphite particles are subjected to a treatment for eliminating voids in the internal structure of the graphite particles in the mixing step, a part of the long spherical graphite particles is obtained by the above observation method. Inside, fine line voids having a width (width in the direction perpendicular to the AB surface of the graphite crystal in the structure) of 0.1 μm or less, the total area of the voids is 3 in terms of the area ratio in the cross-sectional structure of the oblong graphite particles. However, the long spherical graphite particles having such fine-line voids have the same sliding performance as the long spherical graphite particles having no voids.

  The scaly graphite particles have a cross-sectional structure in which the AB surface of the graphite crystal is laminated in the thickness direction of the thin plate shape (C-axis direction perpendicular to the AB surface of the graphite crystal). That is, in a cross section perpendicular to the sliding surface of the sliding member, an electronic image of a plurality (for example, 20 pieces) of scaly graphite particles is taken at a magnification of 2000 using an electron microscope, and the scales in the photographed image are taken. It was confirmed by observing that the cross-sectional structure of the glassy graphite particles was formed as a layered portion in which a plurality of laminated layers were formed in the thickness direction of the thin plate shape.

  The anisotropic dispersion index S of the scaly graphite particles 72 is obtained by using the above image analysis method for an image obtained by photographing an electronic image at a magnification of 200 using an electron microscope with respect to a cross section perpendicular to the sliding surface of the sliding member. The length X1 in the direction parallel to the sliding surface of each scaly graphite particle 72 in the sliding layer and the length Y1 in the direction perpendicular to the sliding surface are measured, and the ratio X1 of these lengths The average value of / Y1 was calculated (see FIG. 6).

  FIG. 3 schematically shows a cross section of an example of the shaft member 2 of the sliding device 1 according to the present invention. In the shaft member 2, hard particles 10 are dispersed in a synthetic resin 9. The manufacturing process of a shaft member can be formed into a predetermined shape such as a columnar shape or a flat plate shape by injection molding by mixing synthetic resin and hard particles and then pelletizing.

  The synthetic resin 9 of the shaft member 2 is PAI (polyamideimide), PI (polyimide), PBI (polybenzimidazole), PA (polyamide), PF (phenol), EP (epoxy), POM (polyacetal), PEEK (poly). It can be composed of one or more selected from ether ether ketone), PE (polyethylene), PPS (polyphenylene sulfide), and PEI (polyetherimide).

The shaft member 2 includes a synthetic resin 9 and hard particles 10 dispersed in the synthetic resin 9, and the hard particles 10 can occupy 5 to 50% by volume of the sliding layer 5.
The hard particles 10 of the shaft member 2 include one or more selected from CF (carbon fiber), GF (glass fiber), BN, Al ₂ O ₃ , SiC, SiO ₂ , AlN, and TiO _2. Can be. The average particle diameter of the hard particles 10 can be about 1 to 50 μm.

The shaft member _2, CaF 2, CaCo _3, talcum, mica, mullite, one or more fillers 1-10 volume selected from among iron oxides, calcium phosphate and _Mo 2 C (molybdenum carbide) % May further be included. The shaft member 2 can further include one or more solid lubricants selected from MoS ₂ , WS ₂ , h-BN, and PTFE and / or 5% by volume or less of oil.

  Examples 1 to 10 and Comparative Examples 11 to 22 of the bearing device according to the present invention were produced as follows. The compositions of the sliding layers of the shaft members and the sliding members of Examples 1 to 10 and Comparative Examples 11 to 22 are as shown in Table 1.

The shaft members of Examples 1 to 10 and Comparative Examples 11 to 22 were prepared by mixing the resin (EP, PF) and hard particles (CF (carbon fiber), SiO ₂ particles) shown in Table 1 into pellets. Molded into a flat plate shape using an injection molding machine.

  The spherical graphite particles used as the raw material of the sliding member are obtained by spherically granulating scaly natural graphite, and the internal structure of the particles is such that the AB surface of the graphite crystal is rounded from the particle surface toward the inside. A structure in which a plurality of layers are laminated along a curved line, and about 10% of voids are formed inside the grains.

  In addition, the scaly graphite particles used as the raw material of the sliding member have a structure in which a large number of AB surfaces spreading in a planar shape are laminated and have a thickness in the C-axis direction perpendicular to the AB surface. On the other hand, since the thickness of the laminate is thin, the shape of the particles is a thin plate. The scaly graphite particles have no voids in the cross-sectional structure.

  The PTFE particles used as the raw material of the sliding member are PTFE particles granulated into an oval shape, and any of PTFE particles generated by suspension polymerization, PTFE particles generated by emulsion polymerization, and regenerated PTFE particles is used. It may be used.

Further, the synthetic resin (PAI, PI) particles used as the raw material of the sliding member have an average particle diameter of the synthetic resin with respect to the average particle diameter of the spherical graphite particles when the raw material of the sliding member is spherical graphite particles. What was 125% was used. In Comparative Example 17 in which the raw material of the sliding member was scaly graphite particles, the raw material synthetic resin had a particle size of 125% with respect to the average particle size of the scaly graphite particles. The solid lubricant (MoS ₂ ) used as the raw material for the sliding members of Examples 5 and 6 was used with an average particle size of 30% of the average particle size of the spherical graphite particles as the raw material. As the particles of the filler (CaCo ₃ ) of Example 6, particles having an average particle diameter of 25% with respect to the average particle diameter of the spherical graphite particles were used.

  The composition of the sliding member shown in Table 1 using the raw material of the sliding member is diluted with an organic solvent to prepare a composition having a viscosity shown in the “viscosity (mPa · s)” column of Table 1. In addition, the composition was mixed using a roll mill and the treatment for eliminating the internal voids of the spherical graphite particles (treatment time 1 hour) was simultaneously performed. In addition, the gap between the rolls of the roll mill was set so that the ratio of the average diameter of the spherical graphite particles used as the raw material of the sliding member in Examples 1 to 10 and Comparative Examples 11 to 16 and 18 to 22 was 200%. In Comparative Example 17, the ratio of the scaly graphite particles used as the raw material of the sliding member to the average diameter was 400%.

Next, the composition of the mixed sliding member was applied to one surface of the Fe alloy back metal layer, and then coated with a roll so that the composition had a predetermined thickness. In addition, the back metal layer of Examples 1-9 and Comparative Examples 11-22 used Fe alloy, and Example 10 used Fe alloy which has a porous sintered part of Cu alloy on the surface.
Next, heating for drying the solvent in the composition of the sliding member and heating for baking the synthetic resin of the composition of the sliding member were performed to prepare the sliding member. The thickness of the sliding layer of the manufactured sliding members of Examples 1 to 10 and Comparative Examples 11 to 22 was 0.3 mm, and the thickness of the back metal layer was 1.7 mm.

  The manufactured sliding member of the example was measured for the average particle diameter of the PTFE particles dispersed in the sliding layer by the measurement method described above, and the result is shown in the “average particle diameter D1” column of Table 1. Indicated. Further, the average aspect ratio (A1) of the PTFE particles described above was measured, and the result is shown in the “Aspect ratio (A1)” column of Table 1. In Comparative Examples 11 to 14 and 16 to 22, Table 1 shows the results of measuring the average particle diameter and average aspect ratio (A1) in the same manner as in the Examples.

  The sliding member of the produced example was measured for the average particle diameter of the long spherical graphite particles dispersed in the sliding layer by the measurement method described above, and the result is shown in Table 1 as “Average particle diameter D2”. Shown in the column. Further, the average aspect ratio (A2) of the oblong graphite particles described above was measured, and the result is shown in the “Aspect ratio (A2)” column of Table 1. In Comparative Examples 11 to 16 and 18 to 22, Table 1 shows the results of measuring the average particle diameter and average aspect ratio (A2) in the same manner as in the Examples.

  The sliding member of the produced example was measured for the average particle size of the scaly graphite particles dispersed in the sliding layer by the measurement method described above, and the result is shown in Table 1 as “Average particle size D3”. Shown in the column. Further, the average aspect ratio (A3) and the anisotropic dispersion index (S) of the scale-like graphite particles 72 described above were measured, and the results are shown in the “Aspect ratio (A3)” column of Table 1, “Anisotropic dispersion index”. (S) "column. Comparative Examples 11 to 15 and 17 to 22 show the results of measuring the average particle diameter, average aspect ratio (A3), and “anisotropic dispersion index (S)” in the same manner as in Example 1.

  The sliding member of each example and each comparative example was formed into a flat plate shape, and the shaft member was formed into a flat plate shape (see FIG. 1), and a sliding test was performed under the conditions shown in Table 2. The amount of wear of the sliding layer after the sliding test of each example and each comparative example is shown in the “wear amount” column of Table 1. In each example and each comparative example, the surface of the sliding member (the surface of the sliding layer) of the sliding member after the sliding test was checked for occurrence of scratches on the surface using a roughness measuring instrument. evaluated. When a scratch having a depth of 2 μm or more is measured on the sliding surface, “Yes” is indicated, and when it is not measured, “No” is indicated. In addition, in each of the examples and comparative examples, in order to evaluate the stability of the sliding performance, the friction coefficient (K1) when the number of cycles is 5000 and the friction coefficient (when the number of cycles is 20,000) ( K2) was measured, and the difference (K3 = K2−K1) between the friction coefficient (K2) and the friction coefficient (K1) was determined. These results are shown in the “Friction coefficient (K1)” column, “Friction coefficient (K2)” column, and “Friction coefficient difference (K3)” column of Table 1.

  As can be seen from the results shown in Table 1, in Examples 1 to 10, the difference K3 between the friction coefficient K2 at the end of the sliding test and the intermediate friction coefficient K1 is smaller than those in Comparative Examples 11 to 13 and 15. . Further, in Examples 4 to 9, the average aspect ratio A1 of the PTFE particles was 1.5 to 4.5, and the difference in the friction coefficient was particularly small. In Examples 4 to 9 in which the aspect ratio of the PTFE particles is 1.5 or more (4.5 or less), the difference in the friction coefficient is smaller than those in Examples 1 to 3 in which the aspect ratio is less than 1.5. However, as described above, it is considered that the surface area of the PTFE particles was increased, so that the dropping was suppressed and the transfer film was stably formed on the shaft member.

On the other hand, when the ratio of PTFE particles contained in the sliding layer is small or not contained as in Comparative Example 11 and Comparative Example 15, the PTFE formed on the shaft member as described above is used. It is considered that the difference in the friction coefficient was increased by the insufficient transfer film, which caused the transfer of graphite particles to proceed and become excessive and the friction coefficient became unstable.

In Comparative Example 12, since the ratio of PTFE particles contained in the sliding layer is as high as 2% by volume, an excessive transfer film of PTFE particles was formed at the initial stage of sliding, and thus the friction coefficient continued to decrease. It is thought that the difference in coefficient of friction has increased.

In Comparative Example 13, since the average particle size of PTFE particles contained in the sliding layer is as small as 0.5 μm, some of the PTFE particles exposed on the sliding surface slide before the transfer film is formed. It is considered that the transfer film is insufficiently formed and the difference in the coefficient of friction is increased because the falling PTFE particles are discharged from both the sliding surface and the surface of the shaft member.

  Further, in Examples 1 to 10, the wear amount of the sliding layer after the sliding test was smaller than those of Comparative Examples 14 and 16 to 22. Further, in Examples 4 to 9, the average aspect ratio A1 of the long spherical graphite particles 71 is 1.5 to 4.5, the average aspect ratio A3 of the scaly graphite particles 72 is 5 or more, and anisotropic. The dispersion index S was 3 or more, and in particular, the amount of wear was reduced. In Examples 4 to 9 in which the aspect ratio A2 of the oblong graphite particles was 1.5 or more, the amount of wear was less than that in Examples 1 to 3 in which the aspect ratio A1 was less than 1.5. This is probably because the contact area with the synthetic resin is increased and the retention by the synthetic resin is increased by increasing the surface area of the oblong graphite particles as described above.

  Further, in Examples 1 to 10, there was no scratch on the sliding surface of the sliding member after the sliding test, which is also related to the result that the amount of wear is reduced. The reason why Examples 1 to 10 suppress the generation of scratches on the sliding surface of the sliding member is that the sliding layer contains long spherical graphite particles and scaly graphite particles as already described.

  On the other hand, when the sliding layer contains only the oblong graphite particles as in Comparative Example 16 and Comparative Example 22, the hard particles exposed on the surface of the shaft member and the sliding surface are in direct contact with each other for sliding. As a result, scratches occur on the sliding surface of the sliding member. When scratches are generated on the sliding surface of the sliding member, the sliding layer is easily worn, and the amount of wear increases.

  In Examples 1 to 4, in a part of the long spherical graphite particles, fine line-shaped voids having a width of 0.1 μm or less along the lamellar structure of the graphite crystal are present in the cross-sectional structure. In these examples, the oval graphite particles were removed from the sliding surface after the sliding test, or the sliding member was slid. There were no scratches on the surface.

  In Comparative Example 14, since the particle diameter of the PTFE particles contained in the sliding layer is as large as 30 μm, the PTFE particles in the sliding layer are sheared by the load applied to the sliding layer, and the strength of the sliding layer is reduced. It is thought that the amount of wear increased.

In Comparative Example 16 and Comparative Example 22, as described above, the hard particles exposed on the surface of the shaft member and the sliding surface of the sliding member slide in direct contact, and the sliding surface of the sliding member is scratched. To do. Further, in Comparative Example 11, spheroidized graphite particles having voids therein were used as the graphite particles as the raw material of the sliding member, but the composition containing the graphite particles was diluted with an organic solvent so that the viscosity became 15000 mPa · s. Therefore, the ratio of the organic solvent in the composition is large, and the frequency of the synthetic resin particles passing through the gap between the rolls of the roll mill in the mixing process is low at the same time as passing through the gap. For this reason, the amount of deformation of the spheroidized graphite particles as the raw material in the mixing step is reduced, and as a result, the average spherical aspect particles (A2) of the long spherical graphite particles dispersed in the sliding layer are reduced, The voids formed inside the spheroidized graphite particles as the raw material remained almost as they were.
For this reason, in the sliding member of Comparative Example 11, in the sliding test, when the graphite particles exposed on the surface of the sliding layer are subjected to a load from the shaft member, the long spherical graphite particles are cracked or the internal voids are Crushed and buckling occurs, the surface area of the grains is reduced, and the retention of the oblong graphite particles by the synthetic resin is not sufficient, so that the spheroidal fragments of the oblong graphite particles fall off from the sliding surface, and the shaft member surface It is thought that wear of the sliding surface was promoted by entering the gap between the two.

As shown in Table 1, Comparative Example 17 is different from the Examples, and the sliding layer includes only scaly graphite particles. The reason why the wear amount of the sliding layer increased in Comparative Example 17 is considered as follows.
Since the sliding layer contains only scaly graphite particles in Comparative Example 17, the amount of scaly graphite particles exposed on the sliding surface is larger than that in the example. For this reason, in Comparative Example 17, the amount of scaly graphite particles falling off from the sliding surface into the gap between the shaft member surface and the sliding surface during sliding is too large, and the surface of the sliding layer is scratched. The amount of wear increased.
Further, in Comparative Example 17, since a large amount of scaly graphite particles are exposed on the sliding surface, the amount of scaly graphite particles exposed on the sliding surface increases and the amount of scaly graphite particles that have dropped off increases. Due to the presence, the wear amount of the sliding layer increased.

  In Comparative Example 18, the sliding layer includes both long spherical graphite particles and scaly graphite particles, but the volume ratio of the scaly graphite particles to the total volume of the graphite particles included in the sliding layer is too low at 5%. The formation of the transfer part of the scaly graphite particles to the surface of the shaft member during sliding was insufficient, and the sliding surface of the sliding member was damaged. For this reason, the abrasion amount of the sliding layer increased.

  In Comparative Example 19, the sliding layer includes both long spherical graphite particles and scaly graphite particles, but the volume ratio of the scaly graphite particles to the total volume of the graphite particles included in the sliding layer is too large at 45%. During the sliding, it is considered that the amount of flake graphite particles exposed on the sliding surface cracks and drops off, and the flake graphite particles dropped off increase the amount of wear of the sliding layer.

  In Comparative Example 20, since the amount of the graphite particles composed of the oblong graphite particles and the scaly graphite particles contained in the sliding layer is as small as 3% by volume, the frictional force between the sliding layer and the surface of the shaft member is lowered. It is considered that the effect was insufficient and the wear amount of the sliding layer was increased.

  In Comparative Example 21, since the amount of the graphite particles composed of the oblong graphite particles and the scaly graphite particles contained in the sliding layer is as large as 60% by volume, the strength of the sliding layer is lowered, and the wear amount of the sliding layer is reduced. Seems to have increased.

1: Sliding device 2: Shaft member 3: Sliding member 4: Back metal layer 5: Sliding layer 6: Synthetic resin of sliding member 7: Graphite particles 71: Spherical graphite particles 72: Scale-like graphite particles 8: Porous Metallic layer 9: Synthetic resin for shaft member 10: Hard particles 11: PTFE particles

Claims (11)

A sliding device comprising a shaft member and a sliding member for supporting the shaft member,
The shaft member is composed of a synthetic resin and hard particles dispersed in the synthetic resin, and the volume of the hard particles is 5 to 50% by volume of the volume of the shaft member,
The sliding member includes a backing metal layer and a sliding layer provided on the backing metal layer,
The sliding layer is composed of a synthetic resin, graphite particles and PTFE particles dispersed in the synthetic resin, and the volume of the graphite particles is 5 to 50% by volume of the volume of the sliding layer, The volume of the PTFE particles is 0.2% by volume or more and less than 1% by volume of the volume of the sliding layer,
The graphite particles are composed of long spherical graphite particles and thin plate-like scaly graphite particles, and the volume ratio of the scaly graphite particles to the total volume of the graphite particles is 10 to 40% by volume,
The cross-sectional structure of the long spherical graphite particles is such that the AB surface of the graphite crystal is laminated in a curved shape along the roundness of the particle surface from the particle surface toward the center, and the cross-sectional structure of the scaly graphite particles is: A plurality of AB surfaces of graphite crystals are laminated in the thickness direction of the thin plate shape,
The sliding device wherein the average particle diameter of the long spherical graphite particles is 3 to 50 μm, the average particle diameter of the scaly graphite particles is 1 to 25 μm, and the average particle diameter of the PTFE particles is 1 to 25 μm.   The sliding device according to claim 1, wherein an average aspect ratio of the PTFE particles is 1.5 to 4.5.   The sliding device according to claim 1 or 2, wherein an average aspect ratio of the long spherical graphite particles is 1.5 to 4.5. The scaly graphite particles have an average aspect ratio of 5 to 10,
The anisotropic dispersion index of the scaly graphite particles is 3 or more, and the anisotropic dispersion index is represented by an average of the ratio X1 / Y1 for each of the scaly graphite particles, where X1 is the value of the sliding layer. The cross-sectional structure perpendicular to the sliding surface is the length in the direction parallel to the sliding surface of the scaly graphite particles,
Y1 is a length perpendicular to the sliding surface of the scaly graphite particles in a cross-sectional structure perpendicular to the sliding surface of the sliding layer. The sliding device described in any one of the preceding items.   The synthetic resin of the said sliding layer consists of 1 type, or 2 or more types chosen from PAI, PI, PBI, PA, a phenol, an epoxy, POM, PEEK, PE, PPS, and PEI. The sliding device described in any one of the preceding items.   The said sliding layer further contains 1-20 volume% of 1 type, or 2 or more types of solid lubricant chosen from MoS2, WS2, and h-BN, Any one of Claim 1-5. The sliding device described in 1.   The said sliding layer further contains 1-10 volume% of 1 type, or 2 or more types of fillers chosen from CaF2, CaCo3, talc, mica, mullite, iron oxide, calcium phosphate, and Mo2C. 7. A sliding device according to any one of items 6 to 6.   The sliding device according to any one of claims 1 to 7, further comprising a porous metal layer between the back metal layer and the sliding layer.   The synthetic resin of the shaft member is one or more selected from PAI, PI, PBI, PA, phenol, epoxy, POM, PEEK, PE, PPS and PEI. The sliding device described in any one of the preceding items.   The said hard particle consists of 1 type, or 2 or more types chosen from carbon fiber, glass fiber, BN, Al2O3, SiC, SiO2, AlN, and TiO2, in any one of Claim 1 to 9 The sliding device described. The shaft member is
1 to 10% by volume of one or more selected from CaF2, CaCo3, talc, mica, mullite, iron oxide, calcium phosphate and Mo2C, and / or 1 selected from MoS2, WS2, h-BN and PTFE The sliding device according to any one of claims 1 to 10, further comprising 5% by volume or less of seeds or two or more kinds.