JP4569829B2 - Sliding member - Google Patents

Description

  The present invention relates to a sliding member such as a swash plate for a compressor.

  2. Description of the Related Art Conventionally, a technique for applying a solid lubricant film to a sliding surface in order to improve boundary lubricity and dry characteristics in various sliding members is widely known.

  For example, in a swash plate compressor, a swash plate that is obliquely fixed to a rotation shaft, or a swash plate that is attached to the rotation shaft and that can change an inclination angle is provided in a partitioned space in the compressor according to the rotation of the rotation shaft. The cooling medium is expanded and compressed by increasing and decreasing the volume. The swash plate slides with a sealing member called a shoe, and the cooling medium can be expanded and compressed in a predetermined space by airtight sealing.

  Lubricating between the sliding members used in the compressor as described above is usually performed by misting the lubricating oil retained inside the compressor with a circulating gas (for example, refrigerant gas) along with the operation of the compressor, It is performed by conveying to a sliding member. However, when the compressor is left in a shutdown state for a long time and then restarted, the lubricating oil adhering to the sliding member may be washed away by the flowing gas.

  By using a solid lubricating film, the seizure resistance can be improved to some extent even in dry sliding conditions where there is no lubricating oil, such as in the initial operation of the compressor. However, the solid lubricating film has a weak point that it is easily worn. On the other hand, sliding properties at high speed and high temperature are also required under fluid lubrication, and for this purpose, initial conformability is required.

  When the coating strength of the solid lubricant film is increased to improve the wear resistance, there is a problem that the conformability is deteriorated and the seizure resistance is lowered. On the contrary, if the conformability is emphasized and the coating film strength is lowered, there is a problem that the wear resistance and the dry property are lowered.

For example, Patent Document 1 below discloses that a plurality of concentric circumferential grooves are set in a solid lubricant film, and ridges are formed between adjacent grooves.
International Publication No. 2002/75172 Pamphlet

  However, in Patent Document 1, a groove structure is formed as a lubricating oil holding function. However, since the groove structure is provided, there is a possibility that the lubricating oil once held flows out through the groove.

  The present invention has been made in view of such circumstances, and provides a sliding member having a lubricating oil retaining function, excellent initial conformability, and excellent sliding characteristics even under severe sliding conditions. The purpose is to do. It is an object of the present invention to provide a sliding member with a solid lubricating film that has good friction characteristics and excellent wear resistance, particularly under fluid lubrication, boundary lubrication, and dry lubrication.

  Therefore, the present inventors have intensively studied to solve this problem, and as a result of repeated trial and error, by forming a hole that becomes an oil reservoir obliquely with respect to the sliding surface on the surface of the solid lubricant film, for example, a swash plate As a result, it was found that the lubricating oil hardly flows out even on the sliding surface that slides with respect to the gravitational direction, and the present invention was completed with excellent sliding characteristics even under dry lubrication. It came to do.

That is, the sliding member of the present invention is a sliding member having a base material and a solid lubricating film formed on the surface of the base material, and the solid lubricating film becomes an oil reservoir that opens on the sliding surface. a plurality of holes, schematic symmetrical der against the inner wall surface central axis inclined to have and the bore center axis relative to the sliding surface of the hole is, the inclination direction of the central axis of the hole slide It is arranged in two or more directions with respect to the moving direction .

  The seizure resistance is improved by forming a solid lubricating film on the substrate. In addition, by providing a plurality of holes for oil accumulation on the solid lubricating film, lubricating oil or the like can be held in the holes, and solid contact due to oil shortage at the initial stage of sliding can be reduced. Further, by forming the holes so as to be inclined with respect to the sliding surface, it is possible to prevent the accumulated lubricating oil or the like from flowing out. Further, since the inner wall surface of the hole is substantially symmetrical with respect to the central axis, the outflow of lubricating oil or the like can be further suppressed.

In the sliding member of the present invention, instead of the inclined direction of the central axis of the hole is arranged in one direction with respect to the sliding direction, that are arranged in two or more directions with respect to the sliding direction. The inclination direction of the central axis of the hole may be arranged in two directions alternately with respect to the sliding direction.

  The inclination direction of the central axis is determined by the sliding direction of the sliding member and the inclination of the sliding surface with respect to the gravity direction. For example, in the case of a sliding member that rotates and slides, the sliding direction of the sliding member is circumferential with respect to the center of the sliding member. Is arranged in a spiral shape, a spiral shape, or a radial shape with respect to the center of the sliding member in accordance with the sliding direction. In the case of a sliding member that reciprocally slides linearly, “arranged in one direction with respect to the sliding direction” indicates a direction with respect to the reciprocating direction of the sliding member. The same applies to the arrangement in two or more directions.

  The inclination direction of the central axis is also determined by the inclination of the sliding surface with respect to the gravity direction. Therefore, in a sliding member in which the inclination of the sliding surface changes during sliding, it is better that the inclination direction of the central axis of the oil sump hole for lubricating oil is arranged in two or more directions with respect to the sliding surface. .

By tilting the direction of the central axis direction of inclination of the central axis of the oil sump hole or holes are arranged in pairs with two or more directions to the sliding surface of the lubricating oil or the like are arranged in two directions and alternately, In accordance with the sliding of the sliding member, the retaining effect of the lubricating oil or the like on the sliding surface can be maintained.

  In the sliding member of the present invention, the inclination of the central axis of the hole serving as an oil reservoir is preferably an inclination having an inclination angle of 15 ° to 75 ° with respect to the sliding surface. The inclination angle is an angle representing the inclination from the sliding surface to the center axis of the hole. An inclination angle of 0 ° is parallel to the sliding surface, and an inclination angle of 90 ° is perpendicular to the sliding surface. By having the above-mentioned inclination angle, it is possible to maintain the retaining effect of the lubricating oil or the like against the inclination of the sliding surface.

  In the sliding member of the present invention, the maximum length of the opening surface of the hole is preferably 40 μm or more and 100 μm or less. The shape of the opening surface of the hole is not particularly limited. When the maximum length of the opening surface of the hole is in this range, it is possible to provide a sliding member that is excellent in workability and cost and excellent in strength.

  In the sliding member of the present invention, it is preferable that the pitch of the holes is at least 2 times and not more than 20 times the maximum length of the opening surface of the holes. By being in this range, it is possible to provide a sliding member that is excellent in cost and excellent in the strength of the lubricating film.

  In the sliding member of the present invention, the depth of the hole is preferably 5 μm or more and 40 μm or less. By having a depth in this range, it is possible to provide a sliding member that is excellent in the retention amount and strength of the lubricating oil and the like.

  In the sliding member of the present invention, the hole may be formed not in the entire sliding surface but in a specific portion where a force is applied during sliding. If it is formed in a portion where force is applied during sliding, the sliding member has excellent sliding characteristics.

  The sliding member of the present invention is preferably a compressor swash plate. When the sliding member of the present invention is used in a slanted plate such as a swash plate, the sliding characteristics are remarkably improved.

  In the sliding member of the present invention, the oil reservoir hole may be formed by a UV laser. By forming a hole with a UV laser, it is possible to form a hole with excellent cost performance and precision.

  The sliding member of the present invention comprises a base material and a solid lubricating film formed on the surface of the base material, and the solid lubricating film has a plurality of holes serving as oil reservoirs inclined with respect to the sliding surface. Thus, the retaining property of the lubricating oil or the like is excellent, thereby the initial conformability is excellent, the solid contact due to the lack of the lubricating oil or the like at the time of sliding is reduced, and the excellent sliding property is exhibited.

  The best mode for carrying out the sliding member of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic diagram showing the configuration of the sliding member of the present invention. In FIG. 1, 1 is a substrate, 2 is a solid lubricating film, and 3 is a solid lubricant.

  As shown in FIG. 1, the sliding member of the present invention has a base material and a solid lubricating film formed on the surface of the base material. The substrate is not particularly limited, and various known substrates can be used for the sliding member. Specifically, iron-based, aluminum-based, copper-based metal materials, composite materials obtained by bonding and bonding aluminum, and the like can be given. The substrate is not limited to a flat plate, but may be a cylindrical object, a spherical object, or a special curved surface.

  The solid lubricant film is a film made of a solid lubricant and a binder resin. The solid lubricant that can be used in the present invention is not particularly limited, and examples thereof include molybdenum disulfide, tungsten disulfide, graphite, polytetrafluoroethylene (PTFE), and perfluoroalkoxyethylene (PFA).

  One or more solid lubricants can be used in combination. These solid lubricants have an effect of preventing seizure as well as an effect of reducing and stabilizing the friction coefficient. Further, the content of the solid lubricating film contained in the coating material is preferably 25 to 75% by mass, more preferably 40 to 60% by mass, and since the content is within the range, the friction characteristics and the wear resistance are excellent. It becomes a solid lubricating film.

  Although binder resin is not specifically limited, A thing with high heat resistance is preferable, for example, polyamideimide, a polyimide, an epoxy resin, a phenol resin etc. are mentioned. These binder resins have a function of retaining a solid lubricant and imparting abrasion resistance. The content of the binder resin in the film is preferably 40 to 60% by mass. When the content is within this range, the retention of the solid lubricant in the solid lubricant film is maintained, and the above effect can be effectively exhibited.

In addition to the above, the solid lubricant film material can also contain additives and the like. Examples thereof include hard particles such as Al ₂ O ₃ , Si ₂ N ₄ , TiO _2, and SiO ₂ and extreme pressure agents.

  The method for forming the solid lubricant film on the substrate surface is not particularly limited. For example, the solid lubricant film material is mixed with the roughened substrate surface and applied by spraying, followed by drying and baking at 150 to 300 ° C. Can also be obtained. In addition to spray coating methods (eg, air spray, air electrostatic coating, etc.), tumbling method, dipping method, brush coating method, roll type printing method (eg, screen printing method, pad printing method, etc.), bell type rotary atomization A solid lubricating film can be formed by a method such as a mold electrostatic coating method. The thickness of the solid lubricating film is preferably 1 to 50 μm.

  The solid lubricating film formed on the substrate has a plurality of holes serving as oil reservoirs opened on the sliding surface. The central axis of the hole is inclined with respect to the sliding surface, and the inner wall surface of the hole is substantially symmetrical with respect to the central axis. FIG. 2 shows a schematic view of the holes formed in the solid lubricant film. In FIG. 2, 2 represents a solid lubricating film, 4 represents a hole, and 5 represents a central axis of the hole.

  The shape of the opening surface of the hole is not particularly limited. For example, a circle, an ellipse, a polygon, etc. are mentioned. The inner wall surface of the hole is substantially symmetric with respect to the central axis of the hole.

  FIG. 3 shows a schematic diagram of the sliding member in which holes are formed. In FIG. 3, 1 is a substrate, 2 is a solid lubricating film, 4 is a hole, and 5 is a central axis of the hole. FIG. 3A shows that the central axis is inclined in one direction, and FIG. 3B shows that the central axis is inclined in two or more directions. FIG. 4 is a schematic view showing a state where the sliding member is used in an inclined state. In FIG. 4, 1 is a base material, 2 is a solid lubricating film, 4 is a hole.

  As shown in FIGS. 2, 3, and 4, the center axis of the hole is inclined with respect to the sliding surface, and the inner wall surface of the hole is substantially symmetrical with respect to the center axis. Since the inner wall surface of the hole is substantially symmetric with respect to the central axis, even when the sliding member is used in an inclined state, the lubricating oil or the like accumulated therein is difficult to flow out.

Inclination direction of the central axis as shown in FIG. 3 (b), that are arranged in two or more directions. The inclination direction of the central axis is determined by the sliding direction of the sliding member and the inclination of the sliding member with respect to the direction of gravity. For example, in the case of a member that has a multi-directional inclination with respect to the direction of gravity and slides, the lubricating oil or the like accumulated in the hole is less likely to flow out if the inclination direction of the central axis of the hole is arranged in two or more directions. It is desirable that the inclination direction of the central axis of the hole has an inclination direction opposite to the inclination direction with respect to the gravity direction of the sliding member.

  For example, the inclination of the central axis is preferably an inclination having an inclination angle of 15 ° to 75 ° with respect to the sliding surface. By the inclination having the inclination angle in the above range, even if the sliding member is inclined and slid with respect to the direction of gravity, the outflow from the hole of the lubricating oil or the like can be suppressed.

  The maximum length of the opening surface of the hole is preferably 40 μm or more and 100 μm or less. By being in this range, it is possible to provide a sliding member that is excellent in retention of lubricating oil and the like and excellent in strength.

  In the sliding member of the present invention, it is preferable that the pitch of the holes is at least 2 times and not more than 20 times the maximum length of the opening surface of the holes. By being in this range, it is possible to provide a sliding member that is excellent in cost and excellent in the strength of the lubricating film.

  The depth of the hole is preferably 5 μm or more and 40 μm or less. By having a depth within this range, it is possible to suppress the outflow of the lubricating oil and the like and to retain the lubricating oil and the like. In addition, the sliding member is excellent in strength. The depth of the hole is preferably smaller than the thickness of the solid lubricating film.

  Further, the hole is not necessarily formed in the entire sliding surface, and may be formed in a specific portion where a force is applied during sliding. FIG. 5 shows a schematic diagram of a swash plate in which holes are formed. In FIG. 5, 6 indicates a swash plate and 4 indicates a hole. Moreover, the arrow in a figure shows the inclination direction of the central axis of a hole. As shown by the arrows in FIG. 5, the inclination direction of the center axis of the hole is arranged in one direction toward the center of the swash plate.

FIG. 6 is a schematic view of a swash plate in which holes are formed in which the inclination directions of the center axis of the holes are two directions and are alternately arranged. In the case of a swash plate as shown in FIGS. 5 and 6, as a portion to which a force is applied during sliding, there is a circumferential portion at the center of the swash plate, and a hole may be formed there. Further, in accordance with the inclination of the swash plate with respect to the gravity direction, the inclination direction of the center axis of the hole may be arranged in two directions and alternately.

  Such a hole can be formed by, for example, a UV laser.

  In the hole forming method, a swash plate is chucked on a rotating jig that can be inclined at an arbitrary angle, and the hole is formed by irradiating a laser beam after being inclined at an arbitrary angle. After forming the hole, the swash plate is rotated, and the laser beam is irradiated again, and these operations are repeated to form the hole in a circumferential shape.

  In general, laser processing can perform fine processing with high accuracy without bringing a tool or the like into contact with a workpiece. For example, by forming a hole with a UV laser, it is possible to adjust so as not to make a hole in the substrate, and to form a hole only in the solid lubricant film. Further, by adjusting the power density and pulse width of the UV laser, the opening of the hole does not melt more than the opening, and the inner wall surface of the hole can be made substantially symmetrical with respect to the central axis. As the laser, a carbonic acid laser, an excimer laser, or a semiconductor laser may be used as a processing machine.

  The sliding member having the preferred embodiment as described above can be used for a swash plate for a compressor, for example. Any sliding member that can form a solid lubricating film on the sliding surface can be used for various sliding members. For example, the sliding member of the present invention may be a piston, a shoe, an engine bore, or the like.

  Such a sliding member of the present invention can hold the lubricating oil or the like in the hole that becomes an oil reservoir even when the lubricating oil adhering to the sliding member is washed away by the flowing gas. Therefore, even when there is no lubricating oil or the like on the surface at the initial stage of operation, the lubricating oil or the like retained in the hole that becomes the oil reservoir oozes out, so that solid contact can be reduced and seizure resistance can be improved.

  In particular, the sliding member of the present invention is particularly effective for a sliding member such as a swash plate that slides with a sliding surface inclined. By using the sliding member of the present invention, a sliding member having both initial conformability and wear resistance of the solid lubricant film can be obtained.

  Examples of the sliding member of the present invention will be described below.

  A swash plate of an iron-based material (cast iron of FCD700) having a diameter of 97 mm and a thickness of 6 mm, and a solid lubricating film composition, 60% by mass of a commercially available polyamideimide resin, 20% by mass of molybdenum disulfide, and 10% by mass of graphite. % And 10% by mass of PTFE were prepared so as to have the above composition. N-methyl-2-pyrrolidone as a solvent for the resin is added to the solid lubricant film raw material composition, and the whole is mixed and deposited on the swash plate by spray coating to form a solid lubricant film with a thickness of 30 μm. did. Thereafter, firing was performed at 240 ° C. for 1 hour, and the solid lubricating film was fixed on the swash plate.

  Next, a swash plate on which a solid lubricant film was formed was drilled in a circular shape in the center of the swash plate as shown in FIG. 6 using a UV laser processing apparatus (Spectra-Physics HIPPO-355Q oscillator). .

  The hole depth was 30 μm, the hole opening surface diameter was 50 μm, and the drilling pitch was 250 mm. The angle of the central axis of the hole was 45 ° from the sliding surface, and the inclination direction was two directions relative to the inclination direction of the sliding surface at rest.

  FIG. 7 shows a metallographic micrograph of a processed cross-section obtained by drilling. When taking a photograph, a sample in which the substrate was corroded by immersion in a 3% sulfuric acid ethanol solution for about 10 seconds was used. According to FIG. 7, it can be seen that a hole in which the central axis of the hole is inclined with respect to the sliding surface is formed.

  Using the swash plate obtained as described above as a test piece, a sliding test was performed under the following conditions. The sliding test was performed assuming seizure under dry conditions (without lubricant).

  First, the test piece was immersed in refrigeration oil near room temperature for 120 minutes, and then the surface oil was wiped with a waste cloth and subjected to a test. The sliding test was performed by using a friction wear tester manufactured by Shinko Engineering Co., Ltd., rotating the test piece at a rotational speed of 2000 rpm, and pressing a 10 mm diameter SUJ2 disk with a load of 1960 N against the test surface. The specimen was slid under these conditions, and the time until the test piece and the disc were seized and locked was measured. The results and conditions are shown in Table 1. As a comparative example, a swash plate similarly formed with a solid lubricating film, which was not drilled, was used.

Implemented from Table 1 Example 1 has become longer time until seizing significantly as compared with Comparative Example 1, it was confirmed that can exhibit excellent performance as the sliding member. This is considered to be because the laser-processed hole formed in the solid lubricating film became an oil reservoir.

It is a schematic diagram showing the structure of the sliding member in embodiment of this invention. It is a schematic diagram showing the solid lubricant film in which the hole was formed of the sliding member in embodiment of this invention. FIG. 4A is a schematic view of a sliding member in which holes are formed according to the reference embodiment of the present invention, and shows an arrangement in which an inclination direction is arranged in one direction . FIG. b is a schematic view of the sliding member in which the hole is formed in the embodiment of the present invention, and shows that the inclination direction is arranged in two or more directions. It is a mimetic diagram of the state where the sliding member in the embodiment of the present invention was used inclined. It is a schematic diagram of the swash plate in which the hole in the reference form of this invention was formed. It is a schematic diagram of the swash plate in which the hole in which the inclination direction of the hole in embodiment of this invention is two directions and was alternately arranged was formed. It is a cross-sectional photograph of the swash plate which carried out the punching process in the Example of this invention.

Explanation of symbols

1, base material, 2, solid lubricant film, 3, solid lubricant, 4, hole, 5, central axis of hole, 6, swash plate.

Claims (9)

A sliding member having a base material and a solid lubricating film formed on the surface of the base material,
The solid lubricant film has a plurality of holes serving as oil reservoirs that open on the sliding surface, the central axis of the hole is inclined with respect to the sliding surface, and the inner wall surface of the hole is with respect to the central axis. Summary symmetric der is, sliding members inclined direction of the central axis of the hole, characterized in that it is arranged in two or more directions with respect to the sliding direction. The sliding member according to claim 1, wherein the inclination direction of the central axis of the bore are arranged in two directions and alternately, with respect to the sliding direction. The sliding member according to claim 1 or 2 inclination of the central axis is inclined with an inclination angle of 15 ° or more 75 ° or less with respect to the sliding surface of the hole. The sliding member according to any one of claims 1 to 3 , wherein a maximum length of an opening surface of the hole is 40 µm or more and 100 µm or less. The sliding member according to any one of claims 1 to 4 , wherein a pitch of the holes is at least 2 times and at most 20 times a maximum length of an opening surface of the holes. The sliding member according to any one of claims 1 to 5 depth of the hole is 5μm or more 40μm or less. The sliding member according to any one of claims 1 to 6 , wherein the hole is formed not at the entire surface of the sliding surface but at a specific portion to which a force is applied during sliding. It said sliding member is a sliding member according to any one of claims 1 to 7, which is a swash plate for a compressor. The hole, the sliding member according to any one of claims 1-8, which is formed by UV laser.

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