JP2008128477A - Method of manufacturing bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a bearing for a refrigerant compressor, which has improved friction wear property in boundary lubrication, mixing lubrication and fluid lubrication while securing the almost uniform structure of a completed product without releasing reactive gas which is produced during firing. <P>SOLUTION: The method of manufacturing the bearing comprises using a powder molding machine as a vertical uniaxial press for compressing and molding kneaded material containing carbon graphite aggregate and binder into a cylindrical or columnar shape (N-Step 5), wherein a carbon graphite base material formed by firing an obtained molded product (N-Step 6) has a degree of graphite crystallinity of 15-50% with X-ray diffraction and a radial crushing strength of 18.6 MPa or more. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bearing manufacturing method.

  A scroll type refrigerant compressor bearing (carbon bearing, wound bush) used in a refrigeration apparatus is used as a main bearing and a swivel bearing. This bearing is designed to be in a fluid lubrication state in steady operation. However, this bearing generates a frictional wear phenomenon that closely resembles the wear mark of boundary lubrication because a local load concentrates on the upper end portion of the main bearing, particularly in a transiently severe operating environment.

  Current materials for this bearing include bronze-filled carbon material filled with bronze (BC3) on an isotropic carbon graphite base material, and a composite of PTFE (polytetrafluoroethylene) resin coated on a steel plate sintered with bronze A wound bush material in which the material is formed into a cylindrical shape is known (see, for example, Patent Document 1 and Patent Document 2).

  The bearing using the isotropic carbon graphite base material has good wear resistance even when the sliding portion is in a boundary lubrication state, and has a track record in the market. Since this bearing is obtained by cutting a large number of block molded bodies, it takes more than two months to manufacture, and the hardness of the block molded body itself is difficult to cut. There is a problem that time is required and material loss increases during bearing processing, so that the manufacturing cost of the material increases and the supply of material corresponding to the material loss increases.

On the other hand, although a bearing using a wound bush material is inexpensive, when the sliding portion becomes unlubricated, the temperature of the sliding surface rises due to frictional heat, and the PTFE resin softens and deforms. Therefore, this bearing has a problem that the wear characteristics of the bearing are deteriorated.
Based on the above, as bearings for refrigerant compressors, the development of carbon bearings that use carbon graphite base materials with high strength and low cost that can maintain reliability even in boundary lubrication without lubrication and without lubrication has been developed. It is desired.
JP 2002-213356 A JP 2003-314448 A

By the way, as a conventionally proposed method for manufacturing a carbon material bearing, there is known a method in which a block molded body is formed by an isotropic compression molding method, and a large number of bearings are cut out from the block molded body. Here, the isotropic compression molding method is a hydrostatic pressure molding method in which a powder is put in a pre-molded rubber mold, put in a pressure vessel and covered, and hydrostatic pressure is applied from the entire circumference.
According to the isotropic compression molding method, the amount of powder entering the pressure vessel is equivalent to 500 to 1000 when converted to carbon material bearings, and a large amount of carbon material bearings can be molded at a time.
However, the block molded body produced in this way has a problem that it takes a lot of time for setup.
Moreover, since the block molded body after molding has high strength and high wear resistance, it is hard and difficult to cut. For this reason, there has been a problem that the machining cost becomes large as well as the wear of the blade in machining is large.
Further, since the carbon material bearing is porous, the cutting oil used for processing remains in the porous when wet processing is performed. If a carbon material bearing with cutting oil remaining in the porous is used in a refrigerant compressor, the cutting oil will elute into the refrigerating machine oil containing the refrigerant in the refrigerant compressor and chemically react with the refrigerating machine oil, thereby deteriorating the refrigerating machine oil. There was a problem of promotion. Further, there is a problem that the expansion valve and the capillary tube are clogged.
Furthermore, as described above, since a large amount of molding material for the carbon material bearing is put into the pressure vessel, the reaction gas is released during firing, the uniform structure of the finished product is secured, and the internal stress due to the temperature difference between the inside and outside ( There was also a problem in terms of removal of distortion) and a large amount of waste material.
In other words, the conventional manufacturing method has a problem that the manufacturing cost of the bearing is high.

  On the other hand, as a method for manufacturing a carbon material bearing, a general press molding method is known in addition to the isotropic compression molding method. However, a general press molding method is a one-side pressurizing method, and there is a problem that a low-density region is formed because the pressurizing force does not reach the corner portion on the non-pressurizing side. Furthermore, due to the low density region, there has been a problem that the strength is insufficient and cannot be used.

  Further, conventionally, since the carbon material bearing before machining has been filled with metal, it has been difficult to uniformly fill the metal. As a result, the metal filling rate of the pores becomes uneven, and a carbon material bearing with a low metal filling rate has a problem that oil film retention is lowered and boundary lubrication is likely to occur.

  The present invention has been made for the purpose of solving the above problems. In other words, the present invention provides a method for manufacturing a bearing having excellent friction and wear characteristics.

The present invention has been made to solve the above problems.
That is, a carbon graphite base material obtained by compression-molding a kneaded material containing a carbon graphite aggregate and a binder in a cylindrical or columnar shape with a powder molding machine that is a uniaxial press in the vertical direction, and firing the obtained molded product. A bearing manufacturing method characterized in that the crystallinity of graphite by X-ray diffraction is 15 to 50% and the crushing strength is 18.6 MPa or more.

The bearing manufacturing method of the present invention has better wear resistance than conventional bearings, and can shorten the time required for bearing processing and reduce manufacturing costs.
In addition, since the bearing manufacturing method of the present invention has good wear resistance, the reliability of the bearing can be improved.
Further, in the bearing manufacturing method of the present invention, the molding pressure is uniformly transmitted by the uniaxial press in the vertical direction, so that the pressurizing force reaches the corner and does not create a low density region. As a result, the lack of strength can be resolved.

  One example of a compressor used in an air conditioner or a refrigeration apparatus is a positive displacement refrigerant compressor. This positive displacement refrigerant compressor has a structure in which a motor drive unit and a compression machine unit are coupled by a single shaft, and a bearing supports a load. The shaft and the bearing are required to have mechanical and chemical practical strength in an environment of lubricating oil in which refrigerant and refrigeration oil coexist. For example, when the friction coefficient (μ) increases, the mechanical loss increases, and when the wear amount (ΔW) is large, noise and vibration are generated. When the sealability of the compressor chamber due to misalignment deteriorates, the volume efficiency decreases. .

In general, an inverter control method or a multi-refrigerant sealing method is employed for the operation of the shaft and bearing of the refrigerant compressor. The viscosity (η) of the lubricating oil, the peripheral speed (V) of the shaft, and the axial load (P). When the engine speed fluctuates over a wide range and starts up rapidly, an oil supply delay phenomenon occurs. Therefore, the lubrication mode of the shaft and the bearing shifts from fluid lubrication at steady state to medium mixed lubrication and the most severe boundary lubrication. Therefore, a refrigerant compressor having high reliability for a long time corresponding to the lubrication mode is required.
The present invention provides a bearing material and a bearing that can cope with these severe lubrication modes, and a refrigerant compressor, a refrigeration apparatus, and an air conditioner using the same.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
FIG. 1 is a schematic sectional view of a scroll type refrigerant compressor. FIG. 2 is a partially enlarged view of a portion surrounded by a one-dot chain line in FIG.

  As shown in FIG. 1, the scroll type refrigerant compressor SC has a compression mechanism portion in which a compression mechanism portion, which will be described later, is disposed above and a motor 7 as an electric mechanism portion is disposed below. The fixed scroll member 3 and the motor 7 which is an electric mechanism portion are connected via a crankshaft 5.

  The compression mechanism includes a fixed scroll member 3 in which a spiral wrap 3b is erected on a base plate 3a, and a revolving scroll member 2 in which a spiral wrap 2b is erected on a base plate 2a. The fixed scroll member 3 and the orbiting scroll member 2 are arranged so that the spiral wrap 3b and the spiral wrap 2b mesh with each other. A suction port 3c is formed in the outer peripheral portion of the fixed scroll member 3, and a discharge port 3d is formed in the central portion.

  As shown in FIG. 2, the crankshaft 5 is supported by a bearing 4 a (main bearing) disposed at the center of the frame 4. A crank 5 a protruding from the tip of the crankshaft 5 is inserted into a bearing 2 c (orbiting bearing) of the orbiting scroll member 2 and engaged with the orbiting scroll member 2.

  The Oldham joint 6 serving as a rotation prevention mechanism is a joint that allows the orbiting scroll member 2 to perform a revolving motion without rotating relative to the fixed scroll member 3. The Oldham joint 6 engages with the rear key groove 2 d of the base plate 2 a of the orbiting scroll member 2 and with the base key groove 4 d of the frame 4.

The operation of such a scroll type refrigerant compressor SC will be described with reference to FIGS.
In this scroll-type refrigerant compressor SC, when the crankshaft 5 is rotated by the motor 7, the orbiting scroll member 2 performs the orbiting motion with respect to the fixed scroll member 3 without rotating due to the eccentric rotation of the crank 5a. As a result, the refrigerant gas sucked from the suction port 3c is compressed in the compression chamber 3e formed by meshing the spiral wrap 3b and the spiral wrap 2b. The compressed refrigerant gas is discharged above the fixed scroll member 3 from the discharge port 3d. Then, the compressed refrigerant gas reaches from the upper side of the fixed scroll member 3 to the lower side of the frame 4 through the communication hole 3g (see FIG. 1) and is discharged from the discharge port 3f to the outside of the scroll sealed container 1.

As described above, the scroll type refrigerant compressor SC as described above is provided with the bearing 2c on the base plate 2a and the bearing 4a on the frame 4 respectively. And the circulating lubricating oil (refrigerating machine oil containing a refrigerant | coolant) is supplied to both the bearing 2c and the bearing 4a. In such a bearing 2c and bearing 4a, when the scroll-type refrigerant compressor SC is started or when the discharge pressure of the refrigerant is high, supply of lubricating oil is insufficient and damage such as wear and seizure is likely to occur.
However, as shown in FIG. 2, the bearings 2c and 4a of the present embodiment are press-fitted and fixed to predetermined portions of the base plate 2a and the frame 4 of the orbiting scroll member 2, respectively, so that the scroll type refrigerant compressor The reliability and durability of the SC can be improved.
Of course, at this time, the bearings 2c and 4a may be attached to predetermined positions of the base plate 2a and the frame 4 by means of shrink fitting, cold fitting, screw fitting, fitting, adhesive, or the like. Since the pressure crushing strength (crushing load) at the time of press-fitting is required to be 18.6 MPa (150 N) or more, the crushing strength of the bearings 2c and 4a is sufficient to withstand a load higher than this. Is set. The crushing strength referred to here is determined by the sintered bearing-crushing strength test method shown in JIS Z 2507. Specifically, in the bearings 2c and 4a used in the scroll-type refrigerant compressor SC shown in FIG. 1, for example, the size is an outer diameter Φ19 mm, an inner diameter Φ16 mm, and a height 14.3 mm. The crushing load of the bearings 2c and 4a is 150 N or more, and the crushing strength is 18.6 MPa or more.

  Next, an example in which the bearing of the present embodiment is used in a rotary type refrigerant compressor different from the scroll type refrigerant compressor SC described above will be described with reference to the drawings as appropriate. FIG. 3 is a schematic cross-sectional view of a rotary type refrigerant compressor. 4 is a partially enlarged view of a portion surrounded by a one-dot chain line in FIG.

  As shown in FIG. 3, the rotary type refrigerant compressor RC is different from the scroll type refrigerant compressor SC (see FIG. 1) in that the compression mechanism portion 9 is disposed below the frame 14 in the rotary sealed container 8. In addition, the motor unit 10 as an electric mechanism unit is disposed above the frame 14. And the rolling piston 13 eccentrically attached to the crankshaft 12 driven by the motor unit 10 is configured to suck and compress the refrigerant gas.

  The compressed refrigerant gas is discharged from a discharge port (not shown) to become a high-temperature and high-pressure gaseous refrigerant, and is discharged to the heat exchanger side (condenser and evaporator) constituting the refrigeration cycle via the discharge pipe 11. Is done. The heat-exchanged refrigerant is sucked into the rolling piston 13 through the suction port 13a and is compressed again by the rolling piston 13.

  As shown in FIG. 4, the bearing 15 is a bearing of the crankshaft 12 and is attached to the frame 14 by means such as press fitting, shrink fitting, cold fitting, screw fitting, fitting, bonding, and adhesive. It has been.

The bearing 15 is set to a strength that can withstand a load of 18.6 MPa (150 N) or more in terms of the pressure ring strength (pressure ring load) at the time of press-fitting.
Bearings 2c, 4a (see FIG. 2) and bearing 15 (see FIG. 4) used in the scroll type refrigerant compressor SC (see FIG. 1) and the rotary type refrigerant compressor RC (see FIG. 3) [ Hereinafter, it may be simply referred to as “bearing”] is a material in which an anisotropic carbon graphite base material is filled with a predetermined metal as described later, as will be described later in the method of manufacturing the bearing.

  Such a scroll-type refrigerant compressor SC and a rotary-type refrigerant compressor RC (hereinafter, sometimes simply referred to as “refrigerant compressor”) move (circulate) the refrigerant in the refrigeration cycle and the heat medium of the refrigeration oil. Is used to cool or heat the room. At this time, the kind of refrigerant and refrigerating machine oil used in the refrigerant compressor described above is very important in relation to the bearing. Specifically, the material eluted from the bearing into the mixture comprising the refrigerant and the refrigerating machine oil, more specifically, the carbon graphite base material to be described later, which is a component of the bearing, is 1% by mass or less, and the flock point It is desirable that no precipitate is deposited in the mixture.

  Here, “the precipitate does not precipitate in the mixture” means a state in which the precipitate is not visually detected in the flock point test. The flock point test is performed in accordance with ASTM or JIS K 2211. For example, a test piece is placed in 90% by mass of refrigerant and 10% by mass of refrigerating machine oil, and is extracted by heating under specified conditions. This is a test for cooling to −40 ° C. after the treatment and evaluating the presence or absence of the precipitated substance.

Examples of the refrigerant that realizes such a combination include at least one selected from a halogenated hydrocarbon refrigerant, a hydrocarbon refrigerant, and a natural refrigerant. That is, these refrigerant | coolants can be used individually or in combination as appropriate.
Examples of the halogenated hydrocarbon refrigerant include a fluorinated hydrocarbon refrigerant, a fluorinated bromide hydrocarbon refrigerant, a fluorinated iodohydrocarbon refrigerant, and the like.
Among these refrigerants, preferred are fluorinated hydrocarbon (HFC) refrigerants such as R410A, R404A, R407C, and R134a, fluorinated iodohydrocarbon refrigerants such as CF3I, and hydrocarbons such as R600a and R290. Examples of the refrigerant include natural refrigerants such as R744 and R717. In particular, a fluoroiodohydrocarbon refrigerant is preferable in that it has a low environmental load.

The refrigerating machine oil that realizes such a combination includes, for example, mineral oil, polyol ester (POE) oil, polyalkylene glycol (PAG) oil, polyvinyl ether (PVE) oil, polyalphaolefin (PAO) oil, and hard oil. Examples thereof include at least one selected from alkylbenzene (HAB) oils. That is, these refrigerating machine oils can be used alone or in appropriate combination.
More preferably, the amount of the substance eluted from the carbon graphite base material is 1% by mass or less with respect to the extraction solvent R141b.

  Next, a bearing manufacturing method will be described mainly with reference to FIG. FIG. 5 is a process chart for explaining the bearing manufacturing method according to the present embodiment. In FIG. 5, a comparison with the conventional process is also described in order to clarify the differentiation from the present embodiment. Incidentally, in FIG. 5, the conventional process is shown as “current material manufacturing method” surrounded by a one-dot chain line.

  In this manufacturing method, as shown in FIG. 5, first, an inorganic filler serving as an aggregate, graphite (artificial graphite, natural graphite, etc.), coke (coal, petroleum, etc.) and a binder serving as a binder (coal or For example, coal tar pitch obtained from petroleum is mixed at a ratio of 3 parts by mass of binder to 7 parts by mass of aggregate (Step 1). In this mixing, although not shown, it is desirable to add a coupling agent (a silane coupling agent, a titanium coupling agent, etc.) for uniformly dispersing the inorganic filler.

In Step 1, the inorganic filler, graphite, and coke constituting the aggregate are mixed with a mixer or the like. In this mixing, the above coupling agent is put into a mixer or the like. This coupling agent contains, for example, carbide easily forming elements such as Si, Ti, Zr, Al, Cr, and Mo. Specifically, the above-described silane coupling agent, titanium coupling agent, etc. Is mentioned.
The coupling agent can uniformly disperse the solid substance in the binder (petroleum pitch, etc.) by coating the surface of the solid substance (coke, graphite, inorganic filler). When the solid material is uniformly dispersed in this way, the torque of the kneader described later becomes less resistant and the workability is further improved.

Moreover, the abrasion resistance at the time of a heavy load can be improved by mix | blending an inorganic substance moderately. When the inorganic content is small, the bearing is too soft for the Fe-based shaft, and the bearing is likely to be worn. On the other hand, when the amount is large, the bearing is too hard for the Fe-based shaft and the shaft is shaved. For this reason, the bearing of a present Example prescribes | regulates the moderate inorganic compounding range. In addition, wear resistance at high loads can be improved by appropriately blending an inorganic material so as to have an appropriate hardness with respect to the Fe-based shaft. That is, if the hardness is low, the bearing is damaged by the load of the shaft. Conversely, if the hardness is high, the shaft is scratched and worn.
For this reason, in this embodiment, as described above, an inorganic filler is blended in the aggregate.

  Examples of the inorganic filler include those containing at least one oxide selected from Si, Fe, Mg, Al, and Ca. And when the said raw material containing this is baked and this inorganic filler becomes a carbon graphite base material, the Mohs hardness of the baked product of an inorganic filler becomes 3 or less, Preferably it becomes 1-3. ing.

In Step 2, the aggregate mixed in Step 1, the above-described binder constituting the binder, and the above-described coupling agent are mixed. This mixing is performed at a temperature of 150 ° C. to 160 ° C., for example. As a result, the binder is dispersed and mixed with the aggregate to obtain a bulk kneaded mixture.
Next, in Step 3, the bulk kneaded mixture is subjected to a pulverizer and a granulator to be subjected to particle size classification to obtain raw material pellets.
And in Step4, it mixes so that the magnitude | size of the particle | grains (raw material pellet) which carried out the particle size classification may become suitable. As a result, raw material pellets suitable for fluidity and mold filling (hereinafter, simply referred to as “raw material”) are obtained.
Next, in N-Step 5, the following mold powder molding is performed. That is, in this N-Step 5, a molded product obtained by molding the raw material into a shape close to a shape used as a single bearing of the present invention, for example, a bearing, is obtained. The “shape close to the shape used” here includes a so-called “near net shape”, and may be a shape close to the shape of the target bearing, or a plurality of target bearings may be included. The shape may be close to a continuous long raw material. In the case of a long length, a predetermined length is cut out from the raw material, and the bearing is manufactured. Further, the “shape close to the shape to be used” may be a columnar shape when the bearing is cylindrical. It will be formed in a shape.
By the way, in the manufacturing method in this embodiment, the raw materials are molds one by one using a powder molding machine so that the raw material has a cylindrical shape with an outer diameter of Φ20.5 mm, an inner diameter of Φ11.5 mm, and a height of 25 mm, for example. Molded. For this molding, for example, an ejection method molding method having upper and lower punches, a withdraw wall molding method or the like is used. A powder molding machine employing such an ejection method molding method having a vertical punch, a withdraw wall method, or the like corresponds to a “powder molding machine that is a uniaxial press” recited in the claims.

  Both of these molding methods improve the density distribution of the green compact. Both of these molding methods utilize upper and lower punches in order to prevent a decrease in density of the corner portion on the side opposite to the punch, which was a problem with conventional unidirectional die hydraulic presses. Here, the orientation of the graphite crystal when the upper and lower punches are used will be described with reference to the drawings as appropriate. FIG. 6 to be referred to is an explanatory view of a graphite polycrystalline aggregate model included in the bearing, (a) is a diagram showing a conventional random graphite aggregate, and (b) is a diagram showing an aligned plate-like graphite aggregate. It is.

  As shown in FIG. 6 (a), the conventional one that does not use the upper and lower punches forms a random graphite aggregate in which the orientations of the graphite crystals are randomly arranged. On the other hand, when the above-described upper and lower punches are used, the random graphite aggregate is an aligned plate-like graphite aggregate in which the orientations of the graphite crystals are aligned (aligned) as shown in FIG. Become. By making good use of the orientation direction, the performance of the bearing described later is further improved. FIG. 7 referred to here is a perspective view showing a graphite crystal structure.

  As shown in FIG. 7, the graphite crystal is an aggregate represented by a hexagonal crystal. The net plane [(004) plane] of this crystal has a small friction coefficient and acts as a solid lubricant. The reason why the friction coefficient is small is that the gaps between the crystals are wide and the crystals easily slip. On the other hand, the (110) plane orthogonal to the (004) plane of the hexagonal crystal is hard and has a high-strength chemical bond. Therefore, the bearing described later according to the present embodiment uses the (110) surface as a sliding surface (thrust surface) of the bearing.

  Next, in N-Step 6 shown in FIG. 5, the mold powder molded body (green molded body) which is the molded product obtained in N-Step 5 is fired. This firing is performed in a non-oxidizing atmosphere, for example, at 1000 ° C. for 0.5 months. The above-described carbon graphite base material is obtained by this firing. This carbon graphite base material has substantially the same shape as the bearing because the mold powder compact before firing has a shape close to the shape of the bearing. Further, since the carbon graphite base material is thin, there is no temperature difference between inside and outside in the firing process. As a result, there is no cracking or chipping due to distortion. And, for example, the reactive substance produced by the reaction between carbon and the inorganic filler is not left on the carbon graphite base material. In addition, the time required for firing is halved compared to the prior art.

In the carbon graphite base material thus obtained, the binder (binder) chemically completes the carbonization reaction, and becomes 90 to 99% by mass of fixed carbon and 0.5 to 10% by mass of ash. The binder before firing contains 36 to 60% by mass of fixed carbon.
Further, the volatile content of the carbon graphite base material is 1% by mass or less.
Incidentally, the fixed carbon can be measured in accordance with JIS R 7212 or JIS K 2425. Ash content can be measured according to JIS R 7223, JIS M 8812, JIS M 8511, or JIS K 2425. The volatile content of the carbon graphite base material can be measured according to JIS R 7212, JIS M 8812, or JIS M 8511.

  The above-mentioned ash is mainly composed of an inorganic substance contained in graphite, coke and the like, and an ash of an inorganic filler blended for improving the function.

The ash content can be adjusted, for example, by estimating in advance the ash content of coke or graphite used as a raw material and the ash content of the inorganic filler. Such estimation may be performed so that the ash content converted from the oxide of the inorganic filler is 0.5 to 10% by mass.
Incidentally, the ash content of coke is 0.19% by mass, the ash content of artificial graphite is 0.1% by mass or less, the ash content of scaly graphite is 1.12% by mass, and the ash content of earthy graphite is 19.6%. The ash content of the highly crystalline graphite is 0.1% by mass or less, and the ash content of the amorphous graphite is 0.33% by mass. These graphites may be used alone or in any combination.

  On the other hand, the mechanical strength and frictional wear characteristics of the carbon graphite base material (or bearing) are improved by positively blending the inorganic filler. In other words, when a very small amount of undecomposed raw material other than fixed carbon remains in the carbon graphite base material, in the bearing incorporated in the refrigerant compressor, the undecomposed raw material softens and swells and the strength thereof decreases. The undecomposed raw material is eluted into the refrigerating machine oil and the refrigerant, and is precipitated in the refrigerant flow path to obstruct the refrigerant flow. From the above, in the bearing of this example, it is important to reduce the undecomposed raw material in the carbon graphite base material, and the carbon graphite base material used for the bearing of this example has the above-mentioned range. It consists of fixed carbon and ash.

In addition, the binder from which petroleum pitch, coal pitch or the like is a raw material is generally a compound of carbon and hydrogen, the fixed carbon measured in accordance with JIS K 2425 is 55% by mass, and the rest is hydrogen or the like. It is. And a softening point is 73-92 degreeC.
Such binder undecomposed material after firing is softened in the usage environment of the refrigerant compressor and eluted into the refrigeration oil and refrigerant, thereby reducing the strength of the bearing and It causes troubles such as clogging of refrigerant piping due to deposition.

  In N-Step 6 in the bearing manufacturing method of the present embodiment, in order to suppress the occurrence of these obstacles, the raw material containing the above-described binder is thermally decomposed while being gradually heated at 400 ° C. or higher, Finally, it is baked by being heated up to 800-2000 ° C. and completely coked.

In this production method, the temperature is raised to 800 to 2000 ° C., so that the inorganic filler as a raw material reacts with carbon to prevent generation of a substance that impairs the characteristics of the carbon graphite base material. it can. Incidentally, as a method for indirectly evaluating the characteristics of the carbon graphite base material, for example, a method of performing a flock point test or a method of performing a low temperature precipitation test by a shield tube test can be cited.
And the carbon graphite base material obtained in this way is a carbon graphite base material having anisotropy. In other words, the mold powder molded body (green molded body) obtained in N-Step 5 is an aligned plate-like graphite aggregate in which the orientation of the graphite crystals is oriented. In the porous substrate, the graphite crystal has anisotropy.

The orientation of the graphite crystals in the carbon graphite substrate in this example is 1.2 or more in terms of the anisotropic ratio (Ra) represented by the following formula (1).
Ra = I ₁ / I ₂ (1)
(In the above formula (1), I ₁ is the integral intensity ratio ((110) plane of the (004) plane and (110) plane) of the graphite crystal on the sliding surface with the shaft of the bearing. Integrated intensity / integrated intensity of (004) plane), and I ₂ is an integrated intensity ratio ((110) by X-ray diffraction of the (004) plane and (110) plane of the graphite crystal in a plane orthogonal to the sliding plane. ) Represents the integral intensity of the plane / (004) integral intensity of the plane))
The basis for the anisotropic ratio of 1.2 or more will be described later.

And the crystallinity degree by X-ray diffraction of the carbon graphite base material in a present Example is 15 to 50%.
The carbon graphite base material as described above preferably has a flexural strength of 50 MPa or more and a compressive strength of 180 MPa or more, and the average area porosity determined with a microscope of the pores is 15% or less. It is desirable that

  Next, in N-Step 7, the carbon graphite base material is put into a vacuum high-pressure filling furnace. At this time, after the vacuum high-pressure filling furnace containing the molten metal (copper α solid solution) is evacuated, the carbon graphite base material is immersed in the molten metal. Next, nitrogen gas is introduced into the vacuum high-pressure filling furnace and the inside of the vacuum high-pressure filling furnace is pressurized to 1 to 20 MPa. As a result, the voids (pores) of the carbon graphite base material are filled with molten metal. In addition, as for the filling rate of a molten metal, 10-50 mass% of a product (bearing mentioned later) is desirable.

Next, in N-Step 8, the carbon graphite base material after filling is finished into the final shape of the product. This finishing process is described as “bearing process 1” in FIG.
At this time, since the shape of the carbon graphite base material before filling is substantially the same as the shape of the bearing as described above, there is little material loss in this finishing process. And the bearing of a refrigerant compressor is obtained through such finishing.

  Next, a conventional method for manufacturing a bearing (current material manufacturing method), that is, a method for manufacturing a large number of bearings from a block molded body will be described with reference to FIG. Note that Step 1 to Step 4 in FIG. 5 are shared, but conventionally, only the amount of graphite is specified. Therefore, inorganic fillers and binders (including coupling agents) are not used in the processes corresponding to Step 1 to Step 4 in the conventional bearing manufacturing method. In other words, new characteristics due to the chemical change of the substance that is the feature of the present invention (fixed carbon is 99.0% by mass or more, the strength decreases under the use environment of the compressor, softening, swelling, or extraction with refrigerating machine oil or refrigerant) It does not give rise to a property that does not produce a product). In other words, the introduction of the aggregate, binder, and coupling agent of the present example produces the above characteristics at the firing (N-Step 6) stage, and the bearing performance and reliability are improved when the bearing is processed at N-Step 8. Is done.

  As shown in FIG. 5, CIP molding is performed in O-Step 5 in the present method for producing a material. In this O-Step5, the raw materials that are appropriately mixed with the size of the particles classified in Step4 and matched to the fluidity and mold filling properties are filled into a rubber mold that makes a block material of about 200 mm x 400 mm x 800 mm, for example. The The rubber mold filled with this raw material is immersed in the liquid and is subjected to isotropic compression molding by applying hydraulic pressure from all directions. As a result, a block material precursor is formed.

  Next, in O-Step 6, the block material is baked to form the block material. The firing temperature and time are, for example, 1000 ° C. × 1 month. The graphite crystal contained in the block material thus obtained is a random graphite aggregate shown in FIG. 6A, which is a so-called isotropic carbon graphite base material.

  Next, in O-Step7, the block material is processed into a rectangular bar material in cross-sectional view. The equipment used at this time is a cutting machine such as a sawing machine. In addition, the bar material was cut to 23 mm × 23 mm × 300 mm, for example, and surface-finished so as to approximate the final shape of the bearing to 21 mm × 21 mm × 300 mm.

Next, in O-Step8, a molten metal filling process is performed in a vacuum high-pressure filling furnace as in N-Step7 except that the bar material is used instead of the carbon graphite base material used in N-Step7. Is done.
Next, the bearing is completed through bearing processing 1 of O-Step 9, bearing processing 2 of O-Step 10, and bearing processing 3 of O-Step 11. In the bearing processing 1, the bar material is processed into a cylindrical shape by a processing device such as an NC lathe. Further, in the bearing processing 2, the columnar bar material is processed into a cylindrical shape. Further, in the bearing processing 3, the bar material having a cylindrical shape is finished by a finishing device to become a target bearing.

  As described above, the current bearing molding method surrounded by the alternate long and short dash line has many processes, and the bearing material is made by cutting out from the bar material. There were problems such as bad material loss. Further, since the graphite crystal orientation is not taken into consideration in the firing stage, the performance and reliability of the bearing are insufficient unlike the bearing of this embodiment.

  Next, with reference to FIG. 8A, FIG. 8B, and FIG. 10, the porosity of the carbon graphite base material used in the bearing of this embodiment, the orientation of the graphite crystals, and the like will be described. Here, first, FIG. 8A and FIG. 8B will be described. FIG. 8A is a microscopic structure diagram of the carbon graphite base material of this example, and FIG. 8B is a diagram showing a distribution of pore diameters.

  Here, reference numeral 16 shown in FIG. 8A indicates a fired product of an inorganic filler containing Al, Si, etc. Reference numeral 17 indicates an open hole, reference numeral 18 indicates a closed hole, and reference numeral 19 indicates a closed hole. Carbon graphite is shown. Incidentally, the inorganic filler (baked product) 16 includes those blended to increase the hardness and wear resistance of the bearing, and those contained as impurities in raw materials such as graphite.

In the bearing of the present embodiment, as described above, the ash is collectively referred to as the ash of these inorganic fillers and the ash of the impurities as ash (0.5 to 10% by mass in terms of oxide of the inorganic filler). .
The open pores 17 are a gap through which a gas generated by thermal decomposition of the binder is released, and a gap formed between the raw material particles when metal powder molding is performed (see N-Step 8 in FIG. 5). There are holes left during sintering. These holes are continuous holes. As shown in FIG. 8B, these continuous holes are distributed in a diameter range of about 1 to 15 μm. These holes are filled with 50% by mass or more of metal.
Next, Table 1 shows the relationship between the molding pressure of the powder molding machine and the area porosity.

As shown in Table 1, the isotropic carbon graphite base material obtained when the molding pressure by the hydrostatic molding method is 100% has an average area porosity of 10.86% in a 100-fold microscope field of view. The anisotropic carbon graphite base material obtained when the molding pressure is 100% has an average area porosity of 9.07%.
Further, the anisotropic carbon graphite base material obtained when the molding pressure is 97% has an average area porosity of 14.13% and an molding area pressure of 95% has an average area porosity of 17.36%. It has become. This indicates that the molding load is transmitted to the contact surface of the raw material particles and further transmitted to the lower raw material particles.

  Here, FIG. 9A is a distribution diagram showing a molding pressure distribution when a raw material is compression-molded only by an upper punch in a powder molding die, and a density distribution (porosity after firing) thereby.

  When the raw material is compression-molded only with the upper punch, the raw material particles do not exhibit sufficient pressure transmission due to slip resistance of the mold wall surface. As a result, as shown in FIG. 9A, the bottom corner portion is a low-density and porous portion with a small pressure action. The porous portion having a low density deteriorates the mechanical strength and frictional wear resistance characteristics described later.

FIG. 9B is a distribution diagram showing a molding pressure distribution when a raw material is compression-molded by both an upper punch and a lower punch in a powder molding die, and a density distribution (porosity after firing) thereby. is there.
When the raw material is compression-molded by both the upper punch and the lower punch, the low-density porous portion, that is, the fragile portion generated when compression molding is performed only by the upper punch is eliminated, as shown in FIG. 9B. In addition, the porosity distribution is sound. In other words, the mechanical strength and frictional wear resistance quality of the bearing described later are greatly improved. In particular, the upper and lower parts, such as bearings, provide the punch pressure effect. For parts that require the strength required for assembly press-fitting of the compression mechanism and the concentrated load of the axial load of the compressor, the porosity and mechanical The intensity distribution works effectively. This part is filled with a metal described later at high pressure.

  Further, the closed hole 18 (see FIG. 8A) includes a binder (for example, coal tar pitch, coal pitch, petroleum pitch) and a coupling agent (for example, a silane coupling agent, a titanium coupling) serving as a binder. ) And the like are gases generated by thermal decomposition during firing and remain in the structure, and become independent vacancies. This independent hole is difficult to be filled with metal during filling.

Carbon graphite 19 (see FIG. 8 (a)) shows the structure after the mixture of raw material graphite, coke, binder (binder), coupling agent, etc. is fired, and the graphite area after firing. The rate is measured by Raman spectroscopy. The graphite crystallinity of this part can be specified by X-ray diffraction. FIG. 10 referred to here is a graph showing the relationship between the graphite crystallinity by X-ray diffraction in a carbon graphite base material and the graphite area ratio of the matrix by Raman analysis. The graphite area ratio was measured using a laser Raman spectroscopic analyzer manufactured by RENISHAW. This measurement was performed using a He—Ne laser under the conditions of a laser output of 25 mV, a wavelength of 682.8 mm ⁻¹ , a wavelength resolution of 0.2 cm ⁻¹ , and a spatial resolution of 1 μm (maximum 200 μm). The graphite crystallinity was measured using an Rigaku X-ray diffractometer (RINT2500HL). This measurement was performed using a Cu X-ray source and an X-ray output of 50 kV (250 mA). As an optical system in the X-ray diffraction apparatus, a concentrated beam with a monochromator was used, the slit DS was set to 0.5 deg, the slit RS was set to 0.15 mm, and the slit SS was set to 0.5 deg.

  The degree of crystallinity of the carbon-graphite base material is obtained by comparison by preparing a standard sample with a known raw material in advance by the ratio of the crystalline graphite peak to the peak of amorphous coke, etc. by X-ray diffraction. Is possible. Thereby, it becomes possible to prescribe | regulate the quantity and characteristic of graphite which are required for the characteristic of a bearing. Thereby, it becomes possible to prescribe | regulate the quantity and characteristic of graphite which are required for a bearing characteristic.

In this example, as shown in FIG. 10, the degree of crystallinity of the carbon graphite base material is 15 to 50%. If the degree of crystallinity is less than 15%, the lubricity of the bearing is poor, the mating shaft material is worn, and if it exceeds 50%, the wear characteristics as a bearing are inferior, which is not preferable as a bearing for a refrigerant compressor.
Moreover, the area ratio of the matrix of the carbon graphite base material by Raman spectroscopic analysis can distinguish amorphous coke and crystalline graphite by the magnitude | size of two types of peak waveforms. This area ratio is obtained by estimating the area ratio of graphite using a known standard sample. From the above, the graphite in the carbon graphite base material of the bearing used in this example is specified. This corresponds to 45 to 68% in terms of area ratio.

Next, when evaluated by a frictional wear test of a bearing obtained by using such a carbon graphite base material, it becomes as shown in FIGS.
FIG. 11 is a graph showing the relationship between the degree of graphite crystallinity and the amount of wear. FIG. 12 is a diagram showing the relationship between the average area porosity and the wear amount. FIG. 13 is a diagram showing the relationship between the anisotropic ratio and the amount of wear.

  As shown in FIG. 11, when the degree of graphite crystallinity is less than 15% (for example, 45% by area ratio of the graphite structure), the material of the mating shaft material (hardness after quenching: Hv450 or more) is high. Damaged and undesirable. On the other hand, when the degree of crystallinity exceeds 50% (for example, 58% in terms of the area ratio of the graphite structure), the wear amount is soft and exceeds the reference value.

  As shown in FIG. 12, when the area porosity is 15% or more, the wear amount of the bearing is increased and the wear amount of the shaft is also increased. This is thought to be due to the fact that the actual test surface pressure with the shaft increases as the porosity increases, and the bond strength between the particles of the bearing material decreases. Therefore, in this embodiment, the area porosity is specified to be 15% or less. In FIG. 12, the circles indicate the values of the conventional isotropic carbon graphite base material.

In the frictional wear test in boundary lubrication with the refrigerant R410A, in the winter heating operation of a refrigeration apparatus such as an air conditioner, the refrigerant is unevenly distributed from the high temperature side indoor unit to the bottom of the refrigerant compressor of the low temperature side outdoor unit. Assume that a condition occurs. Further, in rapid start-up operation and defrosting operation, it is assumed that refrigerant or refrigeration oil in which a large amount of refrigerant is dissolved is supplied to the bearing portion with a slight delay.
Under the above operating conditions (test conditions), Conventional Example 6 in FIG. 23 is a bearing material that has been used. The amount of wear was 27 μm / 2h (13.5 μm / h). The amount of bearing wear is related to the sealing performance (leakage resistance) in the gap between the cylinder and piston of the rotary refrigerant compressor, the sealing performance of the shaft and bearing of the scroll type refrigerant compressor, that is, the sealing performance of the compression chamber. ing.
Therefore, this time, 20 μm / 2h (10 μm / h) is set as a target value in order to cope with severer operating conditions and aim for higher efficiency and higher reliability. This is a target value that is necessary for continuously maintaining the volumetric efficiency in the cylinder and the volumetric efficiency of the compression chamber over a long period of time. In other words, the wear amount of the bearing is 20 μm / 2h or less (10 μm / h) or less, that is, a test load of 9.8 MPa with respect to the short-term transient severe operating condition assumed by the wear test as described above. The target value is 10 μm / h or less.
Therefore, the anisotropic ratio corresponding to the wear amount of 10 μm / h requires 1.2 as shown in FIG.

  As shown in FIG. 13, the present embodiment selects an anisotropic ratio of 1.2 or more, but the conventionally known isotropic carbon graphite base material has an anisotropic ratio of 1.0. As can be seen from FIG. 13, the specimen with an anisotropic ratio of 1.5 has a wear amount of 5.4 μm / h, whereas the conventional specimen with an anisotropic ratio of 1.0 becomes 13.6 μm / h, which is about 1 / 2.5. Double the amount of wear. Further, it was found that the one with an anisotropic ratio of 1.8 has a wear amount of about 1 / 4.6 times when the wear amount is 2.95 μm / h. As described above, in this embodiment, the anisotropic ratio is defined as 1.2 or more.

Next, the anisotropic ratio indicating the orientation of the graphite crystal by X-ray diffraction of the carbon graphite test material was measured. The results are shown in Table 2. This measurement was performed using an Rigaku X-ray diffractometer (RINT2500HL). This measurement was performed under the condition of an X-ray output of 50 kV (250 mA) using a CuX ray source. As an optical system in the X-ray diffraction apparatus, a concentrated beam with a monochromator was used, the slit DS was set to 0.5 deg, the slit RS was set to 0.3 mm, and the slit SS was set to 0.5 deg.
FIG. 14 referred to here is a perspective view of a test piece that makes the best use of the (110) plane of the graphite crystal formed when press molding.

  The anisotropic ratio here is the X-ray diffraction when the integrated intensity ratio between the sliding test surface and its right-angle plane is determined by the peak integrated intensity and the integrated intensity ratio of the (004) plane and the (110) plane. Each ratio is defined as an anisotropic ratio. That is, the anisotropic ratio is obtained by the above-described formula (1).

  As shown in Table 2, the block shape made of the isotropic carbon graphite base material of Conventional Example 1 has an anisotropic ratio of 1.025, whereas the cylindrical shaped product of Example 1 has 1. It was found to be 791.

Next, the frictional wear characteristics and the mechanical characteristics of the test piece collected from the cylindrical base material made of the carbon graphite base material used for the bearing of this example are the conventional isotropic carbon graphite base material. Contrast with
Here, the test piece will be described first. FIG. 15 is a schematic diagram showing the sampling position of the test piece on the cylindrical base material. As shown in FIG. 15, the lateral A surface indicating the test surface in a dark color is a surface in which the network surface of the graphite crystal is oriented with high density by press molding, and the (004) surface by X-ray diffraction is concentrated. Oriented surface.
On the other hand, the vertical B surface indicating the test surface in a dark color corresponds to the direction perpendicular to the A surface, and the (004) surface is the least and the (110) surface is the most oriented.

  Next, the friction and wear characteristics and mechanical characteristics described above were evaluated for such a test piece T. First, a mating material (SCM) was formed in a cylindrical shape with the oblique line surface of each test piece T as a sliding surface, and a frictional wear test was performed in the gas of refrigerant R410A. The results are shown in Table 3. In addition, the test method of the friction wear test in the gas of R410A is the same as the friction wear evaluation test method of the metal-filled carbon graphite base material described later.

  As shown in Table 3, when the B surface is a sliding surface in Example 3 (molding pressure -3%), the wear amount of the test piece T is the test piece of the isotropic carbon graphite base material of Conventional Example 2. The wear amount of the counterpart material is equal to or less than 1/3 of that of the isotropic carbon graphite base material of the conventional example 2, but when the A surface is a sliding surface in Example 4, the wear of the test piece T The amount increases 1.65 times that of Conventional Example 2.

  Further, in Example 5 in which the molding surface is 5% and the B surface is a sliding surface, the wear amount of the test piece T is 2.2 times that of the conventional example 2, and the wear amount of the counterpart material is 2.5 times. . In addition, the friction coefficient of Example 5 at this time is 1.4 times larger than that of Conventional Example 2. As described with reference to FIG. 12, this occurs due to the porosity. That is, when the molding pressure is lowered from -3% to -5%, the density of the green powder decreases, the porosity increases, the mechanical strength decreases, the test surface pressure increases in the actual test, and the forced orientation degree of the graphite crystal decreases. It is thought to be.

  Further, the thermal conductivity (W / m · K) of the B surface of Example 3 is about 1.16 times better than that of Example A. This macroscopically represents the anisotropic ratio of graphite. Further, in Example 2 (molding pressure -0%), the wear amount of the test piece T is 1 / 1.5 compared with the test piece T of the isotropic carbon graphite base material of Conventional Example 2, The amount of wear was 1/3, confirming that it was excellent. This is an effect of the orientation of the graphite crystal in this example.

  Further, the mechanical properties of Example 2 (molding pressure-0%) are the same as the isotropic carbon graphite base material of Conventional Example 2 and the crushing load (crushing strength) is the same, and the bending strength and hardness are slightly higher. Although it was low, it turned out that it was a level which is satisfactory practically. Moreover, the regulation of bending strength and compressive strength required for the bearing is not clarified in the conventional one. That is, a bending strength of 50 MPa or more applied to the bearing during press-fitting corresponds to a crushing load of 150 N (compression crushing strength of 18.6 MPa) or more, and this embodiment defines this. Further, the compressive strength of 180 MPa or more corresponds to the load resistance of the bearing and the shaft. That is, if the compressive strength is weak, the shaft (shaft) is broken and abnormal wear occurs. When strong, it was found that the damage can be kept very small, so that reliability can be secured.

Next, the result of the thermochemical stability test of the carbon graphite base material used for the bearing of a present Example is demonstrated.
A shield tube test (150 ° C., 40 days) was performed on a combination of a typical refrigerant used in an air conditioner, a refrigerator, a water heater, and the like and a refrigerating machine oil (viscosity grade). And the appearance, the low temperature precipitation property (−40 ° C.) of the eluate, the increase in the total acid value due to the deterioration of the refrigerating machine oil, and the change in the bending strength of the carbon graphite base material were studied. The results are shown in Table 4.

As shown in Table 4, in the evaluation of the compatibility of the HFC refrigerants of R410A, R134a, R407C, and R404A with ester oil (POE) and polyvinyl ether oil (PVE oil), both refrigeration oil, low temperature precipitation, and bending strength No abnormality is observed. In addition, no abnormality was observed in the combination of the hydrocarbon refrigerant of R600a or R290 and mineral oil (MO) as described above. Furthermore, a similar test was performed using a high-pressure vessel with a combination of R744 (CO ₂ ), R717 (NH ₃ ), PAG, and MO, and after taking out after the test, R134a was newly enclosed and a low-temperature precipitation test was performed. No abnormalities were found in the samples, which proved to be good. From these, it became clear that it is practically suitable as a bearing material for a refrigerant compressor used in the coexistence of the refrigerant and refrigeration oil.
Although not shown in Table 4, in the suitability evaluation of the extraction solvent R141b, no abnormality was observed in the refrigerating machine oil, the low temperature precipitation, and the bending strength.

  Moreover, since the baked carbon graphite base material has voids, there is a problem that the frictional wear characteristic and the mechanical strength characteristic are lowered when the operation state is severe. This is presumably because the lubricating oil permeates through the holes and the hydraulic pressure distribution decreases.

Hereinafter, the improvement of this point will be described with reference to FIGS. 16 to 18. FIG. 16 is a conceptual diagram showing a bearing model of a porous carbon graphite base material, (a) is a conceptual diagram showing a model before metal filling, and (b) is a concept showing a model after metal filling. It is a figure, (c) is a figure showing the lubrication model of a journal bearing. FIG. 17 is a diagram illustrating a state diagram and mechanical properties of the filled metal. (A) is a copper - Mechanical properties of the solid solution of tin (tensile strength: sigma _B, Hardness: H _B, elongation: [delta]) is a diagram showing the relation, (b) copper - phosphorus - tin It shows a ternary metallic state, and is a diagram showing an area range of an α solid solution and an area range of α + Cu ₃ P in this example. FIG. 18 is a diagram showing the electrode potential of a typical filled metal.

  First, as shown in FIG. 16 (a), the bearing 20 is a bearing made by processing a carbon graphite base material having porous holes before metal filling, and the shaft 21 is a quench-hardened shaft. The bearing 20 rotates in the clockwise direction (clockwise) in a range from a low speed to a high speed (the rotation speed indicated by N in FIG. 16 is, for example, 800 to 8000 rpm). Reference numeral 22 denotes a lubricating oil mixed with refrigerating machine oil and a refrigerant, and this lubricating oil 22 is drawn between the shaft 21 and the bearing 20 by the rotation of the shaft 21 and has a wedge action, so that the shaft 21 is shown in FIG. Lift as shown in (a). If this lifting force overcomes the axial load P, so-called fluid lubrication occurs and metal contact can be prevented. That is, wear of the bearing due to contact can be prevented. However, when the axial load P is high or the lubricating oil viscosity is low, the hydraulic pressure due to the wedge action penetrates into the bearing, and the hydraulic pressure distribution decreases. In this state, sufficient fluid lubrication cannot be maintained. That is, as shown in FIG. 16C, a boundary lubrication region and a fluid lubrication region are mixed, and a so-called mixed lubrication region is entered. As described above, this state occurs due to a severe operation state or the like, and does not cause a problem during normal operation. The bearing 20 shown in FIG. 16 (b) according to the present embodiment is one after the porous holes are filled with metal. When this bearing 20 is used, the penetration of the lubricating oil can be suppressed extremely small. That is, the hydraulic pressure distribution B is greatly improved as compared with the hydraulic pressure distribution A before filling (see FIG. 16A). This is shown in the hydraulic pressure distribution A and the hydraulic pressure distribution B (see FIGS. 16A and 16B).

  Next, a so-called severe operation that rapidly raises the refrigerant compressor to a high speed will be described. The refrigerant compressor is in a state in which no oil film is formed between the bearing 21 and the shaft 20 at the start of operation even if the oil supply method is different. When the shaft 21 is rotated in the absence of this oil film (time lag), metal contact occurs and heat is generated, and wear and galling are reached. In the winter heating operation mode, since the refrigerant is condensed and unevenly distributed in the outdoor unit of the air conditioner, the refrigerant gathers at the lower part (bottom part) of the compressor to form a so-called sleeping state. The refrigerant present at the bottom is supplied between the shaft 20 and the bearing 21 through the shaft 21. Lubricating oil containing a large amount of this refrigerant has extremely low viscosity and extremely small oil film formation, resulting in boundary lubrication. When operating in this state, metal contact is caused and the refrigerant and refrigerating machine oil are decomposed as heat is generated, so-called corrosive wear and galling phenomenon occur. In order to eliminate such wear and galling phenomenon, in this embodiment, in the bearing 20a shown in FIG. 16B, long-term reliability is considered in consideration of wear resistance and corrosion resistance in the pores of the carbon graphite base material. The optimal metal that secures the properties is selected and filled. The conventional bearing is obtained by filling carbon graphite with one metal selected from Group IB, Group VIII excluding Fe, and Sn, or an alloy mainly composed of these metals.

Next, selection of a filling metal that ensures long-term reliability and improves wear resistance and corrosion resistance will be described.
Carbon graphite is a precious substance, and in the presence of trace amounts of moisture with base metals, such as refrigeration cycles and refrigerant compressors, it is thought that corrosion and refrigerant decomposition are accelerated by electrochemical action. It is done. Selection of the filling metal was conducted by examining chemical changes in the refrigerating machine oil when immersed in a refrigerating machine oil (ester type) containing 100 ppm of various filling candidate metals and kept at 250 ° C. for 1 hour. The results are shown in Table 5.

  As shown in Table 5, it was found that Sn (tin) solder containing Pb (lead) and an active substance (flux) cannot be used due to an abnormally high fatty acid concentration. On the other hand, Al (aluminum) has a small amount of fatty acid, but reacts with the base material at the time of filling to produce a composite carbide. Further, Cu (copper) has a small amount of fatty acid but is soft, so that improvement in mechanical strength due to reinforcement is poor. Furthermore, Zn (zinc) and Sn (tin) have a fatty acid concentration that is about twice that of Cu (copper).

  Also, solute metals in oil are 36 ppm for Pb (lead), 16 ppm for Sn solder, and all other metals are 0.1 ppm or less (out of detection limit). No significant difference could be found.

  In this example, in order to increase the mechanical strength, which is a defect of Cu, and to prevent a chemical reaction with the carbon graphite base material, a metal such as Sn (tin), Zn (zinc), Si (silicon) or the like is used. In addition to alloying, in order to suppress the production of fatty acids, the range of α solid solution was specified and filled. As the α solid solution, Cu (copper) -2.3% Be (beryllium), Cu (copper) -5.0% Si (silicon), Cu (copper) -9.7% Al (aluminum), Cu (copper) ) -12% Sn (tin), Cu (copper) -29% Zn (zinc), etc., but Be (beryllium), Si (silicon) and Al (aluminum) are reactive with carbon graphite base materials at high temperatures. Therefore, it is necessary to devise a method to minimize the reaction when filling. Cu (copper), Sn (tin), and Zn (zinc) have very little reaction at the filling temperature near the melting point, and are suitable for work. Therefore, here, a Cu (copper) -Sn (tin) based alloy will be described.

FIG. 17 referred to here is a diagram showing a phase diagram and mechanical properties of the filled metal, and (a) is a mechanical property (tensile strength: σ _B , hardness: H _{B in a} copper-tin based solid solution. (B) shows the copper-tin-phosphorus ternary metal state, the area range of the α solid solution and the area range of α + Cu ₃ P in this example. FIG. FIG. 18 is a diagram showing the electrode potential of a typical filled metal.

The Cu (copper) -Sn (tin) alloy has a relationship between the metal phase diagram shown in FIGS. 17A and 17B and the mechanical properties, and the α solid solution has about 12% Sn (tin). It becomes a range. At this time, the tensile strength σ _B is about 1.8 times, the hardness is about 1.6 times, and an improvement effect is obtained by filling the holes. On the other hand, since the α solid solution of Cu (copper) has a base metal such as elution Zn (zinc), Sn (tin), Si (silicon), etc. described above, dissolved in the structure of Cu (copper). As shown in FIG. 18, the corrosion potential of the object apparently becomes an electrode potential at the same level as that of pure copper. In other words, the α solid solution can greatly improve the mechanical strength and have the same corrosion resistance as that of pure copper. Especially in the refrigerant compressor and the refrigerating apparatus, the electrode potential of the carbon graphite substrate and the α of Cu (copper) The potential difference of the solid solution can be reduced, and the reliability with corrosion can be greatly improved.

Further, as shown in Table 5, bronze [Cu (copper) + Sn (tin)], phosphor bronze [Cu (copper) + Sn (tin) + P (phosphorus)], phosphorus, which can be used for the bearing of this example. Copper [Cu (copper) + P (phosphorus)] can be kept at a low fatty acid concentration that approximates that of pure copper. Furthermore, as a means of enhancing the mechanical strength of the α solid solution, mechanical strength is obtained without impairing the properties of the carbon graphite base material by dissolving or partially depositing P (phosphorus) in the form of Cu ₃ P. Further, it is possible to improve the friction and wear resistance characteristics, which is one object of this embodiment. Note that typical copper alloys used in the filling experiments are JIS (Japanese Industrial Standards) BC3, PBC3, and BCuP2. In order to verify that 10 to 50% by mass of a metal that strengthens the structure is filled, for example, one bearing before and after metal filling described later (see FIGS. 20A and 20B) The amount of metal may be obtained by subtracting the mass before filling from the mass after filling to determine the amount of metal, and dividing this by the mass after filling. Here, the reason for prescribing 10 to 50% by mass is the result of selecting the best workability, and it is difficult to make a product exceeding 50% by mass and 10% by mass or less in the current filling furnace. Because. Further, when the amount is 10% by mass or less, not only the workability is deteriorated, but also the mechanical strength or the friction and wear characteristics are significantly lowered.

Next, means for filling a carbon graphite base material with a copper alloy that forms an α solid solution of Cu (copper) and material characteristics after filling will be described.
FIG. 19 is a schematic view showing an example in which an alloy forming an α solid solution of Cu (copper) is melted in a vacuum high-pressure filling device, and the pores of the carbon graphite base material are high-pressure filled. FIG. 20 (a) is a schematic diagram showing a cross-section cut out from a block-shaped isotropic carbon graphite base material, and FIG. 20 (b) is a columnar or cylindrical anisotropic carbon graphite base. It is a schematic diagram which shows a material. FIG. 21A is a microstructural view before filling the metal of the anisotropic carbon graphite base material, and FIG. 21B is a microscopic structure view after the metal filling of the anisotropic carbon graphite base material.

First, a vacuum high pressure filling apparatus for filling a carbon graphite base material with a copper alloy will be described here.
As shown in FIG. 19, the vacuum high-pressure filling device 23 has a metal melting furnace 25, a hanging basket 26, and an elevator 27 in a vacuum container 24. Then, after setting the carbon graphite base material to be filled in the hanging cage 26, the vacuum high pressure filling device 23 is evacuated and the gas is discharged. Next, the copper alloy is heated and melted with an α solid solution of Cu (copper) in the metal melting furnace 25. Then, the carbon graphite base material to be filled is immersed in the suspension basket 26 using the elevator 27 in this heated and melted copper alloy bath. The heat-melted copper alloy corresponds to the “metal melt” described in the claims.

  Next, an inert gas such as nitrogen gas is injected from the injection port 28, and the pressure in the metal melting furnace 25 is increased to a high pressure of, for example, 10 MPa, and this high pressure is maintained. As a result, the vacant portion of the filled carbon graphite base material is forcibly filled with the copper alloy. As the pressure for pressurization and filling, for example, 20 MPa for a diameter of 1 μm and 10 MPa for 2 μm are required, corresponding to the hole distribution diagram of FIG. In normal performance, the hole filling rate is 62 to 90% at 10 MPa. When the molding pressure is small and the pores are large, about 50% filling is possible even at 1 MPa.

  Thereafter, the hanging cage 26 is raised and cooled to a temperature below the solidus of the copper alloy, and the solidification of the metal is completed. Thereafter, high-pressure gas is discharged to the atmosphere, and the inside of the vacuum high-pressure filling device 23 is brought to normal pressure. In this state, the metal-filled carbon graphite base material is taken out from the vacuum high-pressure filling device 23.

Here, in this example, the carbon graphite base material is formed into a cylindrical shape close to the shape to be used, and then filled with a copper alloy. The metal concentration of the copper alloy around the inner and outer peripheral surfaces of the graphite base material is almost uniform. This is due to the following reason.
When the molten copper alloy is filled in the cylindrical carbon graphite base material, the copper alloy is filled from the outer peripheral surface and the inner peripheral surface, so that the metal concentration on the inner peripheral surface and the outer peripheral surface is almost uniform. It has become. Therefore, even in the case where the machining finishing process is performed, it is possible to obtain the bearing of the final use form in which the metal concentration on the entire inner peripheral surface and the outer peripheral surface is substantially uniform.
On the other hand, in the case of a columnar carbon graphite base material, since the metal is filled from the outer peripheral surface toward the center of the cylinder, the metal concentration of the copper alloy in the cylindrical body is almost equal to the distance from the center to the outer peripheral surface. It is uniform. Therefore, even if it is a case where it processes from a cylindrical body to a cylindrical body by a machining finishing process, the metal concentration of the perimeter of an inner peripheral surface and an outer peripheral surface is substantially uniform. In addition, even when the columnar carbon graphite base material is processed into a cylindrical body before filling the metal, the copper alloy is filled from the outer peripheral surface and the inner peripheral surface as described above. The metal concentration on the entire circumference of the surface is almost uniform. Therefore, even in the case where the machining finishing process is performed, it is possible to obtain the bearing of the final use form in which the metal concentration on the entire inner peripheral surface and the outer peripheral surface is substantially uniform.

  As shown in FIGS. 20 (a) and (b), for example, the bearing used for the refrigerant compressor is a bar when the outer diameter Φ is set to 19 mm, the inner diameter Φ is set to 16.0 mm, and the height (not shown) is set to 15 mm. Made from wood and cylindrical material. In the case shown in FIG. 20 (b), the bearing is fabricated by processing the cylindrical material so that the outer diameter is 20.5 mm, the inner diameter is 11.5 mm, and the height is 25 mm. In addition, the said dimension is the example added to the final shape in order to include a clamp margin. Incidentally, in the example shown in FIG. 20A, the step of processing a bar material into a column (see O-Step 9 in FIG. 5), the step of processing from a column into a cylinder (see O-Step 10 in FIG. 5), and the column An example is shown in which the final finished dimensions are obtained through a finishing step (see O-Step 10 in FIG. 5). That is, the phantom line shown with the dashed-dotted line in Fig.20 (a) represents the final finishing dimension.

  When the bar material shown in FIG. 20 (a) is compared with the cylindrical material shown in FIG. 20 (b), the cylindrical material shown in FIG. 20 (b) has a metal filling ratio of the bar material shown in FIG. 20 (a). 1/5, the volume ratio is 2/5, and the effective area ratio of the filled metal in the carbon graphite base material is 13/60. And when comparing the bar material shown in FIG. 20 (a) and the cylindrical material shown in FIG. 20 (b), the amount of heat drawn out during immersion, the amount of metal taken out, the filling time, the production capacity, etc. It was demonstrated that the bearing manufacturing method of the example (see FIG. 5) is excellent.

  Next, the mechanical and physical properties of the carbon graphite base material filled with metal will be described with reference to Table 6. Table 6 summarizes the mechanical and physical properties of the carbon graphite base material filled with metal.

  Conventional Example 3 in Table 6 is one in which isotropic carbon base material with an average area porosity of 10.86% shown in Table 1 is filled with bronze (BC3: P content 0), The area filling rate was 7.66%, and the area porosity corresponding to unfilled was 0.86%. The area hole filling rate is 90%.

Hereinafter, as the carbon graphite base material according to this example, an example in which the average area porosity shown in Table 1 is 9.07% and a cylindrical anisotropic carbon graphite base material is filled with metal will be described. To do.
Example 6 was filled with bronze (BC3) and had an area filling rate of 6.49% and an area porosity of 1.31%. The area hole filling rate is 83%.
Example 7 was filled with phosphor bronze (PBC3: P content 0.05 to 0.5 mass%), with an area filling factor of 4.82% and an area porosity of 2.98%. became. The area hole filling rate is 62%.
Example 8 was filled with phosphoric copper (BCuP2: P content 6.8 to 7.5% by mass), with an area filling factor of 6.10% and an area porosity of 1.54%. became. The area hole filling rate is 80%.

Next, as a carbon graphite base material according to this example, the average area porosity shown in Table 1 is 9.07%, and a cylindrical anisotropic carbon graphite base material is filled with metal. explain.
Example 9 was filled with bronze (BC3), and had an area filling rate of 6.13% and an area porosity of 1.70%. The area hole filling rate is 78%.
Example 10 was filled with phosphor bronze (PBC3) and had an area filling rate of 7.40% and an area porosity of 0.98%. The area hole filling rate is 88%.
Example 11 was filled with phosphor copper (BCuP2), and the area filling rate was 6.52% and the area porosity was 1.63%. The area hole filling rate is 80%.

  Further, as shown in Table 6, the bending strength, compressive strength, and crushing strength (crushing load) of Examples 6 to 11 are smaller in each item compared to Conventional Example 3 ( It can be confirmed that a bending strength of 50 MPa or more and a compressive strength of 180 MPa or more, which are targets for the bearing base material, are secured. Furthermore, it can also be confirmed that a crushing strength (crushing load) of 18.6 MPa (150 N by crushing load) or more is secured in a cylindrical test product having an outer diameter of Φ19 mm, an inner diameter of 16 mm, and a height of 14.3 mm.

  FIG. 21 is a microstructure diagram of Example 6 of the anisotropic carbon graphite substrate in Table 6 before (a) and after (b) filling with metal. In FIG. 21, black portions indicate pores and gray sea portions indicate carbon graphite base materials. In addition, the organization chart of Fig.21 (a) which shows the state before filling with a metal is B surface of an anisotropic carbon graphite base material when the shaping | molding pressure demonstrated in Example 2 of Table 3 is set to 100%. Is shown. FIG. 21 (b) shows the structure after filling with the metal, and the blank on the B surface of the anisotropic carbon graphite base material when the molding pressure described in Example 2 in Table 3 is 100%. The micrograph when a hole is filled with metal is shown. The white part indicates a filled metal, and the black part indicates an unfilled part. That is, it shows a state in which 62 to 90% of the metal is filled in the holes that are hindered with respect to the mechanical strength and the lubricating oil film.

  As described above, the anisotropic carbon graphite base material according to this example (Examples 6 to 11 shown in Table 6) has an area vacancy filling rate of 62 to 90%, and has a mechanical strength. In addition, since 62 to 90% of the holes that are hindering the lubricating oil film are filled with metal, the mechanical strength and the performance against the lubricating oil film can be improved. It was confirmed that the mechanical strength (bending strength, compressive strength, crushing strength) satisfies the strength required for the bearing.

  Tables 7 and 8 evaluate the thermochemical stability of the carbon-graphite base material filled with metal against a mixture of refrigerant and refrigerating machine oil.

  The test conditions shown in Table 7 and Table 8 conform to the shield tube test specified by JIS K 2211 (refrigeration machine oil). That is, 5 mL of refrigerating machine oil (ester oil) containing 100 ppm of water, 0.5 g of refrigerant (R410A), and carbon graphite produced in a size (length 3 mm × width 4 mm × length 50 mm) that can be placed in a glass tube in advance. The base material was enclosed in a glass tube, and a heating test at 150 ° C. for 40 days, which was assumed as the usage environment of the bearing in the refrigerant compressor, was performed. And the reliability concerning the thermochemical stability after a heating test is evaluated. Example 12 in Table 7 is an anisotropic carbon graphite base material filled with phosphor bronze (PBC3), and Example 13 is an anisotropic carbon graphite base material filled with phosphor copper (BCuP2). . And, the amount of acidic substance which is a product when the refrigeration oil is chemically decomposed by a refrigerant, etc., a precipitation test of a solute that visually checks the appearance at room temperature and in a condition of being left in an environment of −40 ° C. for 4 hours. Each test of the total acid value test to be confirmed and the fatty acid test in which the amount of free fatty acid present in the refrigerating machine oil was analyzed by gas chromatography were performed before and after the heating test. As a result, it was confirmed that there was no significant difference in all test results before and after the heating test. This is equivalent to Conventional Example 4 (isotropic carbon graphite base material filled with bronze (BC3)). Moreover, also in the bending test using the carbon graphite base material concerning Examples 12 and 13, it has confirmed that there was no significant difference before and behind a heating test. From the above, it has been confirmed that there is no problem in using the carbon graphite base material according to the present example as a bearing material.

  Also, an anisotropic metal-filled carbon substrate (length 3 mm × width 4 mm × length 50 mm) and one of HFC refrigerants R134a, R407C, R404A or hydrocarbon (HC) refrigerants R600a, R290 (0.5 g), Refrigerating machine oil (ester oil) 5 mL containing 100 ppm or 500 ppm of water was sealed in a glass tube, and a heating test at 150 ° C. × 40 days assumed for the use environment of the bearing in the refrigerant compressor was performed. And the result of having evaluated the reliability concerning the thermochemical stability after a heating test is shown in Table 8. In Table 8, Examples 14 to 27 are in the anisotropic carbon graphite group filled with the metal described in the infiltrated metal column, the refrigerant described in the refrigerant column, and the refrigerator oil column. The combination of the described refrigeration oil and the test is shown. Also in these results, no abnormality was observed after the heating test in terms of hue change, presence / absence of appearance precipitates, bending strength, and total acid value, and it was confirmed that the bearing was practical. Moreover, in the analysis of the metal in refrigerating machine oil performed at the same timing as the evaluation shown in Table 7 and Table 8, Cu (copper), Sn (tin), and P (phosphorus) are below the detection limit (<0.01 ppm). And good corrosion resistance was confirmed. This was not significantly different due to the difference in the amount of water contained in the refrigerating machine oil (100 ppm, 500 ppm), and it was confirmed that the same corrosion resistance was exhibited at any moisture content.

To summarize the above, the carbon graphite base material according to the present example is an HFC refrigerant (R134a, R404A, R407C, etc.) represented by R410A, an ester refrigerant oil, an HC refrigerant represented by R600a, R290, and mineral oil ( MO) has high practical reliability in chemical stability.
Although not shown in Table 8, it has been confirmed that the chemical stability with the extraction solvent R141b has high reliability in practical use. That is, the substance eluted in the usage environment of the extraction solvent R141b was 1% by mass or less, and no precipitate was visually detected in the flock point test.

Next, put CO ₂ refrigerant (R744), PAG refrigerating machine oil (water content 150ppm), and filled metal carbon graphite base material specimen into a metal pressure vessel, and thermochemical stability in the usage environment of the refrigerant compressor The reliability related to sex was evaluated. The amount of CO ₂ refrigerant used at this time was 40 g, the amount of refrigerating machine oil was 40 mL, and the test was a heating test at 150 ° C. × 40 days. Also in this test, no abnormality was observed in the test items such as hue, bending strength, total acid value, etc., compared with the blank described above. In addition, since the visual test of an external appearance check cannot be performed in the said metal container, the refrigerating machine oil and refrigerant | coolant (R134a) after a test are enclosed with the hard glass tube mentioned above, and the eluted substance is visually determined. Again, it was confirmed that there was no precipitate at room temperature and -40 ° C. Further, it has been found that the ammonia refrigerant has high reactivity with copper, and thus has poor appearance and low temperature precipitation and is not practical.

Hereinafter, with reference to FIGS. 22 to 25, the friction and wear characteristics of the metal-filled carbon graphite base material assuming the use environment of a refrigerant compressor such as an air conditioner and a refrigeration apparatus will be described.
FIG. 22 is a diagram showing the arrangement of the frictional wear test pieces. FIG. 23 is a diagram in which a frictional wear test using R410A as a gas refrigerant was performed, and the wear amount measured in this test was compared between the conventional example and this example. FIG. 24 is a diagram in which a frictional wear test using R410A as a gaseous refrigerant was performed, and the average friction coefficient measured in this test was compared between the conventional example and this example. FIG. 25 is a diagram in which a frictional wear test using CO ₂ as a gaseous refrigerant was performed, and the wear amount measured in this test was compared between the conventional example and this example.

The frictional wear test piece is composed of a fixed piece 29 and a movable piece 30 as shown in FIG. The fixed piece 29 is assumed to be a bearing, and the movable piece 30 is assumed to be a shaft (steel of H _V 450 or higher: for example, carburizing and quenching of SCM415, surface accuracy Rz = 1.2 μm or lower). In addition, when performing an evaluation test using the fixed piece 29 and the movable piece 30, the shape and size of the frictional wear evaluation test can be performed under the high-pressure atmosphere of the refrigerant assuming the operating atmosphere of the refrigerant compressor. The fixed piece 29 and the movable piece 30 are formed.
Table 9 shows the test conditions for the evaluation test of the fixed piece 29 and the movable piece 30.

  This test condition is a severe acceleration test condition under boundary lubrication operation assuming a non-lubricating oil state. In other words, the test conditions are such that the test surface pressure corresponds to the bearing surface pressure, and the test condition is equivalent to the peripheral speed of the shaft. It is a condition that the lubricating oil does not reach the shaft and the bearing portion at the start-up or the like.

Next, as shown in FIG. 23, the anisotropic carbon graphite cylinders and columnar substrates of Examples 28 to 34 filled with bronze (BC), phosphor bronze (PBC), and phosphor copper (BCuP) In any case, it was found that the amount of wear was improved to about ½ as compared with the case where the isotropic carbon graphite base material of Conventional Example 5 was filled with bronze (BC). Further, the isotropic carbon graphite base material of Conventional Example 5 was also obtained by filling the block molded body of the isotropic carbon graphite base material of Examples 33 and 34 with phosphor bronze (PBC) and phosphor copper (BCuP). It was confirmed that the amount of wear was lower than that of a material filled with bronze (BC). This is a compounding effect of the copper alloy containing phosphorus (Cu ₃ P). That is, Conventional Example 5 is the same isotropic carbon graphite base material but does not contain phosphorus, so that the wear amount of the bearing is 6 μm / 2 h, whereas Example 33 is 5.1 μm / 2 h. is there. In addition, Example 34 was 3.4 μm / 2h. Therefore, it was found that the abrasion amount was improved in Examples 33 and 34 as compared with Conventional Examples 5 and 6. Furthermore, Conventional Example 6 has the above-described graphite crystallinity of 86% (Examples 28 to 34 have a graphite crystallinity of 15 to 50%) and a low mechanical strength. There is a difference in the amount of wear.

  Next, as shown in FIG. 24, the isotropic carbon graphite base material is phosphor bronze (PBC) as compared with the conventional example 5 in which the isotropic carbon graphite base material is filled with bronze (BC). Example 34 filled with phosphor, Example 33 filled with phosphor copper (BCuP), Example 32 filled with bronze (BC) in a cylindrical molded body of anisotropic carbon graphite base material, Filled with phosphor bronze (PBC) Example 31, Example 30 filled with phosphor copper (BCuP), Example 29 filled with a cylindrical molded body of anisotropic carbon graphite base material and bronze (BC), and phosphor bronze (PBC) In Example 28, the friction coefficient decreases in proportion to the content of P (phosphorus) in the filling metal. Therefore, it can be understood that the α solid solution of Cu (copper) containing P (phosphorus) is filled in the network pores of the carbon graphite base material, the material strength is increased, and the friction coefficient is reduced.

Next, as shown in FIG. 25, in the frictional wear test using the CO ₂ refrigerant as the gas refrigerant, the wear amount of the conventional isotropic carbon graphite base material is 2 μm / h or less. The wear amount of the anisotropic carbon graphite base material of this example is also 2 μm / h or less. In addition, an isotropic carbon graphite base material filled with bronze (infiltrated product) is almost the same as an anisotropic carbon graphite base material filled with bronze (infiltrated product), and the amount of wear is the same. Abnormally increases. When the test surface pressure as a condition of this friction and wear test is 20 MPa, a tribochemical reaction occurs between the refrigerant and the filled metal on the friction surface, and wear progresses. In this case, the unfilled base material alone is superior. I found out. Accordingly, it has been found that there is no significant difference in isotropicity and anisotropy between the base material and the filled product in terms of wear in the CO ₂ refrigerant, and it can be put to practical use.

  Next, test results obtained by performing an abrasion test by changing the test surface pressure using the anisotropic carbon graphite base material of this example as a fixed piece 29 (see FIG. 22) will be described with reference to the drawings as appropriate. FIG. 26 is a diagram showing a result of a wear test performed in R410A as a gaseous refrigerant by changing the test surface pressure in a range of 5 to 15 MPa. In addition, as described above, R134a, R410A, R407C, R404A, and the like can be given as the refrigerant targeted in this embodiment, but the constituent elements are C (carbon), F (fluorine), and H (hydrogen). Corrosion wear related to the tribochemical reaction under the environment is represented by R410A used as a refrigerant in this test.

In addition, as described above, the refrigerating machine oil targeted by this example includes POE (ester oil), PVE (ether oil), and the like. In this test, POE was used as the refrigerating machine oil.
In the above-described air wear test (see FIGS. 23 and 24), the test was performed at a constant speed of 1.2 m / s and a test surface pressure of 9.8 MPa in R410A as a gas refrigerant. The air wear test was performed at 5 MPa and 15 MPa before and after the above air wear test. Other conditions were set as shown in Table 10.

  In the load resistance test, the test piece was immersed in a mixed lubricating oil of refrigerant R410A and polyol ester refrigerating machine oil (VG68), and the test surface pressure was continuously increased in the range of 1.8 to 98 MPa. Then, when the test surface pressure reached 98 MPa (Max pressure), the load resistance test was finished and the amount of wear was measured. Other conditions are as described in Table 10.

  As shown in FIG. 26, in Conventional Example 7, when the test surface pressure becomes 9.8 MPa and the test surface pressure becomes 15 MPa, wear increases rapidly and reaches 16 μm / h. Further, in Conventional Example 8, the wear amount when the test surface pressure was 9.8 MPa was 12 μm / h, but when the test surface pressure was 15 MPa, the wear amount increased to 20 μm / h. In Example 35, the wear amount when the test surface pressure was 9.8 MPa was 2 μm / h or less, but the wear amount when the test surface pressure was 15 MPa was 14 μm / h. In Example 36, the wear amount at a test surface pressure of 9.8 MPa was 2 μm / h or less, but the wear amount at a test surface pressure of 15 MPa was 3.7 μm / h. 1/3 or less.

  FIG. 27 is a diagram showing a result of an abrasion test assuming mixed lubrication in a mixed liquid of refrigerant and refrigerating machine oil with the surface pressure changed from 1.8 to 98 MPa, (a) isotropic carbon. The figure which measured the relationship between the surface pressure of graphite (block), and a friction coefficient, (b) is the figure which measured the relationship between the surface pressure of anisotropic carbon graphite (cylinder), and a friction coefficient. 28 (a) and 28 (b) are diagrams showing the relationship between the surface pressure and the friction coefficient of the anisotropic carbon graphite of this example filled with metal, and FIG. 28 (c) is a conventional isotropic filled with metal. It is a figure which shows the relationship between the surface pressure of a conductive carbon graphite, and a friction coefficient. FIG. 29 is a diagram showing a comparison test result of shaft and bearing wear amounts in the test result of FIG.

  FIG. 27 (a) shows the load resistance of the isotropic carbon graphite base material. As shown in FIG. 27 (a), in this wear test, the friction coefficient increases rapidly from the test surface pressure of 23 MPa. As a result, the friction surface was broken, and the test piece itself was broken at a test surface pressure of 60 MPa.

  FIG. 27 (b) shows the load resistance of the anisotropic carbon graphite base material. As shown in FIG. 27 (b), in this wear test, the test piece itself was broken at a test load of 75 MPa. In the wear test of FIG. 27B, the same characteristics as the isotropic carbon graphite base material are shown.

  FIGS. 28 (a), (b) and (c) show load resistance when an anisotropic carbon graphite substrate is filled with a metal, and are shown in FIGS. 28 (a), (b) and (c). As described above, in this wear test, the friction coefficient of the anisotropic carbon graphite + phosphorus bronze, the anisotropic carbon graphite + phosphorus copper, and the isotropic carbon graphite + bronze was about 0.1 or less. In this abrasion test, it was found that the load resistance is drastically improved by the presence of the oil film surface.

FIG. 29 shows a representative example of the amount of wear at the completion of the test of FIG. 28 (a). As shown in FIG. 29, in the conventional example 9, the amount of wear of the fixed piece is 80 μm / 2h, and the movable piece Wear amount of the fixed piece is 352 μm / 2h, and wear amount of the movable piece is 3.2 μm / 2h.
In Example 37, the wear amount of the fixed piece is 5 μm / 2h and the wear amount of the movable piece is 1.2 μm / 2h. In Example 38, the wear amount of the fixed piece is 13 μm / 2h and the wear amount of the movable piece is It was 2.5 μm / 2h.

  From the above test results, in the mixed lubrication state and boundary lubrication state under severe operating conditions of the refrigerant compressor, those in which the anisotropic carbon graphite base material is filled with bronze (BC) and phosphor bronze (PBC) are particularly It was confirmed to be excellent.

To summarize the above, a solid solution of Cu (copper) containing P (phosphorus) is filled in the gap between the raw material particles on the B surface of a molded body such as a column or cylinder of a carbon graphite base material. strength is high, for example bronze (BC) is _H V 117, phosphor bronze (PBC) is _H V 128, copper-phosphorus (BCuP) is _H V 105, these hard and brittle carbon graphite substrate _(H V 146 ˜211) is believed to reinforce the carbon graphite substrate.

  Next, about the test results when the example products having the above test results are incorporated into an R410A refrigerant compressor such as a refrigeration system, and a compressor is subjected to a limit strength test by a high-speed intermittent operation of inverter startup with a large amount of refrigerant enclosed. explain. In the test results, the conventional product (isotropic carbon graphite block molding base material + bronze (BC) filling) and the example (anisotropic carbon graphite cylindrical base material + phosphor bronze (PBC) filling) were used for shafts and bearings. Almost no trace of sliding was observed on each friction surface, and good results were shown in terms of wear amount and oil deterioration. Similarly, in the refrigerator, no abnormality was found as a result of the long-term reliability evaluation of the combination of R600a and mineral oil and the combination of R134a and ester oil using a reciprocating compressor. Furthermore, in the hot water heater, no abnormality was found as a result of long-term reliability evaluation in the combination of R744 and PAG oil using a scroll compressor. In other words, it is confirmed that the bearing of this embodiment satisfies the operating conditions of the conventional refrigeration apparatus or compressor under normal use conditions, and further has characteristics superior to those of the conventional product in the severe test as described above. It was made.

  Next, in order to clarify the bearing characteristics in the normal low load region, the refrigerant is stored in the refrigerant compressor having the characteristics shown in FIG. 16C while referring to FIGS. 30A and 30B. Sommerfeld number when the viscosity (η) at a predetermined temperature of the refrigeration oil in which the refrigerant is dissolved, the test surface pressure (P) of the shaft and the bearing, and the peripheral speed (V) are changed. The relationship of the friction coefficient with respect to (Stribeck curve) will be described by comparison between the conventional carbon graphite substrate and the carbon graphite substrate in this example.

Fig. 30 (a) is a diagram showing a Stribeck curve of an anisotropic carbon graphite substrate, and Fig. 30 (b) is a diagram showing a Stribeck curve of an isotropic carbon graphite substrate.
In this test for obtaining the Stribeck curve, the test load is 1 MPa, 2 MPa in a mixed practical atmosphere (viscosity η: 26 × 10 ⁻³ Pa · s) of 40 ° C., refrigerant (R410A), and refrigerating machine oil (ester type). A Stribeck curve at 3 MPa was determined. As is clear from FIGS. 30 (a) and 30 (b), in the case of a test load as low as 1 MPa, ηv / P is superior to the isotropic carbon graphite base material than the isotropic carbon graphite base material. I understand that. This is considered to be derived from the fact that the average porosity of the substrate is 10.86% isotropic and 9.07% anisotropy (see FIG. 8).

  Next, with reference to FIGS. 31 (a) and 31 (b), a predetermined refrigerating machine oil in which refrigerant stored in the refrigerant compressor in the refrigerant compressor having the characteristics shown in FIG. 16 (c) is dissolved is dissolved. The relationship between the Sommerfeld number and the coefficient of friction (Stribeck curve) when the viscosity at the temperature of (η), the test surface pressure (P) of the shaft and the bearing, and the peripheral speed (V) are changed. The comparison is made between the conventional carbon graphite substrate and the carbon graphite substrate in this example.

FIG. 31 (a) is a diagram showing a Stribeck curve of a conventional isotropic carbon graphite base material, and FIG. 31 (b) is a conventional isotropic carbon graphite base material + bronze (BC) metal filling. It is a figure which shows the Stribeck curve of an isotropic carbon graphite base material.
This test for obtaining the Stribeck curve is based on the above-mentioned conventional isotropic carbon graphite base material, or a bearing and shaft formed of a conventional metal-filled isotropic carbon graphite base material, and HFC refrigerant and refrigerating machine oil. This was performed assuming the case of sealing together with a predetermined amount of R410A representing the above.

At this time, the temperature of the refrigerating machine oil is limited to 40 ° C., 60 ° C., and 80 ° C., the test surface pressure is limited to 1 MPa, 2 MPa, and 3 MPa, and the peripheral speed is 0.012 m / s to 1.2 m / s. It was carried out on the assumption that the viscosity was limited to the range, and the practical viscosity (η) in the refrigerant compressor was limited to a range of 9.5 × 10 ^{−3 to} 26 × 10 ⁻³ Pa · s. In this test, the fixed piece 29 and the movable piece 30 shown in FIG. 22 were used. The results of evaluating each obtained Stribeck curve were as follows.

  As shown in FIG. 31 (a), the coefficient of friction of the isotropic carbon graphite substrate increases rapidly when ηv / P becomes 10 [(Pa · s · m / s) / (GPa)] or less. However, the mechanical loss due to the friction of the bearing is large under the environmental conditions of high test surface pressure, low speed and low viscosity. It is desirable that ηv / P is 10 [(Pa · s · m / s) / (GPa)] or more.

  As shown in FIG. 31 (b), the metal-filled isotropic carbon graphite base material has ηv / P of 1.2 [(Pa · s · m / s) / (GPa) as in FIG. 31 (a). )] Use above is desirable.

FIG. 32 (a) relates to the present example and is a diagram showing a Stribeck curve of an anisotropic carbon graphite base material + phosphorus bronze (PBC) metal-filled anisotropic carbon graphite base material. .
As shown in FIG. 32 (a), this metal-filled anisotropic carbon graphite base material has an ηv / P of 0.9 [(Pa · s · m / s) / (GPa) at axial loads of 1 MPa and 2 MPa. )] Maintains a low friction region and enters a so-called fluid lubrication state to reduce the mechanical loss of the shaft and the bearing. Therefore, it is excellent in initial conformability and lubricating oil film retention, and can sufficiently withstand use under low viscosity, low speed rotation (for example, 1000 rpm) and high load.

FIG. 32 (b) shows that, among the test conditions for obtaining the Stribeck curve in FIG. 32 (a), the temperature 60 ° C. was changed to the temperature 80 ° C., and the viscosity 14 × 10 ⁻³ Pa · s was changed to the viscosity 9.5 ×. It is a figure which shows the Stribeck curve calculated | required when it changes to 10 ^<-3 > Pa * s. As can be seen from the measurement results of FIGS. 31 (b), 32 (a) and 32 (b), the lubricating condition of the working fluid in which the refrigerant and the refrigerating machine oil coexist is at least η (the Sommerfeld number of the shaft and the bearing). Viscosity or viscosity coefficient) V (peripheral speed) / P (load) is desirably 0.8 [(Pa · s · m / s) / (GPa)] or more, and in this test, bearing mechanical loss is small. I was able to confirm. In addition, the average surface pressure (axial load) of the Sommerfeld number of the shaft and the bearing in the lubrication condition of the working fluid in which the refrigerant and the refrigerating machine oil coexist is at least 0.15 to 20 MPa, and the amount of wear of the bearing is small. I understand. In the refrigerant compressor including the bearing manufactured based on the above results, the mechanical loss due to the friction of the bearing is reduced, and the amount of wear is also reduced. Therefore, according to this bearing, the sound and vibration of the refrigerant compressor are reduced, the sealing performance of the compressor chamber due to misalignment is improved, and the reduction in volumetric efficiency (ηV) can be prevented. As a result, according to this bearing, it is possible to obtain a refrigerant compressor and a refrigeration apparatus that can ensure power saving and reliability.

FIG. 33 is a diagram schematically showing the Stribeck curve of the carbon graphite base material. As shown in FIG. 33, the metal-filled product has a significantly improved friction coefficient when ηv / P is the same as that of the unfilled product, and a fluid lubrication region having a particularly low friction coefficient can be formed.
Note that the refrigeration apparatus using the bearing in this embodiment includes home and commercial air conditioners, refrigerators, dehumidifiers, water heaters, washing and drying machines, showcases, refrigeration units, automobile air conditioners, and the like.

Since the bearing according to the present embodiment has the above-described configuration, the following effects can be obtained.
That is, a carbon graphite base material obtained by compressing a mixture containing a carbon graphite aggregate and a binder into a cylindrical shape or a columnar shape by a powder molding machine that is a uniaxial press in the vertical direction, and firing the obtained molded product. This is a bearing manufacturing method in which the crystallinity of graphite by X-ray diffraction is 15 to 50% and the crushing strength is 18.6 MPa or more. To explain in detail, a mixture of carbon graphite aggregate material mixed with kneading and having an appropriate particle size distribution by granulation and classification is filled into a cylindrical mold, and the molding pressure is made uniform by the upper and lower punches. This is compacted so that the pores generated between the raw material particles are small and dense. The green molded body (molded body formed by the mold powder molding process) is coked and fired over a suitable temperature and time, and the graphitization reaction is performed so that the graphite crystallization rate falls within a range of 15 to 50% by mass. Production management is performed, and the anisotropic carbon graphite base material of this embodiment can be provided. Moreover, since the crushing strength is 18.6 MPa or more, it is possible to provide a bearing that sufficiently satisfies the practical strength.

  Further, the kneaded material is a method for manufacturing a bearing further including an inorganic filler. Therefore, the above-described effects can be obtained, and the wear resistance at high loads can be further improved. That is, it can be provided that the bearing can be prevented from being damaged by the load of the shaft, or the shaft can be scratched and worn.

  Further, the carbon graphite base material has a bending strength of 50 MPa or more and a compressive strength of 180 MPa or more. Therefore, the carbon graphite base material improves the base material characteristics by manufacturing and controlling the sintering bond and void distribution between the raw material particles, and the bending strength and compressive strength after filling the metal exceed the specified values. Can be provided.

  In addition, the carbon graphite base material is cylindrical, and the carbon graphite base material is filled with a metal melt, and the metal concentration on the inner peripheral surface and the outer peripheral surface is made substantially uniform by a machining finishing process. did. Therefore, a cylindrical carbon graphite base material is introduced into a vacuum filling device, and after evacuation, the filled metal is melted at a temperature above the liquidus, filled with high pressure after immersion, and then filled into the pores. The manufacturing method of pulling up and cooling to a temperature below the solidus temperature, and then returning to normal pressure and taking out is a short filling distance from the inner and outer circumferences of the bearing and acts evenly. And a bearing capable of securing a crushing strength of 18.6 MPa or more can be provided.

  In addition, the carbon graphite base material has a columnar shape, is formed in a cylindrical shape through the center of the carbon graphite base material, and the obtained cylindrical carbon graphite base material is filled with a metal melt. By the machining finishing process, the metal concentration on the entire inner peripheral surface and outer peripheral surface was made substantially uniform. Therefore, a cylindrical carbon graphite base material is introduced into a vacuum filling device, and after evacuation, the filled metal is melted at a temperature above the liquidus, filled with high pressure after immersion, and then filled into the pores. The manufacturing method of pulling up and cooling to a temperature below the solidus temperature, and then returning to normal pressure and taking out is a short filling distance from the inner and outer circumferences of the bearing and acts evenly. And a bearing capable of securing a crushing strength of 18.6 MPa or more can be provided.

  In addition, a metal melt was high-pressure infiltrated at a pressure of 1 to 20 MPa into the carbon graphite base material having an area porosity of 15% or less determined with a microscope. Therefore, the pore distribution of the carbon graphite base material is in the range of about 1 to 15 μm, and the osmotic pressure is 20 MPa or more for the pore diameter of about 1 μm due to the surface tension of the filled metal and the contact angle with the carbon graphite base material. Similarly, it is estimated that a high pressure of 10 MPa or more is required for about 2 μm, and it is possible to provide a bearing capable of obtaining an area hole filling rate of at least 50% of the holes. Thereby, the oil film retainability as a bearing is improved, and boundary lubrication can be made difficult to occur.

  Moreover, it is used for the bearing for refrigerant | coolant compressors of a refrigerator, Comprising: The substance eluted to extraction solvent R141b is 1 mass% or less. Therefore, since coking of the raw material is 99% by mass or more with fixed carbon, no flux is used for machining, such as flux for filling, and in the elution refrigerant R141b test, 1% by mass of the elution substance from the bearing components to the elution refrigerant is obtained. Manufacturing management can be as follows. Further, it is possible to provide a bearing with extremely few obstacles to the refrigerant piping accompanying elution.

It is a cross-sectional schematic diagram of the scroll-type refrigerant compressor in which the bearing which concerns on a present Example is integrated. It is the elements on larger scale of the location enclosed with the dashed-dotted line of FIG. It is a cross-sectional schematic diagram of the rotary type refrigerant compressor in which the bearing which concerns on a present Example is integrated. It is the elements on larger scale of the part enclosed with the dashed-dotted line of FIG. It is process drawing for demonstrating the manufacturing method of the bearing which concerns on a present Example. It is explanatory drawing of the graphite polycrystal aggregate | assembly model contained in a bearing, (a) is a figure which shows the conventional random graphite aggregate | assembly, (b) is a figure which shows an alignment plate graphite aggregate | assembly. It is a perspective view which shows a graphite crystal structure. (A) is a microscope organization chart of the carbon graphite base material of a present Example, (b) is a figure which shows distribution of a hole diameter. (A) is a distribution diagram showing a molding pressure distribution when a raw material is compression-molded only with an upper punch in a powder molding die, and a density distribution (porosity after firing) thereby, (b) is a powder molding It is a distribution map which shows the molding pressure distribution at the time of carrying out the compression molding of the raw material by both the upper punch and lower punch in this metal mold | die, and the density distribution (void ratio after baking) by it. It is a figure which shows the crystallinity of a carbon graphite base material, and the area ratio of the graphite structure | tissue by a Raman analysis. It is a figure which shows the relationship between graphite crystallinity and the amount of wear. It is a figure which shows the relationship between an average area porosity and an abrasion loss. It is a figure which shows the relationship between an anisotropic ratio and the amount of wear. It is a perspective view of the test piece which utilized the (110) surface of the graphite crystal | crystallization formed when it press-molds to the maximum. It is the schematic diagram which showed the collection position of the test piece in a cylindrical body base material. It is a conceptual diagram which shows the bearing model of a porous carbon graphite base material, (a) is a conceptual diagram which shows the model before metal filling, (b) is a conceptual diagram which shows the model after metal filling, (c ) Is a diagram showing a lubrication model of a journal bearing. It is a figure showing the phase diagram and mechanical characteristic of a filling metal. (A) is a copper - Mechanical properties of the solid solution of tin (tensile strength: sigma _B, Hardness: H _B, elongation: [delta]) is a diagram showing the relation, (b) copper - phosphorus - tin It shows a ternary metallic state, and is a diagram showing an area range of an α solid solution and an area range of α + Cu ₃ P in this example. It is a figure which shows the electrode potential of a typical filling metal. It is a schematic diagram which shows an example which melts the alloy which forms alpha solid solution of Cu (copper) in a vacuum high-pressure filling apparatus, and carries out high-pressure filling of the hole of a carbon graphite base material. (A) is a schematic diagram showing a rectangular bar material with a cross section cut out from a block-like isotropic carbon graphite base material, and (b) is a schematic diagram showing a columnar or cylindrical anisotropic carbon graphite base material. FIG. (A) is the microstructural view before the metal filling of the anisotropic carbon graphite base material, (b) is the microstructural view after the metal filling of the anisotropic carbon graphite base material. It is a figure which shows arrangement | positioning of a friction abrasion test piece. It is the figure which performed the friction abrasion test using R410A as a gaseous refrigerant | coolant, and compared the abrasion loss measured by this test with a prior art example and a present Example. It is the figure which performed the friction abrasion test using R410A as a gaseous refrigerant | coolant, and compared the average friction coefficient measured by this test with a prior art example and a present Example. Perform frictional wear test using CO ₂ as a gaseous refrigerant, a diagram comparing with the wear amount measured in this test with a conventional example and the present embodiment. It is a figure which shows the result of having changed the test surface pressure in the range of 5-15 MPa, and having done the abrasion test in R410A as a gaseous refrigerant. It is a figure which shows the result of the wear test supposing mixed lubrication in the liquid mixture of a refrigerant | coolant and refrigerating machine oil, changing a surface pressure to 1.8-98 MPa, (a) is isotropic carbon graphite (block) The figure which measured the relationship between the surface pressure of this, and a friction coefficient, (b) is the figure which measured the relationship between the surface pressure of anisotropic carbon graphite (cylinder) and a friction coefficient. (A) And (b) is a figure which shows the relationship between the surface pressure of the anisotropic carbon graphite of a present Example filled with a metal, and a friction coefficient, (c) is the conventional isotropic carbon graphite filled with a metal. It is a figure which shows the relationship between a surface pressure and a friction coefficient. It is a figure which shows the abrasion amount comparison test result of the axis | shaft and bearing in the test result of Fig.28 (a). (A) is a figure which shows the Stribeck curve of an anisotropic carbon graphite base material, (b) is a figure which shows the Stribeck curve of an isotropic carbon graphite base material. (A) is a figure which shows the Stribeck curve of the conventional isotropic carbon graphite base material, (b) is the metal filling isotropic carbon of the conventional isotropic carbon graphite base material + bronze (BC). It is a figure which shows the Stribeck curve of a graphite base material. (A) is based on a present Example, The figure which shows the Stribeck curve of the metal filling anisotropic carbon graphite base material of an anisotropic carbon graphite base material + phosphor bronze (PBC), (b) Among the test conditions for obtaining the Stribeck curve in (a), the temperature was changed from 60 ° C. to 80 ° C., and the viscosity was changed from 14 × 10 ⁻³ Pa · s to 9.5 × 10 ⁻³ Pa · s. It is a figure which shows the Stribeck curve calculated | required when it changed. It is the figure which modeled the Stribeck curve of a carbon graphite base material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Scroll sealed container 2 Orbiting scroll member 2a Base plate 2b Wrap 2c Bearing 2d Back keyway 3 Fixed scroll member 3a Base plate 3b Wrap 3c Suction port 3d Discharge port 4 Frame 4a Bearing 5 Crankshaft 5a Crank 6 Oldham joint 7 Motor 8 Sealed container for rotary 9 Compressor part 10 Motor part 11 Discharge pipe 12 Crankshaft 13 Rolling piston 13a Suction port 14 Frame 15 Bearing SC Scroll type refrigerant compressor RC Rotary type refrigerant compressor

Claims (7)

  X-ray of a carbon graphite base material obtained by compressing a kneaded material containing carbon graphite aggregate and a binder into a cylindrical shape or a cylindrical shape with a powder molding machine that is a uniaxial press in the vertical direction, and firing the obtained molded product A method for producing a bearing, characterized in that a graphite crystallinity by diffraction is 15 to 50% and a crushing strength is 18.6 MPa or more.   The bearing manufacturing method according to claim 1, wherein the kneaded material further includes an inorganic filler.   The bearing manufacturing method according to claim 1 or 2, wherein the carbon graphite base material has a bending strength of 50 MPa or more and a compressive strength of 180 MPa or more.   The carbon graphite base material is cylindrical, and the carbon graphite base material is filled with a metal melt, and the metal concentration on the inner peripheral surface and the outer peripheral surface is made substantially uniform by a machining finishing process. The manufacturing method of the bearing as described in any one of Claim 1 thru | or 3 characterized by the above-mentioned.   The carbon graphite base material is cylindrical, and is formed in a cylindrical shape through the center of the carbon graphite base material. The obtained cylindrical carbon graphite base material is filled with a metal melt, The bearing manufacturing method according to any one of claims 1 to 3, wherein the metal concentration in the entire circumference of the inner circumferential surface and the outer circumferential surface is made substantially uniform by a machining finishing step.   4. The metal melt is filled at a pressure of 1 to 20 MPa into the carbon graphite base material having an area porosity of 15% or less determined by a microscope. 5. The manufacturing method of the bearing of description.   The carbon graphite base material is used for a bearing for a refrigerant compressor of a refrigerator, and the amount of the substance eluted in the extraction solvent R141b is 1% by mass or less. The manufacturing method of the bearing as described in any one of claim | item 6.