JP3003889B2 - Sliding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding material having excellent sliding characteristics under mixed lubrication and boundary lubrication conditions. More specifically, the present invention relates to a backing metal and a sintered body formed on the surface of the backing metal. The present invention relates to a sliding material including a Cu or Cu alloy sintered layer, and a synthetic resin and a solid lubricant filled in spaces of sintered particles of the sintered layer.

[0002]

According to JP-A-55-106230, polyimide and 30% by weight or less of molybdenum disulfide, graphite and the like are added to voids of spongy metal such as Cu having a porosity of 88 to 98%. A sliding member filled with an agent is known. This sliding member uses a spongy metal having a very high porosity as a base material for holding a filling substance. Therefore, in order to form a spongy metal, which is usually produced by sintering, into a predetermined bearing shape, it is usually necessary to perform a punching process as shown in the embodiment of the publication, and in addition to the problem of reduced yield, Therefore, there is a problem that the workability is inferior to that of the sliding material using the back metal.

According to JP-B-63-37445,
A back metal, a Cu or Cu alloy sintered layer sintered on the surface of the back metal, and a synthetic resin and a solid lubricant filled in the space of the sintered particles of the sintered layer; And a sliding material in which the surface of the filling material is machined to be substantially coplanar.

[0004]

[Problems to be Solved by the Invention]
According to the description of the manufacturing method for manufacturing the sliding material of No. 445,
A lead-bronze powder having a substantially spherical diameter of 0.18 mm is sintered on a backing metal and machined so as to have a thickness of 0.11 mm. The material surface is getting. If the sintered layer is composed of one layer of metal particles, the surface exposure rate fluctuates greatly due to the machining allowance, and the sliding characteristics are not stable. Also, if a sintered layer is created by stacking two or more metal particles and then machined, if the metal particles are stacked in close packing, the surface exposure rate should be constant regardless of the cutting allowance. However, it actually depends on the cutting amount (cutting allowance) as shown in FIG.

FIG. 4 shows that spherical powder having an average particle size of 110 μm is stacked and sintered in approximately three layers (partially two or four layers), and has a thickness of about 300 μm and a volume of about 35% by volume. A sintering layer having a porosity of is formed, and a resin is impregnated into the entire sintering layer so as to protrude further from the surface of the sintering layer by about 20 μm to form a sliding layer, which is cut by machining. It is the graph which calculated | required the relationship between the cutting amount (micrometer) and the surface exposure rate of a sintered layer. From this graph, it can be seen that in order to stabilize the surface exposure rate, the sintered particles stacked in multiple layers must be cut by 100 μm or more.

[0006] In the sliding material of the above-mentioned Japanese Patent Publication No. Sho-sho, solid lubricants such as molybdenum disulfide and graphite are 30% by weight.
The following is described as being desirable. The amount of solid lubricant is 3
When the content is 0% by weight or less, the effect of the solid lubricant is not sufficiently exhibited because the amount of components such as polyimide and polyamide imide having a strong bonding force is large. In addition, if the surface exposure ratio of the sintered metal is large, the proportion of the metal that comes into direct contact with the mating material increases, and the wear resistance is increased while the seizure resistance is reduced. The surface exposure rate is to be determined depending on the application of
When the sintered layer is composed of a single layer of metal particles, the fluctuation of the surface exposure rate due to the shaving margin becomes extremely large, and stable sliding characteristics cannot be obtained. That is, not only the sliding characteristics fluctuate greatly depending on the production lot,
If the resin wears a little during sliding, the surface exposure ratio of the sintered metal sharply increases, so that the sliding characteristics fluctuate greatly.
In such a situation, the mating material and the sliding material are often unfamiliar with each other, so that one of the materials rapidly wears out due to metal contact between the two, resulting in seizure, which is extremely undesirable. An object of the present invention is to provide a sliding material which has solved the above-mentioned disadvantages.

[0007]

SUMMARY OF THE INVENTION A sliding material according to the present invention comprises a back metal and Cu or Cu sintered on the surface of the back metal.
A sliding comprising an alloy sintered layer and a synthetic resin and a solid lubricant filled in the space between the sintered particles of the sintered layer, wherein the surfaces of the sintered layer and the filling material are machined. In the material, the sintered layer has a particle size of 30 or more laminated in two or more layers.
A metal particle having a porosity of 5 to 70% by volume and a metal layer having a porosity of 5 to 70% by volume, and a surface exposure ratio of a sintered layer on the machined surface is 95% or less; The agent consists of a total of 30 to 80% by weight of molybdenum disulfide and graphite.

Hereinafter, the configuration of the present invention will be described. The back metal is not particularly limited in type, and may be a known one. The Cu or Cu alloy sintered layer is formed by sintering pure copper, or a Cu alloy such as bronze, lead bronze, phosphor bronze, or a composite material in which powder such as FeP or Al ₂ O ₃ is dispersed in these pure copper or copper alloy. Things.

The shape of these copper-based powders is spherical or substantially spherical without sharp edges, and other irregular shapes (flaky, dendritic,
Chain, inequilateral polyhedron, etc.). In the powder mixed with irregularly shaped powder, the ratio of minor axis / major axis contained in all particles is 0.2 to
It is preferred that 0.7 is 50% or more, preferably 70% or more. When the ratio of minor diameter / major axis is more than 0.7, the effect of irregular shape powder is not exhibited. On the other hand, when the ratio of minor diameter / major axis is less than 0.2, desired average packing density is obtained. However, the effect of irregular shaped powder is not exhibited. In particular, when the irregular powder having a ratio of minor axis / major axis of 0.2 or less is 30% or less, preferably 10% or less of all the particles, the tendency of the irregular powder to densely fill the pores can be suppressed.

The size of the sintered powder, which is one of the features of the sintered layer, needs to be 30 to 200 μm in average particle diameter, preferably 50 to 200 μm, more preferably 60 to 200 μm.
１５０150 μm. In the case of irregular shaped powder, the average of the total length is 30
It is necessary to be ~ 200 μm. If the size of the sintered powder is smaller than 30 μm, if the density of the sintered body is large, it becomes difficult to impregnate the pores with a resin or a solid lubricant, and if the density of the sintered body is small, It is not preferable because the adhesive strength between Cu (alloy) particles is lowered. The porosity (volume%), which is another feature of the sintered layer, that is, the proportion of pores in the sintered body before impregnation with a resin or the like must be 5 to 70%, preferably 10 to 60%. %, More preferably 30 to 50%. If the porosity is less than 5%, the impregnation amount of the resin and the solid lubricant decreases, and the sliding characteristics such as low friction and lubricity deteriorate, and seizure easily occurs.
If it exceeds 0%, the proportion occupied by the sintered body decreases, and the strength decreases, which is not preferable.

The ratio of the sintered metal on the surface, which is another characteristic of the sintered layer, that is, the exposure rate (area%) of the sintered layer is 95%.
% Or less, preferably 85% or less, more preferably 30 to 80%. Also, depending on the application,
A high exposure rate (60 to 80%) is applied under general conditions, and a low exposure rate (40
~ 60%) is desirable. The sintering layer exposure rate has a large effect on the characteristics of the sliding material at the portion facing the mating material. Although the exposure ratio of the sintered layer was such an influential factor even in the conventional sliding material, in actuality, it varied greatly depending on the manufacturing method of the sliding material and during use. Dynamic characteristics could not be intended. However, according to the present invention, two sintered particles are used.
By laminating more than two layers, it is possible to prevent a large change in the exposure ratio of the sintered layer, and it is possible to control this to improve the sliding characteristics. If the exposure rate exceeds 95%, the effect of the solid lubricant is reduced, so it is necessary to set the exposure rate to 95% or less.

The porosity is smaller when the powder particle size is smaller, because sintering proceeds more easily. However, by using a mixed powder in which particles having a large particle diameter and a particle having a small particle diameter are mixed, the porosity is reduced even if the powder having the same particle diameter has the same average particle diameter. The porosity referred to in the present invention refers to the average porosity of the entire sintered layer (the local porosity is larger on the surface of the sintered body as can be seen from FIG. 4). .

The sintering layer exposure rate is determined by the porosity and the cutting allowance of the sintered body (see FIG. 4). The laminated structure of two or more layers, which is another feature of the sintered layer, requires that the sintered layer be cut from the surface to some extent in order to obtain a stable sintered layer exposure rate as shown in FIG. If it has a one-layer structure, the particles may fall off as a whole during sintering, and it is difficult to obtain a desired amount of cutting. Therefore, the laminated structure is limited to two or more layers.

The surface exposure ratio of the sintered layer composed of spherical powder (FIG. 5) and the sintered layer composed of irregularly shaped powder (FIG. 6) shown in FIG. 4 is almost the same as that of the latter. At 1
5-20% higher. The packing density of the powder is 4.4 to 4.8 g / cc (sintered layer volume) for the former, and 3.2 to 3.7 g / cc for the latter, and thus the low (high) of the latter (the former) is obtained. The packing density corresponds to a low (high) exposure rate. As a result, in the case of the irregular shaped powder, the surface exposure rate was 50 to 1
It becomes about 30 to 60% at 50 μm, which is the range where the seizure resistance shown in FIG. 1 is high. The characteristics of the irregularly shaped powder of FIG. 6 are as follows. Average particle size: 90 μm Minor axis / major axis ratio: less than 0.2-4% (ratio included in all particles) Minor axis / major axis ratio: 0.2-0.7-76% (included in all particles) Ratio) minor axis / major axis ratio: more than 0.7-20% (ratio included in the whole particles) In the sintered layer of FIG. 6, the average packing density of the powder is 3.5 g / cc.
It is.

The solid lubricant must contain 30 to 80% by weight, preferably 35 to 55% by weight of molybdenum disulfide and graphite. Molybdenum disulfide improves seizure resistance, and graphite improves abrasion resistance.
If the amount of the solid lubricant is less than 35% by weight, seizure or wear is likely to occur under mixed lubrication or boundary lubrication conditions,
On the other hand, when it exceeds 80% by weight, molybdenum disulfide and the like are apt to fall off. Molybdenum disulfide is preferably used under the conditions that the content in the sliding layer is 10 to 50% by weight, more preferably 15 to 35% by weight, and the average particle size is 0.5 to 25 μm. The content of graphite in the sliding layer is 2-4.
It is preferably used under the conditions of 0% by weight, more preferably 15 to 30% by weight, and an average particle size of 8 to 35 μm. The graphite may be either natural or artificial graphite, but isotropic artificial graphite is preferred from the viewpoint of abrasion resistance.

As the resin, aromatic polyimide and its modified resin, polyamideimide, polyetherimide,
Polyester imide and phenol resin are used in whole or as a main component. The amount of the resin is the balance of the solid lubricant, but is preferably in the range of 20 to 70% by weight.

As other solid lubricants, tungsten disulfide (WS ₂ ), BN, PTFE, fluororesin, P
b and the like can be further added in an amount of 3 to less than 20% by weight, preferably 5 to 20% by weight. When using these solid lubricants, it is necessary to reduce the amount of molybdenum disulfide and graphite to make the amount of resin at least as high as 20% by weight or more.

Next, an example of a method for manufacturing the above-mentioned sliding material will be described. Powder of lead bronze etc. with a particle size of -100 mesh to +200 mesh is coated on a steel plate backing to a thickness of about 300 μm.
(The number of laminations in this case is 3 layers)
Sinter at 850 ° C. This results in a porosity of about 40-50%
Is obtained. Subsequently, the back metal to which the sintered layer is bonded is immersed in a liquid in which a solid lubricant and a resin are dispersed. On this occasion,
It is important that the air in the sintered layer, which may expand during drying and cause swelling or cracking of the resin layer, be sufficiently replaced with resin. Next, the liquid is stirred with a mixer to impregnate the solid into the sintered pores. As another impregnation method, there is a method in which a liquid in which a solid lubricant and a resin are mixed is applied to a sintered layer to be impregnated. After the impregnation, drying is performed, for example, at 150 ° C. for 30 minutes. The solvent evaporates by drying, but if the viscosity of the resin is reduced by using a large amount of the solvent to facilitate the replacement of the air in the sintered layer by the resin, the evaporation of the solvent due to the drying is hindered, and the drying time is reduced. become longer. In this respect, the phenolic resin has a low viscosity (for example, 2p) even if the solid content is as high as, for example, 60%, so that the air can be sufficiently replaced and the drying time can be shortened. The drying time can be 1/6 or less of the case of polyamide imide. As a result, when a phenol resin is used, the drying line speed can be increased, and a product free of blisters and cracks can be produced.

Subsequent to drying, baking is performed, for example, at 300 ° C. for 30 minutes. Then, a sliding layer having a sintered layer exposure rate of about 70% is formed by cutting about 100 μm from the outermost surface. Further, in order to obtain a sintered body having a porosity of 50% or more, a mixture of a lead bronze powder and a graphite powder is sprayed on a backing metal, and sintered at 800 to 850 ° C. in a hydrogen stream to obtain a lead bronze. The graphite powder remaining without being sintered in the sintered alloy layer can be sucked by a dust collector. In addition, graphite powder can be used as a solid lubricant, and in this case, suction is not performed. In addition, in order to obtain a sintered body having a porosity of 50% or more, 300 to 5 particles such as melamine cyanurate are required.
A substance that sublimates at 00 ° C. can be used in combination with lead bronze. Although the example of lead bronze has been described above, other sintered metals can be similarly sintered.

[0020]

The lead bronze spherical powder having a composition of 80% Cu, 10% Sn, and 10% Pb, polyamide imide (HI, manufactured by Hitachi Chemical Co., Ltd.)
-500 or HPC-6000-26), graphite (G152 or TGP-15, manufactured by Tokai Carbon Co., Ltd.), M
Using oS ₂ (PA powder manufactured by Sumiko Lubricant Co., Ltd.)
Various sliding materials were manufactured by the above-mentioned manufacturing method, and a plate-like test piece was prepared, and was brought into linear contact with a rotating shaft on a cylindrical shaft (S45C quenching) as a mating material, and the characteristics of the test piece were comparatively evaluated. The amount of cutting was 100 μm, and the exposure rate of the sintered layer was 75 area%.

The test conditions were as follows. Abrasion resistance test Load: 10 kg Speed: 2 m / sec Lubrication: 5 cc / min Lubrication Oil type: paraffin oil Sliding distance: 1.44 × 10 ⁴ m Seizure resistance test Load: 10 kg Speed: 4 m / sec Lubrication: 0.1 cc After oiling at / min for 5 minutes, oil cut Oil type: paraffin oil The test conditions in the above-mentioned JP-B-63-37445 are quoted below for reference. Load: 250g Speed: 0.052m / sec Lubrication: Grease

Comparing these test conditions, it can be seen that the test conditions of the present invention are high load, high speed, and severe lubrication conditions. That is, the test conditions in the present invention are boundary lubrication conditions. As a result of the test, the following abrasion amount (volume abrasion amount, mm ³ ) and baking time (time from oil cut to baking-min) were obtained.

Amount of wear (mm ³ ) Baking time (min) Inventive Example A 25 wt% of MoS ₂ 0.08 55 25 wt% of graphite 50 wt% of Inventive Example B MoS ₂ 40 wt% 0.160 10 wt% of graphite 50 wt% of polyamide imide Comparative Example 1 MoS ₂ 50 wt% 0.9 50 Polyamide imide 50 wt% Comparative Example 2 Graphite 50 wt% 0.08 20 Polyamide imide 50 wt% Comparative Example 3 MoS ₂ 10 wt% 0.3 16 Graphite 10 wt% Polyamide imide 80 wt%

Further, the test was performed under the following test conditions. Seizure resistance test Load: 10 kg Speed: 4 m / sec Lubrication: Cut off mist supply after mist lubrication for 5 minutes Oil type: paraffin oil Speed: 4 m / sec Test time: 2 hours

[0025]

From the above test results, it can be seen that excellent abrasion resistance is obtained in the invention examples in which molybdenum disulfide and graphite are used in combination and the amount is increased to 50%. Subsequently, test pieces were prepared by changing the exposure rate of the sintered layer with respect to the sliding material of Inventive Example A, and the seizure resistance, wear resistance and coefficient of friction were measured. However, the test condition was that the oil type was refrigeration oil 1
A mixed oil of light oil 9 was used, lubrication was performed by lubricating the oil after cutting for 5 minutes, and other test conditions were the same as those described above.

FIG. 1 shows the results of the seizure resistance test. FIG. 1 shows that the seizure resistance rapidly deteriorates when the sintered layer exposure rate exceeds 95%. Further, it can be seen that the seizure resistance is stable when the sintering layer exposure rate is 80% or less. FIG. 2 shows the results of the wear resistance test. If the exposure ratio of the sintered layer is lower than about 10%, the resin or the solid lubricant tends to fall off, resulting in a large amount of wear. The amount is increasing. FIG. 3 shows the measurement results of the coefficient of friction. If the sintering layer exposure rate is lower than about 10%, the resin will fall off so as to collapse, resulting in a higher friction coefficient. On the other hand, if the sintering layer exposure rate is higher than about 90%, the amount of wear will increase as the amount of wear increases. The dynamic area increases, the surface pressure decreases, and the coefficient of friction decreases because the lubrication conditions approach fluid lubrication.

After observing the surface of the test piece after the baking test, the resin and the solid lubricant (hereinafter collectively referred to as “resin composition”) were applied to the surface of the bronze sintered layer and the surface of the shaft. 30% solid and solid lubricant
It was found that when the amount was more than the above, the amount of adhesion was remarkably increased as compared with the case of less than 30%. Let us consider this result.
It is presumed that heat generation on the friction surface increases under severe sliding conditions, so that the resin composition having a higher linear expansion coefficient than bronze spills out from the surface of the sintered layer and then flows and adheres to the sintered layer. Is done. If the solid lubricant is less than 30%, the bonding strength of the resin is high, so that it is difficult to create a situation in which the solid lubricant flows and adheres to the surface of the sliding agent. On the other hand, if the amount of the solid lubricant is more than 70%, since the bonding strength of the resin is reduced, abrasion occurs preferentially over the adhesion of the solid lubricant, and the wear resistance is reduced. In the case of a material in which the sintered pores are not filled with the resin, it is not possible to expect the resin composition using the difference in the coefficient of thermal expansion between the resin component and the sintered metal, and the graphite or disulfide to the sintered layer is not expected. It is considered that the abrasion resistance and seizure resistance are inferior to those of the material of the present invention because molybdenum has a weak adhesive force.

Further, the relationship between the physical properties of the solid lubricant and the improvement in wear resistance and seizure resistance as described above will be discussed. Molybdenum disulfide (MoS ₂ ) is generally a hexagonal crystal having a smaller particle size than graphite and is easily cleaved. Therefore, the molybdenum disulfide adhering to the surface of the sintered layer is sheared by friction with the shaft, cleaved, becomes fine particles, and lubricates between the shaft and the sliding material. However, due to such properties, the wear resistance of molybdenum disulfide is inferior to that of graphite (see Comparative Example 1). On the other hand, graphite is a hexagonal crystal and has the same cleavage points as molybdenum disulfide, but its hardness is higher than molybdenum disulfide and its particle size is larger, so its binding strength with resin is higher. Therefore, the wear resistance is enhanced (see Comparative Example 2). Therefore, by using molybdenum disulfide and graphite in combination, both seizure resistance and wear resistance can be improved. In particular, even when the total amount of molybdenum disulfide and graphite used is the same as the amount used alone, it is possible to improve the seizure resistance and abrasion resistance by a synergistic effect (Examples A and B and Comparative Examples 1, 2). Hereinafter, the present invention will be described in detail with reference to examples.

[0030]

EXAMPLES A sliding member was prepared by the above-described method using the composition shown in Table 1, and the abrasion resistance and seizure resistance were measured by the above-mentioned method. The physical properties of the sliding member were as follows. Sliding layer thickness: 200 μm Porosity: 35% (volume) Sintering layer exposure rate: 70% (area) Sintered metal particle diameter: 110 μm (average)

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

As is apparent from the above description, particularly from the examples, the sliding material of the present invention exhibits excellent wear resistance and seizure resistance under severe sliding conditions.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an exposure rate of a sintered layer and a baking time.

FIG. 2 is a graph showing a relationship between an exposure rate of a sintered layer and a wear amount.

FIG. 3 is a graph showing a relationship between an exposure rate of a sintered layer and a friction coefficient.

FIG. 4 is a graph showing a relationship between an exposure rate of a sintered layer and a cutting amount.

FIG. 5 is a metal micrograph showing a sintered layer composed of a spherical copper-based powder.

FIG. 6 is a metal micrograph showing a sintered layer composed of a deformed copper-based powder.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C10M 103: 04 103: 06 103: 00 103: 02 107: 38 107: 32 107: 44) C10N 10:02 10:08 10: 12 20:00 20:06 30:06 40:02 50:08 (72) Inventor Yasunori Kabuya 3-65 Midorigaoka, Toyota City, Aichi Prefecture Inside Taitoyo Kogyo Co., Ltd. (72) Inventor Keiichi Shimazaki 3 Midorigaoka, Toyota City, Aichi Prefecture Chome 65, Taitoyo Kogyo Co., Ltd. (56) References JP-B-63-37445 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16C 33/10

Claims (2)

(57) [Claims] 1. A back metal and Cu sintered on the surface of the back metal
Or a Cu alloy sintered layer, comprising a synthetic resin and a solid lubricant filled in the space between the sintered particles of the sintered layer, the surface of the sintered layer and the filling material is machined In the sliding material, the sintered layer is formed by stacking two or more layers of metal particles having a particle size of 30 to 200 μm in a volume of 5 to 70% by volume.
The sintered layer has a porosity of not more than 95%, and the surface exposure of the sintered layer on the machined surface is 95% or less, and the solid lubricant has a total amount of 30 to 80% by weight. A sliding material consisting of molybdenum disulfide and graphite and having excellent sliding characteristics under mixed lubrication or boundary lubrication conditions. 2. A back metal and Cu sintered on the surface of the back metal.
Or a Cu alloy sintered layer, comprising a synthetic resin and a solid lubricant filled in the space between the sintered particles of the sintered layer, the surface of the sintered layer and the filling material is machined In the sliding material, the sintered layer is formed by stacking two or more layers of metal particles having a particle size of 30 to 200 μm in a volume of 5 to 70% by volume.
The sintered layer has a porosity of not more than 95%, and the surface exposure of the sintered layer on the machined surface is 95% or less, and the solid lubricant has a total amount of 30 to 80% by weight. Molybdenum disulfide and graphite, 3-20% by weight of tungsten disulfide, BN, fluororesin, and P
A sliding material comprising at least one kind of b and having excellent sliding characteristics under mixed lubrication or boundary lubrication conditions.