JP3223194B2 - Sliding member - 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 member, and more particularly to a sliding member having a surface layer having a sliding surface with a mating member.

[0002]

2. Description of the Related Art Conventionally, as this kind of sliding member, there has been known a sliding bearing in which the surface layer is made of a Pb-Sn alloy (see Japanese Patent Application Laid-Open No. 56-96088).

[0003]

Problems to be Solved by the Invention This type of plain bearing is
It is applied to the journal part of the crankshaft, the large end of the connecting rod, etc. in the engine. However, in the current situation where the engine tends to be high-speed and high-power, the surface layer of the conventional plain bearing is oil There is a problem that the retention property, that is, the oil retention property is not sufficient, and the seizure resistance is poor due to poor initial conformability.

[0004] In view of the above, the present invention specifies the structure of the surface layer so that the surface layer has a sufficient oil retaining property, and the initial conformability of the surface layer is improved. An object of the present invention is to provide the sliding member having improved performance.

[0005]

According to the present invention, there is provided a sliding member having a surface layer having a sliding surface with a mating member, wherein the surface layer is formed by one of an electroplating method and a forming method via a gas phase. It is formed by using, at least one of a plurality of pyramidal projections and a plurality of truncated pyramid-shaped projections forming the sliding surface, the sliding surface, the surface layer, the surface layer thereof It is characterized by having a plurality of raised areas formed by following a plurality of projections dispersed on the lower layer surface.

[0006]

1 and 2, a sliding bearing 1 as a sliding member is applied to a journal portion of a crankshaft, a large end portion of a connecting rod and the like in an engine.
The first and second halves ₁ 1, consisting of 1 _2. Both halves 1 ₁ ,
1 ₂ have the same structure, the surface layer 3 having a substrate 2, the sliding surface 3a of the formed on the inner peripheral surface of the substrate 2 by mating members x
And Substrate 2 and the backing metal 2 _1, and its backing metal 2 ₁ is formed on the surface of the lining layer 2 _2, lining layer 2 ₂
It is formed on the surface and a barrier layer 2 ₃ for supporting the surface layer 3.

[0007] backing metal 2 ₁ is composed of rolled steel plate, the thickness thereof is determined by setting the thickness of the sliding bearing 1. Lining layer 2 ₂ Cu, Cu alloy, Al, is composed of Al-based alloy, its thickness is 50 to 500 [mu] m, usually 30
It is about 0 μm. Barrier layer 2 ₃ is made of Ni, its thickness is 0.5 to 5 [mu] m. The surface layer 3 is made of a Pb alloy and has a thickness of 5 to 50 μm, usually about 20 μm. If necessary, between the backing metal 2 ₁ and the lining layer 2 _2, Cu plating layer having a thickness of 0.5~5μm is provided.

The Pb alloy constituting the surface layer 3 is 80 to 9
It contains 0% by weight of Pb and 3 to 20% by weight of Sn, and optionally contains Cu, In, Ag, Tl, Nb, Sb, and N.
At least one selected from i, Cd, Te, Bi, Mn, Ca, and Ba is contained in an amount of 10% by weight or less.

[0009] Although Cu, Ni and Mn have a function of improving the hardness of the surface layer 3, if the content exceeds 10% by weight, the hardness becomes too high and the initial conformability decreases.
When Cu or the like is added, the hardness Hmv of the surface layer 4 is 1
It is desirable to adjust the content so as to be 5 to 25.

In, Ag, Tl, Nb, Sb, Cd, T
e, Bi, Ca, and Ba have a function of softening the surface layer 3 and improving initial conformability, but if the content exceeds 10% by weight, the strength of the surface layer 3 is reduced. When adding In or the like, it is desirable to adjust the content thereof so that the hardness Hmv of the surface layer 3 becomes 8 to 15.

The surface layer 3 is formed by an electroplating method, and a plating solution is 40 to 1 per liter.
80 g of Pb ²⁺ , 1.5 to 35 g of Sn per liter
^2+, borofluoride based plating solution comprising the following Cu ²⁺ 15 g per liter, are used as occasion demands. The temperature of the plating solution is 10 to 35 ° C., and the cathode current density is 3 to 15 A / d.
Each is set to m ^2.

[0012] The barrier layer 2 ₃ is also formed by electroplating, the plating solution, local precipitation type Ni plating solution are used.

[0013] When this forms a barrier layer 2 ₃ on the lining layer 2 ₂ using a local precipitation type Ni plating solution, a plurality of barrier layers 2 ₃ where the convex portion 4 is distributed across the surface.
When forming the surface layer 3 by electroplating such a barrier layer 2 ₃ surface, the surface layer 3 is the barrier layer 2
Macro-flat main area a to follow the surface shape of ₃
And a plurality of raised areas b corresponding to the respective projections 4 to obtain a sliding surface 3a.

FIG. 3 is an electron micrograph (× 10,000) showing the crystal structure of the Pb alloy on the sliding surface 3a. FIG.
(A), (b) shows a case where the surface layer 3 is longitudinally cut,
(A) is a micrograph (× 5,000) showing the crystal structure of the Pb alloy in the main region (a), and (b) is a raised region b
Electron micrograph (1) showing the crystal structure of the Pb alloy in FIG.
0,000 times). The surface layer 3 is made of a Pb alloy containing 8% by weight of Sn and 2% by weight of Cu. The surface layer 3 is formed on the barrier layer 2 _3, cathode current density in the electroplating process for forming the surface layer 3 was set to 6A / dm ^2.

As clearly shown in FIGS. 2 to 5, the surface layer 3
Has a plurality of pyramid-shaped projections with the apex c facing the sliding surface 3a side, in the illustrated example, a quadrangular pyramid-shaped crystal 5 of a Pb alloy to form the sliding surface 3a. Each is quadrangular pyramid-shaped crystals 5 forms a tip portion of each columnar crystal 6 extending from the barrier layer 2 _3,
Therefore, the surface layer 3 is composed of an aggregate of columnar crystals 6.

Here, if the basic plane d is defined as a plane including substantially the apex c of each pyramidal crystal 5 in the main region a,
In the raised area b protruding from the basic plane d, the diameter e is 5 μm ≦ e ≦ 50 μm, and the height f is 0.5 μm.
.Ltoreq.f.ltoreq.5 .mu.m, and a raised area b on the sliding surface 3a.
Are set to 3% ≦ g ≦ 15%, respectively.

FIG. 6 is an X-ray diffraction diagram of the Pb alloy crystal in the surface layer 3. Only the diffraction peaks of the (200) plane and the (400) plane can be recognized by the Miller index.

Here, an orientation index Oe is shown as an index representing the orientation of the crystal plane, (However, hkl is Miller index, Ihkl is (hkl)
(Ikl is the sum of Ihkl), the orientation index Oe of the (hkl) plane is 1
The closer to 00%, the more crystal planes oriented in the direction perpendicular to the (hkl) plane.

Table 1 shows the integrated intensity Ihkl and the orientation index Oe of the Pb alloy crystal on the (200) and (400) planes.

[0020]

[Table 1] From Table 1, the orientation index Oe in the (h00) plane of the Pb alloy crystal is 100%.
Crystal planes oriented in each axis direction at crystal axes a, b, c,
That is, it has the (h00) plane.

As described above, when the crystal plane is oriented in a direction orthogonal to the (h00) plane, the crystal structure of the Pb alloy is a face-centered cubic structure. 3, the seizure resistance and the abrasion resistance are improved.

FIG. 7 shows a graph of P on the sliding surface of the conventional surface layer.
5 is an electron micrograph (× 10,000) showing the crystal structure of alloy b. This surface layer comprises 8% by weight of Sn and 2% by weight of Cu.
The surface layer is formed on a Cu alloy lining layer by electroplating, and is applied to the journal portion of an engine crankshaft.

FIG. 8 is an X-ray diffraction diagram of a Pb alloy crystal in the conventional surface layer. From this figure, no orientation to a specific crystal plane is recognized. Table 2 shows the integrated intensity Ihkl and the orientation index Oe in various (hkl) planes.

[0024]

[Table 2] As is clear from FIGS. 7 and 8 and Table 2, the P
The crystal shape of the alloy b is an irregular shape in which crystal faces are randomly oriented. Due to this, the hardness of the Pb alloy is (h0
0) It is lower than that of a plane-oriented Pb alloy.

Table 3 compares the composition of the surface layer, the orientation index Oe on the (h00) plane, the crystal structure, and the structure of the raised region in various types of plain bearings. The present invention (1) corresponds to the Pb alloy shown in FIGS. 3 and 4, and the comparative example (1) corresponds to the Pb alloy shown in FIG.

[0026]

[Table 3] FIG. 9 shows the present inventions (1) to (4) and Comparative Example (1),
The result of the seizure test of (2) is shown.

The seizure test was performed by rubbing each sliding bearing against the rotating shaft, and gradually increasing the load applied to the sliding bearing. FIG. 9 shows the surface pressure when the surface layer of each slide bearing is seized.

The test conditions are as follows. Material of rotating shaft JIS S48C material subjected to nitriding treatment, rotation speed of rotating shaft 6000 rpm, lubrication temperature 120 ° C, lubrication pressure 3 kg / cm ² , load 1 kg / sec.

As is apparent from FIG. 9, the present invention (1) to (1)
(4) has better seizure resistance than the comparative examples (1) and (2). The reason why such an effect is obtained is that, in each raised area b, the vertex a side of the quadrangular pyramid-shaped crystal 5 can be preferentially worn to improve the initial conformability of the surface layer 3, and The gap between the main region a and the counterpart member x on the moving surface 3a functions as an oil reservoir and the surface area of the sliding surface 3a is enlarged by the quadrangular pyramid-shaped crystal 5, so that the surface layer 3 has sufficient oil retaining property. Due to having

FIG. 10 shows the relationship between the temperature of the surface pressure between the sliding bearing for the sliding bearing, the line h ₁ is the present invention (1)
In, also a line h ₂ corresponding respectively to the Comparative Example (1).

As is apparent from FIG. 10, the present invention (1)
Has a smaller calorific value than Comparative Example (1). This is because, as described above, the surface layer 3 has a sufficient oil retaining property and the sliding surface 3
This is because the cooling property of the oil is improved with the increase in the surface area of a. In the case of Comparative Example (1), since the temperature rises sharply, seizure occurs at a surface pressure of about 190 kg / cm ² .

FIGS. 11 and 12 (photographs taken with an electron microscope at a magnification of 10,000) show another embodiment, in which a surface layer 3 made of a Pb alloy is used.
Are formed as a plurality of truncated pyramid-shaped crystals 7 having a plurality of truncated pyramid-shaped projections with the upper bottom surface k facing the sliding surface 3a to form the sliding surface 3a
Is shown. The present invention also includes a case where the surface layer 3 has the quadrangular pyramid-shaped crystal 5 and the truncated quadrangular pyramid-shaped crystal 7.

With this configuration, the upper surface k of the truncated quadrangular pyramid crystal 7 faces the counterpart member x in at least a part of each raised region b. An oil film can be formed between the surface layer 3 and k to improve the initial conformability and stabilize the surface, and the surface layer 3 can have a sufficient oil retaining property as described above.

The present invention includes a case where the quadrangular pyramid-shaped crystal 5 and / or the truncated quadrangular pyramid-shaped crystal 7 form a part of the sliding surface 3a. In this case, the area ratio of the crystals 5 and 7 on the sliding surface 3a is set to 50% or more.

As described above, in order to obtain excellent sliding characteristics, the inclination of the quadrangular pyramidal crystal 5 and the truncated quadrangular pyramid crystal 7 becomes a problem.

Therefore, as shown in FIGS. 5 and 13, on the bottom side of the quadrangular pyramid-shaped crystal 5, the crystal 5 is projected to define an imaginary plane L along the sliding surface 3a. A straight line n passing through the vertex c of the crystal 5 and the bottom center part m forms an inclination angle θ with respect to a reference line p passing through the bottom center part m and perpendicular to the virtual plane L.
Is defined, the inclination angle θ of the quadrangular pyramidal crystal 5 is 0 ° ≦ θ.
≦ 30 ° is set. When the inclination angle θ is θ> 30 °, the oil retaining property of the surface layer 3 and the preferential wear property on the vertex c side decrease.

The tilt angle θ in the case of the truncated quadrangular pyramid crystal 7 is imaginary passing through a straight line t passing through the upper bottom center r and the lower bottom center s and a lower bottom center s as shown in FIGS. Surface L
Is defined as an angle formed by a reference line p perpendicular to. Also in this case, the inclination angle θ is set to 0 ° ≦ θ ≦ 30 °.

[0038] As another method for forming the raised region b is preliminarily formed a plurality of protrusions by chemical polishing or mechanical polishing lining layer 2 ₂ surface, a method can be cited such.

In the above embodiment, the surface layer is formed by the electroplating method.
A formation method via a gas phase such as VD, ion plating, CVD, and sputtering can be given .

The present invention is not limited to the plain bearing, but is applicable to other sliding members.

[0041]

According to the present invention, by specifying the structure of the surface layer as described above, a sliding member with improved seizure resistance of the surface layer can be provided.

[Brief description of the drawings]

FIG. 1 is an exploded plan view of a sliding bearing.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a micrograph showing a crystal structure of a Pb alloy on a sliding surface.

FIGS. 4A and 4B are micrographs showing a crystal structure of a Pb alloy when a surface layer is cut longitudinally, in which FIG. 4A corresponds to a main region, and FIG.

FIG. 5 is a schematic perspective view of a main part showing a first example of a surface layer.

FIG. 6 is an X-ray diffraction diagram of a Pb alloy crystal in the first example of the surface layer.

FIG. 7 is a micrograph showing a crystal structure of a Pb alloy on a sliding surface of a conventional example.

FIG. 8 is an X-ray diffraction diagram of a Pb alloy crystal in a conventional surface layer.

FIG. 9 is a graph showing a seizure test result.

FIG. 10 is a graph showing the relationship between the surface pressure on the slide bearing and the temperature of the slide bearing.

FIG. 11 is a schematic perspective view of a main part showing a second example of the surface layer.

FIG. 12 is a micrograph showing a crystal structure of a Pb alloy in a second example of the surface layer.

FIG. 13 is an explanatory view showing a method of measuring the inclination angle of a pyramidal crystal.

FIG. 14 is an explanatory diagram showing a method of measuring the inclination angle of a truncated quadrangular pyramid crystal.

[Explanation of symbols]

 Reference Signs List 1 sliding bearing (sliding member) 3 surface layer 3a sliding surface 5 quadrangular pyramid-shaped crystal (pyramidal projection) 7 quadrangular truncated pyramid (truncated pyramidal projection) b raised area x mating member

Continuation of the front page (56) References JP-A-51-141703 (JP, A) JP-A-59-13093 (JP, A) JP-B-7-9079 (JP, B2) Patent 2741437 (JP, B2) Patent 2519556 (JP, B2) Patent 2519557 (JP, B2) Patent 2657335 (JP, B2) Patent 2704800 (JP, B2) Patent 2645767 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C25D 7/00 F16C 33/10 F16C 33/12

Claims (1)

(57) [Claims] 1. A sliding member having a surface layer (3) having a sliding surface (3a) with a mating member (x), wherein said surface layer (3) is formed by an electroplating method and a gas phase. Formed using one of the methods, wherein the sliding surface (3
a) has at least one of a plurality of pyramidal projections (5) and a plurality of truncated pyramidal projections (7), and the sliding surface (3a) is formed by the surface layer (3). 3) a plurality of projections (4) dispersed on the surface of the lower layer (2 ₂ , 2 ₃ )
A sliding member comprising a plurality of raised areas (b) formed by following the above.