JPH0510334A - Sliding member - Google Patents

Abstract

PURPOSE:To provide a sliding bearing having a surface layer with excellent seizure resistance. CONSTITUTION:The sliding face 4a of a surface layer 4 is formed with rectangular conical crystals 5 of Pb alloy with their vertexes (a) faced to the sliding face 4a side. The rectangular conical crystals 5 have protruded pieces 8 on their slant faces 7. The oil colliding with the protruded pieces 8 within the oil flowing to the vertexes (a) from the bottom sides of the rectangular conical crystals 5 is pushed back to the bottom sides of the rectangular conical crystals 5 and is temporarily retained there. The surface area of the sliding face 4a is expanded, the surface layer 4 has a sufficient oil retaining property via the oil retention effect, the vertexes (a) of the rectangular conical crystals 5 are preferentially abraded, and the initial conformability can be improved.

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 type of sliding member, a slide bearing having the surface layer made of a Pb-Sn alloy has been known (see Japanese Patent Laid-Open No. 56-96088).

[0003]

This type of sliding bearing is
It is applied to the crank part of the crankshaft of the engine, the large end of the connecting rod, etc.However, under the current circumstances where the engine tends to be high speed and high output, the surface layer of the conventional slide bearing is made of the oil. There is a problem that seizure resistance is poor because the retention property, that is, the oil retention property is not sufficient and the initial conformability is poor.

In view of the above, the present invention provides the surface layer with a sufficient oil retaining property by specifying the structure of the surface layer, and also improves the initial conformability of the surface layer, which results in seizure resistance of the surface layer. An object of the present invention is to provide the sliding member having improved properties.

[0005]

According to the present invention, in a sliding member having a surface layer having a sliding surface with a mating member, the surface layer slides at an apex to form the sliding surface. It has at least one of a plurality of pyramid-shaped projections directed to the surface side and a plurality of truncated pyramidal projections whose upper bottom surface is directed to the sliding surface side, and the projection temporarily retains oil on the bottom side thereof. It is characterized by having a protruding piece.

[0006]

1 and 2, a sliding bearing 1 as a sliding member is applied to a journal portion of a crankshaft in an engine, a large end portion of a connecting rod, and the like.
It consists of first and second halves 1 ₁ and 1 ₂ . Both halves 1 ₁ ,
1 and ₂ have the same structure and have a back metal 2, a lining layer 3 formed on the inner peripheral surface of the back metal 2, and a sliding surface 4a formed on the surface of the lining layer 3 with the mating member x. And a surface layer 4. A Cu plating layer is provided between the back metal 2 and the lining layer 3, and the lining layer 3 and the surface layer 4 are also provided.
A Ni-plated barrier layer is provided between them as required.

The back metal 2 is made of rolled steel plate, and its thickness is determined by the set thickness of the plain bearing 1. The lining layer 3 is made of Cu, a Cu-based alloy, Al, an Al-based alloy, or the like, and has a thickness of 50 to 500 μm, usually 300 μm.
It is about m. The surface layer 4 is composed of a Pb alloy and has a thickness of 5 to 50 μm, usually about 20 μm. The Pb alloy forming the surface layer 4 contains 80 to 90% by weight of Pb and 3 to 20% by weight of Sn, and if necessary, Cu,
In, Ag, Tl, Nb, Sb, Ni, Cd, Te, B
Contains at least 10% by weight of at least one selected from i, Mn, Ca, and Ba.

Cu, Ni, and Mn have the function of improving the hardness of the surface layer 4, but if the content thereof exceeds 10% by weight, the hardness becomes too high and the initial conformability deteriorates.
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 4 to improve initial conformability, but when the content thereof exceeds 10% by weight, the strength of the surface layer 4 decreases. When In or the like is added, it is desirable to adjust the content so that the hardness Hmv of the surface layer 4 becomes 8 to 15.

The surface layer 4 is formed by an electroplating method, and the plating liquid is 40 to 1 per liter.
80 g Pb ²⁺ , 1.5-35 g 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 5 to 50 ° C, and the cathode current density is 3 to 15 A / dm.
Set to ² respectively.

FIG. 3 is an electron micrograph (× 10,000) showing the crystal structure of the Pb alloy on the sliding surface 4a. Figure 4
Is a partially enlarged electron micrograph of FIG. 3, taken at a magnification of 5,000 times. The surface layer 4 is made of a Pb alloy containing 8 wt% Sn and 2 wt% Cu. The surface layer 4 was formed on the Cu alloy lining layer 3, and the cathode current density in the electroplating treatment when forming the surface layer 4 was set to 6 to 10 A / dm ² .

As clearly shown in FIGS. 3 to 5, the surface layer 4
Has a plurality of pyramidal projections with the apex a directed toward the sliding surface 4a, in the illustrated example, a quadrangular pyramidal crystal 5 of Pb alloy to form the sliding surface 4a. Each quadrangular pyramid-shaped crystal 5 forms the tip of each columnar crystal 6 extending from the lining layer 3, and therefore the surface layer 4 is composed of an aggregate of columnar crystals 6.

As described above, the sliding surface 4a is formed into a quadrangular pyramidal crystal 5.
If formed, the apex a side of the quadrangular pyramidal crystal 5 can be preferentially worn to improve the initial conformability of the surface layer 4, and the quadrangular pyramidal crystal 5 allows the surface area of the sliding surface 4a to be improved. Can be expanded to give the surface layer 4 sufficient oil retention. In this case, the preferential wear on the apex side ends at the beginning of sliding and the flat surface (corresponding to the upper bottom surface of the truncated pyramid)
Since the oil film always exists between the flat surface and the mating member, the abrasion of the sliding surface 4a after that is extremely slow.

As shown in FIG. 6, some (or all) of the quadrangular pyramidal crystals 5 have a projecting piece 8 on the slope 7.

With this structure, when the oil that has flowed into the valley 9 between the two adjacent quadrangular pyramidal crystals 5 flows out toward the apex a, a part of the oil is projected as shown by the arrow.
The colliding oil is collided with the crystal 5 by the projecting piece 8.
Is pushed back to the bottom side, that is, the valley bottom side in the illustrated example, and temporarily stays there. This also improves the oil retaining property of the surface layer 4. In order to obtain this retention effect, when the base length of the quadrangular pyramidal crystal 5 is b, the height is c, the protruding length of the protruding piece 8 from the apex a is d, and the height is e, , (D
/ B) × 100 is preferably 50% or less, and (e / c) ×
100 is preferably 50% or more.

FIG. 7 shows the relationship between the abundance of the quadrangular pyramidal crystals 5 having the protruding pieces 8 in the surface layer 4 and the seizure-occurring surface pressure.

The seizure test was carried out by rubbing each sliding bearing on the rotary shaft and gradually increasing the load applied to the sliding bearing. FIG. 7 shows the surface pressure when seizure occurs on the surface layer of each plain bearing.

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

As is apparent from FIG. 7, the abundance of the quadrangular pyramidal crystals 5 having the protruding pieces 8 is 10 ⁵ pieces / mm ² or more,
A value of 10 ⁶ pieces / mm ² or less is suitable. This abundance is 10 ⁵
Is less than number / mm ^2, the oil retention effect of improving the protruding piece 8 is diminished, whereas, 10 exceeds ^six / mm ^2, oil flow is hindered by the protruding piece 8 cooling of oil is reduced.

As shown in FIGS. 3, 5 and 8, the slopes 7 of adjacent quadrangular pyramidal crystals 5 are connected by, for example, a pair of blocking pieces 10. The blocking pieces 10 are formed on both crystals 5 as shown by the arrows.
An oil reservoir 11 for temporarily retaining oil is formed between them. Further, the blocking piece 10 also has a function of changing the direction of the flow of the oil that collides with the blocking piece 10 as shown by an arrow to temporarily retain the oil between the crystals 5. The oil retaining property of the surface layer 4 can be improved also by such a blocking piece 10.

FIG. 9 shows that the blocking piece 10 is provided on the surface layer 4.
The relationship between the abundance and the surface pressure of seizure is shown. The seizure test was performed by the same method and conditions as described above.

As is apparent from FIG. 9, it is appropriate that the amount of the blocking pieces 10 is 10 ⁴ pieces / mm ² or more and 10 ⁶ pieces / mm ² or less. If the existing amount is less than 10 ⁴ pieces / mm ² , the oil retaining effect of the blocking piece 10 is diminished, while 10
^{When the} number exceeds ⁶ pieces / mm ² , the blocking piece 10 impedes the flow of oil and reduces the cooling performance of oil.

FIG. 10 is an X-ray diffraction diagram of the Pb alloy crystal in the surface layer 4, and only the diffraction peaks of the (200) plane and the (400) plane are recognized by the Miller index.

Here, the orientation index Oe is an index representing the orientation of the crystal plane, (However, hkl is Miller index, Ihkl is (hkl)
If the integral intensity of the surface, ΣIhkl, is defined as the sum of Ihkl), the orientation index Oe of the (hkl) surface is 1
The closer it is to 00%, the more crystal planes are oriented in the direction orthogonal to the (hkl) plane.

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

[0026]

[Table 1]

From Table 1, the orientation index Oe on the (h00) plane of the Pb alloy crystal is 100%, and therefore Pb
The alloy crystal has crystal planes oriented in the respective axial directions on the crystal axes a, b, and c, that is, the (h00) plane.

When the crystal plane is oriented in the direction orthogonal to the (h00) plane as described above, the crystal structure of the Pb alloy is a face-centered cubic structure, so that the atomic density in the orientation direction becomes high, so that the surface layer The hardness of No. 4 is increased and its seizure resistance is improved.

FIG. 11 is an electron micrograph (10,000 times) showing the crystal structure of the Pb alloy on the sliding surface of the conventional surface layer.
Is. This surface layer consists of 8 wt% Sn and 2 wt% C.
The surface layer is made of Pb alloy containing u and is formed on the Cu alloy lining layer by electroplating, and is applied to the journal portion of the engine crankshaft.

FIG. 12 is an X-ray diffraction diagram of the Pb alloy crystal in the surface layer of the conventional example. Orientation to a specific crystal plane is not recognized from this figure. Table 2 shows the integrated intensity Ihkl and the orientation index Oe in various (hkl) planes.

[0031]

[Table 2]

As is apparent from FIGS. 11 and 12 and Table 2, the crystal shape of the conventional Pb alloy is an indefinite shape in which the crystal planes are randomly oriented, and the surface layer is composed of an aggregate of granular crystals. . Due to this, the hardness of the surface layer is
It is lower than that of the (00) plane oriented surface layer.

Table 3 compares the composition of the surface layer, the properties of the sliding surface, etc. of various slide bearings. The present invention (1) corresponds to the Pb alloy (FIG. 3) in the present invention, and the comparative example (1) corresponds to the Pb alloy (FIG. 11) in the conventional example. The seizure test was performed by the same method and conditions as described above.

[0034]

[Table 3]

From Table 3, it is clear that the inventions (1) to (4) have excellent seizure resistance as compared with Comparative Examples (1) and (2). The inventions (1) and (2) are shown in FIG.
The inventions (3) and (4) are shown in FIG.

As shown in FIG. 13, in the present invention, the surface layer 4 made of Pb alloy has a plurality of truncated pyramid shapes with the upper bottom surface f facing the sliding surface 4a so as to form the sliding surface 4a. The projections, in the illustrated example, include the case where only the quadrangular truncated pyramid-shaped crystal 12 is included and the case where the quadrangular pyramid-shaped crystal 5 and the quadrangular-pyramidal truncated crystal 12 are included, and in these cases, the sliding characteristics similar to the above are obtained. . In this configuration, since at least a part of the sliding surface 4a is formed from the upper bottom surface f of the truncated pyramid crystal 12, an oil film is formed between the mating member and the upper bottom surface f from the initial stage of sliding. It is possible to improve the initial conformability and stabilize it.

The present invention also includes a crystal in which the quadrangular pyramidal crystal 5 and / or the quadrangular pyramid crystal 12 forms a part of the sliding surface 4a. In this case, the area ratio of the pyramidal crystals 5 on the sliding surface 4a is set to 50% or more. The balance is granular crystals of Pb alloy.

As described above, in order to obtain excellent sliding characteristics, the inclination of the quadrangular pyramidal crystal 5 and the truncated quadrangular pyramid crystal 12 poses a problem.

Therefore, as shown in FIGS. 5 and 14, on the bottom surface side of the quadrangular pyramidal crystal 5, the crystal 5 is projected to define an imaginary plane G along the sliding surface 4a. A straight line k passing through the apex a of the crystal 5 and the center part h of the bottom face forms an inclination angle θ with respect to a reference line m passing through the center part h of the bottom face and perpendicular to the virtual plane G.
, The inclination angle θ of the quadrangular pyramidal crystal 5 is 0 ° ≦ θ
It is set to ≦ 30 °. When the inclination angle θ is θ> 30 °, the oil retaining property of the surface layer 4 and the preferential wear property on the apex side are deteriorated.

The tilt angle θ in the case of the truncated pyramidal crystal 12 is
As shown in FIGS. 13 and 15, it is defined as an angle formed by a straight line r passing through the upper bottom central portion n and the lower bottom central portion p and a reference line m passing through the lower bottom central portion p and perpendicular to the virtual plane G. Also in this case, the inclination angle θ is set to 0 ° ≦ θ ≦ 30 °.

Although the surface layer is formed by the electroplating method in the above-mentioned embodiment, the other surface layer forming method is P.
Examples of the formation method include a vapor phase method such as VD, ion plating, CVD, and sputtering. Further, in forming pyramidal protrusions on the sliding surface, it is possible to apply chemical etching, electric etching, vapor phase etching (bombarding treatment) or other etching methods, or mechanical processing such as transfer or cutting. is there.

The present invention is not limited to sliding bearings, but can be applied to other sliding members.

[0043]

According to the present invention, by specifying the structure of the surface layer as described above, it is possible to provide a sliding member having improved seizure resistance of the surface layer.

[Brief description of drawings]

FIG. 1 is an exploded plan view of a plain 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.

FIG. 4 is an enlarged micrograph of a main part of FIG.

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

6 is a sectional view taken along line 6-6 of FIG.

FIG. 7 is a graph showing the relationship between the abundance of quadrangular pyramidal crystals having protruding pieces and the surface pressure at which seizure occurs.

8 is a sectional view taken along line 8-8 of FIG.

FIG. 9 is a graph showing the relationship between the amount of blocking pieces present and the surface pressure at which seizure occurs.

FIG. 10 is an X-ray diffraction diagram of a Pb alloy crystal in the first example of the surface layer.

FIG. 11 is a micrograph showing a crystal structure of a Pb alloy on a sliding surface of a conventional example.

FIG. 12 is an X-ray diffraction diagram of a Pb alloy crystal in a surface layer of a conventional example.

FIG. 13 is a schematic perspective view of a main portion showing a second example of the surface layer.

FIG. 14 is an explanatory diagram showing a method for measuring a tilt angle of a pyramidal crystal.

FIG. 15 is an explanatory diagram showing a method of measuring a tilt angle of a truncated pyramid crystal.

[Explanation of symbols]

1 Sliding bearing (sliding member) 4 surface layer 4a Sliding surface 5 Pyramidal crystals (pyramidal protrusions) 8 protruding piece 10 Blocking piece 12 Square pyramid-shaped crystals (pyramidal protrusions) a vertex f Upper bottom surface x Opponent member

Claims (2)

[Claims] 1. A sliding member comprising a surface layer (4) having a sliding surface (4a) with a mating member (x), wherein the surface layer (4) forms the sliding surface (4a). In order to do so, a plurality of pyramid-shaped projections (5) with their vertices (a) facing the sliding surface side and a plurality of truncated pyramidal projections (12) with their upper bottom surface (f) facing the sliding surface (4a) side. The sliding member having at least one of the above, and the projection (5, 12) is provided with a protruding piece (8) for temporarily retaining oil on the bottom side thereof. 2. A sliding member comprising a surface layer (4) having a sliding surface (4a) with a mating member (x), wherein the surface layer (4) forms the sliding surface (4a). In order to do so, a plurality of pyramid-shaped projections (5) with their vertices (a) facing the sliding surface side and a plurality of truncated pyramidal projections (12) with their upper bottom surface (f) facing the sliding surface (4a) side. And a pair of adjacent projections (5, 12) are connected by a blocking piece (10) for temporarily retaining oil between them. Element.