JP2002147459A - Sliding bearing with overlay layer quality-improved - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding bearing with the improved abrasion resistance, seizure resistance, and fatigue resistance. SOLUTION: This sliding bearing is provided with a back plate layer 1, a bearing alloy layer 2 provided on the back plate layer 1, and an overlay layer 3 stacked on the bearing alloy layer 2 and becoming the surface layer. It is so set that the overlay layer 3 is formed with recesses with the maximum height within a range from 2 to 10 μm at mean intervals between the recesses within a range from 0.01 to 0.08 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding bearing used as a bearing for an internal combustion engine of an automobile, a ship, an agricultural machine, a construction machine, and the like, and in particular, has excellent fatigue resistance, wear resistance, and seizure resistance. It relates to a sliding bearing.

[0002]

2. Description of the Related Art Conventionally, a high-load plain bearing for an internal combustion engine is prepared by wet-treating a soft metal such as a lead-based alloy or Sn directly or through an intermediate plating layer on the surface of a copper-based bearing alloy layer provided on a steel backing. It is coated by a plating method and is widely used for connecting rod bearings and the like. In addition, an aluminum-based bearing alloy layer such as an AL-Sn-based or AL-Sn-Si-based material partially coated with an overlay layer is also used in place of the copper-based bearing alloy. The overlay layer that performs this plating is familiar,
It is provided to enhance seizure resistance, foreign matter embedding property, corrosion resistance, and the like, and further requires fatigue resistance and wear resistance as surface sliding characteristics.

[0003] Usually, a copper-based bearing alloy is made of Cu-Pb-Sn.
100-300 by casting and sintering the system alloy on steel
layered on a steel backing metal with a thickness of
-Sn-Cu, Pb-Sn-In, Pb-Sn-Cu-
It is coated with an In-based alloy of about 20 μm, and recently, an Sn-Ag-based alloy has been studied.

[0004]

Recently, gasoline engines and diesel engines, particularly those used in passenger cars and the like, rotate at high speeds, and therefore, engine bearings are required to have higher seizure resistance, wear resistance and fatigue resistance. Improvement is required. As described above, the properties required for the overlay layer are contradictory to properties requiring softness in the surface layer, such as foreign matter embedding property and initial conformability, and properties requiring hardness and strength such as wear resistance and fatigue resistance. Characteristics are required.

For this reason, in the Pb-based overlay layer, Cu
To increase the strength of the plating material by adding a few percent by weight, and to suppress the decrease in hardness at high temperatures by adding In, improve the wettability with engine oil, and form an oil film. As a result, the wear resistance and seizure resistance were improved, and the overall overlay film was balanced.

There is a limit in examining the material components alone.
Recently, as shown in, for example, JP-A-7-259858 and JP-A-7-259959, the machined surface of the surface is aligned in parallel with the rotational sliding direction, and the pitch of the annular protrusions and the height of the peaks are adjusted. And by changing the plating conditions of the Pb-based overlay layer as shown in JP-A-5-25689 or JP-A-5-9789, in which an oil film maintaining function is imparted to the sliding surface. The crystal orientation is increased, pyramid-shaped projections are deposited on the surface, the hardness is increased, and an oil film generating function is imparted to the sliding surface by unevenness, thereby improving seizure resistance and wear resistance.

However, the annular projection has directionality and is continuous along the entire circumference in the circumferential direction, and the trough of the pyramidal projection is connected to the periphery. Therefore, in the sliding portion with the shaft, the recess forming an oil reservoir is not closed, and the oil film pressure generated between the rotating partner shaft and the slide bearing is not confined and leaks, and the oil film pressure is reliably held. For this reason, in a bearing of a high-power engine in which a high surface pressure is applied, the oil film thickness becomes thin, and seizure or wear may not be prevented.

Further, when an annular projection is formed by machining to hold an oil film, the hardness of the overlay layer is usually as soft as Hv10 to 15 and the plating surface cannot be machined directly. Although a processing line is formed and plated about 20 μm from above, the annular projection is buried due to the smoothing effect of the wet plating treatment, and the original effect may not be exhibited in some cases.

The present invention has been made in view of the above, and by forming a fine crater-like concave portion directly in an overlay layer and forming a closed space on a bearing sliding surface with a shaft, It is an object of the present invention to provide a sliding bearing in which an oil sump function is imparted to a surface, an oil film generated during operation is thickened, and wear resistance, seizure resistance, and fatigue resistance are improved.

[0010]

SUMMARY OF THE INVENTION A plain bearing according to the present invention comprises:
A back metal layer, a bearing alloy layer represented by a copper alloy layer provided on the back metal layer, and an overlay layer laminated on the bearing alloy layer and serving as a surface layer, wherein the overlay layer has an average Concave portions having an interval of 0.01 to 0.08 mm and a maximum height of 2 to 10 μm are formed on the surface.

Further, the recesses formed on the surface of the overlay layer are formed by spraying hard particles having an average particle diameter of 20 to 100 μm onto the surface of the overlay layer.

Further, the overlay layer is made of a Pb alloy and Sn or a Sn alloy, and has a thickness in the range of 5 to 30 μm.

[0013]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view of a plain bearing according to the present invention.

As shown in FIG. 1, this plain bearing includes a back metal layer 1, a copper alloy layer 2 provided on the back metal layer 1, an overlay layer 3 laminated on the copper alloy layer 2 and serving as a surface layer. It is formed with. In the overlay layer 3, a predetermined concave portion 4 is formed by performing a specific blasting process described later. This recess 4
A closed space can be formed in the bearing sliding surface, thereby providing an oil sump function to the surface, increasing the oil film generated during operation, and improving the wear resistance and seizure resistance of the overlay layer 3.
Fatigue resistance can be improved.

Usually, in the sand blasting or the shot blasting, the blast hard particles are buried in the overlay layer, and the plating layer is lost or peeled off, so that the blast effect is not exhibited. For example, in shot peening, a steel ball having a diameter of 0.6 to 0.9 mm is sprayed at a speed of 40 to 60 m per second, but under such conditions, the overlay layer disappears instantaneously.

Therefore, the blast treatment of the overlay layer on the plain bearing of the present invention is carried out by using an average particle diameter of 20 to 20 which is considerably smaller than the average particle diameter of the hard particles used in the ordinary blast treatment.
A blast process of spraying 100 μm hard particles onto the surface of the overlay layer 3 is performed.

When the average particle diameter of the hard particles is less than 20 μm, the hard particles easily penetrate the overlay surface and are easily embedded, and consequently the sliding performance decreases. If the diameter exceeds 100 μm, the oil pool becomes shallow, and the oil pool effect is not exhibited.

Hard particles used include iron-based materials such as steel shot and steel grit, and ceramic-based materials include alundum, glass particles, fused silica particles, and silica sand. Walnut hulls or the like may be used as an organic material. The particle spraying speed is such that the average interval between the concave portions is 1
The particle size is adjusted according to the specific gravity of the particles and the average particle size so that the particle size is 0 to 80 μm and the maximum height is 2 to 10 μm.

The average distance between the recesses is JIS B0601-
The average interval Sm of the irregularities defined in 1994 was used. Sm
Is defined as extracting a reference length from a roughness curve, obtaining an average line length between adjacent local peaks in the extracted portion, and arithmetically averaging the intervals between the multiple local peaks. Similarly, the maximum height was Ry defined by JIS.

In the plain bearing of the present invention, in order to clarify these upper and lower limits, the average interval Sm of the unevenness and the maximum height Ry are set.
Was measured three times with the stylus drive speed set to 0.1 mm per second, the reference length set to 2.5 mm, and the cutoff set to 0.8 mm, and the average value was determined. Maximum height Ry is 2μm
If it is less than 30, the oil film holding function is hard to act, the surface temperature of the bearing increases, and the seizure resistance does not improve.

On the other hand, if the average distance Sm between the concave portions exceeds 80 μm, the blocking property of the oil pool is weakened, the oil film pressure generated during operation of the engine cannot be maintained, and the wear resistance and seizure resistance cannot be improved.

When the maximum height Ry exceeds 10 μm, cavitation erosion occurs around the oil pool, and the phenomenon that the overlay is partially peeled is likely to occur. If the average distance Sm between the concave portions is less than 10 μm, the friction coefficient increases due to the viscous resistance of the oil, and the seizure resistance does not improve.

As for the hard particle shape of the blast used, a spherical shape is preferable. Hard particles having sharp edges are more likely to be buried or stabbed in the surface overlay layer, and to cause a digging phenomenon during blasting, which tends to peel off the overlay film.
When spherical particles are used, the concave portion that becomes an oil reservoir becomes spherical, so that the surface oil of the oil does not easily run out of oil due to the surface tension, the oil film is easily maintained, and it is effective in improving wear resistance and seizure resistance. . The circularity coefficient was measured by image processing, and it was found that favorable sliding characteristics were obtained when the spherical shape was 0.6 or more.

In the bearing alloy layer 2 typified by the base copper alloy layer in the present invention, when the engine is running, the overlay is worn out and the bearing alloy is exposed due to foreign matter entering the sliding surface or running out of oil. Even in such a case, a bearing alloy having excellent sliding characteristics, such as a Cu-Pb-based, Cu-Pb-Sn-based,
A Cu-Ag-Sn system or the like is used.

In addition, as an element for improving corrosion resistance, such as Ni, Mo, W, nitride, etc. as additives for improving wear resistance and seizure resistance.
Hard particles such as sulfides, oxides and carbides may be added to the copper alloy.

As described above, the overlay layer 3 in the present invention is required to have conformability, foreign matter burying property, seizure resistance, abrasion resistance, fatigue resistance and the like as required characteristics, and 5 μm to 30 μm. Use a soft overlay with a thickness of If the thickness of the overlay layer 3 is less than 5 μm, it is not possible to bury the foundry sand, cast iron powder chips and abrasion powder present in the engine oil, and there is a possibility that the overlay layer disappears due to abrasion. And seizure easily occur. Thickness 3
If it exceeds 0 μm, it is easy to wear, and the effect of increasing the thickness is lost, and the fatigue resistance is also deteriorated.

As a component of the overlay layer 3, Pb-S
n-based, Pb-Sn-Cu-based, Pb-In-Cu-based, Pb
-Sn-In-Cu system, Sn-Ag system, Sn-In-A
g-based, Sn or the like is used. Further, hard particles such as Mo, W, nitrides, sulfides, oxides, and carbides may be added to the overlay layer 3 as additives for improving wear resistance and seizure resistance.

Next, a description will be given of a test for confirming and evaluating the above-described performance of the sliding bearing of the present invention, which was performed using a sample product.

A back metal 1 made of steel having a carbon amount of 0.12% by weight and having a thickness of 1.2 mm, and Cu-23w% by weight Pb-1.5% by weight Sn produced on the back metal 1 by a casting method Was pressed into a half bearing shape, cut to a predetermined size and finished to obtain an evaluation test sample of the copper alloy layer 2 having a thickness of 0.3 mm.

After degreasing and pickling on the copper alloy layer 2,
Approximately 1μ of Ni plating in nickel sulfate bath to improve adhesion
After plating, the inner surface of the bearing is uniformly coated with
Plating was performed at a thickness of 0 μm. One of these two types of overlay plating is Pb-10% by weight Sn-
2 wt% Cu, one was Pb-10 wt% Sn-10 wt% In-3 wt% Cu.

Further, the surface of the overlay layer 3 is subjected to a blasting treatment using usually random particles as hard particles and fused silica particles as substantially spherical hard particles to form a closed concave portion on the surface. Particle size is 5
It was 0.46 when the circularity coefficient was measured at 0 μm. The average particle size of the fused silica particles is 15, 50, 80, 1
Four types of particles of 50 μm were used, and the circularity coefficient of the particles was in the range of 0.62 to 0.79. In the hard particles having each average particle diameter, particles exceeding 2.5 times the particle diameter and particles not more than 1/3 of the particle diameter were cut in advance.

The blast conditions vary depending on the particle size. For example, in Example 1-1 (see Table 4), Pb-10% by weight Sn was used.
Average particle size 5 on overlay plating of -2% by weight Cu component
0 μm of fused silica particles were collected at a flow rate of 120 m / sec with a distance of 300 mm from the sample to the blast gun.
Sprayed for seconds.

FIG. 2 shows a typical surface condition of a plain bearing according to the present invention, and FIG. 3 shows a surface condition of a conventional plated plain bearing without blasting.

By changing the particle size and the blast conditions as described above, samples having different maximum heights Ry and average intervals Sm were manufactured, and the above-mentioned performance confirmation test of the copper-based plain bearing of the present invention was carried out. The evaluation was performed under the test conditions.

Evaluation test of wear resistance See Table 1. Bearing inner diameter size φ50 mm The amount of wear was determined by measuring the thickness of the central part of the bearing before and after the test, and taking the difference between before and after the test.

Load resistance evaluation test See Table 2 Bearing inner diameter size φ50mm Check the load resistance by checking the bearing surface every 10 hours.
The time between the time when the overlay disappeared by 2/3 or more of the whole or the time when the underlying copper alloy was peeled or cracked and the time before the time was defined as the durability time (fatigue resistance) (N
= Average time of 3).

Evaluation Test of Seizure Resistance See Table 3 Bearing inner diameter size φ50 mm For seizure resistance, the load was linearly increased, seizure was judged by seizure judgment, and the load at that time was defined as seizure load (N =
2).

Table 4 shows Examples 1-1 to 3 prepared.
9 summarizes the results of evaluation tests performed on the sample No. 1 and the samples of Reference Comparative Examples 1 to 8.

The overall evaluation in the right column indicates that, when Comparative Example 1 without blasting was significantly superior in all of the wear amount showing the wear resistance, the seizure load showing the seizure resistance, and the fatigue resistance, it was very good. Good ◎, good when the wear amount, seizure load, and fatigue resistance are all excellent, and a little bad △ when any of the wear amount, seizure load, and fatigue resistance are bad, △,
If at least one of the seizure load and fatigue resistance is significantly poor, it is evaluated as bad.

As shown in Table 4, in Examples 1-1 to 3, the spray particles used were 20 to 100 μm, and the overall evaluation was ◎ or ○, and Comparative Examples 2 to 8 were , Spray particles used are less than 20 μm or 100 μm
And the overall rating is △ or?.

In Examples 1-1 to 3, the average distance Sm is in the range of 0.015 to 0.080 mm.
Further, the maximum height Ry is in the range of 3 to 9 μm, and the overall evaluation is all ◎ or ○. On the other hand, in Comparative Examples 2 to 8, the average interval Sm was less than 0.015 or 0.08.
0mm or maximum height Ry is less than 2 or 10μ
m, and the overall rating is △ or?.

Therefore, the spray particles on the surface of the overlay layer 3 are best in the range of 20 to 100 μm, and the unevenness is in the range of 0.01 to 0.08 mm in average distance Sm and the maximum height Ry.
It can be seen that the range of 2 to 10 μm is best.

[0044]

The sliding bearing of the present invention comprises a back metal layer, a bearing alloy layer provided on the back metal layer, and an overlay layer laminated on the bearing alloy layer and serving as a surface layer, wherein the overlay layer is , Average distance between concaves is 0.01 to 0.08 mm
, And a fine crater-shaped recess having a maximum height in the range of 2 to 10 μm is formed on the surface, so that an oil reservoir function is provided on the surface, and an oil film generated during operation is thickened. Abrasion, seizure resistance and fatigue resistance can be improved.

The concave portions formed in a fine crater shape on the surface of the overlay layer have an average particle size of 20 to 1
Since the hard particles having a thickness of 00 μm are sprayed on the surface of the overlay layer, a concave portion having an accurate oil pool function can be formed on the surface of the overlay layer, and the wear resistance, seizure resistance, and fatigue resistance can be improved. Can be improved.

Further, when the hard particles are more preferably formed into a spherical shape having a circularity coefficient of 0.6 or more, it is possible to form an accurate concave portion on the surface of the overlay layer, and to obtain abrasion resistance, seizure resistance, Fatigue resistance can be improved.

Further, since the overlay layer is made of Pb alloy and Sn or Sn alloy and has a thickness in the range of 5 to 30 μm, an accurate concave portion can be formed, and abrasion resistance and seizure resistance are obtained. , Fatigue resistance can be improved.

Friction test conditions

[Table 1]

Load resistance test conditions

[Table 2]

Baking test conditions

[Table 3]

[0051]

[Table 4]

[Brief description of the drawings]

FIG. 1 shows a sectional view of a plain bearing according to the present invention.

FIG. 2 shows a surface condition of a sliding bearing according to an embodiment of the present invention.

FIG. 3 shows the surface state of a conventional plated copper-based plain bearing without blast treatment.

[Explanation of symbols]

 Reference Signs List 1 back metal layer 2 bearing alloy layer 3 overlay layer 4 concave

Claims (3)

[Claims] 1. A backing metal layer, a bearing alloy layer provided on the backing metal layer, and an overlay layer laminated on the bearing alloy layer and serving as a surface layer, wherein the overlay layer has an average distance between concave portions. A sliding bearing, wherein a fine crater-shaped recess having a range of 0.01 to 0.08 mm and a maximum height of 2 to 10 μm is formed on the surface. 2. The sliding bearing according to claim 1, wherein the concave portions formed on the surface of the overlay layer are formed by spraying hard particles having an average particle diameter of 20 to 100 μm on the surface of the overlay layer. 3. The method according to claim 1, wherein the overlay layer is a Pb alloy having a thickness in the range of 5 to 30 μm, Sn or Sn alloy, and the bearing alloy layer is a copper alloy layer. The slide bearing described in 1.