JP3217596B2 - Plain bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plain bearing. More specifically, the present invention relates to a bearing alloy layer called a lining such as kelmet or aluminum alloy.
The present invention relates to a sliding bearing formed of a Pb alloy plating layer with or without a barrier layer such as Ni plating and having an overlay layer exhibiting conformability. In particular, the present invention improves bearing performance by controlling the crystal structure of the overlay.

[0002]

2. Description of the Related Art The above-mentioned plain bearing is mainly used for a journal portion of a crankshaft of an internal combustion engine and a large end portion of a connecting rod.

[0003] The overlay is mainly produced by electroplating, but when the component system of the Pb alloy becomes a multi-component system such as ternary or quaternary, one-component plating such as In is performed after binary / ternary plating. And then diffusion (German Offenlegungsschrift 30 00 02).
No. 79).

According to Japanese Unexamined Patent Publication (Kokai) No. Heisei 3-215693, which analyzed the crystal structure of a Pb alloy-based overlay, random overlay is mainly composed of (111) and (200) and has other orientations. It is disclosed that the unidirectional orientation in the (200) direction improves seizure resistance.

According to JP-A-3-215694, which similarly analyzed the crystal structure of the overlay, the data of the Miller index integral intensity of the conventional overlay was converted from the intensity of (111) to 1, and the specific intensity of other orientations was converted. (RI) When calculated, RI ≒ 0.1-0.5. Also RI (200) ≒ 0.5
And the other orientations are RI (hkl) <0.2. Therefore, the overlay having this crystal orientation is (1)
11) The azimuth is the most preferred direction.
No sharp unidirectional orientation such as (00) orientation.

[0006]

Under general plating conditions using a conventional borofluoride bath, Pb or a Pb alloy requires (11
It has been found that the (1) or (100) orientation grows preferentially. However, the orientation does not have a remarkable unidirectional orientation, and the sum of the intensities of the other Miller indices is higher than the (111) or (100) orientation.

[0007] The overlay is required to have high fatigue strength during long-term use. In particular, in recent years, the load applied to the bearing has increased with the increase in the output of the engine, and a problem has occurred in that the bearing surface layer is peeled off by fatigue. Incidentally, the applicant filed an application for the above-mentioned German publication in 1979.
By around the time the output of the engine was not as high as it is now,
The fatigue of the overlay and the wear by the mating shaft often occur in parallel, and as described in the publication, it was effective to add a wear resistance improving element to the Pb alloy. In addition, bearing seizures caused by overlay corrosion are
The countermeasure against the addition of n was effective, and increasing the strength by setting the Sn amount to 5 to 20% was also effective in improving the fatigue resistance.

However, when a bearing having high wear resistance receives a high load from a mating shaft, wear due to fatigue of the overlay becomes significant. Therefore, it is considered that the overlay subjected to a high load via the oil film is not worn but is simply deformed. A part of the deformed Pb alloy makes metal contact, and the mating shaft scrapes the part, but this is a normal overlaying action and does not cause a bearing accident or the like. However, slips accumulate in the crystal in alloy portions that are not removed by the conforming action. It is assumed that the accumulation of the slip causes a micro crack first, and the crack propagates in the Pb alloy, eventually causing a large crack in the overlay, and appears as a phenomenon that the overlay peels off.

On the other hand, according to the above-mentioned Japanese Patent Application Laid-Open No. 3-215694, it is proposed to significantly improve the seizure resistance by significantly increasing the Miller index other than the (111) orientation. I do.
It is not sufficiently known in which crystal orientation the slip or crack propagation easily occurs in the Pb alloy. However, the present inventors have confirmed the following events from a fatigue resistance test of a practical sliding bearing. (1) Under general plating conditions using a conventional borofluoride bath, the orientation of a simple Miller index such as (100) or (111) grows preferentially. However, since the sum of the intensities of the other directions is higher, they are not unidirectionally oriented in the preferential growth direction. In such an overlay, the fatigue resistance hardly changes even if the strength in other directions is slightly increased or decreased. (2) If the orientation in a specific direction is made stronger than in (1) above, the fatigue resistance decreases as the strength increases.

The applicant of the present invention has been carrying out a study for improving the fatigue resistance by improving the composition of the overlay (German Patent Publication mentioned above), but newly controlling the orientation of the overlay to improve the fatigue resistance. Conducted research to increase the From the above findings, the present inventors have found that if the orientation is significantly more randomized than the overlay that tends to be oriented in a specific orientation made under the general plating conditions using a conventional borofluoride bath, the overlay has a fatigue resistance. The present invention has been completed by conducting research based on the idea that it is possible to enhance the present invention.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a plain bearing in which an overlay layer comprising a Pb or Pb alloy plating layer is formed on a lining with or without a barrier layer. X-ray of sample
The overlay with respect to the Miller index (111) plane due to diffraction
Specific intensity of the (111) plane of
The specific strength is the specific strength of the same Miller index plane of the powder standard sample.
(Degree) is set to 1 and (20) of the overlay layer
0) The specific strength of the plane is 1.1 to 4.5 times, and (22)
So that the specific strength of the (0) and (311) planes is 5 times or less.
The present invention relates to a plain bearing characterized in that the Pb or Pb alloy is randomly oriented .

Hereinafter, the reasons for limitation of the present invention will be described. In the present invention, when the peak intensity of the (111) plane is set to 1, and the ratio of the specific intensity of the other Miller index to the intensity of the powder standard sample exceeds 5, the orientation of one of the Miller index directions becomes stronger, and the orientation is higher than that of the conventional overlay. However, the fatigue resistance also deteriorates.

Although there are many plane orientations of the overlay, (111), (2)
00), (220), (311), (222), (40)
It is sufficient to measure the eight Miller indices 0), (331) and (420). That is, these indices are P
For alloy b, diffraction condition 2θ = λd (where λ = 1.5405)
(5 angstrom), the angle is in the range of θ = 0 to 90 °, and the measurement can be easily performed by operating the single device once.

The powder standard sample is a spherical powder having a size of 56 μm or less and the same composition as that of the overlay alloy. (111), (2)
00), (220), (311), (222), (40)
0), (331), (420) The peak intensity on each surface is 1
00,50,31,32,9,2,19,7. High peak intensity (111), (200), (22)
The crystal orientation can be compared by comparing the four surfaces (0) and (311) with the powder standard sample. The crystal orientation can be easily compared by adding (222), (400), (331) and (420) having low peak intensities and comparing.

In the present invention, the specific strength of the (200) plane
Is 1.1 to 4.5 times, (220), (311),
The specific strength of the (222), (400), (331) , and (420) planes is preferably 0.2 or more and 5 times or less , particularly 0.5 to 3.2 times, and more preferably 0.5 to 3.2 times. When the ratio is 0.7 to 1.9 times , the (111) plane and the other planes are present with almost the same intensity, and a remarkably random orientation can be obtained.

In the present invention, the thickness and composition of the lining and the composition and thickness of the overlay are all known. The overlay is Pb-Sn-In, Pb-S
Any of n-Cu system and Pb-Sn-In-Cu system may be used. Also, but not limited to, the alloy components of the overlay of the present invention comprise 5-20% by weight of Sn and 0.05-10% by weight of In, Cu, Tl, Mn, Bi, Ni, Ca, B.
What added at least 1 type of a to Pb can be used preferably.

Next, the method of Pb-Sn-Cu alloy plating will be described. That is, random plating characteristic of the present invention can be produced by performing electroplating according to the following plating bath composition and conditions, and adjusting the amount and current density and stirring speed of the organic additives at that time.

[0018] _{Pb (BF 4) 2 30~150g /} L Sn (BF 4) 2 10~ 30g / L Cu (BF 4) 2 0.5~ 5g / L H (BF 4) 2 40~150g / L gelatin 0-5 g / L Peptone 0-3 g / L Hydroquinone 1-5 g / L Current density 1-10 A / dm ² Bath temperature 20-35 ° C. Stirring speed 0-5 L / min The stirring speed is the circulation flow rate of a 100 L tank. Is represented.

The bath composition and conditions for the In plating are as follows. Sulfamic acid In 100-150 g / L Na sulfamate 100-200 g / L Sulfamic acid 10-40 g / L NaCl 30-60 g / L Glucose 5-11 g / L Triethanolamine 1.5-3.5 g / L Current density 1 ~ ^{2 A} / dm ² Bath temperature 28 ~ 32 ° C Stirring speed 0 ~ 5L / min

The heat treatment for diffusion of Im performed after the In plating is preferably performed at 155 ° C. × 40 minutes.

In order to disturb the conventional (111) preferential azimuthal growth, it is necessary to set a condition in which the current density is low within the above range.

[0022]

When the crystal direction of Pb is made random as described above, the slip direction becomes various Miller index directions, so that the propagation of fatigue cracks is hindered and the fatigue resistance is enhanced. No change was observed in the hardness due to the random orientation, nor in the surface and cross-sectional structure of the overlay observed with an optical microscope, so it is considered that the bearing performance other than fatigue resistance is equivalent to the conventional one. Actually, even in tests such as seizure resistance and abrasion resistance, no change due to randomization of the crystal direction was observed. Hereinafter, the present invention will be described more specifically with reference to examples.

[0023]

EXAMPLE First, Ni was added to kelmet (thickness = 0.2 mm).
Barrier plating was applied at 2 μm, and then an overlay having the composition shown in Table 1 was electroplated at 15 μm.

The composition of the Pb-Sn-Cu plating bath was constant for the following components, and the other components were varied as shown in Table 2.

Pb (BF ₄ ) ₂ 100 g / L Sn (BF ₄ ) ₂ 12 g / L Cu (BF ₄ ) _{2 2} g / L H (BF ₄ ) ₂ 40 g / L Bath temperature 27 ° C.

In is plated under a certain condition and then 150 ° C.
Diffusion was performed under the condition of × 40 minutes.

Thereafter, the peeling area (%) of the overlay of the sliding bearing test material was measured by a rotary load tester (shown as A in Table 1), and the peeling area (%) was similarly measured by a reciprocating dynamic load test. (Shown as B in Table 1). The test conditions are as follows.

Evaluation conditions (rotational load ) Tester Rotary load tester Surface pressure 27.3 MPa Rotation speed 8000 rpm Lubrication temperature 150 ° C Test time 5 hours Bearing width x diameter 17 mm x 42 mm

Evaluation conditions (reciprocating dynamic load ) Tester Reciprocating weight tester Surface pressure 63 MPa Revolution 3000 rpm Lubrication temperature 120 ° C. Test time 15 hours Bearing width × diameter 17 mm × 42 mm

[0030]

[Table 1] Nos. 1 to 5 are examples of the present invention, and Nos. 6 to 10 are comparative examples.

[0031]

[Table 2]

The X-ray diffraction conditions were as follows. Tube: Cu Tube voltage: 30 kV Tube current: 150 mA Monochromator: Used Goniometer: Wide-angle goniometer Sampling width: 0.020 ° Scanning speed: 2.00 ° / min Divergence slit: 1 ° Scattering slit: 1 ° Receiving slit : 0.15mm

FIG. 1 shows the results of X-ray diffraction of the test sample 1 of the present invention.
X-ray diffraction results of the comparative sample material 7 are shown in FIG.
In Table 1, test materials 1 and 8; 2 and 7; 3, 4, 5, 6
9 and 10 are examples in which the compositions are the same and the orientations are different. When these are compared, it is clear that when the crystal orientation is randomized, the area of fatigue delamination is drastically reduced. In particular, it is noted that the fatigue delamination areas of 1 and 4 in which the strengths of the eight indices are almost the same are small.

On the other hand, the test material 7 is an example in which the specific strength of (200) and (400) is remarkably increased, and has the largest fatigue peeling area. The test material 10 is a similar example. Sample 8 is an example in which the specific strength of only (200) exceeds 5, and has a large fatigue peeling area.

[0035]

As described above, the present invention is meaningful in the automobile industry because fatigue overlay, which is a problem in increasing the output of an engine, can be prevented by setting the overlay of the sliding bearings in a random orientation. Invention.

[Brief description of the drawings]

FIG. 1 is a chart showing an X-ray diffraction result of a test sample 1 of the present invention.

FIG. 2 is a chart showing an X-ray diffraction result of a comparative sample material 7;

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C25D 7/10 F16C 33/10

Claims (4)

(57) [Claims] 1. A mirror according to the sliding bearing forming an overlay layer made of Pb or Pb alloy plating layer without via or through the barrier layer on the lining, X-ray diffraction of a powder standard sample having the same composition as the overlay layer Index (11
1) Specific strength of the (111) plane of the overlay layer with respect to the plane
(Specific strength of other Miller index surfaces is the same as powder standard sample
When the specific intensity of the Miller index plane is set to 1
The specific strength of the (200) plane of the overlay layer is 1.1 to
A plain bearing wherein the Pb or Pb alloy is randomly oriented such that the ratio is 4.5 times and the specific strength of the (220) and (311) planes is 5 times or less. 2. The method according to claim 1, further comprising: (222), (400), (3 )
The sliding bearing according to claim 1, wherein the specific strength of each of the ( 31) and (420) faces is 5 times or less. 3. The method according to claim 2, wherein (220), (311), (22)
The plain bearing according to claim 2, wherein the specific strength of each of the (2), (400), (331) and (420) faces is 0.2 times or more. 4. The method according to claim 2, wherein (220), (311), (22)
The plain bearing according to claim 3, wherein the specific strength of each of the (2), (400), (331) and (420) faces is 0.5 to 3.2 times.