JP4750822B2 - Half bearing - Google Patents

Description

  The present invention relates to a half bearing in which a base material is provided with an overlay mainly composed of Bi.

  For internal combustion engines such as automobiles, plain bearings using Cu-based or Al-based bearing alloys are used. This plain bearing is formed in a cylindrical shape by combining two semicircular half bearings. A plain bearing (half bearing) is usually provided with an overlay on its surface in order to improve bearing characteristics. Patent Documents 1 and 2 are known as bearings having an overlay on the surface of the bearing alloy layer.

  In Patent Document 1, an overlay made of a Pb alloy is formed on the surface of a bearing alloy layer. The crystal structure of the Pb alloy includes a quadrangular pyramid crystal and a granular crystal. In the bearing of Patent Document 1, an aggregate of quadrangular pyramid crystals is formed at the center of the sliding surface of the overlay. In this structure, an aggregate of granular crystals is formed. According to this configuration, when viewed from the surface area level of the crystal, the surface area of the center portion of the overlay is enlarged, the oil retaining property is improved, and the non-seizure property is improved.

Patent Document 2 uses Bi or Bi alloy whose crystal size is smaller than that of Pb alloy for overlay, and the surface of the overlay is formed by dense crystallization of tetrahedral Bi or Bi alloy crystals. It is said that since it has fine irregularities, the oil retention is improved and the non-seizure property is improved.
JP-A-4-366020 Japanese Patent Laid-Open No. 2003-156045

  However, in this Patent Document 1, since the overlay is made of a Pb alloy, even with the above-described configuration, the crystal size is large, so that the fatigue resistance is poor. Further, since Pb is an environmental pollutant, there is a demand for avoiding the use of Pb.

  Further, due to the demand for weight reduction of the internal combustion engine, for example, a housing to which a slide bearing such as a connecting rod is assembled is made thinner. As the housing becomes thinner, the rigidity of the housing decreases and the housing itself is easily deformed. For this reason, the housing itself is deformed by the dynamic load of the shaft supported by the slide bearing, and accordingly, the slide bearing itself is easily bent and deformed, and fatigue is likely to occur. A bearing used in an environment where such repeated bending acts must have high bending fatigue strength. However, in Patent Document 2, Bi or Bi alloy is used for the overlay instead of the Pb alloy overlay, but the crystal size is almost uniform over the entire circumferential region. Environmentalization has the problem of fatigue early.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a half bearing capable of improving the bending fatigue strength while maintaining good non-seizure properties.

  For example, in a slide bearing attached to an engine block, two halved bearings are fixed by a bearing cap bolted to the engine block, and in a slide bearing attached to the connecting rod, a rod cap bolted to the connecting rod The two half bearings are fixed by. In such a mounting structure, the butted portions of the two half bearings are positioned at the bolted portion of the cap. In such a mounting structure, both end portions of the cap that are bolted are likely to be deformed. For this reason, repeated bending acts on both end portions in the circumferential direction of the half bearing, and bending fatigue is likely to occur. There are circumstances.

  Based on such circumstances, the present inventor has conducted extensive experiments to realize a half bearing with improved bending fatigue strength at both end portions in the circumferential direction without impairing non-seizure properties. If Bi, which is not an environmental pollutant, is used as the element constituting the material, and the size of the Bi overlay crystal is different between the portion where the main load acts and the portion where the repeated bending acts, the non-seizure property The present invention has been made by obtaining the idea of a half bearing having an excellent bending fatigue strength without impairing the above.

The present invention relates to a half bearing in which an overlay is applied to a base material, wherein the overlay is formed from Bi or Bi alloy, and the area of the overlay is divided into an end side area on both sides in the circumferential direction, and the both end side areas. divided into a sandwiched intermediate region, the size of the Bi crystal, Ru der those characterized by having a reduced toward the end portion side region than the intermediate region.

  It is preferable that the Bi alloy contains Cu, Sn, or In as an additive element and is added in a total amount of 10% or less. When the total amount is 10% or less, the additive element is dissolved in the Bi base, and the strength of the overlay base can be increased.

  The basic form of the half bearing of the present invention is shown in FIGS. The half bearing 1 of FIGS. 1 and 2 is provided with a bearing alloy layer 3 made of a Cu alloy or an Al alloy on a back metal layer 2 made of steel, and an intermediate layer 4 is provided on the bearing alloy layer 3. Further, an overlay 5 made of Bi is provided on the intermediate layer 4. Here, the base material referred to in the present invention refers to a member to which an overlay is applied, and in the examples of FIGS. 1 and 2, refers to a back metal layer 2, a bearing alloy layer 3, and an intermediate layer 4. However, in some cases, the intermediate layer may be omitted, or the overlay may be directly applied to a halved base material made of, for example, iron. Also, as shown in FIGS. 2 (a) and 2 (b), the area of the overlay 5 is sandwiched between the end side areas (shown by A in FIGS. 1 and 2) on both sides in the circumferential direction and the both end side areas. In general, the intermediate region includes a main load portion, that is, a portion that mainly receives the load of the shaft when divided into divided intermediate regions (indicated by B in FIGS. 1 and 2).

By making the size of the Bi crystal in the end region smaller than that of the Bi crystal in the intermediate region, the strength of the end region can be increased without impairing the seizure property, and the bending fatigue strength is improved. be able to.
In this end side region, since the Bi crystal is small, the valley formed between the crystals is relatively shallow. However, in the end side region, the larger load does not act in the intermediate region where the main load acts, so the wear progresses. However, the oil retaining function can be maintained for a long time.

  For example, the following method is effective to make the size of Bi crystals different between the intermediate region and the end side region. That is, the Bi overlay is deposited by electroplating.

  Bi plating is performed by stirring the plating solution with a jet. As shown in FIG. 6, the conventional jet agitation uses a jet agitator 102 having a nozzle 101 for discharging a plating solution. As shown in FIG. 6A, the nozzle 101 is arranged slightly apart from the center of the arc of the half bearing 103 (bearing alloy layer). As shown in FIG. 6B, the nozzle 101 has a plurality of discharge ports 104 formed in a line along the axial direction of the half bearing 103. Therefore, when the plating solution is discharged from the nozzle 101, the plating solution reaches the entire inner surface of the half bearing 103, and Bi crystals having a uniform size are deposited.

  Here, the present inventor makes use of the technology that the Bi crystal constituting the overlay becomes fine when the jet stirring (discharge) of the plating solution is strong, and the Bi crystal becomes large when the jet stirring is weak. An inventive overlay was formed.

  This inventor performed Bi plating using the jet-flow stirring apparatus 6 as shown in FIG. The jet stirring device 6 has a configuration in which two rows of discharge ports 8 of the nozzle 7 are provided in parallel to the axial direction of the nozzle 7, and each discharge port 8 has end portions on both sides in the circumferential direction of the adjacent bearing alloy layer 3. Is directed to the side area. At this time, when the angle of the discharge port 8 adjacent in the circumferential direction is expressed as θ, the angle θ is in the range of 90 to 140 degrees. In addition, the nozzle 7 is disposed substantially at the center of the half bearing 1 that performs the overlay 5. As a result, the plating solution discharged from the discharge port 8 is more strongly jet-stirred on the end side region side on both sides in the circumferential direction of the bearing alloy layer 3 (intermediate layer 4) than in the intermediate region side. As shown, the size of the Bi crystal in the end region can be made smaller than the size of the Bi crystal in the intermediate region.

The magnitude of the Bi crystal, be less than 0.4 .mu.m ² at the end side region, it has preferably be 0.4 to 1.5 .mu.m ² at an intermediate region. In the present invention, the size of Bi crystals is defined as follows. That is, the overlay is photographed from the upper surface with an electron microscope. 25 μm ² (5 μm × 5 μm) is cut out from the photographed image, the number of particles present therein is counted, and a value obtained by dividing the area of 25 μm ^{2 by} the number of particles is defined as the size of Bi crystals.

By making the size of the Bi crystal in the end side region less than 0.4 μm ² , the strength of the overlay can be increased. As a result, the strength as a half bearing can be increased, and bending fatigue can be increased. Strength can be improved. By the way, as shown in FIG. 1, by making the size of the Bi crystal in the intermediate region larger than that of the Bi crystal in the end region, there is a deep valley between adjacent Bi crystals in the intermediate region. It is formed. As a result, the lubricating oil is likely to accumulate in the valleys between the crystals in the intermediate region, so that good oil retention and consequently non-seizure properties are not impaired. Further, even if the wear of the overlay progresses and the intermediate region wears, the crystals in the intermediate region are large, so that they remain for a long period of time, and the oil retaining property and non-seizure property can be maintained for a long time.

If the size of the Bi crystal in the intermediate region is 0.4 μm ² or more, the valley between the Bi crystals becomes deeper, and a large amount of lubricating oil can be stored, impairing good oil retention and non-seizure properties. There is no. On the other hand, when the thickness is 1.5 μm ² or less, it is possible to prevent the strength of the overlay from being lowered.

In addition, by setting the size of the Bi crystal in the end side region to less than 0.3 μm ² , the end portion can have higher strength, and as a result, the strength as a half bearing can be further increased. And the bending fatigue strength can be further improved.
When the size of the Bi crystal in the intermediate region is 0.7 μm ² or more, good oil retention and non-seizure properties are realized for a longer period. On the other hand, when the thickness is 1.3 μm ² or less, it is possible to more reliably prevent the strength of the overlay from being lowered.

  The total surface area of the both end side regions is preferably 10 to 50% of the entire surface area of the overlay (claim 3). The surface area is the area of a plane in a state where the half bearing is developed.

  In order to prevent fatigue due to bending deformation of the half bearing, it is preferable that the total surface area of both end side regions is 10% or more of the surface area of the entire overlay. In order to obtain a sufficient area of the intermediate region to receive the main load, it is preferable that the total surface area of the both end side regions is 50% or less of the entire surface area of the overlay. Furthermore, the area is preferably 20 to 40%.

Examples of the present invention will be described below.
In order to confirm the effect of the present invention, the half bearing samples (Examples 1 to 8 and Comparative Examples 1 to 5) shown in the following Tables 1 and 2 are manufactured, and end fatigue tests and seizure tests are performed. It was.

  The production method of the sample was simply described. First, a bearing alloy layer was lined on a steel plate constituting a back metal layer to produce a bimetal, and the bimetal was processed into a semicircular shape to obtain a half bearing. Thereafter, Ag plating as an intermediate layer was applied to the bearing alloy layer of the half bearing, or Bi or Pb alloy was plated without Ag plating, and an overlay was deposited to obtain the above samples.

  In Examples 1 to 10, in Examples 5 to 8 and 10 without an intermediate layer, a bimetal composed of a back metal layer and a bearing alloy layer is manufactured, and the surface of the bearing alloy layer of the bimetal is subjected to ultrasonic cleaning and electrolysis. After degreasing and pickling, the bearing alloy layer was manufactured by performing Bi plating (thickness 10 μm). In Examples 3 and 8 having an intermediate layer, a bimetal made of a back metal layer and a bearing alloy layer is manufactured, and the surface of the bimetallic bearing alloy layer is electrolytically degreased, pickled, and an intermediate layer made of Ag. (Thickness 5 μm) was provided, and Bi plating (thickness 10 μm) was performed on the intermediate layer.

In addition, the plating solution used for Bi plating used the general thing, for example, 10-70 g / l of bismuth oxide, 30-150 ml / l of methanesulfonic acid, and 20-60 ml / l of additives. The plating conditions are a current density of 1 to 6 A / dm ² and a discharge rate of 5 to 50 l / min. The jet stirring used for Bi plating used the jet stirring apparatus 6 shown in FIG. The diameter of the discharge port 8 of the nozzle 7 of the jet stirring device 6 is 2 to 4 mm, the pitch in the axial direction of the discharge port 8 is 30 mm, and the angle θ is 90 to 140 degrees. When the angle θ is 90 degrees, the total surface area of the both end side regions of the regions constituting the overlay is about 50% of the surface area of the overlay, and when the angle θ is 140 degrees, the surface area of the both end side regions. The total of about 10% of the surface area of the overlay.

The end fatigue tests and seizure tests performed on Examples 1 to 10 and Comparative Examples 1 to 4 are as follows.
(1) End fatigue test This test was performed on Examples 1 to 4 and Comparative Examples 1 and 2. In the test, for Examples 1 to 4 and Comparative Examples 1 and 2, the two half bearings are shifted by ΔL in the radial direction by ΔL in the radial direction as shown in FIG. In this state, an end fatigue test was conducted under the test conditions shown in Table 3.

  Thus, by shifting the abutting end, the shaft load is easily applied to the end portion (end portion side region) of the half bearing, and the bending fatigue strength of the end portion of the half bearing can be confirmed. The load was applied by 1 MPa every minute, and the time from when the load reached 30 MPa until fatigue occurred was measured. Moreover, the test was implemented 3 times each about Examples 1-4 and Comparative Examples 1 and 2. The hatching at the right end of the bar graph in FIG. 5 indicates the variation range of three tests.

(2) Baking test This test was performed on the conditions shown in Table 4 for Examples 5 to 10 and Comparative Examples 3 and 4. The results are shown in Table 2.

Next, the results of the above test are analyzed.
Considering the results of the end fatigue test, it is understood that Examples 1 to 4 have higher fatigue resistance than Comparative Example 1 in which the size of Bi crystals is uniform throughout. Further, it is understood from the comparison between Example 4 and Comparative Example 2 that if the overlay is made of Bi, the fatigue resistance can be improved.
Considering the results of the seizure test, it is understood that Examples 5 to 10 show non-seizure properties substantially equivalent to those of Comparative Examples 3 and 4. From this result, it is understood that good non-seizure property is maintained even if the crystal region in the end portion region is reduced.
The same tendency was observed even when a Bi alloy (Bi-1Cu (mass%) or less, Bi-1Sn, etc.) was used as the overlay, and an Ag alloy, Cu, Cu alloy (Cu-5Zn, etc.) was used as the intermediate layer. .

Schematic showing the size of crystals in the overlay of the present invention (A) is a sectional view of a half bearing, (b) is a developed view of the inner circumference side of the half bearing. It is a figure which shows the jet stirring apparatus for forming the overlay of the half bearing of this invention, (a) is sectional drawing, (b) is a top view The figure which shows the attachment state of the half bearing to the end fatigue testing machine Diagram showing end fatigue test results It is a figure which shows the jet flow stirring apparatus for forming the overlay of the conventional half bearing, (a) is sectional drawing, (b) is a top view

Explanation of symbols

  In the drawings, 1 is a half bearing, 2 is a back metal layer, 3 is a bearing alloy layer, 4 is an intermediate layer, and 5 is an overlay.

Claims (7)

In half bearings with an overlay on the base material,
The overlay is formed from Bi or Bi alloy;
The area of the overlay is divided into an end side area on both sides in the circumferential direction and an intermediate area sandwiched between the both end side areas,
The size of the Bi crystal is smaller in the end region than in the intermediate region;
And wherein the crystal size of Bi of said end-side region 0 .mu.m ² exceeded is less than 0.4 .mu.m ^2, in which the crystal size of Bi of the intermediate region and 0.4 .mu.m ² or 2.1 .mu.m ² or less Half bearing. The half bearing according to claim 1, wherein the size of the Bi crystal in the intermediate region is 1.5 μm ² or less.   3. The half bearing according to claim 1, wherein a total surface area of the both end side regions is 10 to 50% of a surface area of the entire overlay. The substrate comprises a backing metal layer, a bearing alloy layer, and an intermediate layer,
The half bearing according to any one of claims 1 to 3, wherein the intermediate layer is made of Ag, an Ag alloy, Cu, or a Cu alloy. An arc base material;
Discharged in a range of heart 90 to 140 ° in the arc of the base material, stronger jet than the intermediate region side toward the end portion side region side on both sides of the circumferential direction of the substrate is sandwiched the end portion side region An overlay having Bi crystals formed by an agitated Bi plating solution;
A half bearing characterized by comprising. The size of the Bi crystal of the overlay is made smaller in the end side region than in the intermediate region,
And wherein the crystal size of Bi of said end-side region 0 .mu.m ² exceeded is less than 0.4 .mu.m ^2, in which the crystal size of Bi of the intermediate region and 0.4 .mu.m ² or 2.1 .mu.m ² or less The half bearing according to claim 5.   The end portion on the end side region side is located at both end portions of the component constituting the housing, which are assembled to a housing having bolted components. The half bearing according to any one of 6 above.

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