GB2252565A

GB2252565A - Bearings

Info

Publication number: GB2252565A
Application number: GB9202766A
Authority: GB
Inventors: Masahiro Nakano; Tadashi Tanaka; Masaaki Sakamoto; Yoshiaki Satoh
Original assignee: Daido Metal Co Ltd
Current assignee: Daido Metal Co Ltd
Priority date: 1991-02-08
Filing date: 1992-02-10
Publication date: 1992-08-12
Anticipated expiration: 2012-02-10
Also published as: DE4201761A1; KR950005844B1; GB9202766D0; KR920016733A; JPH04259345A; JP2705781B2; GB2252565B

Abstract

A bearing material for a large internal combustion engine is disclosed which comprises a backing metal of steel 1, a bonding layer 2 of aluminium or an aluminium alloy formed on the backing metal, a bearing alloy layer 3 formed on the bonding layer, and optionally a surface layer 4 formed on the bearing alloy layer and comprising lead, tin or an alloy thereof. The bearing alloy layer comprises, by weight, from 40 to 50% tin, from 0.5 to 10% lead, from 0.1 to 1.5% copper, the balance being aluminium and any incidental impurities. The bearing alloy layer may further comprise, by weight, no more than 5% in total of at least one of the elements manganese, nickel, silicon, silver, magnesium, antimony and/or zinc. These bearing materials may have superior seizure resistance and fatigue resistance properties. <IMAGE>

Description

BEARINGS This invention relates to bearing materials, such as bearings, suitable for large engines.

Japanese Patent Publication Nos. 61-17893 and 61-6138 relate to bearing metals that may have good seizure resistance and good embedability but are not always satisfactory in fatigue strength, particularly in view of recent and rapid advances in internal combustion engine technology. Therefore, there is now a need for bearings metals having improved fatigue strength.

With this problem in mind it is an object of the present invention to provide a bearing material, such as a bearing, for large engines which may have excellent fatigue strength without seizure resistance being effected.

Thus according to a first aspect of the present invention there is provided a bearing material, such as a bearing, comprising a backing metal and a bonding layer of aluminium or an aluminium alloy underneath a bearing alloy layer comprising from 40 to 50% tin (Sn), from 0.5 to O% lead (Pb), from 0.1 to 1.5% copper (Cu), the balance being aluminium and any incidental impurities, and optionally a surface layer.

Thus preferably the bonding layer will be bonded to the backing metal. Alternatively or in addition the bearing alloy layer may be bonded to the bonding layer.

Furthermore, the surface layer, if present, can either be bonded directly to the bearing alloy layer or separated by one or more intermediate layers, such as a nickel layer. Thus although in preferred embodiments the bearing material of the present invention has either a three or four-layered structure (namely including a backing metal, bonding layer, bearing alloy layer and, if present, a surface layer) the invention nevertheless contemplates one or more layers being interposed between any of these layers thus mentioned.

Thus the present invention in a preferred embodiment relates to a bearing material suitable for a large engine, comprising a backing metal such as steel, a bonding layer of aluminium or aluminium alloy formed on the backing metal, and a bearing alloy layer formed on the bonding layer, the bearing alloy layer comprising, by weight, from 40 to 50% tin, from 0.5 to 10% lead, from 0.1 to 1.5% copper, the balance being aluminium and any incidental impurities.

The invention also encompasses a bearing material suitable for large engines, comprising a backing metal such as steel, a bonding layer of aluminium or an aluminium alloy formed on the backing metal, a bearing alloy layer formed on the bonding layer, and a surface layer formed on the bearing alloy layer, the surface layer being lead, tin or an alloy thereof and the bearing alloy layer comprising, by weight, from 40 to 50% tin, from 0.5 to 10% lead, from 0.1 to 1.5% copper, the balance being aluminium and any incidental impurities.

The bearing alloy layer can preferably further comprise, by weight, no more than 5% in total of at least one of the elements manganese (Mn), nickel (Ni), silicon (Si), silver (Ag), magnesium (Mg), antimony (Sb) and/or zinc (Zn).

In the previously mentioned Japanese prior art publications, more than 50% tin is required in order to ensure acceptable seizure resistance. However, in these publications where the tin content exceeds 50%, the desired fatigue strength cannot be obtained.

In the bearing materials of the present invention the amount of tin can be reduced in order to improve the fatigue strength, but lead is added in order to achieve seizure resistance of similar levels to those achieved in the prior art.

The reasons for the preferred compositions of each layer of the bearing material suitable for large engines according to the present invention, as well as any effects of each layer and component , will now be explained in further detail.

1. The backing metal, such as steel (suitably in the form of a layer).

Conventional, known steels, such as carbon steel of ordinary structure as defined in JIS (Japanese Industrial Standards), can be used as the backing metal in the bearing materials of the present invention. The backing metal is suitably from 1 to 20 mm thick, such as from 1 to 2 mm thick.

2. The intermediate (or bonding) layer.

The intermediate layer (or bonding layer) may enhance the bonding between the backing metal (e.g. steel) and the bearing alloy layer. This layer can be aluminium, such as conventionally used pure aluminium or an aluminium alloy, such as comprising, by weight, from 0.1 to 2% in total of at least one of the elements copper, silicon, manganese and/or zinc. An aluminium alloy is used when a greater strength is required.

If the amounts of these additives included in the aluminium alloy is below 0.1%, then the effects intended to be conferred by the added components may not be obtained, and so this preferred lower limit is set. On the other hand, if this amount exceeds 2%, this can invite brittleness, and may not be suitable for practical purposes.

The bonding layer is suitably from 0.01 to 0.15 mm thick, such as from 0.02 to 0.03 mm thick.

3. The bearing alloy layer.

(a) Tin: 40 to 50%.

If the tin content is less than 40%, the seizure resistance and embedability may both be unsatisfactory.

On the other hand if this amount exceeds 50%, the fatigue strength may become insufficient.

(b) Lead: 0.5 to 10%.

Lead may co-operate with tin to form an alloy that can enhance the lubricating properties of tin and increase the compatibility thereof. If the lead content is less than 0.5%, then the effects intended by the addition of lead may not be obtained. On the other hand, if this amount exceeds 10%, the melting point may become too low, which may pose production problems.

(c) Copper: 0.1 to 0.5%.

Copper can enhance the fatigue strength (which is one of the bearing materials' properties) and may also improve the strength of bonding of the bearing alloy layer to the surface layer, when present. If the copper content is less than 1%, the effects intended by the addition of copper may not be obtained. On the other hand, if this amount exceeds 1.5% the hardness of the alloy may become too . high, so that the initial compatibility and embedability may be adversely affected. If the ductility is adversely affected, then production may become more difficult.

The bearing alloy layer is preferably from 0.2 to 3.0 mm thick, such as from 0.40 to 0.45 mm thick.

(d) At least one element which is Ni, Si, Ag, Mg, Mn, Sb and/or Zn: not more than 5% in total.

One or more of these elements, which are optional, can be added in order to improve the mechanical strength of the aluminium matrix. In this amount exceeds 5%, the initial compatibility and embedability may be adversely affected, and therefore the upper limit is preferably 5%.

4. The surface layer.

This layer, if provided, may enhance the seizure resistance, embedability and initial compatibility. The layer suitably comprises lead, tin or an alloy thereof.

In order to further enhance performance, copper and/or indium (In) may also be added. Preferably the layer is tin or an Sn-Pb or Sn-Pb-Cu alloy. In the latter cases lead is preferably the major component, for example being present at from 80 to 95%, with perhaps from 1 to 5% copper (if present) the balance being tin and any unavoidable impurities.

The surface layer is suitably from 1 to 30 Am thick, such as from 15 to 15 Sm.

Furthermore, in order to improve the bonding between the bearing alloy layer and the surface layer, an (e.g. thin) layer such as a layer of nickel may be formed between the bearing alloy layer and the surface layer, preferably by electroplating.

The surface layer may be formed on the bearing alloy layer by a PVD process or an electroplating method.

Suitably the overall thickness of the bearing material is from 1 to 2 mm.

The present invention will now be described by way of example with reference to the accompanying Examples and drawings which are provided by way of illustration but not limitation. In the drawings: Fig. 1 is a section of a three-layered bearing material according to the present invention; and Fig. 2 is a section of a four-layered bearing material also according to the present invention.

EXAMPLES 1 TO 12 AND COMPARATIVE EXAMPLES 13 TO 18 Table 1 gives the chemical compositions of twelve examples of different bearing alloy layers (and accompanying surface layers, if present) used in twelve bearing materials according to the present invention.

Table 2 similarly shows the chemical compositions of six examples of bearing alloy layers used in conventional, prior art, bearing materials.

Alloy sheets having the compositions shown in Tables 1 and 2 were superimposed on an aluminium foil, and were together passed through a rolling mill to form a composite laminate sheet having a thickness of 1 mm.

This composite sheet was superimposed on a backing metal steel plate having a thickness of 2 mm, and were rolled together to provide a three-layer composite laminate sheet composed of the bearing alloy layer, the intermediate bonding layer of aluminium and the backing steel layer. The thickness of this three-layer composite was 1.65 mm. The thickness of the bearing alloy layer of the three-layer composite was 0.42 to 0.43 mm, the thickness of the intermediate aluminium layer was 0.02 to 0.03 mm, while the thickness of the backing steel layer was 1.2 mm.

The three-layer composite was then press-worked into a bearing of semi-circular shape having a diameter of 53 mm and length of 17 mm.

For those bearings having a surface layer the bearings were coated with a surface layer by electroplating using a boron fluoride bath, to thereby form a four-layer bearing material, the surface layer having a thickness of 20 Mm. The three-layer and four-layer bearing materials thus formed were then subjected to seizure and fatigue tests.

Figs. 1 and 2 are sections of the three-layer and four layer bearing materials respectively. In these figures reference numeral 1 denotes the backing metal (e.g. a steel layer), reference numeral 2 the bonding layer (e.g.

aluminium), reference numeral 3 the bearing alloy layer and reference numeral 4 the surface layer.

Table 3 shows the conditions used in the fatigue test, and Table 4 shows the conditions of the seizure test.

Table 5 gives the results of the fatigue test while Table 6 gives the results of the seizure test.

TABLE 1 Bearing materials of the present invention

Ex. Chemical composition of bearing Chemical composition of Kind No. alloy layer (wt. %) surface layer (wt. %) Sn Pb Cu Mn Ni Si Ag Mg Sb Zn Al Pb Sn Cu In 1 40 7.0 0.1 - - - - - - - balance balance 10 - 2 40 8.0 0.4 0.3 0.5 - - - - - balance - - - 3 40 10.0 0.4 - - 1.0 - - 0.3 - balance - - - Products 4 45 3.0 0.5 - - - - 0.3 - - balance - 100 - of present 5 45 5.0 0.6 - - - 1.0 - - 1.0 balance - - - invention 5 45 5.0 0.5 - - 0.7 - - 0.3 - balance - - - 6 45 5.0 0.8 - - - - - - - balance - - - 7 45 5.0 0.5 0.3 - - - - - 1.0 balance balance 10 3 8 50 0.5 0.6 - 0.5 - - 0.3 - - balance - - - 9 50 3.0 0.8 - - - - - - - balance - - - 10 50 5.0 0.8 - - 1.0 - - 0.5 - balance - - - 11 50 10.0 0.8 - - 1.5 3.0 - - - balanc - - - 12 50 9.0 1.5 - - - - - - - balance - - - TABLE 2 Prior art bearing materials

Kind Ex. Chemical composition of Chemical composition of No. alloy layer (wt. %) surface layer (wt. %) Sn Pb Cu Mn Ni Si Ag Mg Sb Zn Al Pb Sn Cu In 13 55 - 0.3 - - - - - - - balance - - - Prior art 14 55 - 0.3 - - - - - - - balance balance 10 3 Products 15 55 - 0.4 - - 1.5 - - - - balance - - - 16 55 - 0.4 - - 1.5 - - - - balance - 100 - 17 55 - 1.0 - - - - - - - balance - - - 18 55 - 1.0 - - - - - - - balance balance 10 - Table 3 Conditions of the fatigue test

Dynamic load testing machine Item Dimensions Unit 53 dia. x 17 length Bearing metal size x 1.5 thickeness mm Revolution 3000 rpm Velocity 8.3 m/s Lubricating oil SAE20 Inlet temperature 60 C Oil supply pressure 3.0 kgf/cm2 Lubricating method Oil feed to shaft Testing time 20 Hrs Shaft material S55C Shaft roughness 1.0 Rmax ijm Shaft hardness 55 < BRC Evaluation method It is decided that a fatigue occurs when the ratio of the area of the fatigue portion to the projected area of the bearing is not less than 5%.

Table 4 Conditions of the seizure test

Static load testing machine Item Dimensions Unit Inner diameter of bearings x 1.5 thickness mm ~ Revolution 3000 rpm Velocity 10.0 m/s Lubricating oil SAE209 Inlet temperature 98-102 OC Oil feed amount 12.5 cc/min Shaft material S55C Shaft roughness 1.0 > Rmax pm Test method A step-up method in which the load is increased 50 kgf/cm2 every 10 minutes.

Evaluation method Seizure is judged when bearing back temperature rises over 2200C or electric current exceeds 20A. Table 5 FATIGUE TEST RESULTS

Kind of Sample Bearing load (kgf/cm2) product No. 100 150 200 250 1 I 1 1 I x I 1 of present 4 inven tion 5 1 6 1 7 1 8 9 10 11 I 12 1 13 14 Prosucts 16 17 18 * The portion marked in dark represents the range in which test results fluctuated. Table 6 SEIZURE TEST RESULTS

fKind of Sample Bearing load (kgf/cm2) product No. 850 900 950 1000 1050 1 2 1 Product 3 of tion 5 1 6 1 7 1 8 9 1 0 ~~~ ~~ = 11 12 -3 1 14 Prior ---- --------- ---- ------- art 15 1 Products 16 ---- ---- ---- ---- ---- = 16 17 1 18 * The portion marked in dark represents the range in which test results fluctuated.

The accompanying Examples demonstrate that the bearing materials of the present invention can have the following advantages.

As will be appreciated from the fatigue test results in Table 5, each of the bearings of the present invention had improved fatigue strength when compared with the prior art bearings. This can be achieved, it is believed, by limiting the tin content to no more than 50%.

As can be seen from the seizure test results of Table 6, each of the bearings of the present invention had a better seizure resistance than any of the prior art bearings. It is thought that this is caused by lead alloying with tin, thereby improving the lubricating properties of tin.

From the test results, each of the bearings of the present invention had greater fatigue strength without affecting the seizure resistance when compared with the prior art bearings.

The bearing materials of the present invention can be suitably used as the bearings for large engines which often require increased fatigue strength.

Claims

1. A bearing material comprising a backing metal and a bonding layer of aluminium or an aluminium alloy underneath a bearing alloy comprising from 40 to 50% tin, from 0.5 to 10% lead, from 0.1 to 1.5% copper, the balance being aluminium and any incidental impurities, and optionally a surface layer.

2. A bearing material according to claim 1 wherein the bearing alloy layer further comprises, by weight, no more than 5% in total of at least one of the elements manganese, nickel, silicon, silver, magnesium, antimony and/or zinc.

3. A bearing material as claimed in claim 1 or 2 wherein the bonding layer is bonded to the backing metal.

4. A bearing material as claimed in any preceding claims wherein the bearing alloy layer is bonded to the bonding layer.

5. A bearing material as claimed in any preceding claim wherein the surface layer is bonded to the bearing alloy layer.

6. A bearing material as claimed in any of claims 1 to 5 wherein the surface layer is separated from the bearing alloy layer by a nickel layer.

7. A bearing material as claimed in claim 6 wherein the nickel layer is formed by electroplating.

8. A bearing material as claimed in any preceding claim wherein the surface layer, if present, has a thickness of from 1 to 30 pm.

9. A bearing material as claimed in any preceding claim wherein the surface layer, if present, has a thickness of from 15 to 25 pm.

10. A bearing material as claimed in any preceding claim wherein the bearing alloy layer has a thickness of from 0.2 to 3.0 mm.

11. A bearing material as claimed in any preceding claim wherein the bearing alloy layer has a thickness of from 0.42 to 0.43 mm.

12. A bearing material as claimed in any preceding claim wherein the bonding layer has a thickness of from 0.01 to 0.15 mm.

13. A bearing material as claimed in any preceding claim wherein the bonding layer has a thickness of from 0.02 to 0.03 mm.

14. A bearing material as claimed in any preceding claim wherein the backing metal is steel.

15. A bearing material as claimed in any preceding claim wherein the backing metal has a thickness of from 1 to 20 mm.

16. A bearing material as claimed in any preceding claim which has an overall thickness of from 1 to 2 mm.

17. A bearing material as claimed in any preceding claim wherein the surface layer is lead, tin, or an alloy thereof.

18. A bearing material as claimed in claim 17 wherein the alloy additionally comprises copper and/or indium.

19. A bearing material as claimed in claim 17 wherein the surface layer is tin.

20. A bearing material as claimed in claim 17 or 18 wherein the surface layer is a Sn-Pb or an Sn-Pb-Cu alloy.

21. A bearing material as claimed in any of claims 2 to 20 wherein the bearing alloy layer additionally comprises silicon or antimony.

22. A bearing material as claimed in any preceding claim wherein the bonding layer is aluminium.

23. A method of manufacturing a bearing material, the method comprising providing a backing metal and forming a bonding layer of aluminium or an aluminium alloy underneath a bearing alloy layer comprising from 40 to 50% tin, from 0.5 to 10% lead, from 0.1 to 1.5% copper, the balance being aluminium and any incidental impurities, and optionally forming, where necessary, a surface layer.

24. A method as claimed in claim 23 additionally comprising: (a) bonding together the bonding layer and bearing alloy layer to form a laminate; (b) bonding the so formed laminate to the backing layer; (c) optionally and where necessary shaping the resultant product; (d) optionally and where necessary forming a nickel layer on the bearing alloy layer; and (e) optionally and where necessary forming a surface layer.

25. A method as claimed in claim 24 wherein the nickel layer and/or surface layer are formed by electroplating.

26. A method as claimed in claim 25 wherein the surface layer is formed by electroplating in a boron fluoride bath.

27. A method as claimed in any of claims 23 to 26 for manufacturing a bearing material as claimed in any of claims 1 to 22.

28. A bearing material substantially as herein described with reference to any of Examples 1 to 12.

29. A method of manufacturing a bearing material substantially as herein described with reference to any of Examples 1 to 12.