GB2252564A

GB2252564A - Bearings

Info

Publication number: GB2252564A
Application number: GB9202744A
Authority: GB
Inventors: Tadashi Tanaka; Masaaki Sakamoto; Yoshiaki Satoh; Masahiro Nakano
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: GB2252564B; JP2705782B2; JPH04350141A; DE4201793C2; DE4201793A1; KR950005845B1; KR920016734A; GB9202744D0

Abstract

A bearing material suitable for large internal combustion engines is disclosed which has either a three-layered structure consisting of a steel backing metal 1, an aluminium or aluminium alloy adhesive layer 2 and a bearing alloy layer 3, or a four-layered structure having a surface layer 4 in addition to the three layers which is lead, tin or an alloy thereof. The bearing alloy layer comprises from 35 to 65% by weight tin, 0.5 to 10% by weight bismuth, 0.1 to 1.5% by weight copper, and optionally 5% by weight or less of one or more of the elements manganese, nickel, silicon, silver, magnesium, antimony and/or zinc, the balance being aluminium and any incidental impurities. Such bearing materials may possess superior anti-seizure properties and display a high fatigue resistance. <IMAGE>

Description

BEARINGS The present invention relates to bearing materials, e.g.

bearings, that are suitable for large engines.

Japanese Patent Examined Publication Nos. 61-6138 and 6117893 relate to bearings for large engines which may have good anti-seizure properties and good foreign matter embedding properties. However these bearings for large internal combustion engines often do not meet the fatigue resistance levels now required as a result of recent and rapid developments in internal combustion engine technology. Therefore, bearings for large internal combustion engines having superior fatigue resistance are now sought.

An object of the present invention is to provide bearing materials, such as bearings, for large engines, that may have superior anti-seizure properties and high fatigue resistance.

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 an aluminium (Al) or Al alloy adhesive layer underneath a bearing alloy layer which comprises from 35 to 65% by weight of tin (Sn), 0.5 to 10% by weight of bismuth (Bi), from 0.1 to 1.5% by weight copper (Cu) the balance being Al and any incidental impurities.

The bearing material may optionally be provided with a surface layer that is lead (Pb), tin or an alloy thereof.

Preferably the bearing alloy will further comprise 5% by weight or less of one of the elements manganese (Mn), nickel (Ni), silicon (Si), silver (Ag), magnesium (Mg), antimony (Sb) and/or zinc (Zn).

Suitably the adhesive layer will be bonded to the backing metal, which will preferably be steel. The bearing alloy layer will thus preferably be in contact with the adhesive layer (e.g. to form a three layered structure).

Suitably the surface layer will be in contact with, such as formed on, the bearing alloy layer (for example in a four layered structure).

Thus the invention encompasses the following four preferred bearing materials A to D.

A. A bearing material for a large engine comprising a three-layered structure having a backing metal such as steel, an Al or Al alloy (adhesive or bonding) layer and a bearing alloy layer comprising from 35 to 65% by weight of tin, 0.5 to 10% by weight% of bismuth, 0.1 to 1.5% by weight of copper, the balance being Al and any incidental impurities.

B. A bearing material for a large engine comprising a four-layered structure having a backing metal such as steel, an Al or Al alloy (adhesive) layer, a bearing alloy layer comprising from 35 to 65% by weight of tin, 0.5 to 10% by weight bismuth, 0.1 to 1.5% by weight of copper and a surface layer which is lead, tin or an alloy thereof.

C. A bearing metal for a large engine comprising a three-layered structure having a backing metal such as steel, an Al or Al alloy (adhesive) layer and a bearing alloy layer comprising from 35 to 65% by weight of tin, 0.5 to 10% by weight of bismuth, 0.1 to 1.5% by weight of copper and 5% by weight or less of at least one of the elements manganese, nickel, silicon, silver, magnesium, antimony and/or zinc, the balance being Al and any incidental impurities.

D. A bearing metal for a large engine comprising a four-layered structure having a backing metal such as steel, and Al or Al alloy (adhesive) layer, a bearing alloy layer comprising from 35 to 65% by weight of tin, from 0.5 to 10% by weight of bismuth, 0.1 to 1.5% by weight of copper, and 5% by weight or less of at least one of the elements Mn, Ni, Si, Ag, Mg, Sb and/or Zn, the balance being Al and any incidental impurities and a surface layer which is lead, tin, or an alloy thereof.

The backing metal preferably has a thickness of from 1 to 20 mm, such as from 1 to 1.5 mm. The adhesive layer preferably has a thickness of from 0.01 to 0.15 mm, such as from 0.02 to 0.03 mm. Suitably the bearing alloy layer will have a thickness of from 0.2 to 3 mm, such as from 0.40 to 0.45 mm. If present, the surface layer will suitably have a thickness of from 1 to 30 pm, such a from 15 to 25 Zm. In preferred embodiments the total thickness of the bearing material is preferably from 1 to 2 mm.

Preferred components of the bearing materials, and their amounts, will now be given together with the reasons, where applicable, for the preferred ranges of components.

1. The backing metal (e.g. steel).

This is usually a well known steel, e.g. a general structural carbon steel in JIS (Japanese Industrial Standards).

2. Intermediate layer (or adhesive or bonding layer).

This is provided to try to enhance adhesive between the backing metal and the bearing alloy. It is preferably aluminium, such as pure aluminium. When the strength of the adhesive layer is important, the layer may be an aluminium alloy such as having from 0.1 to 2% by weight or less of at least one of the elements copper, silicon, manganese and/or zinc as an additive.

If the amount of the additive is less than 0.1% by weight it may be ineffective. On the other hand if it exceeds 2% by weight, the intermediate layer may become too embrittled to be practicable.

3. Bearing alloy layer.

(a) Content of tin: 35 to 65% by weight.

If the content of tin is less than 35% by weight, the anti-seizure property of the bearing and the embeddability of tin may become insufficient. On the other hand, if it exceeds 65% by weight, the fatigue resistance and the castability of the bearing alloy layer may become poor.

(b) Content of bismuth: 0.5 to 10% by weight (e.g. 3.5 to 10% by weight).

Bismuth can alloy with tin to improve the lubrication property of, and the compatibility of, the tin. Alloying bismuth and tin can increase the hardness of the layer of tin which may contribute to improvements in the fatigue resistance of the bearing alloy layer. Therefore, such alloying may improve the fatigue resistance of the bearing alloy without changing the strength of the Al matrix or deteriorating the initial compatibility of the bearing alloy layer.

If the content of bismuth is less than 0.5% by weight, then the addition of bismuth may be ineffective. On the other hand, if it exceeds 10% by weight, then the melting point of the bearing alloy may be reduced, which can cause problems from the production point of view.

(c) Content of copper: 0.1 to 1.5% by weight.

Copper can improve the fatigue resistance (one of the properties of the bearing material) of the bearing alloy and the adhesive strength between the bearing alloy layer and surface layer, if present. If the content of copper is less than 0.1% by weight, the copper may be ineffective. On the other hand, if it exceeds 1.5% by weight, the hardness of the bearing alloy might be increased excessively, which may deteriorate the initial compatibility of the bearing and the embeddability and ductility of the bearing alloy layer. This might make the production of the bearing alloy layer difficult.

(d) Content of at least one of Ni, Si, Ag, Mg, Mn, Sb and/or Zn: 5% by weight or less (e.g. from 0.3 to 3% by weight maximum of any one element).

These elements can be added in order to increase the mechanical strength of the Al matrix. If the content of one of the elements is more than 5% by weight, this may reduce the initial compatibility and the embeddability of the bearing alloy layer. The elements silicon and antimony are preferred; manganese and silver may often be included.

4. Surface layer (if present).

This is preferably a tin or lead, or an alloy thereof, for example an alloy comprising tin and lead and perhaps also Cu. In the latter case lead is suitably the major component, e.g. from 80 to 95% by weight lead, and perhaps from 1 to 5% by weight copper, the balance being any incidental impurities. This layer is suitably formed by a PVD technique, or electroplating, for example using a boron fluoride bath.

In order to improve the bonding between the bearing alloy layer and the surface layer, if present, an additional layer (e.g. nickel) may be formed between these layers, such as by electroplating.

A second aspect of the present invention relates to a method of manufacturing a bearing material, e.g. a bearing, the method comprising providing a backing layer and forming an aluminium or aluminium alloy adhesive layer underneath a bearing alloy layer which comprises from 35 to 65% by weight tin, from 0.5 to 10% by weight of bismuth, from 0.1 to 1.5% by weight of copper, the balance being aluminium and any incidental impurities.

The method preferably comprises first bonding together the adhesive layer and the bearing alloy layers, such as to form a laminate. The laminate may then be bonded to the backing layer. If necessary the resultant product may then be shaped, and a nickel layer may be formed.

The surface layer, if present, is suitably formed by a PVD technique or by electroplating, for example by using a boron fluoride bath.

Preferred features and characteristics of the second aspect are as for the first mutatis mutandis.

The invention will now be described by way of example, to illustrate but not limit the invention, with reference to the accompanying Examples and drawings, in which: 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 11 AND COMPARATIVE EXAMPLES 12 TO 17.

Table 1 shows the chemical compositions of the bearing alloy layers and surface layer where present, used in the eleven bearings (Examples 1 to 11) in accordance with the present invention. Table 2 shows the chemical compositions of six prior art bearing alloy layers (Comparative Examples 12 to 17) provided for comparison.

Suitable combinations of metal sheets having compositions as shown in Table 1 and 2, and a superimposed Al foil, were rolled through a rolling mill to produce a 1 mm thick composite laminate. The laminate was superimposed on a steel backing metal layer of 2 mm thickness and then roll pressure bonded to produce a 1.65 mm thick threelayered composite (i.e. a bearing alloy layer, an adhesive intermediate layer of Al, and a layer of steel backing metal). In the resultant bearing material, the thickness of the bearing alloy layer was 0.42 to 0.43 mm, the thickness of the Al intermediate layer was 0.02 to 0.03 mm and the thickness of the backing metal was 1.2 mm. . Each of the three-layered composites was press worked to 17 mm long bearing each having a semi-circular section with a diameter of 53 mm.For bearings with a surface layer the surface of the bearing was covered with a 20 m thick plating layer produced by electroplating in a known boron fluoride bath until the four-layered bearing was obtained. The bearings having the threelayered and four-layered structure were examined in seizure and fatigue tests. Fig. 1 shows a section of the three-layered bearing materials of the present invention while Fig. 2 shows a section of the four-layered bearing materials, also of the present invention. The steel metal is referenced by numeral 1, the Al adhesive layer by 2, the bearing alloy layer by 3, and the surface layer by 4.

Table 3 shows the conditions employed in the fatigue test for the bearing materials. Table 4 shows the conditions for the seizure test for the bearing materials, Table 5 for the results of the fatigue test while Table 6 shows the results of the seizure test.

From the Examples the bearing materials of the present invention demonstrate the following advantages.

In Table 5 it is shown that the fatigue resistance of each bearing material of the present invention was higher than the prior art bearing materials. It can thus be presumed that alloying bismuth with tin can increase the hardness of the tin layer thereby contributing to any improvement in the fatigue resistance. In the prior art bearings the fatigue resistance of an aluminium based bearing alloy could be reduced because of the high content of tin. However, the addition of bismuth in accordance with the bearing materials of the present invention may prevent such reductions in fatigue resistance.

Table 6 shows that the anti-seizure properties of each bearing material of the present invention was higher than the prior art bearing materials. It is thought that alloying of bismuth with tin may thus improve the lubricating characteristics of tin. The results of the fatigue and anti-seizure tests show that the fatigue resistance and anti-seizure properties of the bearing materials of the present invention are higher than those of the prior art bearing materials tested. The bearing materials of the present invention are suitable for bearings for large internal combustion engines that often require superior fatigue resistance and anti-seizure properties.

Table 1 Bearing Metals of the Invention

Chemical Composition of Bearing Alloy Layer Kind of No. (wt%) Product Sn Bi Cu Mn Ni Si Ag Mg Sb Zn Al Pb Sn Cu In 1 35 5.0 0.1 - - - - - - - balance balance 10 - 2 40 3.5 0.6 - - - - - - - balance - - - 3 40 5.0 0.4 - - 1.0 - - 0.3 - balance - - - 4 45 3.5 0.6 - 0.5 - - - - - balance - 100 - Bearings 5 45 5.0 0.4 - - - - 0.3 - - balance - - - of the 6 50 5.0 0.5 - - 1.5 1.0 - - 1.0 balance - - - Invention 7 50 5.0 0.5 0.3 - - - - - - balance - - - 8 55 10.0 0.8 - - 1.5 3.0 - 0.5 - balance - - - 9 65 7.0 1.2 - - - - - - - balance - - - 10 65 5.0 1.0 0.3 - 1.5 - - 0.3 - balance - - - 11 65 0.5 1.5 - - - - - - - balance balance 10 3 Table 2 Prior-art Bearing Metals

Chemical Chemical Composition of Bearing Alloy Layer Composition Kind of No. (wt%) of Surface Layer Product (wt%) Sn Bi Cu Mn Ni Si Ag Mg Sb Zn Al Pb Sn Cu In 12 55 - 0.3 - - - - - - - balance - - - 13 55 - 0.3 - - - - - - - balance balance 10 3 Prior art 14 55 - 0.4 - - 1.5 - - - - balance - - - Bearings 15 55 - 0.4 - - 1.5 - - - - balance - 100 - 16 55 - 1.0 - - - - - - - balance - 0 - 17 55 - 1.0 - - - - - - - balance balance 10 - Table 3 Conditions for Fatique Test

Dynamic Load Tester Item Magnitude etc. Unit Bearing Metal Size 53 dia. x 17 length mm X 1.5 thickness Revolutions 3000 rpm Velocity 8.3 m/s Lubricant oil SAY20 Temperature at oil inlet 60 C Oil supply pressure 3.0 kgf/cm2 Lubrication method feeding oil on shaft - Testing time 20 hr Material or shaft S55C (JIS) Shaft roughness 1.0 Rmax Vm Hardness of shaft 55 < HRC Method of Estimation When a ratio of the area of a fatigued part to the projected area of a bearing is 5% or more, the bearing is defined as fatigued.

Table 4 Conditions for Seizure Test

Dynamic Load Tester Item Magnitude etc. Unit 53 dia. x 13 length Bearing Metal Size x 1.5 thickness mm Revolutions 3000 rpm Velocity 10.0 m/s Lubricant oil SAE20 Temperature at oil inlet 98-102 C Oilfeed rate 12.5 cc/min Material for shaft S55C (JIS) Shaft roughness 1.0 > Rmax pm Testing Method A step-up method of stepping up a static load by 50 kgf/cm2 per 10 min.

Evaluation Method Seizure is judged when bearing back temperature rises over 2200C or electric current exceeds 20A.

Table 5 Fatique Test Results

Bearing Load (kGf/cm2) Kind of Sample Bearing Load (kgf/cm2) Products No .

Products No. 2! it 100 150 200 250 I I I I I 1 Bearings 5 of the Invention 6 7 l l ~ 8 X l l ~ 7 I I I 10 l l l 11 I I I I 12 ' T 1 13 T T Prior 14 = Beaarrtings 15 L I = 17 | St 1 * Black zones indicate that the test results varied within the range of the black zones. Table 6 Seizure Test Results

I I I Bearing Load (kgf/cm2) Kind of No.

850 No. 850 900 950 1000 1050 I I I I I I 1 I 1 01 1 1 ~ I I I I I I 7 2 T J I I I I 3 I 1 1 I 4 l 1 1 I C I Bearings 5 1 Of the l l l 1 I I Invention 6 I 7 l l 7 I 1 I 8 I I 1 .1.. 1- 1 E I 9 I 1 I 1 I .L I 10 I I I . z 11 ' 1 1 I I 1 I =t I ~ I 13 Prior Ir Art 15 Bearings l l 16 II I * Black zones indicate that the test results varied within the range of the black zones.

Claims

1. A bearing material comprising a backing metal and an Al or Al alloy adhesive layer underneath a bearing alloy layer comprising from 35 to 65% by weight tin, from 0.5 to 10% by weight bismuth, from 0.1 to 1.5% by weight of copper the balance being aluminium and any incidental impurities, and optionally a surface layer comprising lead, tin, or an alloy thereof.

2. A bearing material according to claim 1 wherein the bearing alloy comprises 5% by weight or less of 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 adhesive layer is bonded to the backing metal.

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

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

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

7. A bearing material as claimed in any preceding claim wherein the surface layer is present and has a thickness of from 15 to 25 Mm.

8. 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.

9. 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.

10. A bearing material as claimed in any preceding claim wherein the adhesive layer has a thickness of from 0.1 to 0.15 mm.

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

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

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

14. A bearing material as claimed in any preceding claim wherein the backing metal has a thickness of from 1 to 1.5 mm.

15. A bearing material as claimed in any preceding claim which has a total thickness of from 1 to 2 mm.

16. A bearing material as claimed in any preceding claim wherein the surface layer is tin.

17. A bearing material as claimed in any of claims 1 to 15 wherein the surface layer is a tin-lead alloy.

18. A bearing material as claimed in any of claims 1 to 15 wherein the surface layer is a tin-lead-copper alloy.

19. A bearing material as claimed in any preceding claim wherein the bismuth is present in the bearing alloy layer at from 3.5 to 10% by weight.

20. A bearing material as claimed in any preceding claim wherein the adhesive layer is aluminium.

21. A method of manufacturing a bearing material, the method comprising providing a backing metal and forming an aluminium or aluminium alloy adhesive layer underneath a bearing alloy layer which comprises from 35 to 65% by weight tin, from 0.5 to 10% by weight bismuth, from 0.1 to 1.5% by weight copper, the balance being aluminium and any incidental impurities, and optionally forming where necessary a surface layer which is lead, tin or an alloy thereof.

22. A method as claimed in claim 21 comprising: (a) bonding together the adhesive layer and bearing alloy layers to form a laminate; (b) bonding the so formed laminate to a backing layer; (c) optionallly 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.

23. A method as claimed in claim 22 wherein the surface layer is formed by electroplating.

24. A method as claimed in claim 22 or 23 wherein the surface layer is formed by electroplating in a boron fluoride bath.

25. A method as claimed in any of claims 21 to 24 for manufacturing a bearing material as claimed in any of claims 1 to 20.

26. A bearing material substantially as herein described with reference to Examples 1 to 11.

27. A method of manufacturing a bearing material substantially as herein described with reference to Examples 1 to 11.