WHITE METAL BABBITT FOR ROLLING MILL BUSHING

ALLIAGE DE METAL BLANC POUR BAGUE DE PALIER DE LAMINOIR

English Abstract

A tin based white metal alloy consisting essentially by weight of approximately 5.0%-9.0% antimony, approximately 3.0%-8.0% copper, approximately 0.1%-0.7% cobalt, and the balance tin.

French Abstract

L'invention concerne un alliage de métal blanc à base d'étain consistant essentiellement, en poids, en approximativement 5,0 %-9,0 % d'antimoine, approximativement 3,0 %-8,0 % de cuivre, approximativement 0,1 %-0,7 % de cobalt, le complément étant constitué par de l'étain.

Claims

CLAIMS
What is claimed is:
1. A tin based white metal alloy consisting essentially by weight of about
5.0% to
9.0% antimony, about 3.0 to about 8.0% copper, about 0.1% to about 0.7%
cobalt, and
the balance tin.
2. The alloy of claim 1 wherein the content of antimony is about 6.0% to
about 8.0%
by weight.
3. The alloy of claim 1 wherein the content of copper is about 6.0% to
about 7.0%
by weight.
4. The alloy of claim 1 wherein the content of cobalt is about 0.2% to
about 0.5% by
weight.
5. The alloy of claim 1 adapted for us use in heavy load bearings for the
steel
fabrication industry.
6 The alloy of claim 1 adapted for us in heavy load bearings for the use in
power
generation equipment.
7. The alloy in claim 1 adapted for us for spray and welded formed bearings
8 The alloy of claim 1 adapted for use for cast formed Babbitt type
bearings
9. A tin based white metal alloy consisting essentially by weight of about
6.0% to
about 8.0% antimony, about 6.0% to about 7.0% copper, about 0.2 to about 0.5%
cobalt,
and the balance tin.
10. The alloy of claim 9 adapted for use in at least one of: heavy load
bearings for the
steel fabrication industry; heavy load bearings for the use in power
generation equipment;
spray and welded formed bearings; or cast formed Babbit type bearings.
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Description

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WHITE METAL BABBITT FOR ROLLING MILL BUSHING
CROSS REFERENCE TO RELATED APPLICATION
This application claims benefit, under 35 U.S.C. 119(e), of U.S. Provisional
Application Serial No. 61/541,395, filed 30 September 2011, the entire
contents and
substance of which is hereby incorporated by reference.
BACKGROUND
1. Field
Embodiments and aspects of the present invention relate to tin based white
metal
alloys useful in various industrial applications, including the bushings of
rolling mill oil
film bearings.
2. Description of Related Art
The most prominent white metal alloy used in oil film bearings in the rolling
mill
field is described in ASTM B23 #2, (referred to here as ASTM #2) and is
comprised
primarily of tin, with antimony and copper, as alloying elements. ASTM #2 is
well
understood and is readily deposited onto bushing shells via centrifugal
casting, spray
deposition, or welding. Unfortunately, ASTM #2 has relatively low fatigue
resistance,
which limits load capacity of bearings made with this material.
Various versions of Nickel hardened white metal alloys have been used where
common versions are referred to as Tuftin. These alloys can be cast and
welded, but they
contain Nickel, which is a heavy metal that is undesirable for environmental
reasons.
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U.S. Patent No. 6,589,372 B1 (Roeingh et al.) discloses use of a known tin
based
white metal alloy consisting essentially of antimony, copper, zinc, silver,
and tin.
The alloy of Roeingh is suitable for centrifugal casting applications. But due
to the
brittleness of the zinc component, this alloy cannot be readily drawn into
wire for use in
spray and welding applications.
U.S. Patent No. 4,140,835 (Goddard) and U.K. Application No. 2146354 A
disclose cobalt as a component of tin based white metal alloys that also
include cadmium.
Cadmium is a known carcinogen that has been banned from most workplaces and
thus is
undesirable.
U.S. Patent Nos. 4,150,983 (Mori) and 5,512,242 (Tanake et al.) disclose
alloys in
which cobalt is employed along with chrome. The inclusion of chrome is
impractical as
it is not readily soluble under normal alloying conditions.
U.S. Patent No. 4,795,682 (Turner et al.) discloses a tin/cobalt alloy useful
as a
sacrificial coating designed to absorb particulates. Such coatings lack the
toughness
required for heavily loaded oil film bearing applications, and the disclosed
use of cobalt
at elevated percentage levels would inhibit the flow characteristics necessary
in a casting
or welding process.
SUMMARY
Briefly described, aspects of the present invention relate to a tin based
white metal
alloy that is universally useful in centrifugal casting, spraying, and welding
applications.
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Aspects of the present invention also relate to a tin based white metal alloy
having
the elevated strength and fatigue resistance required for use in heavily
loaded oil film
bearings of the type commonly found in the metals industry.
Aspects of the present invention further relate to a tin based white metal
alloy that
is low in toxicity and generally free from carcinogenic components, including
cadmium
and the like.
In one embodiment, aspects of the present invention may be achieved by
replacing zinc and silver components of the alloy disclosed in the above
referenced U.S.
Patent No. 6,589,372 B1 with cobalt in amounts ranging between about 0.1%-0.7%
by
weight, with amounts ranging between 0.2% and 0.5% being considered optimal.
DETAILED DESCRIPTION
To facilitate an understanding of embodiments, principles, and features of the
present invention, they are explained hereinafter with reference to
implementation in
illustrative embodiments. In particular, they are described in the context of
being a novel
and non-obvious tin-based white metal alloy.
Embodiments of the present invention, however, are not limited to use in the
described systems.
The components and materials described hereinafter as making up the various
embodiments are intended to be illustrative and not restrictive. Many suitable
components and materials that would perform the same or a similar function as
the
materials described herein are intended to be embraced within the scope of
embodiments
of the present invention.
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A tin based white metal alloy in accordance with the present invention
includes as
principal components tin, antimony, and copper, to which cobalt has been
added.
Addition of cobalt in amounts above approximately 0.7% by weight has been
found to
disadvantageously lower the fluidity of the resulting alloy. Thus, cobalt
additions of
between about O.1%-O.7% by weight have been found to be effective in achieving
the
above-stated objectives, with additions of between about 0.2%-0.5% by weight
being
optimal.
Tin based white metal alloys of the present invention consist essentially of
the
components listed in the following examples:
EXAMPLE I
Antimony 5.0-9.0% by weight
Copper 3.0-8.0% by weight
Cobalt 0.1-0.7% by weight
Tin Balance
EXAMPLE II
Antimony 6.0-8.0% by weight
Copper 3.0-8.0% by weight
Cobalt 0.1-0.7% by weight
Tin Balance
EXAMPLE III
Antimony 6.0-8.0% by weight
Copper 6.0-7.0% by weight
Cobalt 0.1-0.7% by weight
Tin Balance
EXAMPLE IV
Antimony 6.0-8.0% by weight
Copper 6.0-7.0% by weight
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Cobalt 0.2-0.5% by weight
Tin Balance
EXAMPLE V
Antimony 6.0-8.0% by weight
Copper 6.0-7.0% by weight
Cobalt 0.2-0.5% by weight
Tin Balance
The resulting alloys of the present invention may be centrifugally cast, and
may
also be drawn into wire for use in spraying or welding applications. Further,
alloys of the
present invention have the strength and fatigue resistance required for use in
heavily
loaded bearing applications, including the steel making industry applications,
while being
free of components that either are banned or otherwise detrimental.
Fatigue resistance of white metal alloys can be determined experimentally
through the use of tension/compression specimens that are cycled until
failure.
Laboratory test data comparing the alloy of the present invention with
commonly used
alloys in the field are illustrated in TABLE 1. Based on test data the fatigue
strength of
the alloy containing 0.3% to 0.5% cobalt has excellent fatigue resistance,
exceeding that
of other alloys commonly used in the rolling mill application. Test data shown
was
determined in accordance with ASTM E 466 with an applied load of 7,500 psi
(51.7
MPa) and test frequency of 10 Hz.

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Axial Fatigue Resistance of Various White Metal Alloys
18000 `."-
N
a 16000
-a
.c 14000
(7)
0-
a
c" 12000 _________
.41
r-
173'
co 10000 _________
uJ
2 8000 ___________
,a2- 6000
4000 __
2000 __
ASTM #2 Roeingh et al Tuftin Modified 0.3% - 0.5% Co
Alloy
Alloy
TABLE 1: Comparison of Fatigue Resistance, as measured in Cycles
to Failure in accordance with ASTM E 466, specimens stresses to 7,500 psi
(51.7 MPa)
While embodiments of the present invention have been disclosed in exemplary
forms, it will be apparent to those skilled in the art that many
modifications, additions,
and deletions can be made therein without departing from the spirit and scope
of the
invention and its equivalents, as set forth in the following claims.
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