U.S. patent application number 10/646208 was filed with the patent office on 2004-03-25 for sliding composition and sliding member.
This patent application is currently assigned to Daido Metal Company Ltd.. Invention is credited to Iwata, Hideki, Kashiyama, Kotaro, Niwa, Takahiro, Shindo, Takeshi.
Application Number | 20040058828 10/646208 |
Document ID | / |
Family ID | 27800611 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040058828 |
Kind Code |
A1 |
Iwata, Hideki ; et
al. |
March 25, 2004 |
Sliding composition and sliding member
Abstract
In prior art, the wear resistance and frictional properties of a
sliding member are improved by adding bismuth, an alkaline earth
metal salt or the like, but not lead, to a polytetrafluoroethylene
used as a base resin, in view of the undesirable influences of lead
on the environment. However, a further improved wear resistance at
a high PV value has been desirable. In the present invention, a
sliding member having excellent wear resistance and frictional
properties even when used at a high PV value can be obtained by
using a thermosetting resin as a base resin in a proportion of 50
to 80 vol % and adding thereto a PTFE with a molecular weight of
3,000,000 or more in a proportion of 10 to 40 vol % and bismuth
and/or a bismuth alloy in a proportion of 1 to 20 vol %.
Inventors: |
Iwata, Hideki; (Inuyama-Shi,
JP) ; Niwa, Takahiro; (Inuyama-Shi, JP) ;
Shindo, Takeshi; (Inuyama-Shi, JP) ; Kashiyama,
Kotaro; (Inuyama-Shi, JP) |
Correspondence
Address: |
RADER, FISHMAN & GRAUER PLLC
39533 WOODWARD AVENUE
SUITE 140
BLOOMFIELD HILLS
MI
48304-0610
US
|
Assignee: |
Daido Metal Company Ltd.
|
Family ID: |
27800611 |
Appl. No.: |
10/646208 |
Filed: |
August 22, 2003 |
Current U.S.
Class: |
508/104 ;
508/106 |
Current CPC
Class: |
C10M 111/04 20130101;
C10M 2201/05 20130101; C10M 2213/06 20130101; C10N 2020/04
20130101; C10N 2010/10 20130101; C10N 2050/14 20200501; C10N
2020/01 20200501; F16C 2208/80 20130101; C10N 2040/06 20130101;
C10M 2201/084 20130101; C10N 2030/06 20130101; C10M 2201/066
20130101; C10N 2010/04 20130101; F16C 33/201 20130101; C10M
2213/062 20130101; C10M 125/02 20130101 |
Class at
Publication: |
508/104 ;
508/106 |
International
Class: |
C10M 161/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 24, 2002 |
JP |
2002-277290 |
Claims
What is claimed as new and desired to be protected by Letters
Patent of the United States is:
1. A sliding composition comprising 50 to 80 vol % of a
thermosetting resin, 10 to 40 vol % of a polytetrafluoroethylene
having a molecular weight of 3,000,000 or more and 1 to 20 vol % of
bismuth and/or a bismuth alloy.
2. A sliding composition comprising 50 to 80 vol % of a
thermosetting resin, 10 to 40 vol % of a polytetrafluoroethylene
having a molecular weight of 3,000,000 or more and 1 to 20 vol % of
an alkaline earth metal salt.
3. A sliding composition comprising 50 to 80 vol % of a
thermosetting resin, 10 to 40 vol % of a polytetrafluoroethylene
having a molecular weight of 3,000,000 or more and 1 to 20 vol % in
total of bismuth or a bismuth alloy, or both and an alkaline earth
metal salt.
4. A sliding composition according to claim 1, which further
comprises 1 to 30 vol % of a solid lubricant.
5. A sliding composition according to claim 2, which further
comprises 1 to 30 vol % of a solid lubricant.
6. A sliding composition according to claim 3, which further
comprises 1 to 30 vol % of a solid lubricant.
7. A sliding member obtained by coating a substrate with a sliding
composition according to claim 1.
8. A sliding member obtained by coating a substrate with a sliding
composition according to claim 2.
9. A sliding member obtained by coating a substrate with a sliding
composition according to claim 3.
10. A sliding member obtained by coating a substrate with a sliding
composition according to claim 4.
11. A sliding member obtained by coating a substrate with a sliding
composition according to claim 5.
12. A sliding member obtained by coating a substrate with a sliding
composition according to claim 6.
13. A sliding member obtained by coating a porous layer formed on a
substrate with a sliding composition according to claim 1 by
impregnation.
14. A sliding member obtained by coating a porous layer formed on a
substrate with a sliding composition according to claim 2 by
impregnation.
15. A sliding member obtained by coating a porous layer formed on a
substrate with a sliding composition according to claim 3 by
impregnation.
16. A sliding member obtained by coating a porous layer formed on a
substrate with a sliding composition according to claim 4 by
impregnation.
17. A sliding member obtained by coating a porous layer formed on a
substrate with a sliding composition according to claim 5 by
impregnation.
18. A sliding member obtained by coating a porous layer formed on a
substrate with a sliding composition according to claim 6 by
impregnation.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority based on Japanese Patent
Application No. 2002-277290, filed Sep. 24, 2002, the entirety of
which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a sliding composition and a
sliding member which do not contain lead for the purpose of
reducing influences on the environment.
[0003] Polytetrafluoroethylenes (hereinafter referred to as PTFEs)
excellent in self-lubricating properties have been used in sliding
members for dry bearing and have been tried to be improved in wear
resistance by addition of lead or the like (see, for example,
JP-B-39-16950 (pp. 1-2)). When PTFE containing lead added thereto
is used in a sliding member, it is transferred to a shaft supported
by the sliding member because lead is effective in forming a film
by the transfer. Thus, the PTFE forms the film on the shaft.
Therefore, the sliding of the sliding member and the shaft on each
other becomes the sliding of their PTFE films on each other,
resulting in the following effect: the sliding member is excellent
in frictional properties particularly when the sliding is conducted
without lubrication. However, since lead has serious influences on
the environment, bismuth (see, for example, JP-A-2001-221231 (p.
1)), barium sulfate (see, for example, JP-A-2002-20568 (pp. 1-2) or
the like has been added as a substitute for lead.
[0004] However, although a sliding member obtained by adding
bismuth (JP-A-2001-221231) or barium sulfate (JP-A-2002-20568) to
PTFE used as a base resin possesses improved coefficient of
friction and wear resistance, a further improved wear resistance at
a high PV value has been desirable.
BRIEF SUMMARY OF THE INVENTION
[0005] The present invention was made in view of the above
situation, and an object thereof is to further improve the wear
resistance and frictional properties at a high PV value of a
sliding composition and a sliding member.
[0006] For the achievement of the above object, the present
invention provides a sliding composition comprising 50 to 80 vol %
of a thermosetting resin, 10 to 40 vol % of a
polytetrafluoroethylene having a molecular weight of 3,000,000 or
more and 1 to 20 vol % of bismuth and/or a bismuth alloy; and a
sliding member obtained by the use of said composition.
[0007] When the sliding composition has this make-up, the heat
resistance, wear resistance and mechanical strength of the sliding
member can be improved by the use of a thermosetting resin with a
high mechanical strength as the base resin of the sliding
composition. When the proportion of the thermosetting resin is less
than 50 vol %, no sufficient mechanical strength can be attained,
so that no sufficient wear resistance can be expected. When the
proportion is more than 80 vol %, the effect of the addition of
bismuth, an alkaline earth metal salt, PTFE and the like described
hereinafter is lessened, so that no desirable frictional properties
can be attained. The thermosetting resin includes phenolic resins,
epoxy resins, polyimide resins, polyamide-imide resins, etc.
[0008] The adjustment of the molecular weight of the PTFE to
3,000,000 or more improves the wear resistance of the sliding
composition and permits formation of a firm film by the transfer of
the composition on a shaft supported by the sliding member. When
the proportion of the PTFE ranges 10 to 40 vol % based on the total
volume of the sliding composition, the formation of a firm film on
the shaft by the transfer of the composition becomes possible,
resulting in improved frictional properties. When the proportion is
less then 10 vol %, no satisfactory frictional properties can be
expected. When the proportion is more than 40 vol %, no desirable
wear resistance can be attained.
[0009] Bismuth and the bismuth alloy have the effect of forming a
film by the transfer of the composition on the shaft supported by
the sliding member, so that they contribute to the improvement of
the wear resistance when incorporated in a dispersed state into the
resins in the sliding composition. The bismuth alloy is, for
example, that obtained by incorporating silver, tin, zinc or indium
into bismuth. A sliding composition containing the bismuth alloy as
an additive is harder than a sliding composition containing pure
bismuth as an additive, and hence has a further improved wear
resistance. The content of such a metal added to bismuth is
preferably 0.5 to 30 mass %, more preferably 5 to 15 mass %, based
on the total mass of bismuth. When the proportion of bismuth and/or
the bismuth alloy is less than 1 vol % based on the total volume of
the sliding composition, no satisfactory frictional wear properties
can be expected. When the proportion is more than 20 vol %, the
wear resistance is gradually deteriorated.
[0010] The present invention also provides a sliding composition
comprising 50 to 80 vol % of a thermosetting resin, 10 to 40 vol %
of a polytetrafluoroethylene having a molecular weight of 3,000,000
or more and 1 to 20 vol % of alkaline earth metal salt; and a
sliding member obtained by the use of said composition.
[0011] When the sliding composition has this make-up, the same
effects as those described above can be obtained because the
alkaline earth metal salt has the effect of forming a film by the
transfer of the composition on a shaft supported by the sliding
member. When the proportion of the alkaline earth metal salt is
less than 1 vol % based on the total volume of the sliding
composition, no satisfactory frictional wear properties can be
expected. When the proportion is more than 20 vol %, the wear
resistance is gradually deteriorated. The alkaline earth metal salt
includes, for example, phosphates, carbonates, silicates and
sulfates, such as calcium phosphate, calcium carbonate, magnesium
silicate, barium sulfate, etc. The alkaline earth metal salt in the
present specification refers to Be, Mg, Ca, Sr, Ba or Ra.
[0012] Furthermore, the present invention provides a sliding
composition comprising 50 to 80 vol % of a thermosetting resin, 10
to 40 vol % of a polytetrafluoroethylene having a molecular weight
of 3,000,000 or more and 1 to 20 vol % in total of bismuth or a
bismuth alloy, or both and an alkaline earth metal salt; and a
sliding member obtained by the use of said composition.
[0013] When the sliding composition has this make-up, the same
effects as above can be obtained, namely, the sliding member is
excellent in the heat resistance, wear resistance, chemical
resistance, frictional properties and strength. Moreover, the
sliding member possesses improved frictional wear properties not
only when used without lubrication but also when used with
lubrication. Therefore, excellent sliding becomes possible owing to
both these effects and the above-mentioned effects. The total
adding amount of bismuth or the bismuth alloy, or both and the
alkaline earth metal salt is preferably 1 to 20 vol % based on the
total volume of the sliding composition.
[0014] In the present invention, each of the sliding compositions
described above may further comprise 1 to 30 vol % of a solid
lubricant.
[0015] When this making-up is employed, the resulting sliding
composition can have more excellent frictional properties and wear
resistance in either its use without lubrication or its use with
lubrication. The proportion of the solid lubricant is preferably 1
to 30 vol % based on the total volume of the sliding composition.
The solid lubricant includes graphite, molybdenum disulfide,
tungsten disulfide, boron nitride, etc.
[0016] Each of the sliding compositions described above can be used
for producing a sliding member by coating a substrate with the
sliding composition. More preferably, a sliding member is produced
by forming a porous layer on a substrate and coating the porous
layer with said sliding composition by impregnation. When the
sliding member is thus produced, the adhesion between the sliding
composition and the substrate is firm, so that the sliding member
has a high strength.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The present invention will now be described, by way of
example, with reference to the accompanying drawings, in which:
[0018] FIG. 1 is a cross-sectional view of a sliding member which
shows one embodiment of the present invention.
[0019] In FIG. 1, numeral 1 denotes a sliding member, numeral 2 a
plated copper film, numeral 3 a backing metal layer, numeral 4 a
porous sintered metal layer, and numeral 5 a sliding
composition.
DETAILED DESCRIPTION OF THE INVENTION
[0020] One embodiment of the present invention is explained below
with reference to FIG. 1.
[0021] A section of a sliding member 1 is shown in FIG. 1. As shown
in FIG. 1, the sliding member 1 is composed of a substrate, i.e., a
backing metal layer 3 composed of a steel (low-carbon steel for
common structure) plate and having a plated copper film 2 formed on
the surface, and a sliding composition 5 coating the substrate
through a porous sintered metal layer 4 of powder of a copper-based
alloy by impregnation of this layer with the composition. The
porous sintered metal layer 4 is joined in a powder state to the
plated copper film and hence has numerous voids in its inside and
surface portion.
[0022] Next, a process for producing the sliding member 1 shown in
FIG. 1 is explained below.
[0023] First, powder of a copper-based alloy is spread on a backing
metal layer 3 composed of a steel (low-carbon steel for common
structure) plate of 1.2 mm thick and having a plated copper film
formed on the surface, to a thickness of 0.3 mm. The backing layer
3 thus treated is heated at a temperature of 750 to 900.degree. C.
in a reducing atmosphere to sinter the copper-based alloy powder,
whereby a porous sintered metal layer 4 is obtained on the backing
metal layer 3.
[0024] On the other hand, a sliding composition 5 is obtained in
the form of a varnish by mixing the components shown in Table 1 in
the proportions shown in Table 1. The porous sintered metal layer 4
on the aforesaid backing metal layer 3 is coated with the
varnish-form sliding composition 5 by impregnation, after which the
varnish-form sliding composition 5 is cured at a temperature of 150
to 250.degree. C.
[0025] In order to verify the effect of the present invention,
tests were carried out by the use of a thrust tester. In the tests
for verification, the coefficient of friction and depth of wear of
inventive sliding members and comparative sliding members were
measured. Table 1 shows the results of the tests carried out.
[0026] Table 2 shows the test conditions. As to a criterion for
judging the occurrence of seizure in the tests, it was judged by
either a torque of more than 5 Kgf.multidot.m (49N.multidot.m) or a
depth of wear of more than 50 .mu.m.
1 TABLE 1 Conditions 1 Conditions 2 Coefficient Coefficient Sample
No. Composition (vol %) of friction depth of wear of friction depth
of wear Comparative sliding member (1) PF resin Seizure (torque
over) Seizure (torque over) (2) PF resin + 20 PTFE (1) 0.21 9 .mu.m
Seizure (torque over) (3) PF resin + 20 PTFE (2) 0.23 14 .mu.m
Seizure (torque over) (4) PF resin + 20 barium sulfate 0.23 13
.mu.m Seizure (torque over) (5) PF resin + 40 graphite 0.22 15
.mu.m Seizure (torque over) (6) PTFE + 20 lead 0.13 21 .mu.m
Seizure (torque over) + marked wear (7) PTFE + 20 bismuth 0.12 25
.mu.m Seizure (torque over) + marked wear (8) PTFE + 20 barium
sulfate 0.18 30 .mu.m Seizure (torque over) + marked wear (9) PTFE
+ 10 barium sulfate + 0.15 23 .mu.m Seizure (torque over) + 5
graphite + 5 molybdenum marked wear disulfide Inventive sliding
member (1) PF resin + 20 PTFE (1) + 0.14 11 .mu.m 0.10 23 .mu.m 10
bismuth (2) PF resin + 20 PTFE (1) + 0.16 15 .mu.m 0.11 30 .mu.m 10
barium sulfate (3) PF resin + 20 PTFE (1) + 0.15 14 .mu.m 0.11 28
.mu.m 5 bismuth + 5 calcium carbonate (4) PF resin + 20 PTFE (1) +
0.12 15 .mu.m 0.10 29 .mu.m 10 barium sulfate + 5 graphite + 5
molybdenum disulfide (5) PF resin + 20 PTFE (1) + 5 0.11 15 .mu.m
0.10 27 .mu.m bismuth + 5 barium sulfate + 5 graphite + 5
molybdenum disulfide
[0027]
2 TABLE 2 Conditions 1 Speed 6 m/min Load 5 MPa Lubrication No
lubrication Test time 4 hrs Material for a shaft supported by a
S55C sliding member Roughness Ry 2-3 .mu.m Hardness HV 200-300
Conditions 2 Speed 12 m/min Load 10 MPa Lubrication No lubrication
Test time 4 hrs Material for a shaft supported by a S55C sliding
member Roughness Ry 2-3 .mu.m Hardness HV 200-300
[0028] The test results are investigated. Inventive sliding members
(1) to (5) exhibited good sliding properties without seizure
(torque over or a depth of wear of more than 50 .mu.m) under both
conditions 1 and conditions 2.
[0029] On the other hand, comparative sliding member (1) was
obtained by using only a PF resin (a phenolic resin) and hence
seized under both conditions 1 and conditions 2. Comparative
sliding members (2) to (5) were obtained by using a thermosetting
resin as a base material but seized under conditions 2. Comparative
sliding members (6) to (9) seized and showed a large depth of wear
under conditions 2 because their base resin was PTFE.
[0030] The materials used in the experiments are as follows. The PF
resin is "MILEX XL-325M" manufactured by Mitsui Chemicals Inc. The
PTFE powders are the following two powders; PTFE (1): "Teflon Fine
Powder 6-J (molecular weight 3,000,000 or more, and average
particle size 470 .mu.m)" manufactured by Mitsui Dupont
Fluorochemicals Co., Ltd., and PTFE (2): "Lublon L-2 (molecular
weight 600,000 or less, and average particle size 2 .mu.m)"
manufactured by Daikin Industries, Ltd. The barium sulfate is
"BMH-100" manufactured by Sakai Chemical Industry Co., Ltd.
[0031] The average particle size of PTFE particles is preferably
300 to 600 .mu.m. When the average particle size is as large as 300
to 600 .mu.m, PTFE particles are made into fiber during mixing with
a thermosetting resin and the like to have a large specific surface
area. Therefore, the PTFE particles are distributed widely at a
high density in the surface of the sliding composition 5, so that
the sliding composition 5 has chemical resistance, heat resistance
and excellent frictional properties owing to the excellent
self-lubricating properties of the PTFE particles.
[0032] The sliding member 1 of the present invention comprising the
porous sintered metal layer 4 on the backing metal layer 3 and the
sliding composition 5 coating the porous sintered metal layer 4 by
impregnation as described above is produced as a bearing by
processing into a semi-cylinder or a cylinder.
[0033] Needless to say, the sliding member 1 of the present
invention can be used not only without lubrication but also with
lubrication and exhibits at both a high speed and a low speed.
* * * * *