P2056PCT
DESCRIPTION
ANNULAR SEAL MEMBER FOR USE IN SPHERICAL EXHAUST PIPE JOINT,
AND PRODUCTION METHOD THEREOF
TECHNICAL FIELD
This invention relates to an annular seal member for
use in a spherical exhaust pipe joint which is adapted as an
exhaust gas seal member for a spherical joint for use in
connecting an exhaust pipe to be connected to an engine of an
automobile or a like vehicle.
BACKGROUND ART
An exhaust gas to be exhausted from an engine of an
automobile or a two-wheeled motor vehicle is processed by a
catalyst, and then, is exhausted out into the air through an
exhaust pipe.
In the case of an automobile, for instance, an exhaust
pipe extending from an exhaust section of an engine to a
muffler section provided at a rear portion of a vehicle body is
fixed to a bottom portion of the vehicle body. The exhaust
pipe in the fixed state is oscillated and periodically exerted
with a flexure load while being subjected to an inertia force
resulting from oscillations due to a torque reaction of the
engine, or accelerations/decelerations exerted thereto in
driving the automobile. Such a flexure load may cause fatigue
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or breakage of the exhaust pipe.
An exhaust pipe equipped with a movable spherical joint
100 as shown in FIG. 14 is known as a measure for solving the
above drawback.
In FIG. 14, 111 denotes an annular seal member, 110
denotes an upstream exhaust pipe to be connected to an
unillustrated engine section, 120 denotes a downstream exhaust
pipe which is opposed to the upstream exhaust pipe 110 and is
connected to an unillustrated muffler section, and 130 denotes
a flared seal seat having a partially concave spherical surface.
A flange portion 140 is formed on an outer peripheral
surface of the upstream exhaust pipe 110, except for a portion
corresponding to a pipe end portion 101 for engaging with the
annular seal body 111.
The flared seal seat 130 having the partially concave
spherical surface is formed on a distal portion of the
downstream exhaust pipe 120. The downstream exhaust pipe 120
further includes a flange portion 150 which is integrally
formed with the seal seat 130.
The annular seal member 111 is fittingly seated on a
cylindrical inner surface 1 at the pipe end portion 101 in a
state that the flange portion 140 is abutted against an annular
end surface 3 formed on a large-diameter side of the pipe end
portion 101. The downstream exhaust pipe 120 is arranged in
such a manner that a partially convex spherical surface 2
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serving as a sliding surface of the annular seal member 111 is
brought into plane contact with the partially concave spherical
surface of the seal seat 130.
The upstream exhaust pipe 110 and the downstream exhaust
pipe 120 are connected with each other by threadably engaging a
male threaded portion of a bolt 160 extending through the
flange portion 150 in a female threaded portion of the flange
portion 140. The bolt 160 extends in a coil spring 170. By
threadably engaging and screwing the male threaded portion and
the female threaded portion, the downstream exhaust pipe 120 is
urged toward the upstream exhaust pipe 110 by a spring force.
The spring force allows a relative angular displacement in
oscillations of the exhaust pipe, thereby suppressing fatigue
and breakage of the exhaust pipe resulting from oscillations of
the exhaust pipe.
An example of the seal member to be used in the
spherical joint is, for instance, disclosed in the below-
mentioned Patent Document 1. Patent Document 1 discloses an
annular seal member which comprises a compressed wire mesh and
graphite filled in the wire mesh, and which has an outer
peripheral surface with a partially convex spherical
configuration.
In use of the seal member, however, when the spherical
joint is oscillated, abnormal noise may be generated.
Conceivably, generation of the abnormal noise is attributable
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to adhesion of the graphite filled in the seal member onto the
seal seat, and abrasion of the adhered graphite against the
graphite filled in the seal member.
Based on the above finding, the below-mentioned Patent
Document 2 discloses a seal member having an arrangement that a
lubricating composition comprising a quadrivalent ethylene
fluoride resin, or a copolymer of quadrivalent ethylene
fluoride and sexivalent propylene fluoride is coated on a
surface of the seal member produced by compression molding a
heat-resistant material including expansive graphite, mica,
asbestos together with a reinforcing material including a
reticular substance. The lubricating composition coated on the
surface of the seal member prevents the expansive graphite and
the like from adhering onto the seal seat, thereby reducing
friction noise.
In the above arrangement, however, if the seal member is
used in a high temperature condition of e.g. 300 ° C or more,
the lubricating composition may be melted or decomposed. As a
result, a sufficient effect of reducing the friction noise may
not be obtained.
In an attempt to solve the above drawback, the below-
mentioned Patent Document 3 discloses a spherical zone seal
body for use in a spherical exhaust pipe joint. The spherical
zone seal body is a compression molded product made of a
reinforcing member including a reticular substance, and a heat-
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resistant material including expansive graphite, and is formed
with a partially convex spherical portion on an outer
peripheral surface thereof. Patent Document 3 recites that a
lubricating layer comprising boron nitride, and at least one
selected from the group consisting of alumina and silica is
formed on a surface of the partially convex spherical portion.
The lubricating layer recited in Patent Document 3
includes boron nitride as a main ingredient. The boron nitride
is a lubricating material which is less likely to be melted or
decomposed at a high temperature. However, the lubricating
layer including boron nitride as a single constituent is
inferior in its adhesion onto the surface of the partially
convex spherical portion. The invention recited in Patent
Document 3 discloses means for improving the adhesion by adding
at least one selected from the group consisting of alumina and
silica, in addition to the boron nitride.
Even with use of the lubricating layer made of the
lubricating composition including at least one selected from
the group consisting of alumina and silica, in addition to the
boron nitride, however, the adhesion is insufficient. In the
case where a seal body formed with the lubricating layer having
such an insufficient adhesion is incorporated in a spherical
joint, the lubricating layer may be exfoliated by abrasion due
to a friction of the sliding surface of the seal body against
the surface of the seal seat resulting from oscillations of the
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spherical joint. As a result, the effect of reducing friction
noise lasts only for a short time.
Patent Document 3 also recites a seal body formed with a
lubricating layer including a polytetrafluoroethylene resin, in
addition to the lubricating composition comprising boron
nitride, and at least one selected from the group consisting of
alumina and silica in order to enhance the adhesion. The
polytetrafluoroethylene resin exhibits superior lubricity owing
to its low friction property, and serves as a binder of the
boron nitride or a like compound.
If the seal body formed with the lubricating layer is
used in a spherical exhaust pipe joint, an effect of reducing
friction noise can be obtained at low temperature ambient.
However, in use of the seal body at high temperature ambient
corresponding to a condition where the surface temperature of
the partially convex spherical portion is 300 ° C or exceeds
400 °C, the polytetrafluoroethylene resin may be melted or
decomposed, thereby losing the function as the binder. As a
result, the adhesion of the lubricating layer comprising boron
nitride may be degraded, thereby resulting in exfoliation of
the lubricating layer.
The inventors have found that the friction noise that is
generated when the lubricating layer is exfoliated is of a kind
of noise that is generated by friction of metals.
The inventors have conceived that the friction noise
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similar to the noise resulting from friction of metals is
generated for the following reason. Specifically, exfoliation
of the lubricating layer causes direct friction of the wire
mesh of the seal body against the seal seat, or friction of
metallic powders generated by abrasion of the wire mesh against
the seal seat, which resultantly causes the friction noise.
As a result of the examination, the inventors found that
improving lubricity or abrasion resistance of a wire mesh which
is exposed from the sliding surface enables to suppress the
friction noise similar to the noise caused by friction of
metals, and achieved the invention.
Patent Document 1: Japanese Unexamined Patent
Publication No. 54-76759
Patent Document 2: Japanese Unexamined Patent
Publication No. 58-24620
Patent Document 3: Japanese Patent No. 3139179
DISCLOSURE OF THE INVENTION
An aspect of the invention is directed to an annular
seal member for use in a spherical exhaust pipe joint
provided with, on an inner peripheral surface and an outer
peripheral surface thereof, a sliding surface for slidably
moving the spherical exhaust pipe joint. The annular seal
member includes an annular mesh structural body having a
compressed wire mesh; and a heat-resistant sheet member which
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is compressed to be integrally formed with the compressed
wire mesh. At least a part of the compressed wire mesh which
is exposed from the sliding surface has a dispersive plating
layer in which at least one kind of particles selected from
the group consisting of fluorine resin particles, boron
nitride particles, molybdenum disulfide particles, and
silicon carbide particles are dispersed.
Another aspect of the invention is directed to a method
for producing an annular seal member for use in a spherical
exhaust pipe joint. The method comprises: a convolute member
forming step of superposing, one on top of the other, a band-
shaped heat-resistant seal sheet, and a dispersive-plated
zone wire mesh having a dispersive plating layer in which at
least one kind of particles selected from the group
consisting of fluorine resin particles, boron nitride
particles, molybdenum disulfide particles, and silicon
carbide particles are dispersed to form a laminated member,
and of winding the laminated member into a convolute member;
a convolute member mounting step of mounting the convolute
member in a bottomed annular die provided with a solid
cylindrical core in the middle part of the bottomed annular
die; and a compression molding step of compression molding
the convolute member in a direction of a center axis of the
convolute member.
Yet another aspect of the invention is directed to a
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method for producing an annular seal member for use in a
spherical exhaust pipe joint. The method comprises: a
convolute member forming step of superposing a non-
dispersive-plated zone wire mesh and a band-shaped heat-
resistant seal sheet one on top of the other to form a
laminated member, and of winding the laminated member into a
convolute member; a first compression molding step of
mounting the convolute member in a bottomed annular die
provided with a solid cylindrical core in the middle part of
the bottomed annular die, and of compression molding the
convolute member in a direction of a center axis of the
convolute member to form an annular seal member perform; and
a second compression molding step of placing a dispersive-
plated wire mesh in which at least one kind of particles
selected from the group consisting of fluorine resin
particles, boron nitride particles, molybdenum disulfide
particles, and silicon carbide particles are dispersed over
the annular seal member perform in such a manner that at
least one surface selected from the group consisting of an
outer peripheral surface and an inner peripheral surface of
the annular seal member perform is covered by the dispersive-
plated wire mesh, and of compression molding the dispersive-
plated wire mesh and the annular seal member perform together.
These and other objects, features, aspects, and
advantages of the present invention will become more apparent
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upon reading of the following detailed description along with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram showing an example of a
configuration of an annular seal member in a first embodiment
of the invention.
FIG. 2 is a partially sectional view showing the
configuration of the annular seal member in the first
embodiment of the invention.
FIG. 3 is a diagram showing an example of a method for
producing a zone wire mesh to be used in a production process
of the annular seal member in the first embodiment of the
invention.
FIG. 4 is a diagram showing an example of a laminated
member to be used in the production process of the annular seal
member in the first embodiment of the invention.
FIG. 5 is a top plan view showing an example of a
convolute member to be used in the production process of the
annular seal member in the first embodiment of the invention.
FIG. 6A is a cross-sectional view of a punching section
of a compression molding die to be used in producing the
annular seal member of the invention.
FIG. 6B is a cross-sectional view of the compression
molding die to be used in producing the annular seal member of
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the invention.
FIGS. 7A through 7C are diagrams showing an example of a
production process of an annular seal member in a second
embodiment of the invention, wherein FIG. 7A shows a spherical
zone seal member preform, FIG. 7B shows a dispersive-plated
wire mesh, and FIG. 7C shows the spherical zone seal member
preform covered with the dispersive-plated wire mesh.
FIG. 8 is a diagram showing an example of a
configuration of an annular seal member in a third embodiment
of the invention.
FIG. 9 is a cross-sectional view of a spherical exhaust
pipe joint incorporated with the annular seal member in the
third embodiment of the invention.
FIG. 10 is a partially sectional view of a spherical
exhaust pipe joint unit for use in assessing examples.
FIG. 11 is a diagram showing an arrangement of an
apparatus for assessing friction noise generated from the
examples.
FIG. 12 is a graph showing frequency dependencies of
sound pressure level at 500 °C, based on an assessment result
on friction noise generated from the examples.
FIG. 13 is a graph showing frequency dependencies of
sound pressure level at 25 °C, based on an assessment result on
friction noise generated from the examples.
FIG. 14 is a partially sectional view showing a
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spherical exhaust pipe joint incorporated with a conventional
spherical zone annular seal body.
FIG. 15 is a partially sectional view showing a
spherical exhaust pipe joint incorporated with the spherical
zone annular seal member shown in FIG. 1.
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment)
A first embodiment of an annular seal member according
to the invention is described referring to FIGS. 1 and 2.
FIG. 1 is a diagram showing a spherical zone annular
seal member 10 provided with an outer peripheral surface
shaped into a partially convex spherical configuration, as
the first embodiment of the annular seal member of the
invention. FIG. 2 is a partially section view of FIG. 1.
Referring to FIGS. 1 and 2, 1 denotes a cylindrical
inner surface for defining a through-hole 50, 2 denotes a
partially convex spherical surface, 3 denotes an annular end
surface formed on a large-diameter side of the partially
convex spherical surface 2, and 4 denotes an annular end
surface formed on a small-diameter side of the partially
convex spherical surface 2. The annular seal member 10 has
its configuration defined by the respective surfaces
constituting the annular seal member 10. The annular seal
member 10 comprises an annular mesh structural body including
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a compressed wire mesh 5, and a heat-resistant seal member 6
which contains expansive graphite and the like, and is
integrally compressed with the annular mesh structural body.
The annular seal member 10 has such a configuration
that the partially convex spherical surface 2 serves as a
sliding surface, and is brought into plane contact with a
surface of a flared seal seat having a partially concave
spherical surface, which is formed on a spherical exhaust
pipe joint to be described later.
The wire mesh exposing from the partially convex
spherical surface 2 of the annular seal member 10 is formed
with a dispersive plating layer in which at least one kind of
particles selected from the group consisting of fluorine
resin particles, boron nitride particles, molybdenum
disulfide particles, and silicon carbide particles are
dispersed.
An exemplified method for producing the annular seal
member 10 is described in the following.
The heat-resistant seal member for use in producing the
annular seal member 10 is made of a material including, as a
main ingredient, an inorganic material having a heat
resistance and gas sealability such as expansive graphite or
mica. A heat-resistant seal sheet for use in the annular seal
member production method is a processed sheet having a
thickness of about 0.1 to 1 mm. A sheet having a high heat
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resistance e.g. a sheet whose oxidation start temperature is
800 ° C or more is particularly preferred. Preferred examples
of the sheet are: expansive graphite sheets such as an
expansive graphite sheet PF-G3 (thickness: 0.4 mm, product of
Toyo Carbon Co. Ltd.), and an expansive graphite sheet APX-2
(thickness: 0.38 mm, product of SGL); and a mica sheet TYPE
36.006 (product of Electro Isola). Among them, a heat-
resistive expansive graphite sheet is preferably used in the
aspect of its superior gas sealability and heat resistance.
The zone wire mesh to be used in production of the
annular seal member 10 can be produced by the following
process.
As shown in FIG. 3, a cylindrical wire mesh 7 obtained
by weaving or knitting a fine metal wire having a diameter Φ
from about 0.10 to 0.35 mm into a cylindrical shape is passed
between a pair of rollers 8 and 9, and shaped into a wire
mesh having a predetermined width W, and then cut into a
predetermined length L, whereby a zone wire mesh 15 is
produced.
Examples of the fine metal wire are stainless steel
wires made of austenite stainless steel such as SUS304 or
SUS316, or made of ferrite stainless steel such as SUS430;
iron-based wires (JIS-G-3532) or zinc-plated iron wires (JIS-
G-3547); and fine metal wires made of copper alloys such as
copper-nickel alloy (cupro-nickel), copper-nickel-zinc alloy
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(nickel silver), brass, or beryllium copper.
The wire mesh 5 is exposed from the outer peripheral
surface of the annular seal member 10, serving as a sliding
surface. On the surface of the wire mesh 5 which is exposed
from the sliding surface, there is formed a dispersive
plating layer, in which at least one kind of particles
selected from the group consisting of fluorine resin
particles, boron nitride particles, molybdenum disulfide
particles, and silicon carbide particles are dispersed in a
metal matrix material.
As an example of the dispersive plating layer formation
method, there is proposed a general plating method
comprising: filling an electroplating bath or an electroless
plating bath with a dispersive-particle-containing plating
solution obtained by dispersing at least one kind of
particles selected from the group consisting of fluorine
resin particles, boron nitride particles, molybdenum
disulfide particles, and silicon carbide particles in a
plating solution containing a metal matrix material;
immersing a wire mesh into the plating bath; and co-
depositing the dispersive particles and the metal onto the
surface of the wire mesh by a well-known electrolytic plating
technique or electroless plating technique. Heat-treating the
thus formed plating layer at a temperature of about 200 to
400 ° C or preferably of about 250 to 350 ° C provides the
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plating layer with a high hardness and superior durability.
Examples of the metal matrix material are nickel (Ni)
or nickel-based alloys such as nickel-phosphorous (Ni-P); and
iron (Fe) or iron-based alloys.
Examples of the fluorine resin particles are
polytetrafluoroethylene (PTFE), tetrafluoroethylene-
hexafluoropropylene copolymer, tetrafuloroethylene-
perfluoroalkylvinylether copolymer.
An Ni plating layer or Ni-P plating layer in which at
least one kind of particles selected from the group
consisting of fluorine resin particles, boron nitride
particles, and molybdenum disulfide particles are dispersed
has superior lubricity. In view of this, the aforementioned
plating layer is particularly preferred because of its high
friction noise suppressing effect. An Ni plating layer or Ni-
P plating layer in which silicon carbide particles are
dispersed has superior abrasion resistance, and accordingly,
is advantageous in suppressing generation of metallic powders.
The latter plating layer is preferred because of its effect
of suppressing friction noise resulting from abrasion of
metallic powders.
The dispersive particles with an average particle
diameter of 0.1 to 10 µm, specifically, 0.2 to 3 µm are
preferred because of their superior lubricity or abrasion
resistance.
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The content ratio of the dispersive particles relative
to the dispersive plating layer is preferably from 1 to 30 %
by mass, more preferably 5 to 15 % by mass, and furthermore
preferably 6 to 10 % by mass in terms of lubricity or
abrasion resistance. An unduly low content of the dispersive
particles may result in insufficient improvement in lubricity
or abrasion resistance, which may fail to sufficiently
suppress generation of friction noise.
The thickness of the dispersive plating layer is from 3
to 15 µm, preferably, from 5 to 10 µm. As far as the
dispersive plating layer satisfies the aforementioned
thickness range, a high effect of suppressing friction noise
is obtained. An unduly small thickness or an unduly large
thickness out of the thickness range may lower retainability
of the friction noise suppressing effect.
The annular seal member in the embodiment is produced
by the following process, using the aforementioned materials.
First, as shown in FIG. 4, a laminated member is formed
by superposing the zone wire mesh 15 formed with the
dispersive plating layer, and a band-shaped heat-resistant
seal sheet 16 one on top of the other. Then, a convolute
member 14 is formed by winding the laminated member as shown
in FIG. 5.
The widths and the lengths of the dispersive-plated
zone wire mesh 15 and the band-shaped heat-resistant seal
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sheet 16 are structurally calculated based on a mass ratio of
the wire mesh and the heat-resistant seal member necessary
for retaining the configuration and sealablity of the annular
seal member.
As shown in FIG. 5, preferably, the convolute member 14
is configured in such a manner that the length of the heat-
resistant seal sheet 16 is larger than the length of the
dispersive-plated zone wire mesh 15 so that the inner
peripheral surface and the outer peripheral surface of the
dispersive-plated zone wire mesh 15 are covered with the
heat-resistant seal sheet 16.
The convolute member 14 is mounted in a bottomed
annular die 20 provided with a solid cylindrical core 21 in
the middle part of the bottomed annular die 20, as shown in
FIG. 6B.
The bottomed annular die 20 includes, in its cavity, a
cylindrical wall surface 18 and a partially concave spherical
wall surface 19 continuing from the cylindrical wall surface
18. The solid cylindrical core 21 is provided in the middle
part of the bottomed annular die 20 to define the cylindrical
inner surface of the annular seal member.
First, the convolute member 14 is mounted on the solid
cylindrical core 21 of the bottomed annular die 20. In
mounting, the solid cylindrical core 21 is placed in a
central hollow portion of the convolute member 14.
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Next, the convolute member 14 mounted in the bottomed
annular die 20 is subjected to compression molding. The
compression molding is performed by compressing the convolute
member 14 by a punching device P located above the cavity 22.
In the case where expansive graphite is used as the heat-
resistant seal material, a compression pressure is preferably
set to such an extent that a bulk density of the expansive
graphite is about 1 to 2. By performing the compression
molding, the wire mesh can be exposed to such a degree as to
retain sealability on the sliding surface of the annular seal
member.
The degree of retaining sealability means a degree of
maintaining the function as the annular seal member in
practical use. Specifically, it is preferable to provide such
a sealability that an air leakage amount per minute from a
seal portion is equal to or less than 1L/min, preferably,
equal to or less than 0.5L/min in the case where, for
instance, the annular seal member is attached to an exhaust
pipe joint, an end of the exhaust pipe is closed, and an
internal pressure of the exhaust pipe is increased by drawing
the air into the interior of the exhaust pipe through the
other end thereof at 30 kPa (0.3kgf/cm2).
Performing the aforementioned compression molding
enables to produce the annular seal member 10 having the
features that the heat-resistant seal sheet 16 and the
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dispersive-plated zone wire mesh 15 are compressed together,
and the compressed wire mesh and the compressed heat-
resistant seal member are integrally formed. With this
arrangement, the wire mesh is exposed from the partially
convex spherical surface 2 serving as the sliding surface.
In this way, the annular seal member 10 having the
configuration as shown in FIG. 1 is produced.
Preferably, a lubricating layer formed by coating a
lubricating substance onto the sliding surface may be
additionally formed on the sliding surface of the annular
seal member produced by the aforementioned process in order
to enhance the lubricity of the sliding surface. The
formation of the lubricating layer is advantageous in
improving the lubricity at an initial period of oscillations
of the spherical exhaust pipe joint.
The lubricating layer can be formed by applying at
least one kind selected from the group consisting of fluorine
resins such as PTFE, boron nitrides, and molybdenum
disulfides onto the sliding surface. These compounds may be
used alone or in combination of two or more kinds thereof.
The lubricating layer can be formed by applying an
aqueous dispersion for forming the lubricating layer or a
like composition onto the sliding surface of the annular seal
member by means such as brushing, spraying, or dipping. The
thickness of the lubricating layer to be formed is a
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thickness capable of retaining lubricity in use for a
predetermined period. Specifically, a preferred thickness of
the lubricating layer is from about 30 to 200 µm.
The annular seal member 10 having the above features is
fittingly mounted on the pipe end portion 101 of the
spherical joint 100 for the exhaust pipe as shown in FIG. 15,
and is used as an exhaust gas seal member.
On the partially convex spherical surface 2 of the
annular seal member 10, there is exposed the wire mesh formed
with the dispersive plating layer, in which at least one kind
of particles selected from the group consisting of fluorine
resin particles, boron nitride particles, molybdenum
disulfide particles, and silicon carbide particles are
dispersed. Use of the annular seal member 10 as a seal member
for a spherical exhaust pipe joint enables to reduce a
friction resistance of the partially convex spherical surface
2 serving as the sliding surface of the annular seal member
10 against the surface of the seal seat 130 of the spherical
exhaust pipe joint, and to reduce abrasion of metal materials.
(Second Embodiment)
An exemplified production method of the annular seal
member is described in the first embodiment. The annular seal
member production method of the invention is not limited to
the foregoing production method.
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In the aforementioned production method, the annular
seal member is produced by winding the heat-resistant seal
sheet along with the dispersive-plated zone wire mesh formed
with the dispersive plating layer over the entirety of the
wire mesh surface to form the convolute member, and by
compression molding the convolute member.
Applying dispersive plating to a wire mesh including a
portion thereof where the wire mesh is not exposed from the
sliding surface of the seal member is, however, economically
disadvantageous. In view of this, there is proposed an
economically advantageous production method. Specifically,
the annular seal member production method in the second
embodiment comprises: forming a preform of an annular seal
member (also called as an annular seal member preform in the
specification) by compression molding a zone wire mesh (also
called as a non-dispersive-plated zone wire mesh in the
specification) to which a dispersive plating is not
performed; placing a wire mesh formed with a dispersive
plating layer (also called as a dispersive-plated wire mesh
in the specification), over the annular seal member preform
so that the outer peripheral surface of the annular seal
member preform is substantially covered; and compression
molding the dispersive-plated wire mesh and the annular seal
member preform together. The production method enables to
produce a wire mesh having a feature that the wire mesh
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formed with the dispersive plating layer is exposed
exclusively from at least one surface selected from the group
consisting of the outer peripheral surface and the inner
peripheral surface of the annular seal member, serving as
sliding surface.
The aforementioned production method is described in
detail referring to FIGS. 7A through 7C.
First, an annular seal member preform 30 as shown in
FIG. 7A is formed by compression molding in a similar manner
as in the first embodiment except that a non-dispersive-
plated zone wire mesh is used.
A dispersive-plated wire mesh 34 formed with a
dispersive plating layer is produced, as shown in FIG. 7B.
Then, the annular seal member preform 30 is covered with the
dispersive-plated wire mesh 34, as shown in FIG. 7C.
The configuration of the dispersive-plated wire mesh 34
is not specifically limited. Normally, the dispersive-plated
wire mesh 34 may have such dimensions and configuration as to
cover the outer peripheral surface of the annular seal member
preform 30.
Then, the annular seal member preform 30 covered with
the dispersive-plated wire mesh 34 is mounted in the bottomed
annular die 20 as shown in FIG. 6 for compression molding,
whereby an annular seal member is produced, with a compressed
wire mesh with the dispersive plating layer exposed
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exclusively from the outer peripheral surface of the annular
seal member, as the sliding surface.
(Third Embodiment)
The annular seal members 10 described in the first
embodiment and the second embodiment have the feature that
the partially convex spherical surface 2 corresponding to the
outer peripheral surface of the annular seal member 10 serves
as a sliding surface.
Alternatively, an annular seal member of the invention
may have such a configuration that an inner peripheral
surface thereof serve as a sliding surface. An example of the
annular seal member is described in the following.
An annular seal member 60 shown in FIG. 8 is an annular
seal member for use in a spherical exhaust pipe joint,
wherein the annular seal member has an inner peripheral
surface serving as a sliding surface.
The annular seal member 60 includes, in addition to a
truncated conical surface 62, an inner peripheral surface 61
having a cylindrical inner surface 63 continuing from the
truncated conical surface 62; an outer peripheral surface 66
having a truncated conical outer surface 64 corresponding to
the truncated conical surface 62, and a cylindrical outer
surface 65 continuing from the truncated conical outer
surface 64; and annular end surfaces 67 and 68 formed on a
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large-diameter side and a small-diameter side of the
truncated conical surface 62, respectively.
In use, the annular seal member 60 having the above
configuration is incorporated in a spherical joint 71 for an
exhaust pipe, as shown in FIG. 9, for instance.
Referring to FIG. 9, 72 and 82 each denotes an exhaust
pipe. A flange portion 73 is fixed to an outer peripheral
surface of the exhaust pipe 72 by welding or a like technique.
The annular seal member 60 is fittingly mounted on the
exhaust pipe 72, with the outer peripheral surfaces 64 and 65,
and the annular end surface 68 of the annular seal member 60
in fitting contact with an inner peripheral surface 78 of the
flange portion 73.
A flange portion 70 having a partially convex spherical
portion 69 is fixed to the exhaust pipe 82 opposingly
connected to the exhaust pipe 72 by welding or a like
technique. The exhaust pipe 82 is arranged in such a manner
that the partially convex spherical portion 69 is slidably
contacted with the truncated conical inner surface 62 of the
annular seal member 60.
With the annular seal member 60 having the above
configuration, oscillations of an automobile may cause
friction noise at a contact surface where the partially
convex spherical portion 69 of the flange portion 70 is
contacted with the truncated conical inner surface 62 of the
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annular seal member 60.
In view of the above, in use of the annular seal member
60 having the aforementioned configuration, a dispersive
plating layer is formed at least on the surface of the wire
mesh that is exposed from the truncated conical inner surface
62. This can suppress friction noise generated at the contact
surface where the partially convex spherical portion 69 of
the flange portion 70 is contacted with the truncated conical
inner surface 62 of the annular seal member 60.
The annular seal member for use in a spherical exhaust
pipe joint described in the first through the third
embodiments have the features that fluorine resin particles,
boron nitride particles, molybdenum disulfide particles, and
silicon carbide particles capable of providing enhanced
lubricity and abrasion resistance are adhered onto the wire
mesh that is exposed from the sliding surface of the annular
seal member with high adhesion. In this way, the adhesion of
the particles onto the wire mesh surface by dispersive
plating enables to provide enhanced adhesion, as compared
with an arrangement that a lubricating substance is adhered
onto the sliding surface, using a binder including a resin
component or a like component. Use of the annular seal member
described in the embodiment in a spherical exhaust pipe joint
enables to suppress friction noise that may be generated by
friction of the annular seal member against the seal seat,
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particularly, friction noise that may be generated at high
temperature ambient. The annular seal member for use in a
spherical exhaust pipe joint is preferably used as an annular
seal member for sealing a spherical joint for an exhaust pipe
to be used in drawing an exhaust air outside from an engine
of an automobile, a two-wheeled motor vehicle, or a like
vehicle, particularly, for sealing a spherical joint at a pipe
portion relatively close to the engine as a high temperature
section.
In the following, the inventive annular seal member for
use in a spherical exhaust pipe joint, and the production
method thereof will be described in detail referring to
examples. It should be appreciated that the invention is not
limited to the examples.
EXAMPLES
(Example 1)
[Production of Zone Wire Mesh]
As shown in FIG. 3, a cylindrical wire mesh 7 with a
mesh area of 4 mm square obtained by weaving or knitting two
fine metal wires each made of SUS 304 stainless steel and with
a diameter of 0.28 mm was passed between the pair of rollers 8
and 9, followed by pressing and winding.
Then, the wire mesh was cut into a zone wire mesh 15 of
35 mm in width (W) and 360 mm in length (L).
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[Production of Dispersive-plated Wire Mesh]
In a similar manner as the production process of the
zone wire mesh, a cylindrical wire mesh with a mesh area of 3
mm square obtained by weaving or knitting a fine metal wire
made of SUS304 stainless steel and with a diameter of 0.28 mm
was passed between the pair of rollers 8 and 9, followed by
pressing and winding. Thus, a zone wire mesh with 82 mm in
width for covering was produced.
A dispersive plating layer was formed on the
aforementioned zone wire mesh for covering by the following
process.
Specifically, prepared was a dispersive plating solution
containing a metal matrix material including an Ni-P alloy, and
PTFE particles with a content of 6 % by mass relative to the
total content of the Ni-P alloy and the PTFE particles. The
zone wire mesh was immersed in the plating solution for an
electroless plating. Thus, a dispersive plating layer was
formed on the wire mesh surface. After the formation of the
dispersive plating layer, the zone wire mesh was heat-treated
for one hour. Thus, a dispersive-plated zone wire mesh for
covering was produced.
An average particle diameter of the PTFE particles
contained in the dispersive plating layer was 0.3 \m, and a
thickness of the dispersive plating layer was 7 \m.
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Next, the dispersive-plated zone wire mesh for covering
was cut into a dispersive-plated wire mesh 34 with 82 mm in
width (W) and 35 mm in length (L).
[Production of Spherical Zone Annular Seal Member Preform]
As shown in FIG. 4, a zone wire mesh 15 with 35 mm in
width and 360 mm in length was superposed over an expansive
graphite sheet (PF-G3, product of Toyo Carbon Co., Ltd.) with
55 mm in width, 540 mm in length, and 0.4 mm in thickness, as a
heat-resistant seal sheet 16 to form a laminated member. Then,
the laminated member as shown in FIG. 5 was wound into a
convolute shape so that the heat-resistant seal sheet 16 was
exposed out of the zone wire mesh 15 by one turn. Thus, a
convolute member 14 was produced, with the heat-resistant seal
sheet 16 exposed from the inner peripheral surface and the
outer peripheral surface of the zone wire mesh 15.
Next, prepared was, as shown in FIG. 6B, a bottomed
annular die 20 with a cylindrical wall surface 18 and a
partially concave spherical wall surface 19 continuing from the
cylindrical wall surface 18 on the inner surface thereof. The
convolute member 14 was coaxially placed on a solid cylindrical
core 21, which was provided in the middle part of the bottomed
annular die 20 to form a cylindrical inner surface of an
annular seal member. Then, the convolute member 14 was
compressed in the die with a pressure of 20 MPa. By performing
the above process, produced was an annular seal member preform
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30, as shown in FIG. 7A, having a configuration defined by: a
cylindrical inner surface 31 for defining a through-hole to be
formed in the middle part of the annular seal member; a
partially convex spherical surface 32; an annular end surface
33 formed on a large-diameter side of the partially convex
spherical surface 32; and an annular end surface formed on a
small-diameter side of the partially convex spherical surface
32.
The annular seal member preform 30 produced by the above
process had 49.5 mm in the diameter of the cylindrical inner
surface 31, 63 mm in the large diameter of the partially convex
spherical surface 32, 53.5 mm in the small diameter of the
partially convex spherical surface 32, and 30 mm in the height
of the annular seal member preform 30.
Next, as shown in FIG. 7B, the dispersive-plated wire
mesh 34 was opened into a cylindrical shape, and the opened
dispersive-plated wire mesh 34 was covered onto the partially
convex spherical surface 32 of the annular seal member preform
30, as shown in FIG. 7C.
Then, the annular seal member preform 30 covered with
the dispersive-plated wire mesh 34 was subjected to compression
molding at a pressure of 300 MPa, using a die identical to the
die in the above process. Thereby, produced was a spherical
zone annular seal member 10 having such a configuration as
shown in FIG. 1, wherein the dispersive-plated wire mesh was
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exposed from the outer peripheral surface of the partially
convex spherical surface.
The spherical zone annular seal member 10 had 16.5 mm in
the height thereof, 49 mm in the diameter of the cylindrical
inner surface, 63.5 mm in the large diameter of the partially
convex spherical surface, and 53.5 mm in the small diameter of
the partially convex spherical surface.
[Assessment Method of Annular Seal Member]
The spherical zone annular seal member was mounted on a
spherical exhaust pipe joint unit 90 comprising two exhaust
pipes 92, 93 each with a diameter of 48 mm, and a spherical
joint for connecting the exhaust pipes 92, 93, as shown in FIG.
10. The exhaust pipes 92 and 93 were fixed to each other in
such a manner that a relative angular displacement was allowed
by bolts 95a and 95b via coil springs 94a and 95b, respectively.
The exhaust pipes were urged to each other by a spring force of
about 590N.
A gas burner 96 was disposed below the spherical exhaust
pipe joint unit 90 to heat the spherical exhaust pipe joint
unit 90.
The spherical exhaust pipe joint unit 90 was oscillated
by an oscillating device under an oscillation condition of an
oscillation angle of ±4° and an oscillation frequency of 12 Hz.
The oscillation was conducted under the following temperature
condition.
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Specifically, the spherical exhaust pipe joint unit 90
was placed in a temperature condition of about 25 ° C for 50
minutes, followed by heating to 500 °C, and placing in a
temperature condition of 500 °C for 5 hours and 10 minutes.
The cycle of 6 hours was repeated four times, and the level of
friction noise, the weight reduction rate, and the gas leakage
amount were assessed each time the cycle was over by the
following method.
(Assessment on Friction Noise)
Sound pressure levels of friction noise were measured at
the points of time (i) when 50 minutes have elapsed at 25 °C,
and (ii) when 5 hours and 10 minutes have elapsed at 500 °C.
The measurements were conducted, as shown in FIG. 11, by
disposing an integrating sound level meter 97 (product of ACO
Co., Ltd. TYPE6226) at a position 10 cm away from the spherical
exhaust pipe joint unit 90 set on the oscillating device, and
by reducing the frequency of the spherical exhaust pipe joint
unit 90 to 1.6 Hz to suppress noise other than the friction
noise.
The measurement data was outputted to a general purpose
personal computer 98, and frequency dependencies of the sound
pressure level were analyzed by a spectrum analyzer (software
product of SOUND TECHNOLOGY). Examples of the analysis results
on friction noise are shown in FIGS. 12 and 13.
Also, a sensory assessment using the hearing sense was
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conducted concerning friction noise according to the following
criteria.
S: friction noise is hardly audible.
A+: friction noise is slightly audible when a
tester's ear is in close contact with the spherical exhaust
pipe joint unit.
A: friction noise is not audible within 1 m away
from the spherical exhaust pipe joint unit.
A-: friction noise is not audible within 2.5 m away
from the spherical exhaust pipe joint unit.
F: friction noise is audible 2.5 m away from the
spherical exhaust pipe joint unit.
(Weight Reduction Rate)
Each time the cycle was over, the annular seal member
was detached from the spherical exhaust pipe joint unit, and
the weight of the annular seal member was measured. A weight
reduction rate concerning the weight of the annular seal member
after the cycle test relative to the weight of the annular seal
member before the cycle test was measured.
(Gas Leakage Amount)
Each time the cycle was over, an end of the spherical
exhaust pipe joint unit was closed, and the air of 30 kPa
(0.3kgf/cm2) was drawn into the spherical exhaust pipe joint
unit through the other end thereof. The leakage amount of the
air from the annular exhaust pipe joint unit per minute was
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measured.
(Example 2)
An annular seal member was produced in the similar
manner as in Example 1 except that in a process of forming a
dispersive plating layer, used was a dispersive-plated wire
mesh formed by using silicon carbide (SiC) particles of an
average particle diameter of 1 µm according to an electroless
plating technique, in place of using the PTFE particles as in
Example 1.
The annular seal member was assessed according to the
same assessment method as in Example 1.
(Example 3)
An aqueous dispersion containing PTFE (polyfuron
dispersion D-1E (trade name) containing PTFE, product of Daikin
Industries, Ltd.) was applied onto the partially convex
spherical surface of the annular seal member preform obtained
in Example by brushing. Then, an aqueous dispersion containing
boron nitride (Sho BN UHP-1, product of Showa Denko Kabushiki
Kaisha) was sprayed, followed by drying. Thus, a lubricating
layer was formed.
Next, in the similar manner as in Example 1, a
dispersive-plated wire mesh 34 was covered onto an annular seal
member preform, followed by compression molding. Thus, a
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spherical zone annular seal member was produced. The spherical
zone annular seal member was assessed by the same assessment
method as in Example 1.
(Example 4)
A lubricating layer was formed on the partially convex
spherical surface of the spherical zone annular seal member
preform obtained in Example 2 in the similar manner as in
Example 3. Thus, a spherical zone seal member was produced in
the similar manner as in Example 3, and assessed by the same
assessment method as in Example 1.
(Examples 5 through 14)
Spherical zone annular seal members were produced in the
similar manner as in Example 3 except that the thickness of the
plating layer, and the content ratio of PTFE particles were
adjusted as recited in Table 4. A sensory assessment using the
hearing sense was conducted concerning friction noise.
(Comparative Example 1)
A spherical zone annular seal member was produced and
assessed in the similar manner as in Example 1 except that a
non-dispersive-plated wire mesh was used, in place of using the
dispersive-plated wire mesh 31 in Example 1.
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(Comparative Example 2)
A spherical zone seal member was produced by forming a
lubricating layer on the partially convex spherical surface of
the spherical zone annular seal member produced in Comparative
Example 1 in the similar manner as in Example 3. The spherical
zone seal member was assessed by the same assessment method as
in Example 1.
The assessment results on the examples and the
comparative examples are shown in Tables 1 through 4.
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Table 2

Table 3
j
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FIGS. 12 and 13 also show examples of analysis results
on frequency dependencies of sound pressure level measured by
a sound level meter. FIG. 12 is a graph showing frequency
dependencies of sound pressure level at 500 °C at the fourth
cycle in Example 3 and Comparative Example 2. FIG. 13 is a
graph showing frequency dependencies of sound pressure level
at 25 °C at the fourth cycle in Example 2 and Comparative
Example 1.
As shown in FIG. 12, there was observed a peak of sound
pressure level around 2 kHz at high temperature ambient of
500 °C.
As shown in Table 1, the friction sounds at the fourth
cycle at 500 ° C in Examples 1 through 4 had sound pressure
levels ranging from 66 to 73 dB at 2.0 kHz, and the sensory
assessments on the friction sounds were all labeled with "S",
which means that the friction sound is hardly audible. On the
other hand, in Comparative Examples 1 and 2, the friction
sounds were increased from the second cycle, and the sound
pressure levels at 2.0 kHz at the fourth cycle were as high
as 115 dB and 118 dB, respectively. The sensory assessment on
the friction sounds in Comparative Examples 1 and 2 at the
fourth cycle were both labeled with "F".
The results on weight reduction rate in Table 2 show
that the weight reduction rates at the fourth cycle in
Examples 1 through 4 were as low as from 1.29 to 1.35 %,
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whereas the weight reduction rates at the fourth cycle in
Comparative Examples 1 and 2 were as high as 1.84 % and
1.61 %, respectively. Thus, there was observed a considerable
difference in abrasion resistance between Examples 1 through
4, and Comparative Examples 1, 2.
The results on gas leakage amount in Table 3 show that
there was not observed a considerable difference between
Examples 1 through 4, and Comparative Examples 1, 2.
On the other hand, the sensory assessment results using
the hearing sense, concerning friction sounds from the
annular seal members in Examples 5 through 14, in which the
plating thickness and the content ratio of the dispersive
particles were varied, show that the friction sound
suppressing effect is particularly high in the plating
thickness from 5 to 15 µm.
As described above in detail, an aspect of the
invention is directed to an annular seal member for use in a
spherical exhaust pipe joint provided with, on an inner
peripheral surface or an outer peripheral surface thereof, a
sliding surface for slidably moving the spherical exhaust
pipe joint. The annular seal member comprises: an annular
mesh structural body including a compressed wire mesh; and a
heat-resistant sheet member which is compressed to be
integrally formed with the compressed wire mesh, wherein at
least a part of the compressed wire mesh which is exposed
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from the sliding surface has a dispersive plating layer in
which at least one kind of particles selected from the group
consisting of fluorine resin particles, boron nitride
particles, molybdenum disulfide particles, and silicon
carbide particles are dispersed.
The above arrangement is advantageous in suppressing
friction noise that may be generated by abrasion of the
sliding surface of the annular seal member against the
surface of a seal seat, particularly, friction noise that may
be generated by abrasion of metals at high temperature
ambient. Also, this arrangement enables to suppress abrasion
of the sliding surface, which allows for retaining
sealability of the annular seal member for an extended period.
Preferably, the annular seal member may have a
spherical zone configuration including a cylindrical inner
surface for defining a through-hole to be formed in the
middle part of the annular seal member^, and an outer
peripheral surface shaped into partially convex spherical
surface, and the outer peripheral surface shaped into the
partially convex spherical surface may be the sliding surface.
This arrangement is advantageous in reducing the friction
noise in a conventional spherical exhaust pipe joint of a
general configuration.
Preferably, the annular seal member for use in a
spherical exhaust pipe joint may be a spherical zone seal
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member having a configuration defined by: a cylindrical inner
surface; a partially convex spherical surface; an annular end
surface formed on a large-diameter side of the partially convex
spherical surface; and an annular end surface formed on a
small-diameter side of the partially convex spherical surface.
The spherical zone seal member may include a compressed wire
mesh, and a heat-resistant seal member which is compressed and
filled in the compressed wire mesh to be integrally formed with
the compressed wire mesh. The compresses wire mesh may be
exposed from the partially convex spherical surface to such a
degree as to retain sealability of the annular seal member.
The dispersive plating layer may be formed on at least the part
of the compressed wire mesh which is exposed from the partially
convex spherical surface.
Preferably, the dispersive plating layer may be an Ni
(nickel) plating layer, or an Ni-P (nickel-phosphorous)
plating layer, in which at least one kind of particles
selected from the group consisting of fluorine resin
particles, boron nitride particles, and molybdenum disulfide
particles are dispersed. This arrangement provides
particularly superior lubricity, and accordingly, is
advantageous in suppressing friction noise.
Preferably, the dispersive plating layer may be an Ni
plating layer, or an Ni-P plating layer, in which silicon
carbide particles are dispersed. This arrangement provides
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particularly superior abrasion resistance, and accordingly,
is advantageous in suppressing generation of metallic powders.
Therefore, the arrangement is advantageous in suppressing
friction noise resulting from abrasion of metallic powders.
Preferably, the dispersive plating layer may have a
thickness from 5 to 15 µm, which is advantageous in providing
superior durability while securing the friction noise
suppressing effect.
Preferably, the annular seal member may further
comprise a lubricating layer, on the sliding surface,
containing at least one kind selected from the group
consisting of fluorine resins, boron nitrides, and molybdenum
disulfides. This is advantageous in reducing friction noise
at an initial stage of oscillation.
Preferably, the compressed wire mesh may include a
dispersive-plated compressed wire mesh having at least a part
thereof being exposed from the sliding surface, and a non-
dispersive -plated compressed wire mesh which is not exposed
from the sliding surface. This is advantageous in providing a
less costly annular seal member for use in a spherical
exhaust pipe joint.
Another aspect of the invention is directed to a method
for producing an annular seal member for use in a spherical
exhaust pipe joint. The method comprises: a convolute member
forming step of superposing, one on top of the other, a band-
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shaped heat-resistant seal sheet, and a dispersive-plated
zone wire mesh having a dispersive layer in which at least
one kind of particles selected from the group consisting of
fluorine resin particles, boron nitride particles, molybdenum
disulfide particles, and silicon carbide particles are
dispersed to form a laminated member, and of winding the
laminated member into a convolute member; a convolute member
mounting step of mounting the convolute member in a bottomed
annular die provided with a solid cylindrical core in the
middle part of the bottomed annular die; and a compression
molding step of compression molding the convolute member in a
direction of a center axis of the convolute member. The
production method is advantageous in easily producing the
inventive annular seal member for use in a spherical exhaust
pipe joint.
Yet another aspect of the invention is directed to a
method for producing an annular seal member for use in a
spherical exhaust pipe joint. The method comprises: a
convolute member forming step of superposing a non-
dispersive -plated zone wire mesh and a band-shaped heat-
resistant seal sheet one on top of the other to form a
laminated member, and of winding the laminated member into a
convolute member; a first compression molding step of
mounting the convolute member in a bottomed annular die
provided with a solid cylindrical core in the middle part of
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the bottomed annular die, and of compression molding the
convolute member in a direction of a center axis of the
convolute member to form an annular seal member perform; and
a second compression molding step of placing a dispersive-
plated wire mesh in which at least one kind of particles
selected from the group consisting of fluorine resin
particles, boron nitride particles, molybdenum disulfide
particles, and silicon carbide particles are dispersed over
the annular seal member perform in such a manner that at
least one surface selected from the group consisting of an
outer peripheral surface and an inner peripheral surface of
the annular seal member perform is covered by the dispersive-
plated wire mesh, and of compression molding the dispersive-
plated wire mesh and the annular seal member perform together.
The production method is advantageous in producing the
inventive annular seal member for use in a spherical exhaust
pipe joint with a less cost.
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CLAIMS
1. An annular seal member for use in a spherical
exhaust pipe joint provided with, on an inner peripheral
surface or an outer peripheral surface thereof, a sliding
surface for slidably moving the spherical exhaust pipe joint,
comprising:
an annular mesh structural body including a compressed
wire mesh; and
a heat-resistant sheet member which is compressed to be
integrally formed with the compressed wire mesh, wherein
at least a part of the compressed wire mesh which is
exposed from the sliding surface has a dispersive plating
layer in which at least one kind of particles selected from
the group consisting of fluorine resin particles, boron
nitride particles, molybdenum disulfide particles, and
silicon carbide particles are dispersed.
2. The annular seal member for use in a spherical
exhaust pipe joint according to claim 1, wherein
the annular seal member has a spherical zone
configuration including a cylindrical inner surface for
defining a through-hole to be formed in the middle part of
the annular seal member, and an outer peripheral surface
shaped into a partially convex spherical surface, and
the outer peripheral surface shaped into the partially
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convex spherical surface is the sliding surface.
3. The annular seal member for use in a spherical
exhaust pipe joint according to claim 1, wherein
the dispersive plating layer is an Ni (nickel) plating
layer, or an Ni-P (nickel-phosphorous) plating layer, in
which at least one kind of particles selected from the group
consisting of fluorine resin particles, boron nitride
particles, and molybdenum disulfide particles are dispersed.
4. The annular seal member for use in a spherical
exhaust pipe joint according to claim 1, wherein
the dispersive plating layer is an Ni plating layer, or
an Ni-P plating layer, in which silicon carbide particles are
dispersed.
5. The annular seal member for use in a spherical
exhaust pipe joint according to claim 1, wherein
the dispersive plating layer has a thickness from 5 to
15 µm.
6. The annular seal member for use in a spherical
exhaust pipe joint according to claim 1, further comprising:
a lubricating layer, on the sliding surface, containing
at least one kind selected from the group consisting of
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fluorine resins, boron nitrides, and molybdenum disulfides.
7. The annular seal member for use in a spherical
exhaust pipe joint according to claim 1, wherein
the compressed wire mesh includes a dispersive-plated
compressed wire mesh having at least a part thereof being
exposed from the sliding surface, and a non-dispersive-plated
compressed wire mesh which is not exposed from the sliding
surface.
8. A method for producing an annular seal member
for use in a spherical exhaust pipe joint, comprising:
a convolute member forming step of superposing, one on
top of the other, a band-shaped heat-resistant seal sheet,
and a dispersive-plated zone wire mesh having a dispersive
plating layer in which at least one kind of particles
selected from the group consisting of fluorine resin
particles, boron nitride particles, molybdenum disulfide
particles, and silicon carbide particles are dispersed to
form a laminated member, and of winding the laminated member
into a convolute member;
a convolute member mounting step of mounting the
convolute member in a bottomed annular die provided with a
solid cylindrical core in the middle part of the bottomed
annular die; and
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a compression molding step of compression molding the
convolute member in a direction of a center axis of the
convolute member.
9. A method for producing an annular seal member
for use in a spherical exhaust pipe joint, comprising:
a convolute member forming step of superposing a non-
dispersive-plated zone wire mesh and a band-shaped heat-
resistant seal sheet one on top of the other to form a
laminated member, and of winding the laminated member into a
convolute member;
a first compression molding step of mounting the
convolute member in a bottomed annular die provided with a
solid cylindrical core in the middle part of the bottomed
annular die, and of compression molding the convolute member
in a direction of a center axis of the convolute member to
form an annular seal member perform; and
a second compression molding step of placing a
dispersive-plated wire mesh in which at least one kind of
particles selected from the group consisting of fluorine
resin particles, boron nitride particles, molybdenum
disulfide particles, and silicon carbide particles are
dispersed over the annular seal member perform in such a
manner that at least one surface selected from the group
consisting of an outer peripheral surface and an inner
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peripheral surface of the annular seal member perform is
covered by the dispersive-plated wire mesh, and of
compression molding the dispersive-plated wire mesh and the
annular seal member perform together.
- 51 -

An annular seal member for use in a spherical exhaust
pipe joint is provided with, on an inner peripheral surface
and an outer peripheral surface thereof, a sliding surface
for slidably moving the spherical exhaust pipe joint. The
annular seal member includes an annular mesh structural body
having a compressed wire mesh; and a heat-resistant sheet
member which is compressed to be integrally formed with the
compressed wire mesh. At least a part of the compressed wire
mesh which is exposed from the sliding surface has a
dispersive plating layer in which at least one kind of
particles selected from the group consisting of fluorine
resin particles, boron nitride particles, molybdenum
disulfide particles, and silicon carbide particles are
dispersed.