U.S. patent application number 09/180559 was filed with the patent office on 2002-01-03 for method of manufacturing composite insulator and packing member for use in same.
Invention is credited to GOTO, DAISAKU, KASHIWAGI, HIROSHI, TANI, TAKAO.
Application Number | 20020000326 09/180559 |
Document ID | / |
Family ID | 13023191 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020000326 |
Kind Code |
A1 |
GOTO, DAISAKU ; et
al. |
January 3, 2002 |
METHOD OF MANUFACTURING COMPOSITE INSULATOR AND PACKING MEMBER FOR
USE IN SAME
Abstract
In a method of producing a composite insulator having a core
member, end fitting members fixed to both end portions of the core
member, and an overcoat member including a sheath portion formed on
an outer surface of the core member and shed members, the overcoat
member and the end fitting member are connected by curing.
Moreover, a clamping operation is performed or a packing member is
used for preventing a flow of an overcoat forming material into a
seal portion. In this manner, it is possible to improve a seal
performance of a connection boundary between the end fitting member
and the overcoat member.
Inventors: |
GOTO, DAISAKU; (NAGOYA-SHI,
JP) ; KASHIWAGI, HIROSHI; (NAGOYA-SHI, JP) ;
TANI, TAKAO; (NAGOYA-SHI, JP) |
Correspondence
Address: |
STEPHEN P BURR
BURR & BROWN
P.O. BOX 7068
SYRACUSE
NY
13261-7068
US
|
Family ID: |
13023191 |
Appl. No.: |
09/180559 |
Filed: |
February 5, 1999 |
PCT Filed: |
March 10, 1998 |
PCT NO: |
PCT/JP98/00987 |
Current U.S.
Class: |
174/169 ;
174/179; 264/135; 264/263; 264/265; 264/278; 264/328.16 |
Current CPC
Class: |
H01B 19/00 20130101 |
Class at
Publication: |
174/169 ;
174/179; 264/135; 264/265; 264/278; 264/263; 264/328.16 |
International
Class: |
H01B 017/06; B29C
045/14 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 11, 1997 |
JP |
9-56,297 |
Claims
1. A method of producing a composite insulator having a core
member, end fitting members fixed to both end portions of the core
member, and an overcoat member including a sheath portion formed on
an outer surface of the core member and shed members, characterized
in that the overcoat member and the end fitting member are
connected by curing.
2. The method according to claim 1, wherein a surface of the end
fitting member is roughed when the curing is performed.
3. The method according to claim 1, wherein a surface of the end
fitting member is subjected to a phosphate treatment when the
curing is performed.
4. The method according to one of claims 1-3, wherein a primer is
applied to the end fitting member when the curing is performed.
5. The method according to one of claims 1-4, wherein the core
member and the end fitting member are set in the metal mold and the
overcoat member is heated for curing so that the core member and
the overcoat member are connected and the securing member and the
core member is also connected at the same time.
6. The method according to claim 5, wherein the core member to
which the end fitting members are clamped for connection is set in
the metal mold, the overcoat forming material is filled in the
overcoat forming space in the metal mold provided on the outer
portion of the core member, and the thus filled overcoat forming
material is cured under pressure to form the overcoat member.
7. The method according to claim 5, wherein the core member to
which the end fitting members are clamped for preliminarily
connection is set in the metal mold, the overcoat forming material
is filled in the overcoat forming space in the metal mold provided
on the outer portion of the core member, the thus filled overcoat
forming material is cured under pressure to form the overcoat
member, and the end fitting members are further clamed to both end
portions of the core member.
8. The method according to claim 5, wherein the core member to
which the end fitting members are arranged without clamping is set
in the metal mold, the overcoat forming material is filled in the
overcoat forming space in the metal mold provided on the outer
portion of the core member, the thus filled overcoat forming
material is cured under pressure to form the overcoat member, and
the end fitting members are clamed to both end portions of the core
member.
9. The method according to one of claims 5-8, wherein the overcoat
member is formed by a compression forming.
10. The method according to claim 9, wherein the end fitting member
is introduced into a predetermined position in the metal mold by
using a guide provided in the metal mold when the overcoat member
is formed by a compression forming.
11. The method according to claim one of claims 8-10, wherein the
overcoat forming material is filled into the overcoat forming space
in the metal mold provided on the outer portion of the core member
and is cured under such a state that a packing member for
preventing a flow of the overcoat forming material into a gap
between the core member and the end fitting members connected to
the end portions of the core member is provided.
12. The method according to claim 11, wherein the packing member is
formed by a material which does not affect a connection performance
with the overcoat forming material and a curing performance.
13. The method according to claim 11 or 12, wherein an inner shape
of the end fitting member permits a sliding of the packing
member.
14. The method according to one of claims 11-13, wherein, in the
case that the packing member is once set in the end fitting member,
if the end portion of the core member is moved in a direction
pulling up from the end fitting member, the packing member is not
mover in a direction pulling up from the position set in the end
fitting member.
15. The method according to one of claims 11-14, wherein the
packing member has a V-shaped cross section.
16. The method according to claim 15, wherein the packing member
has a V-shaped cross section which can be closely contacted to the
end surface of the end fitting member and the outer surface of the
core member near the end portion.
17. The method according to claim 1, wherein the overcoat member is
molded around the core member, the end fitting members are arranged
to both ends of the core member without clamping in such a manner
that the end portion of the end fitting member is overlapped on the
end portion of the overcoat member, an insulation polymer material
is arranged near a boundary exposed to an external atmosphere
between the end fitting member and the overcoat member and is cured
to seal the boundary between the end fitting member and the
overcoat member, and then the end fitting member is clamped to the
core member.
18. The method according to claim 1, wherein the overcoat member is
molded around the core member, the end fitting members are arranged
to both ends of the core member without clamping in such a manner
that a gap is existent between the end portion of the end fitting
member and the end portion of the overcoat member, an insulation
polymer material is arranged near a boundary exposed to an external
atmosphere between the end fitting member and the overcoat member
and is cured to seal the boundary between the end fitting member
and the overcoat member, and then the end fitting member is clamped
to the core member.
19. The method according to claim 17 or 18, wherein the insulation
polymer material is the same as that of the overcoat forming
material which forms the overcoat member.
20. The method according to one of claims 17-19, wherein the
insulation polymer material is formed by using another metal mold
as that used for forming the overcoat member.
21. A packing member used for the method of producing a composite
insulator having a core member, end fitting members fixed to both
end portions of the core member, and an overcoat member including a
sheath portion formed on an outer surface of the core member and
shed members, and arranged for preventing a flow of the overcoat
forming material into a gap between the core member and the end
fitting member fixed to an end portion of the core member,
characterized in that, if the packing member is once positioned in
the end fitting member, the packing member is not moved in a
direction pulling up from a position at which the packing member is
positioned, when the end portion of the core member is moved in a
direction pulling up from the end fitting member.
22. The packing member according to claim 21, wherein the packing
member has a V-shaped cross section.
23. The packing member according to claim 22, wherein the packing
member has a V-shaped cross section which is closely contacted to
the end surface of the end fitting member and the outer surface of
the core member near the end portion.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of producing a
composite insulator comprising a core member made of for example
FRP, end fitting members fixed to both end portions of the core
member, and an overcoat member made of insulation material having a
sheath portion formed on an outer surface of the core member and
shed portions, and also relates to a packing member used for this
composite insulator producing method which is arranged for
preventing a flow of an overcoat forming material into a gap
between the core member and the end fitting member fixed to both
end portions of the core member.
BACKGROUND ART
[0002] Up to the present, the composite insulator comprising the
core member, the end fitting members fixed to both end portions of
the core member, and the overcoat member having the sheath portion
formed on the core member and the shed portions is produced by
various methods for example by arranging the end fitting members on
both end portions of the core member, setting the core member and
the end fitting members in a metal mold, filling the overcoat
forming material in the metal mold, and curing the overcoat forming
material. Moreover, in order to improve a seal performance between
the end fitting member and the overcoat forming material, there is
known a technique such that an overcoat forming material of room
temperature hardening type (RTV) is used as the overcoat forming
material, and also there is known a technique such that a material
such as silicone gel is arranged between the end fitting member and
the overcoat forming material.
[0003] Even in the method using the RTV or the method using
silicone gel mentioned above, it is possible to maintain a normal
seal performance, but recently more excellent seal performance is
to be required. Therefore, particularly in the case of the
composite insulator in which the overcoat member is made of an
insulation material such as silicone rubber, there is a desire to
obtain a method of producing a composite insulator in which a seal
performance of a connection boundary between the end fitting member
and the overcoat forming material can be maintained and an end
portion of the core member can be firmly connected to an inner
surface of a core member insertion hole of the end fitting
member.
DISCLOSURE OF THE INVENTION
[0004] An object of the invention is to eliminate the drawbacks
mentioned above and to provide a method of producing a composite
insulator in which a seal performance of a connection boundary
between a end fitting member and an overcoat member can be improved
and a packing member used for this producing method.
[0005] According to the invention, a method of producing a
composite insulator having a core member, end fitting members fixed
to both end portions of the core member, and an overcoat member
including a sheath portion formed on an outer surface of the core
member and shed members, is characterized in that the overcoat
member and the end fitting member are connected by curing.
[0006] According to the invention, a packing member used for the
method of producing a composite insulator having a core member, end
fitting members fixed to both end portions of the core member, and
an overcoat member including a sheath portion formed on an outer
surface of the core member and shed members, and arranged for
preventing a flow of the overcoat forming material into a gap
between the core member and the end fitting member fixed to an end
portion of the core member, is characterized in that, if the
packing member is once positioned in the end fitting member, the
packing member is not moved in a direction pulling up from a
position at which the packing member is positioned, when the end
portion of the core member is moved in a direction pulling up from
the end fitting member.
[0007] In the method of producing a composite insulator according
to the invention, since a seal portion between the overcoat member
and the end fitting member is constructed by curing, it is possible
to improve a seal performance between the overcoat member and the
end fitting member. Moreover, in the preferred embodiment, it is
possible to provide a more firm curing connection between the end
fitting member and the overcoat member by roughing an upper surface
of the end fitting member or by subjecting a phosphate treatment to
a galvanization of a surface of the end fitting member.
[0008] In the preferred embodiment of the method of producing a
composite insulator according to the invention, the seal portion is
cured for connection under a condition such that the end fitting
member is not clamped to the end portion of the core member. In
addition, the core member itself or an end portion of the core
member and an inner surface of a core member insertion hole are
finely worked so as to prevent a substantial flow of the overcoat
forming material between an outer end surface of the core member
and an inner surface of the core member insertion hole of the end
fitting member when the end portion of the core member is inserted
into the core member insertion hole of the end fitting member, and
thus the end fitting member is fixed to the core member before
forming operation or the end fitting member is preliminarily fixed
to the core member before forming operation. If the overcoat
forming material is flowed between an end portion of the core
member and an inner surface of the core member insertion hole of
the end fitting member, it is not possible to clear an specified
tensile strength due to an abrasion resistance between the core
member and the end fitting member.
[0009] Moreover, in the preferred embodiment of the method of
producing a composite insulator according to the invention, since
the seal portion defined by the overcoat member, the core member
and the end fitting member is integrally formed by arranging the
end fitting members to the both end portions of the core member
without clamping, setting them in the metal mold, filling the
overcoat forming material into an overcoat forming space between an
outer surface of the core member and the metal mold, and curing
under pressure so as to form the overcoat member and to connect the
overcoat member to the end fitting member, or since the boundary
between the end fitting member and the overcoat member is sealed by
mold-forming the overcoat member around the core member, arranging
the end fitting members at both end portions of the core member
without clamping in such a manner that an end portion of the end
fitting member is overlapped on an end portion of the overcoat
member, arranging an insulation polymer material near the boundary
exposed externally between the end fitting member and the overcoat
member, and heating the insulation polymer material so as to cure
the insulation polymer material, or since the boundary between the
end fitting member and the overcoat member is sealed by
mold-forming the overcoat member around the core member, arranging
the end fitting members at both end portions of the core member
without clamping in such a manner that a gap is existent between an
end portion of the end fitting member and an end portion of the
overcoat member, arranging an insulation polymer material in the
gap between the end fitting member and the overcoat member, and
heating the insulation polymer material so as to cure the
insulation polymer material, it is possible to improve the seal
performance. In addition, since a clamping operation with respect
to an end portion of the core member is performed only once, it is
possible to reduce an amount of producing steps of the composite
insulator.
[0010] Further, in the method of producing a composite insulator
comprising a core member, end fitting member fixed to both end
portions of the core member, and an overcoat member having a sheath
portion formed on an outer surface of the core member and shed
portions, the packing member according to the invention is provided
for preventing a flow of an overcoat forming material into a gap
between the core member and the end fitting member fixed to an end
of the core portion. If the packing member is once positioned in
the end fitting member, this packing member is not moved in a
direction pulling up from a position at which the packing member is
positioned, when the end portion of the core member is moved in a
direction pulling up from the end fitting member.
[0011] Accordingly, in the case that the composite insulator is
transferred after the end fitting member is inserted into an end
portion of the core member and the packing member is positioned at
a predetermined portion in the end fitting member, if an end
portion of the core member is moved in a direction pulling up from
the end fitting member, the packing member is not moved in a
direction pulling up from the position at which the packing member
is preliminarily positioned in the end fitting member and is
maintained at a predetermined position in the end fitting
member.
[0012] Therefore, it is possible to stably seal a boundary between
the core member and the end fitting member and to prevent a flow of
overcoat forming material into a boundary between the core member
and an inner surface of the core member insertion hole of the end
fitting member. Moreover, since a metal mold is preliminarily
heated and shows a thermal expansion due to a shortening of forming
time and the core member maintained at room temperature is arranged
in the heated metal mold, the overcoat member is formed under such
a condition that an end surface of the core member is inserted into
the core member insertion hole of the end fitting member with a
little gap between an end surface of the core member and a bottom
surface of the core member insertion hole or that an end surface of
the core member is once connected to an bottom surface of the core
member insertion hole and then the core member is slightly pulled
up from the core member insertion hole so as to generate a little
gap between an end surface of the core member and a bottom surface
of the core member insertion hole. Even in the latter case, if the
end fitting member is inserted into an end portion of the core
member and the packing member is once positioned at a predetermined
position in the end fitting member, the packing member is not moved
in a direction pulling up from the position at which the packing
member is once positioned and is maintained at a predetermined
position in the end fitting member. Therefore, it is possible to
stably seal a boundary between the core member and the end fitting
member and to prevent a flow of overcoat forming material into a
boundary between the core member and an inner surface of the core
member insertion hole of the end fitting member.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a schematic view for explaining one embodiment of
a method of producing a composite insulator according to the
invention, wherein
[0014] FIG. 1(a) is a cross sectional view showing a state such
that the end fitting members are arranged to both end portions of
the core member and
[0015] FIG. 1(b) is a cross sectional view illustrating a state
such that the core member to which the end fitting members are
arranged is set between a pair of metal mold units and the core
member is fastened by the metal mold units;
[0016] FIG. 2(a) is a cross sectional view depicting a state such
that the end fitting members are arranged to both end portions of
the core member and
[0017] FIG. 2(b) is a cross sectional view showing a state such
that the core member to which the end fitting members are arranged
at the both end portions is set between a pair of metal mold units
and the core member is fastened by the metal mold units;
[0018] FIGS. 3(a)-(c) are schematic views for explaining a method
of producing a composite insulator according to the invention in
which an overcoat forming material is filled in a overcoat forming
space S between an outer portion of the core member and the metal
mold under the condition such that a packing member 6 is provided
for preventing a flow of overcoat forming material into a gap
between the core member and the end fitting member arranged to an
end portion of the core member, and the overcoat forming material
is cured under pressure;
[0019] FIG. 4 is a perspective view showing a packing member;
[0020] FIG. 5(a) is a perspective view illustrating another packing
member and
[0021] FIG. 5(b) is an enlarged cross sectional view of the another
packing member;
[0022] FIG. 6 is a cross sectional view depicting a state such that
the packing member shown in FIG. 5 is firmly connected to an end
surface of the end fitting member and an outer surface of the core
member near the end surface of the end fitting member;
[0023] FIG. 7 is a schematic view explaining one preferred
embodiment of a method of producing a composite insulator according
to the invention;
[0024] FIG. 8 is a schematic view showing another method of
producing a composite insulator according to the invention in an
order of producing steps;
[0025] FIG. 9 is a schematic view illustrating one end portion of
the composite insulator obtained according to the another method of
producing a composite insulator according to the invention;
[0026] FIG. 10 is a schematic view depicting still another method
of producing a composite insulator according to the invention in an
order of producing steps;
[0027] FIG. 11 is a schematic view showing a construction of one
end portion of the composite insulator obtained according to the
still another method of producing a composite insulator according
to the invention; and
[0028] FIG. 12 is a schematic view illustrating one embodiment of a
forming method of a seal portion in the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0029] FIG. 1 is a schematic view for explaining one embodiment of
a method of producing a composite insulator according to the
invention, wherein FIG. 1(a) is a cross sectional view showing a
state such that the end fitting members are arranged to both end
portions of the core member and FIG. 1(b) is a cross sectional view
illustrating a state such that the core member to which the end
fitting members are arranged is set between a pair of metal mold
units and the core member is fastened by the metal mold units.
Firstly, as shown in FIG. 1(a), end fitting members 12 are clamped
and fixed to both end portions of an FRP core 11 as a core member.
Then, as shown in FIG. 1(b), the FRP core 11 to which the end
fitting members 12 are clamped at both end portions is set in a
metal mold 13. Under such a condition, an overcoat forming material
such as silicone rubber is filled in an overcoat forming space s
defined on an outer surface of the FRP core 11 in the metal mold
13. After that, the thus filled overcoat forming material is cured
by applying heat and pressure thereto, thereby connecting the
overcoat forming material to the metal mold 13 and the end fitting
members 12. Moreover, as an another embodiment, the end fitting
members 12 are clamped for a preliminarily connection to the ends
of the FRP core 11 in the step shown in FIG. 1(a), and then a
composite insulator is once formed according to the same method
mentioned above. After that, the end fitting members 12 are clamped
again to the ends of the FRP core 11 to obtain a finally formed
composite insulator.
[0030] In the both embodiments mentioned above, the step of
connecting or preliminarily connecting the end fitting members 12
to the ends of the FRP core 11 is for preventing an insertion of
the overcoat forming material into a boundary between the end
fitting member 12 and the FRP core 11. Moreover, in the both
embodiments mentioned above, it is a feature of the invention that
the overcoat forming material is cured for connection to the end
fitting member 12. In the present invention, a phrase "the overcoat
forming material is cured for connection to the end fitting member
12" means that a seal portion between the overcoat member and the
end fitting member 12 is chemically reacted to obtain a firm
connection by the same reaction as the curing reaction in the
overcoat member forming step. It is preferred to perform the step
of curing the overcoat forming material to the end fitting member
12 at the same time as that the forming step such that the sheath
portion and the shed portions are cured under pressure.
[0031] In the embodiments mentioned above, it is preferred to rough
a surface of the end fitting member 12 to which the overcoat
forming material is contacted when the overcoat forming material is
cured for connection to the end fitting member 12. If the surface
of the end fitting member 12 is roughed, an oil component for
example adhered to the surface can be removed and a surface area
used for connection can be increased, so that it is possible to
perform a stable curing operation. A portion 95% or more of the
cured portion can be used for a connection in the case of the
roughed surface, but a portion only 20-80% of the cured portion can
be used for a connection in the case of the normal surface.
Moreover, if a phosphate treatment is performed with respect to a
surface of the end fitting member 12 to which the overcoat forming
material is contacted i.e. a surface on which a normal
galvanization is performed, a surface area is increased due to a
growth of an acicular crystalline of zinc phosphate, and the
surface is stabilized and is easy to be connected. Therefore, this
is a preferred embodiment.
[0032] In the present invention, as an overcoat forming method,
compression forming method, injection forming method, and transfer
forming method can be used. In this specification, an explanation
is made for the composite insulator having a solid core member, but
the present invention can be applied for a composite hollow
insulator having a cylindrical core member. Here, differences on
rubber material, forming condition etc. between the composite
insulator and the composite hollow insulator are shown in the
following Table 1. As shown in Table 1, rubber material and forming
condition such as forming pressure and forming temperature are
different between the composite insulator and the composite hollow
insulator due to whether the core member is solid or cylindrical.
Therefore, it is not always possible to apply the forming condition
of the composite hollow insulator to the composite insulator as it
is.
1TABLE 1 Differences on rubber material or forming condition
between hollow insulator and suspension insulator Item Hollow
insulator Suspension insulator Rubber state Liquid Solid Curing
reaction catalyst Platinum Organic peroxide Forming stress
10.about.20 kgf/cm.sup.2 80.about.200 kgf/cm.sup.2 Forming
temperature 20.about.80.degree. C. 150.about.200.degree. C.
[0033] In the embodiment mentioned above, when the step of curing
the end fitting member and the overcoat member is performed, the
end fitting member is connected or preliminarily connected to the
FRP core. The present inventors further investigated the embodiment
mentioned above, and found the following evidences. That is to say,
in the embodiment mentioned above, the overcoat member is formed by
arranging the overcoat forming material on an outer portion of the
core member after the end fitting member is clamped to the core
member for the purpose of preventing a flow of the overcoat forming
material. This is because it is not possible to clear a specified
tensile strength due to an abrasion resistance between the core
member and the end fitting member, if the overcoat forming material
is inserted between the end portion of the core member and the
inner surface of the core member insertion hole of the end fitting
member.
[0034] However, the present inventors further investigated in
detail the seal performance and the connection condition between
the end portion of the core member and the inner surface of the
core member insertion hole of the end fitting member, and found the
following results. That is to say, in the embodiment mentioned
above, a compression stress due to a clamping operation, within a
limit such that a crack is not generated in the core member, is
applied to the core member. However, since a heat over a glass
transition point is applied to the core member during the overcoat
member forming step, the core member is shrunk on its diameter and
thus there is a possibility such that a tensile strength of the
composite insulator is decreased.
[0035] Further investigation was conducted on the basis of the
results mentioned above and the following preferred embodiments
were found.
[0036] (1) The overcoat forming material is filled in the overcoat
forming space between the outer portion of the core member and the
metal mold under the condition such that the packing member for
preventing a flow of the overcoat forming material into a gap
between the core member and the end fitting member connected to the
end of the core member is provided, and is cured under pressure. In
this case, it is possible to stably seal a connection portion
between the core member and the end fitting member and to prevent a
flow of the overcoat forming material into a gap in the connection
portion between the core member and the inner surface of the core
member insertion hole. In addition, the inner end portion and the
outer end portion of the packing member is firmly contacted to an
end portion outer surface of the core member and the inner surface
of the core member insertion hole of the end fitting member
respectively.
[0037] (2) The packing member is made of a material which does not
prevent a connection performance with the overcoat forming material
or a material which does not affect the curing operation. In this
case, a desired connection by curing under pressure between the
overcoat member and the core member or between the end fitting
member and the overcoat member is not prevented even if the packing
member is provided. For example, this chan be accomplished by using
the same curing agent for those of the overcoat forming material
and the packing member.
[0038] (3) The inner portion of the end fitting member has a shape
such that the packing member can be set in the end fitting member
by sliding it. Therefore, even when the packing member is
positioned at near but correct position in the end fitting member,
the packing member can be slid and positioned in the end fitting
member by means of a filled overcoat forming material in the case
of filling the overcoat forming material in the overcoat forming
space between the metal mold and the outer portion of the core
member. Moreover, it is not necessary to position the packing
member in the inner portion of the end fitting mold strictly before
performing the overcoat member forming, and thus it is possible to
perform this step easily.
[0039] (4) In the case that the packing member is once positioned
in the end fitting member, the packing member is not moved in a
direction pulling up from the position at which it is positioned in
the end fitting member, even if the end portion of the core member
is moved in a direction pulling up from the end fitting member.
Even in the case that the overcoat member is formed under such a
condition that the end surface of the core member is once contacted
to the bottom surface of the insertion hole of the end fitting
member and then the core member is pulled up slightly from the end
fitting member to form a little gap between the end surface of the
core member and the bottom surface of the insertion hole of the end
fitting member, with taking into consideration of the case such
that the core member before expansion is arranged in a previously
heated and expanded metal mold, the packing member is stopped at a
predetermined position in the end fitting member without moving in
a direction pulling up from a position at which the packing member
is positioned with respect to the end fitting member. Therefore, it
is possible to stably seal the boundary between the core member and
the end fitting member and to prevent the flow of the overcoat
forming material into a gap between the core member and the inner
surface of the core member insertion hole of the end fitting
member.
[0040] (5) The packing member is a packing having a V-shape cross
section. In this case, both open end portions having a V-shape i.e.
an inner end portion and an outer end portion are firmly contacted
to an outer surface of the end portion of the core member and an
inner surface of the core member insertion hole of the end fitting
member respectively, and a valley portion positioned at an
intermediate portion of the both end portions having a V-shape is
positioned at a side of the bottom portion of the core member
insertion hole of the end fitting member as compared wit the both
open end portions. In this case, the position of the valley portion
is not limited to the just intermediate portion of the both open
end portions having a V-shape, and can be deviated toward either
sides of the open end portions i.e. an inner side or an outer side
in a diameter direction of the open end portions. Moreover, the
packing member may have a V-shape cross section to which the end
surface of the end fitting member and the surface of the core
member near the above end surface are closely contacted. In this
case, if the overcoat forming material is filled in the overcoat
forming space under such a condition that the packing member is set
at an outer surface of the core member, the packing member is
closely contacted to the end surface of the end fitting member and
the surface of the core member near the end surface mentioned above
without being bent by the overcoat forming material filling stress.
Therefore, it is possible to prevent the flow of the overcoat
forming material into the gap between the end fitting member and
the core member.
[0041] Hereinafter, preferred embodiments mentioned above will be
explained with reference to the drawings. FIG. 2(a) is a cross
sectional view showing a state such that the end fitting members
are arranged on the both end portions of the core member, and FIG.
2(b) is a cross sectional view illustrating a state such that the
core member to which the end fitting members are arranged at the
both end portions is set between a pair of metal mold units and the
core member is fastened by the metal mold units. In the figure, end
fitting members 2a, 2b are arranged respectively to both end
portions 1a, 1b of a core member 1 without clamping. Core member
insertion holes 3a, 3b are formed in the end fitting members 2a, 2b
respectively, and respective core member insertion holes 3a, 3b
have a two step hole construction comprising first small diameter
hole portions 3a-1, 3b-1 positioned at an outer side in an axial
direction and second large diameter hole portions 3a-2, 3b-2
positioned at an inner side in an axial direction. Diameters of the
first small diameter hole portions 3a-1, 3b-1 are worked in such a
manner that the column shaped core member is inserted with
substantially no gap into inner surfaces of the small diameter hole
portions. Diameters of the second large diameter hole portions
3a-2, 3b-2 positioned at the inner side in the axial direction are
larger than an outer diameter of the core member and thus a part of
the overcoat member is existent in a gap defined by an outer
surface of the core member and an inner surface of the large
diameter hole portion. In this manner, a seal length between the
end fitting member and the overcoat member is increased, and thus
it is possible to improve a seal performance. Cylindrical expanding
portions 4a, 4b positioned at an outer side in a radial direction
are arranged at cylindrical open end portions of the large diameter
hole portions 3a-2, 3b-2 of the end fitting members, and a seal
length between the end fitting member and the overcoat member is
further increased in the same manner as that of the large diameter
hole portion, so that a seal performance is further improved.
[0042] FIG. 2(b) is a cross sectional view illustrating a state
such that the core member 1 to which the end fitting members 2a, 2b
are arranged at the both end portions 1a, 1b is set between a pair
of metal mold units 5a, 5b and the core member is fastened by the
metal mold units. An overcoat forming space S is formed between a
pair of the metal mold units 5a, 5b. The overcoat forming space S
comprises a sheath forming portion S1 and shed forming portions S2.
Close contacts are accomplished between outer surfaces of open
cylindrical end portions of the large diameter hole portions 3a-2,
3b-2 of the end fitting members and the opposed metal mold units
and between the core member and inner surfaces of the core member
insertion holes of the end fitting members, and thus an outer side
and an inner side seals in a radial direction are achieved. The
cylindrical expanding portions 4a, 4b positioned at an outer side
in a radial direction are closely contacted to end portions of the
overcoat forming space S of the metal mold units. An overcoat
forming material is supplied in the overcoat forming space S from
an overcoat forming material feeding path not shown, and an
overcoat member is formed on an outer surface of the core member in
the overcoat forming space S by heating the overcoat forming
material under pressure, so that the overcoat member is connected
to the opposed surface of the end fitting member. If necessary, a
primer is preliminarily sprayed on surfaces of the end fitting
member and the core member to which the overcoat member is
contacted, and thus the overcoat member is connected to an outer
surface of the core member and the opposed surface of the end
fitting member via a primer. After that, a pair of the metal mold
units 5a, 5b are opened to pull up a formed composite insulator
body, and the end fitting members are clamped at the both end
portions of the core member under a predetermined clamping
stress.
[0043] FIGS. 3(a)-(c) are schematic views for explaining a method
of producing a composite insulator according to the invention in
which the overcoat forming material is filled in the overcoat
forming space S between an outer portion of the core member and the
metal mold under the condition such that a packing member 6 is
provided for preventing a flow of the overcoat forming material
into a gap between the core member 1 and the end fitting member 3a
(same as end fitting member 3b) arranged to an end portion of the
core member, and the overcoat forming material is cured under
pressure. In this embodiment, an inner shape of the large diameter
hole portion 3a-2 of the core member insertion hole 3a in the end
fitting member 2 permits a sliding of the packing member 6 so as to
set the packing member 6. In FIGS. 3(a)-(c), the packing member 6
has a V-shape cross section (refer to FIG. 4), and the both open
end portions i.e. an inner end portion 6-1 and an outer end portion
6-2 are firmly contacted to an outer surface of the end portion of
the core member 1 and an inner surface of the large diameter hole
portion 3a-2 of the end fitting member 2 respectively. In addition,
the valley portion 6-3 positioned at an intermediate portion of the
both open end portions having a V-shape is positioned at a bottom
side of the core member insertion hole (small diameter hole
portion) as compared with the both open end portions. In this case,
the valley portion is positioned at just intermediate portion of
the both open end portions having a V-shape.
[0044] FIG. 3(a) shows an intermediate step for positioning the
packing member at a predetermined position on the bottom portion of
the large diameter hole portion 3a-2 of the end fitting member 2a
shown in FIG. 3(b). The core member 1 shown in the state
illustrated in FIG. 3(b), in which the end fitting members 2a, 2b
are arranged to the both end portions 1a, 1b, is set between a pair
of the metal mold units 5a, 5b, and the metal mold units 5a, 5b are
closed. After that, the overcoat member is formed in the same
manner as explained in FIG. 2(b), and then the end fitting members
may be clamped to the core member if necessary. Otherwise, the core
member 1 maintained in the state shown in FIG. 3(a), in which the
end fitting members 2a, 2b are arranged to the both end portions
1a, 1b, is set between a pair of the metal mold units 5a, 5b, and
the metal mold units 5a, 5b are closed. After that, the overcoat
member is formed in the same manner as explained in FIG. 2(b), and
then the end fitting members are clamped to the core member. In
this case, the packing member is deformed externally in an axial
direction by the overcoat forming material supplied in the overcoat
forming space S, and is positioned as shown in FIG. 3(b).
[0045] FIG. 3(c) is a schematic view explaining the state such that
the packing member is not moved in a direction pulling up from the
position at which it is set in the end fitting member even if the
end portion of the core member is moved in a direction pulling up
from the end fitting member. That is to say, even in the case that
the overcoat member is formed under such a condition that the end
surface of the core member is once contacted to the bottom surface
of the insertion hole of the end fitting member and then the core
member is pulled up slightly from the end fitting member to form a
little gap between the end surface of the core member and the
bottom surface of the insertion hole of the end fitting member,
with taking into consideration of the case such that the core
member maintained at room temperature is arranged in a previously
heated and expanded metal mold, the packing member is stopped at a
predetermined position in the end fitting member without moving in
a direction pulling up from a position at which the packing member
is positioned with respect to the end fitting member. Therefore, it
is possible to stably seal the boundary between the core member and
the end fitting member and to prevent the flow of the overcoat
forming material into a gap between the core member and the inner
surface of the core member insertion hole of the end fitting
member.
[0046] FIG. 5(a) and FIG. 5(b) are a perspective view and an
enlarged cross sectional view respectively showing another
embodiment of the packing member shown in FIGS. 3(a)-(c). FIG. 6 is
a cross sectional view showing the state such that a packing member
6' is closely contacted to the inner side in a radial direction of
the core member insertion hole 3a i.e. the end surface of the large
diameter hole portion 3a-2 and the outer surface of the core member
near the end surface mentioned above. The packing member 6' has
little different construction and function as those of the packing
member 6, but has a substantially same function as that of the
packing member 6 shown in FIGS. 3(a)-(c). Therefore, the same
explanations conducted for the packing member 6 may be applied to
the packing member 6'. Hereinafter, different points will be
explained mainly.
[0047] The packing member 6' has the similar shape as that of the
packing member 6 and has a cross sectional shape shown in FIG.
5(b). More detail explanation is as follows. The packing member 6'
comprises a small diameter end portion 6'-1 which is contacted to
the outer surface of the core member under expanded state, a large
diameter end portion 6'-2 which is contacted to the inner side in
an axial direction of the core member insertion hole 3a provided in
the end fitting member under shrunk state i.e. the inner surface of
the second large diameter hole portion 3a-2, and a connection end
portion 6'-3 connected between the small diameter end portion 6'-1
and the large diameter end portion 6'-2 and positioned at the outer
side in an axial direction when the packing member is set between
the core member and the end fitting member. In addition, a
cylindrical depression portion 6'-4 serving as an easy bending in a
radial direction of the small diameter end portion 6'-1 and the
large diameter end portion 6'-2 is provided at the inner side in an
axial direction between the small diameter end portion 6'-1 and the
large diameter end portion 6'-2. In FIG. 5(a) and FIG. 5(b), no
load is applied to the packing member 6', and a broken line (1) and
a broken line (2) show respectively a fictitious inner surface of
the large diameter hole portion 3a-2 provided at the inner side in
an axial direction of the core member insertion hole 3a and a
fictitious outer surface of the core member. A first surface 6'-3a
of the connection end portion 6'-3 opposed to the core member is
extended substantially parallel to the outer surface of the core
member. Moreover, a second surface 6'-3b opposed to an inner end
surface of the second large diameter hole portion 3a-2 provided at
an inner side in an axial direction of the core member insertion
hole 3a of the end fitting member is extended substantially
parallel to the inner end surface of the second large diameter hole
portion 3a-2.
[0048] The overcoat forming material is filled in the overcoat
forming space after the packing member 6' is arranged to the outer
surface of the core member and is positioned in the second large
diameter hole portion 3a-2 provided at the inner side in an axial
direction of the core member insertion hole 3a of the end fitting
member and the metal mold units are closed. In this case, the
packing member 6' can be firmly fitted to the end surface of the
second large diameter hole portion 3a-2 provided at the inner side
in an axial direction of the core member and the outer surface of
the core member near the end surface mentioned above. Therefore, it
is possible to effectively prevent a flow of the overcoat forming
material into the gap between the outer surface of the core member
and the end fitting member. Moreover, when the packing member 6' is
pressed toward the metal member 3a by a forming stress and is
deformed, the first surface 6'-3a is firmly contacted to the core
member, and the second surface 6'-3b is fly contacted to the
connection surfaces of the metal member inner surfaces 3a-1, 3a-2.
Therefore, it is possible to prevent a flow of the overcoat forming
material into the gap between the outer surface of the core member
and the end fitting member.
[0049] Then, as a further preferred embodiment according to a
method of producing a composite insulator according to the
invention, an example such that the overcoat member is formed by a
compression forming and the end fitting member is introduced into a
predetermined position in the metal mold by using a guide provided
in the metal mold will be explained. FIG. 7 is a schematic view
explaining the preferred embodiment in the method of producing a
composite insulator according to the invention, wherein FIG. 7(a)
shows a side view and FIG. 7(b) illustrates a front view. In the
embodiment shown in FIGS. 7(a) and (b), an upper metal mold 31 and
a lower metal mold 32 are respectively constructed by integrating a
plurality of segments.
[0050] Both of the upper metal mold 31 and the lower metal mold 32
have a cavity 35 for setting end fitting members 42 provided at the
both end portions of an FRP core 41. Moreover, in the upper metal
mold 32, a guide is constructed in such a manner that a pair of
guide bars 36-1, 36-2 having a space with each other whose distance
is substantially same (little larger) as (than) a diameter of the
end fitting member 42 are arranged upwardly at end portions
corresponding to the end fitting members 42 respectively. Further,
cavities 37-1, 37-2, in which the guide bars 36-1, 36-2 are
settable when the upper metal mold 31 and the lower metal mold 32
are closed, are arranged at portions of the upper metal member 32
corresponding thereto.
[0051] A method of forming the overcoat member by a compression
forming by means of the upper metal mold 31 and the lower metal
mold 32 mentioned above is as follows. At first, a forming rubber
43 is wound and set on an outer surface of the FRP core 41 in which
the end fitting members 42 are inserted into its end portions
without clamping. Then, the FRP core 41, in which the forming
rubber 43 and the end fitting members 42 are set, is set at a
predetermined position on the lower metal mold 32 i.e. the end
fitting members 42 are set between the guide bars 36-1, 36-2 and
the end fitting members 42 are positioned at portions corresponding
to the cavity 35. After the settings mentioned above, if a stress
is applied under heating condition to the upper metal mold 31 and
the lower metal mold 32 so as to close them, a desired composite
insulator can be formed by a compression forming.
[0052] Then, another embodiment of a method of producing a
composite insulator according to the invention will be explained.
FIGS. 8(a)-(d) are schematic views showing successive steps of the
another embodiment of the method of producing the composite
insulator according to the invention in order. A construction of a
polymer insulator as one example of the composite insulator
according to the invention is the same as that of the known polymer
insulator. In this embodiment, as shown in FIG. 8(a), a layer 57
made of an overcoat forming insulation polymer material, here
silicone rubber, for forming an overcoat member 56 comprising a
sheath portion 53 and shed portions 54 is formed around an FRP core
52. Then, as shown in FIG. 8(b), the overcoat member 56 comprising
the sheath portion 53 and shed portions 54 is formed by performing
a mold operation using the metal mold not shown. Then, as shown in
FIG. 8(c), end fitting members 55-1, 55-2 are inserted into both
end portions of the FRP core 52. Respective steps explained up to
here are the same as those of the known one.
[0053] Features of the another embodiment according to the
invention mentioned above are as follows. As shown in FIG. 8(d),
when the end fitting members 55-1, 55-2 are arranged to both ends
of the FRP core 52, the end portions of the end fitting members
55-1, 55-2 are overlapped on the end portion of the overcoat member
56, and a silicone rubber member 62 made of preferably the same
material as that of the overcoat member 56 is arranged on a
boundary 61 exposed to the external atmosphere between the end
fitting members 55-1, 55-2 and the overcoat member 56 in such a
manner that the silicone rubber member 62 covers circumferentially
all of the boundary 56. Then, the thus obtained body is heated so
as to cure the silicone rubber member 62, so that the boundary 61
between the end fitting members 55-1, 55-2 and the overcoat member
56 is sealed. After that, the end fitting members 55-1, 55-2 are
clamped. In this manner, as shown in FIG. 9 as one end portion, it
is possible to obtain the polymer insulator 51 having a seal
portion 63 made of a cured connection portion showing an excellent
seal performance between the end fitting members 55-1, 55-2 and the
overcoat member 56. In the polymer insulator 51 according to the
invention produced in the manner shown in FIG. 8, since the cured
connection portion showing an excellent seal performance is
existent on the boundary 61 between the end fitting members 55-1,
55-2 and the overcoat member 56, a seal performance of the polymer
insulator 51 as a whole can be improved.
[0054] In the another embodiment according to the invention, when
the seal portion 63 is cured, the end fitting members 55-1, 55-2
are not clamped to the FRP core 52. Therefore, non-cured rubber
used for a curing connection may be intruded between the inner
surfaces of the end fitting members 55-1, 55-2 and the end portion
of the sheath portion 53. In order to prevent such a non-cured
rubber intrusion, prior to form the seal portion 63 by curing, it
is preferred to firmly contact the inner surfaces of the end
fitting members 55-1, 55-2 with respect to the end portion of the
sheath portion 53.
[0055] FIGS. 10(a)-(d) are schematic views showing successive steps
of still another embodiment of the method of producing the
composite insulator according to the invention in order. In this
embodiment, respective steps shown in FIGS. 10(a)-(c) are same as
those of the embodiments shown in FIGS. 8(a)-(c). In this
embodiment, different points from the embodiment shown in FIG. 8
are as follows. The end fitting members 55-1, 55-2 are arranged at
the both ends of the FRP core 52 in such a manner that a gap 71 is
existent between the end portions of the end fitting members 55-1,
55-2 and the end portion of the overcoat member 56, and a silicone
rubber member 72 made of preferably the same material as that of
the overcoat member 56 is arranged in the gap 71 between the end
portions of the end fitting members 55-1, 55-2 and the end portion
of the overcoat member 56. Then, the thus obtained body is heated
so as to cure the silicone rubber member 72, so that portions
between the end fitting members 55-1, 55-2 and the overcoat member
56 are sealed by the seal portion 73. In this manner, the polymer
insulator 51 whose one end portion is shown in FIG. 11 can be
obtained. Also in this embodiment, since the seal portion made of a
cured connection portion showing an excellent seal performance is
existent between the end portions of the end fitting members 55-1,
55-2 and the end portion of the overcoat member 56, a seal
performance of the polymer insulator 51 as a whole can be
improved.
[0056] In the still another embodiment according to the invention
mentioned above, when the seal portion made of the silicone rubber
member 72 is cured, the end fitting members 55-1, 55-2 are not
clamped to the FRP core 52. Therefore, non-cured silicone rubber
member 72 may be intruded between the inner surfaces of the end
fitting members 55-1, 55-2 and the end portion of the sheath
portion 53. In order to prevent such a non-cured rubber intrusion,
in the still another embodiment according to the invention
mentioned above, it is preferred that use is made of the packing
member 6 as shown in the previous embodiments mentioned above and
the packing member 6 is arranged on surfaces of the end portions of
the end fitting members 55-1, 55-2 which are contacted to the
silicone rubber member 72.
[0057] The polymer insulators 51 according to the another
embodiment and the still another embodiment mentioned above have an
advantage such that it is previously formed since only the overcoat
member 56 can be previously molded to the FRP core 52 in addition
to the above mentioned improvement of the seal performance.
Moreover, it can deal with an alternation of the shape of the end
fitting member preferably. Further, in the embodiment mentioned
above, an explanation is made to the example of the compression
forming such that the overcoat forming material is arranged on the
FRP core 52 and is molded by the metal mold, but the present
invention can be used for the other forming methods such as the
injection forming such that the overcoat forming material is
injected in the metal mold in which the FRP core 52 is set.
Furthermore, as a material of the seal portion which is cured
later, the present invention can be achieved even if the other
material as that of the overcoat member 6 is used.
[0058] FIG. 12 is a schematic view showing a state such that the
boundary 61 between the end fitting members 55-1, 55-2 and the
overcoat member 56 is sealed in the another embodiment according to
the invention. In this embodiment, a pair of an upper metal mold 82
and a lower metal mold 83 are set in such a manner that a cavity 81
is formed near the boundary 61 between the end fitting members
55-1, 55-2 and the overcoat member 56. Then, silicone rubber is
supplied into the cavity 81 through a supply inlet 84. After that,
the upper and lower metal molds are heated to form a seal portion
near the boundary 61 between the end fitting members 55-1, 55-2 and
the overcoat member 56. Also in the still another embodiment
according to the invention, it is possible to form the seal portion
in the substantially same manner as that of the another embodiment
mentioned above.
[0059] Industrial Applicability
[0060] As clearly understood from the above explanations, according
to the method of producing the composite insulator of the present
invention, since the seal portion between the overcoat member and
the end fitting member is cured for connection, it is possible to
improve the seal performance between the overcoat member and the
end fitting member. Moreover, according to the packing member of
the present invention, since a construction of the packing member
is specified, it is possible to firmly seal a portion between the
core member and the end fitting member and to prevent a flow of the
overcoat forming material into a portion between the core member
and the inner surface of the core member insertion hole of the end
fitting member.
* * * * *