U.S. patent application number 13/744017 was filed with the patent office on 2013-05-23 for fastener joint with sealing gasket.
This patent application is currently assigned to AIRBUS OPERATIONS LIMITED. The applicant listed for this patent is AIRBUS OPERATIONS LIMITED. Invention is credited to David Alistair SUTTON, Colin John WEST.
Application Number | 20130125374 13/744017 |
Document ID | / |
Family ID | 38829735 |
Filed Date | 2013-05-23 |
United States Patent
Application |
20130125374 |
Kind Code |
A1 |
WEST; Colin John ; et
al. |
May 23, 2013 |
FASTENER JOINT WITH SEALING GASKET
Abstract
A joint comprising: a first component having a face and a bore
defined by a bore wall; a second component; a fastener joining the
first component to the second component, the fastener comprising a
head and a shaft protruding from the head; and a polysulphide
gasket comprising a ring which is compressed between the head of
the fastener and the face of the first component; and a collar
between the shaft of the fastener and the bore wall. The gasket
comprises a ring of sealing material surrounding a hole for
receiving a fastener, the sealing material comprising an at least
partially cured polysulphide sealant. The gasket has a region of
increased thickness positioned towards the inner periphery of the
ring which flows to form the collar.
Inventors: |
WEST; Colin John; (Bristol,
GB) ; SUTTON; David Alistair; (Bristol, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AIRBUS OPERATIONS LIMITED; |
Bristol |
|
GB |
|
|
Assignee: |
AIRBUS OPERATIONS LIMITED
Bristol
GB
|
Family ID: |
38829735 |
Appl. No.: |
13/744017 |
Filed: |
January 17, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12680911 |
Mar 31, 2010 |
|
|
|
PCT/GB2008/050968 |
Oct 20, 2008 |
|
|
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13744017 |
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Current U.S.
Class: |
29/525.01 ;
411/371.1 |
Current CPC
Class: |
Y10T 29/49947 20150115;
F16J 15/14 20130101; Y10T 403/52 20150115; F16B 43/001 20130101;
F16B 19/008 20130101; F16B 33/004 20130101 |
Class at
Publication: |
29/525.01 ;
411/371.1 |
International
Class: |
F16B 19/00 20060101
F16B019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 23, 2007 |
GB |
0720705.3 |
Claims
1. A joint comprising: a first component having a face and a bore
defined by a bore wall; a second component; a fastener joining the
first component to the second component, the fastener comprising a
head and a shaft protruding from the head; and a polysulphide
gasket comprising a ring which is compressed between the head of
the fastener and the face of the first component; and a collar
between the shaft of the fastener and the bore wall
2. The joint of claim 1, wherein the gasket further comprises a
reinforcing element.
3. The joint of claim 2, wherein the reinforcing element comprises
a fabric.
4. The joint of claim 1, wherein the bore comprises a tapered
opening and the head of the fastener comprises a tapered head which
is received in the tapered opening.
5. The joint of claim 1, wherein the polysulphide material forming
the gasket is loaded with conductive particles.
6. A method of manufacturing a joint, the method comprising:
mounting a gasket on a fastener; the fastener comprising a head and
a shaft protruding from the head, and the gasket comprising an at
least partially cured polysulphide sealing material; inserting the
shaft of the fastener through a first component and at least
partially through a second component until the gasket engages the
first component; and compressing the gasket between the head of the
fastener and the first component whereby the sealing material flows
along the shaft of the fastener and forms a collar between the
shaft of the fastener and the first component.
7. The method of claim 6 wherein the gasket comprises a region of
increased thickness positioned towards the inner periphery of the
gasket which flows along the shaft of the fastener.
8. The method of claim 7 wherein the region of increased thickness
extends around the entire circumference of the gasket.
9. The method of claim 6 wherein the gasket further comprises a
reinforcing element.
10. The method of claim 9 wherein the gasket comprises a
matrix-rich region which contains a lower than average density of
reinforcement and which flows along the shaft of the fastener.
11. An aircraft comprising a joint according to any of claim 1.
Description
[0001] The present application is a divisional of U.S. application
Ser. No. 12/680,911, filed Mar. 31, 2010 and is national phase of
PCT/GB2008/050968, filed Oct. 20, 2008, and claims priority from,
British Application Number 0720705.3, filed Oct. 23, 2007, the
disclosures of which are hereby incorporated by reference herein in
their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a joint with a sealing
gasket, a gasket for use in such a joint, and a method of
manufacturing such a joint.
BACKGROUND OF THE INVENTION
[0003] EP 1548083 A1 describes a sealing material for use in
sealing joints. The sealing material comprises an at least
partially cured polysulphide sealant and a reinforcing element. The
sealing material is provided in the form of a sheet of uniform
thickness. The sheet is placed between the mating surfaces of the
components in the manner of a gasket, and the components are then
fastened together, for example with rivets or bolts.
[0004] While the sealing material will to some degree move away
from the fasteners as they are tightened, the curing of the sealant
material and the presence of the reinforcing element will, in
general, prevent the sealing material from moving entirely away
from the vicinity of the fasteners.
[0005] U.S. Pat. No. 3,022,870 describes a fastener joint with a
self-sustaining adherent polysulphide film forming a fluid-tight
seal between a pair of metal plates.
SUMMARY OF THE INVENTION
[0006] A first aspect of the invention provides a joint comprising:
a first component having a face and a bore defined by a bore wall;
a second component; a fastener joining the first component to the
second component, the fastener comprising a head and a shaft
protruding from the head; and a polysulphide gasket comprising a
ring which is compressed between the head of the fastener and the
face of the first component; and a collar between the shaft of the
fastener and the bore wall.
[0007] A second aspect of the invention provides a method of
manufacturing a joint, the method comprising: [0008] mounting a
gasket on a fastener; the fastener comprising a head and a shaft
protruding from the head, and the gasket comprising an at least
partially cured polysulphide sealing material; [0009] inserting the
shaft of the fastener through a first component and at least
partially through a second component until the gasket engages the
first component; and [0010] compressing the gasket between the head
of the fastener and the first component whereby the sealing
material flows along the shaft of the fastener and forms a collar
between the shaft of the fastener and the first component.
[0011] In contrast with the gaskets in EP 1548083 A1 and U.S. Pat.
No. 3,022,870, in which the sealant material forms a seal between
the mating pairs of components, the gasket of the present invention
forms a collar between the shaft of the fastener and the bore
wall.
[0012] Preferably the collar of the gasket engages both the shaft
of the fastener and the bore wall.
[0013] Preferably the collar of the gasket forms a bond with the
shaft of the fastener and/or the bore wall.
[0014] Preferably the ring forms a bond with the head of the
fastener and the face of the first component.
[0015] The head of the fastener may comprise a non-tapered
button-head, or more preferably the bore comprises a tapered
opening and the head of the fastener comprises a tapered head which
is received in the tapered opening.
[0016] The gasket may be un-reinforced, or more preferably the
gasket further comprises a reinforcing element such as a fabric.
Typically the gasket comprises a matrix-rich region which contains
a lower than average density of reinforcement, for instance on an
outer surface of the gasket.
[0017] Any suitable reinforcing material may be used, for example
glass, carbon, aramid, metal (especially stainless steel) or
polyamide.
[0018] To protect the structure of an aircraft in the event of a
lightning strike, the electrical conductivity through the structure
and across joints needs to be controlled. This is also important to
ensure the safe dissipation of static electricity. In the case of
sealed joints, there is a requirement to prevent voids between the
fastener and the structure which can be heated by high electrical
currents, expand and cause damage to the surrounding structure.
[0019] The current solution for sealing and protecting structure
from lightning strike is to prevent air voids by using wet
assembled sealed joints and to provide a low impedance path between
two surfaces or parts, usually through the use of bonding leads.
However, bonding leads can fail (break) creating a spark hazard,
which is unacceptable particularly in areas of the aircraft
containing fuel vapour. Moreover, a large space envelope is
required to install and maintain bonding leads.
[0020] Optionally the polysulphide material forming the gasket may
be loaded with conductive particles. In this case the gasket will
provide an element of protection from lightning strike by forming
an electrical path between the components without air voids. The
conductive particles may comprise carbon black or metals such as
silver. However carbon black may not be sufficiently conductive and
silver will reduce the mechanical properties of the polysulphide,
especially when at higher concentrations. Therefore most preferably
the conductive particles are carbon nanotubes.
[0021] Optionally the reinforcing material may also be formed by a
conductive fabric, such as metal, for purposes of lightning
protection.
[0022] In order to increase the sealing material that flows along
the shaft of the fastener, the gasket may have a region of
increased thickness towards its inner periphery. This region may
extend only partly round the circumference of the ring (for
instance in a series of discrete locations) or may extend around
the entire circumference of the ring. Typically the region of
increased thickness includes a matrix-rich protrusion which
contains a lower than average density of reinforcement.
[0023] A further aspect of the invention provides a gasket for
sealing a fastener joint, the gasket comprising a ring of sealing
material surrounding a hole for receiving a fastener, the sealing
material comprising an at least partially cured polysulphide
sealant with a region of increased thickness positioned towards the
inner periphery of the ring.
[0024] The gasket is specially adapted for use in the first and
second aspects of the invention, since the region of increased
thickness provides the necessary material to flow along the shaft
of the fastener.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Embodiments of the invention will now be described with
reference to the accompanying drawings, in which:
[0026] FIG. 1 is a plan view of a gasket;
[0027] FIG. 2 is a cross-section through the gasket;
[0028] FIG. 3 is an enlarged cross-section through part of the
gasket;
[0029] FIG. 4 is a cross-sectional view of a joint on an aircaft,
before the sealant material has flowed along the shaft of the
bolt;
[0030] FIG. 5 shows the bolt being pushed into the joint; and
[0031] FIG. 6 shows the joint after the sealant material has flowed
along the shaft of the bolt.
DETAILED DESCRIPTION OF EMBODIMENT(S)
[0032] A gasket 1 shown in FIGS. 1-3 comprises a ring of sealing
material with an outer periphery 2, and an inner periphery 3
surrounding a hole 4.
[0033] The sealing material comprising an at least partially cured
polysulphide sealant 5, and a layer of fabric reinforcement 6 shown
in cross-section in FIGS. 2 and 3. The gasket has a ring-shaped
protrusion 7 which is positioned towards the inner periphery 3 of
the ring, and extends around the entire circumference of the ring
as shown in FIG. 1. The protrusion 7 contains substantially none of
the reinforcing fabric as shown in FIGS. 2 and 3.
[0034] The gasket is manufactured by the following process. First,
a paste of polysulphide material is mixed with a curing agent such
as manganese dioxide. Various suitable sealant materials are
described in EP 1548083 A1, the contents of which is incorporated
herein by reference. By way of example, the material may comprise
Chemetall MC238-A1/2 or PRC-De Soto International PR1770C12.
Optionally the paste of polysulphide material may be filled with
conductive particles, most preferably carbon nanotubes, for
purposes of lightning protection.
[0035] A woven cloth of glass-fibre is then impregnated with the
polysulphide sealant by a conventional calendering process. The
calendering process produces matrix-rich regions 8,9 shown in FIG.
3. Then the sheet is stamped to cut out the ring-shaped profile of
the gasket which is placed between a pair of mould tools shaped to
give the required shape to the protrusion 7. The ring is compressed
between the mould tools and heated to a lightly raised temperature
(no greater than 60.degree. C.) to fully or partially cure the
polysulphide material. Completion of the curing process may occur
before or after assembly of the joint.
[0036] A method of sealing a fastener joint with the gasket 1 is
shown in FIGS. 4-6. First, the gasket 1 is mounted on the tapered
head 10 of a bolt. The shaft 11 of the bolt is then passed through
a pair of components 12, 13 as shown in FIG. 4, and a nut 14 is
screwed onto the threaded distal end 15 of the shaft 11. As the nut
is screwed tight, the gasket engages a tapered opening 16 in the
first component 12 as shown in FIG. 5. At this point the gasket is
un-deformed. As the nut is tightened further; the gasket 1 becomes
compressed between the tapered head 10 of the bolt and the wall of
the tapered opening 16. Unexpectedly, this pressure causes the
polysulphide sealing material in the matrix-rich regions 8,9 and
the protrusion 7 to flow along the shaft 11 of the fastener to form
a cylindrical collar 18 between the shaft 11 and the wall of the
cylindrical bore 19 in the first component 12 as shown in the
left-hand side FIG. 6. The right-hand side of FIG. 6 shows the
gasket in its un-flowed state, for comparison purposes. This can be
contrasted with gaskets formed with polytetrafluoroethylene (PTFE)
which tend to flow outwardly instead of flowing along the shaft
11.
[0037] Conceivably, if the first component 12 is thin then the
sealing material may flow as far as the second component 13. After
a period of time, the sealing material bonds to the opposing
surfaces of the tapered head 10, tapered opening 16, shaft 11 and
the wall of the cylindrical bore 19 to form a fluid-tight seal.
[0038] Although the invention has been described above with
reference to one or more preferred embodiments, it will be
appreciated that various changes or modifications may be made
without departing from the scope of the invention as defined in the
appended claims.
* * * * *