U.S. patent application number 12/592909 was filed with the patent office on 2011-06-09 for method of forming adhesive joint, structural subassembly, and joint construction.
Invention is credited to Clark David Anderson, David Hinman Hinman, Russel Hugh Marvin, Drew M. Rocky, Bret T. Sleicher.
Application Number | 20110131917 12/592909 |
Document ID | / |
Family ID | 44080603 |
Filed Date | 2011-06-09 |
United States Patent
Application |
20110131917 |
Kind Code |
A1 |
Anderson; Clark David ; et
al. |
June 9, 2011 |
Method of forming adhesive joint, structural subassembly, and joint
construction
Abstract
A method of forming an adhesive joint, a structural subassembly,
and a joint construction. The method comprises telescopically
assembling male and female tubular members having slightly
different diameters to cooperatively define a narrow continuous
open-end adhesive chamber between contiguous surfaces of the
assembled members. Four (4) or more centering pins equally
circumaxially spaced about the members are forcefully entered in
the adhesive chambers to equalize spacing between the members
throughout the chamber. A distributing device communicates with the
adhesive chamber for the introduction of adhesive under pressure to
the chamber, thus forming a secure joint. In a fabrication method
for a structural subassembly at least three (3) tubular structural
members are loosely assembled with three (3) joint members each
having at least two cups. Centering pins are forcefully introduced
between contiguous surfaces of the members and cups and a
distribution device encloses the open end of the adhesive chamber.
Adhesive is then introduced between the contiguous surfaces of the
members to form secure joints throughout. A joint construction is
produced in the practice of the method of the invention.
Inventors: |
Anderson; Clark David;
(Barkhamsted, CT) ; Rocky; Drew M.; (Sherman,
CT) ; Sleicher; Bret T.; (Naugatuck, CT) ;
Hinman; David Hinman; (Torrington, CT) ; Marvin;
Russel Hugh; (Goshen, CT) |
Family ID: |
44080603 |
Appl. No.: |
12/592909 |
Filed: |
December 5, 2009 |
Current U.S.
Class: |
52/704 ;
52/745.18; 52/745.2; 52/745.21 |
Current CPC
Class: |
C09J 5/00 20130101; E04B
2001/2451 20130101; E04B 2001/2427 20130101 |
Class at
Publication: |
52/704 ;
52/745.18; 52/745.2; 52/745.21 |
International
Class: |
E04H 12/00 20060101
E04H012/00; E04H 12/34 20060101 E04H012/34; E04B 1/38 20060101
E04B001/38 |
Claims
1. For use in constructing a wind turbine tower; a method of
forming an adhesive joint comprising the steps of telescopically
assembling male and female members having cross sectional
configurations which are similar but slightly different in size so
as to cooperatively define an open end adhesive chamber between
contiguous surfaces of the members, providing centering means which
engage the contiguous surfaces of the assembled members and
substantially equalize spacing between the members throughout the
adhesive chamber, providing an inlet port communicating with the
adhesive chamber, injecting an adhesive through the inlet port to
fill the adhesive chamber substantially uniformly throughout the
area between the members to be joined, and curing the adhesive to
form a secure joint.
2. A method of forming a joint as set forth in claim 1 wherein the
centering means takes the form of at least one locating pin
positioned in the adhesive chamber and engaging the opposing
contiguous surfaces of the adjacent male and female members.
3. A method of forming a joint as set forth in claim 2 wherein at
least one locating pin is positioned in the female member prior to
the telescopic assembly of the male and female members.
4. A method of forming a joint as set forth in claim 2 wherein the
at least one centering and fixing pin is forcefully inserted into
the adhesive chamber and into engagement with the contiguous
surfaces of the male and female members subsequent to the
telescopic assembly of the members whereby to both center the male
member and firmly fix the male and female members relative to each
other.
5. A method of forming a joint as set forth in claim 1 wherein the
centering means comprises at least one elongated integral
longitudinally extending rib on one of the male and female members,
which engages and centers the male member during telescopic
assembly of the members.
6. A method of forming a joint as set forth in claim 1 wherein at
least one short centering means is provided on the surface of one
of the male and female members spaced substantially inwardly from
the mouth of the female member to engage and center the male member
toward the end of the telescopic assembly of the members.
7. A method of forming a joint as set forth in claim 1 wherein the
female member is provided with a shoulder spaced from its open end
and engageable with the free end of the male member to act as a
stop when the latter in inserted into the female member.
8. A method as set forth in claim 1 wherein the female member is
effectively closed beyond the end of the assembled male member so
as to prevent loss of adhesive and yet allow air to escape and
thereby prevent voids in the adhesive.
9. A method as set forth in claim 7 wherein an annular sealing
insert is provided and is disposed between the shoulder and the
inner end of the male member and allows air to pass but serves as a
barrier to adhesive to prevent voids in the latter.
10. A method as set forth in claim 1 wherein an annular sealing
insert is provided and is disposed between the axially extending
surfaces of the male and female members adjacent the inner end of
the male member and allows air to pass and serves as a barrier to
adhesive to prevent voids in the latter.
11. A method as set forth in claim 10 wherein an annular end cap is
provided for the inner end of the male member and mounts the
annular seal with its inner surface spaced radially inwardly from
the end of the radial end surface of the male member, the seal then
being inserted into the mouth of the female member without
distortion which might compromise sealing efficiency.
12. A method as set forth in claim 11 wherein the end cap is
provided with an annular chamfer to direct the same into the mouth
of the female member.
13. A method as set forth in claim 11 wherein the end cap is of a
clear transparent plastic and serves as a visible indicator of
uniform adhesive distribution about the radial end portion of the
male member.
14. A method as set forth in claim 11 wherein the small indicator
openings are provided in the end cap for determining complete
filling of the inner end portion of the adhesive chamber.
15. A method as set forth in claim 11 wherein a deep annular notch
is provided in the annular end cap and wherein a ring seal is
provided in the notch with an outwardly projecting substantially
convex surface in cross-section.
16. A method as set forth in claim 15 wherein the end cap is
provided with an inclined annular lip seal extending outwardly
between radial and axial planes adjacent and toward the convex
surface of the ring seal.
17. A method as set forth in claim 1 wherein a flexible inclined
annular lip seal is provided on the end cap and engages and is
flexed radially inwardly during assembly of the male and female
members, whereby to reside in sealing compression in the assembled
state of the members.
18. A method as set forth in claim 1 wherein the male member is
solid.
19. A method as forth in claim 1 wherein both the male and female
members are tubular.
20. A method as set forth in claim 19 wherein both the male and
female members are thin-walled cylindrical tubular members,
21. A method as set forth in claim 4 wherein at least three
locating pins are provided in substantially equally spaced
relationship around the members.
22. A method as set forth in claim 21 wherein at least three (3)
equally-circumaxially spaced entry notches are provided around the
mouth of the female member each with a gradual chamfer for
directing a locating pin into the adhesive chamber and into
engagement with the male and female members.
23. A method as set forth in claim 20 wherein the members are
thin-walled cylindrical tubular members of galvanized structural
steel.
24. A method as set forth in claim 1 wherein an adhesive
distributing device is positioned about the free end of the female
member and has an inlet port communicating with the adhesive
chamber.
25. A method as set forth in claim 1 wherein an adhesive inlet port
is provided in the female member intermediate its ends and wherein
seals are provided at opposite ends of the adhesive chamber.
26. A method as set forth in claim 1 wherein an annular seal is
provided adjacent the inner end of the male member that allows air
to pass but serves as a barrier to adhesive, and wherein adhesive
is introduced to the adhesive chamber at substantially constant
volumetric flow rate with injection being terminated when a
pressure rise indicates adhesive covering the face of the seal and
a completely full adhesive chamber.
27. A method for fabricating a structural assembly for use in a
wind turbine tower comprising the steps of providing at least three
elongated tubular structural members arranged in spaced
relationship with at least three associated joint members each
having at least one short connecting member differing in diameter
from the tubular structural members, the structural members and
short connecting members thus being adapted for male-female
telescopic assembly each having an annular open end adhesive
chamber therebetween, positioning the structural assembly with the
members and short connecting members in loose male-female
telescopic relationship, providing centering means in each adhesive
chamber to locate the structural members and short connecting
members in substantially uniformly spaced relationship with
resulting adhesive chambers of substantially uniform width
therebetween, providing an inlet port communicating with each
adhesive chamber injecting an adhesive into said inlet port whereby
to fill said adhesive chamber uniformly throughout the area between
the members to be joined, proceeding to second, third and all
remaining joints, and repeating the adhesive injection procedure
and curing the adhesive in all adhesive chambers to form secure
joints throughout.
28. A method for fabricating a structural assembly as set forth in
claim 27 wherein said centering means comprises at least one
locating pin forcefully inserted into each adhesive chamber to
engage contiguous surfaces of the male and female members.
29. A method for fabricating a structural assembly as set forth in
claim 28 wherein at least one short centering means is provided on
at least one of said male and female members spaced substantially
from the mouth of the female member to engage and center the male
member toward the end of the telescopic assembly of the
members.
30. A method for fabricating a structural assembly as set forth in
claim 27 wherein each female member has a shoulder spaced from its
open end engageable with the end of the male member and acting as a
stop when the latter is inserted into the female member.
31. A method as set forth in claim 27 wherein each female member is
effectively closed beyond the end of the assembled male member.
32. A method as set forth in claim 30 wherein an insert is
positioned between the shoulder and the inner end of each male
member and allows air to pass but serves as a barrier to adhesive
loss.
33. A method as set forth in claim 31 wherein an additional seal is
provided adjacent the free end of the female member.
34. A method as set forth in claim 27 wherein both the male and
female members are thin-walled tubular members constructed of
galvanized structural steel.
35. A method as set forth in claim 31 wherein at least three (3)
locating pins are provided and are equally spaced around the
cylindrical tubular members.
36. A method as set forth in claim 27 wherein said structural
members are arranged in angularly displaced closed loop
relationship with each other.
37. A method as set forth in claim 27 wherein a fixture is provided
and wherein said structural members and short connecting means are
initially positioned in loose interconnection and in subassembly
relationship with the aid of the fixture.
38. A method as set forth in claim 27 wherein an annular end cap is
provided for the inner end of the male member and adhesively mounts
an annular seal with its inner surface spaced radially inwardly
from the axial surface of the male member, the seal then being
inserted into the mouth of the female member without rolling up and
other distortion.
39. An adhesive joint as set forth in claim 38 wherein an adhesive
distributing device is positioned about the free end of the female
member and has an inlet port communicating with the adhesive
chamber.
40. For use in a wind turbine tower; an adhesive joint between
telescopically related male and female members having cross
sectional configurations which are similar but slightly different
in size so as to cooperatively define a narrow open end adhesive
chamber between contiguous surfaces of the assembled members, at
least one centering means positioned in the adhesive chamber and
engaging the contiguous surfaces of the two members and
substantially equalizing the space between the members throughout
the chamber, said adhesive chamber being filled with adhesive
uniformly throughout the area between the members to be joined.
41. An adhesive joint as set forth in claim 40 wherein an adhesive
distributing device is positioned about the free end of the female
member and adhesive is introduced through an inlet port
communicating with the adhesive chamber.
42. An adhesive joint as set forth in claim 40 wherein the
centering means takes the form of at least one locating pin in the
adhesive chamber engaging the contiguous surfaces of the male and
female members in a press fit.
43. An adhesive joint as set forth in claim 40 wherein at least one
integral rib comprises the centering means and projects from the
surface of one of the male and female members to engage the
contiguous surface of the male member.
44. An adhesive joint as set forth in claim 40 wherein a centering
means includes at least one short rib on the interior surface of
one of said male and female members spaced substantially from the
mouth of the member to engage and center the male member toward the
end of a telescopic assembly of the members.
45. An adhesive joint as set forth in claim 40 wherein one of the
male and female members has a shoulder spaced from its end
engageable with the end of the opposite member and acting as a stop
when the male member is in inserted into the female member.
46. An adhesive joint as set forth in claim 42 wherein an annular
sealing insert is disposed between the shoulder and the inner end
of the male member and allows air to pass but prevents adhesive
loss.
47. An adhesive joint as set forth in claim 40 wherein an annular
sealing insert is disposed about the male member and in engagement
with the axially extending surface of the female member adjacent
the end of the male member and allows air to pass but prevents
adhesive loss.
48. An adhesive joint as set forth in claim 40 wherein both male
and female are thin thin-walled tubular members of galvanized
structural steel.
49. A method as set forth in claim 40 wherein an annular end cap is
provided for the inner end of the male member and adhesively mounts
an annular seal with its inner surface spaced radially inwardly
from the end of the radial end surface of the male member, the seal
thus being inserted into the mouth of the female member without
rolling up and other distortion.
50. A method as set forth in claim 49 wherein a deep annular notch
is provided in the annular end cap and wherein a ring seal is
disposed in the notch with an outwardly projecting substantially
convex surface.
51. A method as set forth in claim 49 wherein the end cap is
provided with an inclined annular lip seal adjacent the convex
surface of the ring seal.
52. A method as set forth in claim 40 wherein a flexible inclined
annular lip seal is provided on an end cap for the male member and
engages and is flexed radially inwardly during assembly of the male
and female members whereby to reside in sealing compression in the
assembled state of the members.
Description
BACKGROUND OF THE INVENTION
[0001] Adhesive joints have been used in the past and while perhaps
generally satisfactory have not been wholly satisfactory
particularly in lightweight high strength structural applications.
Two fundamental problems are encountered. One is the maintenance of
precise relative positions of the members to be joined during the
introduction and curing of the adhesive. At the present time this
problem is solved by the use of extensive fixturing devices for
securely holding the members during the application and curing of
the adhesive. This procedure is not practical, however, for the
high volume production of structural joints. A wind turbine tower
with extensive structural steel lattice or truss work, for example,
may involve hundreds and even thousands of joints.
[0002] The second problem resides in the provision of adhesive of
uniform thickness throughout the area between the members to be
joined. One current procedure involves the introduction of glass
beads of a known diameter to the adhesive to provide uniform
spacing but this of course reduces the amount of adhesive actively
securing the joint and the beads may also introduce areas of stress
concentration further reducing joint strength.
[0003] In view of the foregoing, it is the general object of the
present invention to provide a method of forming an improved
adhesive joint, a structural subassembly employing the method, and
a joint construction all employing a self fixturing feature which
overcomes the disadvantages of current practice and which is
particularly well suited to high volume production as in wind
turbine towers.
SUMMARY OF THE INVENTION
[0004] In fulfillment of the forgoing object and in accordance with
the present invention, a method is provided which is particularly
well suited to the fabrication of wind turbine towers of galvanized
steel construction but which also has broad general application.
The method contemplates the forming of an adhesive joint between
telescopically assembled male and female members having cross
sectional configurations which are similar but slightly different
in size so as to cooperatively define a narrow continuous open-end
adhesive chamber between contiguous surfaces of the assembled
members. In the presently preferred form of the method of the
invention, at least one and preferably four or more locating pins
are inserted under pressure through the open end of the adhesive
chamber into engagement with the contiguous surfaces of the two
members and in spaced relationship about the members to equalize
spacing between the same throughout the adhesive chamber. An
adhesive distributing device provided with an inlet port encloses
and communicates with the open end of the adhesive chamber. An
adhesive is then injected through the inlet port preferably under
pressure to fill the adhesive chamber uniformly throughout between
the members to be joined. The adhesive is then cured to form a
secure joint.
[0005] Preferably, a shoulder is provided on one of the members and
preferably on the female member spaced from its open end and is
engageable with the free end of the male member to act as a stop
when the latter is inserted into the female member. A small insert
of open cell foam positioned between the shoulder and the end of
the male member allows air to pass but serves as a barrier to the
adhesive and thus prevents the formation of air pockets or voids in
the adhesive. In addition, this arrangement accommodates the use of
a superior adhesive chamber filling process. Conventional gluing
processes inject adhesive at a constant pressure and stop when a
pre-selected volume has been injected. When porous open cell foam
seals or other air permeable sealing arrangements are employed
adhesive can be injected at a constant flow rate and terminated
when a sharp rise in pressure is encountered. This is due to air at
first passing through the seal and thereafter stopping abruptly
when the seal is covered with adhesive throughout its surface area
indicating a completely full adhesive chamber. This process insures
complete filling of the adhesive chamber even though there may be
substantial variation in volume of the chamber due to tolerances
and other dimensional variations in manufactured parts.
[0006] The male member may be either solid or tubular and the
female tubular or both members may be tubular, the term tubular
referring to any generally hollow member which may be circular,
oval, rectangular, triangular or of almost any cross sectional
configuration. In the case of the wind turbine tower application of
the invention, relatively thin walled tubing of circular and
rectangular cross sections are employed in the form of galvanized
structural steel.
[0007] As mentioned, the method of the invention is particularly
well suited to the construction of subassemblies for wind turbine
towers. Three or more elongated structural members of a subassembly
may be loosely telescopically assembled to form loose joints with
three or more connecting joint members each having at least one cup
slightly different in diameter from that of the structural members.
Centering means in the form of one or more and preferably four or
five locating pins may then be inserted in each loose joint to
firmly locate the structural and joint members relative to each
other and to simultaneously provide adhesive chambers of uniform
width at each joint. Employing distributing devices at each joint
the adhesive chambers may then be filled with adhesive under
pressure and cured to complete the subassembly.
[0008] The joint construction of the present invention is of course
the product of the method of the invention.
DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a somewhat schematic sectional view of a joint
construction of the present invention,
[0010] FIG. 2 is schematic sectional view taken generally as
indicated at 2-2 in FIG. 1,
[0011] FIG. 3 is a view of a small insert used between the male
member and an adjacent shoulder on the female member,
[0012] FIG. 4 is a view showing a locating pin employed as a
self-fixturing means,
[0013] FIG. 5 is a view showing a pair of locating pins installed
prior to the telescopic assembly of the male and female
members,
[0014] FIG. 6 is a view of a female member with integral ribs
employed as a centering means,
[0015] FIG. 7 is a fragmentary cross-sectional enlarged view
showing a notch and chamfer in an open end of a female member, the
locating pins thus being guided into an adjacent adhesive
chamber,
[0016] FIG. 8 is a fragmentary cross-sectional enlarged view
showing a short centering means formed integrally on the interior
surface of a female member in spaced relationship with the mouth of
the member, the centering means serving to center the free end of a
male member entered in the female member,
[0017] FIG. 9 is a schematic perspective showing an adhesive
distributing device mounted on an assembled male-female joint,
[0018] FIG. 10 is a sectional view through the adhesive
distributing device of FIG. 9,
[0019] FIG. 11 is a schematic view showing a subassembly of a wind
turbine tower structure employing the method and joint construction
of the invention,
[0020] FIG. 12 is a fragmentary enlarged view showing a small
annular insert at the inner end of the adhesive chamber around and
in engagement with the outer surface of the male member and with
and in engagement with the inner surface of the female member,
[0021] FIG. 13 is a fragmentary enlarged view showing an
alternative embodiment of the invention with an adhesive port
defined in a female member at an intermediate location and with
annular seals at opposite ends of an adhesive chamber,
[0022] FIG. 14 is a fragmentary cross-sectional through an
assembled joint comprising male and female members and an end cap
mounted on the end of the male member and carrying an annular
seal,
[0023] FIG. 15 is a fragmentary cross-sectional view similar to
FIG. 14 but showing a slightly different end cap and seal
arrangement,
[0024] FIG. 16 is a fragmentary cross-sectional view taken as
indicated at 16, 16 in FIG. 15 and showing a plurality of sight
holes spaced circumaxially about the end cap,
[0025] FIG. 17 is a fragmentary cross-sectional view similar to
FIGS. 14 and 15 but showing an annular ring seal in a deep notch in
an end cap,
[0026] FIG. 18 is a fragmentary cross-sectional view similar to
FIG. 17 but showing a ring seal with a small flexible lip seal on
the end cap.
[0027] FIG. 19 is a fragmentary cross-sectional view similar to
FIGS. 17 and 18 but showing a flexible lip seal on the end cap
without the ring seal of FIGS. 17 and 18, and
[0028] FIG. 20 is a fragmentary cross-sectional view similar to
FIGS. 17 and 18 but showing a dovetail ring seal in a dovetail
notch.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0029] Referring particularly to FIGS. 1 and 2, an adhesive joint
construction indicated generally at 10 includes telescopically
assembled male and female members 12 and 14 which are similar in
cross sectional configuration but which are different in size so as
to cooperatively define a narrow continuous open-end adhesive
chamber 16. The members 12 and 14 are both tubular with circular
cross sections as shown but as mentioned above a wide variety of
types of tubular and other male and female members may benefit from
the teaching of the present invention. As is also mentioned above
it is most important to maintain uniform thickness of the adhesive
throughout the chamber 16 without pockets or voids in order to
provide an efficient low cost joint of high structural integrity
and lightweight.
[0030] In accordance with the method of the present invention, the
male and female members are designed to provide adhesive chamber 16
of uniform width throughout when the members are telescopically
assembled and small locating pins 18,18 are thereafter employed to
fix the relative positions of the members and precisely establish
the width of the adhesive chamber 16. At least one pin 18 is
provided and as shown, four (4) equally circumaxially spaced pins
18,18 are inserted into the adhesive chamber 16 through its open
end to positively fix the position of the members and the width of
the chamber 16. The pins 18,18 are preferably inserted under
pressure as with a pneumatic gun and thus serve a self-fixturing
function for the joint.
[0031] As best illustrated in FIGS. 2 and 7, a series of small
notches 19, 19 may be provided in equally circumaxial spaced
relationship around the mouth of the female member 14. Each notch
19 has a shallow chamfer 21 at its inner end which is adapted to
direct a locating pin 18 into an adhesive chamber in pressure
engagement with the contiguous surfaces of the male and female
members 12,14. Alternatively, locating pins such as 23,23 best
shown in FIG. 5 may be employed as centering means and may be
positioned in the mouth of the female member 14 prior to assembly
of the same with the male member 12. A connecting loop 25
facilitates handling the pair of the locating pins 23,23.
[0032] In FIG. 6 a second alternative embodiment of centering means
is shown with integral ribs 27, 27 formed in circumaxially spaced
relationship on the interior surface of a rectangular tubular
member 29 with two (2) ribs 27, 27 on one side of the member 29
[0033] Still further, short centering means 31 may comprise a
single annular element or a number of individual ribs on the
interior surface of the female member 14 spaced inwardly from the
mouth of the member as best shown in FIG. 8. The annular element or
ribs 31 serve as auxiliary centering means and engage and center
the free end of a male member 12 as it reaches the end of its
travel during assembly of the male and female members. The annular
element or ribs 31 may be employed with any of the foregoing
centering means.
[0034] With the adhesive chamber 16 properly sized and the members
12 and 14 secured in fixed positions by the pins 18,18, a
distributing device 22 is positioned about open end 20 of the
adhesive chamber 16, and as shown in FIGS. 9 and 10 encloses and
has an inlet port 19 which communicates with the same for the
introduction of an adhesive under pressure. Various adhesives may
be employed but Loctite H8600 is presently preferred in an
illustrative embodiment for joining the galvanized structural steel
employed in wind turbine tower construction. A relatively low
viscosity adhesive is of course preferred for rapid insertion in a
high production environment. A uniform adhesive thickness less than
fifty thousandths of an inch is found to provide the high strength
low weight results desired with galvanized structural steel.
[0035] As mentioned above, the use of open cell foam seals
accommodates an adhesive filling procedure based on pressure
control and termination resulting in a completely filled adhesive
chamber.
[0036] It should also be noted that the distributing device 22 may
serve independently as a centering means avoiding the need for
substantially all other centering means.
[0037] As mentioned, the prevention of voids in the adhesive is
also important and a small open cell foam insert 24, FIGS. 3 and 8,
captured and compressed between an annular shoulder 26 on the
interior wall of the female member 14, and the inner end of the
male member 12 prevents the entrapment of air and resulting pockets
or voids. The insert is perforate to air and readily allows the
same to pass but serves as an effective barrier to adhesive.
[0038] In FIG. 12 an annular seal 39 is shown about the inner end
of a male member as an alternative embodiment. The seal 39 may be
of open cell foam as above and also serves a preliminary centering
function as well as a sealing function preventing the adhesive from
escaping while allowing the air to pass.
[0039] Referring now to FIG. 11, it will be observed that three (3)
elongated structural members 28,28 form a closed loop subassembly
indicated generally at 30, which may be a part of a truss type wind
turbine tower. Employing the teaching of the present method, the
members 28,28 may be assembled as shown with their end portions
entered loosely in cups 32,32, which form a part of connecting or
joint members 34,34. Locating pins such as 18,18, not shown, may
then be inserted circumaxially about the ends of the members 28,28
into adhesive chambers within the cups 32,32 in a self-fixturing
operation. This is followed by positioning of adhesive distributing
devices about the joints and the introduction of adhesive to fill
the adhesive chambers thus completing the subassembly.
[0040] FIG. 13 illustrates an alternative embodiment of the
invention with an adhesive port 40 formed for example by casting in
a female member 42 at an intermediate location and communicating
with an adhesive chamber 44. At opposite ends of the adhesive
chamber 44 seals 46,46 are provided and may take the form of
annular compressed open cell foam members as above.
[0041] FIG. 14 shows an assembled adhesive joint comprising male
and female members 48 and 50 and end cap 52 mounted on the inner
end of male member 48 and an annular seal 54 secured to the end
cap. The inner annular surface 56 of the annular seal 54 is spaced
inwardly from the external surface of the cap 52 and/or the surface
58 of the male member 48 and is adhesively attached to the cap 52.
Thus, the cap 52 serves to protect the seal 54 on insertion of the
insert and seal through the mouth of the female member 50 and axial
sliding movement thereafter urging the male member to the assembled
position shown in FIG. 14. This allows relative axial movement of
the male and female members without loss of sealing efficiency. It
should also be noted that the end cap 52 may serve as a centering
means.
[0042] Referring to FIG. 15, a male member 48a and female member
50a are shown assembled with an end cap 52a mounted on the male
member 48a and an annular seal 54a mounted on the end cap. The end
cap 52a has an annular chamfer 60 at its free end portion which
assists in aligning the cap during entry through the mouth of the
female member 58.
[0043] The cap 52a has a small annular portion adjacent the end of
the male member 48a which is externally exposed to the inner end of
an adhesive chamber 64. Thus, when the cap is constructed of a
transparent material, an annular indicator or sight opening is
provided so as to visually ascertain whether the adhesive is
distributed completely around the chamber 64.
[0044] In FIG. 17 an end cap 70 is provided with a somewhat deeper
annular notch 72 than in prior configurations. An annular O-ring
seal 74 is disposed in the notch and has only a small convex
portion thereof exposed radially outwardly from the mouth of the
notch. Engagement of the leading edge of the female member with the
convex surface urges the annular O-ring seal radially inwardly into
its notch to avoid excessive distortion of the same. The O-ring
seal is preferably of compressible open cell foam.
[0045] FIG. 18 shows a design which may be identical to that of
FIG. 17 except for the provision of a small flexible annular lip
seal 76 which is formed on the end cap and which is adjacent the
entrance surface of the projecting convex portion of the O-ring
seal 74a. As will be apparent, the lip seal 76 protects the ring
seal 74a during entrance of the male member through the mouth of
the female member and prevents distortion of the seal. An air
escape opening 78 may be provided or, alternatively, a series of
circumaxially spaced small air escape slits may be provided in the
lip seal 76.
[0046] FIG. 19 illustrates a configuration wherein a small flexible
lip seal 76a on the end cap serves as the sole adhesive sealing
means and may also serve as a centering means. The lip seal 76a is
flexed radially inwardly during entry of the male member through
the mouth of the female member and resides in compression in the
assembled position of the members. A circumaxial series of small
axial openings 78a,78a provide for the escape of air and a minimal
amount of adhesive and may also serve as sight holes.
Alternatively, the seal 76a may be provided with a series of air
escape slits as above.
[0047] Finally, it will be apparent for the foregoing that various
cross sectional shapes may be employed for an O-ring seal in a
notch such as the notch 72a in FIG. 20. For example, a convex outer
surface may be provided for an O-ring seal 74b in FIG. 20 with the
inner portion of the seal taking a rectangular configuration or
alternatively, a dovetailed configuration may be utilized for
secure retention of the inner portion of the seal as illustrated in
FIG. 20.
[0048] End cap 52b in FIG. 20 may be opaque with small sight
openings provided at 66, 66 in a circumaxial array as illustrated
in FIG. 16.
[0049] As will be apparent from the foregoing a relatively simple
self-fixturing procedure has been devised as part of a highly
efficient overall method providing a high strength low weight joint
construction particularly well suited to high production joint
formation as required in wind turbine tower fabrication at economic
advantage. Substantial savings are realized in both material and
labor costs as compared with conventional flange-bolt type joints
as well as prior art adhesive joints.
* * * * *