U.S. patent application number 12/287917 was filed with the patent office on 2009-02-19 for wind turbine installation comprising an apparatus for protection of anchor bolts and method of installation.
Invention is credited to Norman L. Tooman.
Application Number | 20090044482 12/287917 |
Document ID | / |
Family ID | 40361868 |
Filed Date | 2009-02-19 |
United States Patent
Application |
20090044482 |
Kind Code |
A1 |
Tooman; Norman L. |
February 19, 2009 |
Wind turbine installation comprising an apparatus for protection of
anchor bolts and method of installation
Abstract
An apparatus for use in providing a level grout surface for
placement of a wind turbine tower flange, the apparatus comprising
a template member levelly suspended on the anchor bolts above the
grout trough, wherein the template member comprises a surface to
which grout will not adhere. The template member can comprise an
upper layer and a lower grout engagement layer, wherein the grout
engagement layer comprises a surface to which grout will not
adhere. The upper layer can comprise a metallic layer, and the
lower layer can comprise a plastic layer, wherein the upper layer
and the lower layer are bonded together. The lower layer can
comprise polypropylene. The means of bonding are selected from the
group consisting of mechanical bonding, thermal bonding and
chemical bonding. The grout can comprise an epoxy grout. The
template member can be suspended through the use of magnetic nuts
or the use of a rotating sleeve. The template member can comprise a
plurality of sections, and can comprise a circular form.
Inventors: |
Tooman; Norman L.;
(Bakersfield, CA) |
Correspondence
Address: |
KLEIN, DENATALE, GOLDNER, COOPER et. al.
P.O. BOX 11172
BAKERSFIELD
CA
93389-1172
US
|
Family ID: |
40361868 |
Appl. No.: |
12/287917 |
Filed: |
October 14, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12012137 |
Jan 30, 2008 |
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12287917 |
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60898452 |
Jan 30, 2007 |
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60905399 |
Mar 5, 2007 |
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Current U.S.
Class: |
52/699 ;
52/742.15 |
Current CPC
Class: |
F03D 13/22 20160501;
Y02E 10/728 20130101; E02D 27/42 20130101; Y02E 10/72 20130101;
E04H 12/085 20130101 |
Class at
Publication: |
52/699 ;
52/742.15 |
International
Class: |
E02D 27/32 20060101
E02D027/32; E04H 12/00 20060101 E04H012/00 |
Claims
1. An apparatus for use in providing a level grout surface for
placement of a wind turbine tower flange wherein the wind tower
flange supports and stabilizes a wind turbine tower, the wind
turbine tower flange installed on a foundation comprising a
concrete base, a grout trough formed in the cement base for the
placement of a grout used to support the wind turbine flange, and a
plurality of upwardly disposed anchor bolts extending through the
grout, wherein the anchor bolts retain and support the wind turbine
flange, the apparatus comprising: a template member levelly
suspended on the anchor bolts above the grout trough, wherein said
template member comprises a surface to which grout will not
adhere.
2. The apparatus of claim 1 wherein said template member comprises
an upper layer and a lower grout engagement layer, wherein said
grout engagement layer comprises said surface to which grout will
not adhere.
3. The apparatus of claim 2 wherein said upper layer comprises a
metallic layer, and said lower layer comprises a plastic layer,
wherein the upper layer and the lower layer are bonded together by
a bonding means.
4. The apparatus of claim 3 wherein the lower layer is
polypropylene.
5. The apparatus of claim 3 wherein the bonding means are selected
from the group consisting of mechanical bonding, thermal bonding
and chemical bonding.
6. The apparatus of claim 1 wherein the grout is an epoxy
grout.
7. The apparatus of claim 3 wherein the template member is
suspended by one or more nuts made up on respective anchor bolts,
the bottom of each nut comprising a magnetic substance which
adheres to the metallic surface.
8. The apparatus of claim 1 wherein the template member is
suspended through the use of one or more rotating sleeves made up
on the respective anchor bolts, wherein said sleeve extends through
said template member, said sleeve further comprising a support
member, said support member in rotatable engagement with said
template member.
9. The apparatus of claim 1 wherein the template member comprises a
plurality of sections.
10. The apparatus of claim 1 wherein the template member comprises
a circular form.
11. An apparatus for use in leveling a wind turbine tower flange
installed on a foundation comprising a plurality of upwardly
disposed anchor bolts, the apparatus comprising: a template member
and a plurality of anchor bolt engagement means, the anchor bolt
engagement means comprising a means for leveling said template
member relative to the anchor bolts.
12. The apparatus of claim 11 wherein the anchor bolt engagement
means are one or more nuts made up on respective anchor bolts, the
bottom of each nut comprising a magnetic substance which adheres to
the metallic surface.
13. The apparatus of claim 11 wherein the anchor bolt engagement
means are one or more rotating sleeves made up on the respective
anchor bolts, wherein said sleeve extends through said template
member, said sleeve further comprising a support member, said
support member in rotatable engagement with said template
member.
14. The apparatus of claim 11 wherein the template member comprises
a plurality of sections.
15. A method for levelly installing a wind turbine tower onto a
wind turbine foundation, the method comprising the steps of:
installing an anchor bolt assembly using a circular template to
lift said anchor bolt assembly and place said anchor bolt assembly
into an excavation and pouring concrete to form a foundation;
removing said circular template from the foundation thereby
creating a grout trough; suspending a template member above said
grout trough using suspension means attached to said anchor bolts;
leveling said template member; introducing a grout into the space
defined by said template member and said grout trough and allowing
said grout to cure; removing said template member; and installing
the wind turbine flange.
16. The method of claim 15 wherein said template member comprises
an upper metallic layer and a lower layer to which grout will not
adhere.
17. The method of claim 15 wherein said grout comprises an epoxy
grout.
18. The method of claim 16 wherein said suspension means are one or
more nuts made up on respective anchor bolts, the bottom of each
nut comprising a magnetic substance which adheres to the metallic
surface.
19. The method of claim 15 wherein said suspension means are one or
more rotating sleeves made up on the respective anchor bolts,
wherein said sleeve extends through said template member, said
sleeve further comprising a support member, said support member in
rotatable engagement with said template member.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation-in-part of U.S. application Ser. No.
12/012,137 filed on Jan. 30, 2008, which application claimed
priority to U.S. Provision Application 60/898,452 filed on Jan. 30,
2007 and U.S. Provisional Application No. 60/905,399 filed on Mar.
5, 2007, for which applications this inventor claims domestic
priority.
BACKGROUND OF THE INVENTION
[0002] This invention generally relates to wind turbines, and
anchoring devices, such as bolts, which are used in the foundations
of wind turbines because of the high overturning moments to which
wind turbines are subjected. The invention more specifically
relates to a plastic bolt sleeve used in combination with a
threaded anchor, where the plastic sleeve is plastically deformed
or "crimped" onto a portion of the threads of the bolt. The
invention further discloses methods and devices for crimping the
sleeve onto a portion of the bolt threads. Among other benefits,
the crimped bolt sleeve protects the anchor bolts from moisture and
resulting corrosive attack and, when utilized with the disclosed
template member, allows for the use of high compressive strength,
low viscosity grouts, such as epoxy grout, to be used in the
construction of the wind turbine foundation. The use of the
template member obviates the need for a crane to place and level
the foundation flange prior to the grout setting and before the
grout has cured and reached its full strength. This results in less
time spent rigging the crane as the foundation flange may be set
and the turbine tower placed in a single crane deployment.
[0003] The bolts used for anchoring wind turbines may either be set
in concrete or drilled into the rock. The integrity of the
foundation of a wind turbine is subject to failure if the anchor
bolts are not adequately protected. In particular, anchors are
subject to corrosive attack caused by the accumulation of water or
other electrolytes in the anchoring hole which results in the
creation of a corrosion cell. As described below, the practices
employed in preparing the foundation for a wind turbine often
create an environment in which the anchor bolt is exposed to water
or other liquid.
[0004] By way of background for wind turbine foundations, U.S. Pat.
Nos. 5,586,417 and 5,826,387, both by Henderson, disclose a pier
foundation "which can be poured-on-site monolithically and is of
cylindrical construction with many post-tensioned anchor bolts
which maintain the poured portion of the foundation under heavy
compression, even during periods when the foundation may be subject
to high overturning moment." Henderson's foundation is preferably
in the shape of a cylinder, having an outer boundary shell and an
inner boundary shell each formed of corrugated metal pipe which are
set within an excavation.
[0005] In the fabrication of foundations for wind turbines,
elongated high strength steel bolts, generally fashioned from
11/4'' (#10) rebar material or 13/8'' (#11) rebar material are set
within the foundation excavation and concrete is poured into the
excavation such that the bolts extend vertically up through the
concrete from a peripheral anchor plate or ring near the bottom of
the cylinder to a peripheral connecting plate or flange at the base
of the wind turbine tower. The bolts are typically threaded at the
top and bottom ends for a length of approximately 24 inches. The
bolts are largely contained within hollow sleeves made of PVC which
prevent adhesion of the concrete to the bolts. The sleeves are
typically installed prior to delivery of the bolts to the job site,
and nuts must be placed on each end of the anchor bolt to retain
the PVC sleeve on the anchor bolt material.
[0006] Henderson further discloses the post-stressing of the
concrete in great compression by tightening the high strength bolts
to provide heavy tension from the heavy top flange (i.e, the flange
at the base of the wind turbine) through which the bolts pass to
the anchor plate or ring at the bottom of the foundation, thereby
placing the entire foundation from the heavy top plate or flange to
the lower anchor plate or ring under high unit compression loading.
The nuts on the bolts are tightened so as to apply tension to the
bolts exceeding the maximum expected overturning force of the wind
turbine tower structure on the foundation. Therefore, the entire
foundation withstands various loads with the concrete always in
compression and the bolts always in static tension. Because the
bolts are each largely contained within a PVC sleeve, each bolt is
free to move within its sleeve as the bolts are tensioned by
tightening the nuts abutting the top flange. Steps are typically
taken before the concrete is poured to seal the tops of the PVC
sleeves to prevent the flow of concrete into the sleeves, such as
wrapping duct tape around the tops of the sleeves. This can be a
time-consuming process.
[0007] Based upon the discussion above, it is clear that the
integrity of this type of foundation is dependent upon the
integrity of the anchor bolts--the failure of a bolt creates a
stress riser on the remaining bolts, leading to the potential
failure of the entire foundation. The integrity of the steel anchor
bolts can be compromised by corrosive attack. As described above,
according to the current practice each anchor bolt is enclosed for
most of its length within a PVC sleeve. However, because the
outside diameter of the PVC sleeve is too large for the sleeve to
enter the bolt hole of the flange of the tower structure, the
sleeve typically terminates at approximately the top of the
concrete foundation, with the bare metal of the anchor bolt
extending above the sleeve, where the bolts extend through the
flange and have a nut and bolt cap installed on the top side of the
flange.
[0008] The tower flange is usually set on a grout base which
overlies the concrete foundation. The grout base is placed within a
circular "grout trough" which is formed by the pouring of the
concrete foundation around a circular template. This circular
template is utilized to collectively lift and place the anchor bolt
assembly within the excavation prepared for the foundation. As with
the holes of the flange of the tower base, the bolt holes in the
circular template are sized to accommodate the bolt diameter, but
not the diameter of the PVC sleeve, so the tops of the bolt sleeves
will generally be flush with the bottom of the grout trough formed
by the circular template.
[0009] In order to prevent dehydration of the grout--thus adversely
impacting the grout strength--it is a common practice to place
water within the grout trough prior to the pouring of the grout to
keep the grout properly hydrated during the curing process.
However, water placed in the trough will gravitate into the ends of
the PVC sleeves which are flush with the bottom of the grout
trough. In the current installation practice, a foam sleeve is
typically placed around a portion of each bare bolt extending above
the bottom of the grout trough, with each foam sleeve held in place
with duct tape. The length (or height) of the foam sleeve is sized
to extend above the anticipated thickness of the grout layer within
the grout trough. In the known practice, the tower flange is set on
the grout before the grout sets so that the tower base may be
leveled. It is hoped that the foam sleeve will prevent grout from
adhering to the body of the bolt, such that when the grout fully
cures the bolt may be tensioned and slide through the foam sleeve
without damage to the grout. However, in reality the foam sleeve is
likely so deformed by the flange of the tower base that the bolts
will not slide freely through the sleeves once the grout cures.
[0010] In particular, the use of the template member would
eliminate the need for leveling shims and allow the grout to be
poured and adequately cure before setting the flange onto the
grout, as opposed to the current practice of setting and leveling
the tower flange before the grout cures. The current practice
requires the service of a high capacity crane for the initial
setting of the tower flange and subsequently for the assembly of
the complete turbine. However, if the tower flange can be placed at
the same time as the other turbine tower components, only a single
use of the crane is required, resulting in less rigging up and
rigging down time at each turbine tower installation.
[0011] Once the tower has been installed and a nut and bolt cap
installed on the bolt ends extending above the tower flange, the
annulus between the bolt and PVC is sealed. However, during the
known installation method, the annulus between the bolt and the PVC
sleeve is open thereby providing a pathway for water and other
fluids to enter the annulus and be trapped between the PVC sleeve
and the metallic bolt, forming a corrosion cell. Because of this
opening, steps are usually taken to protect the bolt from corrosive
attack and/or to seal the sleeve-bolt annulus during installation.
Unfortunately, the currently practiced installation procedure
aggravates the situation, because, as described above, the
procedure typically includes pouring water in the grout trough to
allow the grout to cure. This practice allows water to accumulate
at the top of the PVC sleeve, and potentially migrate into the
sleeve-bolt annulus.
[0012] The initial attempt at solving the anchor bolt corrosion
problem was to paint the anchor bolts along the entire length.
However, this solution is labor intensive and does not prevent
liquid accumulation around the anchors. In addition, this
protection method requires that the anchors be repainted
periodically, as well as after re-tensioning the anchor if required
in the particular application. The currently practiced method of
protecting the anchor bolts is to seal the annulus between the top
of the PVC sleeve and the bolt with a sealant, such as a silicon
gel.
[0013] As discussed above, the current practice also includes
placing foam or other material around the portion of the bolt
extending above the PVC sleeve, so as to prevent adhesion of the
grout to the bolt and to block the migration of water into the
sleeve-bolt annulus. Typically, foam cylinders with longitudinal
slits are placed around the bolts, with duct tape wrapped around
each cylinder, and the cylinder pushed downwardly into contact with
the top of the PVC sleeve. However, with the large number of bolts
utilized in these types of foundations, it is time consuming and
difficult to seal the top of each PVC sleeve with sealant and to
install the foam cylinders or similar devices. If hurried, the
annulus may not be adequately sealed to prevent the intrusion of
water into the PVC-bolt annulus. Moreover, once the tower base
flange is set upon the foam cylinders, the cylinders are greatly
deformed. It is not unlikely that when the anchor bolts are
tensioned, the bolt does not slide through the foam cylinder, but
that the deformed foam cylinder moves within the grout, potentially
damaging the integrity of the grout. The PVC sleeves, because of
the outside diameter, displace, in totality, a significant volume
of concrete in the foundation, thereby reducing the overall
compressive strength of the foundation. Likewise, the use of the
foam cylinders around the anchor bolts in the grout trough
displaces a significant volume of grout, and thereby reduces the
compressive strength of the flange foundation.
SUMMARY OF THE INVENTION
[0014] The present application is directed toward a method and
apparatus which addresses the problems identified above. In
embodiments of the disclosed invention, rather than utilizing PVC
sleeves which terminate at the bottom of the grout trough, the
present invention comprises anchor bolts comprising a sheath or
sleeve which extends above the grout trough and, if desired, may
partially extend inside the base flange of the wind turbine base.
The sleeve may be manufactured from polypropylene, polyethylene or
other materials having satisfactory mechanical properties,
primarily that the material be capable of withstanding sufficient
plastic deformation to cause the material to conform to the shape
of the threads of the anchor bolts without failing. The term
"polypropylene" when used below, not only includes polypropylene
materials, but other plastic materials having mechanical properties
which allow those materials to be substituted for polypropylene. In
the present application, each anchor bolt comprises a polypropylene
sleeve in which a portion of the sleeve is "swaged" onto a portion
of the threads of the bolt thereby creating a mechanical seal
between the interior of the sleeve and the threads of the bolt. For
purposes of distinguishing the presently disclosed sleeve from the
prior art sleeves, the presently disclosed sleeve is hereinafter
referred to as the "crimped sleeve", although it is to be
appreciated that only a portion of the sleeve actually comprises
crimping or swaging.
[0015] The use of the polypropylene sleeve and the swaging of the
sleeve onto a portion of the bolt threads accomplishes several
improvements over the known apparatus and methods. The bolt package
(i.e. a bolt/sleeve combination) has an overall diameter less than
the overall diameter of the currently utilized bolt-PVC sleeve
combination. This reduced diameter allows the bolt and crimped
sleeve to extend through the bolt holes of the circular template,
and into the bolt holes of the tower flange, which under the known
apparatus and method, only a sleeveless bolt would extend. Because
the crimped sleeve extends above the top of the grout trough, the
encased bolts will not be exposed to water placed within the grout
trough. Moreover, because a seal is formed between the top of the
crimped sleeve and a portion of the threads of the bolt, access to
the annulus between the bolt and the crimped sleeve is either
eliminated or substantially reduced, thereby preventing or greatly
limiting the axial migration of water or other electrolytes along
the length of the bolt. In addition, because the top of the crimped
sleeve extends above the level of the grout, the crimped sleeve
prevents adhesion of the grout to the bolt, thereby allowing the
bolt to move relative to the grout.
[0016] The disclosed apparatus provides a template member that
comprises a surface to which grout will not adhere. The template
member is suspended by the anchor bolts, and is leveled across the
grout trough. Once the template member is leveled, either by the
use of a laser level or a conventionally leveling means, grout is
added to the space defined by the template member and the grout
trough. The grout may be introducing into the trough through fill
holes that extend through the template member. The grout is placed
into the grout trough until the grout reaches the surface of the
lower layer of the template member across the entirety of the grout
trough. The template may then be removed and the grout allowed to
cure, or the template may be left in place atop the grout until the
grout has cured, depending upon the environmental conditions
present at the time.
[0017] The template member may comprise an upper layer and a lower
layer, and the lower layer comprises a surface to which grout will
not adhere. The layers can be bonded together, and the bonding
means can be thermal, chemical or mechanical bonding. The upper
layer may comprise a metallic layer. The lower layer may comprise a
plastic layer, and the plastic layer may comprise polyethylene.
[0018] The template member utilized in one embodiment of the
disclosed device may be sectional, and can be placed sequentially
around the grout trough and leveled. By placing the template member
over the anchor bolts and then leveling the template member, the
top surface of the grout placed into the area defined by the grout
trough and the template member is thereby leveled. When the grout
cures, the tower flange is installed on a level surface. No shims
or blocks are required using this method to obtain a level
foundation for the tower flange, as required in the known
method.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 shows the base of a wind turbine which might utilize
embodiments of the disclosed apparatus and method.
[0020] FIG. 2 shows a bolt assembly utilized for the foundation of
a wind turbine being lowered into an excavation for the
foundation.
[0021] FIG. 3 shows a detailed view of a portion of the grout
trough prior to the placement of the tower base flange, showing the
use of foam sleeves for preventing adhesion of grout onto each bolt
body, and the use of a spacer block for leveling the tower
base.
[0022] FIG. 4 shows a front view of a portion of a tower
foundation, with the tower base flange beginning to be lowered onto
the anchor bolts.
[0023] FIG. 5 shows a cross section of a portion of the base
flange, grout, and PVC sleeve of a prior art anchor bolt
installation.
[0024] FIG. 6 shows a cross section of a portion of the base
flange, grout, and sleeve of an embodiment of the present
invention.
[0025] FIG. 7 shows a portion of an embodiment of the disclosed
crimped sleeve, showing how the sleeve is swaged around some of the
threads of the anchor bolt.
[0026] FIG. 8 shows an embodiment of a device which may be utilized
for swaging the sleeve around the threads of the anchor bolt.
[0027] FIG. 9 shows the device of FIG. 8, showing how it is placed
around an anchor bolt.
[0028] FIG. 10 shows a perspective side view of an embodiment of
another swaging device which may utilized for swaging the sleeve
around the threads of the anchor bolt.
[0029] FIG. 11 shows a perspective front view of the swaging device
of FIG. 10.
[0030] FIG. 12 shows a front view of the swaging device of FIG.
10.
[0031] FIG. 13 shows a side vide of the swaging device of FIG.
10.
[0032] FIG. 14 shows a cross section of a portion of the
foundation, grout trough, template member and template member
suspension means, prior to placement of the grout.
[0033] FIG. 15 shows a cross section of a portion of the
foundation, grout trough, grout, template member and template
member suspension means, following the placement of the grout.
[0034] FIG. 16 shows a cross section of a portion of the
foundation, grout trough, grout, template member and template
member suspension means, following the placement of the grout.
[0035] FIG. 17 shows a cross sectional view of an anchor bolt, a
crimped sleeve, a suspension means and a portion of the template
member.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Prior Art Bolt Protection Devices
[0036] FIG. 1 generally depicts the base 10 of a wind turbine set
upon a foundation 12. Base 10 comprises a flange 14, by which the
base is attached to foundation 12 with anchor bolts 16. As shown in
FIG. 1, the anchor bolts 16 may be placed in side-by-side pairs,
the pairs extending radially from the center of the foundation 12
forming an inner ring of bolts and an outer ring of bolts. The bolt
pattern is, of course, determined by the bolt pattern on the
mounting flange 14. Each anchor bolt 16 has a corresponding nut 18
which is used to secure the base 10, and to apply tension to the
bolt. The exposed portion of each bolt 16 is usually protected with
a bolt cap 19.
[0037] A large number of anchor bolts 16 is typically used for this
type of foundation. For example, Henderson discloses an embodiment
having forty-eight tensioning bolts in the inner ring and
forty-eight tensioning bolts in the outer ring for a total of
ninety-six. In Henderson's foundation, the lower ends of the bolts
are anchored at the bottom of the foundation to a lower anchor ring
which may be constructed of several circumferentially butted and
joined sections. Although it is to be appreciated that other means
may be employed for anchoring the bolts, including drilling a
portion of the anchor bolt into the ground.
[0038] FIG. 2 depicts a bolt assembly 20 comprising a plurality of
anchor bolts 16 being lifted in preparation for being placed within
a relatively deep excavation prepared for construction of the
foundation 12. The anchor bolts 16 typically used for wind turbines
are approximately thirty feet in length, and usually have outside
diameters of 11/4 inch or 13/8 inch. Each anchor bolt 16 is
partially enclosed within a "hollow tube" or sleeve 22. The sleeve
is typically an elongated plastic tube fabricated from polyvinyl
chloride ("PVC") which encases the bolt 16 substantially through
the entire vertical extent of the concrete and allows the bolt to
be tensioned after the concrete has hardened and cured, thereby
post-tensioning the entire concrete foundation. The anchor bolts 16
comprising bolt assembly 20 are secured at the end by circular
template 23, which is attached to a lifting assembly 24 and lifted
by crane 26.
[0039] FIG. 3 shows a close view of a portion of the grout trough
28 before grout has been poured or base flange 14 has been placed.
Grout trough 28 is formed as follows: when the concrete is poured,
circular template 23, which remains attached to lifting assembly 24
and held in place by crane 26, holds the bolt assembly 20 in place.
Concrete is poured up around circular template 23, thereby forming
an inner ring groove in the top of the foundation 12 known as the
grout trough 28. Before grout 30 is placed in grout trough 28, a
sealing member 32 comprising foam, plastic or other material, is
placed around each bolt 16. Sealing member 32 is typically
cylindrical in shape, having a circular opening and longitudinal
slit cut through from the outside edge to the circular opening so
the sealing member may be placed around each bolt 16. The sealing
member 32 often has duct tape wrapped around it to secure it to the
bolt 16. Also shown in FIG. 3 is a leveling block 5 which is used,
in combination with a number of other leveling blocks contained
within the grout trough, to properly level the base flange 14. It
is to be appreciated that the placement of leveling block 5
immediately adjacent to sealing members 32, which is not an
uncommon occurrence in the prior art installations, inhibits the
uniform deformation of the sealing members as the base flange 14 is
lowered into the grout trough 28, resulting in the non-uniform
deformation discussed below.
[0040] FIG. 4 depicts a portion of a prior art foundation 12 after
the grout has been poured and cured, but before flange 14 has been
set upon the foundation 12 and nuts 18 made up onto bolts 16. As
shown in FIG. 5, flange 14 will be set on top of the grout 30
contained within grout trough 28.
[0041] FIG. 5 shows a cross section of a portion of the base flange
14, grout layer 30, and sleeve 22 of a prior art anchor bolt
installation for a wind turbine, where sleeve 22 contains bolt 16.
As shown in FIG. 5, the top of sleeve 22 is generally flush with
the bottom 34 of grout trough 28. It is to be appreciated that
before grout 30 is placed within grout trough 28, the top of sleeve
22 is exposed to whatever liquids may enter the grout trough, such
as water which may be placed in the grout trough to provide for
hydration of the grout. An annulus 36 is formed between bolt 16 and
sleeve 22, which provides a potential path for water or other
liquids, such as low viscosity grout, to travel along the length of
bolt 16.
[0042] As can be seen in FIG. 5, sealing member 32 is substantially
deformed once engaged by base flange 14. It is to be appreciated
that FIG. 4 shows an idealized view of the deformed sealing member
32, in which the deformation has been uniform. In actuality, it is
expected that the deformation will not be uniform because of, for
example, obstructions which may inhibit uniform deformation such as
the leveling block 5 shown in FIG. 3. It is also to be appreciated
that the deformed sealing member 32 displaces more volume than the
non-deformed sealing member. Because each bolt requires the sealing
member, a typical installation may have ninety-six of the deformed
sealing members 32 in the grout trough 28, thereby reducing the
overall volume of grout which may be placed, resulting in a final
grout pack with less strength than one having less grout
displacement. It is also to be appreciated that once the grout 30
sufficiently cures, tension will be applied to each anchor bolt 16
by the tightening of a nut at the top of base flange 14, causing
the bolt to move relative to the grout. Ideally sealing member 32
would remain stationary, allowing bolt 16 to slide through the
sealing member 32. However, deformation of sealing member 32
reduces the ease with which anchor bolt 16 will slide through the
sealing member 32, potentially causing sealing member 32 to also
move, potentially damaging the surrounding grout 30.
Embodiments of the Present Invention
[0043] FIG. 6 shows a cross section of a portion of the base flange
14, grout 30', and sleeve 38 of an embodiment of the present
invention. In contrast to the prior art shown in FIG. 4, it can be
seen in FIG. 5 that the crimped sleeve 38 does not terminate at the
bottom 34 of the grout trough 28, but rather extends upwardly
through the space in which grout 30' will be placed and partially
penetrates the bolt hole 13 of base flange 14. This feature
prevents the top of crimped sleeve 38 from being exposed to the
liquids which may be placed within grout trough 28. The use of
crimped sleeve 38 as the protective sleeve for bolt 16' is a
substantial departure from the present use of PVC sleeve 22.
[0044] The critical distinction between the presently disclosed
crimped sleeves from the prior art sleeves 22 is that the wall
thickness of the crimped sleeve 38 is substantially reduced, and
the tolerance between the internal diameter of the crimped sleeve
38 and the outer diameter of the bolt threads is substantially
reduced, resulting in an external diameter of the crimped sleeve
which is smaller than possible with the thicker-walled PVC sleeves,
allowing the crimped sleeves to extend into the bolt holes 13 of
the base flange 14. For example, a crimped sleeve 38 comprising
polypropylene sleeves has a closer tolerance than the available
PVC, such that the crimped sleeves 38 may have a clearance of 20
thousands of an inch between the internal diameter of the crimped
sleeve 38 and the outer diameter of the anchor bolt threads. As
shown in FIG. 6, this smaller outside diameter of the crimped
sleeve 38 allows a portion of the sleeve to be disposed within the
holes 13 in the base flange 14 rather than terminating at the
bottom 34 of the grout trough 28 as shown in FIG. 5 for the prior
art sleeves. The PVC tubes presently in use as sleeves do not
extend into the base flange 14 of the wind turbine. The diameters
of bolt holes 13 for the base flanges 14 for wind turbines are
approximately 11/2 inch, and the external diameters of commonly
available PVC tubes which may be utilized as hollow tubes for 11/4
inch to 13/8 inch bolts are too large to be inserted within the
holes of the flange.
[0045] As shown in FIG. 6, and in greater detail in FIG. 7, the top
of the crimped sleeve 38 is "swaged" such that a portion of the
sleeve conforms to the threads of the anchor bolt 16'. The swaging
serves several purposes. First, the swaging retains the crimped
sleeve 38 on the anchor bolt 16' such that nuts are not required to
retain the sleeve on the anchor bolt during transportation. This
characteristic allows the anchor bolts 16' to be shipped without
nuts, which reduces manpower required for placing the nuts on the
bolts for transportation and removing of the nuts from the bolts
upon arrival.
[0046] The swaging further inhibits the flow of liquids into the
annulus between the crimped sleeve 38 and the anchor bolt 16',
although it is to be appreciated that the exposure of the sleeve
end to liquid is reduced or eliminated, because of the capability
of placing the top of the crimped sleeve 38 within the base flange
14 rather than disposed at the bottom 34 of the grout trough 28. It
has been found that swaging approximately two inches of the top of
the crimped sleeve 38 forms a sufficient length of "crimps" 17
(i.e., portions of the crimped sleeve 38 which conform to the shape
of individual threads 21) to form an interference fit which
adequately inhibits liquid penetration into the sleeve-bolt
annulus. It has been found that crimped sleeves 38 comprising
polypropylene, or similar materials, have the desired mechanical
properties for swaging the sleeve material such that it conforms to
the shape of the threads. The mechanical properties of the
polypropylene are such that the material has a "memory" and retains
the crimps 17 once the swaging operation has been completed. It is
also to be appreciated that when the anchor bolts 16' are tensioned
by the tightening of the nuts 18, the mechanical properties of the
sleeve material are such that upon tensioning of the anchor bolt
16', the material will plastically deform and the crimps 17 will
relax and allow relative movement of the anchor bolt with little
resistance.
[0047] Also disclosed are swaging devices utilized in forming the
crimped sleeves 38. FIGS. 8 and 9 show a die assembly 40 which may
be utilized either with bolts 48 or with a hydraulic press to
create the crimping of the crimped sleeve 38. Die assembly 40
comprises two sides, wherein each side comprises a thread profile
46 which matches the thread profile of the anchor bolt 16'.
Compressing each side of the die assembly against a sleeve encased
anchor bolt causes the crimped sleeve 38 to conform to the thread
profile of the anchor bolt 16'.
[0048] FIGS. 10 through 13 show another embodiment of a swaging
tool 50. This tool 50 comprises a swaging end 56 and a threaded end
54, which define a longitudinal axis L, wherein the longitudinal
axis is at the center of the tool. The swaging tool 50 comprises an
opening coinciding with the longitudinal axis L, and the threaded
end comprises internal threads 52 which match the threads of the
anchor bolt 16'. The swaging end 56 comprises a plurality of
rollers 58a, 58b, 58c, 58d, 58e and 58f, each roller having the
same diameter. Rollers 58a, 58b, 58c, 58d, 58e and 58f are arranged
at different points along the length of the longitudinal axis L and
have different radial distances from the longitudinal axis. Rollers
58a through 58f are attached to the swaging end with fasteners 60,
such as bolts or screws.
[0049] The rollers 58a through 58f are disposed within the tool 50
to follow the threads 21 of an anchor bolt 16', compressing the
sleeve into the threads to create the crimps 17. The rollers are
disposed such that the center of each roller is a different radial
distance from the longitudinal axis L. It is to be appreciated that
a different swaging tool 50 may be fashioned for each bolt diameter
and thread type, including right-handed and left-handed
threads.
[0050] By way of example only, for a tool having an overall radius
of 2.0 inches, an inside diameter of 0.680 inches, and individual
roller diameters of 1.250 inches, the centers of the rollers may
have the following radial distances from the longitudinal axis
L:
[0051] roller 58a: 1.391 inches
[0052] roller 58b: 1.415 inches
[0053] roller 58c: 1.295 inches
[0054] roller 58d: 1.319 inches
[0055] roller 58e: 1.343 inches
[0056] roller 58f: 1.367 inches
[0057] Swaging tool 50, which may comprise suitable material such
as 1080 steel, is made up on at the end of a sleeve-encased anchor
bolt, with the swaging end 56 made up first. As swaging tool 50 is
screwed onto the threads, the bolt will ultimately engage internal
threads 52, which assist in guiding the tool. Once the swaging tool
reaches the polypropylene sleeve, roller 58f will be the first
roller to engage the sleeve, followed by 58e, etc., the rollers
compressing the sleeve into the threads 21. The swaging tool 50 may
be attached to both power tools and hand tools.
[0058] FIGS. 14 through 16 show the use of the template member 62.
In FIG. 14 the template member 62 is leveled above the grout trough
28, prior to the placement of the grout 30'. The grout 30' will be
added to the space defined by the template member 62 and the grout
trough 28 through fill holes 70. The template member 62 comprises a
surface which the grout 30' will contact but to which the grout 30'
will not adhere. The template member 62 may be comprised of an
upper metallic layer 64 and a lower layer 66, wherein the lower
layer 66 comprises a surface to which grout will not adhere. The
lower layer 66 contacts the grout 30'. The non-grout adhering
properties of the template member ensure that the grout will not
stick to the template and cause a rough grout surface.
Additionally, the propensity for the grout to "flash" or cure
unevenly may be reduced. The upper metallic layer 64 and lower
layer 66 may be bonded together through thermal, mechanical or
chemical bonding. The grout is added to the grout trough 28 through
fill holes 70 in the template member 62. The template member 62 is
held above the grout trough 28 through the use of suspension means
68. The suspension means 68 are used to retain the placement of the
template member 62 once the template member 62 has been leveled.
The suspension means 68 may be nuts that are made up onto the
anchor bolts 16' and are magnetically attached to the upper
metallic layer 64 of the template member 62. In FIGS. 15 and 16 the
grout 30' has been placed into the grout trough 28 of the
foundation 12 through a fill hole 70 that transverses the template
member 62.
[0059] FIG. 17 shows a cross sectional view of a portion of the
template member 62, an anchor bolt 16' and a rotating sleeve 72 as
the suspension means. The rotating sleeve 72 is made up onto the
anchor bolt 16' and suspends and supports the template member 62.
The upper layer 64 and the lower layer 66 are also shown. The
anchor bolt 16' extends downward through the foundation and upwards
through the template member 62, and will be used to retain and
support the wind turbine tower flange. The crimped sleeve protects
the anchor bolt 16' from corrosion caused by contact with water or
other electrolytes.
[0060] While the above is a description of various embodiments of
the present invention, further modifications may be employed
without departing from the spirit and scope of the present
invention. For example, the size, shape, and/or material of the
various components may be changed as desired. Thus the scope of the
invention should not be limited by the specific structures
disclosed.
* * * * *