Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to an anchorin~ structure
and to a method of producing one.
Such structures are particularly intended for use in,
, insulators such as pylon stays as described in the parent
application.
A difficulty occurs in the method of manufacture
' described in the parent application in relation to a wed~e
`, element which is moulded betwee~ an anchorin~ fittin~ in -~
the form of a sleeve and a rod received therein. The wedge `
element is ~ormed after the rod is received in the sleeve
by pourin~ a substance such as resin into the ~ap between
the rod and the sleeve and allowin~ the substance to set.
Under such circumstances it is dirficult to,check that the
wed~,e element is homo~,eneous and that it fills the Fap
' entirely without leavin~ any spaces or air bubbles. Such
. spaces reduce the mechanical stren~th and also reduces the
maximum voltage the anchorin~ structure can withstand. This ~ ,
;,~' is of importance in the hi~h tension applications envisa~ed.
The~present invention miti~ates thls drawback by
, 20 providin~ a method which simplifies verification Or the ~Jedge
;~ ' ' element. ''
' The present invention provides a method of producin~
,a rod anchoring structure comprisin~ the steps of ~ittin8
' the end oP 2 rod with a surroundin~ double-ended wed~e ,,
' element havin~ a neck from whi~h flared ends Of increasin~ '
'~ cross-sectional area extend in both axial directions alon~ '
~ the rod and of so fittin~ the wed~e element in an anchorin~
`' rittin~ that the wed~e element is radially compressed by the
¦ anchorin~ fitting even ~n the absence Or an axial load on ~-
3~ the rod.
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- Prefsrably the anchorin~ rittin~ ha~ ~n initial shape
o~ an open-ended tubular sleeve in which the wed~e-bearing
end Or the rod is received and which is subsequently de-
rormed into an open-ended nozzle-shaped sleeve pressin~
tightly aainst the wed~e element.
` Alternatively the anchorin~ fitting is formed by
,~, winding a ~ilament of suitable ~aterial such as metal wire
or resin-impre~nated or~anic fib're around the wed~e element.
~he wed~e element may have an axial pretensionin~
~0 applied thereto durin~ the fittin of the anchorin~ fittin~
The wedee element may be made, of resin which is ' ,~'
~, preferably moulded onto the end Or the rod in a mould for
~,1 ' producing the desired shape to avoid subsequent machining
r trimming. Advanta~eously the rod is made of resin
~ a~,glomerated ~ibres and the wed~e e;ement is moulded onto ~
'~, the rod be~ore the resin of the rod has completely poly- ~ -
.~ , .. - ~: .
'j merized, thereby improving adhesion between the rcd and '~
'i~ th~ wede element. `~;
~i ~he present invention aIso provides a rod anchorin~
'~ 20 8tructure produced by the method.
' , Embodiments of a rod anchorinE str~cture embodyin~
the present invention are described by way of example with
', reference to the accompanyin drawin~ in which~
j Figure 1 shows a rod with a wed~e element thereon;
,~ Figure 2 shows ~ sleeYeanchorin~ fitting receivin~ ~,
the wad~e element and before being pressed onto it; ;'~
~ ure 3 shows the fittin~ of figure 2 after bein~ 1
', pres~ed onto the wed~e element;
ure 4 shows a fittin~ analo~ous to the one of ;, ~'
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fi~ure 3, also comprising a hoop or strappin~ around the
; middle part o~ the sleeve, and
Fi~ure 5 shows a ~ittin~ analo~ous to the one o~
~i~ure 3, also comprisin~ a thin sleeve o~ soft ductile
metal between the wed~e element and the sleeve.
In ~igure l, a rod l made o~ res~n-a~lomerated ~lass
fibres is embedded at one end in a wedge element 2 o~ resin
~ which is full o~ an a~re~ate such as grains of silica
- an~or fibres and which has a double truncated~cone or
"diabolo" shape. The wede element 2 is moulded onto the
- end of the rod l in a two part mould (not shown). After
polymerization of the resin the mould is opened and ~he
rod 1 to~ether with its ~itted wed~e element 2 are removed,
which makes it easy to veri~y the condition Or the resin
o~ the wed~e element 2. To ensure a better connection
. between the rod l and the resin wedge element 2, it is
~, . . .
-r possible to start with an incomplete polymerization of
the resin of the rod l be~ore the mouldin~ of the wedge
element ~ thereto, and then allow the polymerization to
rinish after ~he ~oulding of the a~gre~ated resin.
An anchoring fitting is then applied to the wedge
element 2 in order to complete the anchorin~ of the end of
the rod l. The initial shape of this fitting is shown in
;i
figure 2. It comprises 2 cylindrical sleeve 4 which is open
at one end and closed at the other end by an end portion 3
, . :
, which includes an eye for fixin~ the rod to a support. The ~ ~ <
;j bo~e diameter of the sleeve 4 is sli~htly greater than the -
maximum diameters of the wedge element 2. The wedge element 2
`"''! ' ~S inserted into the slee~e 4 which is then deformed around
r.
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;~ the neck of the wed~e element 2 to become a tight rit. The
deformation may be by for~ine, by a cold working method
such as rollin~ or, when a relatively thin sleeve of ,
ductile metal such as aluminium is used, by isostatic
pressin~ inside 2 pressurized elastomeric casin~ or by
magnetic crimpine. The anchoring element shown in ~i~ure
is thus obtained,
If greater stren~th is required ~or the anchoring
~itting, the sleeve 4 may be made of steel (or any other
metal havin~ high mechanical stren~th) and should be pressed
aeainst the wed~e element 2 in the re~,ion of the neck and
~`~ then (or preferably simultaneously) on either side thereof.
The mechanical ætren~th of the anchoring ritting can
be ~urther reinforced by strappin~ the deformed sleeve `~
~igure 4j. The deformed sleeve can be strapped in the
usual way by windin~ a metal wire round it or even by
casting an exterior sleeve 5 made of an alloy havin~ a `~
moderate meltin~ po~nt~ such as an alumin;um alloy,
To be more certain of preYenting any inclusion of air
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between the wed~e element 2 and the bore of the sleeve 4
~ it is advanta~,eous to cover the preformed resin wed~e
- element 2 with a protective layer 5 made of a soft ductile
metal such as aluminium.
; One advantage of pressing the sleeve 4 onto the resin `
; wedge element 2 i9 that the progressive deformation of the
~;~ sleeve 4 on either side of the neck can be made to provoke
a condition of permanent tensile stress with its re~ultant
in the axial direction b~tween the wedge element 2 and the
~leeve 4. This stress contributes to pressin~ the two conical
.
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parts o~ the wed~e element 2 a~ainst the nozzle-shaped bore
of the sleeve 4. When the rod 1 is subsequently subjected
to lon~itudin~l traction, there is no displacement Or the
wedge element 2 in relation to the nozzle for as lon~ as
khere remain c~mpression stresses at the wed~e-nozzle
inter~ace on the side on which the traction is applied
(i.e. on the side which is pro~ressively releaved o~ stress ~;
by the applied traction). This effect can ~urther be
accentuated by subjecting the rod 1 and consequently the
resin wed~e element 2 to a traction during the ~orming of
the sleeve 4 about the wed~e element 2. For this purpose ~ .
~t is advantageous firstly to press the part or the sleeve
4 which is closest to the end o~ the rod 1, up to the neck
then to apply traction to the rod 1 rrom its opposite end
and then to continue the pressin~ o~ the sleeve 4 over the
other half Or the wedge element 2.
Althou~h the variants of embodiment of the improved
structure, as well as their manu~acturin~ methods, which
have just been described, appear pre~erable, it will be
. - . .
. 20 understood that various modifications can be made thereto
without ~oin~ beyond the scope of the invention, it being
possible to repla~e some elements or some operations by
... others w~ich would still fall within the scope of the claims.
In particular the anchorin~ fitting could be formed by
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` . winding a filament or thread of suitable material around the ~ ~
. wed~e element 2. The filament should be ti~htly bound to ~ -
provide the required compressive stress in the wedge.element.
. Suitable materials include metal wires or ropes and resin
: bounded fibres.......... , . ;~ :
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