Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Manufacture of Tubular Laminates
This invention relates to the manufacture of tubular
laminates comprising an inner layer of a resin absorb-
ent ma-terial, such as a fibrous felt and an outer skin
of synthetic plastics material.
These laminates, frequently re~erred to as "bags", are
for insertion in pipelines or passageWays to line same
with the resin absorbent layer, impregnaked with, so as
to be immersed in, a curable resin. When the bag lines
the pipeline, the ab orbént la~er is located closér to
the passageway surface than the said ~kin, and the
laminate is held in position by fluid under pressure
until th~ re~in has set su~ficiently hard tD form a
hard proteative resin plpej with the abso~bent materlal
lS ambedded therein, shaped to th~ pas~ayeway surfaoe, and
having a smooth inte~rnal surfacè deflned by ~he skin.
The n~rm~l method o~ ins~rting ~h~ at~ ls to e~t
lt into the~pass~geway or plp~l$ne f~ùm one ~nd ~her~o~
the eva~ion being ~eated ~ u~lng ~ ui~ to ~v~rt
the laminate and also buoyantly to support ~hQ laminate
as~;it travels into the passageway or pipeline thxough
the already everted portion thereof. This method is
used when~the laminate is~pre-impregnated with the resin
~`by injecting resin into the laminate or bag priox to
;;25 eversion thereof. Wven when the laminate is impregnated
during eversion~i.e. in the pipeline or passageway) the
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laminate, as it will s-till be of measurable weight, is
best supported by liquid so it is everted into the pipe-
line or passageway.
As will appear clear hereinafter however, the method of
inserting the bag is not part of the present invention,
nor is the material which is used to impregnate the abso-
rbent layer. The most common material for this purpose
is the resin described, but other materials such as
cementitious or bituminous materials can be used.
The present invention is in fact concerned with the manu-
facture of the laminate but it is important to apprecia-te
the end use of the laminate to understand the problems
which have been experienced therewith.
~he normal method of manufacture for the lam$nate is to
start with a laminate web comprising the absorbent layer
and skin and to overlap the edges to ~orm a tube, the
overlapping edges being joined by sealing strips or the
like.
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The problem which arises in connectlon with the use of
such laminates is that the overlapped portions de ine a
seam of substantially greater thickness than the
remalnder of the laminaté and when the la~inate 1~ everted
extra~stres~es are pl~ced upon the seam, 1.~ ~t thé
very loaa~i~n whexe d~sireabl~, hl~h ~kxa~s ~hould be
avoided, because the seam heretofo~e has be~n th~ weake t
part of~the laminate. Also, it has been a problem
effectively to seal the seams so that there will be no
leakage of the resin or liquid through the laminate.
As a result of manufacture the laminate in the manner
described, failures in the form of leakages and bursting
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of laminates at the seams during installation have
resulted.
The present invention aims at providing a method of
` manufacturing laminates as described whereby the afore~
said difficulty may be avoided.
Accordingly the invention provides that the tubular
laminate is produced by forming a web of the laminate
material into tubular form with the skin outermost and
the edges defining the seam butted together, connecting
said butted edges by sewing across the seam or through a
tape extending across the seam, and sealing the stitching
by applying a sealing ribbon or a sealing coating to define
a strip or strips over the stitching, which stxip or
strips is or are also to prevent leakage of resin or
liquid through the stitching holes when the laminate is
being installed.
When a sealing ribbon is used it is preferably unwound
from a roll of such material and is heat sealed to the
skin of the laminate, over the said stitchlng holes.
The manufacturin~ preferably is contlnuous and the skin
may be for example polyurethane or polyvin~lchloride, the
strip being a compatible heat sealable ma~riaL. ~hen
polyurethane ls used, it may be nea~ssary ~o include a
reinforcing screen in the rlbbon beeause when heak~ng
polyu~ethane i-t is easy to make it unhandable, PVC is
much ~ore stable over a wlde temperature r~n~P and
there~ore is preferred. The absorbent material may be a
polyurethane or polyester fibrous felt.
It is not usual to stitch together butted edges to make
a tube. Normally, sewing can only be effected by
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bringing the regions o~ the material adjacent the ed~es
face to Eace, ~ith the ed~es facing in the same direction,
the sweing heing effected through the overlapped regions.
When such a tubular laminate is opened out, there are two
excess edge strips which either ~ace outwards or inwards
depending upon whether the tubular structure is turned
inside out (as it would be in the case of portions of
items of apparal such as trouser legs or jacket sleeves
which have a sewn seam) or not.
There is also described herein a novel form of sewing
operation which has been speci~ically designed ~or
sewin~together butted edges of material and which works
very satisfactorily in connection with the manufacture of
tubular l~minates in accordance with the present
inventionO
An embodiment o~ this invention will now be described, by
way of example, with reference to the. accompanying drawings,
wherein:-
Figure 1 shows i~ section a piece of the laminated
material to be ~ormed into a tubular laminate in accordancewith the said embodiment o~ the invention;
Figure 2 ill~strates in perspecti~e view how the tubular
laminate is ~anu~act~x~ ln accordance wlEh the ~aid
embcdiment o~ the lnv~n~lon; ~nd
Figures:3 to 8 illustrate, in perspectiVe views,
respective stages in ~orming the stitch ~ormation holdln~
the butted edges o~ the tubular laminate shown in Figure
2, except for Figure 5 which is a sectional view taken on
line V-V of Figure 4.
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Referring to the drawings, in Fiyure l there is shown a
section of laminate material which is used ~or forming
the tubular laminate in accordance with the present
invention. The material in this example comprises a
~: 5 relatively thick layer 10 o the fibrous ~elt material
which serves as the layer for absorbing the resin in the
manner explained herein, and laminated to the felt is a
skin or membrance 12 of synthetics plastics material
which in use acts as a balloon whereby the laminate can
be shaped by fluid pressure to the pipeline or passageway
to be lined. The felt lO may be o~ polyurethane or
polyester fibrous material manufactured by conventional
needling processes, whilst the skin 12 may be a coating
of PVC or polyurethane applied in any suitable manner.
Figure 2 shows how the web of material o~ which a section
is shown in Figure l, if formed into the tubular laminate.
The web is fed from a roll with the skln side acing down-
wards~and the edges arè rolled over to meet a sewing
apparatus 40 which sews the edges together whilst they
are in face to face in butting contact in order that the
said edges will be held together and there is applied
subsequently and over the stitching 16 a ribbon 18
(which~may be a hot extruda~e~ o synthetlc plastics
material which is s~aled to the ou~er ~kin~ In this
~5 example a he~ting apparatus 20 so~tens tha strip material
before it is applled to the skin 1~, and indeed the
softened m~terlal can seal the nee~le holes ~ormed by
the stitching opera~ion 16.
The heating apparatus 20 is preferably a hot air blower
and is arranged to be deflected out of the impingement
position on the ribbon 18 in ~e event of movement of the
tubular laminate in the direction 22, ceasing. -The edges
of the laminate adjacent the seam may also be heated prior
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to the application of the ribbon 18. The operation when
started is continuous, and tubular laminates of the order
of 200 and 300 metres can be produced by the method. There
may be a pressure roller 24 or a flat anvil plate arranged
to press against the ribbon 18 in order that the soft
ribbon will be nipped or pressed to the skin 12 over the
butting edges of the laminate to form a sealing strip.
If the outer skin 12 is PVC and the ribbon 18 is also PVC
an extremely good seal is achieved between the skin and
ribbon and a very effective and strong seam of minimum
additional thickness as compared to the remainder of the
laminate, is achieved. ~he ribbon 18 can be of a yieldable
material, as the s~itching 16 will in fact take the strain
across the seam when the laminate is suhsequently used as
described herein. It i5 preerred that the strength of
the seam be taken by the sti~chin~ and the~e~or0 the strip
18 ls preferably ~f a yieldable material. A tubular
laminate produced in accoxdance with the method can be
everted extremely satisfactorily in the manner hereinbe~ore
described, even after the interior of the laminate has
been impregnated with a curable resin in ~hich the felt
layer 10 bec~mes soaked and embedd~d.
Re~erring to Figures 3 to 8, these ~igures show how the
stitching 16 is ~ormed, and referring firstly to Figure
3, it will b~ seen that the two edyes A and B of thè
laminate mat~rial to be sewn to~th~r a~0 a~rà~a in
b~tlng~cont~c~, but ~ ch ~ha~ ~h~y ~in~ ~n
lnverted V~shape in ~ection, the V angle helng .lndicate~
by numeral 30 in Fi~ure 3. ~y thls arXanCJement r a sinyle
straight needle 3~ reclprocating horizontall~ as indicated
by arrow 3~ can penetrate both edge A and B~ The needle
34 carries a strony yarn or twine 36, and it should be
borne in mind that the two edges A and ~3 during the
sewing operatior in fact move _ontinuously in the direction
of arrow 38.
Figure 4 shows the needle 32 a~er it has penetrated both
edges A and B and the end carrying the yarn 36 has
projected through edge B. It should be mentioned that
the needle 36 penetrates ~he skin 12 on edye A and
emerges rom the skin 12 on edge B. When the needle
head emerges, the loop of twine is engaged by a looper
40, thereby to retain a loop of twine which will form
a lock stitch, as described herein.
Referring briefly to Figure 5, this Fiyure shows how the
needle 32 penetrates through the space o~ the V-section
de~ined by the two edges A and B, and caxried across
this space are lengths o the twine 36 to assist in
holding the butted edges of the laminate together.
Referring now to Figure 6, this Figure shows the position
after the needle 32 has retracted ~rom thP Figure 4
position, and a loop L of the twine has been retained by
the looper 40, which has now moved across the butting
edges A and B a~ shown in Figure 6 and is presented to
the needle 32 which is ready to make a ~urther penetration
stroke similar to the stroke illustrated in Figure 4,
but by the time this stage has been rea~hed, th~ laminate
ha~ advancdd in the direction o~ ~rrow ~8j and thereore
the pre~ious holes ~ and 44 mad~ ln th~ edgas ~ and B
by the numeral 32 have advanced out o ~he path o
reelprocation of the needle.
Figure 7 shows a stage simllar to Figure 4 ln that the
needle 32 has again penetrated the edges A and B, but
this~time the needle 32 has passed through the loop L
which is there~ore locked in position and forms a
bridge across the butting edges A and B. Figure 7 also
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shows that the looper 40 has once more traversed the
butting edges, and has picked up the loop of twine in
the region of the eye o~ the needle. The procedure
repeats in that the needle 32 now retracts, and the
looper 40 carries a further loop L2 as shown in Fi~ure
8 across the seam and has presented the loop L2 once
more to the retracted needle 32, so that when the needle
32 again efects a penetration stroke, a further locking
stitch will be formed. The process o~ course repeats
cyclically to form a long sewn seam illustated by 16 in
Fi~ure 2, and great lengths of tubular laminate can be
produced by this method.
It will be seen that an e~fective stitching operation
results and ~he sewing thread ~s well as being interlocked
effectively bridges the ~utt ~ace seam botween the edges
A and B effectively holding same together prior to the
covering thereof by means of the sealing ribbon. The
resulting structure is extremely strong in the region of
the seam and the thickness of the structure in the region
of the seam is increased only minlmally. Laminates
constructed in aecordance with the inventlon can e~fect-
ively be everted as described herein.
In a modiied arrangement, instead of the stitching,
bridging the seam or stron~ tape i6 used and th~ tape is
~5 stitched at each side to the respectiv~ ~dges A and B,
at~r the sewing 1~ cover~d by a ribbo~ or xl~n~ simll~r
to ribbon 18.
The equipment or manufacturing the lamlnates described
is relatively simple and inexpensive.
