CA1134290A - Manufacture of tubular laminates - Google Patents

Abstract

Manufacture of Tubular Laminates A tubular lining for lining passages is formed, such liner being constructed from a laminate comprising a resin absorbent layer and an impermeable skin. The laminate is wrapped to tubular form with the skin outermost and the free edges are butted together and are connected in this condition by a sewing operation. A sealing ribbon as applied over the sewing to seal the seam and stitching to prevent the flow of liquid or synthetic resin through the seam when the lining is used.

Description

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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 ~; , ., .

2 -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 ~34~

~ 3 -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 ~-- 4 -- ~
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.

~3~ 3 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 :
::

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 8 ~
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.

Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for the continuous production of tubular laminate of long length which is for lining a passageway or pipeline when impregnated with curable synthetic resin, wherein the tubular laminate is formed from a supply of a flat web laminate comprising a resin absorbent layer on one side of which is an impermeable layer, the method comprising the steps of feeding the web continuous-ly in the direction of its length and, whilst the web is in said continuous motion effecting the steps of (i) forming it to tubular configuration so that the impermeable layer-lies to the outside, and so that the free edge faces come in to butting relationship, (ii) sewing the said edges together whilst they remain in edge face to edge face butting relationship by means of stitching which extends across the seam, and (iii) applying a sealing ribbon or coating on the outside of the moving tubular laminate and over the stitching to prevent leakage of resin through the stitching holes when the tubular laminate is being installed.

2. A method according to claim 1, wherein a sealing ribbon is used and it is unrolled from a reel of such material, and is heated sealed to the outer skin of the laminate, over the stitching holes.

3. A method according to claim 2, wherein the ribbon is applied to said seam under pressure against a reaction roller or anvil plate.

4. A method according to claim 2 or 3, wherein the stitching is effected by reciprocating a needle through both of said free edges whilst they lie in butting relationship but define an inverted

Claim 4 continued....

V shape in section so that a straight needle penetrates each edge by being moved transversely of the V shape.

5. A tubular laminate produced by the method according to claim 1, 2 or 3.