GB2104615A

GB2104615A - Coated felt pipe

Info

Publication number: GB2104615A
Application number: GB08216644A
Authority: GB
Inventors: Eric Wood
Original assignee: INSITUFORM
Current assignee: INSITUFORM
Priority date: 1981-07-21
Filing date: 1982-06-08
Publication date: 1983-03-09

Abstract

A method of coating a tube of felt material as it is discharged from a tubular felt manufacturing equipment, by means of a web of the coating material, which may be an extrudate or a tape of the coating material, laid onto the tube of felt in a direction transverse to the axis of the tube, whilst the tube rotates and feeds in an axial direction, so that the web will be laid on the outer surface of the tube in helically overlapped layers which are made to bond together, so as to form a seamless outer coating to the felt.

Description

SPECIFICATION Coating method This invention relates to a method for the coating of tubular felt material wherein an impermeable coating layer is applied to the outside of the tube of felt to define a smooth seamless layer.

The tubes produced in accordance with the invention specifically are adapted for use in a passageway or pipeline lining process in which the felt material forming the inner layer of the tube is impregnated with a curable synthetic resin whilst in fluent condition, and then the impregnated tube is everted into the pipeline or passageway by means of a liquid. The outer coating or membrane serves two functions, namely to enable the eversion of the tube into the pipeline or passageway, and also to keep the everting liquid out of contact with the wet resin. The everted tubular liner is held against the pipeline or passageway wall so as to be molded to the shape thereof, by means of fluid under pressure, and when the resin has cured, a rigid lining pipe of cured resin having the felt embedded therein, and a smooth inner surface formed by the membrane or coating, is defined.

The above described process is known, but the lining tubes for the process have been produced by folding a web of felt coated material into tubular form, and then by connecting the adjacent edges. This process is wasteful in materials, in that the web is usually cut from a larger web, and frequently the off-cuts must be discarded, which is wasteful both in terms of the felt material and the coating material, and also in terms of the effort to apply the coating material to the felt material of the off-cut.

The present invention aims at maximum utilisation of the materials, and in accordance with the present invention the method involves the coating of a tube of felt material as it is discharged from tubular felt manufacturing equipment, by means of a web of the coating material, which may be an extrudate or a tape of the coating material, laid onto the tube of felt in a direction transverse to the axis of the tube, whilst the tube rotates and feeds in an axial direction, so that the web will be laid on the outer surface of the tube in helically overlapped layers which are made to bond together, so as to form a seamless outer coating to the felt.

When the web is an extrudate, it may be applied to the rotating felt tube whilst soft so as to bond thereto and to the adjacent layers of the web, or a flame bonding technique may be used to soften the surface fibres of the felt and the surface of the web which is applied thereto prior to bringing same into contact. Alternatively, an adhesive could be used. Adhesive and/or flame bonding can be used whether or not the web is an extrudate fed directly onto the rotating felt tube, or whether it is in fact a preformed tape of the coating material fed from a reel.

The tubular felt may be produced by a machine which wraps one or more cardboard laps in helical fashion, and then needle punches through the overlapping layers, thereby firmly to bind the fibres together, and produce an integral felt tube without any longitudinal seam. The cardboard laps may be wrapped round a pair of spaced rollers, one or both of which is or are driven, and the spacing between which is variable, in order that the diameter of the felt material may be varied.

It will be understood that with the justability of the felt tube diameter, ensures that lining tubes for the process described above, of any size within the range of adjustment of the rollers can be produced, and that there will be no wastage of any felt material or coating material, as in the previous method of manufacture.

The thickness of the felt material can be made as desired depending upon the number of carded laps which are wound by the equipment, and the speed of axial feed of the produced felt tube.

Two embodiments of the invention are illustrated in the accompanying diagrammatic drawings, which are perspective views, and in the drawings:~ Fig. 1 is a view showing the use of an extruder for the application of a plastics material extrudate to the rotating felt tube; Fig. 2 is an end elevation of part of the equipment shown in Fig. 1; and Fig. 3 is a view similar to Fig. 1 but shows the application of a plastics material tape to the rotated felt tube.

Referring to Figs. 1 and 2 of the drawings, the equipment for producing the rotating and axially moving felt tube is known, and basically the equipment produces a tube by taking one or more carded laps L of fibres, and by winding them in overlapped helical fashion, and by needling through the helical overlaps for example by a needle bar N in order to produce a coherent integral felt tube T of thickness dictated by the number of carded laps, and by the speed of axial feed of the tube from the machine (indicated by arrow 10 in Figs. 1 and 1 B).

The tube T in fact is rotating as well as moving axially (as indicated by arrow 13), as the laps are fed over and driven by spaced cantilevered rollers 12 and 14 from the free ends of which the tubular material is discharged.

In accordance with this invention, the felt material tube T has a coating applied thereto before it is discharged from the ends of the cantilevered rollers 12 and 14, and in the arrangement shown in Fig. 1 , the coating material is provided by extruding the material of the coating from an adjacent extruder 1 6, in the form of a web 18. The web 1 8 is applied in a direction transverse to the axis of the tube and flame bonding equipment 20 serves to soften the face of the extrudate which is applied to the tube and also the surface fibres of the tube adjacent the extrudate or a previous coil of the extrudate. It is to be pointed out at this stage that the materials of the extrudate and felt should be compatible for the extrudate to bond to the felt. The extrudate bonds to the tube as it is coiled thereon.The extrudate, as will be appreciated, is wound helically on the tube by virtue of the tube's axial movement, and the helical coils overlap and are bonded together where they overlap by virtue of the flame bonding.

The result is that an integral seamless coating is formed on the felt leaving the bulk of the felt material able to accept resin in the wetting out process described above. The thickness of the coating is dictated by the size of the extrudate die, and also the speed of axial movement of the tube.

The equipment includes a chill roll C to chill and smooth the outer surface of the extrudate and a support roll S which supports the embodiments of cantilevered roll 1 4.

in the arrangement shown in Fig. 2, a tape 22 of the synthetic resinous coating material is fed from a reel, and an adhesive is applied thereto from an adhesive applicator 24 in order to adhere same to the felt material, and also to adjacent overlapped layers of the tape, in order to achieve the coating effect already described.

The advantage of the present invention is that the use of the felt material is maximised as is the use of the coating material, and there is no wastage. By virtue of feeding the felt tube over two cantilevered rollers, tubular laminates of any required size can be produced as the rollers 12 and 14 can be mounted so as to be movable together and apart as indicated by arrow 26 in Fig.

2. This adjustability may be achieved by mounting a roller 12 or roller 14 or both so as to be position adjustable.

Claims

1. A method of coating a tube of felt material as it is discharged from a tubular felt manufacturing equipment, by means of a web of the coating material, which may be an extrudate or a tape of the coating material, laid onto the tube of felt in a direction transverse to the axis of the tube, whilst the tube rotates and feeds in an axial direction, so that the web will be laid on the outer surface of the tube in helically overlapped layers which are made to bond together, so as to form a seamless outer coating to the felt.

2. A method according to claim 1, wherein the web is an extrudate, and it is applied to the rotating felt tube whilst soft so as to bond thereto, and to the adjacent layers of the web.

3. A method according to claim 2, wherein a flame bonding technique is used to soften the surface fibres of the felt and the surface of the web which is applied thereto prior to bringing same into contact.

4. A method according to claim 1, wherein an adhesive is used to bond the coating material to the felt.

5. A method according to any preceding claim wherein the tubular felt is produced by a machine which wraps one or more carded laps in helical fashion, and then needle punches through the overlapping layers, thereby firmly to bind the fibres together, and produce an integral felt tube without any longitudinal seam.

6. A method of coating a tubular felt material substantially as hereinbefore described, with reference to the accompanying drawings.

7. A tube of felt material coated according to the method of any preceding claim.