A METHOD FOR PRODUCING A TUBE REINFORCED BY MEANS OF FIBRES

The invention relates to a method of continuous-working production of a tube reinforced by means of fibres, where as a spooling form of the reinforcement fibres most suitably a plastic tube is used, which is fed non-rotating through the spooling equipment, and by means of the spooling equipment onto the surface of said tube lengthwise and crosswise fibres are spooled.

Previously known is a spooling method of a continuous working production of tubes, among others from Finnish patent publication 105261, where by the production of a reinforced tube a support tube is needed which can be fed as a continuous tube to the equipment. There spooling equipment are around the support tube and also movable equipment enabling spooling of reinforcement fibres in the way wanted, as onto the tube surface. As fibres resin coated fibres are used which have to be preserved in a cold place, so that by conservation and spooling the resin remains solid on the fibre surface and does not adhere. When the fibre threads are fed from spools onto the tube surface the resin gets warm and adhering, hardens and binds the reinforcement fibres.

The disadvantage of the above presented solution is that resin covered fibre spools must be transported and preserved in a frost depot. Their original price also is more expensive with respect to customary bare thread. Furthermore, interruption of spooling may cause that already in the spooler the fibres adhere to each other, when the fibre spools get warm. Thus discharge of the fibres off the spool may become difficult.

In order to avoid above presented disadvantages and to enable the use of customary and bare, as to its price most profitable reinforcement fibre, a new manufacturing method is developed, which is characterized in that the treatment of the reinforcement fibres with binding agent, as resin, is done in connection with the spooling of the fibres outside the tube in placing around said tube a ring-like support tube as to its diameter greater than the diameter of the tube, and placing on the outer surface of said support tube, an apparatus sealed against said surface and comprising a ring chamber, whereby to said chamber the resin is fed in liquid form and the reinforcement fibres onto the tube surface are taken through said chamber, whereby they are in contact with the binding agent.

The remarkable advantage of the method according to the invention is that cheaper reinforcement bare fibre can be used, the conservation of which needs no special condition. By production of the tube, the spooling can be interrupted, as needed, and go on with it causing no problems in the feeding system of resin or in its hardening. The sealed ring chamber is easily placed around the tube and led to the binding agent in it.

In the following the invention is disclosed with reference to the enclosed drawing, where Figure 1 shows a side view of a spooling equipment. Figure 2 shows a side view of a dipping device of reinforcement fibres.

Figure 3 shows a side view of another dipping device of reinforcement fibres.

Figure 1 shows a diagrammatic side view of a continuous-working spooling equipment. As a blank tube used in tube production is a tube 1 moving from the left to the right in figure 1. The tube 1 is non-rotating. For tube 1 there is, for instance, in same space a production line, from where it directly becomes as spooling blanks to the spooling equipment. At first, on the surface of the tube 1 axial fibres 2' from fibre spools 2 are driven. In ring-shaped part 3 the fibres are led to tube 1 surface. In this part also the axial fibres are dipped and the control means (not shown) after part 3 steers the fibres onto the surface of tube 1. Further, going in tube 1 direction, the spooling equipment 7 of crosswise fibres 5" are placed, which contain reinforcement fibre spools 5. The crosswise spooling equipment 7 is rolled by adjustable speed together with their spools 5 around tube 1 and they can also be moved controllably in tube 1 direction in both directions. The crosswise spooling equipment 5 is controlled by means of computer 14, whereby their rolling and motion in the tube direction is adjusted in order to achieve different reinforcement layers. As reinforcement fibres resin-free bare fibres 2 ¹ and 5' are used by leading them onto the tube surface from spools 2' and 5 ¹ .

There can even be more crosswise and axial fibres or feeding devices in turns in tube 1 direction, when a thicker reinforcement layer is wanted. As devices for finishing treatment of the reinforced tube is, for instance, a tape device 9, cut off device 11 and pulling rolls 13 in order to pull the tube through the line.

The reinforcement fibres according to the invention are dipped with resin or similar binding agent not until they are being led onto the tube 1 surface. As such a dipping

means is the device presented above in figure 2 as part 3 of figure 1, which is a not- rolling apparatus 15 placed around tube 1 and comprising ring-like chamber 17. There is between tube 1 and apparatus 15 support tube 20, which stays put in regard to apparatus 15. Tube 1 glides inside ring-like parts, apparatus 15, support tube 20 and reinforcement fibres 2' and 5 ¹ get in contact with resin in the ring-like chamber 17. Apparatus 15 is furnished with sealings 16 so that the liquid resin stays in chamber 17 and, in order the chamber can even be some pressurized. To chambers 17 the resin is led by means of pumps 4 (figure 1) and the surplus resin can be removed through connections 6.

Figure 3 shows an apparatus suited for dipping of the crosswise fibres, which for its part has a rolling support tube 20, a rolling chamber apparatus 15, but a not-rolling ring-like resin feeding apparatus 19, which has a chamber space 18. From chamber space 18 there are several holes to chamber space 17 around part 15. The same support tube 20 can be used by production of tubes even of several sizes, since the fibres dipped in apparatus 15 are steered and turned, when support tube 20 has ended in tube 1 surface, and this distance can in the direction of the radius be tens of centimetres. For instance, as control means a stationary ring is used, the diameter of which is a little greater than the diameter of tube 1.

When by the dipping of reinforcement fibres, according to the invention, that takes place after spooling, the fibres get resin or similar on their surface, then most suitably a resin quality hardening by means of ultra-violet light is used. Figure 1 shows a device 8, which is a suited UV-hardener for a purpose like this. Also as dipping resins for fibres can even resins hardened in other ways be fed into the chamber, as by hardening by evaporation, chemical reaction, heat or freezing.

For dipping of the axial fibres most suitably an own dipping means is arranged (as per figure 2) and correspondingly own means for dipping of crosswise fibres 5 (as per figure 3). It depends on the quality of resin used, as binding agent, how it gets hard. Figure 1 shows how a hardening takes place by means of ultra-violet light in placing UV-source 8 after the spooling equipment 7. Hardening can be adjusted by means of the UV-light intensity. Hardening does not take place without ultra-violet light, so interruption of process and continuing anew is possible.

It is possible to connect the continuous production of blank tube 1 to equipment 1 and, for, instance, place the production of the blank tube and the spooling equipment according to the invention into the same moving vehicle or in the carriage it pulls, whereby the ready-made tube be directly let down to its site. This is made possible since the tube is not-rolling all he time during production.

Also placing the production line in a moving vehicle or carriage can be so made that the blank tubes are fed extended in a row to the spooling equipment, whereby only then the ready-made tube becomes continuous and as to its length unrestricted. The mutual joints of the blank plastic tubes can be made in some appropriate way, as by butt welding.