FR2477062A1 - METHOD OF MANUFACTURING A FLEXIBLE TUBE WITH SEVERAL LAYERS WOUND HELICOIDALLY AND THE TUBE THUS OBTAINED - Google Patents

Abstract

THE INVENTION CONCERNS A PROCESS FOR MANUFACTURING A FLEXIBLE TUBE WITH MULTIPLE LAYERS HELICOIDALLY WOUND, AND THE TUBE THUS OBTAINED. THIS PROCESS CONSISTS OF HELICOIDALLY WINDING A BAND OF FLEXIBLE MATERIAL ON CHUCK 3 TO FORM A FIRST LAYER 5, WINDING HELICOIDALLY ON THIS LAST A METAL TAPE 8 TO CONSTITUTE A SECOND LAYER ON THE MANDREL 3 TO FORM A FIRST LAYER 5, IN WINDING HELICOIDALLY ON THIS LAST METAL BAND 8 TO CONSTITUTE A SECOND LAYER ON THE FLEXIBLE BAND-CI-CIIDALLY FORM A THIRD LAYER 10 AND TREAT THE ENTIRE TUBE SO AS TO BOND TOGETHER THE COILS TO COVER THE FIRST AND THIRD LAYERS 5, 10 IN AN APPROPRIATE TOOL 4. APPLICATION TO THE TRANSPORT OF FLUIDS, TO THE SHIELDING OF ELECTRIC CONDUCTORS DISSIPATED AND TO THE SHIELDED CONDUCTORS. ELECTROSTATIC CHARGES.

Description

The present invention relates to a flexible tube

and its manufacturing process.

  The invention relates especially to a flexible tube comprising at least one wall of flexible plastic material and preferably of polymerized organic material such as

  polytetrafluoroethylene, which is particularly suitable

  well to form tubes, because of its tenacity,

  its flexibility and resistance to chemical attack.

  In a known form of a flexible polytetrafluoroethylene tube, a polytetrafluoroethylene strip is wound helically so that the adjacent turns are glued together, for example by sintering.

to form the tube.

  However, such a flexible tube is entirely composed of

  polytetrafluoroethylene. In some applications, it is desirable that the flexible tube used be able to dissipate electrostatic charges from outside the tube or to shield conductors

electric it contains.

  The present invention relates to a tube

  flexible able to meet these conditions.

  According to one of these characteristics, this

  The invention relates to a method for manufacturing a flexible tube

  ble, characterized in that it consists in winding helicolda-

  on a mandrel in the form of overlapping turns a flexible material bonded in strip to form a first layer, to helically wound on the latter a metal strip to form a second layer, to wind helically on this second layer in the form of overlapping turns , a flexible material bonded in a strip to form a third layer, and to treat the multilayer tube thus made of

  to stick together the respective turns to cover

  first and third layers.

  In the flexible tube manufactured according to this method, the one-piece metal layer, which is conveniently interposed between the inner and outer layers of flexible material and thus protected by them, constitutes a conductor of electricity along the tube which can serve

  to dissipate charges or to form a shield.

  It is preferable that the flexible materials of the first and third layers are such that their respective overlapping turns can be glued together by applying heat and the treatment step of

  multi-layered tube for gluing the coils to cover

  Flexible material consists of passing the tube through a hot zone so as to stick the turns

  overlay, then allow the tube to cool.

  Preferably, the flexible material constituting the third layer is a polymerized or polymerizable organic substance, for example polytetrafluoroethylene: The flexible material constituting the first layer

  may also consist of a poly-

  mertered or polyherizable, for example polytetrafluoride

  ethylene and can be armed with fiberglass for example.

  The second layer can be rolled helicoldale-

  - on the first layer to form coils to

  cover and can be aluminum.

  Preferably, the multi-layer tube is

  corrugated so as to present one or more

  ribs and helical grooves, before the

  put in the treatment for gluing together the respective overlapping turns of the first and third layers.

  For example, a strip of aluminum may be

  helically wound on the mandrel so as to form overlapping turns before the winding of the first

  layer to form an inner support layer.

  This layer is intended to support the first layer until completion of the treatment of the tube intended to bond the overlapping turns of the first and third layers,

then she is removed.

  Also, it is possible to wind helicolda-

  another band material around the third

  layer to -mainten the latter during treatment.

  According to another characteristic of the invention, a flexible tube comprises a first inner layer, a second intermediate layer and a third outer layer, said tube being characterized in that the first and third layers consist of wound flexible strips of flexible material. helically and stuck together and that the second layer is in one

metal coiled helically.

  The first and third layers can be polytetrafluoroethylene and they can be equipped with

glass fibers.

  The second layer, which may be aluminum, is preferably continuous and completely separates the first and third layers. The second layer can

  be made of a spiral wound metal band

  and in this case the adjacent turns of the second layer may overlap or, alternatively, may

abut edge aboard.

  It is preferable that the tube is wavy

  dalement. The invention will be described in more detail with reference to the accompanying drawings by way of non-limiting example and in which: Figure 1 is a partial side view of the apparatus for the manufacture of the tube; Figure 2 is a large-scale section of a portion of the apparatus of Figure 1, which is intended to helically wave the tube; and FIG. 3 represents a partial section of the

  manufactured tube, which is mounted on a fitting.

  The flexible tube can be used for conveying

  carry fluids or contain electrical conductors and generally consists of inner and outer continuous layers of polytetrafluoroethylene and an intermediate metal layer which separates the inner and outer layers and which is for example both a shield and a continuous conductor to dissipate electric charges

trostatic in the tube.

  Referring to Figure 1, a strip 1 of aluminum foil from a coil 2 is wound on a fixed mandrel 3, the coil being supported by a rotating head (not shown) which rotates it around the mandrel axis 3. The wound aluminum strip 1 is pulled (without rotation) into a rotary ribbing and creasing tool (designated 4) at one speed

  such that the successive turns of the band overlap.

  The layer formed by the aluminum strip 1 is covered by

  green of a strip 5 of fiber fabric impregnated with polytetrafluoroethylene, which is wound on it in the same way from a coil 6 which is also

  supported by the rotating head, so that the turns

sives overlap.

  Another layer constituted by a strip 8 of aluminum foil is wound in the same way on

  the glass fiber layer impregnated with polytetrafluoride

  ethylene from a coil 7 which is also supported by the rotating head, so that the successive turns

overlap.

  Finally, a layer of a strip of polytetrafluoroethylene

  fluorethylene is wound around the aluminum layer 8 in a similar manner, from a coil 9 supported by the rotating head, so that the adjacent turns become

overlap too.

  To satisfy particular conditions, the degree of overlap of the respective adjacent turns of layers 1, 5, 8 and 10 can vary from about 5 to about

70% of the width of the bands.

  The rectilinear four-ply tube 12 thus formed is drawn into the tool 4 which, as seen in FIG. 2, comprises a rotating threaded die 14 having a first region 15 having a relatively coarse thread and a second region 16 having a finer thread, and a "taratfd" rotating 17 which is coaxial with the die 14 and the mandrel 3. The "tap" 17 has a thread whose pitch corresponds to that of the

  region 15 of the matrix 14. Said "tap" is rotated

  3.0 tion (by means not shown) so that its posi-

  tion remains fixed with respect to the matrix 14, its thread being aligned with the grooves delimited by the threads of the

region 15.

  The "tap" 17 and the region 15 of the matrix 14 are intended to helically wave the tube 12 and more particularly to give it ribs 18 and grooves 19 of helical shape. The ribbed tube passes next to the region 16 of the matrix 14 o, because of the smaller

  the net of this region, the ribs 18 are

  to reduce the width of the grooves 19. In this way, the tube is provided with helical ribs and grooves of a step much smaller than that of the

  strips constituting the layers wound helically.

  The helicoidally corrugated tube, which is generally designated 22, then passes through a tube 20

  refractory material in an oven 21.

  The temperature and the heating time are adjusted so that the overlapping turns of the respective layers 5 and 10 of polytetrafluoroethylene are glued.

  together by sintering or melting to form a waterproof tube

  mable and continuous wall. After cooling the tube 22, it is cut into sections as needed. The layer 1 constituted by the aluminum foil strip is then removed, for example by deforming the tube 22 to detach the aluminum layer 1 which can then be

  easily extracted from the bore of the tube 22.

  The flexible tube thus formed and consisting of the layers 5, 8 and 10 can be washed and dried and be used as such, or subjected to other manufacturing operations, such as cladding by means of a braided wire to provide adequate mechanical protection. Apart from the protection of the polytetrafluoroethylene impregnated fiberglass cloth layer 5 as the tube passes through the corrugation tool 4, the inner aluminum layer 1 is designed to mechanically support the diaper 5 during heating. However, it has been found that the presence of this support layer is not always essential since the glass fibers of the layer 5 can confer sufficient inherent support on the layer to prevent it, for example, from to collapse inside the tube during the heat treatment and in this case, it is possible to eliminate in the process described above, the winding step

  helical of the aluminum layer 1 around the mandrel 3.

  Another metal strip, for example an aluminum foil, may be wound helicoldally in the form of overlapping turns around the polytetrafluoroethylene layer of the tube, using an additional coil supported in the rotating head, before the tube is pulled into the tool 4 and heat treated, to protect and support the layer during the ripple and heat operations, the layer being removed from the tube by tearing after heating. However, it has again been found that in some cases such a support layer is not essential. The flexible tube produced as described

  comprises inner and outer layers 5 of polytetrafluoroethylene

  fluorethylene and an intermediate layer 8 of aluminum which is continuous and completely separates the inner and outer layers of polytetrafluoroethylene. The aluminum layer 8 constitutes a conductor of electricity along the tube and serving for example to dissipate electrostatic charges and the like coming from the outside of the tube and to constitute a shield for

  electrical cables that can pass through the tube.

  Although the layer 8 described is constituted by turns covered with an aluminum strip, it is envisaged to helically wind the band around the mandrel 3 and on the layer 5 so that the edges of the

  successive turns stumble against each other.

  The presence of the fiberglass fabric in the inner layer of polytetrafluoroethylene improves

  considerably the mechanical strength of the flexible tube.

  However, it is possible to use a band which consists only of polytetrafluoroethylene, in the same way

  than the band 10, to constitute the inner layer 5.

  The thickness of the layers 5, 8 and 10 of the flexible tube is determined by the thickness of the respective strips of

  the fiberglass fabric impregnated with polytetrafluoroethylene

  aluminum, and polytetrafluoroethylene-used and by the degree of overlap of successive turns of these bands. Thus, the thickness of the various layers of

  flexible tube can be determined by choosing suitable-

  the thickness of the bands used. However, it is envisaged that more than one band will be used to

  layers 5, 8 and 10 by providing additional coils

  Tape webs supported by the rotating head or by distributing two or more tapes simultaneously from a single reel. For example, if the thickness of the polytetrafluoroethylene-impregnated glass fiber cloth layer is to be increased, it is possible to helically wound two strips of said fabric onto the aluminum layer 1 (if present). ), from the coil 6 or from two separate coils, these two strips being then welded during heating to form a single layer 5. Also, it is possible to use more than one strip of polytetrafluoroethylene to form the In other variants of the invention, it is envisaged to invert the materials constituting the strips and 10, so that the latter and the respective layers of the multilayer flexible tube thus produced respectively comprise polytetrafluoroethylene. and a fiberglass fabric impregnated with polytetrafluoroethylene or to make the two layers 5 and 10 as a fabric of

  glass fibers impregnated with polytetrafluoroethylene.

  We will now examine Figure 3 which represents

  Partly in section, a flexible tube manufactured according to the methods described above and mounted on a connection generally designated

  electrical contact with aluminum layer 8 of blin-

  of the tube. For this purpose, the outer layer 10 of the helically wound corrugated tube is removed from the end portion of the tube to expose the aluminum layer 8. Next, a cylindrical metal sleeve 31 having a helical groove 32 on its inner surface which defines a

  tapping having a corresponding pitch and width

  Those of the helicoidal rib 18 of the tube are screwed onto the tube, so that the threading cooperates with the helical corrugations of the tube until its last two or three ripples protrude.

out of the sleeve 31.

  An insert, generally cylindrical 33, which may be polytetrafluoroethylene or aluminum,

  and which has on its outer surface a helical rib

  dale 34 having a pitch corresponding substantially to that of throat 19 of the tube, is screwed into the opening of the latter and tightens the aluminum layer 8 of the tube against the cylindrical sleeve 31 to establish a good electrical contact between them . The insert 33 is screwed into the opening of the tube until an annular flange 35 formed at its end abuts against the end of the sleeve 31. In doing so, the last two or three corrugations of the tube are compressed by the flange 35 in an annular recess 36 delimited

  the sleeve 31 and the insert element 33. These turns comprise

  are intended to prohibit the extraction of

fitting 30.

  As shown in FIG. 3, the layer 10 of the flexible tube 22 is removed over a predetermined length

  from the end of the tube so that it ends

  slightly beyond the end of the insert

  33, but is still in the groove 32 of the sleeve 31.

  It is possible to tighten around the sleeve 31

  a cylindrical metal collar (not shown) comprising

  a protruding lug and fix the latter to one element at a time to support the connection and therefore the tube and to establish an electrical connection between the support member and the layer 8 of the tube. Alternatively, it is possible to weld a tab directly on the sleeve 31 and use it to fix the connector 30 to a support and

to ensure that it is grounded.

  Although the flexible tube and its method of manufacture have been described with reference to the use of polytetrafluoroethyl to form layers 5 to 10, it is possible to use other flexible materials and more particularly materials. organic polymerized or polymerizable. For example, the layer 10 of the flexible tube may be made of polyvinyl chloride and the layer 5 of fiberglass cloth impregnated with

polyvinyl chloride.

  Also, it is possible to use other metal bodies to form the layer 8 in addition to the aluminum and the layer 1, if present, can be in any material that provides additional support to the layer During the heat treatment and which can be easily removed from the tube later, in case such additional support is needed. It goes without saying that many modifications can be made to the process and tube described and

  shown without departing from the scope of the invention.

Claims (26)

  1. A method of manufacturing a flexible tube comprising a plurality of layers, characterized in that it consists in winding helicoldalement on a mandrel (3) in the form of overlapping turns, a flexible material bondable (5) strip to form a first   layer (5) to wind helically over these two last   a metal strip (8) for constituting a second layer (8) wound helically over this second layer in the form of overlapping turns, a collapsible flexible material (10) in a strip to form a third layer (10), and treating the multi-layered tube (5, 8, 10) thus formed so as to bond together the respective overlapping turns of the first and third layers (5) and (1C).   2. Method according to claim 1, characterized in that the overlapping turns of the first and third layers (5, 10) are made of a heat-sealable material and that the step of treating the multi-layer tube (5, 8, 10) for bonding together the respective overlapping turns of the first and third layers (5, 10) consists of passing the tube in a hot zone so as to weld the lap coils, leaving thereafter the tube cool down.   3. The process according to claim 1 or 2, wherein   in that the flexible material constituting the third   layer (10) is a polymerised or poly-organic   mérisable. 4. Method according to claim 3, characterized in that the third layer (10) consists of a polymerized or polymerizable organic material armed with glass fibers.   5. Method according to claim 3 or 4,   characterized in that the third layer (10) consists of polytetrafluoroethylene.   6. Process according to any one of the claims   1 to 5, characterized in that the flexible material of the first layer (5) is a polymerized organic material or polymerizable.   7. Method according to claim 6, characterized in that the first layer (5) comprises a polymerized or polymerizable organic material with glass fibers. 8. Method according to claim 6 or 7, characterized in that the polymerized or polymerizable organic material constituting the first layer (5) comprises polytetrafluoroethylene.   9. Process according to any one of the claims   characterized in that the metal strip (8) is wound helically on the first layer   (5) so that its turns overlap.   10. A method according to any of the claims   cations 1 to 8, characterized in that the metal strip (8) is wound helicoldalement on the first layer (5) so that the edges of the successive turns abut One against the other.   11. Process according to any one of the claims   previous arrangements, characterized in that the metal strip   (8) constituting the second layer is aluminum.   12. Process according to any one of the claims   previous arrangements, characterized in that it consists in helically damming the multi-layered tube (5, 8). 13. The method of claim 12, characterized in that the multilayer tube (5, 8, 10) is waved helicoldalement before its treatment for gluing the respective overlapping turns of the first and third layers (5, 10).   14. Process according to any one of the claims   characterized in that it consists in spirally winding on the mandrel (3) a strip material (1), before the winding of the first layer (5) on the latter to form a layer intended to support   the multilayered tube (5, 8, 10) during the treatment   of the latter, then remove the support layer (1).   15. A method according to any of the claims   cations, characterized in that it consists in helically winding a strip material around the third layer (10) of the multilayer tube (5, 8, 10) before the step of treating the latter to constitute   a support for the tube (5, 8, 10) during the processing step.   then remove the tape surrounding the third layer (10). Flexible tube consisting of a first inner layer, a second intermediate layer and a third outer layer, characterized in that the first and third layers (5, 10) are constituted by helically wound strips of a collapsible flexible material, the respective overlapping turns being glued together and in that the second layer (8) is constituted by a metal coiled helically.   Flexible tube according to claim 16, characterized in that the third layer (10) is in one polymerized organic material.   Flexible tube according to claim 17,   characterized in that the third layer (i0) is in poly-   tetrafluoroethylene. Flexible tube according to claim 17 or 18, characterized in that the third layer (10) contains glass fibers.   20. Flexible tube according to any one of   16 to 19, characterized in that the first   layer (5) is made of a polymerized organic material.   21. Flexible tube according to claim 20, characterized in that the first layer (5) contains polytetrafluoroethylene. Flexible tube according to claim 20 or 21, characterized in that the first layer (5) contains glass fibers.   23. Flexible tube according to any one of   16 to 22, characterized in that the second   intermediate layer (8) is continuous and completely separates   the first and third layers (5, 10).   24. The flexible tube as claimed in claim 23, characterized in that the edges of the adjacent turns of the second wound coiled layer (8) abut One against the other.   25. Flexible tube according to claim 23, characterized in that the second layer (8) is wound   helicoidally so that its turns overlap.   26. Flexible tube according to any one of   Claims 16 to 25, characterized in that the tube is helically corrugated.