Pipes and tubular conduits – Flexible – Braided – interlaced – knitted or woven
Patent
1995-08-22
1998-03-31
Brinson, Patrick F.
Pipes and tubular conduits
Flexible
Braided, interlaced, knitted or woven
138124, 138125, 138137, 138109, F16L 1108
Patent
active
057327467
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to the technical field of pipes used for transporting gases, fluids, such as water, rainwater, or waste water, but also as a protective sheath, for various mains or conductors. It also relates more especially to pipes having a diameter lying between 30 and 1000 mm.
Currently, most pipes of this type are produced from east iron, steel, cement, or from very thick synthetic material, in order to have the desired strength. All these pipes have either the disadvantage of possessing a high weight per linear meter or, when they are made from polyvinyl chloride, of polluting the environment, since they contain chlorine.
Multilayer pipes are also known which, produced from composite materials, that is to say from materials of different type, have the disadvantage of requiring, in order to manufacture them, tools which are complicated, expensive and difficult to adjust.
This is the case with multilayer pipes described in GB-A-1,449,753, U.S. Pat. No. 3,977,440 and U.S. Pat. No. 4,044,799 which, being composed of an internal tubular ply, a strengthening reinforcement member having a lacunary structure or otherwise, and an external tubular ply, bond the reinforcement member to at least one of the plies by embedding it, by melting, in the external ply. The enhancement of the mechanical characteristics of the pipes thus obtained is largely counterbalanced by an increase in the weight of the pipe, increasing the amount of deflection when the pipe is laid between two supports. To these disadvantages, limiting the application of this manufacturing technique to pipes of diameters less than 100 mm, should be added those inherent in the manufacturing means which, requiring several stations and occasionally several injection heads, are expensive, complicated and tricky to adjust.
SUMMARY OF THE INVENTION
The object of the present invention is to overcome these disadvantages by providing an impermeable and strong multilayer pipe which has a low weight per linear meter and can be produced in nonpolluting materials which may or may not incorporate recovery products.
For this purpose, in the multilayer pipe according to the invention, the strengthening reinforcement member has, over the whole or part of its length, a lacunary structure which is reticulated, only the respectively internal and external faces of which are bonded to the adjacent plies and the lacunary spaces of which are blocked off, but not filled, by these plies.
This pipe offers the particular feature of possessing a central lacunary reinforcement member forming a brace between the adjacent plies and to which these plies are attached in order to form a perfectly impermeable, lightweight and strong tubular body.
According to the embodiments, the reinforcement member and its plies are produced in the same synthetic material or in synthetic materials of different types or colors, coming as virgin granules or mixed with recycling products.
In one embodiment, the reinforcement member made from synthetic material having a lacunary structure is locally replaced by a uniform layer of a substance which can be used to form a bellmouth for joining two lengths of pipe.
The invention also relates to the die for the manufacture of such a multilayer pipe.
For this purpose, this die comprises, going from the inside to the outside: composed of an axial core delimiting, with a sleeve surrounding it, an annular channel joined, upstream, to a material supply channel and running out, via its downstream end, toward a chilled sizing-die unit; lacunary-structure reinforcement member and composed of two sleeves surrounding the first extrusion assembly, and forming a second annular channel communicating, upstream, with a second material supply channel and, downstream, with an extrusion annulus, at least one of these sleeves including, at its downstream end, notches interacting with the annulus, this sleeve being connected to means capable of moving it in relation to the other sleeve in order to alter the cross-section of this annulus, co
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Courant Alain
Leroy Jean-Marie
Brinson Patrick F.
Etablissements Courant SA
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