FR2673995A1 - Pipe with reinforced end pieces and method for manufacturing it - Google Patents

Abstract

Pipe (1) of the type including a barrel (2), at the ends of which are provided male (3) and female (4) end pieces, exhibiting coaxial peripheral surfaces between which a sealing gasket is interposed, when two male (3) and female (4) end pieces of two successive pipes (1) are fitted together, characterised in that at least one of the end pieces (3, 4) includes protective and reinforcing means (A) in the form of a cap (8, 9) forming an integral part of the said end piece (3, 4). Application to concrete pipes.

Description

 The present invention relates to a pipe, most advantageously made of concrete, with reinforced ends and its embodiment.

 The known pipes of this type comprise a generally straight barrel at the ends of which male and female ends are provided, obtained in one piece with the barrel during the same manufacturing operation. This can be carried out in several also known ways, with or without prestressing the concrete.

 The main techniques for manufacturing concrete pipes will be briefly recalled.

 A first known technique consists in producing the pipe by centrifugation, the concrete being introduced inside a mold of shape corresponding to that of the pipe, said mold being driven in rotation so that the concrete is pressed against the wall of the mold. under the effect of centrifugal force until a hollow pipe having the desired thickness is obtained.

 According to another known technique called laminocompaction, an external mold is still used but the concrete introduced into this mold is laminated against the internal wall of the mold - either by a shaft or by rollers - with a view to the gradual production of a pipe conforming to the internal shape of the mold.

 According to yet another known technique, a molding installation is used, most often vertical, essentially comprising an outer shell and an inner mandrel, providing a space in which the concrete is poured.

It can be armed or not. In the simplest embodiment, the concrete is poured and then it is waited for to set and then the pipe obtained is demolded. In a variant of this technique, a faster demolding is carried out and the pipe blank is extracted while the concrete has not yet definitively set. It suffices that the concrete then has sufficient cohesion to ensure the mechanical strength of the pipe. This variant is advantageous because it makes it possible to dispose of the molding installations more quickly, which are then freed up for another manufacture. In the simple molding technique or in the variant comprising rapid demoulding, it is conventional to compact the concrete by vibration.

 Those skilled in the art also know that the hardening of concrete can be accelerated by various known means, for example by raising the temperature (steaming).

 The summary indications given above are only illustrative of the techniques known industrially for the manufacture of concrete pipes.

 The pipes thus produced comprise male and female ends having opposite coaxial surfaces, between which a seal is interposed during the fitting of the male and female ends of two successive pipes.

 Practical experience shows that the ends are subject to shock, whether during handling and transport or the abutment operation of two successive pipes. Such shocks, which can be violent, deteriorate the ends by chipping, which can lead to the scrap of the pipe concerned. Production costs are therefore increased, not to mention the additional handling thus caused.

 In fact, it is sought to produce sets of pipes that meet increasingly stringent sealing criteria. Concrete pipes are indeed intended for the transport of the most diverse liquid products. When, for example, pipes intended for sanitation, for example for the operation of treatment plants, lifting stations, etc., it is important to obtain a perfect seal, not only at the level of the barrels of pipes but also of the assemblies between successive pipes.

If there is a shock at the ends of the pipes, the leaks are increased.

 In the past, attempts have been made, using auxiliary products of the resin or other type, to correct in the factory a defect which would be due to breakage or chipping of a butt due to an impact. It is quite clear that this remedy is only a palliative because this additional operation is expensive. Nor is it completely effective.

 It is also known that the industrial manufacture of pipes inevitably leads to dimensional variations due to manufacturing tolerances, so that the male and female ends do not have a perfectly reproducible and exact configuration. It is therefore desirable to improve the structure of the pipes to ensure uniform placement of the seals between the ends of two successive pipes. The manufacturing defects of the ends are particularly sensitive in the technique involving rapid demolding, which, as indicated above, is nevertheless desirable for the maximum productivity of the molding installation.

The purpose of the present invention is to remedy these various drawbacks, while providing new advantages and in particular:
- better resistance to handling shocks,
- a perfectly uniform and smooth surface of the butts,
- a reduction in the nesting effort between successive pipes, thanks to the quality of the geometry of the ends, and to their smooth surface,
- Improved sealing at the nesting of successive pipes, for the same reasons.

 To this end, it relates to a pipe of the type comprising a barrel at the ends of which there are provided male female ends having coaxial surfaces facing one another, between which a seal may be interposed during the fitting of two male and female ends of two successive pipes, characterized in that at least one of the ends includes protection and reinforcement means in the form of a cap forming an integral part of said end.

 Most advantageously, the pipe is made of concrete. The cap is preferably made of synthetic material, for example a polyester, reinforced or not, PVC, or another material compatible with concrete and its constituents (cement, aggregates, etc.); inert to aggressions from the ground (hydrolysis); behavior at temperature variations, compatible with that of concrete; resistant to aggressive fluids; sufficient resistance to baking (around 70 ° C).

 It will be noted that, according to an advantageous characteristic of the invention, the pipe equipped with the cap with one and / or the other of its ends has the same profile as a pipe which would be produced in a traditional manner in the same dimensions. and with the same geometry. Thus, the cap is an integral part of the ends, being anchored in the constituent material (most often concrete) of the pipe.

The subject of the invention is also a process for obtaining such a pipe comprising the following steps:
- projection of a polymerizable material on at least one removable end portion or headrest of a profile mold corresponding to one of the ends, prior to its insertion on either side of the mold of the barrel itself or shell,
- surface treatment of the polymerizable material, before it hardens, by projection of a granular material to constitute a rough anchoring coating of the cap to be obtained, capable of creating a surface for attaching said cap to the end piece to be molded later,
- polymerization of the material corresponding to the cap,
- insertion of the breastplates on either side of the mold shell, at least one of the breastplates being provided with a cap,
- simultaneous realization of the barrel and end caps of the conditions known in themselves,
- concrete hardening by known means,
- release of the hose fitted with at least one protective cap.

 According to a variant of the invention, the cap is extracted from the mold after the polymerization step, to constitute a storable prefabricated part, capable of being added later on at least one breast plate during a consecutive operation of molding a pipe.

 It will be noted that such an interruption of the abovementioned production process does not in any way change the course of this, which is repeated later where it was interrupted.

Thus, this variant does not imply that all the steps of the process are carried out in succession and without interruption one after the other, whereas in the process generally defined above, the pipe provided with its end (s) is manufactured in one time.

 Whatever the manufacturing method, a butt end cap according to the invention has not only the advantage of having been made waterproof and impact resistant during nesting, at the level of the coaxial surfaces facing the ends , likely to collide during this operation, but also to be protected during storage or handling on site, especially with regard to the male end, the most exposed.

 The cap thus produced also offers the advantage of constituting a real hoop by strapping the male end and thus improves its resistance to impact. This also contributes to avoiding the chipping, commonly encountered, of the end of the concrete pipes.

 In addition, the installation personnel, noting the presence of this cap, which may be of a different color from the concrete, is encouraged to be more vigilant. The cap also facilitates the fitting of the male end into the female end during assembly.

 In addition, as indicated above, the concrete pipes have manufacturing tolerances and are obtained according to methods which do not always make it possible to obtain faithful profiles, in particular at the butt ends, unless carrying out rigorous controls leading to a selection, resulting in a reject of certain defective pipes.

 The integration of a cap at this level also offers the advantage of reducing variations in the dimensions of the butt profiles by compensating for their appearance defects or differences in dimensions or shape.

 It is also known in advance that a cap according to the invention will constitute an end member of the pipe, without cracking and without bubble, contributing to good sealing of the assembly.

 According to another characteristic of the invention, means are provided so that the cap forms an integral part of the end piece and is made integral with the latter, so that the assembly is perfectly sealed and that it does not there is no infiltration of the liquid circulating in the pipe.

 The invention provides means for fixing the cap on the end piece, to make it an integral part of the latter, said means possibly being mechanical means in the form of anchoring elements of the cap, forming suitable baffles. to oppose the flow of water between the two materials, for example concrete-resin.

 The projection of a granular material on the polymerizable material constituting the cap, in a step of producing the latter, represents an advantageous solution for obtaining means for anchoring said cap, ensuring an effective barrier to the flow of liquids transported, by the very presence of the grains of the chosen material, representing as many obstacles to the infiltration of these liquids.

 According to a particular embodiment of the invention, the sprayed material, capable of ensuring adhesion of the cover to the concrete and their relative tightness, is a product in particles, for example sand, in particular of particle size 2/4.

 According to another particular embodiment of the invention, the polymerizable material projected to produce the cap has a thickness of between two and three millimeters approximately.

 According to yet another variant of the invention, after the stage of polymerization of the cap, pins of a length greater than the thickness of the cap are introduced into corresponding housings of the headpiece to ensure on the one hand the holding mechanical said cap on the latter during the molding operation of the pipe itself and during the subsequent nesting operation of the ends and on the other hand constitute front stops when the pipes are joined together during assembly.

 According to another possible characteristic of the invention, prior to the projection of the polymerizable material to form the cap, a lubricating film is applied to the teat, on the one hand to promote release from the mold and on the other hand to form a slippery body when joining pipes.

 In addition, such a deposit during molding makes the surface of the cap, corresponding to its external surface when it is in place on the end piece, sufficiently slippery to partially or completely eliminate the "soap" commonly used on construction sites. favor the installation of the pipes during their fitting at the time of laying.

 According to another characteristic of the invention, the internal waterproofing of the barrel is obtained in a known manner by using resinous concrete.

 As a variant, the internal waterproofing of the barrel is obtained by applying an epoxy paint or by fitting a sheath made of polyvinyl chloride.

 All these characteristics must be considered in isolation or according to all their possible technical combinations.

The invention will be further illustrated without being in any way limited, by the description which follows, given with reference to the appended drawings in which:
Figure 1 is a longitudinal sectional view of a pipe according to the invention.

 Figures 2 to 5 are sectional views illustrating the successive stages of a method of producing a cap on a male headpiece for obtaining a pipe according to the invention.

 FIG. 6 is a sectional view of a mold fitted with male and female face pieces fitted with caps according to the invention for the molding of a pipe according to FIG. 1.

 Figures 7 and 8 are respectively sectional views, on an enlarged scale, of heads for obtaining a male butt and a female butt during molding of the concrete pipe according to the invention.

 Figure 9 is a sectional view of a male butt in the process of fitting into a female butt.

 As shown in Figure 1, the pipe designated by the general reference I is constituted in known manner by a substantially straight barrel 2 at the ends of which are formed male 3 and female 4 ends obtained by molding concrete during the same operation , with barrel 2.

 This molding can be carried out by any known means as indicated briefly at the beginning of this description. Concrete can also be reinforced or unreinforced.

 The methods of molding the pipes themselves are indeed well known and will not be described further.

The present description will essentially relate to the means of protection of the ends 3, 4 which are the subject of the invention and to their method of obtaining.

 The male 3 and female 4 ends of the pipe 1 have respectively external and internal coaxial surfaces intended to cooperate, during interlocking, by means of a seal 5 (Figure 9). This seal 5 is previously disposed on one of the ends 3, 4 and is compressed between their cooperating surfaces during assembly, to create a packing pressure between them.

 The engagement of the male end 3 relative to the female end 4 takes place until a radial end plane 6 of the male end 3 comes into contact with an internal transverse shoulder 7 delimiting , with the internal coaxial surface of the female end 4, a housing corresponding substantially, apart from play, to the end part of the male end 3.

 According to the example chosen to illustrate the invention, the male end 3 and female end 4 comprise protection and reinforcement means in the form of a cap respectively 8 and 9 made of a material different from concrete. Each cap is an integral part of the end piece 3 or 4 by means of anchoring thereon, as will be illustrated in the description below.

The preferred embodiment of the pipe 1 according to the present invention is shown diagrammatically in
Figures 2 to 6.

 A removable end portion II of a mold 10, often called a breast piece 11, is used. There will now be mentioned by way of illustration a breast piece 11 corresponding to the male end 3 and a head end 12 corresponding to the female end 4.

 Figure 2 shows an example of a male head section 11.

 Figure 3 shows an alternative embodiment involving the film intended to facilitate the subsequent release of the cap.

 Figure 4 illustrates the application of a resin layer A intended to produce the cap according to the invention. In an advantageous embodiment, this resin A is applied by spraying.

 The polymerizable material A used must have the following properties: be compatible with concrete and its constituents (cement, aggregates, etc.); be inert to aggressions from the ground (hydrolysis); have a behavior at temperature variations compatible with that of concrete; resist aggressive fluids; have a sufficient resistance to baking (around 70 C).

 At present, the best results have been obtained with polyester resins, which may or may not be reinforced with glass fibers. PVC can also be used.

 Depending on the case, the deposit of polymerizable material A by projection has a thickness of the order of 2 to 3 mm.

 Thus the material of the cap A can take an absolutely identical profile to the breastplate ll serving it in a way as a mold.

 FIG. 5 illustrates a subsequent complementary step of the process, namely the projection onto the surface of the material, before it hardens, of a granular material B, to form a rough anchoring coating for the cap 8, 9 to be obtained, able to create an attachment surface for said cap on the end piece to be molded subsequently. It is for example a sand with a particle size 2/4. The resin A is then polymerized or hardened to obtain the cap 8.

 At this stage the production can be interrupted and the cap 8 thus obtained can be extracted.

It then constitutes a storable prefabricated part, which can be reintegrated later in the cycle for manufacturing the pipe 1. The cap (8, 9) is then replaced on its corresponding head for resumption of the manufacturing process.

Of course the cap 8, 9 could also be obtained, in a real separate mold, without changing the manufacturing process, which continues in the usual way as described below
The heads 11, 12 are arranged on either side of the mold part 10 corresponding to the barrel 2 itself or shell - said heads 11, 12 being respectively provided with a cap 8, 9, in place on themselves or reported as stated above.

 The barrel 2 and the ends 3, 4 of the pipe 1 are then manufactured in one piece by any known molding means, as mentioned at the beginning of the description.

 The rough coating B then ensures the attachment of the cap 8, 9 in the concrete part corresponding to the ends, so that the cap is an integral part and becomes integral with its respective end.

 The concrete is then hardened by any known technique, for example by increasing the temperature up to approximately 70 ° C., this operation then being carried out by steaming the pipe 1.

 During the steaming process, the plastic material constituting the cap may finish hardening, if the manufacturing process is carried out without interruption. The holding of the cap on the end is then perfect. It is then possible to demold the pipe l fitted with a protective cap 8, 9, which is integral with the pipes.

 According to an alternative embodiment, following the aforementioned polymerization step of the cap 8, 9, pins 13, 14 two or three in number, of a length greater than the thickness of said cap 8, 9 are introduced. in housings respectively 15, 16 corresponding to the heads 11, 12, on the one hand to ensure the mechanical strength of the caps 8, 9 on the latter during the operation of molding the pipe l proper, and on the other hand to constitute frontal stops during the joining of two successive pipes 1. During the hardening of the concrete, obtained by increasing the temperature as mentioned above, the pins 13, 14 decrease in volume under the effect of heat and thereby allow the cap 8, 9 to be demolded without difficulty. .

 Also according to an alternative embodiment, it is possible, as already indicated, to apply before the spraying of the polymerizable material A, on the breastplate 11, 12, a lubricating film, for example, and this to promote release from the mold.

 As shown in Figures 1 and 9, the inner wall of the barrel 2 itself can still be waterproofed using a waterproof coating 17 applied or attached in a known manner, as an extension, without discontinuity, of the cap 8, 9 .

 This waterproofing of the drum 2 can also be obtained by using resinous concrete, but it will often be preferred to apply an epoxy paint or even the fitting of a sheath made of polyvinyl chloride.

 Such an arrangement makes it possible to obtain continuity in the isolation of concrete from the fluids transported, which can have aggressive characteristics and combines the amorphous state of "PVC" for aggressiveness on the one hand, and reinforced concrete for its resistance to ovalization on the other hand.

 The invention is not limited to the embodiments described above by way of examples. The Figures illustrate the mounting of a cap at each end, male or female of a pipe. The invention is also applicable to the mounting of a cap on a single butt, preferably male. We also illustrated the anchoring method which seems the most interesting between the cap and the corresponding end piece, which involves a "sanding" operation. Any other means could however be used as soon as the cap is made firmly attached to the end considered. Similarly, if the invention is most advantageously usable with concrete pipes, it is not limited to this type of material. The mounting of a composite cap at one or two ends of the pipe, to improve the interlocking of two successive pipe sections, can also be provided for categories of pipes other than concrete.

 The reference signs inserted after the technical characteristics mentioned in the claims, have the sole purpose of facilitating the understanding of the latter, and in no way limit their scope.

Claims (12)

 1. Pipe (1) of the type comprising a barrel (2) at the ends of which are provided male (3) and female (4) ends having coaxial facing surfaces between which a seal is interposed ( 5), during the interlocking of two male (3) and female (4) ends of two successive pipes (1), characterized in that at least one of the ends (3, 4) comprises protection means and reinforcement (A) in the form of a cap (8, 9) forming an integral part of said butt (3, 4).  2. Pipe according to claim 1, characterized in that it is made of concrete.  3. Pipe according to one of claims 1 or 2, characterized in that the cap (8, 9) is made of synthetic material.  4. Pipe according to claim 3, characterized in that the synthetic material constituting the cap is a polyester, reinforced or not, PVC, or another material compatible with concrete and its constituents (cement, aggregates, etc .... ); inert to aggressions from the ground (hydrolysis); behavior at temperature variations, compatible with that of concrete; resistant to aggressive fluids; sufficient resistance to baking (around 70 ° C).  5. Pipe according to any one of claims l to 4, characterized in that it comprises a cap on a male or female end piece.  6. Method for obtaining a pipe according to any one of claims 1 to 5 comprising the following steps:  - projection of a polymerizable material (A) onto at least one end portion or headrest (11, 12) of a mold (10), of profile corresponding to one of the ends (3, 4), prior to its insertion on either side of the mold (10) of the barrel (2) proper or shell,  - surface treatment of the polymerizable material (A), before its hardening by projection of a granular material (B) to constitute a rough anchoring coating of the cap (8, 9) to be obtained, capable of creating a surface of hooking said cap on the end piece (3, 4) to be molded subsequently,  - polymerization of the material corresponding to the cap (8, 9);  - insertion of the face pieces (II, 12) on either side of the mold shell (10), at least one of the face pieces (11, 12) being provided with a cap (8, 9) forming an integral part pipe,  - simultaneous production of the barrel (2) and end plugs (3, 4) under conditions known in themselves,  - concrete hardening by any known means.  - release of the hose (1) fitted with at least one protective cap (8, 9).  7. Method according to claim 6, characterized in that the cap (8, 9) is extracted from the mold (10) after the polymerization phase to constitute a storable prefabricated part, subsequently added at least on a breast plate (11, 12) during a subsequent operation of molding a pipe (1).  8. Method according to one of claims 6 or 7, characterized in that after the polymerization step of the cap (8, 9), pins (13, 14) of a length greater than the thickness of the cap are introduced into corresponding housings (15, 16) of the headpiece (11, 12) to on the one hand ensure the mechanical strength of said cap on the latter during the operation of molding the pipe (1) proper and d 'on the other hand constitute front stops when joining the pipes (4) during assembly.  9. Method according to any one of claims 6 or 8, characterized in that, prior to the projection of the polymerizable material (A) to form the cap (8, 9), a lubricating film (C) is applied to the head (11, 12), on the one hand to promote demolding and on the other hand to constitute a slippery body during the joining of the pipes (1).  10. Method according to any one of claims 6 to 9, characterized in that the polymerizable material (A) sprayed to produce the cap (8, 9) has a thickness of between two and three millimeters approximately.  11. Method according to any one of claims 6 to 10, characterized in that the granular material (B) sprayed to constitute the rough material of the cap (8, 9) is a coarse sand, for example of particle size 2/4 , constituting both an anchoring means and an obstacle to the path of the liquid transported between the concrete of the end piece (3, 4) and the cover (8, 9) covering it.  12. As a means for implementing the method according to any one of claims 6 to ll and / or as an essential component of the pipe according to any one of claims l to 5, a protective cap for ends pipe, having the characteristics indicated in said claims.