Pipe or the like, a female end ring, and a method of manufacturing such a pipe or the like

A pipe formed from a concrete cylinder has an end ring with a ferrule which can be snuggly mounted on one end of the pipe and a skirt axially adjacent to the ferrule for receiving a mail endpiece of another pipe. The ferrule is expanded as it is mounted on the cylinder and exerts a compressive force against the outer peripheral face of the cylinder for forming a secure seal. A rib may be disposed on an inner annular surface of the ferrule and an adhesive may be applied for enhancing the seal between the cylinder and the ferrule.

BACKGROUND OF THE INVENTION

The present invention relates to a pipe or the like, of the type comprising:a concrete cylinder possessing at least one annular end of determined longitudinal axis, defined in particular by a longitudinal outside peripheral face and by a transverse front face;a female end ring coaxial with said end and secured thereto, the ring consisting in:firstly a longitudinal ferrule for securing to the cylinder, the ferrule being defined in particular by a longitudinal inside peripheral face fitting snugly against said outside peripheral face in the immediate vicinity of said front face; andsecondly a longitudinal skirt projecting longitudinally over said front face to engage coaxially on a male endpiece of another pipe or the like.

The term “the like” as used herein with respect to pipes means building elements and ducts that can be assembled by being engaged mutually, such as galleries, access holes, so-called “ovoid” interfittable ducting, ducts of the type sold under the registered trademark “MODULOVALE”, and shelter modules, with these examples not being limiting in any way, providing said outside peripheral face presents a cross-section that is curved and convex, either in usual manner or else following simple adaptation in order to implement the present invention.

Similarly, the term “concrete” should be understood herein in its most general sense, covering in particular both concrete based on resin and concretes based on a mineral binder.

In the present state of the art, the female end ring made of metal or of synthetic material is usually fastened to the cylinder by overmolding the cylinder directly onto the ferrule. By way of example, such a technique is described for a female end ring of synthetic material in British patent application No. 2 217 418, which also mentions the possibility of fixing the ring on the cylinder after the cylinder has been made, probably by using a cement given the complexity of some of the shapes described.

The fastening obtained in that way between the female end ring and the cylinder can be satisfactory providing the precaution is taken of shaping the ferrule in such a manner as to obtain mutual anchoring via complementary shapes, however whatever precautions are taken in this respect, sealing between the ferrule and the cylinder remains problematic, even if sealing is defined merely as an absence of any visible seepage of a liquid placed at a pressure close to ambient pressure going from one side to the other of the gasket between the ferrule and the cylinder.

Proposals have also been made, in U.S. Pat. No. 5,180,196, and specifically with reference to FIG. 6 of that document, to make a female endpiece on a longitudinal concrete cylinder by longitudinally engaging a ferrule-forming zone of a longitudinal female end ring on an outside peripheral face at one annular end of the cylinder under conditions such that another zone of the ring forms a skirt projecting longitudinally from the front face of the cylinder for receiving internally a pipe of different design.

Sealing between the ferrule of the female end ring and the outside peripheral face at the end of the cylinder is then provided by two transverse annular bands that are tightened by screws, locally surrounding the ferrule and locally pressing against the outside peripheral face at the end of the cylinder, thus also providing mutual fastening by friction between the cylinder and the female end ring.

The use of such bands can limit the applications of the pipe or the like made in that way in that the material from which the bands are made, which material is dictated by considerations of a mechanical nature, can be incompatible with certain installation conditions for the pipe or the like. Thus, as a general rule, bands are made of steels of a grade that is selected as a function of criteria concerning traction strength and modulus of elasticity, but such seals are generally vulnerable to corrosion and are consequently unusable whenever the pipes or the like are to be buried (unless they are subjected to additional anti-corrosion protection and/or treatment which is expensive and of short-term effectiveness).

In addition, the effectiveness of the sealing and the fastening between the ferrule of the female end ring and the outside peripheral face at the end of the cylinder then depends on the magnitude of the transverse pressure between them, which in turn depends on the value of the transverse pressure applied by the annular bands to the outside of the ferrule, and consequently to a circumferential tension given to the annular bands by screw-tightening.

Unfortunately, the pressure applied by the bands to the ferrule gives rise to transverse thrust pressure from the ferrule of the female endpiece on the outside peripheral face at the end of the cylinder only through the ferrule, making it necessary to ensure that the ferrule tends to shrink onto the outside peripheral face of the end of the cylinder from a rest condition in which it is engaged on said outside peripheral face.

The ferrule has a natural tendency to oppose such shrinkage from its rest condition so obtaining mutual transverse thrust pressure between the ferrule of the female end ring and the outside peripheral face of the cylinder with sufficient magnitude to ensure effective sealing between them and also to ensure that they are effectively fastened together requires a considerable amount of pressure to be developed between the bands and the ferrule by putting the bands under circumferential tension at the risk of causing irremediable damage to the ferrule.

In practice, the desire to avoid any risk of such damage leads to the magnitude of the circumferential tension in the bands and of the pressure they apply to the ferrule being limited, and the tendency of the ferrule to oppose shrinkage means that the magnitude of the transverse thrust pressure actually applied by the ferrule to the outside peripheral face of the cylinder is even smaller, i.e. not only is fastening between them ineffective, but also the resulting sealing is doubtful.

SUMMARY OF THE INVENTION

The object of the present invention is to remedy that drawback and to this end, the present invention provides a pipe or the like of the type specified in the introduction, characterized in that the ferrule is in a state of circumferential elastic tension providing sealing relative to said outside peripheral face by said inside peripheral face applying thereagainst transverse pressure which is circumferentially distributed in continuous manner.

Between the cylinder and the ferrule of the ring, and regardless of whether the ferrule is made of metal or of synthetic material, this transverse pressure creates contact that is much more intimate than in the prior art, with this intimate contact considerably improving mutual sealing.

Depending on the respective shapes of the inside peripheral face of the ferrule and of the outside peripheral face of the cylinder, and depending on the relative coefficient of friction between them, said circumferential elastic tension can also be such as to cause said inside peripheral face to be fastened at least in part to said outside peripheral face by the mutual friction effect that results from said transverse pressure, which effect can be reinforced by clamping the ferrule onto the outside peripheral face of the cylinder by means of at least one band surrounding the ferrule coaxially and placed under circumferential tension, supposing that such a band is technically feasible, in particular given the conditions under which the pipe or the like is to be installed.

Under such circumstances, and contrary to that which happens in the case of a female endpiece made in accordance with the teaching of U.S. Pat. No. 5,180,196, the band is merely optional and does no more than supplement, if necessary, a natural tendency of the ferrule that is placed in a state of circumferential elastic tension on the outside peripheral face of the cylinder to press elastically against said outside peripheral face, tending to establish mutual sealing and, where appropriate, mutual fastening. Thus, for a pipe or the like in accordance with the invention, instead of the ferrule and the band acting against each other in this respect, they become complementary, and the magnitude of the pressure which the band must apply to the ferrule in order to achieve a required magnitude of transverse contact pressure between the ferrule and the outside peripheral face of the end of the cylinder can remain considerably lower than with a pipe or the like in accordance with the teaching of the above-cited American patent.

Such a pipe of the invention can be made by a method including an initial step consisting in prefabricating a female end ring itself characteristic of the invention, presenting a longitudinal axis and constituting:firstly a longitudinal ferrule defined in particular by a longitudinal inside peripheral face; andsecondly a longitudinal skirt situated axially in line with the ferrule,

the ring being characterized in that the ferrule is elastically expandable circumferentially.

This method, likewise characteristic of the present invention, is itself characterized in that it comprises the following succession of steps:

a) prefabricating the cylinder independently of the ring, the ring being in accordance with the present invention and being dimensioned in such a manner that, at a determined longitudinal distance from the transition between the ferrule and the skirt, and in the absence of the ring being expanded circumferentially, said inside peripheral face presents transverse dimensions that are smaller than those presented by said outside peripheral face at the same longitudinal distance from said front face, but sufficiently close thereto to be capable of being increased to said dimensions by putting the ferrule under circumferential elastic tension; and

b) engaging the ferrule coaxially on the annular end of the cylinder to a determined relative position in which said transition coincides longitudinally with said front face, and fastening the ferrule to the cylinder in said determined relative position by placing said ferrule in a state of circumferential elastic tension providing sealing relative to said outside peripheral face by said inside peripheral face applying thereto transverse pressure that is distributed circumferentially in continuous manner.

When the above-specified conditions are satisfied for said circumferential elastic tension being such that said inside peripheral face is fastened to said outside peripheral face at least in part by a mutual friction effect resulting from said transverse pressure, then this effect can be reinforced by banding the ferrule in said determined relative position.

Step b) can be implemented by engaging the ring via its ferrule coaxially and by force on the annular end of the cylinder. This operation can be made easier if, respectively during the initial step and during step a), the ring and the cylinder are prefabricated in such a manner that said outside peripheral face and/or said inside peripheral face flare relative to their respective longitudinal axes in the longitudinal direction going away from said front face and relative to the transition between the ferrule and the skirt, respectively, preferably ensuring that the outside peripheral face is flared to a greater extent that said inside peripheral face relative to the respective longitudinal axes, thus enabling the engagement to be made progressive. It is also possible to facilitate such engagement by interposing a lubricant between said inside and outside peripheral faces in order to facilitate this operation.

The presence of such a lubricant nevertheless suffers from reducing the effect of mutual fastening by friction that can result from the circumferential elastic tension of the ferrule, and it is preferable to implement step b) in a manner that is characterized in that coaxial engagement of the ferrule on the annular end of the cylinder during step b) is facilitated by placing the ferrule in a state of circumferential expansion greater than that which corresponds to said state of circumferential elastic tension, until said relative position has been reached, and in that the ferrule is allowed to leave said state of circumferential expansion so as to allow said transverse pressure to be established once said relative position has been reached.

For example, the ferrule is placed in said state of circumferential expansion by means selected from the group comprising mechanical means and thermal means.

Various dispositions can be adopted to increase the mutual sealing effect, and where appropriate, the mutual fastening, that is obtained by applying the inside peripheral face of the ferrule under transverse pressure against the outside peripheral face of the cylinder.

In particular, provision can be made for said inside peripheral face to present at least one continuous annular portion in relief providing sealing relative to said outside peripheral face, being in a state of elastic and/or plastic transverse compression thereagainst, and formed integrally with the ferrule.

In particular, when said outside peripheral face and/or said inside peripheral face flare in the longitudinal direction going away from said front face and relative to the transition between the ferrule and the skirt, in particular for the purpose of making it easier to put the ferrule into place on the cylinder, at least one portion of said continuous annular relief can advantageously be provided to be present in the form of a rib.

The term “rib” is used herein to mean a portion in relief that is solid in shape when seen in section on a plane that contains the axis, and in particular a portion in relief formed by a step in the inside peripheral face of the ferrule and suitable for working essentially in compression against the outside peripheral face of the cylinder in order locally to increase the transverse mutual contact pressure between the inside peripheral face of the ferrule and the outside peripheral face of the cylinder around a continuous ring in order to improve relative sealing between them, and in opposition to a sealing lip which would operate for this purpose essentially in bending by having a long thin shape when seen in section on a plane containing the axis of the cylinder.

A person skilled in the art will readily understand that the presence of at least one continuous annular sealing portion in relief on the inside peripheral face of the ferrule can also increase the effect whereby the ferrule is fastened to the cylinder, when the above-specified conditions are satisfied for ensuring that the inside peripheral face of the ferrule is fastened to the outside peripheral face of the cylinder, at least in part, by a mutual friction effect.

Nevertheless, whether as a supplement or as a replacement, and if the transverse pressure between the inside peripheral face of the ferrule and the outside peripheral face of the cylinder is insufficient on its own to guarantee mutual fastening, provision can be made for said inside peripheral face to be fastened to said outside peripheral face by annular adhesive between them, in particular continuously annular adhesive, thus also improving mutual sealing.

A preferred implementation of the method of the invention for this purpose is characterized in that between steps a) and b), a ring of adhesive, in particular a continuous ring, is deposited on a localized zone of said outside peripheral face and/or of said inside peripheral face selected in such a manner that when implementing step b) and thereafter said zone constitutes a zone of mutual contact via said adhesive and of application of said transverse pressure.

To further improve the sealing, it is also possible to provide that the pipe or the like of the invention has at least one continuous ring of a plastic sealing material interposed between said inside peripheral face and said outside peripheral face.

A preferred implementation of the method of the invention for this purpose is characterized in that between steps a) and b), at least one continuous ring of plastic sealing material is placed on said outside peripheral face and/or said inside peripheral face, and in that during step b), said plastic sealing material between said inside peripheral face and said outside peripheral face is caused to be flattened and/or to creep.

For these same purposes of improving sealing, it is also possible to provide for the pipe or the like of the invention to include an annular sealing gasket of elastically compressible material interposed in elastic transverse compression stress between said inside peripheral face and said outside peripheral face, at least in the immediate vicinity of said front face.

A preferred implementation of the method of the invention, for this purpose, is characterized in that between steps a) and b), a sealing gasket of elastically compressible material is put into place on said outside peripheral face at least in the immediate vicinity of said front face, and in that during step b), said gasket is put into elastic transverse compression stress between said inside peripheral face and said outside peripheral face.

Preferably, said outside peripheral face presents an annular setback occupying at least the immediate vicinity of said front face, and said gasket is received over a fraction of its transverse dimension in said setback.

This makes it possible to provide effective retention of the sealing gasket on the outside peripheral face of the cylinder, in particular before and during installation of the ferrule thereon, and for the sealing gasket to benefit from greater thickness, thereby increasing its mechanical strength particularly in shear between the outside peripheral face of the cylinder and the inside peripheral face of the ferrule, and leaving room for a greater elastic compression stroke which is favorable to matching the sealing gasket specifically to the surface state of the outside peripheral face of the cylinder, thereby improving sealing. The localized setback in the outside peripheral face of the annular end of the cylinder is advantageously made during prefabrication thereof, in step a) of the method of the invention, and said gasket is put into place between steps a) and b), being received over a fraction of its transverse dimension in said setback.

Nevertheless, said gasket can advantageously be in the form of a film, and in particular a film which extends from said front face over a longitudinal dimension that is less than the longitudinal dimension respectively of said outside peripheral face and of said inside peripheral face.

To increase the mutual fastening between the ferrule and the cylinder, the inside peripheral face of the ferrule can be fastened to the film constituting the sealing gasket by means of annular adhesive between them, in particular adhesive occupying a continuous annulus, thus also improving relative sealing. To this end, between steps a) and b) of the method of the invention, and after said film has been put into place, a ring of adhesive, in particular a continuous ring, is deposited on a localized zone of said film and/or of said inside peripheral face which is selected in such a manner that when implementing step b) and thereafter said zone constitutes a zone of mutual contact through said adhesive, and of application of said transverse pressure.

Advantageously, if the ferrule of the ring is put into place on the cylinder by progressive forced coaxial engagement of the ferrule on the annular end of said cylinder, the adhesive used for fastening the inside peripheral face of the ferrule with the above-mentioned film and/or for fastening the inside peripheral face of the ferrule with the outside peripheral face of the cylinder is advantageously selected in such a manner that, when in the fresh state, it constitutes a lubricant making said progressive forced engagement easier, while nevertheless being suitable subsequently for providing the desired mutual fastening.

The above-cited film for constituting a sealing gasket between the outside peripheral face of the cylinder and the inside peripheral face of the ferrule can be placed in such a manner that its thickness at rest is substantially constant, or else in such a manner that it presents at least one continuous annular bulge spaced longitudinally from said front face by a distance that is less than the longitudinal dimension respectively of said outside peripheral face and said inside peripheral face, and leading to a longitudinally localized increase in said tension and in said pressure.

This continuous annular bulge can advantageously correspond to a continuous annular groove in the inside peripheral face of the ferrule, and in particular the hardness and the dimensions of said continuous annular bulge can be selected and step b) can be implemented in such a manner that in the determined relative position said continuous annular bulge causes said corresponding continuous annular groove to be formed in the inside peripheral face of the ferrule, in particular by localized plastic deformation thereof. In particular, under such circumstances, step b) is implemented by placing the ferrule in a state of excess circumferential expansion so as to make it easier to engage coaxially on the annular end of the cylinder until their final determined relative position is reached, in which position the ferrule is allowed to leave this state of excess circumferential expansion and establish the transverse pressure that provides relative sealing as described above, and it is during this reduction in the circumferential expansion of the ferrule that, by pressing its inside peripheral face against the bulge of the film forming the sealing gasket that the ferrule is subjected, on coming into contact with said bulge, to localized plastic deformation which gives rise to a continuous annular groove in correspondence with said bulge.

Preferably, in order to facilitate stopping coaxial engagement of the ferrule on the annular end of the cylinder during step b) in the determined relative position, the ring presents internal longitudinal stop means for engaging said front face at the transition between the ferrule and the skirt, said means projecting transversely relative to said inside peripheral face. Under such circumstances, during step b), coaxial engagement of the ferrule on the annular end of the cylinder is stopped when the longitudinal stop means come into abutment against said front face in register with which the stop means remain positioned once the pipe has been completed. The same stop means can be used as a longitudinal abutment for the male endpiece providing they also project transversely relative to a longitudinal inside peripheral face of the skirt.

The stop means can present a variety of shapes, and in particular they can consist in localized projections regularly distributed angularly around the axis, however in a preferred embodiment these stop means comprise a circumferentially continuous transverse annulus of uniform longitudinal dimension. Such an annulus stiffens the ring locally against any increase in its radial and circumferential dimensions, thus contributing to maintaining the circumferential elastic tension state of the ferrule and the transverse pressure between the inside peripheral face of the ferrule and the outside peripheral face of the annular end of the cylinder once the pipe has been made, i.e. to maintaining the mutual sealing effect and, where applicable, the mutual fastening effect, while also providing at least approximate control over the transverse dimension of the skirt, i.e. control within tolerance limits that are acceptable.

The abutment means can be used to retain the film forming the sealing gasket if, between steps a) and b), a transverse annular rim of said film is formed on said front face of the annular end of the cylinder, in which case, during step b), coaxial engagement of the ferrule of the ring on the annular end of the cylinder is stopped when the longitudinal stop means come into abutment against said front face via said rim, which retains this function as an intermediary through which pressure is applied once the pipe has been completed.

Naturally, when assembling a plurality of pipes or the like in accordance with the invention by engaging a male endpiece of one coaxially in the skirt of the female end ring of another, it is necessary for said ring to be placed in sealing relationship not only with the pipe or the like of which it forms a part, but also with the male endpiece of the other pipe or the like.

To this end, provision can be made to mount a sealing gasket on the male endpiece prior to engaging it in the female endpiece, however it is preferable for the ring to be made in such a manner that its skirt is shaped on the inside specifically to receive and to retain at least one transverse annular gasket providing sealing relative to the male endpiece, and during step a) on manufacture of the ring, or subsequent to step b), e.g. on the site where pipes or the like are being installed, at least one transverse annular gasket is secured to the skirt on the inside thereof to provide sealing relative to the male endpiece.

When it is feared that mutual fastening between the ferrule of the ring and the annular end of the cylinder by a mutual friction effect resulting from the inside peripheral face of the ferrule pressing transversely on the outside peripheral face of the annular end and/or from adhesive between the inside peripheral face of the ferrule and the outside peripheral face of the annular end and/or from a sealing film between said faces and/or from locking a continuous annular groove in the inside peripheral face of the ferrule onto a continuous annular bulge of said film will not be sufficient, then those various means of providing mutual fastening can be supplemented or replaced by other means.

One such means consist in transverse pins regularly distributed circumferentially for fastening the ferrule to the cylinder after step b), and another consists in mutual snap-fastening.

To this end, the female end ring is made in such a form that the ferrule presents at least one catch projecting transversely relative to the inside peripheral face of the ferrule in the immediate vicinity of said edge, e.g. a plurality of such catches that are circumferentially localized and regularly distributed circumferentially, all occupying the same longitudinal position. Then, during step a), the cylinder is prefabricated in such a manner as to present at least one depression in said outside peripheral face for receiving said catch at a longitudinal distance from said front face that corresponds to the longitudinal distance between said catch and the transition between the ferrule and the skirt, there being at least one such catch, and step b) of progressively coaxially engaging the ferrule by force on the annular end of the cylinder is implemented by pressing said at least one catch on said outside peripheral face, thereby elastically deforming the ring increasingly, and then enabling the catch(es) to engage in said at least one depression by elastic return once said determined relative position has been reached so as to retain the ferrule longitudinally on the cylinder in said determined relative position after the pipe has been completed. Preferably, during step a), said depression is made in the form of a transverse annular groove in the outside peripheral face of the cylinder, so that the relative angular orientation of the ring and the cylinder about their common axis is immaterial while they are being engaged coaxially in step b), however it would also be possible to provide for each catch to be associated with a respective localized depression.

Given that making a pipe of the invention, in particular using the method of the invention, makes use of a female end ring of special design, the present invention also extends to such a female end ring, presenting a longitudinal axis and constituting:firstly a longitudinal ferrule defined in particular by a longitudinal inside peripheral face; andsecondly a longitudinal skirt situated axially in line with the ferrule,the ring being characterized in that the ferrule is elastically expandable circumferentially.

The ring can also present the preferred characteristics mentioned above with respect to the pipe or the like or the method of manufacturing it;

In addition, the ferrule and the skirt are preferably of respective shapes and transverse dimensions suitable for enabling a plurality of rings to be releasably nested coaxially one in another by mutual coaxial engagement of the ferrule of one ring with the skirt of another. This makes it possible to store female end rings in a minimum amount of space while waiting for assembly to concrete cylinders, in order to make pipes or the like in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

These figures show the invention implemented by making a female endpiece for a pipe in order to provide a leakproof assembly with a male endpiece of another pipe, however a person skilled in the art will readily understand that the present invention can be applied whenever it is necessary mutually to engage in leakproof manner two ducts or other building elements analogous to pipes, in particular those listed in the introduction by way of non-limiting example.

In addition, although the present invention is described below for pipes and female end rings that are both bodies of revolution about a common axis, the invention can also be applied when the pipes or the like present shapes other than being bodies of revolution about their axes, and it comes within the normal aptitudes of a person skilled in the art to adapt the dispositions described below in any manner necessary wherever appropriate.

Insofar as the various implementations of the invention shown in the figures are very analogous to one another, the same numerical references are used to designate elements which correspond from one embodiment to another, specifically: 1 designates the pipe of the invention, 2 its cylinder of tubular shape, in this case a rectilinear cylinder, 3 an annular end thereof, 4 a female end ring of the invention integral with a ferrule5for leakproof connection to the annular end3of the cylinder2and with a skirt6forming a female endpiece for the pipe1,7a male endpiece of another pipe8, which male endpiece7is engaged in leakproof manner in the skirt6forming the female endpiece of the pipe1, and9a longitudinal axis about which the cylinder2, in particular its annular end3, the ring4, in particular its ferrule5and its skirt6, and the pipe8, in particular its male endpiece7are respective bodies of revolution. In the description below, this axis9constitutes the reference for concepts of “axial” or “longitudinal” direction, of “radial” or “transverse” direction, and of “circumferential” direction, and also as a reference for any derived concepts. Similarly, it is considered that an “inside” periphery covers any face looking towards the axis9, an “outside” periphery covers any face looking away from the axis, while the term “frontal” designates any transverse face, whether it is a face of the cylinder2, of the pipe1, of its female end ring4, or of the pipe8.

In accordance with one of the aspects of the present invention, the ring4and the cylinder2are prefabricated separately by molding the cylinder2out of concrete and by molding the female end ring4as a single piece of synthetic material, e.g. polypropylene, or as a single piece of metal, e.g. stainless steel, or indeed by making it as an assembly of a plurality of pieces of metal, these examples of materials and methods of manufacture not being limiting in any way.

As manufactured and as it remains without modification after being assembled with the ferrule5, the cylinder2is defined over its entire longitudinal dimension, and in particular at its annular end3, by a circularly cylindrical inside peripheral face10. At the annular end3, this inside peripheral face10connects with a circularly annular front face11that is plane and perpendicular to the axis9, connecting the inside peripheral face10in a direction going away from said axis9to an outside peripheral face12which is circularly frustoconical, flaring in longitudinal direction13away form the front face11, forming an angle relative to the axis9, which angle is not referenced but is of the order of a few degrees, e.g. 3.5°, this figure nevertheless merely constituting a non-limiting example. In the direction13, the face12is connected to a main outside peripheral face15of the cylinder2by a plane transverse annular shoulder14facing in the direction opposite to the direction13, which peripheral face15is circularly cylindrical and extends in the direction13for example as far as a male endpiece of the pipe1, which male endpiece is not shown but can be identical to the male endpiece7of the pipe8.

Preferably, as shown, the face12connects to the face11via a circularly annular chamfer16. In addition, in the immediate vicinity of its connection with the front face11, i.e. at the chamfer16and over a portion of its longitudinal extent going away from the connection, i.e. from the chamfer16, e.g. over about half its longitudinal dimension between the front face11and the shoulder14, the face12preferably presents an annular setback17preferably made during prefabrication of the cylinder2and designed to receive a sealing gasket18between the annular end3of the cylinder2and the ferrule5of the ring4. In the example shown inFIGS. 5to7, this sealing gasket18implemented in the form of a film of elastically compressible sealing material. e.g. a synthetic rubber having hardness of about 60 DIDC, this material and this hardness being given purely by way of non-limiting example, having a thickness or about 1.7 millimeters (mm) in the absence of compression, this figure likewise being given purely by way of non-limiting example, and the setback17is defined by a wall19having the same cone angle as the face12and set back from it by about half the above specified thickness of the gasket or film18relative to a geometrical extension20of the face12from the chamfer16to a transverse annular shoulder21connecting with the remainder of the face12, which shoulder21is plane, perpendicular to the axis9, and faces in the direction opposite to the direction13. Opposite said shoulder21, i.e. going away from it in the direction opposite to the direction13, the wall19of the setback17connects directly with the chamfer16; correspondingly, and preferably, the film constituting the gasket18is dimensioned in such a manner that once it has been put into place on, the wall19of the setback17so that it is in a state of circumferential elastic extension, it extends in the direction opposite from the direction13from the shoulder21to the chamfer16and goes round the chamfer so as to form a transverse annular rim on the front face11over at least a fraction of the radial extent thereof from the chamfer16and going no further than the connection between said front face11and the face10, the gasket fitting closely to the wall19of the setback17, to the chamfer16, and to the corresponding portion of the front face11, and projecting by about half its thickness relative to the geometrical extension20of the face12between the shoulder21and the chamfer16in the absence of any elastic compression being applied to said gasket or film18.

The sealing film or gasket18is thus put into place on the annular end3of the cylinder2prior to putting the ring4into place via its ferrule5on said annular end3.

The female end ring4is prefabricated in a shape that can be seen inFIGS. 1to5and which is described below. This shape is that in which the ring4is in its rest state, i.e. before it has been subjected to any stress extending it radially and circumferentially, it being understood that securing it to the annular end3of the cylinder2causes its ferrule5to pass to a state in which it is elastically extended circumferentially and radially while the skirt6retains at least approximately its rest shape and dimensions. Nevertheless, the ferrule5and the skirt6are oriented longitudinally and are situated at least approximately longitudinally in line with each other in both states, and they are cantilevered respectively in the direction13and in the direction opposite to the direction13from a transition22between them, which transition forms a circular annulus.

Going from the transition22, the ferrule5is defined by inside and outside peripheral faces respectively23and24which are connected to each other in the direction13, i.e. longitudinally going away from the transition22along a free edge25that constitutes a circular annulus. Similarly, going away from the transition22, the skirt6is defined by inside and outside peripheral faces26and27which extend in the direction opposite to the direction13away from the transition22to a free edge28that is a circular annulus and that is thus longitudinally opposite from the transition22.

Considering the ferrule5in the rest state, as shown inFIG. 5, its outside peripheral face24is substantially a circular-cylinder, it being understood that it could present a small amount of circular conicity converging in the direction13so as to make unmolding easier if the ring4is made as a one-piece molding. Likewise with the ferrule5in the rest state, the inside peripheral face23is in the form of a circular truncated cone which diverges in the direction13so as to form an angle (not referenced) relative to the axis9which is smaller than the angle formed by the outside peripheral face12of the annular end3of the cylinder2relative to the same axis9, being, for example, about 2.5° when the other angle is about 3.5°, these figures being given purely as non-limiting examples. In addition, the ferrule5is dimensioned in such a manner that in the rest state, at a longitudinal distance determined by the transition22, its inside peripheral face23presents transverse dimensions that are smaller than those presented by the outside peripheral face12of the annular end3of the cylinder at the same longitudinal distance from the front face11, but sufficiently close thereto to allow them to be expanded to match, and preferably even further, by putting the ferrule5under circumferential elastic tension; when the face12presents a setback17, the dimensions to be taken into consideration for the above relationship between the dimensions of the inside peripheral face23and the dimensions of the outside peripheral face12are the dimensions of the geometrical extension20of the face12where it overlies the setback17; in addition, in the presence of a rim of the sealing film or gasket18on the front face11of the annular end3of the cylinder2, the longitudinal distance that should be taken into account concerning the face12needs to include the thickness of the rim in question, i.e. this distance should be measured not from the front face11itself, but from the front end of the film or gasket18in the direction opposite from the direction13; naturally, it is generally possible to ignore this thickness of the rim of the film or gasket18because this thickness is relatively small and because of the conical shape of the faces12and23, with the longitudinal distance in question being measured from the front face11in the direction13.

The inside peripheral face23can be smooth, but to improve a subsequent effect of the ferrule5anchoring on the face12, and where appropriate on the sealing film or gasket18, it is preferable for it to have the shape shown inFIG. 3whereby said face23presents at least one and preferably a plurality of continuous annular portions in relief29that are elastically and/or plastically compressible in a transverse direction, and that are integrally formed with the ferrule5, e.g. being present in the form of ribs.

Each of these ribs, defined as specified in the introduction and thus forming a localized projection towards the axis9from a geometrical extension30of the face23in the vicinity thereof, is defined, for example, by a transverse annular shoulder31facing in the direction13and connected to the remainder of the face23going away from the axis9by a circularly cylindrical annular flank32, or for unmolding purposes if the ring4is made by molding, circularly frustoconical, forming relative to the axis9an angle that is smaller than the angle of the remainder of the face23, said flank32connecting the shoulder31in its zone closest to the axis9to the remainder of the face23in the direction opposite to the direction13. When such ribs or other continuous annular portions in relief29are provided in this way, the dimensions to be taken into account for the inside peripheral face23when performing the above comparison with the dimensions of the outside peripheral face12of the annular end3of the cylinder2or of the geometrical extension20of said face12are the dimensions of the face23ignoring the ribs or other portions in relief29, and of the geometrical extension30of said face23where the ribs or other portions in relief29are located.

Going away from the transition22, the inside peripheral face23and the outside peripheral face24extend over a longitudinal dimension that is not greater than and that is preferably less than the dimension of the face12measured between the shoulder14and the front face11, or where appropriate the limit in the direction opposite to the direction13of the rim of the sealing gasket or film18, but greater than the longitudinal distance between the shoulder21of the face11or the above-specified limit of the rim of the sealing gasket or film18. At the free edge25, the inside and outside endpiece faces23and24are connected together by a circularly annular chamfer33presenting longitudinal dimensions that are negligible compared with the longitudinal dimensions of the faces23,24, and12.

At the transition22between the ferrule5and the skirt6, the corresponding outside peripheral faces24and27connect together directly, whereas the corresponding inside peripheral faces23and26preferably connect together as shown via a circularly transverse annulus34that is circumferentially continuous, presenting a longitudinal dimension or thickness that is uniform and that projects towards the axis9from the two inside peripheral faces23and26.

More precisely, the annulus34is defined both in the direction13and in the opposite direction by respective plane circular annular front faces35and36perpendicular to the axis9and connected respectively to the inside peripheral face23and to the inside peripheral face26going away from said axis9. Going towards the axis, these faces35and36are connected together via an inside end face37which could be circularly cylindrical about the axis9but which, for unmolding purposes if the ring is made by molding, is in the form of a truncated circular cone about said axis, e.g. converging in the direction13; nevertheless, the minimum diameter of this end face37is greater than the diameter of the inside peripheral face10of the cylinder2, and is preferably approximately identical to the minimum diameter of the rim of the sealing gasket or film18formed on the front face11at the end3of the cylinder2when such a rim is provided.

As explained below, the face35of the annulus34serves as an abutment for the ring4in the direction13against the front face11of the cylinder2, where appropriate via the rim of the film or gasket18on said front face11, and serves via its face36as an abutment against the male endpiece7of the other pipe8in the direction13relative to the ring4. It could be replaced for these two purposes by internal portions in relief circumferentially localized and distributed around the ring4but circumferentially spaced apart, however implementing the abutment means in the form of a continuous annulus is advantageous in stiffening the skirt6, i.e. in opposing deformation thereof when the ferrule5is subjected to circumferential radial expansion, as described below, in order to mount it on the annular end3of the cylinder2. away from the transition with the skirt6, the skirt is of substantially constant radial thickness substantially identical to and locally greater than the maximum thickness of the ferrule5, i.e. the thickness presented by the ferrule in the immediate vicinity of the transition22.

Starting from the transition22, i.e. the face36of the annulus34, and going in the direction opposite to the direction13, the inside peripheral face26of the skirt6presents a plurality of approximately circularly cylindrical segments38,39, and42, ignoring the slight conical shape converging in the direction13for unmolding purposes if the ring4is made by molding.

The first segment38which connects to the base36in the direction13has a maximum diameter at its end opposite from said connection which is less than the diameter presented by the outside peripheral face24of the ferrule5at its free edge25, but greater than the minimum diameter of the inside peripheral face23, i.e. the diameter it presents where it connects with the face35of the annulus34. Longitudinally opposite from its connection with the face36, the segment38connects with a second one of the above-mentioned segments39via a plane annular shoulder40extending perpendicularly to the axis9and facing in the direction opposite to the direction13. Where it connects with said shoulder40, the minimum diameter of the segment39is greater than the diameter presented by the outside peripheral face24of the ferrule5where it connects with the free edge25, and longitudinally opposite from its connection with the shoulder40, the segment39connects via a circularly annular chamfer41to a third one of the segments42, which segment has a minimum diameter where it connects with the chamfer41that is slightly greater than the diameter presented by the outside peripheral face24of the ferrule5at a longitudinal distance from the free edge25that is equal to the longitudinal distance between the shoulder40and the chamfer41. Longitudinally opposite from its connection with the chamfer41, the segment42connects, via a chamfer43that is likewise circularly annular, to a front face44of the skirt6, which front face is a plane circular annulus extending perpendicularly to the axis9and facing in the direction opposite to the direction13, and it defines the free edge28.

Given the above-specified dimensions for the segments38,38, and42of the inside endpiece face26of the skirt6, compared with the dimensions of the outside peripheral face24of the ferrule5, prefabricated rings4waiting to be mounted on respective cylinders can be stored in a coaxially nested state as shown in FIG.4. In this nested state, the ferrule5of one ring4is engaged in the direction13inside the skirt6of another ring4that is identical and that follows it in the direction13, and this takes place under conditions such that the free edge25of the first ring4bears in the direction13against the shoulder40of the second ring4and the segment42of the inside peripheral face26thereof by forming a transverse abutment for the outside peripheral face24of the ferrule5engaged in this way prevents the rings4from becoming mutually misaligned. Storage can be performed with the coinciding axes9either horizontal or vertical, e.g. by stacking nested rings4, with the bottom ring4resting on the ground or on a pallet via the face44of its free edge28.

It will be observed that because of the simplicity of the shapes of the inside peripheral face26of the skirt6, the undercut formed by the chamfer41between the segments39and42does not impede manufacture by molding using techniques well known to molders, it being understood that it could also be obtained by machining to finish off the ring4as a final manufacturing step.

Going radially away from the axis9, the front face44connects the chamfer43to the outside peripheral face27of the skirt6, which outside peripheral face27presents, like the inside peripheral face26, three approximately circular cylindrical segments about the axis9, but if it is manufactured by molding these segments taper slightly, converging in the direction13, these three segments being referenced46,47,48and following one another in the direction13going away from the face44, and corresponding essentially in a radial direction respectively to the segment42, to the segment39, and to the segment38.

At the transition22, the minimum diameter of the segment48is greater than the maximum diameter presented by the outside peripheral face24of the ferrule5at said transition22, and it connects to the outside peripheral face24of the ferrule5via a circularly frustoconical chamfer49converging in the direction13. The slope of the segment48relative to the axis9is substantially identical to that of the segment38such that the thickness of the skirt6between the segments38and48is approximately constant, and the same applies to the segments47and39. The minimum diameter of the segment47is at its junction with the segment48in the direction13, and these two segments47and48are connected together via a circularly frustoconical chamfer50which corresponds to the shoulder40and which is located relative thereto in such a manner as to maintain substantially constant thickness for the skirt6.

In contrast, in the immediate vicinity of the free edge28of the skirt6, the segment46and the segment42form extra thickness increasing the second moment of area of the skirt6for opposing radial and circumferential elastic expansion thereof, and for this purpose the segment46presents a minimum diameter where it connects with the segment47that is greater than the maximum diameter presented by the segment47where it connects with the segment46, and these two segment47and46are connected together via a plane circularly annular shoulder51extending perpendicularly to the axis9and facing in the direction13.

Once the cylinder2and the ring4presenting the above characteristics have been manufactured, and where appropriate after the sealing gasket or film18has been put into place on the cylinder2in the manner described above, manufacture of the pipe1is terminated by engaging the ferrule5of the ring4coaxially onto the annular end3of the cylinder2in the direction13up to a determined relative position as shown inFIG. 6where the transition22between the ferrule5and the skirt6coincides longitudinally with the front face11, and more precisely where the face35of the annulus34comes into abutment in the direction13against said face11, where appropriate via the rim of the film or gasket18on said face11.

Given the dimensional characteristics of the inside peripheral face23of the ferrule5relative to those of the outside peripheral face12of the annular end3of the cylinder2, including the sealing gasket or film18, if any, this coaxial engagement can be achieved by forcing the inside peripheral face23of the ferrule5against the outside peripheral face12of the annular end3of the cylinder2, optionally carrying the sealing gasket or film18, thereby progressively putting the ferrule5into a state of circumferential elastic tension which reaches its maximum when, relative to the cylinder2, it reaches the determined position in which the face35of the annulus34bears in the direction13against the front face11, possibly via the rim of the sealing gasket or film18. Once this determined relative position has been reached, the circumferential elastic tension in the ferrule5is such that via its inside peripheral face23it applies transverse pressure that is continuously distributed circumferentially over the face12alone, in the absence of the setback17and the sealing gasket or film18, or if such a sealing gasket or film18is present, firstly against said sealing gasket or film18thereby compressing it transversely, and secondly against the face12beyond the shoulder21in the direction13, with this transverse pressure establishing leaktightness between them, which leaktightness is increased if there are any ribs or other portions in relief29present, since they create additional transverse pressure around respective continuous transverse rings.

This radial pressure applied by the inside endpiece face23of the ferrule5against the outside peripheral face12of the annular end3of the cylinder2which fits closely thereagainst, and where present, the sealing gasket or film18against which the face23also fits closely and which in turn fits closely over the wall19of the setback17, can be sufficient to provide by mutual friction all or part of the fastening between the ferrule5, i.e. the ring4, and the cylinder2, depending on the friction coefficients relating to the various materials thus put into mutual contact, on the slopes of the faces12and23relative to the axis9, and on the areas of mutual contact.

Such conditions can be satisfied particularly when there is no need to apply lubricant between the inside peripheral face23and the outside peripheral face12and the sealing gasket or film18for the purpose of putting the ring4via its ferrule5into place on the end3of the cylinder, i.e.:either because mounting is performed by forced engagement in the absence of a setback17and a sealing gasket or film18; or elsein the presence or absence of the setback17and the sealing gasket or film18, when the ring4is mounted using a method that is described below with reference toFIGS. 12to17.

When such conditions are satisfied, the effect of mutual fastening by friction between the inside peripheral face23of the ferrule5and the outside peripheral face12of the annular end3of the cylinder2can be reinforced by banding the ferrule5after it has reached the determined relative position shown inFIG. 6, using at least one band91placed coaxially around the outside peripheral face24of the ferrule5, preferably in the immediate vicinity of its free end25, as shown in chain-dotted lines inFIG. 6, and after it has been put under circumferential tension using means known to the person skilled in the art so as to increase the pressure applied via the ferrule5between the inside peripheral face23and the outside peripheral face12. It will be observed that this banding also has the effect of increasing leaktightness between these faces12and23.

In contrast, if mounting is performed by forced engagement under conditions that require lubricant to be present between the inside peripheral face23of the ferrule5and the outside peripheral face12of the annular end3of the cylinder2and optionally the sealing gasket or film18, then the fastening obtained in this way by friction can be insufficient, specifically because the lubricant continues to be present, in which case it must be complemented by suitable means, an example being described below with reference toFIGS. 5 and 6and other examples being described for variant embodiments of the invention with reference toFIGS. 9 and 11.

The means shown inFIGS. 5 and 6consist, prior to forced engagement of the ferrule5on the annular end3of the cylinder2, and then while said engagement is taking place, in creating a film of adhesive which, while fresh, acts as lubricant to facilitate longitudinal sliding of the face23over the sealing gasket or film18, if any, and over the outside peripheral face12of the annular end3of the cylinder2, and subsequently, once the limit position has been reached in which the face35of the annulus34bears in the direction13against the front face11, optionally via the rim of the sealing gasket or film18, the adhesive sets between the inside peripheral face23of the ferrule5and the outside peripheral face12of the annular end3of the cylinder2and the sealing gasket or film18, if any, thereby fastening the ferrule5with the ring4to the cylinder2and the gasket or film18, if any, by adhesion in the zone where they are mutually in contact.

So long as care is taken to ensure that such mutual adhesion takes place around a circumferentially continuous ring, it also serves to improve leaktightness.

In particularly advantageous manner, as shown inFIG. 5, the adhesive is applied prior to the ferrule5being engaged on the annular end3of the cylinder2in the form of a continuous ring52over a zone of the outside peripheral face12that is selected in such a manner that during forced engagement it constitutes a zone of contact with the inside peripheral face23of the ferrule5, e.g. in the immediate vicinity of the shoulder21when a setback17and a sealing gasket or film18are provided, or indeed in the immediate vicinity of the chamfer16in the absence of such a setback17and such a sealing gasket or film18. When such a sealing gasket or film18is provided, another continuous ring of adhesive53can be placed thereon in the immediate vicinity of the transition between the setback17and the chamfer16. Thus, as forced engagement progresses, the face23entrains the adhesive of the ring53and the adhesive of the ring52in succession so as to spread said adhesive over the sealing gasket or film18and over the face12, respectively, in the mutual contact zone while conserving the circumferential continuity of each ring of adhesive that is spread in this way.

In a variant, and in a manner that is not illustrated, the adhesive could also be deposited as a plurality of rings, in particular continuous rings, over the sealing gasket or film18, if any, and/or over the outside peripheral face12of the annular end3of the cylinder2, or indeed as one or more continuous annular rings on the inside peripheral face23of the ferrule5in zones suitably selected to constitute zones of mutual contact during the process of forced engagement and at the end of said process, with this preferably being done from the beginning of the process.

Also in non-illustrated manner, but in a manner that will easily be understood from that described above for improving leaktightness between the faces12and23by means of at least one continuous ring52of adhesive, said leaktightness could be improved or indeed established, e.g. in the absence of the sealing film18, by replacing adhesive in the provision of said ring with a plastic sealing material, commonly referred to as “compound”, which is caused to be flattened out and/or to creep between the faces12and23as the above-mentioned engagement process is taking place so that by the end of said process at least one continuous sealing ring has been formed between said faces12and23. Like the above-described adhesive, the plastic sealing material could also be disposed in at least one continuous ring on the inside peripheral face23of the ferrule in at least one zone selected to constitute a contact zone with the outside peripheral face12of the cylinder2during the process of forced engagement and at the end thereof. The sealing provided by the plastic sealing material can replace the sealing provided by the gasket18or can be additional thereto in a zone in which said gasket18is not interposed between the faces12and23.

At the end of engagement, i.e. when the annulus34comes into abutment via its face35in the direction13against the front face11at the annular end3of the cylinder2, possibly via the rim of the gasket or film18as shown inFIG. 6, the skirt6projects longitudinally from the front face11in the direction opposite to the direction13, thereby constituting a female endpiece54for the pipe1in line with the annular end3of the cylinder2to which the skirt6is fastened by means of the ferrule5.

This female endpiece54is intended to receive the male endpiece7of the pipe8by longitudinal engagement in the direction13, and as shown in FIG.8.

To this end, and relative to the shape of the skirt6, the male endpiece7presents the known shape for a male endpiece given the shape of the female endpiece in which it is to engage. It can thus present any known design.

In the example shown, the male endpiece7is integrally molded as a single piece of concrete with a cylinder55of the pipe8, which cylinder is entirely analogous to the cylinder2of the pipe1(which in turn can also present a male endpiece identical to the male endpiece7), and it is located at its end longitudinally opposite from its annular end3having the ring4fitted thereon, and in like manner the cylinder55of the pipe8can be provided with a ring analogous to the ring4at its end longitudinally opposite from its male endpiece7.

In the example shown, and if the male endpiece7is assumed to be occupying a finally engaged position inside the female endpiece54constituted by the skirt6, as shown inFIG. 8, then the male endpiece7is defined towards the axis9by an inside peripheral face56common to the entire cylinder55and constituting a circular cylinder having the same diameter as the face10which is extended longitudinally in the direction opposite to the direction13by said face56. In the direction13, the face56connects to a front face57of the cylinder55, which face is a plane circular annulus perpendicular to the axis9and faces in the direction13. Radially opposite from its connection with the face56, the face57presents a maximum diameter which is intermediate between the minimum diameter of the face36of the annulus34of the ring4, i.e. the minimum diameter of the end face37of said annulus34, and the minimum diameter of the segment28of the inside peripheral face26of the skirt6of the ring4, so that the cylinder55of the pipe8bears flat in the direction13via its face57against the face37of the annulus34, and via said annulus and the rim of the sealing gasket or film18, if any, against the front face11of the annular end3of the cylinder2of the pipe1.

Via its greatest diameter as defined in this way, the front face57connects via a circularly frustoconical chamfer58that converges in the direction13to an outside peripheral face59of the male endpiece7, which face is likewise circularly frustoconical, converging in the direction13and forming an angle relative to the axis9that is of substantially the same size as the angle formed relative to said axis by the outside peripheral face12of the annular end3of the cylinder2. At a longitudinal distance from the front face57that is greater than the longitudinal distance between the front face44of the skirt6of the ring4and the face36of its annulus34, the outside peripheral face59connects via a chamfer (not referenced) to a circularly annular shoulder60that is plane and perpendicular to the axis9, facing in the direction13, thereby connecting the outside peripheral face59to a main outside peripheral face61of the cylinder55which is advantageously circularly cylindrical, having a diameter that is identical to that of the main outside peripheral face15of the cylinder2of the pipe1, it being possible for the two pipes1and8to be identical.

Various means can be provided for providing leaktightness between the male endpiece7and the female endpiece54constituted by the skirt6, and in particular, and in conventional manner, this can be done by mounting an annular sealing gasket on the outside peripheral face59of the male endpiece7. Under such circumstances, the segment38of the inside peripheral face26of the skirt6of the ring4can extend without discontinuity in the longitudinal direction from the face36of the annulus34to the front face44of the skirt6, and likewise the segment48of the outside peripheral face27of this skirt6can extend without discontinuity from the chamfer49to said front face44, the setbacks constituted by the shoulder40and the chamfer41in the face26being omitted as is the projection formed on the face27by the chamfers50and51and by the segments46and47of the outside peripheral face.

Such an embodiment is not shown and comes within the normal competence of a person skilled in the art concerning the above modification in the shape of the skirt6of the ring4.

To provide leaktightness, it is also possible for the inside of the skirt6to be fastened prior to longitudinal engagement on the male endpiece7to at least one transverse annular sealing gasket facing the male endpiece7.

Such a transverse sealing gasket can be mounted when the ring4is prefabricated, or as shown inFIG. 7, it can be mounted after the ring4has been fastened via its ferrule5on the annular end3of the cylinder2as shown in FIG.6and before the male endpiece7of the pipe8is engaged as shown in FIG.8.

In the example shown, only one annular sealing gasket62is provided inside the skirt6, and this annular sealing gasket62is fixed and held on the segment39of the inside peripheral face26, e.g. by adhesive, between the shoulder40and the chamfer41which contributes to preventing it from sliding longitudinally relative to the skirt6during engagement of the annular sealing gasket62in a circularly annular groove63defined as a recess in the inside peripheral face26by the shoulder40, the chamfer41, and the segment39.

More precisely, the sealing gasket62which is made of an elastically compressible sealing material such as a synthetic rubber presents a longitudinal and circularly annular sleeve64complementary in shape to the groove63so as to engage therein, and so as to enable it to be fixed to the skirt6of the ring4, e.g. by being stuck to the segment39of the inside peripheral face26, together with an annular transverse sealing portion in relief65projecting radially towards the axis9from the sleeve64and geometrically extending the segment38of the inside peripheral face36of the skirt6of the ring4. When the sealing gasket62is at rest, i.e. when it is not subjected to any stress as is the case prior to the male endpiece7of the pipe8being longitudinally engaged in the female endpiece54defined by the skirt6, this projection is of radial dimension such that during said engagement the portion in relief65comes into contact under pressure against the outside peripheral face59of said male endpiece7, thereby pushing back said portion in relief65in the direction13(which is the engagement direction) and compressing the portion in relief65against the sleeve64, which itself can optionally be compressed going away from the axis9against the segment39of the inside peripheral face26of the skirt6of the ring4so as to provide leaktightness between said skirt4and the male endpiece7.

The way in which the portion in relief65is shaped and dimensioned for this purpose is readily determined by a person skilled in the art. As a non-limiting example, the portion in relief65is defined in the example shown and when in the rest state as shown inFIG. 7by a circularly frustoconical upstream flank66converging in the direction13and forming an angle of about 45° relative to the axis9, and by a circularly annular downstream flank67which is plane and perpendicular to the axis9, where the concept of upstream and downstream are relative to the direction13. The portion in relief65is located approximately in the upstream half of the gasket62whose downstream portion is defined by the sleeve64which then presents an inside peripheral face68constituting a circular cylinder. Once the male endpiece7of the pipe8has been engaged fully in the female endpiece54defined by the skirt6of the ring4, i.e. once the front face57comes to bear flat in the direction13against the face36of the annulus34, as shown inFIG. 8, the portion in relief65is folded downstream against the sleeve64under conditions such that its face67is snug against the face68, with the assembly constituted by the portion in relief65and the sleeve64being compressed away from the axis9against the segment39of the inside peripheral face26of the skirt6of the ring4so as to provide leaktight sealing. Naturally, the sleeve64and the portion65of the sealing gasket62are circumferentially continuous for this purpose.

The description above with reference toFIGS. 5to8describes how the ferrule5of the ring4can be fastened to the annular end3of the cylinder2either by friction or by adhesive.

FIG. 9shows a technique relying on snap-fastening, which can be in addition to or instead of the above two fastening techniques.

InFIG. 9, the various portions of the cylinder2and of the ring4as described above with reference toFIGS. 5 and 8are shown again identically and using the same numerical references, with theFIG. 9variant differing from that described with reference toFIGS. 5to8only in the additional characteristics that are described below.

One of these characteristics consists in the ferrule of the ring4, as prefabricated, presenting at least one fastening catch in relief69in the immediate vicinity of its free edge25and projecting from its inside peripheral face23, the catch69being designed to engage the outside peripheral face12of the annular end3of the cylinder2, and preferably being provided in the form of a plurality of catches each localized circumferentially and together distributed regularly around the circumference, and all occupying the same longitudinal position. The person skilled in the art can easily determine the number of catches69needed to achieve the mechanical strength required to prevent the ferrule5becoming detached longitudinally from the annular end3of the cylinder2.

In the example shown, each of these catches69presents on its upstream side relative to the direction13, a flank70that is plane and perpendicular to the axis9, and on its downstream side, a convex flank71presenting a section in a plane that includes the axis9which is curved, e.g. circularly arcuate, similar to the chamfer33, so that the flank70connects to the outside peripheral face24of the ferrule5.

The cylinder2is prefabricated in such a manner as to present a continuous transverse annular groove72in its outside peripheral face12in which the catches69can engage, as represented by chain-dotted lines inFIG. 9, once the ring4, on being engaged longitudinally on the cylinder2, reaches the determined limit position in which it comes into abutment via the face35of the annulus34against the front face11of the annular end3of the cylinder2, and via the rim of the sealing gasket or film18, if any.

To this end, the groove72is defined on the upstream side relative to the direction13by an annular flank73that is plane, extending transversely perpendicularly to the axis9and facing in the direction13, said flank73being situated at a longitudinal distance from the front face11or from the upstream limit of the sealing gasket or film18, if any, on said front face11that is substantially equal to the longitudinal distance between each of the upstream facing flanks70of the catches69and the face35of the annulus34. In addition, the groove72is defined by a downstream flank74that is likewise plane, annular, and perpendicular to the axis8, but faces in the direction opposite to the direction13, said flank74being spaced apart longitudinally from the flank73by a distance that is not less than the distance between each flank70and the free edge25of the ferrule5of the ring4, and by a circularly frustoconical bottom wall75having a cone angle identical to that of the outside peripheral face12, with said bottom wall75being set back therefrom by a depth that is not less than the transverse dimension of each flank70.

The ring4is thus mounted on the cylinder2by progressive forced coaxial engagement of the ferrule5in the direction13onto the annular end3of the cylinder2, possibly using a lubricant as described above, with the catches69pressing via their flanks71against the outside peripheral face12, and against the sealing gasket or film18, if any, and with the ring4progressing in the direction13relative to the cylinder2, thereby causing the ferrule to be increasingly deformed elastically in a radially outward direction and in a circumferential direction until the face35of the annulus34comes into abutment against the front face11, via the rim of the gasket or film18, if any. The flank70of each catch69then coincides with the flank73of the groove72and the natural tendency of the ferrule5to return elastically to its original shape causes the catches69to engage in the groove72until they occupy a position in which their flanks70bear against the flanks73of the groove in the direction opposite to the direction13, thus fastening the ferrule5, i.e. the ring4, to the cylinder2against separation in the longitudinal direction.

The person skilled in the art will readily understand that the groove72could be replaced by as many depressions in the outside peripheral face12as there are catches69without that going beyond the ambit of the present invention.

In another variant, shown inFIG. 11, it is also possible to fasten the ferrule5, i.e. the ring4, to the annular end3of the cylinder2by transverse pins that are regularly distributed circumferentially, e.g. by means of radial rivets76passing through the ferrule5in a zone situated beyond, in the direction13, the setback17for receiving the sealing gasket18, and anchored in respective blind holes pierced in the outside peripheral face12of the annular end3of the cylinder2. These rivets could be replaced by screws, or by any other mechanical means for directly fastening the ferrule5to the annular end3of the cylinder2without that going beyond the ambit of the present invention. The number of pins required for providing the required degree of fastening can readily be determined by the person skilled in the art.

FIG. 11also shows a setback17of a shape that is different from that described with reference toFIGS. 5to8, together with an associated different shape for the sealing gasket18which is held in radial sealing compression against the inside peripheral face23of the ferrule5and which does not have a rim extending over the front face11of the annular end3of the cylinder2. Nevertheless, it should be understood that regardless of the way in which the ferrule5is fastened to said annular end3, sealing between them can be provided by any of the means described with reference toFIGS. 3,5to9, and11, with any compatible combination between the various dispositions described and shown in the present specification being considered as coming within the ambit thereof.

Thus,FIGS. 18 and 19show a variant implementation of the present invention combining various dispositions that are described above.

Thus, the variant shown inFIGS. 18 and 19is similar to the variant shown inFIG. 11in that it uses a sealing gasket18which does not have a rim on the front face11of the annular end3of the cylinder2.

In this variant, the setback17is narrowly located at the junction between the front face11and the outside peripheral face12of the annular end3of the cylinder2in that its bottom wall19is of much smaller longitudinal size, compared with the longitudinal size of the outside peripheral face12than is the case in the variants described with reference toFIGS. 5to10. In contrast, the shoulder21which defines the setback17in the direction13presents a radial dimension greater than that which is presented in the above-mentioned variants, relative to the radial dimension (not referenced) between the outside peripheral face12(e.g. where it joins the shoulder21) and the inside peripheral face10of the cylinder2. In the example shown, the bottom wall19and the shoulder21defining the setback17are both circularly frustoconical about the axis9(not shown inFIGS. 18 and 19) and they flare in the direction13with the shoulder21flaring more than the bottom wall19, and the transition between the shoulder21and the outside peripheral face12of the annular end3of the cylinder2presents a diameter of substantially the same size as that of the free edge25of the ferrule5of the ring4when said ferrule5is in the rest state as shown in FIG.18.

In association with a setback17of this shape, the sealing gasket18has a “drop” shape which, when seen in section on an axial plane as is the case inFIGS. 18 and 19, comprises a flat zone91and an enlarged zone92respectively constituting a downstream zone and an upstream zone relative to the direction13.

The sealing gasket18is shaped and dimensioned in such a manner as to be mounted on the end3of the cylinder2in a state of circumferential elastic extension, and in a position in which:the flat zone91fits snugly against the marginal portion of the outside peripheral face12immediately adjacent to the shoulder21, from which said zone19extends in the direction13over a longitudinal distance that is much shorter than the longitudinal distance between the shoulders14and21, being for example about one-third of said longitudinal distance; andthe zone92bent towards the axis9relative to the zone91fits snugly against the shoulder21and at least a portion of the bottom wall19immediately adjacent to said shoulder21, thereby contributing to holding the gasket18against being moved in the direction13over the annular end3of the cylinder2while the female end ring4is being put into place on said end3under conditions that are described below, and forms an axial projection in the direction opposite to the direction13relative to a coplanar geometrical extension (not shown) of the front face11of the end3of the cylinder2when, as shown inFIG. 18, the female end ring4is not yet in place on the annular end3of the cylinder2.

When in the rest state as shown inFIG. 18, the female end ring4is of the shape described with reference toFIGS. 1to5except that instead of being smooth or instead of having a plurality of longitudinally distributed continuous annular portions in relief as shown inFIG. 3, e.g. constituted by ribs that are elastically and/or plastically compressible transversely, the inside peripheral face23of the ferrule5has only one such continuous annular portion in relief29that is elastically and/or plastically compressible transversely, that is integrally formed with the ferrule5and that is situated at a longitudinal distance from the face35of the annulus34that is greater than the longitudinal distance between the front face11and the downstream limit of the gasket18relative to the direction13, although shorter than the longitudinal distance between the free edge25of the ferrule5and the face35of the annulus34. More precisely, the portion in relief29is substantially closer, longitudinally, to the free edge25than to the face35.

In the example shown, this portion in relief29is defined by a shoulder facing in the direction13and interconnecting two zones that are not referenced but both belonging to the inside peripheral face23and that has substantially the same cone angle when the ferrule5is in the rest state, as shown in FIG.18.

The skirt6of the ring4is of a shape that is completely identical to that described above, and in particular it is suitable for receiving internally and retaining a gasket62that is identical to that described with reference toFIGS. 7 and 8and suitable for providing leakproofing relative to a male endpiece7of a cylinder55of a pipe8, e.g. one identical to the pipe1, under the same conditions as those described with reference toFIGS. 7 and 8, and as shown in FIG.19.

The ring4designed in this way is mounted and fastened to the end zone3of the cylinder2under conditions that are identical to those described above with reference toFIGS. 5 and 6, either before or after the gasket62has been put into place in the skirt6.

In particular, prior to engaging the female end ring in the direction13by force on the end zone3of the cylinder2provided with the sealing gasket18, respective continuous annular beads of adhesive53and54that are circular about the axis9are placed on an annular location of the zone92having a diameter approximately identical to that of the free edge25of the ferrule5, i.e. where initial contact is made between the ferrule5and the gasket18when the ferrule of the ring4is engaged coaxially by force on the end3, in the direction13, and at the downstream limit of said gasket18relative to the direction13, i.e. more precisely at the transition between the zone91of said gasket and the outside peripheral face12of the end zone3of the cylinder2. Thus, as the ferrule5of the ring4is progressively forced onto the end3in the direction13, the inside peripheral face23of the ferrule5entrains in succession the adhesive of the bead53and then the adhesive of the bead54and it spreads said adhesive over the zone91of the gasket18and over the portion of the outside peripheral face12of the end zone3that is progressively covered by the inside peripheral face23of the ferrule5.

The presence of the annular portion in relief29makes such spreading of the adhesive in the bead53and then in the bead54easier, making it possible initially to create a thin film of still-fresh adhesive that is continuous both in the circumferential direction and in the longitudinal direction between the inside peripheral face23and both the sealing gasket18and the outside peripheral face12, thereby easing relative longitudinal sliding, and then, as this adhesive sets, creating fastening that is likewise as continuous as possible both in the circumferential direction and in the longitudinal direction between the inside peripheral face23and both the sealing gasket18via its zone91and the outside peripheral face12.

This engagement movement of the ferrule5of the female end ring4under force over the end zone3of the cylinder2causes the zone91of the gasket18to be compressed progressively in the radial direction between the inside peripheral face23of the ferrule5which is progressively being extended elastically in the circumferential direction and the outside peripheral face12of the annular end3of the cylinder2, thereby providing effective sealing at the gasket, and then causes the zone92to be elastically compressed in the longitudinal direction between the face35and the shoulder21and the bottom wall19of the setback17, thereby also establishing sealing at this location when the face35of the annulus34of the ring4comes into abutment in the direction13against the front face11of the annular end3of the cylinder2, thus defining the final relative position of the ring4relative to the cylinder2, as shown in FIG.19.

In this position, the inside peripheral face23of the ferrule5, which is in a state of elastic circumferential extension, presses elastically against the outside peripheral face of the annular end3of the cylinder2in two zones, namely:indirectly via the zone91of the gasket18in the portion of the face12covered by said zone91; anddirectly via the annular portion in relief29; and possibly also in a third zone, i.e. directly at the free edge25.

This provides particularly effective sealing between the ferrule5and the annular end3of the cylinder2, with this sealing being further increased by the face35of the annulus34pressing against the zone92of the gasket18.

The ring4is thus likewise fastened in particularly effective manner via its ferrule5to the annular end3of the cylinder2, both because of the presence of the adhesive and because of the mutual compression in a direction that is approximately radial relative to the axis9.

The person skilled in the art will readily understand that other variations in implementation and relative positioning of the female end ring4, of the sealing gasket18, and of the annular end of the cylinder2, are all possible without thereby going beyond the ambit of the present invention, in particular by combining various ones of the dispositions described and shown above.

Thus, although the ferrule5is described with reference toFIGS. 5to9,11,18, and19as being mounted on the annular end3of the cylinder2by progressive forced engagement, generally with an interposed lubricant which can advantageously be constituted by an adhesive that subsequently contributes to mutual fastening and leakproofing, it is also possible for the ferrule5of the ring4to be subjected temporarily to radial and circumferential elastic expansion while it is being engaged coaxially on the annular end3by using means other than pressing against the outside peripheral face12of said annular end3and of the sealing gasket or film18, if any, for the purpose of making such forced engagement easier or even for replacing it with mere mutual engagement without compression and consequently without friction between the inside peripheral face23of the ferrule5of the ring4and the outside peripheral face12of the annular end3of the cylinder2, and of the sealing gasket or film18, if any, with the ferrule5subsequently being allowed to return to a state in which it applies such mutual compression only after it has reached the limit position in which the face35of the annulus34bears flat in the direction13against the front face11of the annular end3of the cylinder2, and via the rim of the sealing gasket or film18, if any.

Such an implementation presents the advantage of making it possible to omit any lubricant between the inside peripheral face23of the ferrule5of the ring4and the outside peripheral face12of the annular end3of the cylinder2, and the sealing gasket or film18, if any, consequently encouraging mutual fastening by friction, possibly without adding any additional fastening means.

To this end, it is possible to heat the ring4so as to cause it to expand thermally on a temporary basis, and to remove heating once the ring has reached its limit position for longitudinal engagement on the annular end3of the cylinder2, and this can be sufficient when the outside peripheral face12of the annular end3of the cylinder2and of the sealing gasket or film18, if any, and when the ferrule5of the ring4have the shape described with reference toFIGS. 3,5to8, or9, and concerning the sealing gasket18, the shape described with reference to FIG.11. It is also possible to use mechanical means for this purpose, using a method which is described with reference toFIGS. 12to17, both with shapes as described with reference toFIGS. 3,5to9, and11, and more particularly with a shape that is described below with reference to FIG.10.

In this figure, there can be seen the cylinder2, the ring4, and the sealing gasket or film18identical to those described with reference toFIGS. 5to8, and having the same numerical references for their various components, with the exception of the differences described below.

At rest, i.e. before being put into place on the cylinder2, the ring4is completely identical to that described with reference toFIGS. 1to5. In contrast, although the sealing gasket or film18remains uniform where it has a rim over the front face11of the annular end3of the cylinder2, over the chamfer16thereof, and over the most part of its longitudinal extent going away from the chamfer16to the vicinity of the shoulder21of the setback17, in the immediate vicinity of said shoulder21it presents a continuous annular bulge77forming a ring which is circular in section on any section plane containing the axis9, the sealing gasket or film18being described prior to the ring4having its ferrule5put into place on the annular end3of the cylinder2. To receive a corresponding portion of the bulge77, the bottom wall19of the setback17is locally indented in the immediate vicinity of the shoulder21to form a continuous annular groove78whose section is that of a circular arc on any plane that contains the axis9so as to be able to receive this portion of the bulge77, whereas the remainder thereof projects radially away from the axis9from the outside peripheral face12of the annular end3of the cylinder2and also from the portion of the sealing gasket or film18which lies on the bottom wall19of the setback17.

The person skilled in the art will readily understand that when the ferrule5presses its inside peripheral face23against the outside peripheral face12of the annular end3of the cylinder2and against the sealing gasket or film18on respective opposite sides of the bulge77, this bulge77gives rise to a longitudinally localized increase in the circumferential tension of the ferrule5and in the contact pressure against the inside peripheral face23thereof.

Preferably, as shown inFIG. 10, where chain-dotted lines represent the position of the ferrule5when the ring4is pressed via the face35of the annulus34against the front face11of the annular end3of the cylinder2through the rim of the sealing gasket or film18, the hardness and the dimensions of the bulge77are selected and the ring4is put into place via its ferrule5on the annular end3of the cylinder2and on the sealing gasket or film18in such a manner that, in this limit position, the bulge77causes a corresponding continuous annular groove79to be formed in the inside peripheral face23of the ferrule5having a shape that is exactly complementary to the portion of the bulge77that projects from the outside peripheral face12of the annular end3of the cylinder2and from the portion of the sealing gasket or film18that corresponds to the bottom wall19of the setback17, and does so in particular by giving rise to localized plastic deformation of the ferrule5.

To this end, and in order to enable the ferrule5to go past the bulge77of the sealing gasket or film18while it is being put into place thereon and on the outside peripheral face12of the annular end3of the cylinder2without difficulty and without giving rise to damage, it is preferable for this installation to be performed by the method described below with reference toFIGS. 12to17, it being understood that in certain conditions it would still be possible to put the ferrule in place as a force-fit as described with reference toFIGS. 1 and 9to11, or by temporary thermal expansion of the ring4, and in particular of its ferrule5, even when the sealing gasket or film18presents a bulge77as described with reference to FIG.10.

For mounting the ring4via its ferrule5on the annular end3of the cylinder2,FIGS. 12to17show the use of a method which consists in causing the ferrule5temporarily to take up a state of circumferential expansion that is greater than the circumferential expansion it will occupy once it is resting against the outside peripheral face12of the annular end3of the cylinder2and on the sealing gasket or film18generating its own pressure for sealing purposes. This enlarged state is maintained temporarily, i.e. for the time required to move the ring4in longitudinal translation relative to the annular end3of the cylinder2until the face35of the annulus34comes to bear flat against the front face11of the annular end3of the cylinder2, via the rim of the sealing gasket or film18, if any. The ferrule5is then allowed to leave this circumferentially extended state so that the elasticity of the ferrule5establishes the required transverse pressure once the said relative position has been reached.

Instead of using thermal means for temporarily expanding the ring4, and in particular its ferrule5, it is possible to cause such temporary expansion by mechanical means in this version of the method as shown inFIGS. 12to17.

FIG. 12shows the ring4in the rest state and, on the same axis as the ring4and longitudinally facing the free edge25of the ferrule5, there can also be seen an annular tool80for expanding the ferrule5circumferentially and radially.

This tool80is essentially constituted by a semi-rigid hoop81which is described in this position of axial alignment with the ring4.

In the rest state shown inFIG. 12, the hoop81is defined towards the axis9and going away from the axis9by an inside peripheral face82and by an outside peripheral face83, respectively, both being circular cylinders about the axis9, and between these faces82and83the thickness of the hoop81is as small as possible while nevertheless being sufficient to ensure that it has mechanical strength suitable for the use described below. In the direction13and in the direction opposite to the direction13, the faces82and83are connected together respectively by a downstream front face84and by an upstream front face85, both of which are circular annuluses about the axis9, plane, and perpendicular to the axis. Between the two front faces84and85, the hoop81presents a longitudinal size or length that is no longer than that of the face23between the face35of the annulus34and the free edge25, and that is preferably no greater than or approximately equal to the difference between said longitudinal side of the face23and the longitudinal distance between the bulge77of the sealing gasket or film18and the front face11of the annular end3of the cylinder2or the extreme limit of the rim of the sealing gasket or film18, if any, on said front face11. The inside peripheral face82has a diameter greater than the maximum diameter of the bulge77and greater than the diameter presented by the face12at a longitudinal distance from the free edge25of the ferrule5when it bears flat via the face35of the annulus34against the front face11of the annular end3of the cylinder2, via the rim, if any, of the sealing gasket or film18on said front face11, which distance corresponds to the longitudinal size of the hoop81between its front faces84and85.

On its downstream front face84the hoop81carries a plurality of rigid tabs86that are uniformly distributed angularly around the axis9(apart from two of them which are adjacent to each other), the tabs projecting radially from the outside peripheral face83, i.e. away from the axis9, without projecting radially from the inside peripheral face82, i.e. towards the axis9. By way of non-limiting example, two of these tabs86are shown as being in diametrically opposite positions, a third tab86on a diameter perpendicular to the diameter between the above-mentioned two tabs86, and two more tabs86are adjacent to each other and placed symmetrically about a position that is diametrically opposite to the above-mentioned third tab86.

Between these two adjacent tabs86, the hoop81is split obliquely, i.e. on a plane that is not referenced and that is oblique relative to the axis9so as to define two plane end faces87perpendicular to the inside and outside peripheral faces82and83but oblique, e.g. at 45°, relative to the front faces84and85. When the hoop81is in the rest state, as shown inFIG. 12, these two end faces87press against each other in the circumferential direction so as to cause the hoop81, its peripheral faces82and83, and its front faces84and85to appear to be continuous.

Nevertheless, starting from this rest state and as shown inFIG. 13, it is possible to offset one of the end faces87relative to the other so that they slide longitudinally over each other in a direction compatible with the oblique section, where necessary after putting the hoop81under stress, thus enabling the diameter of the inside and outside peripheral faces82and83thereof to be reduced, and in particular reducing the diameter of the outside peripheral face83to a value which is smaller than the diameter of the inside peripheral face23of the ferrule5in the vicinity of its edge25. The hoop81can thus be inserted in the direction opposite to the direction13into the ferrule5so that its outside peripheral face83comes against the inside peripheral face23of the ferrule until the tab86closest to the end face87which is offset upstream relative to the direction13relative to the other end face87comes to bear in the direction opposite to the direction13against the free edge25, with at least one other tab close to the same side of the split in the hoop81coming to bear thereagainst while the other tabs86, although offset downstream from the free edge25, are distant therefrom by distances which are less than the longitudinal dimension of the hoop81between its front faces84and85such that the outside peripheral face83of the hoop81is engaged in full or in part, depending on the zone thereof under consideration, against the entire circumferential dimension of the inside of the ferrule5against the face23thereof. With the hoop81in this state of radial contraction as shown inFIG. 13, the ring4is still in its rest state.

Then, as shown inFIG. 13, a mandrel81is forced longitudinally in the direction opposite to the direction13into the hoop81as engaged in the ferrule5of the ring4. The mandrel88is defined going away from the axis9by an outside peripheral face89that is circularly frustoconical about said axis and that converges in the direction opposite to the direction13between a minimum diameter that is smaller than the diameter then presented by the inside peripheral face82of the hoop81, which diameter can easily be deduced by the person skilled in the art from the diameter of the inside peripheral face23of the ferrule5given the thickness of the hoop81between its inside and outside peripheral faces82and83, and a maximum diameter that is not less than the diameter presented by the inside peripheral face82of the hoop81when in the rest state.

The person skilled in the art will readily understand that this coaxial insertion of the mandrel88into the hoop81and thus into the ferrule5of the ring4causes the diameter of the inside peripheral face82of the hoop81to expand progressively, consequently causing the diameter both of its outside peripheral face83and of the inside peripheral face23of the ferrule5to expand, thus expanding the ferrule both radially and circumferentially.

The mandrel88continues to be inserted coaxially in the direction opposite to the direction13into the hoop81while it is itself received inside the ferrule5until the inside and outside peripheral faces82and83have returned to the diameter they present when at rest, and this is accompanied by the end faces87sliding over each other until they are again pressed flat one against the other, and the hoop81as a whole has returned to its rest configuration. At this point, all of the tabs86are pressed in the direction opposite to the direction13against the free edge25of the ferrule5, as shown inFIG. 14, and the ring4and the tool80as inserted in this ferrule5temporarily constitute an assembly90which is stabilized by the end faces87bearing against each other circumferentially under the effect of the radial pressure applied by the ferrule5to the hoop81, it then being possible to extract the mandrel88in the direction13.

Given the diameter then presented by the inside peripheral face82of the hoop81, the assembly90can be engaged in the direction13on the annular end3of the cylinder2and on the sealing gasket or film18, including its bulge77, quite freely until the limit position is reached in which the annulus34bears via its face35in the direction13against the front face11of the annular end3of the cylinder2, via the rim, if any, of the sealing gasket or film18, which corresponds to the state shown in FIG.15.

Then, by applying thrust or shocks in the direction13to the tabs86(which tabs extend radially far enough to project from the outside peripheral face24of the ferrule5) it is possible to extract the hoop81from the free edge25while keeping the ring in the above-mentioned limit position insofar as the annulus34is kept bearing via its face35against the front face11, via the rim, if any, of the sealing gasket or film18so as to prevent the ring4from moving together with the tool80relative to the cylinder2.

As soon as the upstream front face85of the hoop81escapes from the ferrule5, the ferrule contracts elastically to press its inside peripheral face23against the outside peripheral face12of the annular end3of the cylinder2and against the sealing gasket or film18whose bulge77gives rise to a localized increase in pressure in a continuous ring causing the groove79to be formed in the inside peripheral face23of the ferrule5, preferably by plastic deformation of the ferrule5.

In order to make it easier to extract the tool80from the ferrule5, the longitudinal distance between the shoulder14of the cylinder2and its front face11, or the upstream limit of the rim, if any, of the sealing gasket or film18on said front face11is greater than the longitudinal distance between the free edge25of the ferrule5and the face35of the annulus34by an amount greater than the longitudinal dimension of the hoop81between its upstream front face85and the downstream limit of the tabs86fixed to its downstream front face84so that during extraction the tool80does not come into abutment the shoulder14before it has been fully disengaged from the ferrule5.

Thereafter, the hoop81can be opened by applying traction in a circumferential direction on opposite sides of its split between the faces87so as to open up the split and enable the tool80to be removed either by sliding it in the direction13over the outside peripheral face15of the cylinder2or in the direction opposite to the direction13over the ring4.

The pipe1is then terminated, as shown inFIG. 16, and the skirt6of the ring4constitutes its female endpiece54into which it is possible subsequently to mount (if this has not already been done) a sealing gasket, e.g.62of the type described with reference toFIGS. 7 and 8, and then subsequently insert coaxially the male endpiece7of the other pipe8, as shown in FIG.17.

Transposing this method of mounting the ring4on the cylinder2in the absence of a sealing gasket or film18, possibly replacing it with at least one sealing ring of plastic material, or in the case of a different shape for the sealing gasket18, comes within the normal competence of a person skilled in the art.

In general, such a person skilled in the art will understand that the present invention can be implemented in a wide variety of ways differing from those described above, in particular by combining the variants described insofar as they are mutually compatible, without that going beyond the ambit of the invention.