ITRA20070015A1 - MAKING SYSTEM OF CORRUGATED TUBES IN PLASTIC MATERIALS WITH INJECTED EXTERNAL SLEEVE AND SEAT HOLDER GASKET - Google Patents

Description

"SOCKET SYSTEM OF CORRUGATED PIPES IN PLASTIC MATERIAL WITH INJECTED EXTERNAL SLEEVE AND EQUIPPED WITH SEAL HOLDER SEAT

SUMMARY

The invention relates to a belling system for corrugated pipes with one or two walls in plastic material, preferably of the polyolefin type, consisting for the internal part in an end section of normal pipe, and for the external part in an injected sleeve. in plastic material so as to adhere and weld with an edge of the pipe, possibly milled: this sleeve also has an annular seat open on the intented surface, suitable for containing a sealing gasket, which in a first solution has an axial width such that internal elements interact with at least one outer ring of a corrugation of the coupled pipe end: in a second solution, although having any width, its axial positioning on an outer ring is guaranteed by the position of the gasket seat and by the length and configuration of the sleeve external, preferably equipped with a matching tooth at the end.

DESCRIPTION

In the current technique the use of corrugated pipes with one or two walls is becoming more and more widespread, especially for traditional plastics such as polyvinyl chloride (PVC), polyethylene and polypropylene, which combine good characteristics of resistance to internal pressure and external stresses, to a considerable lightness and consequently to a good saving of material, compared to traditional solid-wall pipes.

However, problems arise in forming the "socket" since the latter is the term used in the sector, including the relative legislation, to call the end of the tube shaped like an external sleeve, which is coupled in the formation of the joint, with the normal end , usually chamfered, of the next pipe, forming a joint that takes the name of "socket joint" from it; in it the seal can be made by gluing the two male and female ends or more frequently with a sealing ring Rubber.

The above problems occur in the formation of the outer sleeve by heating and hot plastic deformation since in the expansion operation the ribs are deformed and in particular for the polyolefins there is a plastic memory that tends to return the material towards the position original innermost: even the solution of positioning the gasket between two successive external ribs of the pipe, at the end that is coupled, while being functional in making the joint, since the sleeve can be smooth, has the drawback of damaging the gasket itself in the transport and rubbing of the pipe in earth or sand, sometimes causing the seal to fail,

To overcome the above problems there is a solution which consists in making a smooth section, already in the corrugation phase which, subsequently cut in half, represents the respectively initial and final areas of the pipe, on which the socket joint is obtained; in fact, one of the two ends is formed as an external sleeve with hot plastic deformation, obtaining in it a circumferential seat where to place the sealing gasket, which therefore rests on the corresponding smooth end of the coupled pipe. This solution has the advantage of positioning the gasket inside the pipe, in a protected position, but at the same time it has the disadvantages of an external sleeve that tends to return to its original position with a smaller diameter, if the plastic materials are of the polyolefin type, and of a length achievable on site with a fixed and non-modifiable pipe for constructional needs of the pipes.

There are also solutions that provide for a stable outer sleeve, while using polyolefin-type plastic materials: in particular, we cite those, protected by an invention patent application, by the same company proposing the present invention, which in a first case provide for the insertion, at the inside of the socket, of a pre-built sleeve of approximately cylindrical shape: in a second case the injection. inside the ribs, previously perforated and corresponding to the area of the bowl, a sufficiently resistant filling material after its solidification: in a third case the injection of a suitable approximately cylindrical shaped sleeve, on the external surface of the bowl, possibly milled to remove the ribs, and formed with hot plastic deformation.

However, all these solutions present constructional difficulties and high costs, and also provide for the execution of approximately cylindrical and smooth sleeves, the gasket being provided between two external ribs to the coupled tube, with the possibility of the aforementioned drawbacks.

The present invention proposes a different, improved and innovative solution to solve the problem of the joints of the socket-type corrugated pipes: in fact it provides for the realization of an external sleeve, suitably shaped with possible reinforcement ribs, which is injected at a end edge of the corrugated tube; the latter was possibly milled on the outside for a short distance, removing one or more ribs, to allow adhesion and welding between 11 rubo and the sleeve itself.

In the same sleeve, an annular seat of suitable shape is obtained, which faces and is open on its internal surface, suitable for containing the seal gasket of the joint.

Since the problem is that of making the internal sealing surface of the gasket correspond with the external one, in the form of a ring, of a corrugation. belonging to the section of normal pipe, which represents the internal component of the overall joint, two equivalent solutions are proposed in the invention from the inventive and functional point of view: a first solution provides for the use of a gasket of width, in the axial direction of the pipe, such as that its internal sealing systems (with lips or teeth or other) can act on the surface of at least one outer ring of the corrugated pipe, whatever the relative position between the internal and external components of the joint.

A second solution instead provides for the use of a gasket of any axial width, therefore without any constraint in this regard, but at the same time also provides for the realization of a reciprocal positioning system between the external parts or sleeve and the internal part or end of the pipe, of the joint itself; this positioning system must in any case match the internal sealing surface of the gasket with that of an outer ring of the corrugated pipe, and therefore with the extrados of a circumferential corrugation; it is preferably made by providing the outer sleeve of a matching tooth at its end, such that the useful cylindrical coupling length, between the above tooth and the beginning of the conical surface for connection to the tube, corresponds to that of the ribs or corrugations involved in the coupling itself.

The proposed solution therefore has the advantage of an external sleeve that is stable and not affected by the plastic memory of the material, of a gasket housed inside the socket, in a protected position and therefore not exposed to assembly damage, and of the possibility of construction of any length of pipe, compatibly with the practical needs of the pipes.

The materials currently proposed for injection are common plastics, such as PVC and polyolefins (polypropylene and polyethylene).

These and further characteristics and advantages of the present invention will become more evident from the following detailed description of an embodiment, illustrated by way of non-limiting example.

Fig. 1 of Tav, 1 shows an axial section of the socket joint of a double-walled corrugated pipe, made with the principles of the present invention, according to the first proposed solution.

Fig. 2 of Table J represents an enlarged detail of the same Fig. I, where the sealing gasket is visible.

Fig. 3 of Tab, 2 represents an axial section of the socket joint of a double-walled corrugated pipe, made with the principles of the present invention, according to the second proposed solution.

The Fig. 4 of Table 2 shows an enlarged detail of the same Fig. 3, where the sealing gasket is visible.

The double-walled pipe (1) is fixed at its end edge (2), after removing an external rib with milling: the external sleeve (3) of Table 1 or (4) of Table 2 is obtained by injection and has an edge superimposed on (2), to which it is therefore welded, fixing itself to the tube (1). This sleeve, of approximately cylindrical shape and adequate length, preferably has a conical inlet (5) at the free end to facilitate the insertion of the reinforcing ribs (6), and an annular seat open towards the inside to contain the sealing gasket.

In Table L corresponding to the first proposed solution, the annular seat (7) has a width L1 such that the gasket contained therein (8) rests on two outer rings (9) of the corrugation. as in the positioning of the figure, or in any case, with a different positioning, on at least one outer ring (9). The useful length L2 of the sleeve is irrelevant and therefore conditioned only by coupling and resistance requirements, and in particular it is independent from that of the corresponding ribs of the normal pipe section (10), which constitutes the internal or male part of the joint.

In Table 2, corresponding to the second solution proposed, the annular seat (13) has any width L3, without any constraint except related to the functionality of the gasket: in particular it can be smaller than that of the space between two successive ribs of the tube.

In order for the gasket (12) to position itself in correspondence with an outer ring (9) of the pipe corrugation, as in Fig. 4, the sleeve (4) must be suitably positioned with respect to the coupled end of the pipe (10), condition which is realized since the length L4, between the beginning of the conical surface (14) connecting the pipe and the sleeve, and the edge of an annular stop tooth (1 1) must be equal to the axial development of a certain predetermined number of ribs, which in the case of Fig, 4 by way of example, is equal to 5. the tooth (11), given its shape, which is connected with an open conical tuck (5), deforms elastically towards the external diameters during the introduction of the tube inside the sleeve, then blocking it at the end of the introduction itself, in the centering position, due to its elastic return in the normal position, corresponding to a smaller diameter than the previous ones

Figures I and 3 refer to a particular type of corrugated tube; however, the fact that the shape and dimensions of the ribs or corrugations are different from those indicated does not constitute an inventive limit, or that the glass has a shape and size different from those shown in the figure, for example with the absence of the initial guiding cone.

The gasket used can be of a different type from the lip ones indicated with the numbers (8) and (12) of the attached figures, both for the sealing elements and for the external shape: the materials used can also be different from each other, provided they are suitable for the required purposes, mainly for sealing purposes. This gasket, if built in advance, can also be inserted in its seat in the already formed outer sleeve, with normal manual or automatic systems; or it can be directly injected into the seat itself, preferably during the steps of forming the aforementioned sleeve.

The positioning system of the sleeve (4) with respect to the end of the normal tube (10) can be of a different type from that indicated in Figs, 3 and 4. for example, it can be constituted by annular teeth of different shape, or by two teeth annular, instead of just one, placed at a suitable distance, and of a shape suitable for locking the sleeve on both sides between two predefined annular ribs (or corrugations) of the end of the pipe; the locking rib could also be a single one, with two annular teeth acting as bilateral abutment.

The junction between the injected sleeve and the end of the normal pipe can be obtained by overlapping and welding the two elements in a more or less wide annular area in the axial direction, preferably requiring a prior removal of one or more external ribs of the pipe with a milling process.

A good coaxial between the two external (sleeve) and internal (tube) components of the socket joint, which improves the coupling and the tightness, can also be favored by making the orientation of the sleeve itself variable, with a bellows system flexible obtained preferably in correspondence with its conical connection area with the normal pipe.

Claims (1)

CLAIMS 1) Belling system for corrugated pipes with one or two walls, in plastic material of the preferably polyolefin type. comprising an external sleeve injected in plastic material, welded to the normal pipe, which has an open annular seat on its internal cylindrical surface, suitable for containing a suitable seal gasket for the joint, 2) System according to claim 1), in which the welded joint between the outer sleeve and the normal pipe is obtained by overlapping the two elements in a more or less wide annular area in the axial direction, preferably requiring the prior removal of one or more external ribs of the tube with a milling process. 3) System according to claims 1) 02), in which the axial width of the gasket and therefore of the relative housing seat is such as to rest with its internal sealing elements on at least one outer ring of a rib or corrugation of the end of coupled pipe, whatever the relative positioning between the two internal and external components of the socket joint. 4) System according to claims 1) or 2), in which the axial width of the gasket and therefore of the relative housing seat is of any type, linked only to functional sealing requirements, provided that there is an axial positioning and fixing device between the outer sleeve and the end of the tube coupled, such that the inner sealing elements of the gasket correspond to the surface of an outer ring of a rib or corrugation of the tube. 5) System according to claims 1) or 2) or 4), in which the device for axial positioning and fixing is made by means of the presence of a suitable annular stop tooth, preferably placed at the end of the sleeve and elastically deformable during its insertion into the coupled tube end; this tooth is furthermore located at an axial distance from the beginning of the conical connecting surface between pipe and sleeve equal to that corresponding to a predetermined number of ribs or corrugations of the pipe itself. 6) System according to claims 1) or 2) ø 3) or 4) or 5), in which the plastic material of the sleeve is the same as that of the pipe, 7) System according to claims 1) or 2) or 3) or 4) or 5), in which the plastic material of the sleeve is different from that of the pipe, but such that it can be welded with it by fusion in a homogeneous way during injection . 8) System according to claims 1) or 2) or 3) or 4) or 5) or 6) or 7), in which the shape, the dimensions and the type of plastic material used for the injection of the outer sleeve are such to withstand the stresses possible during use, 9) System according to claims I) or 2) or 3) or 4) or 3) or 6) 07) or 8), in which the sealing elements of the gasket are of the lip type, I 0) System according to claims 1) or 2) or 3) or 4) or 5) or 6) or 7) ø 8i or 9), in which the gasket materials are of different types as long as they are suitable for the required purposes, mainly sealing ones. 1 1) System according to claims 1) or 2) or 3) or 4) or 5) or 6} or 7) or 8} or 9) or 10), in which the gasket, previously constructed, is inserted in the special seat of the already formed outer sleeve of the socket, with normal manual or automatic systems, 12) System according to claims 1) or 2) or 3) or 4) or 5) or 6) or 7) or 8) or 9) or 10), in which the gasket is directly injected into the appropriate seat of the outer sleeve of the cup, preferably during the phases of forming the latter. 13) System according to claims 1) or 2) or 1) or 4) or 5) or 6) or 7) ø 8) or 9) or 10) or II) or 12), in which the injected sleeve has a series of external reinforcement ribs. 14) System according to claims 1) or 2) ø 3) or 4) or 5) ø 6) or 7) or 8) ø 9) or 10) or 11) or 12) or 13), in which the corrugated pipe it is of the double wall type, with smooth cylindrical internal wall and corrugated external wall. 15) System according to claims 1) or 2) or 3) or 4) or 5) or 6) or 7) or 8) or 9) or 10) or li) © 12) or 13) ø 14), in which the shape of the circular ribs or corrugations of the tubes is of various types. 16) System according to claims 1) ø 2) or 4) ø 6) or 7) ø 8) or 9) ø 10) ø 11) ø 12) or 13) or 14) or 15). in which the axial positioning and fixing device is made with the presence of two suitable annular stop teeth, placed on the internal surface of the outer sleeve, acting as a whole so as to prevent the relative movement of the two components of the joint in each of the two directions, and placed between them at an axial distance equal to that corresponding to a predetermined number of ribs of the tube itself. 17) System according to claims 1) or 2) or 3) or 4) or 5) or 6) or 7) or 8) or 9) or 10) or ll) or 12) or 13) or 14) or 15) u 16), in which the coaxiality between the two components of the socket joint, respectively external or sleeve and internal or coupled end of the pipe, is favored by an elastic bellows device, preferably obtained by shaping the walls in correspondence with the conical connection area between coupling and normal pipe, such as to make the coupling itself flexible and orientable. 18} System according to the preceding claims and substantially as illustrated in the attached drawings and for the specified purposes,