ITRA20080030A1 - JOINT FOR CORRUGATED TUBES IN PLASTIC MATTER CONSISTING OF A SLEEVE OR EXTERNAL GLASS AND A SEALING GASKET, BOTH OF THEM PREFERABLY INJECTED IN THE SAME FORMING PROCESS. - Google Patents

Description

with one or two walls, especially for traditional plastics containing polyvinyl chloride (PVC), polyethylene and polypropylene, which combine good characteristics of resistance to internal pressure and external stresses, with considerable lightness and consequently good savings 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 relevant 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, sometimes blunt, of the next pipe, forming a joint that takes the name of "socket joint" from it; in it the seal is normally made with the addition of a rubber gasket ring.

These problems, which occur in the phases of hot plastic deformation, mainly derive from the alteration of the shape of the ribs and the presence of a plastic memory in the polyolefins, which tends to return the material to its original position.

They were overcome with the invention cited in patent application no. RA2007A000015 filed on 02/03/2007 by the same firm IPM di Argnani Claudio & C snc; in it the outer sleeve of the joint is obtained by injection during the forming process, so that it can adhere and weld with the edge of the pipe, possibly prepared for the purpose, for example by milling. In the same sleeve, with the same injection process, the seat of a sealing gasket is also obtained, arranged circumferentially in the appropriate position, and having the shape and dimensions suitable for those of the gasket itself, which will be subsequently mounted.

In this way the shape of the glass remains stable and the ribs

they have no opportunity to deform.

In the above procedure and joint, however, the problem of the subsequent assembly of the gasket remains, which presents various and known difficulties: the possible forgetting of its insertion or in any case an incorrect insertion, such as sense of work and position, making the sealing of the joint, the practical difficulties of the introduction operation, especially for large diameters, because considerable manual efforts are required, and with the need for appropriate mechanical tools, the possibility of dirt accumulation during handling and storage in the spaces provided for the gasket itself.

To obviate the above problems, while retaining the advantages of which the solution brings (stability of the sleeve and of the ribs), the present invention proposes an improved and innovative solution: in fact it provides for inserting the sealing gasket, in the appropriate and alternative solutions of which are subsequently proposed, preferably already during the forming process, thus using the same mold or part of it by means of an injection process of the same type but subsequent as an executive step to that of the sleeve.

In practice, during a single forming process, the outer sleeve or socket is produced, with the sealing gasket <,> inserted and positioned, eliminating the aforementioned drawbacks: in particular the difficulty of insertion, an incorrect insertion, and an oversight; moreover, a single process reduces costs, compared to those of subsequent processes over time, sleeve, due to an injection of the gasket in a subsequent process.

Since the forming process allows it, it is possible to use materials suitable for carrying out the sealing effect correctly and optimally, such as various types of rubber; likewise the process allows to form gaskets of various shapes and suitable to correctly perform the sealing function.

It is also possible to produce gaskets of axial length such as to surely affect at least one outer ring of the pipe corrugation, the latter being the suitable surface, given the cylindrical shape, to make the joint seal.

However, it is possible, as a constructive alternative but falling within the same inventive scope, to produce gaskets of any length, as long as there is in the joint a device for correct positioning of the two parts coupled therein, i.e. the outer sleeve, and therefore the gasket, and the normal end of the joint. corrugated pipe: this is to make the position coincide

sealing members of the gasket with at least one cylindrical outer corruption ring; for this purpose it is particularly suitable a check tooth, positioned at the end of the outer sleeve, of form

and suitable size.

In practice, the present invention claims both a type of joint, with an external sleeve and sealing gasket both injected, and at the same time a predutive system, ensuring that the sleeve and gasket are ineffective., Inside the same forming process, using globally, to the same equipment, albeit in later stages.

The materials currently proposed for the injection of the sleeve are common plastics, in particular polyolefins (polypropylene and polyethylene). These and further characteristics and advantages of the present invention are more evident from the following detailed description of an embodiment, illustrated by way of non-limiting example.

Fig. I of Tav, 1 shows an overall axial section of the joint of a double-walled corrugated pipe, made according to the principles of the present invention.

Fig. 2 of Tab, 1 represents an enlargement of Fig. 1, corresponding in particular to the area of the sealing gasket.

Fig. 3 of Tab, 2 represents an axial section of the outer sleeve or socket only, represented in Fig. I.

Fig. 4 of Tab, 2 represents an enlargement of Fig. 3, corresponding in particular to the area of the sealing gasket.

Fig. 5 of Table 2 represents an axonometric view of the outer sleeve or socket of Fig. 3.

The double-walled tube (1) is fixed at its cut or milled end edge (2) to the injected outer sleeve (3), by welding resulting from the injection process.

This sleeve, of approximately cylindrical shape and adequate length, preferably has a conical inlet (4) at the free end, to facilitate the insertion of the reinforcement ribs (5), and an annular seat open towards the inside ( 6), to contain the seal gasket (7); the latter is in turn injected into the seat (6).

In the assembled joint, the smooth end of the tube (8) must have at least one outer ring (9) of the corrugation corresponding with the sealing elements (10) of the gasket (7); this is obtained in Fig. 1 and Fig. 3 with a sufficient length L1 of the gasket itself.

Figures 1, 2, 3 and 5 refer to a particular type of corrugated pipe; however, the fact that (the shape and dimensions of the ribs or corrugations are different from those indicated, or that the glass has a shape and size different from those shown in the figure, for example with the absence of the initial invitation cone, does not constitute an inventive limit.

The injected gasket can be of a type other than that indicated with numbering (7). both for the sealing elements and for the external shape; the materials used may also be different from each other, as long as they are suitable for the required purposes, mainly for sealing purposes.

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 preventive removal of one or more external ribs of the pipe with a milling process.

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

Claims (10)

CLAIMS 1) Joint for corrugated pipes with one or two walls in plastic material preferably polyolefin, comprising an external sleeve injected in plastic material, welded to the normal pipe, and a sealing gasket, also injected inside a special annular seat open on the internal cylindrical surface of the joint. 2) Joint according to claim 1), in which the outer sleeve and the sealing gasket are injected within the same forming process, using the same molds to varying degrees. 3) Joint according to claims 1) or 2), 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. 4) Joint according to claims 1) or 2) or 3), 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 coupled pipe end, regardless of the relative positioning between the two internal and external components of the socket joint. 5) Joint according to claims 1) or 2) or 3), 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 a positioning and fixing device axial between the outer sleeve and the coupled end of the pipe, such that the internal sealing elements of the gasket correspond to the surface of an outer ring of a rib or corrugation of the pipe. 6) Coupling according to claims 1) or 2) or 3) or 4) or 5), in which the sealing elements of the gasket are of the lip type. 7) Joint according to claims 1) or 2) or 3) or 4) or 5) or 6), in which the injected sleeve has a series of external reinforcing ribs. 8) Joint according to claims 1) or 2) or 3) or 4) or 5) or 6) or 7), in which the corrugated pipe is of the double-walled type, with smooth cylindrical internal wall and corrugated external wall. 9) Joint according to claims 1) or 2) or 3) or 4) or 5) or 6) or 7) or 8), in which the coaxiality between the two components of the socket joint, respectively external or sleeve and internal or the 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 the sleeve and the normal pipe, such as to make the sleeve itself flexible and orientable. 10) Joint according to the preceding claims and substantially as illustrated in the attached drawings and for the specified purposes.