FR3085460A1 - PROCESS FOR CLOSING THE END OF A TUBULAR PART IN AN ELASTICALLY STRETCHABLE MATERIAL AND FOR END-TO-END ASSEMBLY OF AT LEAST TWO SUCH TUBULAR PARTS - Google Patents

Abstract

This process comprises the following stages: - forced engagement in the first tubular part (1) of a first deformation part (2) having a periphery of the same shape as the cross section of the tubular part (1) but having a larger dimension to this cross section, so that this engagement achieves a stretching of the material of the tubular part (1), up to a location of the tubular part (1) located back from the end to be assembled of the part, so that said stretching forms, by elastic return of the material of the tubular part (1), a flap (4) of a portion of this end towards the inside of the tubular part (1); - forced engagement in at least a second tubular part (10) of a second deformation part (5) in order to form a second identical assembly flap (14), and - production of a sealed connection of the first flap (4 ) and from the second flap (14) to a transverse piece (3) of closure / assembly.

Description

The present invention relates to a method of closing the end of a tubular part made of an elastically deformable material and of butt-joining of at least two of such tubular parts.

The tubular part or parts in question may in particular be any type of hollow tubular part of an inflatable structure, in particular the tubes of a boat such as a kayak, or the inflatable structure of a tent or an airlock. tent, or any type of 3D volume; the elastically deformable material in question is that of which such inflatable structures are commonly made, in particular a film of synthetic material, in particular covered with a textile cover or with a fabric coated with a thermoplastic product. This or these tubular parts can have any type of shape and cross section, in particular a circular cross section.

Inflatable structures made up of end-to-end assembled tubes are widespread, especially in the case of inflatable kayaks or other similar watercraft (canoes, inflatable canoes, pleasure craft tenders) or bulk structures (tent, airlock, frame, etc.).

A rod of such an inflatable structure is produced by making a flat piece of flexible material which is cut to the desired dimensions, then two opposite edges of which are assembled to form the rod and whose ends are closed in order to create the volume capable of retaining a pressurized gas. The tight assembly of the assembled areas of the material can be done by gluing, by sewing and then adding a tape or a sealing polymer, or by welding (high frequency, thermal, pulse, ultrasound, etc. ).

The most common method of making is bonding, although this assembly technique is the most problematic, since it requires little or no investment, whether it is a highly manual activity, suitable to the country with low labor costs and that it authorizes a repositioning of the assembled elements before the glue polymerizes. However, it has drawbacks in terms of respect for the environment and compliance with so-called REACH standards which protect the environment, compliance with standards for working conditions for staff, product reproducibility, aging of assemblies (yellowing, loss adhesion, etc.), of the complete life cycle of the articles (multiplication of components, recycling).

The welding assembly technique avoids these drawbacks.

The simplest method of welding is called peeling; it consists in placing one against the other the two parts to be assembled and then welding these two parts together. The mechanical resistance of a peel weld is however much lower than that of a so-called shear weld.

This mode of shear welding consists of placing the edges to be assembled overlapping each other and then being assembled by welding from one to the other. This shearing process has the drawback, however, of necessarily creating an excess thickness of material at the level of the overlapping zone, which is complex to manage when it is a question of connecting two strands together. Indeed, it is well known that the excess thicknesses of material create leakage gaps in the inflation gas.

The method according to the invention aims to remedy these drawbacks.

To this end, this process comprises the following steps:

- Forced engagement in a first tubular piece of a first deformation piece having a periphery of the same shape as the cross section of the tubular piece but having a dimension greater than this cross section, so that this engagement achieves a stretching of the material of the first tubular part along the transverse periphery of this tubular part; this forced engagement is made up to a location of the first tubular part located set back from the end to be assembled of the part, so that said stretching forms, by elastic return of the material of the tubular part, a first flap d 'a portion of this end towards the inside of the tubular part;

- forced engagement in at least a second tubular part of a second deformation part in order to form a second assembly flap in an identical manner to the way in which the first assembly flap is formed on the first tubular part, and

- Making a tight connection of the first flap and the second flap to a transverse closure / assembly part, having a dimension at least equal to the section of the first tubular part, this transverse part closing the ends to be assembled from the first tubular part and the second tubular part and coming to assemble the first tubular part to the second tubular part.

The method according to the invention thus exploits the tendency towards elastic return towards the inside that an end portion of a tubular part has when a deformation part as mentioned above is forcedly engaged in the tubular part, in order to that this end portion forms an assembly flap to which said transverse part can be linked.

This method makes it possible to close the end of a tubular part and to assemble this end to another tubular part in a relatively simple manner to implement, at an economically acceptable cost, and which remedies in a way general to the drawbacks of the aforementioned prior techniques, in particular which allows a tight connection in shear.

Said tight connection could be made by gluing; glue can thus be deposited on the flaps and / or on the transverse piece, and the deformation pieces can then be used as bearing surfaces to press this transverse piece against these flaps.

Said sealed connection can also be produced by welding; the deformation pieces can then be electrodes applied against the transverse closure piece, in line with the flaps.

The transverse closure / assembly part can be devoid of any passage through it, in order to constitute if necessary a watertight partition between the two tubular parts. It can also include at least one such passage if it is necessary to make a fluid communication between the two tubular parts.

Said second tubular part can be a single second tubular part, having a section identical or close to that of said first tubular part; in this case, the realization of the sealed connection comprises the fact of simultaneously assembling the first flap and the second flap to said transverse part.

Alternatively, a plurality of said second tubular parts can be assembled with said first tubular part, in which case these second tubular parts each have a section smaller than that of the first tubular part; in this case, the realization of the sealed connection comprises the fact of assembling the transverse part to the first flap and then assembling the second flaps of the second tubular parts to the transverse part.

According to one possibility, the end edges to be assembled of said first tubular part and / or of said second tubular part (s) are not perpendicular to a longitudinal axis of the first tubular part or to a longitudinal axis of the second part (s) tubular, respectively; the method then comprises the steps consisting:

- Cutting these end edges not perpendicular to the longitudinal axis of the tubular parts, at angles complementary to said first tubular part to each second tubular part; and

- Assembling said first tubular part to at least one said second tubular part, in the extension of one another, the transverse closure / assembly part being thus oblique with respect to the longitudinal axes of these tubular parts.

Such an assembly makes it possible to increase the surface of the transverse closure part, which is then oblique.

In this same case of end edges to be assembled which are not perpendicular to the longitudinal axis of the tubular parts, the method according to the invention may comprise the step consisting in assembling a said first tubular part to at least one said second tubular part of such that the longitudinal axis of said first tubular part makes an angle different from 180 ° with respect to the longitudinal axis of one or more said second tubular parts.

The assembly configuration implemented by the method according to the invention makes it possible to easily carry out such an assembly of tubular parts forming between them such an angle different from 180 °.

The invention will be clearly understood, and other advantages and characteristics thereof will appear, with reference to the appended schematic drawing, which represents, by way of nonlimiting examples, several forms of implementation of the process concerned.

FIG. 1 is a side view of a first tubular part, one end of which is to be closed and assembled to a second tubular part, and of a welding electrode, the electrode being placed outside the tubular part, on the side of this tubular piece opposite the end to be closed;

FIG. 2 is a view of the tubular part and of the electrode similar to FIG. 1, after the electrode has been forcefully inserted into the tubular part, to a position slightly recessed from the end to to close ; this figure also shows, also seen from the side, a transverse piece for closing / assembling said end of the tubular piece;

FIG. 3 is a view of the tubular part, of the electrode and of the transverse part similar to FIG. 2, and of a second tubular part containing a second welding electrode inserted in it, this second tubular part and this second electrode being in all points similar to the first tubular part and to the first electrode;

FIG. 4 is a view of the tubular parts, of the electrodes and of the transverse part similar to FIG. 3, after simultaneous assembly of one end of said second tubular part with the transverse part and this transverse part with the first tubular part;

Figure 5 is a side view of two said second tubular parts, of smaller diameter, connected to said transverse part;

FIG. 5A is a view similar to FIG. 5 of another implementation;

Figure 6 is a side view of a first tubular piece with end edge cut at an angle and a second tubular piece with end edge cut at an angle whose inclination is complementary to that of the end edge of the first tubular part, the two tubular parts being assembled simultaneously to one another by means of a transverse part as mentioned above, extending obliquely;

Figure 7 is a view of a said first tubular part assembled by the same method to a said second tubular part so that the two tubular parts form between them an angle different from 180 °; and FIG. 8 is a view of a tubular part and of an electrode similar to FIG. 1, while the tubular part is only partially formed tubularly at one end of this part to be closed and assemble to another tubular part.

FIG. 1 represents a first tubular part 1 in particular intended to constitute a structural element of the rod type of an inflatable boat such as a kayak, a canoe or the like, or a frame of 3D volume such as a tent or a airlock in such a volume, etc.). This tubular part 1 is made of a synthetic material commonly used in this type of application, namely a plastic film which can be welded in particular by high frequencies and which is slightly stretchy elastically in its plane, therefore in particular when the tubular part 1 is made up, around the edge of this room.

The tubular part 1 can have all types of cross sections but is in particular, most commonly, of circular cross section.

The tubular part 1 has a longitudinal end 1A intended to be connected to a second tubular part 10 and a longitudinal end 1B opposite the end 1A.

The welding electrode 2 shown in FIG. 1 has a cross section of the same shape as that of the tubular part 1, therefore in particular of circular cross section, but has a dimension greater than that of the tubular part 1, for example greater 5% in diameter. This electrode 2 is forcibly engaged inside the tubular part 1, either, while the tube is formed in its tubular form, by the end 1B if the elastic deformability of the material constituting the part 1 allows such introduction and sliding of the electrode 2 forcibly to the position shown in Figure 2, in which it is placed slightly back from the edge of the end 1A.

Alternatively, if the elastic deformability of the material constituting the part 1 does not allow such introduction and such sliding, and as can be seen in FIG. 8, the part 1 may only be partially formed tubularly at the level of the end 1A, so that the electrode 2 can be engaged in the part 1 in a position slightly set back from this end 1A.

In this position, the circumferential stretching of the material constituting the tubular part 1 causes an end portion of the part 1 to tend, by elastic return of this material, to fall back radially towards the interior of the part 1, and that this end portion thus forms a circumferential flap 4.

The transverse part 3 is intended to close the end 1A of the tubular part 1 and of the corresponding end of the second tubular part 10 and to assemble these two ends. It may have the shape of a disc whose diameter is adapted to the section of the tubular part 1, so that this transverse part 3 is able to come into application against the flap 4.

The counter-electrode 5 is dimensioned with respect to the section of the second tubular part 10, in the same way as the electrode 2 is dimensioned with respect to the tubular part 1, so that the engagement of this counter-electrode 5 inside the part 10 realizes the arrangement of a flap 14 as described previously; the counter electrode 5 is then used to simultaneously apply the flap 14 against the transverse part 3 and the transverse part 3 against the flap 4 in order to simultaneously weld the transverse part 3 to the flaps 4 and 14.

Once the tubular parts 1 and 10 are assembled together, as visible in FIG. 4, the electrodes 2 and 5 are removed from these parts 1.10 by sliding inside the respective parts. In the event of insufficient elasticity of the materials constituting the tubular parts 1 and 10, the electrodes 2 and 5 may have a removable structure allowing these electrodes 2 and 5 to be dismountable in the parts 1 and 10 so that they can be extracted from the latter .

FIG. 5 shows that two second tubular pieces 10 of smaller diameter than the piece 1, or more than two of these pieces 10, can be assembled to the same tubular piece 1, also by fitting a flap in them by means of electrodes of appropriate diameters, then by welding these flaps to the transverse part 3. In this case, the transverse part 3 is generally first welded to the flap 4 then the tubular parts 10 are welded to this transverse part 3.

The tubular parts 1, 10 and 10 can also be welded and assembled simultaneously as visible in FIG. 5 As an annular counter-electrode 5A, the outside diameter of which corresponds to the perimeter of the tubular part 1, and the interior space of which is dimensioned for allowing the pieces 10 to pass is used around these pieces 10. This counter-electrode 5A is shown in section in FIG. 5A.

FIG. 6 shows that two tubular parts 1 and 10 may have end edges cut at angles not perpendicular to the longitudinal direction of these tubular parts 1, 10, and which are arranged at angles complementary to a part 1, 10 to another. In such a case, the transverse part 3 has the shape of an ellipse and is connected obliquely to the first tubular part 1 and then to the second tubular part 10, in the same manner as described above.

Figure 7 shows that two tubular parts 1 and 10 can be assembled other than in the longitudinal extension of one another, and therefore so as to form between them an angle different from 180 °. The angulation between the two parts is obtained simply by cutting the end edges of the parts 1, 10 at the appropriate angles to form this angle.

The method according to the invention thus exploits the tendency for elastic return towards the inside which has an end portion of a tubular part when an electrode / counter-electrode 2, 5, or other deformation part of appropriate section , is forcibly engaged in the tubular part, so that this end portion forms an assembly flap to which said transverse part can be connected. This method allows a closure of the end of the tubular part to be relatively simple to implement, at an economically acceptable cost, and generally remedies the drawbacks of prior homologous techniques.

Claims (9)

1. Method for closing the end of a tubular part (1) in an elastically stretchable material around the periphery of the tubular part (1) and for end-to-end assembly of at least two of such tubular parts (1, 10), characterized in that it comprises the following steps: - Forced engagement in a first tubular part (1) of a first deformation part (2) having a periphery of the same shape as the cross section of the tubular part (1) but having a dimension greater than this cross section, so that this engagement performs a stretching of the material of the tubular part (1) along the transverse periphery of this tubular part (1); this forced engagement is made up to a location of the tubular part (1) located back from the end to be assembled of the part, so that said stretching forms, by elastic return of the material of the tubular part (1) , a flap (4) of a portion of this end towards the inside of the tubular part (1); - forced engagement in at least a second tubular part (10) of a second deformation part (5) in order to form a second assembly flap (14) in the same way as the first flap (4) is formed assembly on the first tubular part (1), and - Making a sealed connection of the first flap (4) and the second flap (14) to a transverse piece (3) of closure / assembly having a dimension at least equal to the section of the first tubular piece (1), this transverse part (3) closing the ends to be assembled of the first tubular part (1) and the second tubular part (10) and coming to assemble the first tubular part (1) to the second tubular part (10). 2. Method according to claim 1, characterized in that said sealed connection is produced by bonding and in that the method comprises the following steps: - deposit of glue on the flaps (4, 14) and / or on the transverse part (3), and - Use of the deformation pieces (2, 5) as bearing surfaces for pressing this transverse piece (3) against these flaps (4, 14). 3. Method according to claim 1, characterized in that said sealed connection is produced by welding and in that it comprises the following steps: - provide the deformation parts in the form of electrodes (2, 5), and - apply the electrodes (2, 5) against the transverse piece (3) of closure, in line with the flaps (4, 14). 4. Method according to one of claims 1 to 3, characterized in that the transverse part (3) of closure / assembly is devoid of any passage through it. 5. Method according to one of claims 1 to 3, characterized in that the transverse part (3) of closure / assembly comprises at least one passage through it. 6. Method according to one of claims 1 to 5, characterized in that said second tubular part is a single second tubular part, having a section identical or close to that of said first tubular part, and in that the realization of the tight connection comprises the fact of simultaneously assembling the first flap (4) and the second flap (14) to said transverse part (3). 7. Method according to one of claims 1 to 5, characterized in that a plurality of said second tubular parts (10) is assembled to said first tubular part (1), in that these second tubular parts (10) have each a section smaller than that of the first tubular part (1), and in that the production of the sealed connection comprises the fact of assembling the transverse part (3) to the first flap (4) and then assembling the second flaps (14) of the second tubular parts (10) to the transverse part (3), or comprises the fact of simultaneously assembling the transverse part (3) to the first flap (4) and the flaps of the second tubular parts (10) to the transverse part (3) if a counter-electrode corresponding to the perimeter of the tubular part 1, and hollowed out in its center to allow the parts 10 to pass, is used around these parts 10. 8. Method according to one of claims 1 to 7, characterized in that it comprises the stages consisting: - cutting the end edges to be joined of said first tubular part (1) and / or said second tubular part (s) (10) at angles complementary to said first tubular part (1) to each second tubular part (10 ); and 5 - to assemble said first tubular part (1) to at least one said second tubular part (10), in the extension of one another, the transverse part (3) of closure / assembly thus being oblique to the longitudinal axes of these tubular parts (1, 10). 9. Method according to one of claims 1 to 7, characterized in that it comprises the steps consisting: - to cut the end edges to be assembled of said first tubular part (1) and / or said second tubular part (s) (10) not perpendicular to a longitudinal axis of the first tubular part (1) or to a longitudinal axis of the second tubular part (s) (10), respectively; and 15 - assembling said first tubular part (1) to at least one said second tubular part (10) so that said first tubular part (1) makes an angle different from 180 ° with respect to one or more said second parts (10).