EP3442777A1

EP3442777A1 - Method for producing a reservoir with a closed chamber, equipment for implementing said method and reservoir

Info

Publication number: EP3442777A1
Application number: EP17722090.2A
Authority: EP
Inventors: Pierric Besnard
Original assignee: Iguatech
Current assignee: Iguatech
Priority date: 2016-04-12
Filing date: 2017-04-11
Publication date: 2019-02-20
Also published as: WO2017178749A1; MA43789A; FR3049893B1; FR3049893A1

Abstract

A method for producing a reservoir with a so-called closed chamber from two shells (3) made from synthetic material moulded by injection or compression and each in the form of a hollow body (4) provided with an outer peripheral rim (5), each shell (3) being arranged in a hollow die (6). The chamber of the reservoir has at least one opening (19) for the chamber to communicate with the outside of the chamber and at least one of the dies (6) is provided with a knife (9) at the area where the outer peripheral rim (5) of the shell (3) bears on said die (6), said method comprising a step of heating the outer peripheral rim (5) and the lateral wall delimiting the hollow body (4) adjacent to said rim (5) of each shell (3), a step of bringing the associated shells (3) and dies (6) together with a view to crushing and cutting said outer peripheral rims (5), a step of introducing and keeping a pressurised fluid inside the chamber of the reservoir, a step of draining said chamber of said reservoir and a step of moving the dies (6) apart with a view to demoulding the reservoir.

Description

PROCESS FOR MANUFACTURING A CLOSED SPEED TANK, TOOLING FOR CARRYING OUT SAID METHOD AND TANK

FIELD OF THE INVENTION

The invention relates to a method of manufacturing a closed enclosure reservoir, the tool for implementing said method and the reservoir obtained.

It relates more particularly to a method of manufacturing a plastic tank, including fuel, from at least two shells molded by injection or compression, said shells each having the shape of a hollow body equipped with a rim external device, said shells being positionable against each other by the outer peripheral rim to form the closed chamber of said reservoir, each shell being arranged in a hollow matrix capable of marrying at least one

15 part of the outer shape of the associated shell.

PRIOR ART

Plastic tanks are commonly used in industry and especially in the automobile such as, for example, fuel tanks, windshields tanks or other.

Plastic tanks have many advantages such as weight reduction, greater flexibility in shaping, ability to deform in the event of impact.

For many years, single-layer and multilayer plastic fuel tanks have been used for gasoline or diesel fuel-powered vehicles as well as for hybrid vehicles that combine the use electric motor and a heat engine. Fuel tanks are generally obtained by extrusion blow molding or thermoforming or rotational molding technologies. Plastic fuel tanks of small capacity are sometimes formed of injected shells welded together.

The injected shells have the advantage of being able to integrate functions on their internal and external faces, such as, for example, fastening lugs, fastening clips, ribs, partitions or others. In addition, components such as, for example, pipes, valves or the like can be easily placed inside the tank before the shells are welded.

To prevent fuel leakage, special attention is paid to the robustness of the tank seam. Indeed, the joint plane is solicited during the current use of the vehicle under the effect of vibrations, variations in the pressure in the tank (typically -500 mbar up to +600 mbar for hybrid gasoline vehicles) , variations in temperature, fuel movements, fuel load ... In addition, the joint plane can be subject to shock during a vehicle accident.

Welding the joint plane of a fuel tank consisting of injection molded plastic shells or compression requires shaped forms, commonly called welding sidewalks, on the outer periphery of the tank as illustrated for example in CN204357803.

These sidewalks with a width of about 5 mm have the disadvantage of reducing the capacity of the tank. On the other hand, the control of the quality of the weld is difficult especially for the joint planes having a large developed length or having a tortuous course. Finally, the shapes and rigidity of the joint plane reduce its mechanical strength. PURPOSE AND SUMMARY

An object of the invention is therefore to provide a method of manufacturing a tank whose design allows a good mechanical strength of the joint plane, without impairing the possibility of obtaining a tank without a sidewalk or weld line for optimize, if necessary, the capacity of the tank.

For this purpose, the subject of the invention is a process for manufacturing a so-called enclosed reservoir from at least two synthetic shells molded by injection or compression, said shells each having the shape of a hollow body equipped with an outer peripheral rim, said shells being positionable against each other by their outer peripheral rim to form the closed chamber of said reservoir, each shell being disposed in a hollow matrix capable of marrying at least a part of the outer shape of the associated shell, characterized in that the chamber of the tank formed by the two shells in the positioned state applies one against the other by their outer peripheral rim, having at least one orifice of communicating the enclosure with the outside of the enclosure, and at least one of the matrices being provided, at the level of the support zone of the outer peripheral edge the method comprises a step of heating the outer peripheral rim and the lateral wall defining the hollow body. adjoining said outer peripheral rim of each shell in order to soften the constitutive material of each shell at the heated zones, a step of bringing the shells and associated dies closer together until the knife of one of the dies comes into contact with each other with the other die or a knife carried by the other die for crushing and cutting said outer peripheral rims, a step of introducing and maintaining a fluid under pressure inside the reservoir chamber formed in the close position of the shells, a step of exhausting said chamber of said tank and a step of spacing the dies in view of a mold release. Thanks to the implementation of the process, this results in a return of material towards the inside of the joint plane during the welding of the shells, this return of material allowing an increase in the thickness of the wall of the tank in the area of the joint plane, thus reinforcing the mechanical strength of said joint plane.

In addition, the presence of knife (x) allows to vary at will the size of the sidewalks welding, to remove them without harming the mechanical strength of the joint plane.

Thanks to the pressurization by injection of a fluid under pressure inside the enclosure, this results in an alignment of the walls of the enclosure at the joint plane, this alignment improving the quality and the robustness of the welding of the shells together.

Due to the fact that in the positioned state applies one against the other by their peripheral edge, the dies have at least one communication orifice of the inside of the volume delimited by said matrices with the outside, and that each communication orifice of the interior of the volume delimited by said matrices with the outside may be arranged in concordance with a communication orifice of the tank enclosure with the outside, it results in a pressurization and a fast and efficient exhaust. According to an embodiment of the method, the method comprises an additional step of detaching the material from the outer peripheral rim of the shells arranged, at the level of the assembly zone of the shells together, outside the enclosure of the tank, and connected to the enclosure by the cutting area of said outer peripheral rims resulting from the action of the knife or knives.

This additional step results from the frequent maintenance of a thin blade of material between said knives on at least a portion of the outer periphery of the joint plane. According to one embodiment of the method, during the step of introducing a pressurized fluid into the chamber of the tank, with a view to pressurizing said chamber, the fluid is introduced at a pressure between 0.1 and 50 bar and is selected from the group formed by air, neutral gases, such as nitrogen.

According to one embodiment of the method, the knife of each matrix equipped with a knife extends at least partially inside a reservation formed in the thickness of the outer peripheral edge of the shell associated with said matrix. , in the state positioned in support of the outer peripheral edge of the shell on said matrix.

According to one embodiment of the method, at the beginning of the heating step, the outer peripheral rim of said shells has a solidified surface material and softened in the plastic state and / or viscous core.

The heating step is carried out in this case as an extension of the manufacturing step by injection or compression of the shells.

The invention also relates to a tool for the implementation of a method of the aforementioned type for the manufacture of a closed chamber reservoir from at least two molded shells injection or compression, said shells affecting each the shape of a hollow body equipped with an outer peripheral rim, said shells being positionable and applied against each other by their outer peripheral rim to form the closed chamber of said reservoir, this closed chamber having at least one orifice communicating the enclosure with the outside of the enclosure, said tool comprising two hollow matrices, each matrix being in the form of a cup-shaped part whose cavity is bordered by an outer peripheral edge, said matrices being able to conform each to at least a part of the outer shape of the associated shell, to the arranged state of the associated shell in said matrix a with the rim of the shell overlapping at least partially the outer peripheral edge of the matrix, characterized in that the outer peripheral edge of at least one of the dies is equipped with a suitable knife to come in bearing contact with the outer peripheral edge or with a knife facing the other matrix in the positioned state applies one against the other by their outer peripheral edge of said dies and in that said tooling comprises, in the positioned state applies against each other by their outer peripheral edge of said matrices, at least one communication port of the interior of the volume defined by said matrices with the outside.

According to one embodiment of the tooling, the knife of at least one of the dies surrounds in the manner of a continuous or discontinuous wall the cavity of the matrix. According to one embodiment of the tooling, the knife of at least one of the dies is disposed, over at least a part of its length, spaced from the inner circumferential portion of the outer peripheral edge adjacent the cavity of the die .

According to one embodiment of the tooling, the knife of at least one of the dies is separated from the outer circumferential portion of the outer peripheral edge of the die by at least one recess of said outer peripheral edge adapted to form a housing of receiving the material in excess of the outer peripheral edges of the shells after cutting by the knife or knives. According to one embodiment of the tooling, the knife of at least one of the dies is disposed at the inner circumferential portion of the outer peripheral edge adjacent the cavity of the die. This results in the possibility of having a tank free of sidewalks or welds.

Alternatively, the knife of at least one of the dies is disposed at least locally spaced from the inner circumferential portion of the outer peripheral edge adjacent the cavity of the matrix.

According to one embodiment of the tooling, the cavity of at least one of the dies is isolated from the outer circumferential portion of the peripheral edge external of said matrix by at least one fixed or movable flange projecting from said outer peripheral edge, this flange being adapted to form, with the facing matrix or a fixed or movable flange of the opposite matrix, in the close position of said matrices, a barrier of said cavity with the outside. This barrier which doubles the wall formed by the knives promotes the return of material towards the inside of the joint plane during the welding of the shells. A development of this barrier can be carried out empirically for the optimization of the thickness of the wall of the tank in the area of the joint plane. The subject of the invention is also a so-called closed-containment reservoir comprising at least two injection-molded or compression-molded shells weldable at their joint plane, characterized in that, in the welded state of the two shells, the tank present internally, in the region of the joint plane, a corrugated profile with the longitudinal axis of each wave developing substantially parallel to the joint plane in the manner of a bead developing on the inner periphery of the enclosure.

According to one embodiment of the reservoir, the reservoir is at least partially free, outside the reservoir, at the level of the joint plane, sidewalk or weld. According to one embodiment of the reservoir, said shells each affect, before joining by welding, the shape of a hollow body equipped with an outer peripheral rim, said shells being positionable against each other by their peripheral rim external to form the closed chamber of said tank, the tank having, in the position of the shells applied against each other by their outer peripheral rim, at least one communication port of the enclosure with the outside .

According to one embodiment of the reservoir, each shell has, on at least a portion of the length of the outer peripheral rim, a thickness of the outer peripheral rim greater than the thickness of the delimiting side wall of the hollow body adjacent said rim. Thanks to this extra thickness of while the material at the surface of the rim is solidified, the core material of the rim is softened in the plastic and / or viscous state so that the heating step can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood on reading the following description of exemplary embodiments, with reference to the appended drawings in which:

- Figure 1A shows a perspective view of a so-called closed enclosure tank according to the invention devoid of sidewalk or edging. - Figure 1 B shows a perspective view of a so-called closed enclosure tank according to the invention provided locally with a sidewalk forming tab.

- Figure 2 shows a schematic sectional view of the tooling and shells during the step of heating parts of the shells.

- Figure 3 shows a schematic sectional view of the tooling and shells during the pressurizing step of the chamber of the tank.

- Figure 4 shows a schematic sectional view of the reservoir at the end of the assembly by welding.

- Figure 5 shows a schematic sectional view of the tank after the additional step of detaching the tank from the material of the outer peripheral edge of the shells.

FIG. 6 represents a partial diagrammatic sectional view of the associated dies and shells, in one embodiment in which the knife of each of the dies is arranged spaced apart from the inner circumferential portion of the outer peripheral edge adjacent to the cavity of the die. FIG. 7A represents a partial diagrammatic sectional view of the matrices and associated shells, in one embodiment in which the area adjacent the cutting edge of the knives is rounded.

FIG. 7B represents a partial view of the reservoir, at the level of the tank joint plane, in the case of an embodiment according to FIG. 7A. FIG. 8 is a diagrammatic sectional view of the associated dies and shells, in one embodiment in which one of the inlet or outlet ports of fluid under pressure is formed in the joint plane of the dies and shells. associated.

FIG. 9 is a diagrammatic sectional view of the associated dies and shells, in one embodiment in which one of the dies is at least partially devoid of knife.

FIGS. 10A and 10B each represent a schematic sectional view of the associated matrices and shells, in one embodiment in which a so-called sealing barrier of the die cavity with the outside is provided, said barrier being in position open (FIG. 10A) and closed (FIG. 10B).

- Figure 1 1 shows a schematic sectional view of the associated dies and shells, in another embodiment of a so-called sealing barrier of the die cavity with the outside. - Figure 12 shows a schematic sectional view of a tank with a connecting pillar.

- Figure 13 shows a partial schematic sectional view of the associated dies and shells, in one embodiment in which the dies are provided with knives at the weld zone of the connecting pillar. - Figure 14 shows a schematic partial sectional view of an associated matrix and shell before heating, in the case of an embodiment according to Figure 13.

- Figure 15 shows a partial schematic sectional view of the associated dies and shells, in an embodiment in which the dies are not provided with knives at the weld zone of the connecting pillar.

FIG. 16 represents a schematic partial sectional view of an associated matrix and shell before heating, in the case of an embodiment according to FIG. 15. FIG. 17 represents a partial schematic sectional view of the matrices and associated shells, in an embodiment in which, after welding, the connecting pillar comprises, in the weld zone of the pillar, a chamber provided with an orifice.

FIG. 18 represents a schematic partial sectional view of a matrix and associated shell before heating, in the case of an embodiment according to FIG. 17.

As mentioned above, the invention relates to a method of manufacturing a reservoir 1 at least from two shells 3 molded by injection or compression. This tank 1 can be a fuel tank or other.

It should be noted that by injection is meant indifferently simple injection, compression injection, sequential injection, co-injection, molding injection or gas injection.

This tank 1 is said closed chamber, as opposed to an open tank on top, also called open tank. Of course, the tank 1 is provided with at least one filling and / or emptying and / or venting and / or degassing orifice of said tank, not shown.

It should be noted that although the figures here present a reservoir with similar upper and lower shells, their shapes can be very different. Similarly, although the figures have a simple course of the joint plane, its course can be tortuous.

Each shell 3 of the tank 1 is a piece of synthetic material, in particular plastic. By "plastic" is meant any thermoplastic material, including thermoplastic elastomers, comprising at least one thermoplastic polymer. The polymers include both homopolymers and copolymers.

Without limitation, it is possible to use polyolefins, polyoxymethylenes, polymers of vinyl alcohol (PVOH and EVOH), polyamides, polyesters, polyketones, fluorinated polymers, polyacrylonitriles, polyvinylidene halides ( PVDF, PVDC), liquid crystal polymers. It is possible to use a mixture of polymers and a mixture of polymers with natural and / or organic and / or inorganic fillers such as, for example, but not limited to: glass, carbon and talc. The fillers may be in the form of fibers, flakes, beads, powder or the like. It is also possible to use multilayer structures consisting of stacked layers comprising at least one thermoplastic polymer.

The shells 3 of the tank 1 may be made of different plastics or different grades. In this case, these materials are compatible for the welding of the shells. The shells 3 may also consist of virgin material and / or recycled.

High density polyethylene (HDPE) is widely used, it gives good results. To waterproof the fuel tank, it may be subject to surface treatment by fluoridation or sulfonation.

Polymers such as, for example but not limited to, polyoxymethylenes, vinyl alcohol polymers, polyesters, polyketones, fluorinated polymers, polyacrylonitriles, polyvinylidene halides, liquid crystal polymers, polyamides including aromatic polyamides such as polyarylamides and polyphthalamides, are impermeable to fuel, they constitute a barrier to liquids and / or gases contained in the reservoir so as to minimize the permeability of the reservoir. The thickness of the wall may also be chosen so as to limit the permeability of the reservoir.

Each shell 3 has the shape of a hollow body 4 equipped with an outer peripheral rim. Said shells 3 are positionable against each other by the outer peripheral rim 5 to form the closed enclosure 2 of said reservoir 1.

This enclosure 2 has at least one port 19 for communicating the enclosure with the outside of the enclosure, whose role will be described below. In the example shown, for example in Figure 2, these communication orifices 19 are two in number and are formed by holes through the bottom of the hollow body 4 constituting one of the shells.

Each shell 3 is disposed in a hollow matrix 6, adapted to fit at least a portion of the outer shape of the associated shell 3.

This hollow matrix 6 is preferably made of metal. Each hollow die 6 is in the form of a cup-shaped part, the cavity 7 of which is bordered by an outer peripheral edge 8. The dies 6 are able to fit each at least a part of the outer shape of the associated shell 3, in the arranged state of the shell 3 associated in said die 6 with the rim of the shell 3 at least partially covering the edge 8 external device of the matrix 6, and the bottom of the hollow body of the shell inserting into the cavity 7 of the matrix 6.

Each die 6 may be formed by the impression used to mold the associated shell 3. Each shell 3 can be held inside the associated die 6 by appropriate holding means. Similarly, each shell 3 may have shapes arranged for its holding in position in the associated matrix 6. The dies 6 may be provided with a guide system not shown to ensure their proper alignment.

The tooling formed of the dies comprises, in the positioned state, against each other by their outer peripheral edge of said dies 6, at least one communication orifice 12 of the interior of the volume delimited by said dies 6 with outside.

In the example shown in FIG. 2, the communication orifices 12 are made in the form of orifices passing through the bottom of the cavity 7 of one of the dies. Each communication orifice 12 of the interior of the volume delimited by said matrices 6 with the outside is arranged in correspondence with an orifice 19 for communicating the chamber 2 of the tank 1 with the outside, as illustrated in FIG. 2.

A sealing system, not shown, may be provided to prevent leakage of the pressurized fluid at the orifices.

The outer peripheral edge 8 of at least one of the dies 6 is equipped with a knife 9 adapted to come into bearing contact with the outer peripheral edge 8 or with a knife 9 opposite the other die 6 to the positioned state applies one against the other by their outer periphery edge 8 of said matrices 6. In the example shown in FIG. 2, each die is equipped with a knife 9. In the example shown in FIG. 9, the outer peripheral edge 8 of one of the dies 6 is devoid of knife over at least a part of its length. Alternatively, it could have been planned to equip only one only dies of a knife 9.

This knife 9 is disposed on the die 6 equipped with such a knife 9 at the support zone of the outer peripheral rim 5 of the shell 3 on said die. In the example shown in Figure 2, the knife 9 of each die 6 equipped with a knife 9 extends at least partially within a reservation 1 1 formed in the thickness of the outer peripheral rim 5. the shell 3 associated with said die 6, in the state positioned in abutment with the outer peripheral rim 5 of the shell 3 on said die 6. In the example shown in FIG. 2, the reservation 11 is disposed in the portion of the rim 5 outer peripheral of the shell 3 adjacent the delimiting side wall of the hollow body 4 of the shell 3.

In the example shown in Figure 6, the reservation 1 1 is disposed in the portion of the outer peripheral rim 5 of the shell 3 disposed spaced from the delimiting side wall of the hollow body 4 of the shell.

This knife 9 may be a sharp knife 10 in the form of a sharp edge, as shown in Figure 2.

This knife may still be a knife 9 whose area adjoining the cutting edge 10 is rounded, as shown in FIG. 7A. In this case, the plane 15 of seal obtained at the outer level of the tank 1 is provided with a weld line according to FIG. 7B.

In the example shown in Figure 2, each knife 9 surrounds, in the manner of a continuous wall, the cavity 7 of the associated matrix 6. This wall could have been discontinuous at one of the knives without departing from the scope of the invention.

In the example shown in FIG. 2, each knife 9 is arranged at the level of the inner circumferential portion of the outer peripheral edge 8 adjacent the cavity 7 of the matrix 6. This results in obtaining a tank without a sidewalk or weld line.

In the example shown in FIG. 6, each knife 9 is arranged spaced apart from the inner circumferential portion of the outer peripheral edge 8 adjacent the cavity 7 of the matrix 6. This results in obtaining a reservoir provided on least part of its outer periphery at the joint plane 15, a sidewalk weld.

The knife 9, in this case, here each knife 9 is separated from the outer circumferential portion of the outer peripheral edge 8 of the die 6 by at least one recess 13 of said outer peripheral edge 8 capable of forming a housing for receiving the material in excess of the outer peripheral edges of the shells 3, after crushing the material and cut by the knife or knives 9, as explained below. Finally, to complete the assembly, the cavity 7 of at least one of the matrices 6 is isolated from the outer circumferential portion of the outer peripheral edge 8 of said matrix 6 by at least one flange 14 fixed or movable extending in protruding from said outer peripheral edge 8, this flange 14 being able to form, with the matrix 6 opposite or a fixed or movable rim 14 of the matrix 6 opposite, in the close position of said matrices 6, a barrier of said cavity 7 with 'outside.

An example of a fixed rim 14 is illustrated in FIGS. 10A and 10B, whereas a mobile rim 14, loaded by spring and biased towards the opposite matrix, is represented in FIG. In this embodiment, each die or only one of the dies may be equipped with such a flange. In the embodiment of FIGS. 10A and 10B, where the flange 14 is fixed, this rim 14 comes, in the close position of the dies 6, to be positioned in a hollow recess, formed in the outer peripheral edge 8 of the die 6. look. In order to obtain a reservoir 1 with enclosure 2 closed from shells 3 and the tooling described above, the procedure is as follows: each shell 3 is placed in a hollow matrix with the knife 9 of each matrix 6 equipped with such a knife, adapted to fit into the material of the outer peripheral rim 5 of the associated shell, this rim coming to cover said knife 9.

The knife 9 is housed in the reserve 1 1, provided for this purpose, the portion of the outer peripheral rim 5 of the associated shell 3 bearing on said outer peripheral edge 8 equipped with the knife 9 of the matrix. The orifices 12 and 19 for communicating the dies and the shells are arranged in concordance and are connected to a source of supply of fluid under pressure disposed outside the dies. In the case where there are provided several orifices 12 and 19 of communication, the orifices not connected to a source of pressurized fluid can be closed to allow a subsequent pressurization of the enclosure as described below.

The dies 6 and the shells 3 associated are arranged facing one another and spaced apart from each other as shown in Figure 2.

The manufacturing method then comprises a step of heating the outer peripheral rim 5 and the delimiting lateral wall of the hollow body 4 adjacent to said outer peripheral rim 5 of each shell 3 for softening in the plastic state and / or viscous plastic constituent of each shell 3 at the heated areas.

For the implementation of this heating step, a heating tool 17 is, for example, inserted between the two shells, as shown in FIG. 2. This heating tool 17 can allow heating with or without contact with the parts. to heat, according to its design and according to the material of the shells.

Thus, for example, the heating can be performed using a heating blade, by infrared radiation, by hot gas jet projection or by a combination of these means, or whatever.

When the heating has made it possible to soften the synthetic material constituting each shell 3 in the plastic and / or viscous state, the heating tool 17 is extracted from the space between the two shells 3 and the shells 3 and their shells. associated matrices 6 are brought closer to each other, as illustrated in FIG.

During this approximation, the softened outer periphery edges 5 are crushed and the cutter or knives cut the softened edges of the shells 3. This crushing and cutting generate the formation of at least one bead 16, inside the reservoir chamber 2, at the level of the shell joint plane 15, while another part of the constituent material of the outer peripheral rims 5 comes in the housing formed by the recesses 13 facing the outer peripheral edges 8 of the dies.

In the close position of the shells and associated dies, a fluid under pressure is introduced inside the chamber 2 of the tank 1, through the orifices 12 and 19 for communicating the dies and shells provided for this purpose, these orifices being connectable to a source of pressurized fluid as mentioned above. The orifices 12 and 19 not connected to a source of pressurized fluid and sealed can then be opened for a calibrated exhaust of the fluid contained inside the chamber to accelerate the cooling.

Generally, during the step of introducing a pressurized fluid into the chamber of the tank in order to pressurize said chamber, the fluid is introduced at a pressure of between 0.degree. 1 and 50 bar, preferably between 1 and 8 bar and is selected from the group consisting of air, neutral gases, such as nitrogen.

Maintaining the pressurized chamber operates until the enclosure is cooled to a temperature where the softened portions of the shells allow demolding. This duration of pressurization can be defined empirically for optimization of the cycle time.

The chamber 2 of the tank 1 is then exhausted using, preferably, the same orifices as those used to pressurize the chamber. After exhausting, the shells 3 and the associated dies 6 are spaced from each other, and the reservoir formed by the assembly by welding the shells is extracted from the dies to obtain a reservoir 1 according to FIG. 4.

An additional step of detaching the material 18 from the external peripheral shell rim 3 disposed at the level of the assembly zone of the shells together, outside the chamber 2 of the tank 1, and connected to the enclosure 2 by the cutting area of said outer peripheral flanges 5 resulting from the action of the knife or knives 9 is provided. The tank 1 obtained is then in accordance with FIG. 5. The communication orifices 19 of the tank 1 can then be closed or equipped with, for example, a ventilation device.

Variations in the shape of the outer profile of the joint plane of said enclosure, including the presence of a sidewalk or a weld line, are obtained depending on the shape and arrangement of the knives, as mentioned above. above. Thus, Figure 1A illustrates a tank with no sidewalk or edging while Figure 1B shows a tank locally equipped with a pavement sidewalk.

It should be noted that the tank described above is a monocoque tank. The invention applies equally to multihull tanks, the closed chamber formed by the two shells in the assembled state can then form at least one of the hulls of said tank.

It should be noted that the tightening of anti-pollution standards and the development of hybrid vehicles now force the fuel tanks to withstand a wide range of variation of the internal pressure of the tank (typically of the order of -500 mbar to + 600 mbar). The resistance as well that the dimensional stability of the reservoir under the effect of pressure or depression then take on a significant importance.

For this purpose, the tank may be internally provided with at least one connecting pillar shells between them. Thanks to the presence of this (these) pillar (s), the resistance and the stability of the tank are reinforced.

Each pillar forms before assembly shells together, at each shell, a hollow boss projecting inside the cavity of the shell. The constituent bosses of a pillar extend opposite one another in the state positioned to apply the shells against each other. Each matrix comprises, in turn, a stud which is inserted into a boss of the shell in the disposed state of the shell in the associated matrix.

These studs may or may not be provided with knives as illustrated in FIGS. 13 and 15. At least the vertices of the bosses of the shells are heated during the step of heating the rim of each shell to allow the outcome of the step approaching the shells, welding the bosses between them.

Depending on the shape of the top of the bosses, the bosses may delimit between them a cavity or not.

Claims

1. A process for producing a reservoir (1) with a chamber (2) said closed from at least two shells (3) of synthetic material injection or compression molded, said shells (3) each affecting the shape of a body (4) hollow equipped with an outer peripheral rim (5), said shells (3) being positionable against each other by their outer peripheral rim (5) to form the closed enclosure (2) of said reservoir (1), each shell (3) being arranged in a hollow matrix (6) adapted to fit at least a part of the outer shape of the associated shell (3),

characterized in that the enclosure (2) of the reservoir (1), formed by the two shells (3) in the positioned state, applies one against the other by their outer peripheral rim (5), presenting at least an orifice (19) for communicating the enclosure (2) with the outside of the enclosure (2), and at least one of the matrices (6) being provided at the level of the support zone of the rim (5) external device of the shell (3) on said die (6), a knife (9) adapted to be inserted into the material of the outer peripheral rim (5) of the associated shell (3), said method comprises a step of heating the outer peripheral rim (5) and the delimiting side wall of the hollow body (4) adjacent to said outer peripheral rim (5) of each shell (3) in order to soften the material constituting the each shell (3) at the heated zones, a step of bringing together the shells (3) and dies (6) associated with them until contact of the knife (9) of one of the dies (6) with the other die (6) or a knife (9) carried by the other die (6) with a view to crushing and cutting said outer periphery rims (5), a step of introducing and maintaining a pressurized fluid inside the chamber (2) of the reservoir (1) formed close to the shells (3), a step of exhausting said enclosure (2) of said reservoir (1) and a step of spacing the matrices (6) for demolding the reservoir (1).

2. Method according to the preceding claim,

characterized by comprising an additional step of detaching the material (18) of the external peripheral rim (5) of the shells (3) disposed at the level of the assembly zone of the shells (3) between them, outside the chamber (2) of the reservoir (1). ), and connected to the enclosure (2) by the cutting area of said outer peripheral flanges (5) resulting from the action of the knife or knives (9).

3. Method according to one of the preceding claims,

characterized in that during the step of introducing a fluid under pressure inside the chamber of the tank, for the purpose of pressurizing said chamber, the fluid is introduced at a pressure of between 0.1 and 50 bar and is selected from the group consisting of air, neutral gases, such as nitrogen.

4. Method according to one of the preceding claims,

characterized in that the knife (9) of each die (6) equipped with a knife (9) extends at least partially inside a reservation (1 1) formed in the thickness of the flange (5). ) external device of the shell (3) associated with said matrix (6), in the state positioned in abutment with the outer peripheral edge (5) of the shell (3) on said matrix (6).

5. Method according to one of the preceding claims,

characterized in that at the beginning of the heating step, the outer peripheral rim (5) of said shells (3) has a solidified surface material and softened in the plastic state and / or viscous core.

6. Tooling for implementing a method according to one of claims 1 to 5 for the manufacture of a reservoir (1) enclosure (2) said closed from at least two shells (3). ) for injection or compression-molded synthesis, said shells (3) each having the shape of a hollow body (4) equipped with an outer peripheral flange (5), said shells (3) being positionable by applying thereto; against each other by their external peripheral rim (5) to form the closed enclosure (2) of said reservoir (1), this enclosure (2) closed having at least one orifice (19) for communicating the enclosure with the outside the enclosure (2), said tool comprising two hollow matrices (6), each matrix (6) being in the form of a cup-shaped part whose cavity (7) is bordered by an outer peripheral edge (8), said matrices (6) being able to fit each at least a part of the outer shape of the shell (3) associated, in the arranged state of the shell (3) associated in said matrix (6) with the rim of the shell (3) overlapping at least partially outer peripheral edge (8) of the matrix (6), characterized in that the outer peripheral edge (8) of at least one of the dies (6) is equipped with a knife (9) adapted to come into operation. bearing contact with the outer periphery edge (8) or with a knife (9) facing the other die (6) in the positioned state against each other by their peripheral edge (8) external of said matrices (6) and in that said tooling comprises, in the positioned state, one against the other by their peripheral edge (8) and xterne said matrices (6), at least one orifice (12) of communication of the interior of the volume defined by said matrices (6) with the outside.

7. Tooling according to claim 6,

characterized in that the knife (9) of at least one of the dies (6) surrounds in the manner of a continuous or discontinuous wall the cavity (7) of the matrix (6).

8. Tooling according to one of claims 6 or 7,

characterized in that the knife (9) of at least one of the dies (6) is arranged, at least locally, spaced apart from the inner circumferential portion of the outer peripheral edge (8) adjoining the cavity (7) of the matrix (6).

9. Tooling according to one of claims 6 to 8,

characterized in that the knife of at least one of the dies (6) is separated from the outer circumferential portion of the outer peripheral edge (8) of the die (6) by at least one recess (13) of said edge (8). ) external device capable of forming a receiving housing of the material in excess of the outer peripheral edges (5) of the shells (3) after cutting by the knife or knives (9).

10. Tooling according to one of claims 6 to 9, characterized in that the cavity (7) of at least one of the dies (6) is isolated from the outer circumferential portion of the outer peripheral edge (8) of said die (6) by at least one fixed flange (14) or movable protruding from said outer peripheral edge (8), this flange (14) being adapted to form, with the matrix (6) facing or a flange (14) fixed or movable matrix (6) facing in a position close to said matrices (6), a barrier of said cavity (7) with the outside.

1 1. Container (1) with enclosure (2) said closed comprising at least two shells (3) of synthetic material injection-molded or compression and weldable at their plane (15) joint,

characterized in that, in the welded state of the two shells (3), the reservoir (1) has, in the region of the joint plane (15), a corrugated profile with the longitudinal axis of each wave developing substantially parallel to the plane (15) of the seal in the manner of a bead (16) developing on the inner periphery of the enclosure (2).

12. Reservoir (1) according to claim 1 1,

characterized in that the reservoir (1) is at least partially free, outside the reservoir, at the plane (15) of joint, sidewalk or weld.

13. Tank (1) according to one of claims 1 1 or 12,

characterized in that said shells (3) each have, prior to joining by welding, the shape of a hollow body (4) equipped with an outer peripheral rim (5), said shells (3) being positionable to apply one of them against the other by their external peripheral rim (5) to form the enclosure (2) closed said tank (1), the tank (1) having, in the position of shells (3) applied against one against the other by their outer peripheral rim (5), at least one orifice (19) for communicating the enclosure (2) with the outside.

Tank (1) according to claim 13,

characterized in that each shell (3) has, on at least a portion of the length of the outer peripheral rim (5), a thickness of the outer peripheral rim (5) greater than the thickness of the delimiting lateral wall of the hollow body (4) adjoining said rim (5).