EP2539143A1

EP2539143A1 - Method for producing a large-capacity, pliable container and inner protective envelope produced during said method

Info

Publication number: EP2539143A1
Application number: EP11712638A
Authority: EP
Inventors: Jacques Basconnet
Original assignee: Tisza Textil Packaging SAS
Current assignee: Tisza Textil Packaging SAS
Priority date: 2010-02-26
Filing date: 2011-02-24
Publication date: 2013-01-02
Anticipated expiration: 2031-02-24
Also published as: BR112012021107B1; BR112012021107A2; ES2558311T3; FR2956834A1; PL2539143T3; FR2956834B1; US20120312865A1; EP2539143B1; US9199424B2; WO2011104485A1; HUE025813T2; CA2791127C; SI2539143T1; DK2539143T3; CA2791127A1

Abstract

The invention relates to a method for producing a large-capacity, pliable container, comprising a step of a) producing a tubular bellow-type sleeve, a step b) of cutting the tubular bellow-type sleeve, a step c) of cutting lateral folding regions of the folded bellow-type sleeve, a step d) of soldering adjacent cutting edges in such a way as to produce a parallelepipedic inner protective envelope having a square cross-section (1b), and a step e) of sticking fixing lugs (13) to two lateral fixing faces (14a, 14b) located opposite the folded bellow-type sleeve. According to the invention, the method comprises a step f) of applying a tractive force to the fixing lugs (13) in order to deform, by stretching, the parallelepipedic inner protective envelope having a square cross-section, and to obtain a parallelepipedic inner protective envelope having a rectangular cross-section (1), a step g) of soldering the outer lateral pockets (17a, 17b), a step h) of cutting the outer lateral pockets (17a, 17b), and a step B) of assembling the inner protective envelope having a rectangular cross-section (1) with the outer envelope in order to form said large-capacity, pliable container.

Description

Process for manufacturing a flexible container of large capacity and internal protective envelope obtained during this process

The invention relates to a method of manufacturing a flexible container of large capacity, and an internal protective envelope obtained during this process.

Large capacity flexible containers are used in the pharmaceutical or chemical industry, for example.

They are intended to contain semi-finished products and finished products in solid form such as powders, granules, tablets, or capsules, for example.

They are made of plastic and have capacities ranging from 100 L to

600 L.

They include an internal protective envelope intended to be inserted into an outer envelope.

The packaging, consisting of two inner and outer envelopes, is disposable after use, which ensures its perfect cleanliness since it is used only once. This feature avoids the risk of contamination, unlike rigid reusable containers that should be washed, sanitized, identified. The unit cost of use is much lower in the end and eliminates the risk of mixing between two lots.

The known outer shells are made of a woven polymeric material such as polypropylene, for example, which is a strong material, allowing the outer sheath to withstand a load of from a few tens of kilograms to over 500 kg.

The different elements of the outer envelope are obtained by cutting and are assembled by sewing.

The internal protective envelope, commonly known as "liner", must be one hundred percent waterproof. Its function is to protect the contents of the flexible container from its environment (humidity, odor, light, gas).

The internal protective envelope is made of a polymer material, such as polyethylene, for example. It can also be made from more noble materials such as laminated complexes based on aluminum, polyamide or technical plastics giving it more specific properties. The materials used and the methods of manufacturing the internal protection casings must meet the standards of the pharmaceutical industry, and in particular the constraints concerning cleanliness, the absence of pollution and the absence of germs.

The inner protective casing is assembled with the outer casing to form the flexible container of large capacity.

The large capacity flexible containers 2 of the prior art, as illustrated in FIG. 1, have a parallelepipedal shape with a square section.

The flexible containers 2 are intended to be inserted in a metal frame 2a and supported by it.

The square-section parallelepiped shape of the flexible containers limits their use to square-section metal frames.

Out of this, the majority of storage racks used in the pharmaceutical industry, for example, are configured to accommodate containers of rectangular section.

The insertion of a flexible container of square section in a metal frame of rectangular section causes a loss of storage volume.

There is therefore a need for flexible containers having a rectangular section to increase the storage capacities and to be able to use them in metal frames with rectangular section which are widely used in the industry.

Nevertheless, such flexible containers with a rectangular section are difficult to manufacture.

Indeed, the manufacturing methods of the prior art do not make it possible to obtain an internal protective envelope with a rectangular section.

Such internal protection envelopes of rectangular section can not be obtained with the only folding operations, cutting and welding usually used in this sector.

In particular, these operations do not make it possible to obtain internal protection envelopes of rectangular section having chutes of square section.

The usual folding methods limit the shape of the sections to square shapes.

Thus, the object of the invention is to propose a method of manufacturing a flexible container of large capacity of rectangular section that also makes it possible to avoid pollution of the inside of the internal protective envelope during its manufacture. To this end, the invention relates to a method of manufacturing a flexible container of large capacity comprising an inner plastic protective envelope intended to be inserted into an outer envelope, said method comprising the following successive steps:

A) manufacture of the internal protection envelope by:

a) obtaining a bellows tubular sheath by an extrusion blow molding process comprising a pleat forming operation on the bellows tubular sheath, said bellows tubular sheath being in folded form after step a),

b) cutting a portion of the bellows tubular sheath to provide a folded bellows sheath having a rectangular shape, said folded bellows sheath having two opposed open ends, and two folded lateral zones separated by a central longitudinal axis, each lateral folding zone comprising three fold lines, including an inner fold line extending along and near the central longitudinal axis, and two outer fold lines,

c) cutting the lateral fold zones, at the four corners of the folded bellows duct so as to obtain a folded bellows duct having two narrowed portions at its open ends, each of said narrowed portions being delimited by two cut lateral edges comprising each a stack of four cutting edges,

d) welding cutting edges adjacent to each other, for each of said cut side edges, so as to obtain, when the folded bellows sheath is unfolded, a parallelepipedal internal protection envelope of square section comprising a square section chute to its upper and lower extremities, and

e) bonding fastening tabs on two opposite lateral fixing faces of the folded bellows sheath, each of these lateral fastening faces comprising at least four fastening tabs.

According to the invention, the method comprises the following steps:

f) application of a tensile force on the fastening tabs to deform by stretching the parallelepiped internal protection envelope of square section and to obtain a parallelepipedal internal protection envelope of rectangular section, said inner protective envelope of rectangular section comprising four lateral faces whose two lateral faces of attachment, and two opposite rectangularly shaped lateral faces each having an upper edge, a lower edge, and two outer side pockets respectively extending along said upper and lower edges,

g) welding the outer side pockets to isolate them from the rest of the rectangular section internal protection envelope,

h) cutting the outer side pockets to remove them from the two stretched lateral faces,

B) assembling the rectangular section inner protection envelope with the outer envelope to form said flexible container of large capacity.

In various possible embodiments, the present invention also relates to the following features which may be considered individually or in all their technically possible combinations and each bring specific advantages:

during step e) of gluing the fastening lugs, four fastening lugs are glued to each of the lateral attachment faces of the folded bellows sheath, said fastening lugs being adjacent to the four corners of the lateral fastening faces,

the fixing lugs are adhesive fastening lugs having the shape of a T,

step c) of cutting the lateral zones of folding comprises, for each lateral folding zone, two cutting operations to obtain two cuts symmetrical with respect to the central longitudinal axis, each cutting operation being carried out according to a first cutting line oblique with respect to the central longitudinal axis and along a second cutting line parallel to the central longitudinal axis,

the cutting steps b), c) and h) are carried out by ultrasound or by means of a hot blade,

the welding steps d) and g) are carried out by thermo-welding, the step g) of welding the external side pockets is carried out outside the internal protective envelope,

the outer casing comprising a plurality of panels of polymeric material, including an upper panel, two small side panels, and two large area side panels, during the assembly step B), the outer casing is formed by sewing said panels around the internal protective envelope of rectangular section, so as to integrate it into the outer casing, the fastening lugs of the inner protective envelope of rectangular section being embedded in the seams formed between said panels,

the fastening tabs are positioned on the lateral edges of the rectangular section of internal protection envelope, said fastening tabs passing through the outer envelope at the lateral edges of the latter.

The invention also relates to an internal protection envelope obtained during the method of manufacturing an internal protective envelope as defined above. The inner protective envelope has a parallelepipedal shape of rectangular section and comprises a chute of substantially square section on its upper and lower faces.

Thus, the invention provides a method for manufacturing a rectangular parallelepiped shaped large capacity flexible container without polluting the interior of the internal protective envelope.

The rectangular shape of the internal protective envelope is obtained without intervention within it.

The Rectangular Inner Protection Envelopes meet an industry need in which the majority of metal frames, and used storage racks have a rectangular section.

The invention will be described in more detail with reference to the accompanying drawings in which:

- Figure 1 shows a flexible container of square section of the prior art mounted in a metal frame;

Figure 2 shows a folded bellows sheath according to one embodiment of the invention;

FIG. 3 represents a folded bellows sheath with two parts narrowed at its ends, obtained after a cutting step c) and a step d) of cutting edge welding, according to one embodiment of the invention;

FIG. 4 represents a folded bellows duct, obtained after a step e) of bonding of the support tab on two lateral faces of opposing fastening of the folded bellows sleeve according to one embodiment of the invention;

FIG. 5 represents an internal protection envelope of square section;

FIG. 6 shows a square section internal protection envelope, during a step f) of applying a traction force on the fastening tabs to obtain an internal protection envelope of rectangular section, according to an embodiment of FIG. the invention;

FIG. 7 represents this rectangular section internal protection envelope, obtained after the steps g) of welding and h) of cutting the external lateral pockets, according to one embodiment of the invention;

FIG. 8 shows part of step B) of assembling the rectangular section internal protection envelope with the outer envelope to form a flexible container of large capacity;

Figure 9 shows a flexible container of large capacity rectangular section obtained by the method of the invention;

Figure 10 shows this flexible container of rectangular section mounted in a metal frame.

The method of manufacturing a flexible container of high capacity 2 comprises a step a) of obtaining a tubular jacket with bellows by an extrusion / blowing process comprising a fold forming operation. The gusseted tubular sheath is in the form of a folded sheath folded after step a).

The method of manufacturing a high capacity flexible container 2 comprises a step b) of cutting a portion of the bellows tubular sheath to obtain a folded bellows sheath 1a, as shown in FIG.

This bent folded sheath 1a is made of polymer material, preferably polyethylene.

It can also be made from more noble materials such as laminated complexes based on aluminum, polyamide or technical plastics giving it more specific properties.

Folded bellow duct 1a has a rectangular shape. It comprises two opposite open ends 4a, 4b, and two lateral folding zones 5a, 5b separated by a central longitudinal axis 6. Each lateral folding zone 5a, 5b comprises three fold lines 7a, 7b, 7c including an inner fold line 7b extending along and near the central longitudinal axis 6, and two outer fold lines 7a, 7c .

In other words, each lateral fold zone 5a, 5b forms a bellows having three folds, one of which is a central fold.

The inner folding lines 7b of the two lateral folding zones 5a, 5b are contiguous. The two lateral folding zones 5a, 5b are symmetrical with respect to the central longitudinal axis 6.

The method of manufacturing a flexible container of high capacity 2 comprises a step c) of cutting the lateral folding zones 5a, 5b, at the angles 8 of the folded bellows sheath 1a to obtain a bellows duct folded 1a having two narrowed portions 9a, 9b at its open ends 4a, 4b, as shown in FIG.

Each of the narrowed portions 9a, 9b is delimited by two cut lateral edges 10a, 10b each comprising a stack of four cutting edges 11.

The number of cutting edges 1 1 is related to the number of folds or fold lines. Indeed, three fold lines correspond to four layers stacked on each other to form a bellows. Cutting the four stacked layers causes the formation of four cutting edges 1 January.

Each lateral folding zone 5a, 5b or each bellows having two outer fold lines 7a, 7c, there are two cuts to be made for each angle 8 of the bellows duct. In fact, there are altogether eight portions located in the corners of the bellows tubular duct portion that are cut to obtain constrictions at the ends.

The step c) of cutting the lateral zones of folding comprises, for each lateral folding zone 5a, 5b, two cutting operations making it possible to obtain two cuts symmetrical with respect to the central longitudinal axis 6. Each cutting operation is carried along a first oblique cutting line 18 with respect to the central longitudinal axis 6 and along a second cutting line 19 parallel to the central longitudinal axis 6.

Falls 36 or unused cut parts are removed.

The narrowed portions 9a, 9b have a flared rectangle shape. The method of manufacturing a flexible container of large capacity 2 comprises a step d) of welding the cutting edges 1 1 adjacent to each other, for each of the cut side edges.

The cutting and welding steps are preferably performed simultaneously.

When the folded bellows duct 1a is unfolded, a parallelepipedal internal protective envelope of square section 1b comprising a chute 12a, 12b of square section at its upper ends 23a and lower 23b, as shown in FIG. 5, is obtained.

The internal protective envelope comprises a filler neck 1a at the upper end 23a of the inner protective envelope, and a discharge chute 12b at the lower end 23b of the inner protective envelope.

The internal protective envelope of square section 1b extends in the lower and upper part by a frustoconical portion 32 of pyramidal section having four faces 33. Each frustoconical portion 32 is terminated by one of the troughs 12a, 12b whose reduced section allows adapt the product flow to the constraints of the receiving equipment. Each frustoconical portion 32 connects one of the chutes 12a, 12b to the rest of the internal protective envelope.

The two chutes 12a, 12b may have identical dimensions, in particular the same height and faces of the same width.

Preferably, they have heights and faces of different widths, as shown in FIG.

Alternatively, the chutes 12a, 12b may have a rectangular section.

In FIG. 5, the chute 12a positioned at the upper end 23a of the square section internal protection envelope 1b has a greater height than the chute 12b positioned at the lower end 23b of the internal protection envelope. square section 1 b. It also has a wider section, that is to say, faces of greater width.

The welding is done by thermo-welding.

Each lateral folding zone 5a, 5b or each bellows having two outer fold lines 7a, 7c cut, there are two welds to be made for each cut side edge 10a, 10b of the bellows sleeve.

The cutting edges 1 1 cut edge edges 10a, 10b are all welded to each other so as to reform a bellows. Each lateral folding zone 5a, 5b again comprises three fold lines 7a, 7b, 7c, including an inner fold line 7b extending along and near the central longitudinal axis 6, and two outer fold lines 7a. , 7c.

The outer fold lines 7a, 7c are each formed of a central portion 24a parallel to the central longitudinal axis 6, of two oblique portions 24b forming an angle with the central longitudinal axis 6, disposed on each side of the central portion 24a, and two lateral portions 24c parallel to the central longitudinal axis 6.

The method of manufacturing a flexible container of large capacity 2 comprises a step e) of bonding fastening lugs 13 on two opposite lateral attachment faces 14a, 14b of the folded bellows sheath 1a. Each of these lateral fixing faces 14a, 14b comprises at least four fixing lugs 13.

Step e) of bonding the fastening lugs 13 is performed when the tubular gusseted sheath is folded.

Preferably, four fastening lugs 13 are glued to each of the lateral fixing faces 14a, 14b of the folded bellows sheath 1a, as illustrated in FIGS. 4 and 5.

The fastening tabs 13 are adjacent to the four corners 25 of the lateral fixing faces 14a, 14b.

The fastening lugs 13 are adhesive fastening lugs having the shape of a T, and made of a reinforced flexible material.

Alternatively, the fastening lugs 13 may be glued to the lateral edges 21 of the square section internal protection envelope 1a. Their number may be greater than four.

The method of manufacturing a flexible container of large capacity 2 comprises a step f) of applying a tensile force on the fastening tabs 13 to deform by stretching the parallelepipedal internal protective envelope of square section 1 b, and obtain a parallelepipedal internal protective envelope of rectangular section 1, as shown in FIG. 6.

The rectangular section inner protection envelope 1 comprises four lateral faces whose two lateral fixing faces 14a, 14b, and two opposite rectangularly elongated lateral faces 15a, 15b, each having an upper edge 16a, a lower edge 16b, and two outer side pockets 17a, 17b respectively extending along the upper edges 16a and lower 16a. The two outer side pockets 17a, 17b are generated by stretching the stretched lateral faces 15a, 15b opposite.

The adhesion of the fastening lugs 13 to the internal protective envelope must be sufficient so that the fastening lugs 13 do not detach during step f).

The stretching is performed until the desired shape for the internal protective envelope is obtained.

Advantageously, the traction forces are applied simultaneously on all the fastening lugs 13.

The upper faces 23a and 23b of the inner protective envelope are also stretched and have a rectangular shape.

After deformation, the chutes 12a, 12b substantially keep a square section.

The stretching is done manually or mechanically from outside the internal protective envelope, without risk of pollution inside the internal protective envelope.

The method of manufacturing a flexible container of large capacity 2 comprises a step g) of welding the outer side pockets 17a, 17b to isolate them from the rest of the internal protective envelope of rectangular section 1, and a step h) of cutting the outer side pockets 17a, 17b to remove them from the two stretched side faces 15a, 15b.

Steps g) and h) are performed outside the internal protective envelope, avoiding any risk of pollution inside the internal protective envelope.

An internal protective envelope of rectangular section 1 is obtained without external lateral pockets 17a, 17b, as illustrated in FIG. 7.

The welding steps d) and g) are carried out by thermo-welding.

The cutting steps b), c) and h) are performed ultrasonically to prevent smoke generation and the use of extractor hoods. Alternatively, the cutting steps b), c) and h) can be performed by a hot blade technique (350 ° C).

The method of manufacturing a flexible container of large capacity 2 comprises a step B) of assembling the rectangular section 1 internal protection envelope with the outer envelope 3 to form the flexible container of large capacity 2, as shown in Figure 8.

The outer casing 3 is manufactured by assembling five panels including an upper panel 26, two small side panels 27, and two panels. These panels are made of polymer materials, such as polypropylene, for example.

Each small surface side panel 27 includes a square or rectangular top portion 27a. Each large-area side panel 28 includes a rectangular upper portion 28a.

Each side panel 27, 28 comprises an intermediate portion 27b, 28b intended to form a lower frustoconical portion 30 for the outer envelope 3.

Each side panel 27, 28 comprises a lower part 27c, 28c intended to form a discharge chute 31 for the outer envelope 3.

During the assembly step B), the outer envelope 3 is formed by sewing the panels 26, 27, 28 which are positioned around the internal protective envelope of rectangular section 1, so as to integrate it in the outer shell 3.

In other words, the outer envelope 3 is sewn around the inner protective envelope of rectangular section 1.

The fastening lugs 13 are integrated into the seams making it possible to assemble the panels 26, 27, 28 of the outer envelope 3, and pass through the outer envelope 3 through locations 20.

The internal protective envelope of rectangular section 1 is thus secured to the outer shell 3 by means of the fixing lugs 13.

The inner protective envelope of rectangular section 1 is deployed in the outer casing 3 so that it matches its shape. The eight fastening lugs 13 of the rectangular section internal protection envelope 1 are associated with eight locations 20, as shown in FIG. 9.

In a preferred manner, the fastening lugs 13 of the rectangular section internal protection envelope 1 are positioned on the lateral edges 21 of the rectangular section internal protection envelope 1. The locations 20 of the outer casing 3 are positioned on the lateral edges 22 of the outer casing 3 to face the fixing lugs 13, and to ensure that the entire volume of the internal protective casing 1 is deployed. in the outer shell 3.

These fixing means do not call into question the tightness of the inner protective envelope 1 and ensure a perfect coherence of the shapes of the two envelopes 1, 3. This is very important when it comes to packaging drugs because the emptying of the internal protection casing 1 must be total without that it is necessary to intervene inside to facilitate the fall of the last contained parts.

The side panels 27, 28 are sewn together first to form an outer shell body. The upper panel 26 is then sewn on the upper part of the body of the outer casing.

The upper panel 26 comprises a flat portion 37 surmounted by a filler neck 38 of cylindrical shape, with a circular or oblong section. It can also be of parallelepipedal shape.

The filler neck 12a of the inner protective casing 1 is intended to partially emerge through this filler neck 38 of the outer casing 3.

The upper panel 26 comprises fixing slots 34 distributed around its periphery.

The flexible container of large capacity 2 is intended to be inserted in a metal frame 2a which serves as a supporting structure, as shown in FIG. 10, and which gives the assembly a format that can be easily integrated into standard storage racks, and that can be adapted the various filling and emptying equipment of the pharmaceutical industry.

The fixing slots 34 of the upper panel 26 of the outer shell 3 are inserted into pins 35 projecting from the upper edge of the metal frame 2a.

The manufacturing method of the invention thus makes it possible to manufacture flexible containers of large capacity 2 of rectangular parallelepiped shape without polluting the inside of the internal protective envelope 1.

The flexible containers of large capacity 2 may have a rectangular section of 68 x 108 mm, for example, and be housed in metal frames of 79 x 19 mm.

Claims

1. A method of manufacturing a flexible container of large capacity (2), said container comprising an inner protective envelope (1) of plastic material intended to be inserted into an outer envelope (3), said method comprising the following successive steps:

A) manufacture of the internal protection envelope (1) by:

b) cutting a portion of the bellows tubular sheath to provide a folded bellows sheath (1 a) having a rectangular shape, said folded bellows sheath (1 a) comprising two opposed open ends (4a, 4b), and two lateral folding zones (5a, 5b), separated by a central longitudinal axis (6), each lateral folding zone (5a, 5b) comprising three fold lines (7a, 7b, 7c) including an inner fold line ( 7b) extending along and near the central longitudinal axis (6), and two outer fold lines (7a, 7c),

c) cutting the folding side regions (5a, 5b) at the four corners (8) of the folded bellows duct (1 a) so as to obtain a folded bellows duct (1 a) having two narrowed portions ( 9a, 9b) at its open ends (4a, 4b), each of said narrowed portions being delimited by two cut side edges (10a, 10b) each comprising a stack of four cutting edges (1 1),

d) welding the cutting edges (1 1) adjacent to each other, for each of said cut side edges (10a, 10b), so as to obtain, when the folded bellows sleeve (1 a) is unfolded, an envelope of parallelepiped internal protection of square section (1b) comprising a trough (12a, 12b) of square section at its upper (23a) and lower (23b) ends, and

e) bonding fastening lugs (13) on two opposite lateral fixing faces (14a, 14b) of the folded bellows sheath (1 a), each of these fixing lateral faces (14a, 14b) comprising at least four legs fastening (13), characterized in that it comprises the following steps:

f) application of a tensile force on the fixing lugs (13) to deform by stretching the parallelepiped internal protective envelope of square section (1 b), and to obtain a parallelepipedal internal protective envelope of rectangular section (1) , said rectangular section internal protection envelope (1) comprising four lateral faces, the two lateral fixing faces (14a, 14b), and two opposite rectangularly shaped lateral faces (15a, 15b) each having an upper edge (16a). ), a lower edge (16b), and two outer side pockets (17a, 17b) respectively extending along said upper (16a) and lower edges

(16a)

g) welding the outer side pockets (17a, 17b) to isolate them from the remainder of the rectangular section inner protective envelope,

h) cutting the outer side pockets (17a, 17b) to remove them from the two stretched side faces (15a, 15b), and

B) assembling the rectangular section inner protection casing (1) with the outer casing (3) to form said large capacity flexible container (2).

2. A method of manufacturing an internal protective envelope as part of a process for manufacturing a flexible container of large capacity (2) according to claim 1, characterized in that, during step e) of bonding the fastening lugs (13), four fastening lugs (13) are adhered to each of the lateral fastening faces (14a, 14b) of the folded bellows sleeve (1a), said fastening lugs (13) being adjacent at the four corners (25) of the fixing side faces (14a, 14b).

3. A method of manufacturing an inner protective envelope according to claim 2, characterized in that the fastening lugs (13) are adhesive fastening tabs having the shape of a T.

4. A method of manufacturing an internal protective envelope according to any one of claims 2 to 3, characterized in that the step c) of cutting the lateral folding zones comprises, for each lateral folding zone (5a, 5b), two cutting operations to obtain two cuts symmetrical with respect to the central longitudinal axis (6), each cutting operation being performed along a first oblique cutting line (18) with respect to the central longitudinal axis (6) and according to a second cutting line (19) parallel to the central longitudinal axis (6).

5. A method of manufacturing an internal protective envelope according to any one of claims 2 to 4, characterized in that the cutting steps b), c) and h) are performed by ultrasound or by means of a blade hot.

6. A method of manufacturing an internal protective envelope according to any one of claims 2 to 5, characterized in that the welding steps d) and g) are carried out by thermo-welding.

7. A method of manufacturing an internal protective envelope according to any one of claims 2 to 6, characterized in that the step g) of welding the outer side pockets (17a, 17b) is performed outside of the internal protection envelope (1).

8. A method of manufacturing an internal protective envelope according to any one of claims 2 to 7, characterized in that, the outer casing (3) comprising a plurality of panels of polymeric material including an upper panel (26), two side panels of small area (27), and two side panels of large area (28), during the assembly step B), the outer envelope (3) is formed by sewing said panels around the envelope of internal protection of rectangular section (1), so as to integrate it into the outer casing (3), the fastening tabs (13) of the rectangular section internal protection casing (1) being integrated in the seams formed between said panels.

9. A method of manufacturing an internal protective casing according to claim 8, characterized in that the fastening tabs (13) are positioned on the lateral edges (21) of the rectangular section internal protection casing (1). , said fixing lugs (13) passing through the outer casing (3) at the lateral edges (22) thereof.

10. Inner protection casing (1) characterized in that it is obtained during the manufacturing process of an internal protective casing (1) as defined by claims 2 to 9, said internal protective casing (1). ) having a parallelepipedal shape of rectangular section and comprising a chute (12a, 12b) of substantially square section on its upper (23a) and lower (23b) faces.