Patent Application
20240239558
The invention concerns a flexible bag with bellows and a bottom that is transformable, in particular to obtain a square bottom. The invention also concerns a continuous process and a machine for making such flexible bags using a sheet of flexible material, in particular paper.
Industrial processes for manufacturing bags made of flexible materials such as paper or synthetic material have been known for a long time. For example, document FR 1 270 400 describes a process for manufacturing such bags. A continuous sheet of paper is unreeled then cuts are made on the edges in such a way as to free up bonding seams that are symmetrical with respect to a longitudinal middle of the sheet extending along an area of the sheet we call the first flap. The seams are folded longitudinally on the sheet and coated with adhesive on the upper face, opposite the first flap. The sheet is cut into sections, for example by a clean cut and folded along a transversal crease to delimit a second flap which is folded over the first flap. The second flap is thus bonded to the seams and the container is delimited between the first flap and the second flap. When you want the bag to form an envelope, the cut is made in such a way that a tab remains prolonging the first flap opposite the transversal crease. It is thus possible to manufacture bags at a high rate with a large variety of materials and formats.
Document WO 2016 097310 A1 shows an example of bags comprising bellows. This document also shows a machine that is used to form an envelope from the tube using two stations each of which comprises a pair of contra-rotary cylinders whose work makes it possible to make a separation into sections and tear off a waste piece to reveal a tab at the front of the section on the same wall as the rear tab. Thus, after being folded, the tabs are applied to the same wall.
When manufacturing the bags, the removal of the waste piece is a limitation: on the one hand, it can be seen this is a limiting factor for the speed of bag manufacturing, and on the other hand the large amount of waste pieces is always a constraint that must be managed. Furthermore, the adjustment of such a machine requires a high level of technical expertise. A great deal of time is required to make the adjustment when changing the format of the bags, particularly in the case of a change of width, because the means of perforation will have to be changed and adjusted.
The fact of making a clean cut instead of tearing gives a bag with a quality that is perceived as being better, the edge being sharper. However, this process also generates waste when making the lateral seams.
Document EP-3564146-A1 shows a bag manufacturing process that is quite similar to that in FR 1 270 400, but differs in that no cut is made in the edge. The flaps folded one on the other are bonded together along the edges. The process therefore does not generate any waste, but the useful width of the bag is reduced by the width of the areas bonded to each other. Furthermore, this type of bonding is more fragile because the constraints for separating one flap from the other are concentrated on the edge of the adhesive area.
We also know of bags with a square bottom where the advantage is that they can more easily be stood on their bottom and stay open. Documents U.S. Pat. No. 687,679A, FR 1 120 408, WO2020/049376 A1, FR 2 054 249 A5 and EP 2 864 114 B1 describe examples of bags and of machines for making such bags.
The manufacturing operations for such a bag are much more complex than those for a flat bag in such a way that the production rates are much more limited.
In order to produce bags which have the possibility of being used as square-bottomed bags, document WO 2020/120616 A1 shows a technique for transforming a flat bag into a square-bottomed bag. This method, enabling production at a high rate, is not suited to all types of bag however, in particular when the material is a low-grammage paper.
One of the objectives of the invention is to produce bags with bellows that can be used as square-bottomed bags and that can be produced at a high rate.
With these objectives in mind, the object of the invention is a bag made of a flexible material comprising a first and a second flap comprising cheeks along their edges, the cheeks being linked to form two bellows linking the flaps, one end of the bag perpendicular to the edges being closed, the bag being characterised by the fact it comprises a system with at least one reinforcement panel extending over a central part of the flaps, between the bellows.
By adding at least one reinforcement panel to the bag with bellows, it is possible to provide walls with different degrees of stiffness, which makes it possible to give it a better resistance when the bag is deployed, before and after filling. As the panel is delimited outside the bellows, the separation of the flaps tends to keep a parallelism between the flaps while obtaining the deployments of the bellows, owing to the stiffness reinforced by the panel system on the flaps. Different configurations are possible, as shown by the rest of the discussion. For example, the flexible material could be paper with grammages varying, for example, between 40 and 150 g/m2, synthetic material, textile or a combination of these materials. The reinforcement panels have, for example, a grammage greater than 100 g/m2, for example greater than 250 g/m2, or even greater than 300 g/m2. The panels also make it possible to provide additional functionalities, such as a protection against impacts or a thermal insulation. The visual appearance of the exterior of the bag remains more or less the same as that without panels, the reinforcement panels being hidden inside the bag. Each reinforcement panel can be formed by superposing multiple layers. The materials can be varied such as embossed paper to provide a layer of mechanical and thermal protection, a sheet of synthetic foam or including bubbles, or a reflective sheet.
As per an improvement, each flap comprises a crease marking line, one opposite the other to delimit a bottom at the closed end. The marking line facilitates folding of the flap at this level, which makes it possible to delimit a rectangular-shaped bottom linking the rest of the flaps together to each other.
As per a first accomplishment mode, the system with at least one panel comprises a first and a second panel extending respectively over the first and second flap, the panels being separated at the level of the closed end. The reinforcement provided by the panel system is interrupted at the level of the closed end, which makes it possible to store the bag while being folded at this level. This crease does not provide much resistance when opening the bag since it is not reinforced by the panels.
As per an improvement to the first accomplishment mode, the first and second panels extend only beyond the marking lines with respect to the bottom. Thus, only the walls beyond the bottom are reinforced, which allows the bottom to conform to the position conferred by the walls.
As per a second accomplishment mode, the system with at least one panel comprises a third panel extending over the first and second flaps. This panel, which replaces the first and second panels of the previous accomplishment mode, makes it possible to stiffen the bottom, in such a way that the walls follow its shape when the bag is deployed and when it is filled.
As per an improvement to the first or second accomplishment mode, the system with at least one panel only extends short of the marking lines on the bottom side. The system with at least one panel allows the walls to fold easily at the level of the marking lines, while conferring a shape with one or two pieces on the bottom.
As per an alternative improvement, the panel system extends on both sides of the marking lines, the marking lines also being formed on the system with at least one panel. The system with at least one panel therefore also extends along the beginning of the walls, which makes it possible to stiffen both the bottom and the beginning of the walls, or even the whole height of the walls.
As per an improvement, each bellows cheek is stuck against the adjacent flap according to a corner area extending to the corner of the central part of the flap between the closed end and the marking line on said flap. In this corner area and when deploying the bag, the bellows cheek remains naturally in contact with the central part of the flap. By bonding these parts in this area, the deployment is facilitated in the shape of the bottom by giving it a greater stiffness, owing to the bonding of two thicknesses together.
As per a constructive disposition, the corner area takes the form of a right triangle whose right-angle corner is in a corner of the central part of the flap. The formation of a crease is facilitated along the hypotenuse of the triangle, which corresponds to the configuration of a “square” bottom in the presence of bellows.
As per an improvement, a second strip of flexible material is bonded inside the bag and covers at least the system with at least one reinforcement panel. This layer makes it possible to confer specific surface properties on the interior of the bag and, in particular, to enclose the system with at least one panel. For example, this additional layer provides the interior of the bag with a smooth surface in the case where an embossed reinforcement is used, or with a rough or adhesive surface, or with a watertight surface.
The object of the invention is also a process for manufacturing a bag with a flexible material, whereby:
This process makes it possible to produce bags as described previously without producing waste, so without limitation on the production rate caused by having to manage the removal of such waste. The process uses the principle described in document FR 1 270 400 but without having to cut the edges. Indeed, the edges are folded over their whole length to form the cheeks of the bellows and hems and the latter are folded one onto the other after application of adhesive to assemble the two folded flaps one on the other. Cutting can be achieved by a clean-cutting means, that is to say by shearing, which gives a good perceived cutting quality. Cutting could also be achieved with a toothed knife cooperating with a groove to obtain the separation without any prior perforation lines. Cutting could also be obtained by tearing, that is to say by traction on a portion that has perforations initiating a cutting line. The cutting system is the same whatever the width of the bag to be made. It is therefore easy to change the width.
As per an improvement, a second strip of flexible material is unreeled using a second unwinding means, a second application of adhesive is made using a second adhesive application means, and the second strip and the first strip are brought together on the internal face of the first strip so the second strip at least covers the system with at least one reinforcement panel and is bonded to it. The two layers are assembled before folding, which makes it possible to have this second layer inside the bag. Preferably, it extends over the same length as the first layer.
As per a constructive disposition, the widths of the first and second strips are different in such a way that the hems extend from just one of said strips. This makes it possible to have a layer that serves as mechanical reinforcement for the other layer without, however, hindering folding the hems when forming them.
As per an alternative characteristic, the width of the second strip is identical to that of the first strip. In this case, the hems are formed with two layers, which reinforces them mechanically.
As per an improvement, the system with at least one reinforcement panel comprises a single panel that extends over the first and second flaps.
As per an accomplishment mode, two reinforcement panels are successively cut and placed, one on the first flap and the other on the second flap leaving a gap between them at the level of the folding crease. We thus obtain a bag with two reinforcement panels separated at the level of the folding crease.
As per an improvement, using a third means of adhesive application downstream of the intake means and upstream of the cheek formation station, adhesive is applied to each bellows cheek or to the central part of the flaps in the corner areas that extend, after formation of the bag, to the corners of the central part of the flaps between the folding crease and the marking lines on said flaps. After the formation of the cheeks, they are folded onto the central part of the flaps, which makes it possible to obtain the bonding of the corner areas.
As per an improvement, the hem is also bonded to the face opposite the seam face along just one of the elements among the first and second flaps. Thus, considering one of the edges of the manufactured bag, the two hems are superposed and bonded to each other and, in addition, just one of them is bonded to the cheek where applicable, or to the internal face of the flap. It can be seen that this arrangement makes it possible to stress the adhesion essentially sliding one hem over the other, whereas without bonding, the constraint is concentrated on the edge of the bonded area and tears the bond more easily.
The object of the invention is also a machine for manufacturing a bag made of flexible material:
As per an improvement, the machine also comprises a third means of adhesive application downstream of the intake means and upstream of the cheek formation station, to apply adhesive to each bellows cheek or to the central part of the flaps in the corner areas that extend, after formation of the bag, to the corners of the central part of the flaps between the folding crease and the marking lines on said flaps.
The invention will be better understood and other features and advantages will appear on reading the following description, the description referring to the attached drawings among which:
A bag 1 envelope as per the invention's first accomplishment mode is shown in
The bag 1, shown in the deployed position in [
As shown in the transverse sectional view of [
In a variant shown in
A machine 2 as per a first accomplishment mode of the invention enabling the manufacture of bags is shown schematically in [
Optionally, the machine 2 may comprise a third means of adhesive application 33, downstream of the intake means 24 and upstream of the cheek formation station 31, to apply adhesive to each bellows cheek 181 or to the central part 110 of the flaps in the corner areas 10 that extend, after bag formation, to the corners of the central part 110 of the flaps between the folding crease 13 and the marking lines 17 on said flaps 11, 12
Optionally, the machine comprises another hemmer 252 for making a hem 15 on the edges of the second strip 1b in the case where the second strip 1b is wider than the first strip 1a and where the hems 15 are only supported by the second strip 1b.
The first, second and third adhesive application means 211, 212, 33 are, for example, flexographic rollers making it possible to apply adhesive according to a predetermined pattern. For the first and second application means, the adhesive is applied on the internal face 14 of the strip, that is to say on the face opposite the other strip after assembly. The third application means 33 is placed downstream of the intake means, because the exposed adhesive would make the adhesive-coated surface stick to the rollers of the intake means 33. However, it could be considered that the third adhesive application means 33 could be placed upstream of the intake means 33 if the latter comprises circular grooves allowing the adhesive-coated areas 10 to pass.
The intake means 24 is made with a pair of contra-rotary rollers 241 driven by a motor, not shown. They apply a pressure to the strips 1a, 1b to obtain bonding between them and to the reinforcement panels 19a, 19b.
The feed means 22 also comprises intake means 221 for bringing together two reinforcement strips, then the second cutting means 220 for cutting the reinforcement strips assembled into panels 19a, 19b, as detailed below.
The transport means 26 should preferably be means functioning by suction so as not apply any forces through the thickness of the assembly.
The application means 27 shall, for example, be nozzles injecting adhesive intermittently.
The first cutting means 28 and the folding means 29 are conventional and are not described here. The machine's various parts are driven in rotation either by the same motor and synchronous mechanical transmissions such as cog belts or gears, or by several individual electronically synchronised motors, or a combination of the two solutions.
The intake means 221 of the feed means 22 takes two layers of reinforcement and superposes them, the layer on the first strip 1a side being wider than the other one. The second cutting means 220 cuts a first part of the reinforcement panel 19a1, 19b1 which will extend over the first flap 11, then a second part of the reinforcement panel 19a2, 19b2 which will extend over the second flap 12. A small gap is created between the first and second parts of the system of reinforcement panels 19 in order to allow the easy creation of the folding crease 13. The intake means 221 of the feed means 22 slows down the reinforcement strip feed to allow the creation of a gap on the second flap 12 between the second part of the panel and the first part of the next section. The reinforcement panels 19 only extend over the central part 110 of the first strip 1a, and therefore not over the cheeks 181. In the first accomplishment mode, which is presented here, each part of the reinforcement panel 19 extends between the future folding crease 13 and a future marking line 17. All of the first strip 1a is covered by the second strip 1b over the panel system 19 to form an assembly of strips after passing through the intake means 24. The application of adhesive to the second strip 1b allows it to be bonded to the narrowest reinforcement panel, in the areas of the reinforcement panel not covered by the previous one and to the first strip 1a.
Downstream of the intake means 24, the assembly of strips passes through the cheek formation station 30 in which the cheeks 181 are folded against the second strip 1b. The hem 15 becomes visible again from the top, when looking at the internal face 14 of the bag. After folding the cheek 181 against the internal face 14, the latter extends between the hem 15 and a central part 110 of the strip, in such a way that a stack is formed with, in the following order, the central part 110, the cheek 181 and the hem 15.
The visible face of the hems 15, also called seam face 150, is coated with adhesive over the same lengths on both sides of the future folding crease 13 by the application means 27, then the assembly of strips is cut by the first cutting means 28 into sections T, at the level of the cutting line 111. The sections T are transferred to the folding means 29 which forms the folding crease 13 and folds the first flap 11 onto the second flap 12. The hems 15 of the first flap 11 then adhere to the hems 15 of the second flap 12 and the bag 1 is formed, as shown in [
When opening the bag, by separating the flaps 11, 12 and deploying the bellows 18, the bonded part of the cheeks remains linked to the central part 110 between the marking lines 17 on the corner areas 10, which facilitates the formation of the rectangular-shaped bottom.
In a variant, not shown, the corner areas 10 along the same cheek on both sides of the folding crease 13 can be brought together.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR2105064 | May 2021 | FR | national |
| FR2105765 | Jun 2021 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/062438 | 5/9/2022 | WO |
