Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D51/00—Making hollow objects
  • B21D51/16—Making hollow objects characterised by the use of the objects
  • B21D51/26—Making hollow objects characterised by the use of the objects cans or tins; Closing same in a permanent manner
  • B21D51/30—Folding the circumferential seam
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D51/00—Making hollow objects
  • B21D51/16—Making hollow objects characterised by the use of the objects
  • B21D51/26—Making hollow objects characterised by the use of the objects cans or tins; Closing same in a permanent manner
  • B21D51/2646—Of particular non cylindrical shape, e.g. conical, rectangular, polygonal, bulged
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D51/00—Making hollow objects
  • B21D51/16—Making hollow objects characterised by the use of the objects
  • B21D51/26—Making hollow objects characterised by the use of the objects cans or tins; Closing same in a permanent manner
  • B21D51/2653—Methods or machines for closing cans by applying caps or bottoms
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D51/00—Making hollow objects
  • B21D51/16—Making hollow objects characterised by the use of the objects
  • B21D51/26—Making hollow objects characterised by the use of the objects cans or tins; Closing same in a permanent manner
  • B21D51/2684—Cans or tins having circumferential side seams
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D51/00—Making hollow objects
  • B21D51/16—Making hollow objects characterised by the use of the objects
  • B21D51/38—Making inlet or outlet arrangements of cans, tins, baths, bottles, or other vessels; Making can ends; Making closures
  • B21D51/44—Making closures, e.g. caps
  • B21D51/443—Making closures, e.g. caps easily removable closures, e.g. by means of tear strips
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D53/00—Making other particular articles
  • B21D53/16—Making other particular articles rings, e.g. barrel hoops
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D17/00—Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions
  • B65D17/06—Integral, or permanently secured, end or side closures
  • B65D17/08—Closures secured by folding or rolling and pressing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D17/00—Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions
  • B65D17/28—Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions at lines or points of weakness
  • B65D17/401—Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions at lines or points of weakness characterised by having the line of weakness provided in an end wall
  • B65D17/4011—Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions at lines or points of weakness characterised by having the line of weakness provided in an end wall for opening completely by means of a tearing tab
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D7/00—Containers having bodies formed by interconnecting or uniting two or more rigid, or substantially rigid, components made wholly or mainly of metal
  • B65D7/12—Containers having bodies formed by interconnecting or uniting two or more rigid, or substantially rigid, components made wholly or mainly of metal characterised by wall construction or by connections between walls
  • B65D7/34—Containers having bodies formed by interconnecting or uniting two or more rigid, or substantially rigid, components made wholly or mainly of metal characterised by wall construction or by connections between walls with permanent connections between walls
  • B65D7/36—Containers having bodies formed by interconnecting or uniting two or more rigid, or substantially rigid, components made wholly or mainly of metal characterised by wall construction or by connections between walls with permanent connections between walls formed by rolling, or by rolling and pressing

Definitions

• the field of the invention is that of the food industry.
• the invention relates more particularly to containers intended for storing food for a long time, and in particular to cans.
• Metal cans allow the food they contain to be stored for a long time. They are made of a metallic body, and differ in the way they are closed.
• Some cans are closed by two rigid metal bases which are generally secured to the body by crimping to make a sealed container.
• Such a closing process makes it possible to subject the food products contained in these boxes, once the latter are closed, a heat treatment at high temperature, in particular at a temperature above 110 ° C (sterilization), in order to guarantee a conservation of several months at room temperature.
• These boxes can have difficulty opening, due to the importance of the thickness of the metal bottom, in order to withstand variations in internal pressure.
• This system uses, on one of the two metal bases, a gripping ring allowing the opening of a part of the metal base, previously weakened (by an incision, for example). It is by far the most widespread system and still in constant progression. In 2007, 86% of cans were equipped with easy opening (the rate was 77% in 2002). Peelable opening: by pulling on the tab, a heat-sealed aluminum cap peels off from the box to offer full opening.
• This system is mainly used for nomadic products (salads, desserts.), But is not suitable for boxes that have to undergo sterilization, excluding external backpressure, because the force required (the opening force (initial pulling force ) is generally of the order of 20 N, but generally less than 28 N) to take off the cap is lower than that exerted by the internal overpressure observed during sterilization. Thus, if it is desired to sterilize such boxes, the conditions to be implemented are technically more complicated and more expensive.
• tin can which has an easy opening, which makes it possible to reduce the needs and costs of raw materials, which guarantees good resistance to pressure variations during sterilization and optimum sealing of the can, and which allows simple and inexpensive manufacture which can be used by canning companies while keeping existing processes as much as possible.
• US2386312A1 describes methods for attaching bottoms to drums. These backgrounds do not appear flexible: indeed, even if they can be deformed, they do not return to their original shape after deformation (col. 2, lines 13-19 of US2386312A1).
• GB159188A relates to closing barrels and describes one way of creating a crimping element that can fit snugly to the barrel. It is not indicated that the funds used are flexible, which does not appear to be relevant in view of the field of application (large metal barrels (see p.1, col. 1, lines 8-9)) .
• WO003051725A1 discloses a container such as a soft drink can, comprising an upwardly open metal body having a side wall with an annular top portion having a reduced diameter neck formed therein, and a metal top structure such as a cover having an annular portion integral with the annular upper portion of the side wall along an annular seal extending outwardly and substantially horizontally or downward from the side wall.
• a metal top structure such as a cover having an annular portion integral with the annular upper portion of the side wall along an annular seal extending outwardly and substantially horizontally or downward from the side wall.
• GB286364A describes the application of bottoms to containers by crimping.
• GB698957A describes methods for improving crimping on containers.
• the present application proposes a solution making it possible to use existing crimping tools, without introducing any significant change in the practices of closing the boxes. It also makes it possible to work on containers whose diameters or opening dimensions are not imposed by market standards linked to the manufacturing processes of conventionally used bottoms.
• the methods used in the art indeed require the use of standard box formats, linked to the press tools used in the manufacture of funds. In fact, the current methods of manufacturing funds are restrictive as to the size of the boxes, or their shape.
• the present application thus aims to present a system for placing a base on a tin can, ensuring tightness if the can is to be sterilized, and reducing material loss.
• This bottom is preferably a flexible bottom. It may or may not be peelable.
• a flexible bottom is able to deform (bulge), passively, during sterilization (increase in internal pressure), and to regain the initial shape, without showing cracks or deterioration, when the internal pressure drops when the box temperature drops after sterilization.
• the flexible bottom exhibits an absence of irreversible mechanical deformation unlike a conventional metal bottom which may exhibit irreversible deformation depending on the force applied. In general, this flexibility is accompanied by lower overall resistance of the soft bottom.
• the invention thus relates to a method of manufacturing a tin can, characterized in that it comprises the step of placing a bottom at one end of the body of the tin can, said bottom being fixed to the tin can. body by the intermediary of a retaining ring (or crimping) crimped at the end of the box body, characterized in that the retaining ring is a welded ring.
• a ring which can be made of any diameter or shape, as well as a bottom cut from a flexible sheet makes it possible to no longer be constrained as to shape or size large containers.
• the top diameter of the cans can be increased beyond the largest diameter generally observed (153 mm).
• special commercial operations can be programmed with small series of boxes of different shapes or sizes. You can also easily prepare boxes whose bottoms will not be the same size or shape.
• the crimping ring is therefore a welded ring, that is to say it has a weld line. This weld line maintains the shape of this ring.
• the crimping ring is preferably obtained by welding the ends of a metal strip (having the length of the box perimeter) in order to close it. It should therefore be noted that, in the context of the envisaged use, the ring may be circular in shape or any other shape, depending on the shape of the tin can.
• the crimping ring is not obtained by hollowing out a sheet of metal.
• a welded ring is used obtained by welding a metal strip, as described above, then folding said strip to form a groove.
• This groove is thus positioned opposite the end of the body of the box during the crimping step.
• the end of the tin can body is then inserted into the groove and the edges of the groove are then strongly pressed / tightened against the body to ensure a perfect fit.
• the welded ring also has a flat directed towards the inside of the ring.
• This flat area (generally a few millimeters in width) therefore creates a flat surface all around the perimeter of the tin can.
• This flat surface can be used to attach a peelable bottom, or to stretch a flexible non-peelable bottom, fixed between the box body and the welded crimp ring fitted with the flat.
• the bottom is formed by a flexible sheet.
• the invention also relates to the use of a welded ring for fixing a base to a container, in particular a tin can body by crimping the ring welded to one end of the container or to the body of the container. container, said bottom becoming integral with the container after crimping.
• the backing is directly attached to the welded ring (this is the case, for example, when the backing is peelable).
• the bottom is trapped / wedged between the wall of the container and the crimping ring and becomes integral when the pressure applied to the hemlines of the ring crimp the latter to the body of the container.
• this background is a peelable background. It is then a cover sealed on the flat part of the crimping ring.
• This seal is formed with materials known in the art, including aluminum, thermoplastic polymers.
• This peelable background can be formed from one or more layers, identical or different. Methods for sealing the bottom to the land are known in the art. Mention may in particular be made of heat sealing.
• a tab is attached to the bottom, allowing the lid (bottom) to peel off the flat.
• this peelable bottom is attached to the crimping ring before positioning the ring on the body of the box and closing the latter.
• the background is not peelable.
• the bottom is formed by a flexible sheet with a surface slightly greater than the surface determined by the end of the metal body of the tin can.
• this flexible sheet has the same shape as the end of the metal body, but slightly larger dimensions in each of the dimensions (a slightly larger radius if the end of the metal body is circular, a greater length and width if the end of the metal body is rectangular ).
• the flexible sheet is wedged between the metal body and the crimping ring and is thus retained in a sealed manner during the crimping of the ring on the metal body, which thus serves to fix the base on the container and to close it. this.
• the flat preferably present on the crimping ring serves to stretch the flexible film closing off the end of the box, as well as to protect this flexible film (forming a flexible base) during the transfer or stacking of the boxes.
• the first fragility of the film is indeed around the box body.
• the film used to close the box is in the form of a roll, a little wider than the width of the box.
• non-peelable bottom When it is desired to use a non-peelable bottom, it can also be fixed on the flat, according to the methods described in WO2016139341, then crimp the ring carrying the non-peelable bottom thus fixed to the body of the container. Opening the box
• the flexible sheet has a pre-cut portion useful to facilitate opening of the box.
• This pre-cut part consists of a partial incision, forming a break line, of said flexible sheet (while maintaining air tightness).
• this partial incision weakens the sheet along the line of rupture.
• a tongue or a small gripping ring can be glued, on the flexible bottom, and close to the precut zone, which can be pulled by the end user, in order to induce the rupture of the zone. of fragility, and thus improve the opening of the box.
• the bottom is not peelable, but the opening system (pulling a tab inducing rupture of the bottom and opening of the box) is similar to the system known by consumers for peelable bases.
• the opening can be made, for example with the help of a knife or a spoon, by exerting pressure at the point of the rupture line.
• this break line having the precut is also associated with a visual marking.
• the precut can be done on an ink pre-marking or the ink premarking can be added after the precut step. This allows the consumer to better visualize the precut compared to the rest of the bottom of the box.
• the hygienic conditions related to the use of the can opener are not always optimal, because this tool penetrates inside the container, with a risk of coming into contact with the contents and of contamination. of it.
• the use of a can opener can lead to the introduction of iron filings in the contents.
• the lid opened with a can opener has some dangerous roughness.
• said flexible sheet comprises at least one gas impermeable layer.
• said flexible sheet comprises at least one metallic layer.
• this layer can be made of aluminum.
• This metallic layer is particularly useful for serving as a gas-tight barrier.
• said flexible sheet comprises at least one layer of plastic material. This is particularly advantageous for ensuring, for a reduced thickness, sufficient strength of the flexible sheet so as to resist the deformations which take place during the heat treatment of the tin can.
• said flexible sheet comprises at least one layer of plastic material of plant origin.
• said flexible sheet is formed from a single layer.
• said flexible sheet is formed of several layers.
• Such multi-layered sheets are known in the art and can be obtained by known methods, such as lamination.
• the flexible sheet has a gas-impermeable layer (in particular metallic) and is covered on at least one face by a plastic layer.
• the flexible sheet thus contains at least one layer permitting gas tightness, and air tightness in particular. It is in fact necessary to avoid the entry of oxygen liable to oxidize the products (in particular food) contained inside the can.
• this layer can be metallic.
• Aluminum is a preferred metal in that it is easily malleable and can be rolled into flexible sheets.
• a metal layer in particular aluminum
• Synthetic polymers such as polyamide films can also be used as a gas barrier layer. The thicknesses of these polymer films are in the same ranges as those of the metallic films mentioned above.
• the flexible sheet has a gas-tight layer (in particular oxygen) which is covered on at least one side by a plastic layer, and preferably on both sides.
• a gas-tight layer in particular oxygen
• the inner layer (layer inside the box after fixing the bottom) is very preferably formed with a polymer suitable for food contact. In fact, this internal layer will come into contact with the food contained in the box, in particular during sterilization and / or handling of the box. This layer should also preferably have good physical resistance including at sterilization temperatures in the event that such a step is envisaged.
• Any plastic or polymeric film suitable for contact with food can be chosen, in particular of the polyethylene type, but polypropylene having better physical resistance and better temperature resistance than polyethylene is preferred for this application. Homo polypropylene (PPH) or copolymer polypropylene (PPC) can be used.
• the thickness of the inner layer is generally between 35 and 55 microns, in particular between 40 and 50 microns. We can thus use a layer of thickness of about (or of) 45 microns.
• the outer layer particularly suitably has good resistance, in particular to abrasion to avoid the risk of tearing during handling.
• Polyethylene type polymers are preferably used, such as low density polyethylene, high density polyethylene, or polyethylene terephthalate (PET).
• PET polyethylene terephthalate
• Other polymers polyethylene oxide, polycarbonate, polymethyl methacrylate
• the thickness of the outer layer, especially when formed from polyethylene, is in the order of 17-25 microns.
• the cover formed from a flexible sheet therefore has a thickness of between 100 and 150 microns, generally between 120 and 150 microns. However, the thicknesses indicated above can be doubled if one seeks a increase in properties. Sterilization temperatures are generally of the order of 125 to 130 ° C.
• the flexible sheet (flexible film) multilayer is obtained in a conventional manner in the art by lamination or gluing of the inner and outer layers on the central layer, or of a gas-impermeable layer (in particular metallic) on the outer layer (polyethylene ) followed by addition of the polymer forming the inner layer.
• Type of tin can
• the body of the tin can is of the stamped or stamped-drawn type.
• stamping for the manufacture of the metal body is that it is formed in one piece, and does not present any welding (unlike three-piece boxes whose body is formed by welding of a metal side). This avoids crimping two weld areas which could potentially turn out to be areas of leaks, loss of tightness and lead to potential contamination.
• Shape of the tin can be any shape of the tin.
• the advantage of the proposed method is that the size and shape of the funds (and therefore of the boxes) is free and is no longer imposed by the usual standards for the manufacture of the funds. Thus, we can consider boxes of any shape.
• the end of the body of the tin can is circular in shape.
• the end of the tin can body is rectangular or square in shape. It usually has rounded corners.
• the end of the tin can body is oval shaped.
• the can body is in the form of bowls.
• the can bodies can be stacked before filling or after use.
• the invention relates to a method of placing a base on the body of a tin can, comprising the steps of (a) Provide a tin can body at the end of which a bottom is to be attached,
• the projected area of the flexible sheet is slightly larger than that of the end of the can body.
• flexible sheets as described above are used. They may in particular contain at least one layer impermeable to gases (in particular metallic), and preferably at least one plastic layer on one of its faces.
• the above method is preferably carried out continuously.
• the method may also include one or more of the following steps, carried out before or after the step indicated above: a step of filling the metal body with one or more food products; a step of crimping a rigid bottom on the other end of the metal body so as to hermetically seal the box;
• one end of the body is closed with a rigid bottom as known in the art
• the box is subjected to sterilization.
• one end of the box body is closed with a flexible bottom, attached to the box via a crimping ring, said ring being a welded ring, according to the methods described above
• the box is subjected to sterilization.
• one end of the box body is closed with a flexible bottom, attached to the box via a crimping ring, said ring being a welded ring, according to the methods described above
• the second end of the body is closed with a flexible bottom, attached to the box via a crimping ring, said ring being a welded ring, according to the methods described above
• the box is subjected to sterilization.
• a closed tin can body (cylinder) is provided, at one of its ends with a rigid bottom as known in the art
• the second end of the body is closed with a flexible bottom, attached to the box via a crimping ring, said ring being a welded ring, according to the methods described above
• the box is subjected to sterilization.
• the second end of the body is closed with a flexible bottom, attached to the box by means of a crimping ring, said ring being a welded ring, according to the methods described above
• the box is subjected to sterilization.
• the flexible bottom in (a) can be attached to the body of the box by means of a crimping ring, said ring being a welded ring, according to the methods described above, or by any other method known in the art such as that described in WO2016139341.
• the projected area of the flexible sheet is slightly larger than that of the end of the can body. If the box is of the stamped type, the filling of the metal body is carried out before the steps of closing the box by crimping, as described above.
• the above methods may also include a step of heat treatment (sterilization) of the tin can sealed at both ends.
• the manufacturing method also comprises a step of precutting the bottom (preferably flexible) attached to the box via the (welded) crimping ring in order to allow easy opening of the crimping ring. the box.
• This precut preferably occurs after the heat treatment since the latter causes high pressure stresses and it is therefore preferable that the bottom (preferably flexible) is not weakened.
• the invention also relates to a method of sterilizing a tin can as described above, comprising a step of placing said can under temperature and pressure conditions inducing internal suppression (in said can) d 'at least 0.8 bar (or any other value as indicated above).
• said box is subjected to the overpressure for at least 2 minutes (or any other duration indicated above, a preferred duration being greater than or equal to 6 minutes, or 7 minutes).
• the invention thus relates to a method of manufacturing a tin can as described above comprising: a step of crimping a first flexible base on the lower part of the metal body by means of a welded ring; a step of filling the metal body with one or more food products; a step of crimping a second flexible bottom on the upper part of the metal body, via a crimping ring (preferably welded) so as to hermetically close the box; possibly a step of heat treatment (sterilization) of the tin can.
• the manufacturing process comprises a step of precutting at least one of the two flexible bases in order to allow easy opening of the box.
• This precutting takes place preferably after the heat treatment since the latter causes high pressure stresses and it is therefore preferable that the flexible bottom is not weakened.
• Such a manufacturing process can be implemented efficiently, on an industrial scale.
• the invention in another aspect, relates to a container having at least one bottom formed by a flexible sheet, said flexible sheet being fixed to one end of the container by crimping on the body of the container by means of a welded ring.
• the invention thus relates to a container having a metallic body and at least one end of the metallic body closed by a bottom comprising a flexible sheet, the flexible sheet being held on the metallic body. by means of a ring crimped on the metal body, characterized in that said ring is a welded ring.
• the flexible bottom can be attached to the crimping ring (for example on a flat part of this ring), especially when the bottom is peelable.
• the flexible bottom is wedged between the metal body and the crimping ring, a tight closure of the container being obtained when crimping the ring on the metal body of the container.
• the flexible bottom has a pre-cut part.
• the container may include two flexible bottoms, at least one of which is secured via a welded crimp ring.
• the two flexible bottoms are fixed by means of a crimping ring, of which at least one of the two is welded. More preferably, the two crimp rings are welded rings.
• the container has an internal depression with respect to atmospheric pressure.
• the container is of the tin can type. It is illustrated that cans (in Europe) are generally of types as described in Table 1.
• the tin can is of the stamped or stamped-drawn type.
• the plastic polymer layer can be printed, eliminating the need for labels on the body of the boxes. It is also possible to use transparent films making it possible to see the ingredients contained in the containers.
• the invention is particularly advantageous in the case of fish canning (such as cans of sardines).
• the boxes are rectangular in shape, the easy-opening bodies and bottoms being made of aluminum.
• Aluminum is generally more expensive than steel for the same box, but steel easy-open lids cannot be used on these. cans of canned fish, due to their rectangular shape. Indeed, the force required to open the box (break the rigid cover by pulling on the ring) is too great and the shape memory properties of the steel (tendency to go back when pulled on) complicate the opening capacity of a steel bottom for these boxes.
• Aluminum is therefore used for these types of boxes because this material is softer than steel and therefore has better workability.
• An aluminum box body must then also be used because the use of a steel body leads to risks of galvanic corrosion.
• crimping makes it possible to obtain a good seal, by a process that is simpler to implement than that described in WO2016139341.
• crimping is well known, used and mastered in the art (method used to fix rigid bottoms) and is known to ensure a good seal.
• crimping involves a tightening operation, which, once carried out on metal, provides a link, tight against gases and against microorganisms, between the bottom and the body of the box.
• the mechanical strength will also be improved compared to WO2016139341, which may require the installation of hems protecting the sealing zone of the flexible film on the mechanical body.
• the boxes exhibit the same type of mechanical strength, as a whole, as the hard bottom boxes of the prior art. This allows good protection during logistical operations (transfers and handling of boxes).
• Figure 1 a welded ring (1) before shaping.
• the weld line (11) obtained when closing the ring is also indicated.
• Figure 2 View of a section of a welded retaining ring (1) usable to be crimped on a body of a container. We see the groove (12) intended to be introduced on the end of the body of the container, as well as the flat (13) which is directed towards the inside of the welded ring.
• Figure 3 top view of a welded ring of circular shape according to the invention. We observe the weld line (11) as well as the flat (13).
• Figure 4 diagram of the method of closing a box (3) according to the invention by means of a flexible bottom (2) which will be fixed by crimping between the body (3) of the box and the ring ( 1) retained. We observe the weld line (11).
• Figure 5 Top view of a closed tin can, with the presence of an opening tab (22) and a line of weakness (21) to allow the flexible bottom to break.
• the rings are circular.
• the shape of the ring is the same as that of this end.
• Example 1 Manufacture of a crimping ring for a 4/4 box
• a welded ring is made for crimping on a 4/4 box. This box has a diameter of 99 mm.
• a strip of about 9 to 11mm in width and 99-101mm in length is cut from a sheet of steel, 0.20 to 0.24 thick, in particular between 0.21 and 0.23 mm.
• This steel strip is folded back and its ends are welded. It is possible to use an industrial welder such as that marketed by Soudronic (Bergdietikon, Switzerland). This gives a welded ring, similar to that described in Figure 1, with a useful diameter of 99 mm for the hemmed area.
• the ring is then shaped to give it the shape shown in Figures 2 and 3.
• the inverted U-ring is folded to form a groove (12), and also forms a flat (13).
• Apparatus known in the art such as a "curler” moulder, can be used.
• a steel is used having a suitable malleability (steel grade adapted to the radius of the box) in order to allow the formation of the folds (of the groove) necessary for the crimping.
• the welded ring (1) is thus successively composed (from the outside to the inside) of a hemmed (121) (crimping zone), a cup (122) (hemmed return) then of a flat (13).
• the hemmed (121) and hemmed return (122) have a development of about 6 to 7 mm and form the groove (12).
• a steel strip of approximately 9 to 11 mm useful width will therefore make it possible to form a welded ring for a box with a diameter of 99 mm.
• a flexible bottom (2) is provided which may have been cut from a reel of film and which has the same shape as the box body (3) and the crimping ring (1), but slightly larger dimensions (here a diameter).
• the ring (1) is lowered onto the end of the body (3) so as to trap the bottom (2) between the ring (1) and the body (3) then the crimping is carried out by pressure on the two hemlines (121) and (122) forming a groove (12).
• the presence of the flat (13) helps to tension the flexible bottom (2) during the assembly step.
• a ring (1) as obtained according to Example 1 is used.
• a peelable base is attached to this ring according to methods known in the art for fixing peelable bases on rings obtained by hollowing out material.
• the ring bearing the peelable bottom is then assembled on the body of a box by crimping according to methods known in the art.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Rigid Containers With Two Or More Constituent Elements (AREA)
• Packages (AREA)

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Publications (1)

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• 2019
  • 2019-10-14 FR FR1911383A patent/FR3101861B1/fr active Active
• 2020
  • 2020-10-13 WO PCT/EP2020/078705 patent/WO2021074110A1/fr not_active Ceased
  • 2020-10-13 EP EP20792601.5A patent/EP4045207A1/de not_active Withdrawn
  • 2020-10-13 US US17/768,541 patent/US20240109119A1/en not_active Abandoned

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