WO2005061149A2

WO2005061149A2 - A method and an installation for forming a metal container and a metal container for storing of foodstuff

Info

Publication number: WO2005061149A2
Application number: PCT/DK2004/000897
Authority: WO
Inventors: Jens Jørgen PEDERSEN; John Thomsen; Stig Rasmussen
Original assignee: Glud & Marstrand A/S
Priority date: 2003-12-22
Filing date: 2004-12-22
Publication date: 2005-07-07
Also published as: WO2005061149A3

Abstract

A method and installation for forming a metal container. The method comprises placing an elastic deformable member (17) inside the container (1), and the member (17) is deformed in said container (1) such that the member expands towards a part of a sidewall of the container (1) and allowing said part to expand unhindered so as to form the container into the shape of at least a part of said member (17) when the member (17) is expanded.

Description

A METHOD AND AN INSTALLATION FOR FORMING A METAL CONTAINER AND A METAL CONTAINER FOR STORING OF FOODSTUFF

The invention relates to a method and an installation for forming a metal container by expanding the sidewall thereof so as to provide one or more outwardly extending projections in its wall, such as convex shaped parts.

Background of the invention

It is known to expand containers into an outer shape, such as a convex shape, for increasing the volume and for giving the container a more attractive look.

US 3,807,209 discloses a can body shaper for outwardly expanding the same to a decorative predetermined contour. The can body is shaped in a tool pack carrying an expendable membrane receivable within the can body and two molder halves are closeable about the can body and cooperates with the tool pack. Thus, the can body is shaped by pressing its sidewall towards the molder halves.

US 3,698,337 discloses a method of forming a wall of a non-flanged cylindrical body A tubular elastomenc member is positioned within a die-contained can body and is pressurised towards the die to mold the can body to the shape of the die.

US 3,222,902 discloses a method for shaping workpieces of deformable material. The shaping is provided in a forming die, and wherein an elastomenc member is inserted into a container body, the member defining a container containing an energy transmitting medium. A shock wave is created in the medium by means of electrodes, and the shock wave transmits energy to the elastomenc member for shaping said container body to the contour of the die.

The can bodies according to the above mentioned methods are all shaped by use of an expandable member being expanded towards a mold or tool, such that the can body is formed by the contour of an outer mold or tool. However, use of an outer tool for shaping the can body is a very expensive and time consuming way of shaping can bodies, as the outer tool has to be opened and closed for shaping one can body which is very time consuming and as it is very expensive to produce said outer tool.

Thus, it is an object of the present invention to provide a more cost efficient, easier and less time consuming method and installation for forming a metal container, which is user-friendly, aesthetically attractive, having an increased volume, while still having the sufficient strength to protect the content

Description of the invention

According to a first aspect, the present invention relates to a method of forming a metal container, the method comprising placing an elastic deformable member inside said container and deforming said member so as to expand it towards a part of a sidewall of the container and allowing said part to expand unhindered so as to form said part into the shape of at least a part of said member when the member is expanded

Thus, the shaping of the sidewall is provided only by the deformable member and not by use of an outer tool, which then allows the sidewall to expand unhindered outwardly until it reaches the preferred shape defined by the shape of at least a part of the expanded deformable member.

As there is no outer tool which has to be closed and opened for each container to produce, the method is much faster than the above mentioned methods. This means that the method allows for production of up to around 8- 10,000 containers per hour per forming station of an installation, whereas the prior art methods normally only allows for production of 3,500-4,000 containers per hour.

The member may be adapted to provide a directional expansion/elastic deformation in a direction substantially perpendicular to a centre axis of the container. Preferably, the member is adapted to provide a convex formed part in the sidewall, but the member may be adapted to provide not only convex shapes but also a combination of convex and linear and/or circular shapes. In a particular embodiment, the member is adapted to provide a shape in the sidewall, which is substantially identical to the outer shape of a nut ("bolt and nut").

The method preferably further comprises, subsequently to the step of deforming,

- contracting the member,

- moving the container along the member at least a distance corresponding to the length of the member,

- repeating the step of deforming. Thus, two succeeding formed parts are provided in the sidewall by the same deformable member Instead of moving the container, the member may be moved along the container.

Said two succeeding formed parts may be provided by different deformable members, and the method may comprise, subsequently to the step of deforming,

- contracting the member, moving the container from the member, - placing another deformable member inside said container at a level above or below said previous formed part of the sidewall,

- repeating the step of deforming.

The member may be inflatable and deformed by pumping up said member with liquid or gas, but preferably the member is deformed by mechanical means. The mechanical means may comprise a piston affecting said member.

Preferably, the member is made of a compressible material, and most preferably the member comprises a cylinder made of rubber, which may be compressed in a direction parallel to the centre axis of the cylinder and thus expands radially. The outer diameter of the cylinder is adjusted such that the member may be slided into the container. The inner diameter of the container is preferably 73 mm or 99 mm, but of course the diameter and shape of the member may vary depending on the size and shape desired for the container. The diameter may vary between 50 mm and 300 mm.

The container may be given a convex form being symmetrical about a centre plane that is parallel and/or perpendicular to a centre axis of the container. As mentioned the deformable member is preferably cylindrical in its non-deformed state, and it may take any shape in its deformed state, such as substantially spherical and/or a nut-like shape.

By positioning the container on an appropriate support surface or fixture, it is possible to adjust the deformation. Thus, it is possible to obtain a larger or smaller convexity. Further, by use of an elastic deformable member having different elasticity in different directions, it is possible to produce a container, which is symmetrical or asymmetrical in its e.g. convex form. Thus, it is possible to produce a container, where e.g. the convex form provides largest diameter near the top or bottom or middle of the container.

The elastic deformation is preferably provided such that it is directional perpendicular to a centre axis of the cylindrical container. It that situation it is possible to produce a rotary symmetric container Such a rotary symmetric container is preferably provided such that it is also symmetric about a centre plane parallel to the centre axis of the cylindrical container

Upon production of the container, the member can easily be removed as the member, due to its elastic deformation properties, will return to its original form and thereby be removed through the opening in the container.

After forming the sidewall of the container, the container may be provided with a lid. The lid may be produced by any kind of traditional production method.

As the deformable member preferably is made of rubber, it is very cheap to manufacture and thus provides much lower production costs than the prior art methods where an outer metal tool is needed, which is very expensive to produce. Due to the low cost, the manufacturer can develop and produce a lot of different deformable members for different container designs with low production cost.

Furthermore, the time used for conversion between different container production is minimal, as only the deformable member, such as a cylindrical rubber block, need to be replaced in the installation producing the containers.

However, it is of course possible to provide an outer tool around the container against which the member presses the sidewall. This is particular useful, if the container must be provided with projections or any kind of relief pressed into the sidewall, such as convex formed parts and one or more reliefs extending inwardly in said convex part. The outer tool may be a cylinder arranged around the sidewall of the container.

Thus, the present invention provides a more cost efficient, careful, easier and less time consuming method of producing a metal container, which is aesthetically attractive, has an increased volume in relation to the non-formed container and sufficient strength to protect the content. By use of this method it is possible, in an easy way, to provide a permanent deformation of the wall of the container.

According to a second aspect, the present invention relates to a method of producing a metal container with one or more outwardly extending projections in the sidewall, the method comprising : providing a container with a bottom part and a sidewall extending from said bottom part, placing an elastic deformable member inside said container, applying a force to said member for providing said elastic deformation of said member so as to press at least a part of said sidewall part outwards by said member and allowing said sidewall to expand unhindered for providing said one or more projections, and releasing said force.

The deformable member is preferably an expandable member of the method according to the first aspect, and the method according to the second aspect may comprise any of the features and steps according to the method of the first aspect.

According to a third aspect, the present invention relates to a metal container formed by a method according to the first and/or second aspect.

The container may comprise two or three or more succeeding convex formed parts along its height from the bottom to the top, and the formed parts may be located at any height level along the wall of the container.

The container may have not only convex shapes but also a combination of convex and linear and/or circular shapes. In a particular embodiment, the container may have a shape in the wall, which is substantially identical to the outer shape of a nut ("bolt and nut").

The container may have the same diameter at the bottom and top and a largest diameter at substantially half the height or at substantially 1/4 and 3/4 of the height, which diameter may be e.g. 201 mm.

The height of the container may be 50-250 mm, such as 62 mm.

The container may at the bottom and top have a diameter of between 50 mm and 200 mm, such as 73 mm or 99 mm or 190 mm.

The container is preferably made of tin, and the material thickness is preferably 0.15 mm, but the thickness may vary from 0.15 mm to 0.35 mm depending on the purpose for which the container is to be used.

The edges of the container may be curled to avoid sharp edges. In one advantageous embodiment of the invention, the formed container will have the same diameter at the bottom and the top and have a largest diameter halfway between bottom and top. Thus, a symmetrical convex curvature may be provided extending from the top to the bottom of the wall.

Any shape may of course be provided in the container, and the projections may be provided at any height along the container.

A specific advantageous container, e.g. intended to storage of 500 gram of cookies, will have a diameter in the bottom and top of 190 mm. The diameter halfway between bottom and top will be 201 mm. The container will have a height of 62 mm. Such a container may be produced from tin plate having a thickness of 0.15 mm.

Due to the reinforcement provided by formed parts in the sidewall, such as convex formed parts, in the wall, it is possible to reduce the material thickness without reducing the strength of the sidewall, and thus its impact resistance.

In an embodiment, the formed container may comprise two succeeding convex formed parts along its height from the bottom to the top. Thus, the formed container will have the same diameter at the bottom and the top and have a largest diameter 1/4 and 3/4 the height between bottom and top. Thus, two symmetrical convex curvatures are provided between the top to the bottom of the wall.

Of course, there may be provided more than two, such as three, four or five convex shaped parts along the height of the container, and each of the parts does not have to be symmetrical, but can be asymmetrical.

In its simplest form, the container comprises a substantially cylindrical body, which has been expanded along a length thereof to provide a greater volume, and/or conical or any other cylinder shapes.

According to a fourth aspect, the present invention relates to a metal can for storage of foodstuff, the can comprising a container having a substantially circular bottom part and a wall being attached thereto at its lower end, and a lid to be mounted to a top of the wall, the wall having at least one convex form between the bottom and top.

Said can may comprise any of the features mentioned in connection with the container according to the third aspect. Foodstuff may be stacked inside the can, and wherein the outer delimitation of the stacked foodstuff is within the diameter of the bottom part. As the sidewall is convex outwards in relation to the diameter of the bottom, an air space is provided between the sidewall and the stacked foodstuff. Thus, the risk of damaging the foodstuff, such as cookies, is minimised if the can is exposed to forces from outside causing indentations in the sidewall.

The container may comprise a bottom part and a cylindrical sidewall attached thereto and extending upwards therefrom, or it may be a container deep-drawn from a metal blank.

According to a fifth aspect, the present invention relates to an installation for forming a metal container,

the installation comprising; at least one forming station for forming said container, and conveyor means for conveying a plurality of containers to and from said forming station,

the forming station comprising; at least one deformable member to be positioned inside said container, means for moving said member into and out of said container, - means for expanding said member and allowing a part of a sidewall of the container to expand unhindered so as to form said part into the shape of at least a part of said member when expanded.

The expandable member preferably comprises any of the features mentioned in connection with the above aspects.

The conveyor means may comprise one or more worm conveyors and/or conveyor belts and/or carrousels and/or sledge-like conveyors.

In a preferred embodiment, the containers are conveyed to the forming station by means of a sledge-like conveyor moving one or two or more containers in succession from a storage area to the forming station. In another preferred embodiment, the forming station may comprise a rotating carrousel comprising a plurality of expandable deformable members, or a plurality of forming station may be provided in succession, so as to provide an installation for producing containers continuously and in an inline process

The means for expanding the member may comprise pneumatic and/or hydraulic and/or mechanical means.

Preferably, the means for moving said member comprises a piston attached to the member in its upper end and connected to a roller bearing (or wheel) in its lower end, a guide rail being in engagement with said roller bearing, the guide rail having a curved course in order to move the piston upwards and downwards upon rotation of said carrousel.

Preferably, the means for moving is also adapted to apply and release the force to/from said member so as to expand and retract the member when moving the piston upwards and downwards, respectively.

A piston may be attached to two expandable deformable members provided on top of each other so as to provide two formed parts in the sidewall of a container simultaneously, or there may be three or more deformable member on top of each other.

The installation may further comprise an outer tool to be positioned around the cylindrical wall of the container, and against which the cylindrical wall is pressed by said member, if inwardly extending die-stamps or embossments must be provided in the sidewall. However, the deformable member will still define the shape of sidewall, and the outer tool will only provide the die-stamps or embossments inwardly.

By forming the container according to the invention, the risk of indentations in the sidewall is reduced, as the container due to its e.g. convex form has a higher strength than a corresponding circular cylindrical container. The sidewall of the container will then have a relatively limited risk for formation of indentations.

Further, the formed part of the sidewall, e.g. the convex curvature, increases the strength of the container, which then results in that tin having a smaller thickness can be used, which then reduce resource consumption.

As the container has a curved shape that is aesthetic attractive, it is possible to serve the product directly from the decorated container. The container is also user-friendly, as it does not have any sharp edges or corners that may be inconvenient for example in relation to cleaning of the container.

The metal container may, after its initial use for transportation, storage and sale of foodstuff, be re-used for storage of other articles. The container may for example be used for storing cookies previously bought in a bag.

According to a sixth aspect, the present invention relates to an installation for producing a metal can with one or more outwardly extending projections in the wall of the can, the can comprising a bottom part and a substantially cylindrical wall attached thereto,

the installation comprising; at least one forming station for providing said projections in said wall, and - conveyor means for conveying a plurality of cans to and from said forming station,

the forming station comprising; at least one elastic deformable member to be positioned inside said cylindrical wall, - means for moving said member into and out of said wall, means for applying and releasing a force to/from said member, when the member is positioned inside said wall, for providing said elastic deformation of the member so as to press at least a part of said wall part outwards for providing said projectιon(s).

The elastic deformable member preferably comprise an expandable member according to the fifth aspect, the member being expanded when applying said force thereto.

The metal container according to the above aspects is preferably made of tin plate, but it may be made of aluminium or any other suitable metal type.

The container according to the above aspects is preferably used for transportation, storing and sale of foodstuff, which may be any kind of foodstuff, such as cookies, liver paste, refreshing drinks, beer, etc.

It should be understood that any combination of the features mentioned in connection with the aspects is possible within the scope of the present application.

The invention will now be described in details with reference to the accompanying schematic figures, wherein Fig. 1 shows a picture, partly in cross-section, of a container according to the invention,

Fig. 2-4 shows the step of a first embodiment of the method according to the invention,

Fig. 5-7 shows the step of a second embodiment of the method according to the invention,

Fig. 8 shows a member to be elastic deformed according to the invention,

Figs. 9- 10 show a metal container with a single convex curvature and a double convex curvature, respectively,

Fig. 11 shows a forming station for forming single convex curved containers according to the invention,

Fig. 12 shows a forming station for forming both single and double convex curved containers according to the invention,

Fig. 13 shows an installation for forming the containers according to the invention,

Figs. 14- 15 show an installation for forming both single and double convex curved containers according to the invention, and

Figs. 16a-c shows a deformable member according to the invention, and

Figs. 17a-c and 18a-c shows embodiments of containers formed according to the invention.

Fig. 1 shows a container 1 according to the invention. In the right part of the figure, the container is shown in cross-section and in the left part the container is shown in a side view. The container comprises a container 2 which is composed by a bottom 3 and a wall 4, which at its bottom is mounted to the bottom 3 by a curl portion 6. The metal container further comprises a lid 7, which is intended to attachment at the top 8 of the sidewall 4. The free edge of the lid 7 is provided with a curled part 9. The free edge of the sidewall is also provided as a curled part 10.

This container 1 is made of metal having a thickness of 0.15 mm. The container has a total height 11 of 62 mm. The sidewall 4 is made with a convex curvature 4a. At a centre plane 12 of the container 2 of the container is a diameter 12 of 201 mm At the bottom 5 and top 8 of the sidewall 4 is an identical diameter 14 of 190 mm The produced container thus has its largest diameter 13 at half height Further, the convexity of the sidewall 2 is symmetrical around a centre axis 15 of the container 1.

If the container is in use the cookies (not shown) are stacked with an outer delimitation being within the diameter 14 of the bottom 3. Thus, an air space 16 is provided along the circumference between the stacked cookies and the convex sidewall 2. Thereby, the risk of damaging the cookies is reduced.

Fig. 2-4 shows a first embodiment for producing a container 2 for a container according to the invention. In Fig. 2 is shown that a container is provided by a circular bottom 3 with a cylindrical wall 4 attached thereto. Within the cylindrical wall 4 is placed a deformable member 17. The deformable member has a hollowed inner part 18 being in connection with a filler plug 19. The filler plug 19 may be provided with a supply source for liquid or air 20 under pressure for pneumatic or hydraulic pumping of the member 17. A symmetric convexity is provided in the container as a symmetrical member used to form it. Thus, the cylindrical wall 4 is deformed as shown in Fig 3. The wall 4 is pressed outwards and takes the convex form.

In Fig. 4 is shown that the force applied on the member is removed as the liquid/air 21 is removed, and that the member 17 is drawn out of the formed container 2 after the elastic deformation has returned to the original diameter and thus can be drawn out in the direction of the arrow 22 through the opening 23 of the container.

Figs. 5-7 shows a further embodiment of a method for producing a container 2 with a convex formed sidewall 4. An elastic deformable member 24 is also used here. The member comprises a massive shell 25 and a hollowed interior 26. The member 24 is influenced mechanically by a piston 27, which is moved in the direction of the arrow 28 in order to provide a force, which provides an elastic deformation of the sidewall 4 as shown in Fig. 6. After ending the elastic deformation of the member 24, the piston 27 and the member 24 is removed from the container 2 in a direction according to the arrow 29. Also in this embodiment, the member may be easily removed from the interior of the container through the opening 23.

The forces on the wall provided by the elastic members 17,24 may happen in one or a plurality of operations depending on the size of the provided convexity. Fig 8 shows a member 17 to be elastic deformed. The member 17 is made of rubber 30 and having a through-going hole 31 for receiving a piston, shown on fig 13.

Fig. 9 shows a metal container 1 having a sidewall with a single convex curvature 4a, and fig. 10 shows a container having a sidewall with double convex curvature, i.e two curvatures 4a.

Fig. 11 shows a forming station for forming single convex curved containers according to the invention. The station comprises a conveyor 32 conveying the containers 1 to the carrousel 33 that transports the containers one by one to the forming carrousel 34. The carrousel 34 comprises a plurality of members 17 over which the containers are positioned and formed by elastic deformation of the member inside the containers. A further carrousel 35 is provided for transporting the formed containers away from carrousel 34 and to the conveyor 36 that transports the formed containers to a stock area.

Fig. 12 shows a forming station for forming both single and double convex curved containers 1. The containers 1 are fed to the forming stations by conveyors 32a and 32b. The conveyor 32a transports the containers 1 to the carrousel 37 which then transports the containers, one by one, to the forming station 17a wherein the containers are provided with a first convex curve in their sidewall. Subsequently, the containers 1 are transported to the carrousel 33 which brings them to the forming station 17b wherein the containers are provided with a second convex curve in their sidewall. Finally, the containers 1 are transported to the carrousel 35 and conveyed to a stock area by means of the conveyor 36.

The containers 1, to be formed with a single convex curve, are transported by the conveyor 32b to the carrousel 33 and further on to the forming station 17b wherein they are provided with the convex curve in their sidewall. Finally, they are transported to the carrousel 35 and to a stock area by means of the conveyor 36.

Each of the forming stations 17a, 17b, comprises a plurality of members 17 (positioned inside the containers 1 ) over which the containers 1 are positioned and formed by elastic deformation of the member inside the containers.

Fig. 13 shows an installation for forming the containers according to the invention. The installation comprises a conveyor 32 that transport containers to the forming station comprising members 17 for forming the convex curved sidewall of the containers. The members 17 are positioned in a carrousel driven by the motor 38 that is connected to the carrousel via the wheel 39.

Each of the members 17 is connected to a shaft 40, which is attached to an upper disc 5 41. The member 17 is thus positioned between said disc 41 and a lower flange 42. The shaft 40 is attached to a wheel 43 that runs in a guide rail 44 when the carrousel is driven around. The guide rail has a curved course going up and down in relation to the level of the containers positioned in the carrousel.

10 In the right side of Fig. 13, a container 1 is positioned over the member 17, when the member 17 is in its lowered position which is obtained when the wheel 43 is drawn downwards due to the a downwardly extending course of guide rail 44. When driving the carrousel around, the wheel 43 is pushed upwards due to an upwardly extending course of the guide rail 44, so that the member 17 is pushed into the container 1 When the

15 flange 45 contacts the stop 46, the disc 41 is at a level substantially equal to the inner side of the bottom of the container. Then the shaft is pushed further upwards so that the member 17 is compressed and elastic deformed in order to provide the convex form in the sidewall of the container Afterwards the shaft 40 is drawn downwards until the member is out of the container, and the container may be transported to a stock area.

20 Preferably, the guide rail is shaped such that the shaft 40 is drawn so much downwards, when retracting the member 17 from the container, that the member 17 is totally released from any compression forces, in order to avoid permanent force applied to the member, even when it is not in use. Thus, the member will last for a longer time.

25 Fig. 14 shows an installation for forming single convex curved containers. The containers 1 are positioned on the conveyor 32 that feeds the containers 1 to the sledge-like conveyor 37 comprising gripping claws 37a which grips succeeding containers 1 and moves them in step simultaneously to a orientation station 51. In each step the conveyor 30 37 moves the containers a length corresponding to two times the distance between two succeeding containers, such that the two containers that have been oriented are moved to each forming station in one step.

The orientation station 51 comprises two succeeding orientation pistons 52 that rotate 35 the containers into the correct position prior to entering the forming stations 17a, 17b. The welding in the sidewall of the container may for example be oriented in relation to the expanding process. When the two succeeding containers 1 are oriented correctly they are conveyed to the forming station 17a and 17b, where pistons 53 lift the containers up such that a deformable member 17 enters into the container. In the container the member 17 is deformed and expanded towards the sidewall of the container in order to form sidewall into the shape of the expanded member 17. When the containers 1 have been formed, they are moved to the conveyor 36 and transported to a stock area.

Fig 15 shows an installation almost identical to the forming station of fig. 14, but wherein double convex curved containers are formed. In this embodiment the sledge-like conveyor 37 moves the containers in step where the moving distance in each step correspond to the distance between two succeeding containers, as the forming stations 17a, 17b must provide an expansion in each container 1 for forming the double convex shape.

Figs. 16a-c shows a deformable expandable member according to the invention. The member 17 comprises a rubber block 30, which is adapted to be deformed by pressing the two flanges 54 towards each other. When pressing the member together it will expand radially outwards, and the expanded shape will be a nut-formed shape, as the concave portions 55 will expand out and define a substantially vertical sidewall of the member. The member 17 is used to provide the shape of a container according to figs. 17a-c.

Figs. 17a-c shows a container according to the invention having a substantially nut- formed shape with convex and linear parts 47, 48. The container may be provided by expanding one single member according to figs. 16a-c in the cylindrical body 56, and afterwards a bottom part 57 is seamed to an end of the body, and a lid 58 is positioned in the other end for closing the container

Figs. 18a-c shows another container according to the invention which has been provided by expanding a deformable member inside the cylindrical body 56. A bottom part 57 is seamed to an end of the body, and a lid 58 is closing the container.

The invention introduces a method and installation for shaping containers by use of only deformable expandable member(s) positioned inside the container and not any outer tool, which is a very cheap and easy way of shaping containers into a more attractive look while simultaneously increasing the volume. It should be understood that the invention provides a method and installation for forming containers into a lot of various shapes, and that the shapes shown in the figures only are examples.

Claims

1 A method of forming a metal container, the method comprising .

- placing an elastic deformable member inside said container, and deforming said member so as to expand it towards a part of a sidewall of the container and allowing said part to expand unhindered so as to form said part into the shape of at least a part of said member when the member is expanded.

2. A method according to claim 1, wherein the member is adapted to provide a directional expansion in a direction substantially perpendicular to a centre axis of the container.

3. A method according to claim 1 or 2, wherein member is adapted to provide a convex formed part in the sidewall.

4. A method according to any of claims 1-3, further comprising, subsequently to the step of deforming,

- contracting the member, moving the container along the member at least a distance corresponding to the length of the member, repeating the step of deforming.

5. A method according to any of claims 1-3, further comprising, subsequently to the step of deforming,

- contracting the member, moving the container from the member, - placing another deformable member inside said container at a level above or below said previous formed part of the sidewall, repeating the step of deforming,

6. A method according to any of claims 1-5, wherein the member is deformed by pumping up said member by means of liquid or gas.

7. A method according to any of claims 1-6, wherein the member is deformed by mechanical means.

8. A method according to any of the preceding claims, wherein the member is made of a compressible material, such as rubber

9. A method according to claim 7 or 8, wherein the mechanical means comprises a piston affecting said member.

10. A method according to any of the preceding claims, wherein the sidewall is given a convex form being symmetrical about a centre plane that is parallel and/or perpendicular to a centre axis of the container.

11. A method of producing a metal container with one or more outwardly extending projections in the sidewall, the method comprising : providing a container with a bottom part and a sidewall extending from said bottom part, placing an elastic deformable member inside said container, applying a force to said member for providing said elastic deformation of said member so as to press at least a part of said sidewall part outwards by said member and allowing said sidewall to expand unhindered for providing said one or more projections, and releasing said force.

12. A method according to claim 11, and comprising any of the features and steps according to any of claims 1- 10.

13. A metal container for storage of foodstuff and being provided by a method according to any of claims 1- 12.

14. A metal container according to claim 13, wherein the container comprises two succeeding convex formed parts along its height from the bottom to the top.

15. A metal container according to claim 13 or 14, wherein the container has the same diameter at the bottom and top and a largest diameter at substantially half the height or at substantially 1/4 and 3/4 the height.

16. A metal container according to any of claims 13- 15, wherein the container at the bottom and top has a diameter of between 50 mm and 300 mm, such as 73 mm or 99 mm or 190 mm.

17. A metal container according to any of claims 13- 16, wherein the container is made of tin plate.

18. A metal container according to any of claims 13- 17, wherein the edges of the 5 container are curled to avoid sharp edges.

19. A metal container according to any of claims 13- 18, wherein the material thickness of the container is between 0.15 mm and 0.35 mm.

10 20. A metal container according to any of claims 13-19, and for transportation, storing and sale of cookies being stacked inside the container, and wherein the outer delimitation of the stacked cookies is within the diameter of a bottom part of the container.

15 21. A metal container according to any of claims 13-20, wherein the sidewall before expansion is substantially cylindrical and/or substantially conical.

22. A metal can for storage of foodstuff, the can comprising a container having a substantially circular bottom part and a wall being attached thereto at its lower end, and

20 a lid to be mounted to a top of the wall, the wall having at least one convex form between the bottom and top.

23. An installation for forming a metal container,

25 the installation comprising; at least one forming station for forming said container, and conveyor means for conveying a plurality of containers to and from said forming station,

30 the forming station comprising; at least one deformable member to be positioned inside said container, means for moving said member into and out of said container, 35 - means for expanding said member and allowing a part of a sidewall of the container to expand unhindered so as to form said part into the shape of at least a part of said member when expanded.

24. An installation according to claim 23, wherein the deformable member is adapted to provide one or more convex formed parts in the wall.

25. An installation according to claim 23 or 24, wherein the deformable member is made 5 of a compressible material, such as rubber.

26. An installation according to any of claims 23-25, wherein the deformable member is inflatable.

10 27. An installation according to any of claims 23-26, wherein the member is expanded by pumping it up with liquid or gas.

28. An installation according to any of claims 23-27, wherein the forming station comprises a carrousel comprising a plurality of deformable members.

15 29. An installation according to any of claims 23-28, wherein the means for expanding comprises pneumatic and/or hydraulic and/or mechanical means.

30. An installation according to any of claims 23-29, wherein the means for moving said 20 member comprises a piston attached to the member in its upper end and connected to a roller bearing in its lower end, a guide rail being in engagement with said roller bearing, the guide rail having a curved course in order to move the piston upwards and downwards upon rotation of said carrousel.

25 31. An installation according to any of claims 23-30, wherein the means for moving also is adapted to apply and release a force to/from said member so as to expand and retract the member when moving the piston upwards and downwards, respectively.

32. An installation according to claim 30 or 31, wherein a piston is attached to two

30 deformable members provided on top of each other so as to provide two convex formed parts in the sidewall of a container simultaneously.

33. An installation according to any of claims 23-32, wherein the deformable member is substantially spherical and/or nut-formed when expanded.

35 34. An installation according to any of claims 23-33, wherein the deformable member is substantially cylindrical when not expanded.

35. An installation according to any of claims 23-34, wherein the conveyor means comprises one or more worm conveyors and/or conveyor belts and/or carrousels.

36. An installation according to any of claims 23-35 and adapted to perform the method 5 according to any of claims 1- 12.

37. An installation for producing a metal can with one or more outwardly extending projections in the wall of the can, the can comprising a bottom part and a substantially cylindrical wall attached thereto,

10 the installation comprising; at least one forming station for providing said projections in said wall, and conveyor means for conveying a plurality of cans to and from said forming station, 15 the forming station comprising; at least one elastic deformable member to be positioned inside said cylindrical wall, means for moving said member into and out of said wall 20 - means for applying and releasing a force to/from said member, when the member is positioned inside said wall, for providing said elastic deformation of the member so as to press at least a part of said wall part unhindered outwards for providing said projectιon(s).

25 38. An installation according to claim 37, wherein the elastic deformable member comprises an expandable member according to any of claim 23-36, the member being expanded when applying said force thereto.