Technical field

The present disclosure relates to a method for producing containers in mesh material comprising expanded sheet metal. The disclosure also relates to mesh material containers. The containers have a first and a second set of opposing side panels, a bottom panel, and a rim directed outwards from the upper edges of the side panels.

Background

Such a container is described for instance in EP-1424287-A1 where a container is formed from three mesh pieces and a non-mesh rail is fitted to the upper edges of the container to form a rim or frame. One problem with mesh containers of this kind is how to produce them in an efficient manner to ensure a low-cost manufacturing.

Summary

One object of the present disclosure is therefore to provide a production method with improved efficiency. This object is achieved by means of a method as defined in claim 1. More specifically, in a container of the initially mentioned kind, a web of sheet metal is perforated and expanded along an expansion direction, while leaving a portion of the sheet metal web unstretched. At least one precursor is cut from the web, and a container is folded, including said at least one precursor, wherein the precursor makes up, in one piece, at least a side panel in the first set of side panels and a side panel in the second set of side panels, which are joined by a rim portion comprising said unstretched portion of the web.

This provides a very effective manufacturing of a container, where no special parts need be added to form the rim of the container.

A web of sheet metal may be perforated and expanded along an expansion direction, while leaving leading and a trailing portion of the web unstretched with an intervening stretched portion. The web may be cut across the intervening stretched portion to form a first and a second container precursor, the first container precursor comprising the leading unstretched portion and the second container precursor comprising the trailing unstretched portion. A first container may be formed from the first container precursor, wherein the leading unstretched portion forms the rim of the first container, and a second container is formed from the second container precursor, wherein the trailing unstretched portion forms the rim of the second container.

With this method, an entire container can be formed from one piece of sheet metal, and a separate step of attaching a rail can be eliminated. The result is a significantly improved production efficiency.

In an alternative example, where the web is cut across the intervening stretched portion to form a first and a second container precursors, a container is folded from a leading container precursor and a trailing container precursor, wherein the unstretched portions make up a container rim. In that example the web makes up one whole container only, but can have a much smaller width for a given container size.

Each container may be rectangular having a first and a second set of opposing side panels and a bottom panel. The web parts making up the first set of side panels and the bottom panel of the first container may be aligned with parts making up the second set of panels of the second container, and vice versa. This ensures very little waste of sheet metal when cutting the web.

Each part making up a side panel in the first set may also make up a part of the bottom panel being adjacent to said side panel. This means that no joint is needed between the bottom panel and this side panel, which are formed as one piece and have a very strong connection. The halves of the bottom panel are instead joined with an overlap along the mid of the bottom panel.

To form the rim, each unstretched portions may be folded outwards from the inner of the container and downwards towards the bottom of the container. A hollow channel may be formed inside the rim improving the structural stability thereof.

Each unstretched portion may also comprise the upper part of each side panel, making the rim even more stable.

A bottom panel of the container may be embossed in a pattern to make it more stable.

The present disclosure also considers a mesh material container comprising a first and a second set of opposing side panels, a bottom panel and a rim directed outwards from the upper edges of the side panels. Each of the first set of opposing side panels are formed in one piece with first and second bottom panel portions, respectively. The first and second bottom panel portions are joined with an overlap in the mid portion of the bottom panel of the container. The container bottom panel may be embossed along the overlap to make the connection between the bottom panel halves stronger.

In the mesh container, the rim may be formed in one part with the side panels as an unstretched portion of the sheet metal forming other parts of the mesh. The un stretched portion may reach into the top parts of the side panels. This also makes the rim portion and the side panels stiffer.

The present disclosure generally also considers a container where the rim is formed in one part with the side panels as an unstretched portion of the sheet metal forming other parts of the mesh container. The unstretched portion may continue to a transition line at the upper part of a side panel where the expanded mesh begins.

This makes the upper part of the container with the rim stronger. Openings in rows of openings in the mesh material closest to the unstretched portions may have reduced size as compared to other parts of the mesh material. This reduces the risk of unintentionally deforming the sheet metal at the transition between meshed and unmeshed areas.

The present disclosure further considers a mesh material container with a first and a second set of opposing side panels, a bottom panel and a rim directed outwards from the upper edges of the side panels. The bottom panel is formed with an overlap where two panel portions are joined, for instance by welding. The overlap is provided with an embossing to form, in cross section, an arching shape, for instance forming a half circle arching between the two panel portions. This makes the joint stronger and the bottom panel as a whole stiffer. The edges of the two panel portions may be located within the arching shape.

The present disclosure further considers a mesh material container, comprising expanded sheet metal, the container having a first and a second set of opposing side panels, a bottom panel, and a rim directed outwards from the upper edges of the side panels. At least one side panel in the first set of side panels and one side panel in the second set of side panels being formed in one piece with a rim portion including unstretched portion. The rim portion may comprise a tab with an extension between 15 and 40 mm. Brief description of the drawings

Fig 1 shows a mesh material.

Fig 2 illustrates a partly stretched web of sheet metal.

Fig 3a-3c illustrates how a web as shown in fig 2 is cut to form two precursors for making mesh containers.

Fig 4 illustrates forming a rim of a container.

Fig 5 illustrates a container formed from a precursor as shown in fig 3c.

Fig 6 is a picture of such container with an embossed bottom panel.

Figs 7a and 7b show cross sections through alternative examples of a finished rim portion.

Fig 8 shows an alternative layout for forming two mesh containers in a quadratic format.

Fig 9 is a top view of a quadratic mesh container prior to embossing its bottom panel.

Fig 10 shows the top view of fig 9 after embossing of the bottom panel.

Fig 11 schematically illustrates an overlap between two bottom panel portions at an embossing.

Fig 12 shows an alternative layout for forming a single mesh containers in a quadratic format from a mesh web.

Fig 13 shows an alternative layout for forming two mesh containers in a rectangular format from a mesh web.

Fig 14 is a top view of one of the rectangular mesh containers formed from the web in fig 13.

Figs 15-16 illustrate a first example of assembling of a container.

Figs 17-19 illustrate a second example of assembling of a container.

Fig 20 illustrates a transition between a meshed and an unmeshed area. Detailed description

The present disclosure relates generally to methods for producing containers in mesh materials and containers in mesh materials. By a mesh material 1, an example of which is shown in fig 1 , is meant sheet metal being provided with openings and expanded to widen those openings. Typically, the sheet metal may be pierced with short line-shaped openings and stretched along a stretch direction 3 to form e.g. diamond-shaped openings 5 in the sheet metal, as illustrated in fig 1.

EP-1424287-A1 describes a method for producing a container for a drawer system. The container comprises upper rail and a basket portion coupled thereto. The basket portion comprises panels of mesh material. In one illustrated example, the basket is formed by three separate mesh pieces, one typically forming the bottom and two opposing side walls, while the other two form the remaining two side walls in a rectangular basket. Seams are formed between the separate parts and a rail may be welded at the rim of the container.

In the present disclosure a more efficient method of producing a mesh container is described. This is accomplished for instance with less waste of material, fewer parts and fewer production steps, each providing an advantage over prior art methods.

In the present disclosure, rather than separately forming pieces making up different panels of a container by cutting up a perforated, stretched web of sheet metal, welding those pieces together and attaching a separate rail at the rim of the container, the container is formed almost as a whole already from a single web of sheet metal by preparing one or more mesh metal container precursors.

Generally, thus, a web of sheet metal is perforated and expanded along an expansion direction, while leaving a portion of the sheet metal web unstretched. At least one container precursor is cut from the web, and a container is folded, including said at least one precursor, wherein the precursor makes up, in one piece, at least a side panel in the first set of side panels and a side panel in the second set of side panels, which are joined by a rim portion comprising said unstretched portion of the web. Thereby, a very effective manufacturing of a container is provided, where no special parts need be added to form the rim of the container.

Fig 2 schematically illustrates a partly stretched web 7 of sheet metal. This web may be formed from the entire width of a roll of sheet metal, typically steel. The web may typically be a few meters wide, e.g. about 1900mm. The web may be produced from the roll in the direction illustrated by the arrow of fig 2, and may be perforated and expanded by a processing machine along an expansion direction which may coincides with the indicated direction The processing machine may simultaneously cut and expand the material with sets of knives that first provide a cut transversely to the feed direction of the roll and then widens this cut into an almost rhomboid shape by driving the knife, having a widening cross section, further through the cut. The web 7 of sheet metal is thus cut across and expanded along an expansion direction 3. However, a leading 11 and a trailing 13 portion of the web 7, is left uncut/- stretched with an intervening cut and stretched portion 9. After the trailing web portion 13 the web 7 is separated from the remainder of the roll.

The web 7 formed as illustrated in fig 2 is then cut to form two precursors 18, 20 for making mesh containers as shown in figs 3a-3c. This is done by cutting the web 7 across the stretched portion 9. Further, some parts of the stretched portion 9 are removed to form the shapes illustrated in fig 3b. In fig 3c, the leading web part (bottom) and the trailing web part (top) each form a container precursor 18, 20.

Each web part includes parts 21, 23 to form side panels in two opposing pairs, parts 25 to form a bottom panel, and parts 19 to form a rim portion. In the illustrated case, the container will have panels forming long and short side walls, although a quadratic layout for sure is conceivable. A complete or almost complete container can now be formed from the first container precursor 18, where the leading unstretched portion forms the rim of the first container, adjacent parts 21 , 23 making up side panels are joined with a small overlap, e.g. by welding, and parts 25 making up the bottom panels are mutually joined with a small overlap, and also joined laterally in the same way, i.e. with small overlaps, with the bottom edges of the panels 23 which they are not extending from.

A second container may be folded in the same way from the second container precursor 20 wherein the trailing unstretched portion 19 forms the rim of the second container.

As can be seen e.g. in fig 3c, parts in the web making up the first set of side panels 21 and the bottom panel 25 of the first container precursor 18 are aligned with parts making up the second set of panels 23 of the second container 20, and vice versa. This means that alternating deeper portions, making up a side panel 21 and a half bottom panel 25, of one container precursor are aligned with more shallow portions, making up only a side panel 23, of another. This results that only a small fraction of the expanded web portion 7 need be cut away, as best seen in fig 3b. This means that very little material waste need be recycled. Having one half of the bottom portion 25 in one piece with a side panel 21 also reduces waste and makes the finished container stronger.

Fig 4 illustrates forming a rim or frame of a container. As there is left an unstretched portion 19 (of. fig 3c) adjoining the stretched portions forming side panels 21 , 23, that portion can be used to form the rim of the container. This can be done by folding the unstretched portion 19 outwards from the inner of the container. In principle, simply forming a single layer flange in that way would be possible. However, as the sheet metal may be rather thin, e.g. 0,7 mm, different measures for strengthening the rim and thereby the container as a whole may be considered, either individually or in combination.

The outer part of the unstretched portion 19 may be folded downwards towards the bottom of the container. Such a bend provides more stiffness to the rim. Further the edge of the unstretched portion 19 may be folded or rolled inwards towards the outer face of the associated side panel as shown in fig 4. This may form a double sheet layer or even better a hollow channel at the rim 27 that provides additional structural rigidity to the rim portion. Further, as the edge of the unstretched portion may in principle comprise burrs etc, bending the edge inwards gives the outer periphery of the rim becomes more pleasant to hold when carrying the container.

As also illustrated in fig 4, it is possible to let the unstretched portion make up also the top part of the side panel. This means that the outwards projecting rim portion is folded a few centimetres into the unstretched portion. This also makes the rim portion stronger.

Fig 5 illustrates a container 29 formed from a precursor as shown in fig 3c. This container can be made in one piece, comprising joints/overlaps 31 only at the middle of the bottom panel 25, between the side panels 21 , 23 and between the joint bottom panel 25 and the short-side side panels 23. The rim portion also needs a joint 31 , but only at one location. The overall construction becomes very strong despite being made in a thin material and in one piece. As shown in the picture of fig 6, the bottom of the container may be embossed with a pattern, in the illustrated case a square ridge pattern. This gives the bottom panel some stability such that it becomes less prone to bulge in a direction perpendicular to its plane and is therefore perceived as less flimsy. An embossed ridge along the overlap between the two bottom panel halves makes the connection between those halves somewhat stronger as will be shown.

While fig 4 illustrated the rim portion during forming thereof, fig 7a shows a cross section through a finished rim portion 27. As the rim portion 27 is in one piece with the side panel 21 , there is no need for a specific operation attaching the rim portion 27 to the remainder of the container. The rim portion 27 could be shaped before folding and joining the panels for the container, but it may be preferred to form the rim portion 27 as a subsequent step instead. In any case, the rim portion 27 is made by bending unstretched portion outwards, out of the plane of the side panel 21 , at a bend 35, typically a little less than 90 degrees. The outward extending portion is then bent downwards and inwards, forming in cross section a first 37, top and outwards extending, leg and a second 39, bottom and inwards extending, leg joined by an outer bend 38. While this outer bend 38’ could be sharp, forming a flat double layer from the first and second legs 37, 39 as indicated in fig 7b, it is preferred to form the outer bend 38 with a radius. The second leg 39 may then be bent almost until its edge 40 touches the first leg 37. This provides the aforementioned channel 33 with a drop-shaped cross section and has several advantages. The rim portion 27 thereby becomes stiffer, and the edge 40 of the second leg 39 becomes hidden to some extent which limits the need for removing burrs, etc. on the edge 40. As already indicated the unstretched portion may reach down on the side panel to a transition line 41 to provide additional stability to the rim portion 27. Thus, above this line, the panel is unstretched 19, but below it is perforated. Preferably, the first few rows of openings 5 in the mesh, closest to the transition line 41 have a reduced size, increasing gradually for e.g. three rows from the transition line 41. This reduces the risk of the sheet metal being deformed by the transition from non-mesh to mesh. An example is illustrated in fig 20. In order to achieve the reduced openings, the tool cutting and expanding the sheet metal makes shallower strikes when forming the first few rows of openings. Fig 8 shows an alternative layout for forming two mesh containers in a rectangular format. As in figs 3a-3c, first and second precursors 18, 20 are formed from leading and trailing portions of a sheet metal web where an unstretched portion 19 is kept at the leading edge of the first precursor and in the trailing edge of the second precursor, respectively. In this example, each side panel 21, 23, is formed in one piece with a portion 25, 26 that will form part of the bottom panel. Thus, from each side panel 21 in an opposing pair of panels a comparatively short and wide tongue

25 extends. From the panels 23 in the other pair, a longer and more narrow tongue

26 extends. When a precursor 18, 20 is folded into a container, the ends of the longer and narrower tongues 26 will meet and form an overlap in the middle of the container, while the shorter and wider tongues 25 cover the areas at the lateral sides of the longer and narrower tongues 26 and form overlaps therewith that are welded to form the container bottom.

This is illustrated in fig 9 where the overlaps 43 form an FI-shaped configuration. In addition to this, welded overlaps are needed in between the side panels 21 , 23 and overlaps 45 between the lateral sides of the shorter and wider tongues 25 and the corresponding side panels 23. This means that overlaps and corresponding welds are moved away from the transition between side panel and bottom panel to a large extent. Along the bottom panel periphery where it meets the side panels, overlaps 45 are only needed at four shorter sections, which are located close to the corner where the strength requirements are not as high. Along a greater part of the periphery 47 the side panels 21 , 23 and the adjoining portions of the bottom panels 26, 26 are joint-free, made in one piece, and thus there is no risk of a weld or the like being broken. The overlaps in the bottom panel may be embossed to provide increased strength, keep burrs and the like away, eliminate the bottom panel bulging, and provide an aesthetically interesting appearance. This will be described with reference to figs 10 and 11.

Fig 10 shows the top view of fig 9 after embossing of the bottom panel. Indicated in the figure is the location of a rectangular embossing pattern 49. This pattern may give the impression of a legacy-type wire basket. The pattern also makes the bottom panel as a whole stiffer, less likely to bulge. This is schematically illustrated with a cross section through a joint between two bottom panel portions 25, 26 in fig 11. The joint may be formed by providing an overlap between the two panel portions, and e.g. welding or soldering to join the portions at the overlap, as is known per se. In addition to this, the embossing 49 is provided that in cross section provides e.g. a half-circle shape arching between the two panel portions 25, 26. This embossing 49 makes the joint between the panel portions 25, 26 stronger, and further the bottom panel as a whole becomes less flimsy, as the panel is not prone to bend at all about an axis which is parallel with the cross section of fig 11 and the bottom panel as a whole. Additionally, the embossing to some extent folds away the panel portion edges that may contain burrs, etc. and on which fabrics and the like may otherwise become entangled. The edges 28, 30 of the two panel portions 25, 26 may thus be located within the arching shape formed by the embossing to provide this effect. The embossing can be made protruding upwards or downwards from the bottom panel main plane, and need not form a half circle, as other cross section shapes are conceivable.

Fig 12 shows an alternative layout for forming a single mesh container in a rectangular format from a mesh web. This alternative may be preferred for instance to form large containers, where a container precursor having all side panels connected to a single unstretched area requires a perforating/expanding machine capable of processing a very wide web. In the arrangement in fig 12 the whole width, e.g. about 950 mm, of the web is used for one panel each in a first and a second pair of opposing panels. The leading precursor 51 thus forms two side panels 21, 23, and the trailing 53 the two others. This allows the container to be produced in a less expensive production line at the cost of adding another joint in the unstretched portion forming the rim, i.e. two joints instead of one. Those precursors 51 , 53 may still be used to form a container as in figs 9 and 10.

The layout of fig 12, where the web makes up one single container has another advantage. When folding a container from the precursors in fig 12, the bottom portions 25 that will be joined in the bottom panel are stretched in the same way at the location where they are joined. With reference to fig 8, that layout in contrast requires that one bottom portion 25 is turned 180 degrees in relation to the other from the orientation in which the web was stretched before the bottom portions 25 can be joined. With reference to fig 1 , that mesh structure will have a general visual appearance that is very much different depending on the viewing angle. Therefore, turning the bottom portion, as required with the embodiment of fig 8, may make one half of the bottom portion look lighter than the other, while the embodiment in fig 12 may give a visually more or less seamless transition from one bottom portion 25 to the other.

Illustrated in the enlarged portion A of fig 12 is a tab 22, which is cut to project in the long direction of the unstretched area. This tab facilitates making the joint of a rim portion which thanks to the tab need not be located directly at a corner of the container where it would be more exposed. Instead, the joint can extend into a rim portion side, providing for a stronger joint. The cut can be made such that the tab projects about 25 mm from the remainder of the rest of the precursor, or typically in a range between 15 and 40 mm.

The layout where each side panel in a precursor adjoins with a part of the bottom panel is not restricted to the quadratic format. For instance, fig 13 shows a layout for forming two mesh containers in a rectangular format from a mesh web in a very similar way as with the layout of fig 8. Fig 14 is a top view of one such rectangular mesh container formed from the web in fig 13. This layout as well could have the half width, where the leading precursor forms one part of a container and the trailing precursor another, similar to in fig 12.

Figs 15-16 illustrate a first example of assembling of a container, more specifically a rectangular container where two panels are formed by a leading precursor 51 from the web, and two panels from a trailing precursor 53 from the web, similarly as in fig 12. Each precursor 51 , 53 is pre-formed by folding as illustrated in fig 15, folding out the parts forming the bottom panels from the side panels, and folding the adjoining side panels to form a corner therebetween. Wide tabs may be provided to facilitate this. Then, the two such precursors 51 , 53 are assembled and welded together to form the finished container, As can be seen in fig 16, the rim portion is not formed prior to this stage. Instead it is possible to form this portion by rolling the unstretched edge of the assembled container.

Figs 17-19 illustrate an alternative, second example of assembling of a container. This example uses a precursor as shown in fig 3c where one precursor 18 formed from the entire width of the web is enough to form all panels of the container. In this case a rim 27 is formed as a first step, before folding the panels and assembling the container. Either forming the rim 27 before or after assembling the panels to a container is possible for all variations of precursors. The present disclosure is not limited to the above examples and may be varied and altered in different ways within the scope of the appended claims.