FIELD OF THE INVENTION

This invention relates to a container, especially a food container, having an interlocking cover arrangement, the container having a tray member including a plane bottom wall and four tray member side walls upstanding from the latter to form a box-like structure open at the top, the tray member side walls each includes an outer flange ele¬ ment, the container also has a cover member including a plane top wall and four cover member side walls depending from said top wall to form a box-like structure open at the bottom, each of two opposite side walls of said cover member side walls having at least one biassed locking ton¬ gue presenting an upwardly facing abutment for engagement with a corresponding downwardly facing abutment on said tray member.

BACKGROUND ART

Such containers including interlocking covers are known from US-B-4, 114,798. The known container does, however, not provide a sufficiently strong locking function between the tray and the cover members.

SUMMARY OF THE INVENTION

The object of the present invention is, therefore, to pro- vide a container of the aforementioned kind, which provi¬ des a stronger and safer interlocking between the tray and cover members. This object will be achieved by a con¬ tainer according to the invention and having the characte¬ ristics set forth in Claim 1.

According to the invention the outer flange elements con¬ sist of brims projecting outwardly from the periphery of

the tray member in a direction substantially parallel to the plane of the bottom wall of the tray member, said ♦ brims each having a bottom surface forming said downwardly facing abutment, and said brims each having a top surface forming an abutment surface for engagement with said top wall of the cover member, an opposed pair of the brims ha¬ ving apertures for mating engagement with each of said locking tongues by snap-action.

It has proved that the interlocking between the tray and cover members becomes so strong that it is possible to safely lift a container also when it is filled with food by lifting the container in its cover member.

Further developments of the invention are set forh in the subclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail by refe¬ rence to the accompanying drawings, which illustrate a preferred embodiment of the invention.

Fig. 1 is a perspective view of a tray member according to the invention.

Figs. 2 - 5 illustrate four seguential stages for the ma¬ nufacture of a tray member according to the invention.

Figs. 6 - 7 illustrate in sequence two operational stages in interlocking a tray member and a cover member according to the invention.

PREFERRED EMBODIMENT

Fig. 1 shows a rectangular tray member 1 of a plane, stiff material, for instance a paperboard material. The tray mem-

ber has a plane bottom wall la and four side walls lb-e up¬ standing from the bottom wall la to form a box-like struc¬ ture open at the top. Each tray member side wall lb-e has an outer flange in the form of a brim 2, 3, 4, and 5, re- spectively, projecting outwardly from the periphery of the tray member in a direction substantially parallel to the plane of the bottom wall la of the tray member. The tray member may be either right-angled or conical in order to enable a piling of several tray members into one another. The tray member may also be foldable, for instance of the type described in Swedish patent specification Number 8405157-2.

Each of the two opposed brim portions 2 and 4, see Fig. 1, has two through, oblique apertures 6, 7 and 8, 9, respec¬ tively, which improve the interlocking function, as will be explained below.

Fig. 2 shows a cut out plane blank of a plastic treated paperboard or the like, which, after folding and glueing, will form the cover member illustrated in Figs. 3 - 5.

The cover member has, see Fig. 2, a plane top wall 10 and four rectangular cover member side walls 11 - 14 foldable downwards at approximately right angles via fold lines

15 - 18 such that the four side walls 11 - 14 will depend from the top wall 10 to form a box-like structure open at the bottom. In the embodiment shown, the side walls 11 - 14 have been cut out in a manner such that the box-like structure will converge conically downwardly. The two lon¬ ger side walls 12 and 14 have, at their ends, an exten¬ sion portion 12a, 12b and 14a, 14b, respectively, which can, via fold lines 19 - 22, be folded inwardly at appro¬ ximately right angles to the longer side walls 12 and 14, respectively, and be fastened, for instance by adhesive

23 - 26, to an adjacent short side wall 11 and 13, respec¬ tively, see Fig. 3.

Each end of the short side walls 11 and 13 has a fold li¬ ne 27 - 30, respectively, extending in about 45 degrees from a respective one of the corners of the top wall 10. These fold lines 27 - 30 enable an infolding of the short side walls 11 and 13 towards the top wall 10, see Fig. 4, to permit the cover member to be collapsed into a flatte¬ ned condition, see Fig. 5, which condition the cover mem¬ ber will have during transport prior to packing of the tray member.

The adhesive 23 - 26 has been applied only to a triangular area, see Fig. 2, at the end of each short side wall 11 and 13, which area is located outside the respective fold line 27 - 30, thus causing only a corresponding triangular area of the extension portions 12a-b, 14a-b, to be glued to an associated one of short side walls 11 and 13. Thus, the outermost area of the extension portions 12a-b and 14a-b, respectively, will remain free from the adhesive and will not be glued to its associated short side wall 11 and 13, respectively. This will accomplish the special ef¬ fect that the non-glued areas of the extension portions 12a-b and 14a-b, respectively, will move relative to its associate short side wall, when this is being infolded to¬ wards the top wall 10, as is seen in Fig. 4.

When raising the cover member from its flattened conditi¬ on, shown in Fig. 5, to an erected condition, the inherent springiness of the paperboard material will endeavour to counteract any raising of the cover member, i.e. it will endeavour to maintain the short side walls 11 and 13 in¬ folded towards the top wall 10. Thus, the cover member will endeavour, in its erected condition, to take the con¬ dition shown in Fig. 4, where the non-glued areas of the extension portions 12a-b and 14a-b, respectively, will point obliquely inwards towards the cover member. The non- glued areas of the extension portions 12a-b and 14a-b, respectively, can, thereby, be used as a kind of locking

tongues, which can be said to be indirectly biassed by said inherent springiness of the paperboard material of the short side walls of the tray member. The function of these locking tongues will be apparent from the descripti- on below by reference to Figs. 6 and 7.

Fig. 6 is a perspective view, as seen obliquely from be¬ neath, of a cover member according to the invention, whe¬ reas Fig. 7 is a perspective view, as seen obliquely from beneath, o~ H tray member 1 with a cover member telescoped over the tray member.

When the cover member is to be locked against the tray member 1, its short side walls 11 and 13 are first pulled outwardly (in the directions shown by arrows 31 and 32 in Fig. 6) against the action of the inherent springiness of the paperboard material. The cover member can now be tele¬ scoped down over the tray member 1 until the top wall 10 will abut against the top surface of the brims 2 - 5 of the tray member. In this condition, the non-glued areas of the extension portions 12a-b and 14a-b, respectively, will move in under the brims 2 - 5 and engage the bottom surfa¬ ce of the brims by snap-action, see Fig. 7, and will thus interlock the cover member to the tray member. If the non- glued areas of the :tension portions 12a-b and 14a-b, re¬ spectively, are eac_χ provided with a hook or heel 33 - 36, see Figs. 2 and 4, these hooks or heels can snap into a respective one of the oblique apertures 6 - 9 provided in the brims 2 - 5, and will thus improve the interlocking between the tray and cover members.

The effective locking depth provided by the apertures 6 - 9 is in fact greater than the thickness of the brims 2 - 5. Namely, in practice, the brims 2 - 5 will not be oriented exactly in parallel with the top wall 10 of the cover member, but will incline a few degrees, such that the locking tongues, when moving through the apertures,

will move a certain distance past the apertures, which will cause a still stronger interlocking between the tray and cover members.

The length of the extension portions 12a-b and 14a-b and the configuration, location and angle of the apertures 6 - 9 is dimensioned such that the non-glued areas of the extension portions (i.e. the "locking tongues") or their heels or hooks 33 - 36, if such are present, will obtain the same direction and location as the apertures in order to ensure that the locking tongues will get an optimal en¬ gagement with its associated aperture.