GB2237796A - Blanks for packaging - Google Patents

Abstract

A blank for forming a carton comprises a central rectangular panel (1), end panels (2, 3), side panels (6, 7) and a corner structure (10 to 13) joining adjacent end and side walls at each corner of the central panel. Each corner structure comprises a first flap (14) attached to an end of the respective end wall along a first fold line (15) and a second flap (16) attached to an end of the respective side wall along a second fold line (17), the first and second fold lines including an obtuse angle and the first and second flaps being attached one to the other along a third fold line (19). <IMAGE>

Description

CARTON BLANK AND PACKAGE This invention relates to a carton blank, to a method of forming a carton from the blank, to the carton so formed and to a packaging method and package based thereon.

Goods such as partially prepared food for subsequent cooking or reheating are now commonly sold in containers comprising a tray, with a sealed lid closing an open top of the tray. The tray is commonly inserted into a sleeve for presentation at point of sale, the sleeve surrounding the tray in a wrap-around fashion and having open ends. The tray is prevented from sliding out of the sleeve by cut and folded sections of the sleeve, which are pushed inwardly from the remainder of the sleeve at the ends thereof in order to engage opposite ends of the tray. Although this is a reasonably effective packaging system, it does have certain disadvantages, as pointed out in our co-pending UK patent application number 8915321.7.Thus, the locking effect leaves something to be desired, and it is also simple to remove the tray either wholly or partially from the sleeve, in order that the tray may be tampered with.

Our aforesaid application describes a carton which enables more secure locking, and makes tampering with the tray and its contents very much more evident. The present invention is directed to the same ends, and provides a construction that will in some circumstances be more advantageous than our earlier constructions. The invention provides packaging that is suitable not only for partially prepared food in sealed trays, but also to any type of goods in many different types of container.

According to a first aspect of the invention a flat blank for forming a carton comprises a central rectangular panel, end panels joined by respective first junction lines to opposite ends of the blank, side panels joined by respective second junction lines to opposite sides of the blank, and a corner structure joining adjacent end and side walls at each corner of the central panel, in which each corner structure comprises a first flap attached to an end of the respective end wall along a first fold line and a second flap attached one to an end of the respective side wall along a second fold line, the first and second fold lines including an obtuse angle, and the first and second flap being attached one to the other along a third fold line intersecting the angle between the first and second fold lines, the point of intersection being at or adjacent to the point of intersection between the respective first and second junction lines.

According to a second aspect of the invention a method of forming the aforesaid blank into a carton comprises folding the end and side panels out of the plane of the central panel, and folding each corner structure about the first, second and third fold lines so that the third fold line moves inwardly over the central panel and surfaces of the first and second flaps move into a contiguous relationship, and securing the contiguous surfaces together by adhesive means so as to hold the carton assembled with the side panels constituting side walls each projecting from a base formed by the central panel the side walls converging inwardly over the base and each lying at an acute angle to the plane of the base. The method may if desired be carried out in stages at different stations of suitable equipment.

According to a third aspect of the invention a method of forming a package comprises locating the central rectangular panel of the aforesaid blank adjacent to and substantially coterminous with a top of a container, and completing formation of a carton around the container in the aforesaid manner so that the converging side walls retain the container in position within the carton.

The invention further extends to cartons and to packages formed by the aforesaid methods.

The method of forming the blank into the carton is particularly easy to automate, as the three fold lines of each corner structure constrain that corner structure and the end walls and side walls to move automatically into the required positions relative to the central rectangular panel. It is a straightforward operation to apply adhesive between the contiguous surfaces of the first and second flaps as these move to their position of engagement, and to hold the flaps in engagement until the adhesive hardens to hold the carton in its assembled position. This can readily be carried out even with a container positioned in the required relationship to the blank, and when the carton is so assembled the container is firmly held in position within the carton by the converging side walls.These define between them an opening having a width less than the maximum width of the container, so that the container cannot be removed from the carton without obvious signs of damage. The minimum angle of convergence of the side walls to hold any particular container can readily be calculated, and will generally depend on the depth of the container and on the angle of any taper with which the walls of the container may be formed.

In one embodiment of the invention the first fold line makes an obtuse angle with the respective second junction line, and the second fold line forms a straight extension of the respective first junction line. When a blank of this type is folded into a carton then only the side walls of the carton will converge inwardly over the base of the carton.

In a second embodiment, the first fold line makes an obtuse angle with the respective second junction line, and the second fold line forms an obtuse angle with the respective first junction line, and lies between the respective first and second junction lines. In this embodiment the side walls will converge inwardly over the base, and the end walls will similarly converge inwardly over the base.

The terms "end panels", "side panels", "end walls" and "side walls" are used for convenience: they do not imply any length relationship between the panels or walls, and the end panels or walls may be shorter than, equal in length to, or longer than the side panels or walls.

The angle of convergence of the side walls and/or the end walls will depend on the angle between the first and second fold lines, and the angles that those fold lines make with the respective first and second junction lines.

It is preferred that the third fold line bisects the angle between the first and second fold lines, although this is not essential. When it does bisect the angle then the first flap may be symmetrical with the second flap along a line of symmetry formed by the third fold line.

Again, however, this is not essential, and in certain embodiments of the invention it may be preferred if the second flap has a section projecting beyond the first flap.

The free edge of at least one of the side or end panels may have a flap joined thereto along a fold line extending the full length of that free edge and parallel to the junction line joining that panel to the base.

When a carton is formed from a blank having panels without such flaps then it may be found that one or more of the walls will bow out of the ideal planar arrangement.

Provision of a flap along the edge of the panel, which flap is folded over and glued to the remainder of the panel during assembly of the blank will prevent such bowing, and will also reinforce the panel.

If desired, any such flap joined to a panel may be made of a width measured transversely of the panel that is slightly less that the width of the panel. If that flap is folded inwardly of the panel during assembly of the carton it may then engage a rim that can be provided on the container, in order to enhance the locking effect of the container within the carton. In this context, reference should be made to our aforesaid co-pending application.

In order that the invention may be better understood specific embodiments of blanks and cartons in accordance therewith will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Fig 1 shows a first embodiment of blank in accordance with the invention; Fig 2 shows a partly folded corner structure of the blank of Fig 1; Fig 3 is a plan view of a carton assembled from the blank of Fig 1; Fig 4 is a partial section on the line IV-IV of Fig 3 showing a fully folded corner structure; Fig 5 is a section on the line V-V of Fig 3 showing a package comprising the carton of Fig 3 and an associated container; and Figs 6 and 7 each show a further embodiment of a blank according to the invention.

Referring to Fig 1 this shows a flat blank of cardboard, box board or the like from which a first form of carton may be assembled. The blank has a central rectangular panel 1, two end panels 2, 3 joined by respective first junction lines 4, 5 to opposite ends of the blank, and two side panels 6, 7 joined by respective second junction lines 8, 9 to opposite sides of the blank.

At each corner of the blank there is a corner structure 10 to 13, and as these are all identical only corner structure 10 will be descried in detail.

Corner structure 10 joins adjacent end and side panels 2 and 6, and comprises a first flap 14 attached to an end of the end panel 2 along a first fold line 15, and a second flap 16 attached to an end of the side panel 6 along a second fold line 17. The flaps 14 and 16 are attached one to the other along a third fold line 18.

The first fold line 15 make an obtuse angle with the junction line 8 while the second fold line 17 forms a straight extension of the junction line 4. The fold lines 15 and 17 include between them an obtuse angle, which is bisected by the third fold line 18. The fold lines 15, 17 and 18 intersect at or adjacent to the point of intersection between the junction lines 4 and 8. The flaps 14 and 16 are symmetrical along a line of symmetry formed by the third fold line 18.

The blank of Fig 1 is formed into a carton by folding the end and side panels 2, 3, 6, 7 upwardly out of the plane of paper as shown in Fig 1, at the same time folding part 19 of each corner structure upwardly and inwardly over the rectangular panel. The corner structure thus folds about all three fold lines 15, 17 and 18 so that the lower surfaces as seen in Fig 1 of the flaps 14 and 16, those surfaces being shown as 20, 21, in Fig 2. are brought together and moved into a contiguous relationship. Before they reach that position adhesive is applied to those facing surfaces, and when the fold is complete the flaps are held in contact until the adhesive sets.

In the finished container the flaps forming the corner section may be folded back to lie adjacent to the associated side wall, or may project diagonally inwardly over the base of the container that is formed by the central rectangular panel. The former arrangement is shown in Fig 3 and 4, and it will be seen that the basic configuration of the carton is that of a base with four upstanding walls, two opposite end walls which are perpendicular to the plane of the base, and two opposite side walls 25, 26 which converge inwardly over the base and which each lie at an acute angle to the plane of the base.

The angle between each side wall and the base is dictated by the value of the obtuse angle between the fold line 15 and the associated junction line 8.

Formation of the blank into a carton will generally be carried out in two stages. In the first stage, the blank is passed through equipment for breaking the corner and side wall creases and for partially erecting the blank to a form in which each fold line 18 lies perpendicular to the plane of the central panel 1. The partially erected blank, and a container to be covered by the carton, are then offered one to the other, with a top of the container presented to the central panel 1 and substantially coterminous therewith.

Folding of the blank, and adhering the corner structures thereof is then completed. Fig 5 shows a package formed in this way; the container 27 has a base 28 a top 29 and tapering sides 30, and the side walls of the carton are preferably formed so that their convergence is steeper than the taper of the container walls. As will be apparent from Fig 5 the dimension x between the opposite edges of the side walls is less that the maximum dimension y across the top of the container, with the result that the container is firmly locked within the carton.

The container will generally have been closed, the top 29 being formed by a lid sealed along the full length of the four walls of the container.

Referring now to Fig 6 this shows a slightly modified form of the blank of Fig 1. and corresponding parts are given the same reference numeral with the suffix a. The blank is modified from that of Fig 1 simply by the addition of a flap 31 joined to the side panel 6a along a fold line 32, and by a corresponding flap 33 joined to the side panel 7a along a fold line 34. Prior to, or as part of, the assembly of the carton the flap 31 is folded to overlie the side panel 6a and is adhered thereto, and the flap 33 is similarly folded to lie over side panel 7a and is again adhered thereto. The presence of these flaps means that any tendency of the side walls of the finished carton to bow is counteracted, so improving the appearance of the carton and also strengthening the side walls thereof.It will be appreciated that, if required, flaps similar to flaps 31 and 33 may be formed on the end walls 2a and 3a instead of the side walls 6a and 7a, or may be provided on both side walls and both end walls. Indeed, if there is a tendency for only one wall to bow then it is possible to provide only that single wall with an associated flap.

Fig 7 again shows a further embodiment of blank similar to that if Fig 1. and similar parts are shown by the same reference numerals as used in Fig 1, with the suffix b. In this arrangement each second flap 16b of each corner structure is provided with an extension 41 that extends beyond the first flap 14b and that is separated from that flap by a cut 42. The cut ensures that the extension does not interfere with the folding action of the corner structure, but the extension may improve engagement of the flap with the container in the assembled package.

This is particularly so if the container has an outwardly projecting rim or flange around the top thereof, in which case the extension can lock under that rim.

In the embodiments shown in the drawings, it is only the first fold lines 15 which make an obtuse angle with their associated junction lines. This results in a carton in which the side walls only converge over the base. It will be appreciated that the first fold lines 17 may also be arranged at an obtuse angle to the respective junction lines 4 or 5, and when the blank is so modified then in the finished carton the side walls will converge over the base, and the end walls will also converge over the base, so further improving the retention of a container within the carton.

Claims (11)

1. A flat blank for forming a carton, the blank comprising a central rectangular panel, end panels joined by respective first junction lines to opposite ends of the blank, side panels joined by respective second junction lines to opposite sides of the blank, and a corner structure joining adjacent end and side walls at each corner of the central panel, in which each corner structure comprises a first flap attached to an end of the respective end wall along a first fold line and a second flap attached to an end of the respective side wall along a second fold line, the first and second fold lines including an obtuse angle, and the first and second flaps being attached one to the other along a third fold line intersecting the angle between the first and second fold lines, the point of intersection being at or adjacent to the point of intersection between the respective first and second junction lines.

2. A blank according to claim 1 in which the first fold line makes an obtuse angle with the respective second junction line, and the second fold line forms a straight extension of the respective first junction line.

3. A blank according to claim 1 in which the first fold line makes an obtuse angle with the respective second junction line, and the second fold line forms an obtuse angle with the respective first junction line, and lies between the respective first and second junction lines.

4. A blank according to any one of the preceding claims in which the third fold line bisects the angle between the first and second fold lines.

5. A blank according to claim 4 in which the first flap is symmetrical with the second flap along a line of symmetry formed by the third fold line.

6. A blank according to claim 4 in which the second flap has a section projecting beyond the first flap.

7. A flat blank for forming a carton, substantially as described herein with reference to any one of Figures 1, 6 and 7 of the accompanying drawings.

8. A method of forming the blank of claim 1 into a carton comprising folding the end and side panels out of the plane of the central panel, and folding each corner structure about the first, second and third fold lines so that the third fold line moves inwardly over the central panel and surfaces of the first and second flaps move into a contiguous relationship, and securing the contiguous surfaces together by adhesive means so as to hold the carton assembled with the side panels constituting side walls each projecting from a base formed by the central panel, the side walls converging inwardly over the base and each lying at an acute angle to the plane of the base.

9. A carto,n formed by the method of claim 8.

10. A method of forming a package comprising locating the central rectangular panel of a blank according to any one of claims 1 to 7 adjacent to and substantially coterminous with a top of a container. and completing formation of a carton around the container in accordance with the method of claim 8 so that the converging side walls retain the container in position within the carton.

11. A package formed by the method of claim 10.