GB2317877A - Stackable trays - Google Patents

Abstract

A tray made of e.g. corrugated board has stacking lugs (10) provided as integral upward extensions of at least some of its side walls, and corresponding recesses (12) in the base to receive the said stacking lugs of a similar tray immediately beneath it in a stack. The stacking lugs are formed on the innermost sheet of a wall which is made up of at least two thicknesses of board.

Description

This invention relates to trays and like containers made of cardboard, corrugated board or similar lightweight foldable sheet material, for storing and transporting all manner of articles but particularly edible produce such as lettuces, tomatoes and other vegetables.

Such trays must be stackable one upon another in use. It is therefore customary to make the side walls, and particularly the corner regions, of such trays sufficiently strong in vertical compression to enable a number of filled trays to be stacked in a pile without damaging the lower ones. It is also conventional to provide stacking lugs as integral upward extensions of the side walls, which lugs engage in corresponding slots or recesses in the bottom of the next tray up in a stack, with the object of stopping the trays from moving horizontally relative to each other. These stacking lugs do not always work well, however. In particular, they do not always prevent one or more of the sides of an upper tray, especially if it is relatively heavily loaded, from falling down inside the tray below it, so as to rest on the contents of the lower tray and probably damage them.

According to the present invention there is provided a tray or like container made of cardboard, corrugated board or similar lightweight foldable sheet material, having a base and upstanding side walls, stacking lugs being provided as integral upward extensions of at least some of said side walls, and corresponding slots or recesses being provided in the base of the tray to receive the said stacking lugs of a similar tray immediately beneath it in a stack, wherein each of the said stacking lugs is formed on the innermost sheet of a wall which is made up of at least two thicknesses of sheet material.

With such an arrangement, the tendency for part of an upper tray to fall down inside a lower one is substantially reduced as compared with previous arrangements in which the walls provided with stacking lugs were only one sheet thick, or were of two thicknesses with the stacking lugs on the outer thickness. In broad terms this is because, considering the case of two properly stacked trays according to the invention, a side of the upper one has to move further inwardly before it clears the relevant stacking lug or lugs of the lower one, before it can fall down inside the latter, as compared with such previous arrangements.

However, the invention provides for more positive prevention of such inward movement when, as in a preferred embodiment, each of said slots or recesses has sheet material extending along the outer side thereof to laterally engage the outside of a stacking lug of a lower tray when received in said slot or recess.

In a preferred form of the invention the said at least two thicknesses of sheet material comprise an inner wall panel on which the said stacking lug is formed and an outer wall panel hingedly connected to said inner wall panel about two laterally spaced hinge lines at their top edges, the stacking tab being released from the area of board between the said hinge lines. The said outer wall panel may be hingedly connected to a base panel of the tray, as in a conventional double thickness wall.

The greater the total thickness of the wall that carries a said stacking lug, the more effective is the lug in achieving its intended function, because the further the side of an upper tray has to move inwardly before clearing the lug and falling down inside the lower tray. Preferably, therefore, the said wall is made up at least partly of three thicknesses of sheet material in the region of said stacking lug. Then, when the said at least two thicknesses of sheet material comprise inner and outer wall panels as aforesaid, the third thickness of sheet material may be provided by a flap hingedly connected to another adjacent wall and extending between said inner and outer wall panels, or by a flap hingedly connected to the end of the outer wall panel and folded in between the two panels.

The scope of the invention also extends to blanks for making containers as set forth above.

Two embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a plan view of a blank for making a tray according to a first embodiment of the invention; Figure 2 is a perspective view of the tray in the course of erection; Figure 3 is a perspective view of the inside of one corner of the erected tray; Figure 4 is a cross-sectional view showing the relevant parts of two such trays when one is being stacked upon the other; Figure 5 is a plan view of a blank for making a tray according to a second embodiment; and Figure 6 is a perspective view of this tray in the course of erection.

Referring first to Figure 1, a blank for making a tray for storing and transporting vegetable produce such as lettuces is made of corrugated board with the flutes extending in the direction of the arrows A. The tray is of a kind intended to be hand-erected by the customer.

It comprises a base panel 1 with two end wall panels 2 hingedly connected to its shorter sides, each of such end wall panels having an end wall flap 3 hinged to it at each end. Outer side wall panels 4 are hingedly connected to the longer sides of the base, and inner side wall panels 5 are hinged to the outer ones about double hinge lines 6. Side wall flaps 7 are hinged to the ends of the inner wall panels 5.

Referring now to Figure 2, to erect a tray from the blank of Figure 1 the end wall panels 2 are firstly folded up vertically and end wall flaps 3 hinged inwardly through 90" so as to lie along the hinge lines between the base panel 1 and the outer side wall panels 4. The panels 4 are then hinged up through 90" and the inner side wall panels 5 are hinged inwardly and downwardly through 1800 about the double hinge lines 6 so that the end wall flaps 3 are received between the inner and outer side wall panels. The flaps 7 on the inner side wall panels are hinged through 90" to lie along the insides of the end wall panels. Locking lugs 8 provided at the junction between the inner side wall panels 5 and their flaps 7 are received in suitable slots 9 in the angles of the bottom corners where the base panel 1 meets the end wall panels 2 and their associated wall flaps 3.

Four stacking lugs 10 are formed as extensions of the inner side wall panels 5, being released from the board material in line with the double hinge lines 6, so that such lugs extend upwardly from the inside layer of each of the side walls when erected. In the region of the stacking lugs the side walls are partly of triple thickness due to the presence of the end wall flaps 3.

Where the flap 3 extend into the elongate slots left in the tops of the side walls by the release of the stacking lugs 10, upward extensions 11 are formed on the top edges of the flaps to lock them into the slots.

Slots 12 to receive the stacking lugs 10 of the next tray down in a stack are formed in the base panel 1. The arrangement at one of the corners of the erected tray is shown in more detail in Figure 3. Of course, all of the four corners are similar.

Referring now to Figure 4, this shows one tray being stacked upon another. One of the slots 12 in the base panel 1 receives stacking lug 10 and the top regions of the outer wall panel 4 and the wall flap 3, whilst the bottom edge regions 13 of the outer wall panel and the flap 3 become located immediately outwardly of the stacking lug when the two trays are fully interengaged, so as positively to prevent the side wall of the upper tray from moving inwardly.

Referring now to Figures 5 and 6, these show a modified tray particularly adapted for machine erection.

The arrangement of the stacking lugs is similar to that of the first embodiment. The main difference is that no flaps are provided on the ends of the end wall panels 2.

Instead, flaps 14 are additionally provided on the ends of the outer side wall panels 4. When the tray is erected the flaps 15 on the inner side wall panels 5 are folded in between the inner and outer side wall panels, to take the place of the flaps 3 of the first embodiment, and the flaps 14 on the inner side wall panels are folded around the outside of the end wall panels 2 and glued to them to hold the tray in its erected condition. The operation of the stacking lugs is exactly the same as in the first embodiment.

It will be understood that in both embodiments the direction of the flutes in the corrugated board is such that they extend vertically in both the inner and outer layers of the side walls.

Each of the embodiments of the invention illustrated in the drawings may provide a tray whose length is twice its width. It is contemplated that trays of otherwise similar structure but of square configuration could be provided, with each side of a length equal to the width of the illustrated trays. Two of such trays could then be stacked side by side on one of the illustrated trays as an alternative to stacking two similar elongate trays one upon the other. Obviously a stack of trays could then include some layers formed by only one tray, and others formed by two smaller trays. In such a stack, the stacking lugs provided on the respective trays will still interengage with the tray or trays above, in the same manner as previously described.

Claims (8)

Claims.

1. A tray or like container made of cardboard, corrugated board or similar lightweight foldable sheet material, having a base and upstanding side walls, stacking lugs being provided as integral upward extensions of at least some of said side walls, and corresponding slots or recesses being provided in the base of the tray to receive the said stacking lugs of a similar tray immediately beneath it in a stack, wherein each of the said stacking lugs is formed on the innermost sheet of a wall which is made up of at least two thicknesses of sheet material.

2. A container as claimed in claim 1, wherein each of said slots or recesses has sheet material extending along the outer side thereof to laterally engage the outside of a stacking lug of a lower tray when received in said slot or recess.

3. A container as claimed in claim 1 or claim 2, wherein the said at least two thicknesses of sheet material comprise an inner wall panel on which the said stacking lug is formed and an outer wall panel hingedly connected to said inner wall panel about two laterally spaced hinge lines at their top edges, the stacking tab being released from the area of board between the said hinge lines.

4. A container as claimed in any of claims 1 to 3, wherein the said wall is made up at least partly of three thicknesses of sheet material in the region of said stacking lug.

5. A container as claimed in claims 3 and 4, wherein the third thickness of sheet material is provided by a flap hingedly connected to another adjacent wall and extending between said inner and outer wall panels.

6. A container as claimed in claims 3 and 4, wherein the third thickness of sheet material is provided by a flap hingedly connected to the end of the said outer wall panel and folded in between the two panels.

7. A container as claimed in claim 1, substantially as hereinbefore described with reference to Figures 1 to 4 or Figures 5 and 6 of the accompanying drawings.

8. A blank for making a container as claimed in any of the preceding claims.