EP0682628B1

EP0682628B1 - Enclosed bottle carrier

Info

Publication number: EP0682628B1
Application number: EP93917343A
Authority: EP
Inventors: James T. Stout; James B. Demaio
Original assignee: Mead Corp
Current assignee: Mead Corp
Priority date: 1992-07-30
Filing date: 1993-07-26
Publication date: 1998-09-30
Anticipated expiration: 2013-07-26
Also published as: ES2121093T3; CZ286857B6; HUT71773A; PL306816A1; NZ254665A; CA2141310C; BR9306790A; AU4688593A; ATE171687T1; DE69321370D1; JPH07509429A; SK9595A3; SG46468A1; DK0682628T3; JP3182729B2; AU674872B2; MX9304637A; HU220283B; EP0682628A1; WO1994003374A1

Abstract

A bottle carrier for packaging and gripping in a taut fashion a plurality of bottles includes top (1), bottom (47) and side walls, each side wall having a substantially vertically disposed bottom portion (21, 35) and an inwardly inclined top portion (6, 8) foldably joined to the bottom portion to form a tubular structure, top end panels (2, 4) foldably joined to each end edge of the top wall together with a bottom end panel (49, 51) foldably joined to each of the bottom wall and secured in overlapping relation with the associated top end panel. A first collapsible web is (15, 17) foldably joined to each end edge of each top end panel (2, 4) and to the end edge of each of the inwardly inclined top wall portion (6, 8). A yieldable fold line (30, 31) formed in each collapsible web (15, 17) extends from the adjacent corner of the top wall downwardly in angular relation to the adjacent end edge of the associated inwardly inclined top wall portion (6, 8).

Description

This invention relates to carriers for packaging which are specially designed to prevent bottle breakage due to collision between adjacent bottles.

US patent 3 904 036 owned by the proprietor of this invention discloses a fully enclosed bottle container and includes a so called false score formed in the bottom wall. The end closure structure including upper and lower end flaps is inwardly tapered so that the top wall is of a shorter longitudinal dimension than the bottom wall. There is a web structure which interconnects upper and lower end flaps with each end edge of each side wall.

Canadian patent 1 166 211 owned by the proprietor of this invention discloses a carton for beverage containers comprising a series of panels connected together to form a tubular structure. The tubular structure has a pair of end closure flaps which are foldable inwardly across the end and into an overlapping relationship. The carton includes a gusset panel connected to the side walls and end flaps.

One aspect of the present invention provides a bottle carrier comprising top, bottom, and side walls each side wall comprising a bottom portion and an inwardly inclined top portion, said top, bottom and side walls being interconnected to form a tubular structure, a top end panel foldably joined to an end edge of said top wall, a first web structure foldably joined to said top end panel and to an adjacent end edge of an inwardly inclined top portion, characterised in that said first web structure has a yieldable fold line extending from said top wall and disposed in angular relation to the adjacent end edge of the associated inwardly inclined top portion so as to more closely conform to the neck of the associated corner bottle.

According to an optional feature of this aspect of the invention, a bottom end panel may be foldably joined to an end edge of the bottom wall and secured in overlapping relation with an associated top end panel, and/or wherein a second web structure is foldably joined to an adjacent end edge of a side wall bottom portion.

According to another optional feature of this aspect of the invention, the second web structure may be partially separated by a slot from an associated first web structure and interconnected therewith by a small panel.

According to yet another optional feature of this aspect of the invention, a first yieldable fold line may be formed in said second web structure and preferably disposed in coaxial relation with the yieldable fold line in the first web structure, and/or wherein the bottom end panel is secured to the adjacent second web structure.

According to a further optional feature of this aspect of the invention, a second yieldable fold line may be formed in the second web structure and may extend downwardly from an upper corner of the side wall bottom portion and in converging relation to the first yieldable fold line.

According to yet a further optional feature of this aspect of the invention, a third yieldable fold line may be formed in each of the second web structures and extends from a lower outer corner of each of the second web structures upwardly and inwardly to a point of intersection with the associated one of the second yieldable fold lines to aid in gripping the body portion of the corner bottles in the carrier in a taut and stable fashion.

According to yet another optional feature of this aspect of the invention, each of the web structures may be collapsible along a fold line which extends from an outer edge thereof toward the adjacent top corner of the carton.

According to another optional feature of this aspect of the invention, a second web structure may comprise a first web panel foldably joined to the bottom portions of the side walls and folded inwardly into engagement with the adjacent corner bottles and second web panels may be joined to the bottom portion of the side walls and the second web panels being defined by pairs of fold lines each of which pairs diverges upwardly and which terminate adjacent the upper ends of the first and second web panels. Preferably, the first and second web panels being related to each other so as to maintain the first web panels in engagement with the adjacent corner bottles and preferably wherein the second web panel is disposed astride a corner of the carrier.

According to another optional feature of this aspect of the invention, the lower ends of the first web structure and the adjacent upper end of the second web panel may be disposed in extension of the fold lines which define the junction between the top and the bottom portions of the side walls. Preferably, a lower end portion of the first web structure portion and an upper end panel of the second web panels are separated by cut lines.

Another aspect of the invention provides a carrier for bottles arranged in a side by side rectilinear group comprising a top wall, a bottom wall, and side walls, each side wall having a bottom portion and a top side wall portion having an end edge, the top, bottom and side walls being interconnected to form a tubular structure, a top end panel foldably joined to each end edge of the top wall along a fold line which extends between opposite corners of the carton characterised in that a first web panel foldably joined to one side edge of each of the top end panels, a second triangular web panel foldably joined to an end edge of the adjacent side wall top portion and to the adjacent edge of the first web panel along fold lines which diverge downwardly to define at least in part a third edge of the second triangular web panel so as to position the second triangular web panel astride the adjacent corner of the carrier and to cause the second web panel to engage the neck of the adjacent corner bottle and to impart a taut inward force thereto, a third web panel foldably joined to the adjacent end of the bottom portion of the side wall and folded inwardly into engagement with the large bottom portion of the adjacent bottle, and a fourth web panel defined by a pair of fold lines which diverge upwardly from a point on the end edge of the third web panel and which terminate adjacent the junction between the bottom portion of the adjacent side wall and the associated side wall top portion to impart an inward taut force to the large bottom portion of the adjacent corner bottle.

According to a further optional feature of this aspect of the invention, the fourth web panel may be of generally triangular configuration defined by the pair of lines which diverge upwardly and by a third line which may extend for a portion of the distance between the upper extremities of the pair of lines which diverge upwardly, and preferably wherein the remainder of the distance between the upper extremities of the pair of lines which diverge upwardly is a cutaway line.

According to yet a further optional feature of this aspect of the invention, the point of intersection of the downwardly diverging sides of each of the fourth web panels may also coincide with the fold line between each of the third web panels and with each end of each of the bottom portions of each side wall the fourth web panel being disposed astride the adjacent corner of the carrier, and preferably wherein the cutaway line affords clearance for its adjacent edges whereby the edges move into engagement with each other thereby to impart an inward force to the adjacent third web panel.

According to another optional feature of this aspect of the invention, the side wall top portions may be upwardly and inwardly inclined and wherein the end edge of the adjacent inwardly inclined side wall top portion is substantially perpendicular to the bottom edge of the inwardly inclined side wall top portion.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:-

Figure 1 is a plan view taken from the inside of a blank formed according to this invention;

Figures 2 and 3 show stages of folding through which the blank of Figure 1 is manipulated so as to form a set up and closed carrier as shown in Figure 4;

Figure 5 shows the carton partially closed and with areas broken away; and

Figure 6 shows the carton from one end which is fully enclosed;

Figures 7 to 12 show a modified form of the invention in which Figure 7 is a perspective view of the fully set up and enclosed carrier;

Figure 8 is a plan view of a blank from which this modified carrier is formed;

Figure 9 is an enlarged fragmentary view of the top wall and adjacent panels of this modified carrier as viewed from the inside;

Figure 10 is a view similar to Figure 7 but which shows the near end of the modified carrier with the end closure panels and the web structures in partially set up condition;

Figure 11 is a cross sectional view of the top wall taken along the line 11-11 of Figure 10; and

Figure 12 is a view which shows carrier parts as they appear during closing of an end of this modified version.

With reference to Figure 1 the top wall of the carrier is designated by the numeral 1. Top end panel which is designated by the numeral 2 is foldably joined to top wall 1 along fold line 3 and top end panel 4 is foldably joined to top wall 1 along fold line 5. Side wall top portion is designated by the numeral 6 is foldably joined to top wall 1 along fold line 7. On the other side of the carrier, side wall top portion 8 is foldably joined to top wall 1 along fold line 9. Tear strip 10 having a finger gripping pull tab 11 is formed in side wall top portion 6 and extends into top wall 1 as indicated at 10a and 10b. On the other side of the carrier, tear line 12 and pull tab 13 are formed in the side wall top portion 8 and extends into the top wall as designated at 12a and 12b. Hand gripping handle is formed in top wall 1 and designated generally at 14.

Collapsible web structure 15 is foldably joined to the side wall top portion 6 along fold line 16 and similarly collapsible web structure 17 is foldably joined to the upper inwardly inclined side wall top portion 6 along fold line 18. Collapsible web structure 15 is formed with a fold line 19 along which

parts

19a and 19b are foldable when the structure 15 is collapsed during set up of the carrier. In similar fashion, collapsible web structure 17 includes a fold line 20 along which panels 20a and 20b are foldable into flat face contacting relation when the carrier is set up.

Side wall bottom portion is designated at 21 and is foldably joined to inwardly inclined side wall 6 along fold line 22. Web structure 23 is foldably joined to side wall bottom panel 21 along fold line 24. Web structure 23 includes weakened

lines

25, 26 and 32 which facilitate manipulation of

panel elements

25a, 26a and 26b which aid in gripping the bottles and tend to prevent breakage.

In like fashion, web structure 27 is foldably joined to side wall bottom portion 21 along fold line 28 and includes weakened

lines

29, 30a and 33 which facilitate gripping of bottles in a taut fashion.

According to one feature of this invention, a yieldable fold line 30 is formed in collapsible web structure 15 and a yieldable fold line 31 is formed in collapsible web structure 17 as shown in FIG. 1.

According to another feature of this invention, the yieldable fold line 30 is extended into the collapsible structure 23 along a fold line 32 which is coaxially disposed relative to fold line 30. In like fashion, the yieldable fold line 31 is extended into the collapsible structure 27 along fold line 33 which is coaxially disposed relative to yieldable fold line 31. These

yieldable fold lines

30, 32, 31 and 33 constitute an improvement whereby bottles packaged within the container are securely gripped so as to hold the bottles in a taut and secure condition.

On the other side of the carrier, a side wall bottom portion is designated by the numeral 35 and is foldably joined to the side wall top portion 8 along fold line 36. Collapsible web structure generally designated at 37 is formed and foldably joined to one end 38 of side wall top portion 8. In like fashion, collapsible web structure 40 is foldably joined to the opposite end of side wall top portion 8 along fold line 41.

Collapsible web structures

37 and 40 are formed in the same manner as are the

collapsible structures

15 and 17 previously described.

Also a web structure generally designated at 42 is foldably joined to side wall bottom portion 35 along fold line 43 and is formed in a manner identical to the manner in which collapsible structure 23 is formed. Web structure 42 is partially separated from collapsible web structure 37 by a slot 42a and is interconnected therewith by a small rectangular panel 42b. In like fashion, web structure 44 is foldably joined to side wall bottom portion 35 along fold line 45 and collapsible structure 44 is identical to collapsible structure 27 previously described. Web structure 44 is partially separated from collapsible web structure 40 by a slot 44a and is interconnected therewith by a small rectangular panel 44b.

Bottom wall 47 is foldably joined to the side wall bottom portion 35 along fold line 48 and bottom end panel 49 is foldably joined to bottom wall 47 along fold line 50. In like fashion, bottom end panel 51 is foldably joined to bottom wall panel 47 along fold line 52. A glue flap 53 is foldably joined to an edge of bottom wall 47 along fold line 54.

In order to manipulate the blank of FIG. 1 into the condition shown in FIG. 2, side wall bottom portion 21 is simply elevated and folded forwardly along fold line 22 and

web structures

23 and 27 are folded from their positions shown in FIG. 1 to the position shown in FIG. 2.

The carton as shown in FIG. 2 is manipulated into the collapsed condition shown in FIG. 3 by simply elevating the side wall top portion 6, top wall 1 and side wall top portion 8 along with side wall bottom panel 21 and folding downwardly along the fold line 36 following the application of glue to glue flap 53. This folding operation causes the

web structure

37 and 40 as well as the

web structure

15 and 17 to overly their associated

web structures

42 and 44 and 23 and 27.

In order to set the carrier up from its collapsed condition as shown in FIG. 3 into its fully completed condition as shown in FIG. 4, the top wall 1 is elevated so that the side

wall bottom portions

21 and 35 are substantially vertically disposed relative to the bottom wall 47. Following loading of the bottles into the carrier, from one or both ends, the

structures

15, 23, 17, 27, 37, 42, 40 and 44 are folded inwardly into set up condition. The

top end panels

2 and 4 are folded downwardly along the

fold lines

3 and 5 respectively while the

bottom end panels

49 and 51 are folded along

fold lines

50 and 52 to cause the adhesive flap 2a on top end panel 2 and the adhesive flap 4a formed in top end panel 4 to become adhered to the outer edges of

bottom end panels

49 and 51 and the fully loaded and set up carton appears as shown in Figure 4. Figure 5 shows the carrier from one end with parts broken away so as to show weakened

fold lines

30, 32, 25 and 26.

Turning now to the modified form of the invention, reference is made to the blank illustrated in Figure 8 wherein the top wall is designated by the numeral 101. Parts of the carton handle structure are generally designated by the numeral 102 and

U-shaped tabs

103, 104, 105 and 106 are struck from the top wall 101. Top end panel 107 is foldably joined to top wall 101 along fold line 108 and top end panel 109 is foldably joined to top wall 101 along fold line 109a.

In the preferred embodiment, the bottom portion of one side wall is designated by the numeral 110 and an inwardly inclined side wall top portion 111 is foldably joined to the side wall bottom portion 110 along a fold line 112 and side wall top portion 111 is foldably joined to top wall 101 along fold line 113. In an alternate embodiment (not shown), side wall top portion 111 is not inwardly inclined, but rather is coplanar with side wall bottom portion 110. In such a case, fold line 112 may be omitted, and both portions may be formed as a single wall panel.

Conventional tear strips 114 and 115 are struck from side wall top portion 111 and from top wall 101.

Suitable web structure formed according to this invention includes a first web panel 116 foldably joined to top end panel 107 along fold line 117. A fold line 180 interrupts first web panel 116, extending from an outer edge toward the adjacent top corner of the carton. A second triangular web panel 118 is foldably joined to first web panel 116 along fold line 119. Second triangular web panel 118 is foldably joined along fold line 120 to the adjacent end of the inwardly inclined side panel top portion 111. Fold line 120 is substantially perpendicular to fold line 112, and substantially vertical when the carton is set up.

Third web panel 122 is foldably joined to the side wall bottom portion 110 of along fold line 123. Fold line 123 is substantially perpendicular to fold line 112, substantially parallel to and offset from fold line 120, and when the carton is set up, substantially vertical. A fourth web panel 124 is of a triangular configuration and is defined by weakened

fold lines

125 and 126 which diverge upwardly from a point 127 on fold line 123. Adjacent parts of second triangular web panel 118 coincide with

corresponding fold lines

125 and 126 of the fourth web panel 124. A cutaway area 130 allows the adjacent parts of second triangular web panel 118 and a fourth triangular web panel 124 to move into abutment with each other so as to facilitate manipulation of the web structures during a carrier set up and loading operation. As may be necessary to achieve proper folding, cutaway area 130 may extend inwardly completely to fold

lines

120 and 126, or may extend only partially thereto as shown. Cutaway area 131 also aids in manipulation of the webs during a carrier loading operation.

In the preferred embodiment, a bridge portion 132 is foldably interconnected between first and

third web panels

116 and 122 to assist

infolding panels

116 and 122 following carrier loading, and in maintaining the panels in position during subsequent gluing of the carrier ends. If desired, however, it is possible to omit bridge portions 132, whereby cutaway areas 131 take the form of notches rather than openings, particularly if cutaway areas 130 extend inwardly only partially toward

fold lines

120 and 126.

The angular relationship between the third and fourth web panels 122,124 is preferable such that the third web panel 122 extends inwardly at a right angle to the side wall bottom portion 110 and presents a flat and substantially vertical surface for gluing when the bottom end panel 144 is folded into overlapping face contacting relationship therewith. In addition, fourth web panel 124 helps to maintain the third web panel 122 in engagement with the lower portions of the adjacent corner bottles.

Web structure at the other end of the carrier is identical to that just described and includes first web panel 116, second triangular web panel 118, third web panel 122 and fourth web panel 124.

The lower edge of the bottom portion 110 of one side wall is foldably joined to the bottom wall 136 along fold line 135.

Openings

137, 138, 139, 140, 141 and 142 are formed in bottom wall 136 and facilitate manipulation of the carrier during feeding and setting up operations. Bottom end panel 144 is foldably joined to bottom wall 136 along fold line 145 and bottom end panel 146 is foldably joined to bottom wall 136 along fold line 147.

The remaining side wall structure as well as the web structures previously described are identical to those shown in FIG.8 and a detailed description of these parts is not deemed necessary. The same numerals are applied to designate both sets of parts.

In order to interconnect the opposite ends of the blank as shown in FIG. 8 to form a tubular enclosure, lap panel 150 is foldably joined to the second side panel top portion 111 along fold line 151 and end panel 152 is foldably joined to lap panel 150 along fold line 153. At the other side of the blank end panel 154 is foldably joined to panel 150 along fold line 155.

U-shaped cutouts

156 and 157 are positioned as shown in FIG. 8.

In order to set the carrier up from the condition shown in FIG. 8 to that shown in FIGS. 7 and 10, an application of glue is made to reinforcing panel 158 as indicated by stippling in FIG. 8. Thereafter the reinforcing panel 158 is elevated and folded toward the right along fold line 159. This operation of course causes the reinforcing panel 158 to become adhered to the inner surface of the panel 150. Thereafter panels 111 and 116 together with

panels

150, 152 and 154 are elevated and folded toward the left along the right hand fold line 112. An application of glue is then made to

panels

150, 152 and 154, following which opposing side panels 111 and, 116, and

panels

101, 107 and 109 are elevated and folded toward the right along the left fold line 112 to cause panel 150 to become adhered to the inside surface of carton handle structure 102, as shown in FIG. 9.

The carton may then be set up into open ended condition and loaded through one or both ends. The top and bottom end panels are secured together by glue shown as stippling in FIG. 12. The various web structures are manipulated into fully set up condition and the carton then appears in completed form as shown in FIG. 7.

Access to the contents of the carrier may be had by simply rupturing the tear lines such as 114 and 115 to gain access to the packaged bottles. If bottle return is desired, the empty bottles may be reinserted into the carrier and returned.

Claims

A bottle carrier comprising top (1;101), bottom (47;136), and side walls (6,8,21,35; 110, 111), each side wall comprising a bottom portion (21,35; 110) and an inwardly inclined top portion (6,8;111), said top, bottom and side walls being interconnected to form a tubular structure, a top end panel (2,4;107,109) foldably joined to each end edge of said top wall (1;101), a first web structure (15,17,37,40;133) foldably joined to each top end panel (2,4;107,109) and to an adjacent end edge (16,18,33,41;120) of each inwardly inclined top portion (6,8,111), characterised in that said first web structure (15,17,37,40;133) has a yieldable fold line (30,31;119) extending from said top wall (1;101) and disposed in angular relation to the adjacent end edge (16,18,38,41;120) of the associated inwardly inclined top portion (6,8;111) so as to more closely conform to the neck of the associated corner bottle.
A bottle carrier according to claim 1 further comprising a bottom end panel (49,51;144,146) foldably joined to an end edge (50,52;145,147) of said bottom wall (47;136) and secured in overlapping relation with an associated top end panel (2,4,107,109), and/or wherein a second web structure (23,27,42,44;134) is foldably joined to an adjacent end edge (24,28,43,45,123) of a side wall bottom portion (21,35;110).
A bottle carrier according to claim 2 wherein the second web structure (23,27,42,44;134) is partially separated by a slot (42a,44a;130,131) from an associated first web structure (15,17,37,40;133) and interconnected therewith by a small panel (42b,44b,132).
A bottle carrier according to claim 2 or claim 3, wherein a first yieldable fold line (32,33) is formed in said second web structure (23,27,42,44) and preferably disposed in coaxial relation with said yieldable fold line (30,31) in said first web structure (15,17,37,40), and/or wherein the bottom end panel (49,51) is secured to the adjacent second web structure (23,27,42,44).
A bottle carrier according to claim 4 wherein a second yieldable fold line (25,30a) is formed in said second web structure (23,27,42,44) and extends downwardly from an upper corner of said side wall bottom portion (21,35) and in converging relation to said first yieldable fold line (32,33).
A bottle carrier according to claim 5 wherein a third yieldable fold line (26,29) is formed in each of said second web structures (23,27,42,44) and extends from a lower outer corner of each of said second web structures (23,27,42,44) upwardly and inwardly to a point of intersection with the associated one of said second yieldable fold lines (25,30a) to aid in gripping the body portion of the corner bottles in the carrier in a taut and stable fashion.
A bottle carrier according to any preceding claim wherein each of said web structures (15,17,37,40;23,27,42,44;133,134) is collapsible along a fold line (19,20, 180) which extends from an outer edge thereof toward the adjacent top corner of the carton.
A bottle carrier according to any of claims 1 to 3 wherein said second web structure comprises a first web panel (122) which is foldably joined to the bottom portions (110) of said side walls and folded inwardly into engagement with the adjacent corner bottles (B1,B3) and second web panels (124) which are joined to said bottom portion (110) of said side walls and said first web panels (122) and defined by pairs of fold lines (125,126) each of which pairs diverges upwardly and which terminate adjacent the upper ends of said first and second web panels (122,124), said first and second web panels (122,124) being related to each other so as to maintain said first web panel (122) in engagement with the adjacent corner bottles (B1,B3) and preferably wherein said second web panel (124) is disposed astride a corner of said carrier.
A bottle carrier according to claim 8 wherein the lower ends of said first web structure (133) and the adjacent upper end of said second web panel (124) are disposed in extension of said fold lines (125,126) which define the junction between said top and said bottom portions (111,110) of said side walls and preferably wherein a lower end portion of said first web structure (133) portion and an upper end portion of said second web panel (124) are separated by cut lines.
A carrier for bottles arranged in a side by side rectilinear group comprising a top wall (101), a bottom wall (136), and side walls (111,110), each side wall having a bottom portion (110) and a top side wall portion (111) having an end edge, said top, bottom and side walls being interconnected to form a tubular structure, a top end panel (107,109) foldably joined to each end edge of said top wall (101) along a fold line (108,109a) which extends between opposite corners of the carton characterised in that a first web panel (116) foldably joined to one side edge of each of said top end panels (109), a second triangular web panel (118) foldably joined to an end edge of the adjacent side wall top portion (111) and to the adjacent edge of said first web panel (116) along fold lines (119,120) which diverge downwardly to define at least in part a third edge of said second triangular web panel (118) so as to position said second triangular web panel (118) astride the adjacent corner of the carrier and to cause said second web panel (118) to engage the neck of the adjacent corner bottle (B1,B3) and to impart a taut inward force thereto, a third web panel (122) foldably joined to the adjacent end of said bottom portion (110) of the side wall and folded inwardly into engagement with the large bottom portion of the adjacent bottle (B1,B3), and a fourth web panel (124) defined by a pair of fold lines (125,126) which diverge upwardly from a point on the end edge of said third web panel (122) and which terminate adjacent the junction between said bottom portion (110) of the adjacent side wall and the associated side wall top portion (111) to impart an inward taut force to the large bottom portion of the adjacent corner bottle (B1,B3).
A bottle carrier according to claim 10 wherein said fourth web panel (124) is of generally triangular configuration defined by said pair of lines (125,126) which diverge upwardly and by a third line (112) which extends for a portion of the distance between the upper extremities of said pair of lines (125,126) which diverge upwardly, and preferably wherein the remainder of the distance between the upper extremities of said pair of lines which diverge upwardly is a cutaway line.
A bottle carrier according to claim 10 or claim 11 wherein the point of intersection (127) of said downwardly diverging sides of each of said fourth web panels (124) also coincides with the fold line (123) between each of said third web panels (122) and with each end of each of said bottom portions (110) of each side wall said fourth web panel (124) being disposed astride the adjacent corner of the carrier, and preferably wherein said cutaway line affords clearance for its adjacent edges whereby said edges move into engagement with each other thereby to impart an inward force to the adjacent third web panel (122).
A bottle carrier according to any of claims 9 to 11 wherein said side wall top portions (110) are upwardly and inwardly inclined and wherein said end edge (120) of the adjacent inwardly inclined side wall top portion (110) is substantially perpendicular to the bottom edge (112) of said inwardly inclined side wall top portion (110).