Folding corrugated board carton

Abstract: A rigid folding carton (10) suitable for the shipping of goods and their point of purchase display is formed from a one-piece blank of corrugated board which possesses at least one strength-enhancing element 23 positioned at the juncture of any two separate wall panels 11b, 12b and/or the juncture of any wall panel and associated top and/or bottom flap member and extending for substantially the full length of said juncture.

Description: BACKGROUND OF THE INVENTION This invention relates to a method of assembling a carton and to a rigid folding carton, container, or box, formed from a one-piece blank of corrugated board and which is suitable for both the shipping and display of its contents. More particularly, this invention relates to such a carton possessing corner gusset elements extending substantially the full height of the expanded carton, said gusset elements imparting significantly increased vertical crush strength to the carton compared with the crush strength of essentially the same carton but one lacking said gusset elements. A common type of folding, expandable, or knockdown carton is formed from a single blank of foldable corrugated board material and possesses four wall panels, the fourth of which possesses a tab, or strip, to provide a surface of attachment for an adjacent portion of the first wall panel, a bottom flap hingedly connected to the bottom of each of the four wall panels and a top, cover, or lid flap hingedly connected to the top of each of the four wall panels such that upon expansion of the carton, the four bottom and four top flaps come together to form, respectively, the bottom and the top, cover, or lid, of the carton. The vertical crush strength of the aforedescribed common folding corrugated board is relatively modest and care must be taken to avoid vertically stacking so many of the filled cartons as will exceed the vertical crush strength of the individual units. A number of arrangements are available for increasing the vertical crush strength of a folding container beyond the limits of the ordinary corrugated board carton. One of them, referred to as internal packaging, involves the use of die-cut corrugated board elements for providing additional crush strength. The manufacture of internal packaging is relatively labor intensive and involves greater material costs, factors which have tended to limit its application. Other expedients which can be used to achieve increased crush strength include modifying such parameters of corrugated board construction as the weight of the paperboard and simply multiplying the layers of corrugated board, e.g., to provide a double-wall, triple-wall, etc., structure. Yet another arrangement for increasing vertical crush strength in a corrugated board carton lies in the provision of two, three or more separate pieces from which the carton blank is fabricated. The specialized nature of the carton and the fact that two or more separate components are involved in its construction accounts for the limited application of this approach to carton design and manufacture. Expensive machinery is required for the assembly of a multi-piece carton and relatively low manufacturing rates, e.g., 1,000 units per hour and even less in the larger carton sizes, is fairly typical. Unsightly glued flaps on external panels, readily visible coarse perforated scores and a lack of full panels which might otherwise be used to effectively display product identification are among the negative characteristics of this type of container which tend to militate against its use for point of purchase displays. Each of these solutions to the problem of inadequate vertical crush strength exacts a considerable economic penalty. In addition, the bulk of the corrugated board required to achieve the desired increased vertical crush strength makes machining of the board more difficult and detracts from its overall appearance, an obstacle to its use in cartons intended for point of purchase display. There is disclosed in FR-A-1 135 252 a blank for a carton in which closure flaps along the longitudinal edges of the blank have edge portions which are disposed edge-to-edge in successive flaps. The edge portions have to be folded away so as to form external double thickness reinforcement strips, after such folding. External corner gussets are likewise formed by folding intermediate portions of the blank. This proposal suffers from shortcomings in terms of its requirement for the external folding of the edge portions of the closure flaps, the consequential inability of these flaps to co-operate with the gussets, which are in any case located externally and therefore tend to open and not remain in a strong tightly-folded configuration. All these factors lead to an insufficient rigidity which can be seen to arise from a lack of co-operation between the external folded structures and the main structural panels of the carton. The pre-characterising portions of claims 1 and 9 of the invention are based on the disclosure in this prior specification and the characterising features of said claims provide a means for mitigating these shortcomings. There is disclosed in US-A-2 573 524 a foil container for use in packaging milk and the like. The blank for the container is made up wholly of a metallic foil and in order to provide the container with additional rigidity, external gussets are provided by folding intermediate portions of the blank. The strength or rigidity of the container is stated to be greatest where the gussets have a rolled external form. This proposal provides insufficient rigidity in relation to cartons of the kind with which the present invention is concerned due in part at least to the absence of any co-operation between the closure flaps of the blank and the external reinforcement gussets. There is disclosed in GB-A-1 022 718 a liquid container of prismatic form having stiffened edges. The stiffening is provided by V-shaped folds. The folds are arranged to open under pressure during use and extend into the closure flaps. An object of the present invention is to provide a method of assembling a carton from a blank therefor, and an assembled carton, offering improvements in relation to one or more of the above-identified shortcomings of the prior art, and according to the invention there is provided such a method and a carton as defined in the accompanying claims. In an embodiment of the present invention, a rigid folding carton suitable for the shipping of goods and their point of purchase display is formed from a one-piece blank of corrugated board which possesses at least one structural strength-enhancing element positioned at the juncture of any two separate wall panels and/or the juncture of any wall panel and associated top and/or bottom flap member and extending for substantially the full length of said juncture. The expression "gusset element" as used herein and in the appended claims refers to a vertical crush strength-enhancing structural element positioned at the juncture, i.e., the corner, of two adjacent wall panels and which can be formed from a one-piece carton-forming blank. As a result of the corner gusset elements which impart great vertical crush strength, cartons according to this invention possess a number of advantages compared with known corrugated board containers such as those described above. In addition to a capability for accepting superior display graphics, the one-piece cartons are simpler to manufacture, use less material in their construction and minimize waste. For example, where an average of 1,000 units per hour of the multi-piece carton referred to above is typical, 5,000 units per hour of the present carton blanks is readily achievable for a comparable investment in machinery and labor. Since common manufacturing practice allows for 10% production over, and 5% production less, than the stated amount of an order, the practical consequence of such a situation is to fix the actual number of units of a multi-piece carton which are available for filling as the lowest number for a particular carton component shipped. For example, for an order of 100,000 units comprising individual pieces A, B and C, it would be usual to ship, say, 98,000 pieces A, 107,000 pieces B and 110,000 pieces C, the number of cartons available for filling thus being 98,000 (other possible losses not being taken into account). The "extra" pieces of B and C would be warehoused to balance future production runs assuming, of course, there were no carton design changes which would render them useless. In the case of the one-piece carton blank from which the carton is made according to this invention, shipment of 98,000 carton blanks would result in that number of blanks being available for filling, no more and no less. And, unlike a multi-piece carton, the different pieces of which must be shipped on different skids and then assembled on-site employing fairly expensive machinery, the single-piece carton blank herein is easily shipped and expanded utilizing relatively low-cost, high production volume equipment. For a given volume, the corner-gusseted carton of the present invention may utilize a good deal less, e.g., approximately 20% by weight less, material than a conventional carton for an equivalent degree of vertical crush strength. For example, the carton of this invention can utilize 150 pound test corrugated board compared with 200 pound test board for a known type of carton to provide a carton of equivalent size but much greater vertical crush strength than the latter. The low cost and aesthetically pleasing appearance of the high vertical crush strength folding corrugated board carton of this invention make it an ideal shipping and point of purchase display container for a wide variety of consumer goods where vertical stacking of numerous units is likely to be encountered. BRIEF DESCRIPTION OF THE DRAWINGS In the attached figures of drawing in which like reference numerals designate like elements throughout: Fig. 1 illustrates, in plan view, a folding carton blank from which a carton is made in accordance with the invention possessing a single gusset element for each of the four corners of the carton assembled therefrom; Figs. 2 and 3 illustrate, in plan view, the folding and the gluing, respectively, of the fourth single gusset element-forming panel of the folding carton blank of Fig. 1; Fig. 4 illustrates, in plan view, the details of construction of the first corner gusset element; Fig. 5 illustrates, in plan view, a folding carton blank from which a carton is made in accordance with the invention possessing a double gusset element for each of the four corners of the carton assembled therefrom; Figs. 6 and 7 illustrate, in plan view, the folding and the gluing, respectively, of the fourth double gusset element-forming panel of the folding carton blank o Fig. 5; and, Fig. 8 is a three-dimensional view of a carton assembled from the blank of Fig. 1 with a portion of the carton cut away to show the fourth corner gusset element illustrated in Fig. 4. DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in Figs. 1-4, there is provided in accordance with this invention a folding carton blank shown generally at 10 formed from a single sheet of corrugated board of rectangular shape possessing four wall panels 11a and 11b corresponding to left and right side wall panels, respectively, and 12a and 12b, corresponding to the front end wall and rear end wall panels, respectively. The wall panels are joined together through second, third and fourth corner gusset element-forming panels 13, 14 and 15, respectively, which are subdivided along the lines of the perforations shown into sub-panels 13a, 13b, 14a, 14b, 15a and 15b, respectively. The free end of wall panel 11a is provided with a first corner gusset element-forming first extension panel 16a and in similar fashion, the free end of wall panel 12b is provided with a first corner gusset element-forming second extension panel 16b. Panels 13, 14, 15, 16a and 16b are shown to be coextensive with the height x of the wall panels so as to achieve the maximum vertical crush strength but can be somewhat less than dimension x and still impart substantial vertical structural strength to the assembled carton, since a closure flap must still directly contact the end edges of an adjacent internal gusset. Carton blank 10 possesses top closure flaps 17a and 17b, top dust flaps 18a and 18b, bottom closure flaps 19a and 19b and bottom dust flaps 20a and 20b hingedly connected to their respective wall panels. To assemble carton blank 10 into a carton which is ready for filling, a suitable adhesive such as any of those known or used for the joining of corrugated board surfaces is applied to the top surfaces of first extension panel 16a and each of sub-panels 13a, 14b and 15a and to the bottom surfaces of second extension panel 16b and each of sub-panels 13b, 14a and 15b. The carton blank is then folded along the solid lines and perforations shown to form a rectangular box-shaped unit 10a as shown in Fig. 8. Fourth corner gusset element 23 shown in Fig. 3 is formed by folding panel 15 in the manner shown in Fig. 2. Contact of sub-panel 15a with the adjacent portion of wall panel 11b and contact of sub-panel 15a with sub-panel 15b forms single corner gusset element 23. Formation of the second and third corner gusset elements (shown unassembled in Fig. 1) are accomplished in a manner similar to that of fourth corner gusset element 23. The structure of first corner gusset element 21 is shown in Fig. 4 but unlike the second, third and fourth corner gusset elements, the components of the first corner gusset element are provided by extension panels at both ends of the blank. Thus, panel extension 16a is folded over and adhesively joined at its underside to a portion of wall panel 11a and extension panel 16b is folded and adhesively joined to the back, or underside, surface of extension panel 16a to provide the finished gusset element and the closure of the four wall panels. In the embodiment of the invention shown in Figs. 5 to 7, the extension panel provided at the free end of wall panel 12b and gusset-forming panels 13, 14 and 15 of carton blank 10′ have been modified to provide a greater number of sub-panels, i.e., 13a, 13a′, 13b, 13b′, 14a, 14a′, 14b, 14b′, 16b, 16b′ and 16b″ which, when folded and joined in the manner indicated in Figs. 6 and 7, form double corner gusset elements. Application of adhesive is to the top of extension panel 16a and sub-panels 13a and 13b, 14a and 14b, 15a and 15b and 16b″ and to the bottom of extension sub-panels 16b and 16b′ and sub-panels 13a′ and 13b′, 14a′ and 14b′ and 15a′ and 15b′. Formation of a double corner gusset element is shown in Figs. 6 and 7. Thus, e.g., panel 15 is folded and adhesively joined in the manner shown to provide fourth double corner gusset element 23′. Formation of first, second and third double corner gusset elements is accomplished in a manner analogous to that described above in connection with the carton of Figs. 1 to 4. While it is readily apparent that the carton blank herein can be assembled into a finished carton by hand, the invention contemplates the use of known and conventional high production rate gluing and folding machinery for final assembly of the blank into container units ready for filling. It will be noted that the carton blank of this invention and the resulting carton do not allow for the placement of a gusset element anywhere other than at a corner, i,e., anywhere other than at the juncture of two panels. Stated another way, the carton of the present invention excludes any arrangement wherein a gusset, or vertical-strengthening member, is positioned at some point along a wall panel which is at a distance away from either of its corners. This limitation is critical to the practical assembly of the carton since it is necessary that the top and bottom flaps be freely closable without the hindrance that a gusset extending across them as well as the wall panels to which they are hingedly connected would necessarily impose. In addition, for a carton possessing a knock-out section to permit display of its contents, an important embodiment of the present invention, it is necessary that the gusset elements be positioned away from the knock-out sections. In addition to the specific embodiments of the invention shown herein, numerous modifications thereof which are within the scope of the claims are also contemplated. Thus, for example, in place of the four-sided carton shown, a carton can be provided with three walls or more than four walls with each corner possessing a vertical crush strength-enhancing gusset element. Gusset elements of varying thicknesses of corrugated board can be provided by varying the gluing and folding pattern of the gusset-forming panels within the scope of the accompanying claims. However, the corner gusset elements are essentially flat in appearance, the result of being built up from folded-over layers of corrugated board as shown in the embodiments of Figs. 1-8. Individual gusset element can be joined to either adjacent panel according to the requirements of a specific design. As previously indicated, one or more wall panels can be provided with knock-out, or other otherwise removable, sections, e.g., section 210 shown in dotted outline in Fig. 1, to expose the contents of the carton for point of purchase display purposes without any appreciable loss of vertical crush strength.

Claims: A method of assembling a carton from a one-piece blank (10) of corrugated board material, the blank (10) comprising:- a) at least three side wall panels (11a, 12a, 11b, 12b) which are hingedly connected by bridging panels (13, 14, 15) and each bridging panel (13, 14, 15) including a fold line dividing the bridging panel (13a, 13b; 14a, 14b; 15a, 15b); b) at least one top closure flap and at least one bottom closure flap (17a, 18a, 17b, 18b; 19a, 20a, 19b, 20b) hingedly connected to the top and bottom marginal edges of the wall panels (11a, 12a, 11b, 12b); c) extension panels (16a, 16b) hingedly connected to the opposite ends of the end wall panels (11a, 12b) of the blank (10) to provide the joint (21) therebetween and so as to form a generally open-ended erected carton; d) said bridging panels (13a, 13b; 14a, 14b; 15a, 15b) being folded along their respective fold lines to produce rigidified gussets (23) in the erected carton; characterised in that:- e) said bridging panels (13a, 13b; 14a, 14b; 15a, 15b) and extension panels (16a, 16b) are substantially coextensive with height (X) of the wall panels (11a, 12a, 11b, 12b); f) said method comprising causing said bridging panels (13a, 13b; 14a, 14b; 15a, 15b) and said extension panels (16a, 16b) to be folded inwardly to provide internal rigidification gussets (23, 21), and the method also comprising bonding each first face (13a, 14b, 15a, 16a) of the folded material of the gussets (23, 21) to the adjacent face (13b, 14a, 15b, 16b) and bonding the gusset itself (23, 21) to an adjacent wall panel (12a, 12b, 11a, 11b); g) said method further comprising the step of folding said at least one top closure flap and said at least one bottom closure flap (17a, 18a, 17b, 18b; 19a, 20a, 19b, 20b), so that they contact the end edges of an adjacent internal gusset (23, 21). A method as claimed in claim 1, characterised in that a suitable adhesive is applied to a surface of said foldable extension panel (16a) of a first wall panel (11a), to surfaces of the bridging panels (13, 14, 15) and to a surface of said foldable extension panel (16b) of a final wall panel (12b); and said extension (16a, 16b) and bridging (13a, 13b; 14a, 14b; 15a, 15b) panels are folded to form the erected carton in such a manner that said extension panel (16a) of the first wall panel (11a) is folded 180° and joined to the wall panel (11a) of which it is an extension, the extension panel (16b) of the final wall panel (12b) is folded at an angle which is equal to 360° divided by the number of wall panels (11a, 12a, 11b, 12b) and joined to the free surface of the folded extension panel (16a) of the first wall panel (11a) to form the joint (21) therebetween, whereby the total number of said internal corner gusset elements (23, 21) is equal to the total number of wall panels (11a, 12a, 11b, 12b), and said internal vertical corner gusset elements (23, 21) impart substantially increased vertical crush strength to said carton compared to a carton of the same dimensions and same grade corrugated board lacking vertical corner gusset elements. A method as claimed in claim 1 or claim 2, characterised in that in step (f), both the bridging panels (13, 14, 15) and the extension panels (16a, 16b) are all folded at or above a plane of the blank (10) such that no folding operation takes place below this plane. A method as claimed in claim 2, characterised in that in step (f), a suitable adhesive is applied to a top surface of said extension panel (16a) of the first wall panel (11a), to top and bottom surfaces of the bridging panels (13, 14, 15) and to a bottom surface of said foldable extension panel (16b) of the final wall panel (12b). A method as claimed in claims 2 or 4, characterised in that in step (f), the adhesive is applied to: top surfaces of a first subpanel (13a) of a first bridging panel (13), a second subpanel (14b) of a second bridging panel (14) and a first subpanel (15a) of a third bridging panel (15); and bottom surfaces of a second subpanel (13b) of the first bridging panel (13), a first subpanel (14a) of the second bridging panel (14) and a second subpanel (15b) of the third bridging panel (15). A method as claimed in any one of the preceding claims, characterised in that in step (f), the bridging panels (13, 14, 15) are each folded into four subpanels (13a, 13a', 13b' , 13b; 14a, 14a', 14b' , 14b; 15a, 15a',15b',15b) and the extension panel (16b) of the final wall panel (12b) is folded into three subpanels (16b, 16b', 16b'') such that double internal corner gusset elements (23') are formed upon folding. A method as claimed in claim 6, characterised in that in step (f), the adhesive is applied to: top surfaces of the extension panel (16a) of the first wall panel (11a), the first (13a, 14a, 15a) and fourth (13b, 14b, 15b) subpanels of the bridging panels (13, 14, 15) and the third subpanel (16b'') of the extension panel (16b) of the final wall panel (12b); and the bottom surfaces of the second (13a', 14a', 15a') and third (13b', 14b', 15b') subpanels of said bridging panels (13, 14, 15) and the first (16b) and second 16b') subpanels of said extension panel (16b) of the final wall (12b). A method as claimed in any one of the preceding claims, said blank comprising at least two top and at least two bottom closure flaps (17a, 18a, 17b, 18b; 19a, 20a, 19b, 20b) hingedly connected to the top and bottom marginal edges of the wall panels (11a, 12a, 11b, 12b) wherein in step (g) said top and bottom closure flaps (17a, 18a, 17b, 18b; 19a, 20a, 19b, 20b) are folded in sequence so that at least one top closure flap and at least one bottom closure flap (18a, 18b; 20a, 20b) contact the end edges of an adjacent internal gusset (23, 21) and the adjacent flaps (17a, 17b; 19a, 19b) are then folded onto said at least one flaps (18a, 18b; 20a, 20b). An assembled rigid carton formed from a one piece blank (10) of corrugated board material comprising:- a) at least three side wall panels (11a, 12a, 11b, 12b) which are hingedly connected by bridging panels (13, 14, 15) and each bridging panel (13, 14, 15) including a fold line dividing the bridging panel (13a, 13b, 14a, 14b, 15a 15b); b) at least one top closure flap and at least one bottom closure flap (17a, 18a, 17b, 18b, 19a, 20a, 19b, 20b) hingedly connected to the top and bottom marginal edges of the wall panels (11a, 12a, 11b, 12b); c) extension panels (16a, 16b) hingedly connected to the opposite ends of the end wall panels (11a, 12b) of the blank (10) to provide a joint (21) therebetween and so as to form a generally open-ended erected carton; d) said bridging panels (13a, 13b; 14a, 14b; 15a, 15b) being folded along their respective fold lines to produce rigidified gussets (23) in the erected carton; characterised in that:- e) said bridging panels (13a, 13b; 14a, 14b; 15a, 15b) and said extension panels (16a, 16b) being folded inwardly to provide internal rigidification gussets (23) substantially coextensive with the height (X) of the wall panels (11a, 12a, 11b, 12b); and f) each face (13a, 14b, 15a, 16b) of the folded material of the gussets (23, 21) is bonded to the adjacent face (13b, 14a, 15b, 16a) and the gusset (23, 21) itself is bonded to an adjacent wall panel (12a, 12b, 11a); and g) the at least one top closure flap and the at least one bottom closure flap (18a, 18b; 20a, 20b) directly contact the end edges of an adjacent internal gusset (23, 21). A carton as claimed in claim 9, characterised in that said at least one top closure flap (17a, 18a, 17b, 18b) hingedly connected to the top of a wall panel (11a, 12a, 11b, 12b) is substantially coextensive with the length thereof (11a, 12a, 11b, 12b) and said at least one bottom closure flap (19a, 20a, 19b, 20b) hingedly connected to the bottom of one wall panel (11a, 12a, 11b, 12b) is substantially coextensive with the length thereof (11a, 12a, 11b, 12b), the at least one top closure flap (17a, 18a, 17b, 18b) connected to the tops of the wall panels (11a, 12a, 11b, 12b) and the at least one bottom closure flap (19a, 20a, 19b, 20b) connected to the bottoms of the wall panels (11a, 12a, 11b, 12b) forming respective top and bottom carton closures. A carton as claimed in claim 9 or claim 10, characterised in that at least one wall panel (11b) possesses a section (210) adapted for removal to expose the contents of the carton. A carton as claimed in any one of claims 9 to 11, characterised in that the exterior surface of each wall panel (11a, 11b, 12a, 12b) is continuously flat for substantially its full expanse. A carton as claimed in any one of claims 9 to 12, characterised in that said extension panel (16a) of a first wall panel (11a) is folded 180° and joined to the wall panel (11a) of which it is an extension, and said extension panel (16b) of a final wall panel (12b) is folded at an angle which is equal to 360° divided by the number of wall panels and joined to the free surface of said folded extension panel (16a) of the first wall panel (11a). A carton as claimed in any one of claims 9 to 13, characterised in that said bridging panels (13, 14, 15) and extension panels (16a, 16b) are folded to form double internal corner gusset elements (23'). A carton as claimed in any one of claims 9 to 14, comprising: b) at least two top and at least two bottom closure flaps (17a, 18a, 17b, 18b, 19a, 20a, 19b, 20b) hingedly connected to the top and bottom marginal edges of the wall panels (11a, 12a, 11b, 12b), and wherein at least one top closure flap and at least one bottom closure flap (18a, 18b; 20a, 20b) directly contact the end edges of an adjacent internal gusset (23, 21) and the adjacent flaps (17a, 17b; 19a, 19b) are folded onto said at least one flaps (18a, 18b; 20a, 20b).

Inventors: BATES HOWARD M, BATES, HOWARD M.
Applicants: CALPAC INC, CALPAC, INC.
Application year: 1989
Main classification: B65D5
IPC codes: B65D5