Patent Grant
8317671
1. Field of the Invention
This invention relates generally to article packaging and more specifically to the fabrication of paperboard cartons into which a plurality of articles can be packaged for transport and sale.
2. Description of the Related Art
Paperboard cartons of various design and construction have long been used by the packaging industry to package a wide variety of articles such as canned and bottled drinks, food items, detergents, and more. In general, paperboard cartons are erected or converted from paperboard blanks that are die-cut or rotary-cut from long webs of paperboard as the paperboard is drawn progressively from large rolls. Fold lines are scored in the blanks to define the various panels of the cartons and to aid in the conversion of the blanks into their final carton shapes. In some cases, such as in beer and soft drink packaging, the blanks are pre-glued and provided to packager in the form of substantially flat knocked down sleeves that are erected in a packaging machine into open ended cartons for receiving articles. In other cases, the blanks are provided in a completely flat configuration, in which case the blanks typically are folded around groups of articles and glued by the packaging machine. In either case, the conversion of blanks usually is performed at the time of packaging by specialized conversion stations that are part of large continuous packaging machines. In this way, the flat or pre-glued and knocked down paperboard blanks can be shipped economically to the packager in palletized stacks.
When making paperboard carton blanks from a web of paperboard, the web usually is pre-cut to a specified predetermined width from a wider web of paperboard stock. The pre-cutting of the web to width generally takes place at the paper mill. The width of the web in each case is dictated by the size and shape of the cartons to be made from the web and is specified to the paper mill by a carton fabricator. For example, a web of paperboard stock may have a width of 64 inches whereas a particular carton blank may require a web 48 inches wide. In such an example, a strip of paperboard 16 inches wide (or two strips that total 16 inches in width) typically will be cut from the web of paperboard stock by the paper mill to form the required 48 inch-wide web. These strips, known in the industry as “trim,” traditionally have had reduced value and in some cases are sold at low cost for secondary uses such as the making of shirt collar stiffeners used in the garment industry. In general, the creation of trim in the process of making paperboard web has long been a problem for paperboard manufacturers.
Occasionally, errors by paperboard manufacturers result in rolls of paperboard web that may be substandard for a variety of reasons and thus not usable in the fabrication of paperboard cartons. In other cases, paperboard web manufactured for a particular customer may not meet specifications and thus cannot readily be used. Such substandard and-off-spec paperboard is known in the industry as “cull” and also has had reduced value, sometimes being reconstituted into pulp for making new paper. In general, there has been little use for trim and cull in the paperboard carton making industry.
In many packaging applications, the cartons into which articles are packaged must exhibit enhanced strength at least in selected regions to contain the articles securely. This is particularly true in cases where the articles are relatively heavy and are stacked atop one another in their cartons for shipment and sale. For example, canned and bottled beverages, which typically may be packaged in groups of 6, 12, or 24, are inherently relatively heavy and typically are stacked several cartons high on pallets for shipment to retail stores. The cartons into which these beverages are packed therefore must be strong enough to hold the groups of cans or bottles securely together and to resist tearing or “blowing out” even when under the substantial weight of several layers of stacked cartons. In other applications, such as, for example, cartons of boxed fruit drinks, the cartons themselves must provide at least some of the strength and rigidity necessary to resist crushing when layers of cartons are stacked atop one another. This is because the individual drink containers lack the rigidity of bottles or cans and cannot themselves bear the entire weight of a stack of cartoned fruit drinks.
In applications such as these, traditional paperboard cartons have sometimes proven inadequate to provide the required strength and rigidity. As a result, many packagers have turned to a carton material known in the industry as micro-flute, which is a corrugated paper product. In general, micro-flute is fabricated from a core of paper material formed with a large number of relatively small corrugations sandwiched between facing sheets of flat paper. Micro-flute does tend to provide the strength and rigidity required in many packaging applications; however, it also has significant inherent problems and shortcomings including its generally higher price compared to paperboard. In addition, carton blanks made of micro-flute can be more expensive in some weights to ship than paperboard blanks because their greater thickness limits the number of blanks that can be stacked on standard sized pallet. Further, in some cases, specialized conversion machinery is required to convert the blanks to cartons, increasing the cost of the packaging process. Finally, the printing of high quality graphics on micro-flute has sometimes proven to be difficult. Thus, micro-flute has not provided a completely satisfactory solution as a carton making material in packaging applications where enhanced carton strength and rigidity is required.
Attempts have been made to improve the strength and rigidity of paperboard cartons to provide a viable alternative to micro-flute where added strength and rigidity are required. These attempts have included laminating two or more webs or sheets of standard thickness paperboard together to create thicker multi-ply paperboard from which carton blanks can be cut. However, while this approach increases the strength and rigidity of resulting cartons, it essentially results in a doubling of the paperboard required per carton and a consequent increase in material and shipping costs. Further, the formation of fold lines in and the folding of multiple ply paperboard cartons is problematic due to the added thickness of paperboard that must be folded. For these and other reasons, such multi-layer laminated paperboard has not proven to be an acceptable alternative to micro-flute.
Other attempts to provide alternatives to micro-flute have included the separate fabrication of custom stiffening inserts, which are installed in individual cartons after the cartons are converted from carton blanks. Such inserts have been used, for example, in detergent cartons to provide added strength for stacking and an internal moisture barrier and in beverage cartons to provide separators. However, installing inserts requires expensive specialized machinery, increases material and packaging costs, and can significantly slow the packaging process.
A problem with cartons in general, including micro-flute and paperboard cartons, is that they tend to tear and fail in areas of particularly high stress such as in certain corners of the cartons where folded panels meet. Such tears, once started, often can do spread, resulting in the separation of carton panels and ultimately in carton blow-out. Attempts to address this problem have included providing double folding flaps and/or tongues in carton blanks to reinforce the corners and, in some cases, gluing special corner reinforcements in cartons to inhibit tearing. Such attempts have not been completely successful.
In some situations, a product manufacturer may specify that cartons into which products are to packaged be printed on the inside in addition to the printing of logos and graphics on the outside of the carton. For example, a manufacturer may want to print contest rules, product instructions, special incentive coupons, or the like on the inside of product cartons. In the past, such interior printing has required that relatively expensive and time-consuming two-sided printing techniques be used to print both sides of a web from which the carton blanks are cut. Further, since interior surfaces of cartons generally are not coated for printing, the quality and character of printing available for interior carton surfaces has been limited.
A need therefore exists for an improved paperboard carton that provides the strength and rigidity of cartons made from micro-flute at a competitive cost. A related need exists for an efficient and cost effective method of making such paperboard cartons that uses traditional paperboard carton fabrication machinery and that does not substantially increase material costs associated with the fabrication process. Further needs exist for more efficient methods of providing paperboard carton inserts such as stiffeners and dividers and for providing higher quality printing visible on the interior surfaces of cartons where such printing is desired. It is to the provision of a method of making a paperboard carton and a resulting carton that addresses these and other needs and that overcomes the problems of the prior art that the present invention is primarily directed.
Briefly described, the present invention, in a preferred embodiment thereof, comprises a method of making reinforced paperboard cartons having enhanced strength and rigidity similar to that of micro-flute in selected regions where strength and rigidity are required. The method comprises the steps of advancing a web of paperboard along a path. The web of paperboard has a predetermined width according to the size of cartons to be made and preferably is drawn from a large roll of paperboard. The web of paperboard may or may not be pre-printed on the side that will become the outside of the finished carton with, for example, logos and graphics, according to application specific requirements. The web also may be printed on both sides if desired.
As the web of paperboard is advanced along the path, one or more ribbons of reinforcing material, each having a width less than the width of the paperboard web, is progressively applied to the web. Each ribbon preferably is applied with adhesive to the side of the web that will become the inside of the finished cartons and is positioned at a predetermined location across the width of the web. The location of each ribbon is selected to provide multiple layers or laminations of material in specific regions of finished cartons where enhanced strength and/or rigidity will be required such as, for example, in the side walls of the carton. Preferably, the ribbons of reinforcing material also are formed of paperboard and most preferably are pre-cut or slit to desired widths from paperboard trim or cull that otherwise may have reduced value. The ribbons are drawn from rolls that are pre-positioned to locate the ribbons properly on the web, advanced along and adjacent to the path of the web, supplied with adhesive on one side, and progressively brought into engagement with and compressed against the advancing paperboard web to adhere the ribbons to the web. In one embodiment, one or more of the ribbons may be pre-printed or on both sides with application specific indicia that ultimately will be exposed on the inside of finished cartons.
After the reinforcing ribbons are laminated to the advancing web, the web may be cut into sheets of a predetermined size. The sheets subsequently may be die-cut and scored with fold lines as required to form carton blanks defining the various panels and tabs that ultimately will become the walls of finished cartons. The carton blanks may be palletized and shipped to packagers, where the blanks are converted into cartons and packed with articles such as, for example, beverage containers or food items. When converted to cartons, the JD previously positioned and applied paperboard reinforcing ribbons form multiple layers or laminations of paperboard in selected portions of the cartons such as, for example, in their sides, where enhanced structural integrity is required. By appropriately selecting, sizing, and positioning the reinforcing ribbons, paperboard cartons having strength and rigidity comparable or superior to that provided by cartons made of micro-flute are obtained. Further, through judicious use of trim and cull in making the reinforcing ribbons, paperboard cartons made by the method of the present invention can be economically viable alternatives to cartons made of micro-flute.
In addition to providing paperboard cartons comparable in strength to micro-flute cartons, the present invention offers possibilities that are not obtainable with micro-flute. For example, the reinforcing ribbons of the present invention may be pre-printed on one side with high-quality graphics and indicia that is visible on the inside of finished cartons, all without requiring a two-sided printing process. Further, only a portion of one or more ribbons may be adhered to the paperboard web, with another portion being inwardly foldable to define interior carton structures such as stiffeners and dividers without the need for the insertion of a separate liner. Additional advantages are also provided, as will become more apparent below.
Thus, a unique reinforced paperboard carton and method of its manufacture is now provided that successfully addresses the problems and shortcomings of the prior art. The carton has structural integrity comparable to cartons previously made of micro-flute but is made of traditional paperboard material, which is easily converted to cartons in packaging machines with standard conversion machinery. The carton is economically competitive with cartons formed of micro-flute because of the unique use of trim and cull in forming the reinforcing ribbons and because the method of making the carton blanks can be practiced with existing paperboard fabrication machinery. The forgoing and other features, objects, and advantages of the invention will become more apparent upon review of the detailed description of the preferred embodiments set forth below when taken in conjunction with the accompanying drawing figures, which are briefly described as follows.
a through 6h are cross-sectional views of carton blanks made by the method of the invention illustrating some of the possible configurations in which ribbons of reinforcing material may be applied to a paperboard base sheet.
As mentioned above, carton blanks may be provided in the form of pre-glued knocked down sleeves or completely flat sheets depending upon the type of packaging operation in which they are to be used. The carton blank shown in
Referring now in more detail to the drawings, wherein like numerals refer, where appropriate, to like parts throughout the several views,
The fabrication line 11 in
Mandrels 18, three of which are illustrated in
As the web 17 and ribbons 21 are drawn from their respective rolls and advance along the path 15, the ribbons are positioned, according to the locations of their rolls 19 on mandrels 18, at predetermined locations across the width of the web 17. In the configuration illustrated in
The reinforcing material from which the ribbons 21 are formed may be any of a variety of appropriate materials such as, for example, thin plastic, fiberglass, woven or non-woven webs, or foam, and these and other materials are considered to be within the scope of the invention. Preferably, however, the ribbons also are made of paperboard and most preferably are cut or slit from paperboard trim or cull that otherwise has little or no commercial value. The invention will be described hereinafter in terms of ribbons of paperboard reinforcing material for ease and clarity of understanding. It should be understood, however, that the term “paperboard” when used in this context is intended to encompass and include any material with the physical and mechanical attributes necessary to provide the requisite reinforcing properties.
As the paperboard web 17 and ribbons 21 advance along the path 15, they move through a traditional de-curling station 22, where the paperboard of the web and ribbons is flattened and any curl that may have been induced by rolling the paperboard onto rolls 14 and 19 is removed. From the de-curling station 22, the web and ribbons advance further along the path 15 to a scoring station 24, which includes a pair of rollers 25 along which one or more scoring wheels 26 are disposed. The scoring wheels 26 are selectively positioned across the width of the rollers 25 to score the web 17 with longitudinally extending fold lines 27, along which carton blanks made by the method of the invention ultimately will be folded when converted into cartons.
As described in more detail below, some of the fold lines 27 may be located adjacent or along an edge of a reinforcing ribbon 21. In such cases, these fold lines preferably are carefully located a predetermined short distance from the edge of the ribbon so that the ribbon will not adversely affect or interfere with the folding of the paperboard along the fold lines. The scoring wheels 26 shown in
With the fold lines 27 scored in the paperboard web 17, the web 17 advances along the path 15 to a pair of guide rollers 31 and the paperboard reinforcing ribbons 21 diverge from the web 17 and advance to a gluing station 28 for receiving adhesive. In the illustrated embodiment, the gluing station 28 comprises an array of traditional adhesive applicators 29, each having a pair of nip rollers 32 between which one or more paperboard reinforcing ribbons pass. The lower nip roller 32 of each of the applicators 29 is partially immersed in an appropriate liquid adhesive contained within a flooded nip bath 33. As the paperboard reinforcing ribbons 21 pass between the nip rollers, a layer of adhesive is transferred from the lower nip roller of each pair to the bottom side (as seen in
Means other than nip rollers and nip baths for applying adhesive to the ribbons may be used to apply adhesive to the ribbons such alternative means include adhesive sprays, which commonly are used in the paperboard industry. Adhesive spraying mechanisms for use in the paperboard industry are commercially available and may be obtained, for example, from the Nordson Company. In any case, adhesive may be applied to the reinforcing ribbons 21 in a continuous coat, a discontinuous coat, a stitch-glued pattern, a strand, or otherwise. Preferably, the adhesive is applied in such a way as to minimize the amount of adhesive required to provide adequate paperboard to paperboard bonding. In one embodiment of the present invention, adhesive is applied along only one side of one or more of the ribbons to produce a finished carton having inwardly foldable internal structures such as separators and stiffeners, as described in more detail below.
The paperboard web 17 advances from the guide rollers to the compression station 34, which includes a pair main compression rollers 36, that also may function as pull rollers. Likewise, the adhesive bearing paperboard ribbons 21 advance from the gluing station 28 toward the compression station 34 and toward the paperboard web 17. At the compression station 34, the paperboard ribbons 21 and paperboard web 17 pass between the main compression rollers 36. The compression rollers 36 are set to compress the reinforcing ribbons 21 and the web 17 together with sufficient pressure to bond the adhesive and thus the ribbons to the web, or to other underlying ribbons in cases where multiple laminations of ribbons are to be applied to the web 17. In this way, the ribbons are progressively applied to the advancing web of paperboard at selected locations across the width of the web, as determined by the placement of rolls 19 on mandrels 18.
From the compression station 34, the paperboard web 17 with scored fold lines 27 and with the paperboard reinforcing ribbons 21 laminated thereto proceeds toward the downstream end 13 of the fabrication line 11 and toward a cutting station 37. In the illustrated embodiment, the cutting station 37 includes a traditional rotary knife assembly 38, which rotates to cut the web 17 across its width into rectangular sheets of a predetermined size. Each sheet has a width equal to the width of the paperboard web 17 and a length determined by the settings and operation of the rotary knife assembly 38. Means other than a rotary knife such as, for example, a traversing knife assembly or a platen cutter may be substituted for the rotary knife of the illustrated embodiment and these and other means for cutting the web should be considered equivalent to the illustrated rotary knife assembly.
Once the web 17 is cut into sheets 39, the sheets may be stacked and delivered to a die cutter, where the sheets are cut in a standard platen die-cutting operation to form carton blanks having the various tabs and panels necessary to form paperboard cartons embodying principles and features of the present invention.
As an alternative to cutting the web 17 into sheets 39 and subsequently die-cutting the sheets 39 to form paperboard blanks, the rotary knife assembly 33 in
When the blanks are converted, the ribbons of reinforcing paperboard laminated to the carton blanks form multiple layers of paperboard in selected portions of the cartons and thus reinforce the cartons in these portions. The locations of the ribbons are carefully determined in advance such that, when the carton blank is converted to a carton, the ribbons and thus reinforcement is provided in selected portions of the cartons such as, for example, in their side walls, where added strength and/or rigidity are required. Reinforced paperboard cartons made by the method of this invention have been found to exhibit strength and rigidity in the reinforced portions that is comparable or superior to that of cartons made from micro-flute.
With the forgoing specific example in mind, it will be appreciated that, in one embodiment, the present invention is a unique method of making reinforced paperboard cartons. The method includes the steps of advancing a web of paperboard along a path, the web of paperboard having a width. At least one ribbon of reinforcing material having a width less than the width of the paperboard web is progressively applied, preferably with adhesive, to the advancing web at a predetermined position across its width. The web with its applied reinforcing ribbon is cut to form carton blanks and the carton blanks are formed into cartons for receiving articles, the ribbon of reinforcing material providing reinforcement in selected portions of the cartons where added strength is required.
Paperboard reinforcing ribbons 62 are laminated to the base sheet 55 according to the method of the invention. The reinforcing ribbons 52 are positioned along and increase the effective thickness of the end tabs 61 to reinforce the end tabs and provide enhanced structural integrity in the end portions of a carton converted from the blank. During conversion of the blank 51 into a carton, the various panels and tabs of the blank are folded generally inwardly along the scored fold lines 52 and 53 as indicated by arrows 60, and selected ones of the tabs are secured together with adhesive or otherwise to form a rectangular carton to be packaged with articles. The carton, when formed, has ends defined by the end tabs 61 that are reinforced by the paperboard reinforcing ribbons 62 laminated thereto to provided enhanced strength, rigidity, and tear or blow-out resistance in the ends of the carton. Thus, when the blank 51 is converted, it forms a reinforced paperboard carton having a plurality of panels defining sides and ends of the carton an a layer of reinforcing paperboard material applied to selected ones of the panels to reinforce the carton in selected regions defined by the reinforced panels.
It has been found that a distance between a fold line and an edge of a reinforcing ribbon of about 0.030 inches, which is an industry standard paperboard thickness, allows unimpeded folding of a carton blank along the fold line while having little or no effect on the structural reinforcement provided by the reinforcing ribbon. It also has been found that a distance of about 0.030 inches is easily achieved and maintained when performing the method of this invention with standard paperboard making machinery as illustrated in
a through 6h are provided to illustrate some of the many possible configurations in which reinforcing ribbons may be applied to a paperboard web using the method of the present invention. Each of these figures is a cross-sectional view of a web with reinforcing ribbons applied thereto and longitudinally extending fold lines are scored in some of the figures. It should be understood that these figures do not necessarily represent configurations corresponding to actual carton blanks, but instead are generally simplified drawings selected for clarity in describing some of the many possible configurations of reinforcing ribbons. Also in this regard, the thickness of the paperboard web and reinforcing ribbons generally is exaggerated in
In
b illustrates a possible configuration similar to that of
c illustrates the possibility of applying multiple laminations of reinforcing ribbons, one atop the other, to provide even more reinforcement in areas where further enhanced structural integrity may be required. In this figure, three stacked reinforcing ribbons 78 are applied along the opposed edge portions of a base sheet 76, to form multiply laminated reinforcing strips 77. Such a configuration may be formed by the method illustrated in
d illustrates the ability to apply multiple reinforcing ribbons at selected locations across the width of a paperboard web using the method of the invention. Here, three reinforcing ribbons 81 are applied to a paperboard base sheet 82, two along the opposed edge portions of the base sheet and one intermediate the edge portions. While the reinforcing ribbons 81 in
e illustrates the possibility of applying selectively positioned multi-layer reinforcing ribbons to a paperboard base sheet. Multiple layers of reinforcing ribbons 84 are applied atop each other on a base sheet 82 to form reinforcing strips 83, one extending along each of the opposed edge portions of the base sheet and one positioned intermediate the edge portions. Of course, any number of strips 83 may be applied, each of the ribbons 84 and resulting strips 83 may be any desired width, and the strips may be applied at any desired location across the width of the base sheet 82.
f shows the possibility of applying multiple reinforcing strips formed of multi-layer reinforcing ribbons at selected positions intermediate the edge portions of a base sheet. Multiple reinforcing strips 87 each formed of multiple layers of reinforcing ribbons 88 are applied to the base sheet at selected locations on the base sheet 86 not extending along the edge portions thereof.
g illustrates a configuration possible with the method of the invention wherein one or more reinforcing strips 91 applied to a base sheet 89 is formed of multiple layers of reinforcing ribbons 92 and 93 the reinforcing ribbon 93 having a width less than the width of reinforcing ribbon 92. Any number of layers of ribbons may be applied in this manner to form multi-layer reinforcing strips with each ribbon of the strips having a width different from the widths of the other ribbons of the strips, according to application specific requirements. A relatively narrower reinforcing ribbon 94 is applied in
h illustrates a unique application of the method of this invention to form internal structures of a carton such as, for example, L-brackets, stiffeners, and separators. A ribbon 97 is applied to a base sheet 96 according to the method of the invention. In this case, however, the method includes applying adhesive along only one side of the ribbon before bonding the ribbon to the paperboard web. The ribbon 97 has a fold line 101 scored therein and the fold line separates the ribbon into a first section 98 and a second section 99. Adhesive is applied to the first section 98, which is bonded to the base sheet 96, and the second section 99 is free to be folded along fold line 101 as indicated by arrow 102 to project in a direction away from the base sheet 96.
The fold line 101 in the ribbon 97 may be scored at the scoring station 24 (
Further according to the invention, the reinforcing ribbon 109 on the back wall 107 of the carton 106 is seen to have been pre-printed with indicia that is visible on the inside of the carton. Thus, the method of this invention may eliminate the requirement of double sided printing on a carton base sheet when it is desired to display indicia on the inside of a carton. In
In addition or as an alternative to the printing of indicia, reinforcing ribbons may be pre-coated if desired with a moisture resistant or other type of coating. In such cases, the method of this invention may be used to make efficiently produced lined cartons for use as alternatives to cartons such a detergent boxes, which traditionally have been supplied with separate individually inserted liners.
Paperboard dividers and stiffeners 126 are applied as described above relative to
The invention has been described herein in terms of preferred embodiments and methodologies, which represent the best mode known to the inventors of carrying out the invention. It will be understood by those of skill in the art, however, that many additions, deletions, modifications, and substitutions of equivalent elements not specifically included in the preferred embodiments may be made without departing from the spirit and scope of the invention as set forth in the claims.
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