US2628179A

US2628179A - Method of producing cartons having metal tearing edges

Info

Publication number: US2628179A
Authority: US
Inventors: Robert M Bergstein
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-02-01
Filing date: 1950-02-01
Publication date: 1953-02-10
Anticipated expiration: 1970-02-10

Description

Feb. 10, 1953 R. M. BERGSTEIN METHOD OF' PRODUCING CARTONS HAVING METAL TEARING EDGES Filed Feb. 1, 1950 2 SHEETS--SHEET l FIlLZ;

IN VEN TOR.

ATTORNEYS.

Feb. l0, 1953 R, M. BERGSTEIN 2,628,179

METHOD OF PRODUCING CARTONS HAVING METAL TEARING EDGES Filed Feb. l, 1950 2 SHEETS- SHEET 2 Patented Feb. i0, 1953 METHGD OF PRODUCING CARTONS HAVING l METAL TEARING EDGES Robert M. Bergstein, Wyoming, Ohio Application February 1, 1950, Serial No. 141,697V

14 Claims. (Cl. 154-118) My invention has to do with the provision ci paperboard boxes or other structures having an edge portion against which a iiexible material may be torn. Boxes of this type are commonly used to contain rolls ci flexible material such, for example, as waxed. paper, the material being Withdrawn from the carton and torn from the roll in such length as may be required for a particular use. Y

The primary objects of my invention are tw fold: the provision of boxes or other structures having tear strips at a lesser cost than has hitherto been found necessary in the practical art, and the provision of specific improvements in boxes or other structures provided with tear strips; all as Will hereinafter be set forth.

These and the more specific objects of my invention, which will be apparent to the skilled worker in the art upon reading these specifications or will be later pointed out, I accomplish by that procedure and in those structures of which I shallnow describe certain exemplary embodiments with reference to the drawings which form a part hereof, and in which:

Figure 1 is a plan View of a blank for one form of box produced in accordance with my invention.

Figure 2 is a partial sectional view of the tear strip portion and adjacent body Wall taken along the section line 2 2 of Figure 1.

Figure 3 is a transverse cross-sectional view of an erected box formed from the blank of Figure l and containing a roll of dispensable material.

Figure e is a plan View of a box insert designed to be employed with a paperboard carton of otherwise conventional construction..

Figure 5 is a transverse cross-sectional view of a paperboard carton fitted With theinsert of Figure 4 and containing a roll of dispensable material Figure 6 is a plan view of vanother typeof ineert. p

Figure 7 is a longitudinal section through the erected insert as positioned in a carton, the carton and the roll of dispensable material-'being indicated in dot-dash lines. Y

Figure 8 is a transverse cross-sectional view of a carton having a type of doubletear strip .hereinafter described. y

Figure 9 is a vertical longitudinal section diagrammatic in nature of an apparatus suitable for associating tear strip material with paperboard for the formation either of cartons or of inserts. The section responds to section line .9-9ofFigure10- Y I -1` 1 sii) Figure 10 is a partial horizontal section related to the section line IU-I of Figure 9 and showing most of the apparatus elements of that figure in plan.

Figure l1 is a plan view of a double blank illustrating a preferred mode of manufacture of the blank element of Figure i.

Figure 12 is a longitudinal vertical section. partially diagrammatic in nature, of a series of machine elements especially adapted for the formation of box inserts.

Figure 13 is a plan vievs1 corresponding to Figure l2.

Figure 14 is a plan View of one form of blank from which the structure illustrated in Figure 8 can be made.

Figure 15 is a plan view cf a blank of the general type of that of Figure 1 but modified as to the nature of the tear strip.

I-litherto in the manufacture of boxes having tear strips, it has been the substantially universal -practice to form tear strips from metallic members and then attach these metallic members to the edges of a Wall of a ,carton blank. The operation is expensive and time-consuming, requiring the use of special machinery not only for the attachment of the tear strips but also for their initial formation. The tear strips either present a straight, sharp edge for tearing purposes or a series of serrations or teeth. In either event these are located beyond the actual edge of the paperboard of the Wall of the box to which they are attached; and present some danger of injuring the hands of the user. I have found that excellent tear strips may be made by methods hereinafter described in detail by involving essentially the adhesive attachment of a metal strip element to paperboard and the simultaneous severing ofthe two layers to form the actual tearing edge. Very considerable economies are effected in my procedure in several ways. The operation of attaching a metal strip is simple end inexpensive, involving only the rolling on of a preformed metallic strip with the interposition of a suitable adhesive, the strip being withdrawn from a continuous 'supply such as a roll which may be formed by slitting a Wide supply. `There are no forming operations performed upon the metal as such and the'entire cost of such operations is saved. Since the paperboard and the metallic strip'. are concurrently severed or cut, the'edge of the strip will be backed by paperboard adhesively secured to it at its outer or tearing edge. This not only makes the structure safer to use sincefthe. likelihood of scratches and cuts is less, but since the paperboard reinforces the actual cutting edge whether toothed or straight, I am enabled to use thinner gauges of sheet metal in the formation of adequate tearing strips. Many commercial tear strips hitherto produced must be wider than mine due to the exigencies of their attachment, and this amounts to a further saving in metal. It is a feature ci my invention that when a composite of metal and paperboard is cut or slit in accordance with my invention, two tear strips are concurrently formed which, again, represents a substantial economy in cost. The principles of my invention also lead to the possibility of the manufacture of tear strip structures especially those designed to serve as inserts in standard paperboard cartons, by the use of fully automatic mechanism which is extremely simple and inexpensive, as will hereinafter be explained in detail.

The nature of the metal andv its thickness do not form necessary limitations on my invention. As indicated, however, thev actual tearing edge provided by my tear strips is reinforced by paperboard in adhesive union with it and thisr enables me to employ thinner metal than would be effective otherwise. In the practice of my invention, I have found that excellent results may be obtained through the use of metal as thin as that having a thickness of from .003 to .005 in. whereas the commercially produced formed metal tear strips which are attached as above indicated to cartons, regularly have a thickness of from .008 to .010 in. Heavier and lighter materials than those indicated above may also be used in the practice of my invention; and it will be understood that it is within the scopev of my invention to apportion the thickness of the metal used to the thinness and tear resistance of the dispensable product to be torn on the edge. Various metals may be employed including relatively soft and non-springy metals such as aluminum and non-hardened copper; but I have found that excellent results may be attained through the use of light, cold-rolled iron or mild steel especially when employing such a material in its work-hardened condition,

Adhering the metal to the paperboard merely involves the use of an adhesive which will form a good and permanent bond with each. There are many adhesives which will serve. I prefer adhesives which do not set up to a hard and brittle condition but rather maintain a degree of elasticity in the hardened condition together with a strong cohesiveness. Many commercially available adhesives will serve my purpose, including animal and vegetable glues, such substances as bitumen, and the like. I have attained excellent results both with thermoplastic adhesives and with those which are water emulsions or dispersions of rubbery and resinous substances. Examples of commercially available adhesives which are excellent for my purposes are: A natural rubber latex base adhesive such as the product sold under the name Wond-R- Glu by the American World Chemical Company of St. Louis, Missouri, or an adhesive dispersion, understood to have a synthetic rubber base sold under the name NI-413 by Union Paste Company of Hyde Park, Massachusetts.

As indicated, in the practice of my invention the metal strip is adhesively united to paperboard and the two are then concurrently severed tc form a cutting edge. Severing may be done by dies operating in a press, by continuous slitting with straight or serrated cutters, or by the operation of cutting and scoring presses such as are employed for the manufacture of cartons. In the light of this, it will be apparent that in one procedure I may attach metal strips to a supply of paperboard or boxboard designed for the formation of cartons, and then form cartons from such a supply by ordinary cutting and scoring including the cutting of the previously applied metal strip or strips, all cutting and scoring being done at the same time. The paperboard may be printed either before or after the attachment of the strip or strips.

Yet again, I may form carton blanks complete, then attach my metal strips to the blanks and afterward cut concurrently the paperboard and the metal. In this connection, since the cutting of the composite of paperboard and metal can be employed' to form two tear strips, it is advantageous to form the cartons in multiple with corresponding edges joined and unsevered. The metal strip may then be applied over the joined and unsevered edges, after which the operation by which the composite of metal and paperboard is cut or slit will serve to separate the different carton blanks from each other.

Yet again, I may adapt the teachings ofmy invention to the formation of inserts for cartons which otherwise can be of fully conventional form; and in doing this I may form the inserts both in multiple. and continuously.

In cutting the composite of paperboard and metal,A I prefer to cause the knife or die to pass through from the paperboard side. This results in a slight displacement of the cut edge of the metal strip away from the paperboard side of the composite, thus providing a sharper cutting edge or in the case of serrations or teeth, a displacement of the ends of the teeth toward the metal side resultingV in their better exposure to the material to be torn. By reason of the con tinuous adhesive union of the metal and the paperboard, the teeth remain reinforced throughout their extent andthe paperboard follows the displacement of the cutting edge or teeth so as to remain as a continuous reinforcement. Since the tear strip will normally be located at the inside surface of a box or carton, the displacement of the teeth inwardly not only makes the tearing action more eiicient, but makes the tear strip as such less likely to present sharp or jagged edges at the outside of the structure.

The cutting may be done by ordinary cutting rules in a die such as is used for cutting paperboard in the manufacture of cartons. Again, I may employ continuous cutters, for example those in which a rotary knife element having either a straight or a serrated cutting edge, operates against an anvil roll or else against the conforming edge of another rotary element, exerting with the first a shearing action. With the use of relatively thin metal, cutting rules such as areused for paperboard will last a fairly long timefalthough if the run is long, it may be necessary Ato renew those cutting rules which cut metal before other cutting and scoring rules require rcnewal. It is comparatively easy to cut through the metal and paperboard composite from the metal side; but if as I prefer, the cutting is done from the paperboard side, this may be found more difficult with such cutting and scoring dies as are commonly used in the making of paperboard cartons. Indeed, where the metal is relatively heavy and a plurality of cuts is to be made at the same time, it may be found that the ordinary cylinder type of cutting and scoring press will not serve. The cutting and scoring, however, or at least that part of it which involves the cutting of metal strips, may be performed in a moving platen type of platen press, such as the so-called Thompson press where greater cutting pressure may be employed.

It is quite possible, I have found, to form an adequate toothed cutting edge by cutting through the composite oi' paperboard and metal with the familiar nicked cutting rule frequently used for forming a line of weakening in boxboard. This, of course, does not result in complete severance of the metal and the boxboard along the line of cut; but the two partially severed parts are readily thereafter separated by bending one or more times until the small connecting portions of the metal break. This results in a series of smallr sharp, jagged teeth productive of an excellent tearing edge, but there is involved the expense of the manipulations of bending, usually performed by hand, to separate the parts. For this reason, I prefer an operation in which the parts can be severed completely in the cutting operation.

Referring now to Figure 1, l have there illustrated an exemplary form of box formed of paperboard cut and scored to provide a front wall i, a bottom wall 2, a rear wall 3, a top l and a top tuck flap 5 articulated together by the usual score lines in the order named. The front, bottom and back walls are provided with end closure flaps 6, "l, S, s, Iii and H which may be of any form desired and may have interlocks, although a sealend form of structure which can be set up about a mandrel is generally preferred. The closure flaps l and i l on the ends of the back wall are provided with top flaps l2 and I3 coacting with the top wall 4 in forming a top wall closure. The line of articulation between the top wall 4 and the tuck flap 5 may be provided with notches It and l5 interlocking with edge portions of the flaps I2 and I3 to hold the box closed. Such a construction is conventional and well known in the art.

My structure .has adhesively secured to the free edge of the front wall l a metal strip I6 having a cut edge for tearing. The edge may be straight as shown at il in Figure or it may be slotted and provided with teeth IS as shown in Figure 1.

A cross-section of the edge presenting the tear strip is shown in Figure 2. Where the composite of paperboard and metal has been cut in the way set forth above as preferred, the metal and paperboard are slightly displaced to the metal side, as indicated at i9 in Figure 2, giving either a sharp tooth or a sharp cutting edge as they case may be.

Figure 3 is a transverse cross-sectional view showing the use of the erected structure with a roll 2s of disposable material such, for example, as wax paper. Like parts have been given like index numerals in Figure 3 and are readily identifiable. It will be noted that the disposable material issues and is withdrawn from the package between the tuck flap 5 and the edge of the front wall l which provides the tear strip. The displacement of the teeth or cutting edge inwardly, as illustrated at I@ in Figure 2, helps to retain the edge of disposable material from the roll 2d with a portion thereof torn olf, and tends to prevent the loss of the free edge inside the box. It will be understood that ordinarily when a length of material is withdrawn from the box and torn off, the tearing proceeds on a line extending slightly aslant to the true transverse axis of the length of material so that one edge portion tends to protrude from the box. The inwardly directed teeth or cutting edge tend to retain the protruding material.

Considering the manufacture of such a structure as is illustrated in Figure 1, I may, as shown in Figures 9 and 10, provide sheets 2| of boxboard of a size suitable for printing, cutting and scoring in the formation of cartons. These sheets may be caused to move along a. table 22 by pins 23 on a. pair of conveyor chains or belts 24, 25 mounted on suitable sheaves and driven as desired. As indicated in Figure 10, side guides 2B 2l may be provided. As the sheets move along, one or more metallic strips 28 from a roll or rolls 29 are coated with adhesive as by a conventional coater 3f! and are pressed by one or more pressure rolls 3l into contact with the sheets 2 l. It will be understood that the strips 28 are applied along those predetermined lines in the sheets 2! where severance of the strip or strips in the ways hereinabove described will result in the formation of tearing edges at the desired position of the carton blanks.

As the treated sheets are fed forwardly beyond the end of the conveyors 24, 25, as by pinch rolls 32, the interconnecting portions of the metallic strip or strips 23 may 'ce severed, as by a fly knife 33 and stacked by feeding rolls 34 in a stack 35. ri'he sheets so treated may then be treated in cutting and scoring presses for the formation of cartons therefrom. Preferably the sheets will have been printed as desired before being treated as in Figures .9 and 10; but since it is possible to print the sheets after the metallic strips have been adhered to them, the skilled worker-n the art will understand from the description above that it readily possible to apply one or more metallic strips to a continuous supply of paperboard, afterwards severing both the paperboard and the strip or strips .into individual sheets which may be stacked, as at 35. Again, the continuous supply may be imprinted or printed, but in the latter event, the fly knife 33 will have to be so timed with respect to the printed representations on the supply as to form sheets suitable for cutting and scoring.

Yet again, the elements 2i in Figures 9 and 10 may be in the form of multiple carton blanks rather than unscored sheets. Such a multiple carton blank is illustrated in Figure 11 and consists of at least two blanks A and B, so formed that the top edges of their front walls are juxtaposed and joined. It is over this juncture that the metallic strip 28 is applied as aforesaid. Afterward, the metallic strip is slit or out along its median line which has the combined result of forming the cutting edge as hereinabove explained, and also of severing of the multiple carton blanks from each other. In this event the cutting of the composite of metal strip and paperboard can be accomplished on the same cutting and scoring press by which the multiple carton structures were formed, or it can be done on other mechanism. The cutting may, for example, be accomplished on apparatus such as that shown in Figure 9 with a continuous cutting element 35 operating against an anvil roll 3? as indicated in dotted lines in that figure.

The principles of my invention are also adapted to the formation of cutting strip inserts to be inside cartons of conventional construction. One form of insert is illustrated in Figure 4 as consisting of a paperboard body presenting a front wall la, a bottom wall 2a and a back wall 3a, the front wall being provided with a tear strip 55a. in the formation of such lastructure I may employ mechanism such as is shown in Figures 12 and 13. Here a continuous supply 38 of boxboard is withdrawn from a roll 39. As it passes between pinch rolls 40, a strip 28a which has previously been coatedV with adhesive is pressed to its surface. A rotary cutter il having a cooperating element 42 on the opposite side of the supply may be employed to slit the supply midway of the metal strip 28a. As indicated above, the continuous cutter may be of the shearing type, but is preferably of the blade and anvil roll type. The blade 4| may be straight or serrated, For demarking and articulating the portions la, 2a and 3a from each other, I may employ continuous scoring devices :i3` operating against an anvil roll or rolls 4d. Additional pairs of pinch rolls 45 and 45 may be used to propel the product which then is severed into the required lengths by the fly knife 47 and stacked as at 48.

The Inode of use of inserts of this type is illustrated in Figure 5. It will be evident from this figure that the inserts are erected or formed into U-shape and placed in the erected carton prior to the insertion of the roll 20 of dispensa-ble material. The mode of formation of the inserts is cheap and continuous. They may if desired be formed of paperboard substantially heavier than that employed for the carton itself, thus reinforcing the carton, providing a stiffer pack-- age, and if desired permitting the use of thinner boxboard for the carton itself.

Another form oi?V insert is illustrated in Fig urev 6 as comprising a paperboard body having a front wall element lb, to the ends of which end elements i9 and 58 are articulated as shown. The mode of use of this type of insert is illus* trated in Figure '7 and does not require extended description. Again, the insert is erected by bending the end elements 49 and 5G at right anglesto the front panel ib; and the structure is inserted in the carton as before. The engagement of the top portion or lid of the carton with the

end elements

49 and 56 will serve to retain the insert in place, Inserts such as those shown in Figure 6 may be formed in the same continuous fashion as has been described above in connection with Figures 12 and 13 and on the same apparatus, with the substitution of a transverse scoring device well known in the art for the longitudinal scoring devices t3, dii.

When boxes are provided with tear strips, it is well understood that the tearing should be done by drawing the material toward, not away from, the tear strip. Nevertheless, the housewife in haste frequently attempts to tear the material in the wrong direction, in which case the tear strip can perform no function. 'Fearing the material in the wrong direction may also be occasioned by the manner in which the box is picked up from a shelf or support and in which hand. In the practice of my invention it is readily possible to'provide a box having a tear strip formed on each of the two meeting edges of a pair of adjacent body walls so that irrespective of the direction in which the user attempts to tear the dispensable material, there will always be presented a tear strip in the right position. A mode and structure for accomplishing this is illustrated in Figures 8 to 14, the latter showing a blank having a rear wall I, a top wall 52, a rear wall 53, a bottom wall 54 and an element 55 which is either a tuck flap or a glue flap, preferably the latter. End closure elements 56,

51. 56 and 59. 6D, 6i are articulated respectively to the ends of the body walls 5l and 52 and 53: and the adjacent closure elements, i. e. 55, 57. 58 at the left-hand end of the body walls and 5E), 60, 6 IA at the right-hand end ofthe body walls are articulated to each other by prolongations of the score lines between the body walls. The closure elements 55. 58, 59 and 5i are provided with diagonal score lines as shown. The body wall 54 is provided with end closure flaps 62 and 63. In forming this carton the metallic strip 64, which is to provide the dual tear strips, is adhesively affixed to the boxboard over the line of demarkation between

walls

52 and 53. It is slit along its median line as at 65, but the slit terminates at the ends of the

body walls

52 and 53. Such a structure may be used as a tuck flap carton, but it is more conveniently tubed by folding along the lines of articulation between body walls 5| and 52 and

body walls

53 and 54 with the adhesive union of the flap 55 to the free marginal portion of the body wall 5l. It may be shipped to the packager in this condition. The packager will then erect the tubular body, close one end of it, insert the roll of dispensable material through the opposite end and then close that end. In the particular form of carton illustrated, in forming an end closure, the closure portions provided with the diagonal score lines, such as 5S and 58, will fold bellowswise with the bellows folded portions disposed beneath the element 5l. The closure may be completed either by adhesively securing the flap 52 to the outer surface of the element 5l, or by inserting the flap 62 beneath the element 5l wherel it will engage between the element 57 and the bellows folds, making a secure closure.

One object of providing end closure elements, articulated to each other is to make it possible to slit the metallic strip d for the entire length of the body walls, so that the carton need not be substantially longer than the roll of dispensable material which it is to contain. However, if the carton is made somewhat longer than the roll, it will then be possible to slit the strip 64 for less than the full length of the body walls. in which event closure elements, all o which are free of each other, may be employed.

In either event a structure is provided for use as illustrated in the cross-sectional View, Figure 8, in which along the line of emergence of the dispensable sheet material 65, there is a tear strip 5'! or 58 on either side of it. Thus, no matter in which direction the user attempts to tear o' the dispensable material, a cutting or tearing edge will be presented for the purpose, and it will be quite impossible to tear the substance ofi in the wrong direction.

It may be pointed out that in the blank of Figure 14 the unsevered portion of the metallic strip 6d, overlying as it does certain lines of fold in the paperboard, tends to maintain the folded condition of the paperboard in the erected structure which is of Value in maintaining the closure.

Modifications may be made in my invention without departing from the spirit of it. Having thus described my invention, what I claim az; new and desire to secure by Letters Patent is:

l. A :process of providing a paperboard article lia-ving a reinforced tearing edge which comprises providing a paperboard member and a relatively narrow strip of thin metal, adhesively securing the narrow metal strip to said paperboard member, concurrently severing the paperboard and metal by forming a cut therein extending longitudinally of the metal strip, whereby to provide at least one metal tearing edge supported and reinforced bv a lpaperboard member.

2. The process claimed in claim 1 in which the cutting is done by passing a severing element through the combination from the paperboard side whereby slightly to deflect the paperboard and metal immediately adjacent their cut edges.

3. The process claimed in claim l wherein the paperboard element is a cut and scored element having articulated parts.

4. The process claimed in claim 1 wherein the paperboard element is a cut and scored elemenll having articulated parts, and wherein the scoring of the said vpaperboard body is performed concurrently with the severing of the metal and paperboard. combination.

5. rhe process claimed in claim 1 wherein the paperboard element is a cut and scored element having articulated parts, and in which the paperboard. extends on both sides of the metal strip and is cut and scored, the severing of the combination of metal strip and paperboard serving to divide the composite into two useful articles, each having a tearing edge.

6. The process of claim 5 in which the useful articles are each paperboard cartons.

7. A process of making carton inserts with tea-ring edges which comprises the steps of moving a continuous supply of paperboard, continuously adhering a narrower metal strip to the paperboard intermediate its edges, scoring the paperboard and slitting the metal strip and paperboard concurrently along a line intermediate the edges of the metal strip, the last two mentioned step-s :being performed in indifferent order, and then severing the treated material into individual pieces by cutting it transversely.

8. A process of making articulated paperboard articles with tearing edges which comprises adhering a relatively narrow metal strip to relatively wider paperboard material and thereafter forming at least one articulated structure from the composite by cutting and scoring including forming a cut conjointly through the metal strip and the paperboard to provide a tearing edge.

9. The process claimed in claim 8 wherein the articulated structure so formed is a paperboard carton.

l0. The process claimed in claim 8 wherein the articulated structure so formed is a paperboard carton, said last mentioned cut being formed along a line of articulation between body walls of said carton.

l1. The process claimed in claim 8 wherein the articulated structure so formed is a paperboard carton, said last mentioned cut being formed. along a line of articulation between body walls of said carton, said carton having body walls in articulation and closure elements articulated to the ends of said body walls, adjacent closure elements being joined in a prolongation of the said line of cut, the metal strip being unsevered along the line of said joining.

12. The process claimed in claim 8 wherein at least two articulated structures are formed concurrently, the cutting of said metal and said paperboard concurrently serving to sever said articles from each other.

13. A process of producing cartons having metal tearing edges which comprises moving sheets of paperboard in a path, adhering a narrower metal strip to said paperboard sheets continuously, severing said sheets from each other, and afterward cutting and scoring said sheets to form carton blanks, including the step of forming a cut through the metal strip and paperboard concurrently, said cut extending longitudinally of the metal strip and acting to form the tearing edge of each carton.

14.The process claimed in claim 13 wherein the last mentioned cut is produced by passing a cutting element through the composite from the paper side.

ROBERT M. BERGSTEIN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,023,527 Smith Apr. 16, 1912 1,499,808 Distin July 1, 1924 2,069,335 Salsberg Feb. 2, 1937 2,115,853 Hill May 3, 1938 2,235,623 Ross Mar. 18, 1941 2,237,346 Gilfillon Apr. 8, 194.1. 2,284,724 Church June 2, 1942 2,306,178 Meany Dec. 22, 1942 2,316,469 Thor Apr. 13, 1943 2,323,105 Welch June 29, 1943 2,336,842 Broeren et al Dec. 14, 1943 2,425,043 Moore Aug. 5, 1947 2,437,022 Fritizinger Mar. 2, 1948 2,555,944 Bergstein Aug. 28, 1951 2,566,249 Rainey et al Aug. 28, 1951

Claims

1. A PROCESS OF PROVIDING A PAPERBOARD ARTICLE HAVING A REINFORCED TEARING EDGE WHICH COMPRISES PROVIDING A PAPERBOARD MEMBER AND A RELATIVELY NARROW STRIP OF THIN METAL, ADHESIVELY SECURING THE NARROW METAL STRIP TO SAID PAPERBOARD MEMBER, CONCURRENTLY SEVERING THE PAPERBOARD AND METAL BY FORMING A CUT THEREIN EXTENDING LONGI-