BOOK OR BOOKLET, BOOK OR BOOKLET COVER OR FOLDER AND METHOD OF MAKING THE BOOK COVER OR BOOKLET COVER OR FOLDER

Description

[0001] This invention relates to a book or booklet including a leafblock and a cover part comprising at least a front cover and a back cover and possibly a back and formed of sheet or web material which is board, cardboard, paper or the like by folding and bringing the material layers fitted against each other to adhere to one another, whereby the cover part is formed by folding a one- or multi-layer sheet or web material blank in one piece against itself at all free edges of the front cover and back cover and by making the at least two material layers folded against each other to adhere to each other by means of adhesive material. The invention also relates to a book or book cover or a folder comprising at least a front cover and a back cover and possibly a back and formed of sheet or web material which is board, cardboard, paper or the like by folding and bringing the material layers fitted against each other to adhere to one another, whereby the cover or folder is formed by folding a one- or multi-layer sheet or web material blank in one piece against itself at all free edges of the front cover and back cover of the cover or folder and by making the at least two material layers folded against each other adhere to each other by means of adhesive material. In addition, the invention relates to a method of making a book or booklet cover or a folder of sheet or web material which is board, cardboard, paper or the like by folding and making the material layers fitted against each other adhere to each other, whereby a one- or multi-layer sheet or web material blank in one piece is folded at all free edges of the front cover and back cover of the cover or folder against itself and the at least two material layers folded against each other are made to adhere to each other by means adhesive material.

[0002] Traditionally, books are divided into two groups, hard-bound or hard-covered and paperbacks, respectively, according to how they are bound.

[0003] The front cover and back cover of hard-covered books are formed with a rigid core of cardboard which is lined both inside and outside. Outside lining is done by folding the edges of the lining material around the edges of the cardboard core and by glueing together the lining material and the cardboard core. The inner lining again is glued onto the cardboard core to lie on the edges of the outer lining. Inside lining is done only in a further process, that is, at a casing-in stage when combining the leaf part and the cover of the book. The books hve been bound so that the back part of the book contains a sleeve or other structure between the cover and the leafblock or bookblock formed by leaves bound together, to keep the back part of the cover off the back part of the book's leaf part. The cover edges thus produced are very wear-resistant. However, binding requires many different work steps.

[0004] Paperbacks again are bound by glueing together the book leaves at their back part to form a bookblock or block and by glueing together the bookblock and the back of a cover part made of board. An improvement on this earlier paperback is described in Patent Publication EP-A-0077795. In this improved method, a sleeve is used in the back or spine of the book which when flattened is slightly wider than the back. An open fold is thus left on both sides of the back allowing the book to be opened so that it also remains open and the back part of the cover will not tend to break. A problem with paperbacks has been the tendency of cut board edge surfaces at the cover edges to fray and crack up. Two other examples of the prior art are published in DE-A-2420926 and in US-A-4615541.

[0005] The object of the present invention is to achieve a method of making books as advantageously as paperbacks but wear-resistant like hard-covered books. With this invention the product's degree of processing can be raised to a level replacing the production of hard covers.

[0006] A book or booklet and the cover or folder as well as the method in accordance with the invention are defined in the independent claims 1, 4 and 7.

[0007] The method in accordance with the invention can be applied with conventional machines of the packaging industry used for manufacturing casings used to package various consumption articles. These machines can be used for folding and glueing book covers in accordance with the invention. Finished covers can then be delivered for binding into a leafblock, the leaves of which have been printed and bound into a bookblock at the printing house. In this way, the book is made at considerably more advantageous costs than when using traditional methods.

[0008] Covers in accordance with the invention which have properties of hard covers can be made by using a cover blank in one piece and there need not be any separate stiffening core part in the cover. Sufficient rigidity is obtained by means of edge folds and by glueing two folded layers of the cover blank against each other. Folding of the edges also results in durable edge surfaces which do not break or crack up easily. A product comparable to a hard-covered book can be made by using a book-making process intended for paperbacks. The result is a cover with high wear resistance. There are several suitable applications for a cover in accordance with the invention, for example, text books, manuals, telephone directories etc. A cover in accordance with the invention can also be made for conventional production processes specialized in hard cover production. Traditional cost burdens relating to cover production are hereby avoided.

[0009] The invention and its details are described more closely in the following, referring to the enclosed drawings, wherein

Figure 1 shows manufacturing elements for previously known hard covers,

Figures 2a and 2b show a known type of a book cover blank and of a finished cover

Figures 3a and 3b show a a known variation of the book cover blank and finished cover of the Figures 2a and 2b, in which a sleeve is used,

Figures 4a and 4b show a another known variation of the book cover blank and finished cover of the Figures 2a and 2b,

Figures 5a and 5b show a further variation of the book cover blank and finished cover of the Figures 4a and 4b, in which a sleeve is used,

Figures 6a and 6b show a further variation of the book cover blank and finished cover of the in which the edges of folded parts are chamfered,

Figures 7a and 7b show a further application where the inner layer of the cover part is obtained by means of one fold part,

Figures 8a and 8b show an application in which the corners of the book cover are rounded off, and

Figure 9 shows a material blank to form a book cover or a folder according to the invention.

[0010] As is shown in Figure 1, a previously known hard book cover is formed of a cardboard core 1 of the front and back cover, of a back 2 and of a covering material or lining 3. The cardboard used may be, for example, about 2 mm thick grey so-called woodpulp board. The back board is usually of a thickness less than 50 % of the cover cardboard thickness. The lining material used can be paper, cloth, plastic and their combinations and mixtures. The lining material sheet 3 to be glued onto the outer cover surface is of such a large size that the lining can be folded over the free edges of the cardboard core. The cut cardboard edge surface is thus hidden. An inner lining (not shown in the drawings) is glued onto the inner cover surface. The inner lining is done at the casing-in stage when combining the leafblock and the cover. The book's so-called flyleaf is hereby glued at its outer side to the inner cover surface and it forms a lining for the inner cardboard surface.

[0011] A book cover can be made of relatively thin board, which is generally used in different package cases.

[0012] In Figure 2a, all edges of cover blank 4 are provided with horizontal and vertical scorings and/or groovings 5, 6, which separate the cover side laps 7 from the remaining part of the blank. Back part 8 is also separated from the cover part by groovings 9. The back part groovings can be made either when making the cover or later in the production process of the bookbindery. The corners of the blank are chamfered at the corners of edge groovings 5, 6. After the cover blank is cut and creased, a book cover as shown in Figure 2b is made of the blank by folding all side laps 7 of the blank along groovings 5, 6 against the inner surface of the cover blank and by glueing together the opposed two board layers.

[0013] The folded edges 7 stiffen the whole periphery of the finished cover. They also have the effect that the cut board edge surfaces will not be edge surfaces in the finished cover. This prevents ply separation and tearing of cover edges as well as other changes in the board cross-section when using the book.

[0014] When using the described book covers in the production process, book manufacture takes place on a traditional adhesive binding line used in the manufacture of paperbacks. However, the bookblock must be cut to its final product size before binding it into the cover.

[0015] Figures 3a and 3b show a similar solution where a sleeve 10 is also used to have a loose back in the finished book. After making the cover in the way described above, sleeve 10 is glued to the inner side of the cover part. The sleeve width when flattened is preferably slightly more than the width of the book back, whereby a fold is formed on either side of the back to make it easier to open the book.

[0016] In Figures 4a and 4b is a variation of the solution shown in Figures 2a and 2b. In this application, all edges of the cover are folded. In addition, parts 11 to be folded around the vertical cover edges are so wide that they extend to the connection point between the back and cover. Side seamings provide the whole cover periphery with folded edges and a durable periphery is obtained. This prevents ply separations in the board and other such changes of the board's cross-sectional shape when the book is in use. The cover is double and sturdy. The book can be made either on an adhesive binding line or on a hard-cover line.

[0017] The solution shown in Figures 4a and 4b can be improved further by using a sleeve 10 in the back as shown in Figures 6a and 6b to prevent the back from breaking. In this variation, the folded parts may either end at the connection point between the cover and back or they may extend under the sleeve.

[0018] Figures 6a and 6b show a variation wherein parts 11 to be folded to the inside and which extend to the back are chamfered at their free vertical edges 12. This makes it easy to round off the back, because the seam will not tend to break the topmost board layer during mechanical rounding-off, where depending on the material one may use heat as a factor promoting rounding-off. The edge chamfer of the bent parts distributes the risk of breakage during bending of the board evenly to every part of the back structure. Thus the book is given the same appearance as a rounded-off hard-covered book. The book is made on a hard-cover line if the back is rounded off. If no rounding-off is done, an adhesive binding line may be used, whereby the bookblock is run to its final product size before casing-in.

[0019] In the variation shown in Figures 7a and 7b, part 11', which is folded around the vertical edge of the first cover, is so wide that it extends over the back to the second cover, all the way to the folded edge of the second cover. The part to be placed at the back part is separated by groovings 13. The cover is thus stiffened by one fold part and the back part is seamless. The second cover can also be made without any part to be folded.

[0020] Figures 8a and 8b show still another variation, wherein the cover corners are rounded off following the rounding-off of outer side corners done in the bookblock. In this application all the side fold alternatives and sleeve structures described above may also be used. The rounded-off corners provide the weakest cover parts with mechanical wear resistance. Rounding off can be done mechanically on hard-covered products. Earlier this was possible only with plastic products or as a multi-stage process with traditional hard covers.

[0021] Figure 9 shows a blank configuration, according to the invention, having two groovings 9, 9' at a distance from each other on both sides of back part 8. Foldable side laps 7 are dimensioned so that they cover the whole area of both the front cover and the back cover, except the surfaces between each grooving pair 9, 9' of the back part. At these surfaces there are gaps 14 between the side laps. This results in a thinner part at the bending point of the front cover and back cover which makes it easier to open the book.

[0022] The invention is not limited only to the application presented in the foregoing, but it may vary in different ways within the scope of the claims. If required, the inner cover surfaces may be lined with paper. If desired, different kinds of openings may be easily made in the covers by punching, through which openings, for example, part of the book's flyleaf can be seen. In this way various additional effects can be made to alter the book's appearance.

[0023] The invention can be applied not only when making book covers and books but also when making folders.

[0024] The material used for covers and folders may also be cardboard or paper, besides board. The sheet material may also be multi-layered and also a combination of these materials. A board-plastic laminate, for example, may also be used. Paper may be used, for example, in the application shown in Figure 7, whereby the paper folded double in the finished cover is equal to the thickness of unfolded board.

[0025] Instead of using glue or adhesive material which must be applied separately, the layers can be adhered to each other by heat-sealing the plastic-coated laminate surface against itself.

[0026] The invention may also be applied to booklet-type products having no proper back part.

[0027] The blank may be either sheet material or web material drawn directly from the roll.

Claims

1. A book or booklet including a leafblock and a cover part comprising a front cover, a back cover and a back (8) and formed of sheet or web material which is board, cardboard, paper or the like by folding and bringing the material layers fitted against each other to adhere to each other, whereby the cover part is formed by folding a one- or multi-layer sheet or web material blank (4) in one piece at all free edges (5, 6) of the front cover, back cover and back (8) against itself and by making the at least two material layers folded against each other to adhere to each other by means of adhesive material, whereby the folded parts are dimensioned so that they will not overlap on top of each other, and whereby at least on one side of the back part (8) there are two groovings (9, 9') at a distance from each other, characterized in that the folded parts (7) are dimensioned so that they cover the whole area of both the front cover and the back cover, except either wholly or in part the surfaces between each pair of groovings (9, 9') so that at least part of each area between each pair of groovings is thinner than those parts of the back part (8) adjacent to the said areas between each pair of groovings.

2. A book or booklet according to claim 1, characterized in that the stiffening of the back part (8) is formed by the two folded laps between the pairs of groovings (9, 9').

3. A book or booklet according to claim 1 or 2, characterized in that at least one of the covers is provided with at least one opening.

4. A book or booklet cover or a folder comprising a front cover, a back cover and a back (8) and formed of sheet or web material which is board, cardboard, paper or the like by folding and bringing the material layers fitted against each other to adhere to each other, whereby the cover or folder is formed by folding a one- or multi-layer sheet or web material blank (4) in one piece at all free edges (5, 6) of the front cover, back cover and back (8) of the cover or folder against itself and by making the at least two material layers folded against each other to adhere to each other by means of adhesive material, whereby the folded parts are dimensioned so that they will not overlap on top of each other, and whereby at least on one side of the back part (8) there are two groovings (9, 9') at a distance from each other, characterized in that the folded parts (7) are dimensioned so that they cover the whole area of both the front cover and the back cover, except either wholly or in part the surfaces between each pair of groovings (9, 9') so that at least part of each area between each pair of groovings is thinner than those parts of the back part (8) adjacent to the said areas between each pair of groovings.

5. A book or booklet cover or a folder according to claim 4, characterized in that the stiffening of the back part (8) is formed by the two folded laps between the pairs of groovings (9, 9').

6. A book or booklet cover or a folder according to claim 4 or 5, characterized in that at least one of the covers is provided with at least one opening.

7. A method of making a book or booklet cover or a folder of sheet or web material which is board, cardboard, paper or the like by folding and bringing the material layers fitted against each other to adhere to each other, whereby a one- or multi-layer sheet or web material blank (4) in one piece is folded at all free edges (5, 6) of the front cover, back cover and back (8) of the cover or folder against itself and the at least two material layers folded against each other are made to adhere to each other by means of adhesive material, whereby the parts to be folded are dimensioned so that they will not overlap on top of each other, and whereby at least on one side of the back part (8) there are two groovings (9, 9') at a distance from each other, characterized in that the folded parts (7) are dimensioned so that they cover the whole area of both the front cover and the back cover, except either wholly or in part the surfaces between each pair of groovings (9, 9') so that at least part of each area between each pair of groovings is thinner than those parts of the back part (8) adjacent to the said areas between each pair of groovings.

8. A method according to claim 7, characterized in that the stiffening of the back part (8) is formed by the two folded laps between the pairs of groovings (9, 9').

9. A method according to claim 7 or 8, characterized in that at least one opening is formed into at least one of the covers.

Ansprüche

1. Buch oder Broschüre, aufweisend einen Blätterblock und einen Einbandteil, der einen vorderen Deckel, einen hinteren Deckel und einen Rücken (8) aufweist und aus Blatt- oder Bahnmaterial, das Karton, Pappe, Papier oder dergleichen ist, gebildet ist durch Falten und Bringen der Materialschichten, die angepaßt sind, gegeneinander, um sie miteinander zu verbinden, wobei der Einbandteil gebildet ist durch Falten eines ein- oder mehrlagigen Blatt- oder Bahnmaterial-Zuschnitts (4) in einem Stück an allen freien Kanten (5,6) des vorderen Deckels, hinteren Deckels und Rückens (8) gegen sich selbst und durch Veranlassen, daß die wenigstens zwei Materialschichten, die gegeneinander gefaltet sind, aneinander haften vermittels eines Klebematerials, wodurch die gefalteten Teile so bemessen sind, daß sie nicht aufeinander überlappen, und wodurch wenigstens auf einer Seite des Rückenteils (8) zwei Rillen (9,9') unter einem Abstand voneinander vorgesehen sind, dadurch gekennzeichnet, daß die gefalteten Teile (7) so bemessen sind, daß sie den gesamten Bereich sowohl des vorderen Deckels als auch des hinteren Deckels abdecken, mit Ausnahme entweder vollständig oder teilweise der Oberflächen zwischen jedem Paar von Rillen (9,9'), so daß wenigstens ein Teil jedes Gebietes zwischen jedem Paar von Rillen dünner ist als diejenigen Teile des Rückenteils (8), die den Gebieten zwischen jedem Paar von Rillen benachbart sind.

2. Buch oder Broschüre gemäß Anspruch 1, dadurch gekennzeichnet, daß die Versteifung des Rückenteils (8) gebildet wird durch die zwei gefalteten Lagen bzw. Falze zwischen den Paaren von Rillen (9,9').

3. Buch oder Broschüre gemäß Anspruch 1 oder 2, dadurch gekennzeichnet, daß wenigstens einer der Deckel wenigstens mit einer Öffnung versehen ist.

4. Buch- oder Broschüreneinband oder -ordner, aufweisend einen vorderen Deckel, einen hinteren Deckel und einen Rücken (8) und gebildet aus Blatt- oder Bahnmaterial, das Karton, Pappe, Papier oder dergleichen ist, durch Falten und Bringen der gegeneinander gepaßten Materialschichten dazu, aneinander zu haften, wodurch der Einband oder Ordner gebildet ist durch Falten eines ein- oder mehrlagigen Blatt- oder Bahnmaterial-Zuschnitts in einem Stück an allen freien Kanten (5,6) des vorderen Deckels, hinteren Deckels und Rückens (8) des Einbands oder Ordners gegen sich selbst und durch Veranlassen, daß die wenigstens zwei Materialschichten, die gegeneinander gefaltet sind, aneinander haften vermittels eines Klebematerials, wodurch die gefalteten Teile so bemessen sind, daß sie nicht aufeinander überlappen bzw. überstehen, und wodurch wenigstens auf einer Seite des Rückenteils (8) zwei Rillen (9,9') unter einem Abstand voneinander angeordnet sind, dadurch gekennzeichnet, daß die gefalteten Teile (7) so bemessen sind, daß sie den gesamten Bereich sowohl des vorderen Deckels als auch des hinteren Deckels abdecken, mit Ausnahme entweder insgesamt oder zum Teil der Oberflächen zwischen jedem Paar von Rillen (9,9'), so daß wenigstens ein Teil jedes Gebiets zwischen jedem Paar von Rillen dünner ist als diejenigen Teile des Rückenteils (8), die den Gebieten zwischen jedem Paar von Rillen benachbart sind.

5. Buch- oder Broschüreneinband oder -ordner gemäß Anspruch 4, dadurch gekennzeichnet, daß die Versteifung des Rückenteils (8) gebildet ist durch die zwei gefalteten Lagen bzw. Falze zwischen den Paaren von Rillen (9,9').

6. Buch- oder Broschüreneinband oder -ordner gemäß Anspruch 4 oder 5, dadurch gekennzeichnet, daß wenigstens einer der Deckel mit wenigstens einer Öffnung versehen ist.

7. Verfahren zum Herstellen eines Buch- oder Broschüreneinbands oder eines -ordners aus Blatt- oder Bahnmaterial, das Karton, Pappe, Papier oder dergleichen ist, durch Falten und Bringen der gegeneinander gepaßten Materialschichten dazu, aneinander zu haften, wodurch ein ein- oder mehrlagiger Blatt- oder Bahnmaterial-Zuschnitt in einem Stück an allen freien Kanten (5,6) des vorderen Deckels, hinteren Deckels und Rückens (8) des Einbands oder Ordners gegen sich selbst gefaltet ist und die wenigstens zwei Materialschichten, die gegeneinander gefaltet sind, dazu gebracht werden, aneinander zu haften vermittels eines Klebematerials, wodurch die zu faltenden Teile so bemessen sind, daß sie nicht aufeinander überlappen bzw. überstehen und wodurch wenigstens auf einer Seite des Rückenteils (8) zwei Rillen (9,9') unter einem Abstand voneinander vorgesehen sind, dadurch gekennzeichnet, daß die gefalteten Teile (7) so bemessen sind, daß sie den gesamten Bereich sowohl des vorderen Deckels als auch hinteren Deckels abdecken, mit Ausnahme entweder insgesamt oder teilweise der Oberflächen zwischen jedem Paar von Rillen (9,9'), so daß wenigstens ein Teil jedes Gebiets zwischen jedem Paar von Rillen dünner ist als diejenigen Teile des Rückenteils (8), die den Gebieten zwischen jedem Paar von Rillen benachbart sind.

8. Verfahren gemäß Anspruch 7, dadurch gekennzeichnet, daß die Versteifung des Rückenteils (8) gebildet ist durch die zwei gefalteten Lagen bzw. Überlappungen bzw. Falze zwischen den Paaren von Rillen (9,9').

9. Verfahren gemäß Anspruch 7 oder 8, dadurch gekennzeichnet, daß wenigstens eine Öffnung in wenigstens einem der Deckel gebildet ist.

Revendications

1. Livre ou brochure incluant un bloc de feuilles et une partie couverture comprenant un plat avant, un plat arrière et un dos (8), et formée d'une matière filmée ou toilée qui est du carton, du papier ou équivalent en pliant et amenant les couches de matière les unes contre les autres pour adhérer les unes aux autres, d'où il résulte que la partie couverture est formée en pliant sur lui-même un flan (4) de matière filmée ou toilée, comportant une ou plusieurs couches, d'une seule pièce au niveau de tous les bords libres (5, 6) du plat avant, du plat arrière et du dos (8), et en faisant adhérer les unes aux autres les couches de matière pliées, au moins au nombre de deux, au moyen d'une matière adhésive, d'où il résulte que les parties pliées sont dimensionnées de telle sorte qu'elles ne se chevauchent pas les unes par dessus les autres, et d'où il résulte que sur un côté au moins de la partie dos (8) il existe deux rainurages (9, 9') à distance l'un de l'autre, caractérisé en ce que les parties pliées (7) sont dimensionnées de telle sorte qu'elles couvrent toute la surface à la fois du plat avant et du plat arrière, sauf totalement ou partiellement les surfaces comprises entre chaque paire de rainurages (9, 9') de sorte qu'une partie au moins de chaque surface comprise entre chaque paire de rainurages est plus mince que les parties de la partie dos (8) adjacentes auxdites surfaces comprises entre chaque paire de rainurages.

2. Livre ou brochure selon la revendication 1, caractérisé en ce que le renforcement de la partie dos (8) est réalisé par les deux volets pliés entre les paires de rainurages (9, 9').

3. Livre ou brochure selon la revendication 1 ou 2, caractérisé en ce qu'un des plats au moins est pourvu d'au moins une ouverture.

4. Couverture de livre ou de brochure, ou chemise, comprenant un plat avant, un plat arrière et un dos (8), et formée d'une matière filmée ou toilée qui est du carton, du papier ou équivalent en pliant et en amenant les couches de matière les unes contre les autres pour adhérer les unes aux autres, d'où il résulte que la couverture ou la chemise est formée en pliant sur lui-même un flan (4) de matière filmée ou toilée, comportant une ou plusieurs couches, d'une seule pièce au niveau de tous les bords libres (5, 6) du plat avant, du plat arrière et du dos (8) de la couverture ou de la chemise, et en faisant adhérer les unes aux autres les couches de matière pliées, au moins au nombre de deux, au moyen d'une matière adhésive, d'où il résulte que les parties pliées sont dimensionnées de telle sorte qu'elles ne se chevauchent pas les unes par dessus les autres, et d'où il résulte que sur un côté au moins de la partie dos (8) il existe deux rainurages (9, 9') à distance l'un de l'autre, caractérisée en ce que les parties pliées (7) sont dimensionnées de telle sorte qu'elles couvrent toute la surface à la fois du plat avant et du plat arrière, sauf totalement ou partiellement les surfaces comprises entre chaque paire de rainurages (9, 9') de sorte qu'une partie au moins de chaque surface comprise entre chaque paire de rainurages est plus mince que les parties de la partie dos (8) adjacentes auxdites surfaces comprises entre chaque paire de rainurages.

5. Couverture de livre ou de brochure, ou chemise, selon la revendication 4, caractérisée en ce que le renforcement de la partie dos (8) est réalisé par les deux volets pliés entre les paires de rainurages (9, 9').

6. Couverture de livre ou de brochure, ou chemise, selon la revendication 4 ou 5, caractérisée en ce qu'un des plats au moins est pourvu d'au moins une ouverture.

7. Procédé de fabrication d'une couverture de livre ou de brochure, ou d'une chemise, en matière filmée ou toilée qui est du carton, du papier ou équivalent, consistant à plier et à amener les couches de matière les unes contre les autres pour adhérer les unes aux autres, d'où il résulte qu'un flan (4) d'une seule pièce de matière filmée ou toilée, comportant une ou plusieurs couches, est plié sur lui-même au niveau de tous les bords libres (5, 6) du plat avant, du plat arrière et du dos (8) de la couverture ou de la chemise, et qu'on fait adhérer les unes aux autres les couches de matière pliées, au moins au nombre de deux, au moyen d'une matière adhésive, d'où il résulte que les parties à plier sont dimensionnées de telle sorte qu'elles ne se chevauchent pas les unes par dessus les autres, et d'où il résulte que sur un côté au moins de la partie dos (8) il existe deux rainurages (9, 9') à distance l'un de l'autre, caractérisé en ce que les parties pliées (7) sont dimensionnées de telle sorte qu'elles couvrent toute la surface à la fois du plat avant et du plat arrière, sauf totalement ou partiellement les surfaces comprises entre chaque paire de rainurages (9, 9') de sorte qu'une partie au moins de chaque surface comprise entre chaque paire de rainurages est plus mince que les parties de la partie dos (8) adjacentes auxdites surfaces comprises entre chaque paire de rainurages.

8. Procédé selon la revendication 7, caractérisé en ce que le renforcement de la partie dos (8) est réalisé par les deux volets pliés entre les paires de rainurages (9, 9').

9. Procédé selon la revendication 7 ou 8, caractérisé en ce qu'une ouverture au moins est formée dans au moins un des plats.

Drawing