EP1033241A1 - Rigid corrugated cardboard - Google Patents

Abstract

Fluted sheet is assembled with first covering sheet to form lap. Second covering sheet is placed on side of lap. Desired profile is given to lap and second covering sheet by moving them along desired core. Core has circular or rectangular cross-section. An Independent claim is also included for the description of machine to manufacture corrugated cardboard.

Description

The present invention relates to a method of manufacturing a rigid corrugated cardboard, a rigid corrugated cardboard obtained by this process and a machine for making rigid corrugated cardboard.

It applies more particularly to the boxes necessary for the manufacture of packaging or packaging.

Corrugated cardboard, of the classic type, is a complex material consisting of two to seven sheets of paper. The leaves are called "Covers" when they are outside and "medians" when they are interior. Fluted or wavy sheets can form spacer and are glued to the sheets mentioned above and called "grooves".

• Un type de carton ondulé peut être assimilé à une structure souple. Ce type de carton ondulé est le carton ondulé simple face appelé « nappe simple face ». Une telle nappe est constituée d'une couverture simple face de faible épaisseur et d'une cannelure solidarisée par des points de colle sur les crêtes de cannelure en contact avec la couverture.

Without limitation, we can classify corrugated cardboard in two categories:

• A type of corrugated cardboard can be likened to a flexible structure. This type of corrugated cardboard is single-sided corrugated cardboard called "single-sided tablecloth". Such a sheet consists of a single-sided cover of small thickness and a groove joined by dots of glue on the groove ridges in contact with the cover.

This cardboard has the advantage of being able to be curved at will, particularly rolled up, without being folded. It is stored in a roll and used especially as wedging, support for various panels.

• Tous les autres cartons ondulés peuvent être assimilés à une structure rigide. On peut citer, par exemple, le carton ondulé double face constitué d'une cannelure collée et intercalée entre une couverture simple face de faible épaisseur et une couverture double face de forte épaisseur, ou le carton ondulé double face constitué de deux cannelures collées et intercalées entre deux couvertures simple face de faible épaisseur et une couverture double face de forte épaisseur.

A disadvantage of this cardboard is that it is not resistant since, by definition, it does not have a sandwich type structure. It cannot therefore be used directly as part of a package and its applications are limited.

• All other corrugated cardboard can be compared to a rigid structure. Mention may be made, for example, of double-sided corrugated cardboard made up of a glued groove inserted between a thin single-sided cover and a double-sided cover very thick, or double-sided corrugated cardboard made of two glued and interposed grooves between two thin single-sided blankets and a thick double-sided blanket.

As soon as they are produced, the boxes are cut into plates and therefore dishes. They are resistant and can be used as part of a packaging, such as a box, the edges of which are the result of fold lines of said cartons.

A disadvantage of this type of cardboard is that before it can be used as part of a package, it must undergo one or more creasing, operation which consists in partially crushing along a line the entire thickness of the corrugated cardboard to facilitate subsequent folding of the flaps. These two categories of corrugated cardboard therefore each have their own its own characteristics, namely flexibility and curvature for the first of these categories, stiffness and flatness for the second.

Document FR 2 668 099 discloses a method of manufacture of a semi-cylindrical cell shell made of cardboard wavy, shell which can be compared to a third category of corrugated since both rigid and curved. This process consists of glue a double-sided cover sheet on the grooves of a strip of single-sided corrugated cardboard in an area where the strip is already curved on a roller.

Such a process is advantageous since it is carried out continuously on a line industrial. It allows a significant flow of shells. The shells obtained are inexpensive, light and robust and their use is very simple. However, the applications of these shells are restricted by a very particular geometry and are limited to the wedging of cylindrical objects, for example bottles lying in a packing box.

We know from WO 98/50226, a method of manufacture of rigid corrugated cardboard in which, from a sheet single face of given width and length, we perform an operation for bending the tablecloth, for gluing the tops of the tablecloth groove curved then gluing a cover of width and length adapted to that of the single-sided sheet so that said cover follows the curved shape of the tablecloth. Bending is carried out by winding of the web on a sleeve which will give the cardboard its final form. To allow this winding or winding, the tablecloth grooves are provided in the direction perpendicular to that of its displacement. This process is not suitable for manufacturing in continued.

The object of the present invention is to remedy the drawbacks of the methods described above.

The object of the present invention is to propose a method of continuous production of rigid corrugated cardboard of various shapes.

The method according to the invention is intended for the manufacture of a cardboard corrugated rigid. A fluted sheet with flutes is continuously formed longitudinal, we assemble the fluted sheet and at least a first cover sheet thus forming a sheet, at least one second cover sheet on one side of the tablecloth, and we give the tablecloth and on the second cover sheet a desired profile using of a shape along which said sheet and said second sheet of cover are moved.

Advantageously, the tablecloth and the second cover sheet are assembled when they pass along the form.

Advantageously, the shape is a mandrel on which one slides cover sheets.

In general, the mandrel can in particular be of section substantially polygonal, for example substantially triangular, symmetrical or not, substantially square, substantially rectangular, of preferably with rounded angles, or more generally of section which follows a closed geometric curve with concave and / or convex portions. It can have an essentially curved outline, in particular convex to variable radius of curvature, for example oval or elliptical, or combining concave and convex portions, with possible connections angular between the portions of different radii of curvature, the angles can be more or less rounded. Finally, the mandrel can have any complex shape combining straight portions and curves of curvature variables. The process is particularly advantageous for all forms more complex than the circle, without symmetry of revolution.

In one embodiment of the invention, the mandrel is circular or rectangular cross section.

In one embodiment of the invention, the first sheet of cover is in contact with the shape.

In one embodiment of the invention, the second sheet of cover is in contact with the shape.

In one embodiment of the invention, the second sheet of cover is in contact and secured to the first sheet of blanket.

In another embodiment of the invention, the second cover sheet is in contact and secured to the fluted sheet.

Advantageously, each of the cover sheets is of width greater than that of the fluted sheet. The edge of each sheet of cover can be assembled with the opposite edge of the same sheet of cover, without extra thickness.

The present invention also relates to a corrugated cardboard rigid obtained by a process as described above. This carton can be used in particular as a rectangular box or packaging cylindrical, or any other shape.

The present invention also relates to a machine for manufacture of rigid corrugated cardboard. The machine includes a means to continuously form a grooved sheet with longitudinal grooves, means for assembling the fluted sheet and at least a first cover sheet thus forming a sheet, a means for bringing to the minus a second cover sheet on one side of the tablecloth, and one means to give the tablecloth and the second cover sheet a desired profile by means of a shape along which said sheet and the said second cover sheet are moved.

Advantageously, the machine comprises a means for assembling the tablecloth and the second cover sheet as they pass along of shape.

Advantageously, the shape is a mandrel around which slides one of the cover sheets.

In one embodiment of the invention, the means for forming a fluted sheet with longitudinal flutes comprises plates longitudinally grooved between which the fluted sheet is moved.

The rigid corrugated cardboard according to the invention is economical thanks to its continuous production and has mechanical characteristics particularly interesting in the case of packing cases parallelepipedic or at least at sharp angles whose angles are obtained during manufacturing and not by creasing and folding a flat piece of cardboard, hence the elimination of the zone of weakness that was the sharp corner where the cardboard structure was locally crushed.

Different types of grooves can be used in the process of manufacture according to the invention. Splines can be profile sinusoidal or triangular, trapezoidal or rectangular. These two latest profiles allow a significant increase in characteristics mechanical properties of the cardboard, in particular resistance to crushing. Of asymmetrical profiles combining the above profiles can also be used.

• la figure 1 est une vue en coupe transversale d'un carton obtenu selon le procédé conforme à l'invention ;
• la figure 2 est une vue en perspective d'une machine de fabrication de carton ondulé, conforme à l'invention ;
• la figure 3 est une variante de la figure 1 ;
• la figure 4 est une vue en perspective d'un détail de la figure 1 ;
• les figures 5a, 5b et 5c sont des vues en coupe transversale d'une cannelure ;
• les figures 6a, 6b, 6c, 6d et 6e sont des vues en perspective d'autres formes de carton obtenues selon le procédé conforme à l'invention.

The present invention will be better understood and other advantages will appear on reading the detailed description of some embodiments taken by way of non-limiting examples and illustrated by the appended drawings, in which:

• Figure 1 is a cross-sectional view of a carton obtained according to the method according to the invention;
• Figure 2 is a perspective view of a machine for manufacturing corrugated cardboard, according to the invention;
• Figure 3 is a variant of Figure 1;
• Figure 4 is a perspective view of a detail of Figure 1;
• Figures 5a, 5b and 5c are cross-sectional views of a groove;
• Figures 6a, 6b, 6c, 6d and 6e are perspective views of other forms of cardboard obtained according to the method according to the invention.

As can be seen in Figure 1, the rigid corrugated board obtained thanks to the invention is in the form of a tube.

In the example of Figure 1, this tube is of circular section.

The rigid corrugated cardboard includes an inner cover 1, a outer cover 2 and a groove 3 disposed between the covers indoor 1 and outdoor 2.

For example, the inner cover 1 can be made of white top paper with a grammage equal to 140 g / m ² , the groove 3 can be made of bleached kraft paper with a grammage equal to 140 g / m ² with corrugations preferably of type E, type F, type N, and the outer cover 2 can be in white coated writing paper printed with a grammage equal to 230 g / m ² . The ends 1a and 1b, 2a and 2b of the interior covers 1 and exterior 2, are respectively glued to each other with a slight overlap.

FIG. 2 shows a first embodiment of a rigid corrugated cardboard making machine, in accordance with the invention, and intended to produce rigid corrugated boxes of the type illustrated on the Figure 1. The machine comprises an axis 4 on which is arranged a reel of paper 5 whose sheet of paper 9 unwinds in the direction of the arrow 6 and passes between two forming plates 7 and 8.

Plates 7 and 8 are positioned relative to each other of so as to create between them a space in which the sheet of paper moves paper 9 coming from the reel 5. The sheet of paper 9 is introduced between the plates 7 and 8 in flat configuration and gradually deforms, at during its path, between said plates 7 and 8.

The surfaces of the plates 7 and 8, facing each other, are profiled so as to make the grooves. At the exit of the plates 7 and 8, the profile of the sheet 9 corresponds exactly to the groove desired. Downstream of the plates 7 and 8, the groove thus formed carries the reference 10.

The splines can be made simultaneously on the entire width of sheet 9 or alternatively, starting from a given ripple followed by the other ripples, in an order that can vary depending on the profile of plates 7 and 8. For example, you can first form a central undulation located transversely in the middle of sheet 9 or one of the two lateral undulations, depending characteristics of the paper forming the sheet 9. The profiles of the plates 7 and 8 reproduce, on request, undulations of different shapes: triangular, sinusoidal, trapezoidal, rectangular, etc.

This possibility of deviating from the conventional sinusoidal profile allows increase the mechanical performance of the cardboard box body as well got. For comparable mechanical performance, some of these profiles can lead to significant material gains therefore better optimization of materials used.

Plates 7 and 8 can be heated and their length will depend characteristics of sheet 9 and the geometry of the corrugations achieve. Plates 7 and 8 can be fitted with a supply device humidity control.

The machine also includes an axis 11 parallel to axis 4 and supporting a reel of paper 12, which unwinds in the direction of the arrow 13. The sheet of paper 14 coming from the reel 12 passes through a deflection roller 15, then approaches the groove 10. The groove 10 and the sheet 14 pass together between two rollers 16 and 17. The roller 16, in the lower position, is in contact with the strip 14 and the roller 17 in the upper position, is in contact with the groove 10. The roller 16 is smooth, while roller 17 has a grooved profile reproducing the corrugations of the groove 10. The roller 17 can also be formed of a set of rollers. Rollers 15, 16 and 17 are parallel to the axis 4. Thus, at the outlet of the plates 7 and 8, the groove 10 is immediately laminated to sheet 14 which scrolls at the same speed. The gluing means, not shown, will be arranged so to apply glue, either on the groove 10, or on the strip 14, on one of their facing surfaces. Rollers 16 and 17 apply, under adjustable pressure, the groove 10 on the sheet 14, which allows to obtain a perfect lamination. We thus form at the exit of the rollers 16 and 17, a single-sided ply 18 composed of the groove 10 on its upper surface and flat sheet 14 on its lower surface.

The sheet 18 is a flexible and deformable structure transversely. The sheet 18 is then driven towards a forming mandrel 19 which is in the form of a cylinder of longitudinally oriented revolution in the direction of movement of the tablecloth 18. The mandrel 19 is visible only on the left side of the figure 2, but it will be understood that it extends under the sheet 18.

The machine also includes an axis 20 parallel to axis 4 and supporting a reel of paper 21 which unwinds in the direction of the arrow 22. The flat sheet 23 coming from the reel 21 passes through a roller 24 parallel to axis 4 and arranged under the ply 18. The ply 18 comes gradually wind around the mandrel 19 while deforming gradually transversely. Its cross section beforehand plane rounds following the circular shape of the mandrel. To perfect this winding, we can provide conformers, not shown, allowing good application of the ply 18 on the mandrel 19. The conformers may be in the form of rollers and / or belts. The sheet 18 thus comes to be wound progressively while transversely deforming, around the mandrel 19, the sheet 14 being in contact with said mandrel 19 and the groove 10 being disposed at outside.

The transverse ends or edges of the ply 18 come in contact with each other and are laminated longitudinally. Their overlap width, adjustable, is determined by the parameters of finish and functionality of the final product. Then sheet 23 enters in contact with the groove 10 which forms the outer surface of the sleeve which has thus been formed around the mandrel 19. The sheet 23, after passing through the deflection roller 24, follows a path parallel to that of the ply 18 and is wound progressively by deformation transverse and longitudinal displacement around the ply 18 formed in sleeve, to which it is laminated.

The transverse free ends of the sheet 23 are provided with variable overlap dictated by finishing parameters and functionality of the final product. Again, sheet 23 is guided after the roller 24 by belts, not shown, which conform to the shape of the mandrel 19 and ensure perfect assembly of the different sheets. We thus forms a cylindrical tube 25 of section similar to that of cardboard illustrated in Figure 1. This tube is then cut transversely to desired dimensions and faithfully retains the shape of the mandrel which give birth. The tube sections thus cut then pass to a finishing station, not shown, where they receive cover, bottom, handle, membrane, etc.

In Figure 3 is illustrated an embodiment slightly different from that of FIG. 2. The machine thus represented has differences, especially after the formation of the ply 18 by passage between the rollers 16 and 17. An axis 26 parallel to the axis 4 arranged above of the sheet 18 supports a reel of paper 27 from which a sheet 28 unrolls in the direction of arrow 29, thus approaching the ply 18. A mandrel 30, identical in shape to that of the mandrel 19 of Figure 2, is arranged longitudinally in the direction of movement of the ply 18, transversely in the middle of said ply 18.

In Figure 3, we see the free end 30a of the mandrel 30 to proximity of the rollers 16 and 17. The ply 18 passes under the mandrel 30 with the groove 10 arranged on the side of the mandrel 30 and the sheet 14 to the opposite. The sheet 29 passes near the end 30a of the mandrel 30 by a roller, not shown, whose function is identical to that of roller 24 of Figure 2, i.e. to allow a change orientation of sheet 28 and give it a trajectory parallel to that of the tablecloth 18.

The sheet 28 comes to wrap around the mandrel 30 while deforming transversely being guided by conformers, not represented. The free edges of the sheet 28 are provided with a slight overlap and are laminated to each other. Then tablecloth 18 wraps longitudinally, deforming transversely around the sleeve formed by the sheet 28. The groove 10 is oriented towards inside, in contact with sheet 28, while sheet 14 is arranged outside. The fluted side of the sheet 18 is laminated on the strip 28. The width of overlap of the edges of the ply 18 will depend on the finish and functionality of the finished product.

As before, the tube 31 thus formed is guided throughout along its path on the mandrel 30 by belts, not shown, conforming to the shape of the latter and which ensure a perfect assembly of three layers. The assembly being carried out by gluing and application of pressure.

Another embodiment, not shown, can be envisaged. The order of overlapping of the sheets is identical to that illustrated on the figure 3. A flat sheet is first wound on the mandrel, then a tablecloth composed of a flat sheet and a groove comes wind, but the difference is that the groove is oriented outside and the flat sheet is oriented inside the side of the sleeve already formed by the other flat sheet. The tube that is so manufactured is stable but less rigid than those of the embodiments previous. It offers different visual characteristics which can be sought after for certain applications.

In FIG. 4, we see more particularly the stage of formation of the ply 18. At the outlet of the forming plates 7 and 8, the groove 10 which just formed continues its horizontal longitudinal movement in the direction of arrow 32. The sheet 14 rotates around the roller 16 of the figure 2 which has been omitted in figure 4 for reasons of readability and understanding of the drawing, and comes to rest against the lower surface of the groove 10. The sheet 14 is expected to be slightly wider greater than that of the groove 10, so that it has an edge free 14a which is not in contact with the groove. This strip 14a free of groove is, when winding the web 18 around the mandrel, glued on its opposite edge. The thickness of the junction area between the two edges of the ply 18 is therefore reduced by the thickness of the groove, which makes it possible to obtain a finished product more regular forms. This improvement in shape results in a increased tightness of the tube, which can allow better conservation items that will later be packed in the carton and a better mechanical strength of the carton itself.

In FIGS. 5a, 5b and 5c, three types of grooves are illustrated obtainable by passing between forming plates and being then used to form the carton. In FIG. 5a, is illustrated a classic sine groove. In FIG. 5b, a a groove with a trapezoidal profile and in FIG. 5c, a groove with rectangular or crenellated profile. These last two profiles are likely to significantly increase the mechanical characteristics of the tube and by there bodies of boxes. Of course, asymmetrical profiles combining the above profiles can also be manufactured.

The application illustrated in Figures 1 to 3 is that of cardboard boxes. circular shape. It will be understood that the same process can be used to make rectangular boxes using a mandrel of rectangular section, which can make it possible to form boxes in rectangular board with high mechanical resistance because formed without folding or crushing (creasing) of certain corrugations for folding.

In other applications, section tubes could be provided triangular, square, hexagonal, etc.

Figures 6a, 6b, 6c, 6d and 6e thus illustrate various forms accessible with the method according to the invention. These forms which have no symmetry of revolution are of continuous realization as easy as the circular shape, while conventional methods are less efficient, especially in terms of cadence, for these so-called forms complex.

• la figure 6a présente un carton ondulé tubulaire à section ovale ;
• la figure 6b présente un carton ondulé tubulaire à section triangulaire sensiblement isocèle dont les angles sont légèrement arrondis, la forme extérieure du mandrin étant adaptée en conséquence, cette forme de mandrin sans arêtes vives permettant un glissement facilité des feuilles de couverture sur le mandrin. En variante, les côtés du triangle pourraient être courbes, la section du tube étant continûment convexe ;
• la figure 6c présente un carton tubulaire à section carrée avec des coins arrondis ;
• la figure 6d présente un carton tubulaire dont la section inclut deux portions de cercle accolées reliées par point anguleux légèrement arrondi ;
• la figure 6e présente un carton tubulaire de section complexe incluant deux rectangles reliés entre eux par une portion droite plus étroite.

So :

• Figure 6a shows a tubular corrugated cardboard oval section;
• FIG. 6b presents a tubular corrugated board with a substantially isosceles triangular section, the angles of which are slightly rounded, the external shape of the mandrel being adapted accordingly, this shape of mandrel without sharp edges allowing easy sliding of the cover sheets on the mandrel. As a variant, the sides of the triangle could be curved, the section of the tube being continuously convex;
• Figure 6c shows a tubular cardboard square section with rounded corners;
• FIG. 6d presents a tubular carton, the section of which includes two contiguous circle portions connected by slightly rounded angular point;
• FIG. 6e presents a tubular carton of complex section including two rectangles linked together by a narrower straight portion.

In all the preceding cases, the mandrel has a shape corresponding to the tube section and the conformers are adapted in result.

These are just a few examples of all the forms accessible and achievable with the same ease with the process of the invention.

We can thus use boxes made of thinner sheets hence saving material and reducing mass, or transport higher loads or stack the boxes on a higher height.

Claims (16)

Method for manufacturing rigid corrugated cardboard, in which continuously forms a fluted sheet with longitudinal flutes, assembles the fluted sheet and at least a first sheet of cover thus forming a sheet, we bring at least a second cover sheet on one side of the tablecloth, and the tablecloth and the second cover sheet a desired profile by means of a form the along which said tablecloth and said second cover sheet are moved. The method of claim 1, wherein the web and the second cover sheet are assembled during their passage on along the form. The method of claim 1 or 2, wherein the form is a mandrel on which one of the cover sheets slides. The method of claim 3, wherein the mandrel is circular or rectangular cross section. The method of claim 3, wherein the mandrel has a section which follows a closed geometric curve with concave portions and / or convex, in particular has a shape without symmetry of revolution. Method according to any one of the preceding claims, wherein the first cover sheet is in contact with the shape. Method according to any one of the preceding claims, wherein the second cover sheet is in contact with the shape. Method according to any one of the preceding claims, in which the second cover sheet is in contact and secured with the first cover sheet. Process according to any one of Claims 1 to 7, in which the second cover sheet is in contact with and secured to the fluted sheet. Method according to any one of the preceding claims, wherein each of the cover sheets is wider than that of the fluted leaf. Method according to any one of the preceding claims, in which the edge of each cover sheet is assembled with the opposite edge of the same cover sheet. Rigid corrugated cardboard, characterized in that it is obtained by a method according to any one of the preceding claims. Rigid corrugated cardboard making machine, characterized by the fact that it comprises means (7, 8) for continuously forming a grooved sheet (10) with longitudinal grooves, means (16, 17) for assembling the fluted sheet and at least one first sheet (14) of cover thus forming a sheet (18), a means for bringing to the at least a second cover sheet (23) on one side of the tablecloth, and a means for imparting to the tablecloth and to the second cover sheet a desired profile by means of a shape (19) along which said tablecloth and said second cover sheet are moved. Machine according to claim 13, characterized in that that it includes a means for assembling the sheet and the second cover sheet as they pass along the form. Machine according to claim 13 or 14, characterized by the makes the shape a mandrel around which one of the sheets of blanket. Machine according to any one of Claims 13 to 15, characterized in that the means for forming a fluted sheet at longitudinal splines includes grooved plates longitudinally between which the fluted sheet is moved.

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