EP3472056B1 - Method for producing a cardboard box - Google Patents

Description

Field of the invention

The present invention relates to a method of manufacturing window cover sheets for packaging boxes and to equipment for the automatic manufacture of such packaging boxes.

Various types of display packaging boxes provided with windows covered by transparent sheets are known in the state of the art. Such boxes allow effective presentation of their content.

State of the art

The general principle of the manufacture of such packaging boxes is known in the state of the art.

The French patent, registered under FR8026305 , described for example to a presentation box comprising an opening overlapping at least one edge, this opening is closed by a transparent rigid plastic sheet.

The transparent plastic window has notches at the end of the grooves corresponding to the edges of the box, so as not to cause the edges of the sheet to cooperate with the folding beads of the cardboard side of the box.

The certificate of addition filed under FR8113025 , relates to a method of manufacturing such boxes consisting in cutting a blank forming the box provided with an opening, in placing on this opening a sheet of plastic material transparent larger than this opening and to score this sheet to form the fold initiators.

The boxes thus obtained have greater rigidity than boxes known previously and comprising a sheet of flexible plastic material covering the window. They are, in particular, remarkable in that no bead is formed or tearing at the connection of the sheet and the cardboard blank, on the edges, thanks to the presence of notches extending beyond the edge of the window.

French patent FR2496052 describes another example of the manufacture of boxes, for example parallelepipedal boxes, comprising a window overlapping at least one edge of the box. According to this known solution, the window consists of an opening in the cardboard blank closed by a sheet of transparent rigid plastic material. The lines of the sheet corresponding to the edges of the box are weakened and their ends are indented in order to prevent the sheet from overlapping the folding beads of the blank.

• alimentation d'une laize continue de plastique rigide transparente dont la largeur correspond à la largeur déployée de la fenêtre;
• formation dans ladite laize continue d'une succession de découpes, les découpes étant réparties longitudinalement;
• formation sur ladite laize continue d'au moins une ligne de rainure longitudinale, passant par l'axe longitudinal médian desdites découpes longitudinales
• découpage de ladite laize, pour individualiser les fenêtres, selon une ligne de coupe transversale passant par le milieu d'une rangée de découpes longitudinales,
• application d'une ou de plusieurs pièces de fenêtre sur des flans en carton, l'adhésif sur chacune desdites une ou plusieurs pièces de fenêtre étant en contact avec un carton compact associé, et lesdites lignes de rainure étant alignées avec une des lignes de rainure dudit carton associé.

French patent FR2632610 A method of making window covering sheets for packaging boxes overlapping at least one edge of the box. The method consists in cutting notches in a film of rigid transparent plastic material, in bonding to the film thus prepared a flexible transparent plastic material film and in cutting out the cover sheets from this composite material thus formed. This patent discloses in particular a method of manufacturing a cardboard box comprising a rigid window made of a transparent material extending over at least two adjacent faces of the box comprising the following steps:

• feeding a continuous web of transparent rigid plastic whose width corresponds to the extended width of the window;
• forming in said continuous width of a succession of cutouts, the cutouts being distributed longitudinally;
• formation on said continuous web of at least one longitudinal groove line passing through the median longitudinal axis of said longitudinal cutouts
• cutting of said width, to individualize the windows, along a transverse section line passing through the middle of a row of longitudinal cuts,
• applying one or more window pieces to paperboard blanks, the adhesive on each of said one or more window pieces being in contact with an associated solid board, and said groove lines being aligned with one of the groove lines of said associated carton.

We also know the French patent FR2638393 describing a cutout of a transparent blank, for the manufacture of a window packaging box, the body of which is made of cardboard.

The transparent strip circulates continuously until the final cutting after cutting the notches for folding in the corners of the cardboard.

French patent FR2507155 describes another example of a transparent box made from a polyvinyl chloride sleeve and at least one cardboard sleeve provided with tabs for closing one end of the transparent tube. The assembly by gluing of the two sleeves makes it possible to obtain a transparent sleeve and an opaque bottom.

The patent application DE9012578 relates to a folding box with a cardboard body part with a window opening with an insert, extending over at least two fold lines, inside the window of a transparent, rigid, made of window film made of plastic material whose structural strength substantially equal to that of the cardboard box and with the window environment forms a first frame-shaped covering area, in which the window sheet is fixedly connected to the housing, in which the sheet window extends in the direction of the fold lines on at least one side of the window in a second overlapping area in which the window sheet has no connection to the cardboard box and is also located on either side of two lines folding, and wherein the body part within the second unbound overlap area has a line of weakness located in a housing comprising.

Disadvantages of the prior art

The solutions of the prior art lead to the formation of a cutout at the junction of the window and the cardboard which is very visible and unsightly. These cuts generally have a triangular shape. Furthermore, the position of this triangular cutout results in a visible variation of the base of the cutout, depending on the precision of the position of the window in relation to the cardboard.

If the position of the window is not perfectly centered in relation to the light formed in the card, the difference in width of the bases of the triangular cutouts on one side and the other is clearly visible and gives a poor quality appearance .

In addition, for boxes of small dimensions, the triangular cutouts reduce the gluing surface of the window on the cardboard.

Solution provided by the invention

In order to remedy these drawbacks, the invention relates to a method of manufacturing a cardboard box comprising a rigid window in a transparent material according to claim 1.

• Un choix dimensionnel de la taille des découpes permettant de concilier les deux contraintes (découpes peu visibles, mais assurant leur fonction de permettre le pliage au niveau du raccordement de deux matériaux ayant des caractéristiques mécaniques très différentes)
• Une succession d'étape prévoyant la formation des découpes et le rainurage de la feuille en plastique transparente avant la découpe des fenêtres.

The invention differs from the prior art by:

• A dimensional choice of the size of the cutouts making it possible to reconcile the two constraints (hardly visible cutouts, but fulfilling their function of allowing bending at the level of the connection of two materials with very different mechanical characteristics)
• A succession of stages providing for the formation of the cutouts and the grooving of the transparent plastic sheet before cutting the windows.

Preferably, the step of forming said cutouts is carried out by an abrasive disc.

Advantageously, the zone for forming said cutouts and / or grooving is heated.

According to a variant, the dust and chips are sucked in at the region where said longitudinal cuts are formed.

The invention also relates to equipment for the manufacture of a cardboard box comprising a rigid window of transparent material according to claim 5.

Preferably, said longitudinal cut-out forming station comprising abrasive discs.

According to a particular embodiment, the equipment according to the invention comprises a carriage adjustable in depth for alternately forming the longitudinal cuts and the grooving of the continuous web, said carriage being controlled by a programmable controller for synchronization with the movement. advance of the continuous width, depending on the length of the window.

The cardboard box obtained by the method of the invention comprises a rigid window in a transparent material extending over at least two adjacent faces of the box, said window having at least one groove extended on either side by a cutout characterized in that said cutouts have a length of between 20 and 35 millimeters and a width less than 3 millimeters, the cutouts being distributed longitudinally with a pitch corresponding to the length of the window and laterally as a function of the widths of said adjacent faces.

Detailed description of a non-limiting example of the invention

• la figure 1 représente une vue dépliée d'un carton selon l'invention
• la figure 2 représente une vue agrandie de la zone A
• la figure 3 représente une vue schématique d'un équipement selon l'invention.

The present invention will be better understood on reading the detailed description of non-limiting embodiments with reference to the appended drawings where:

• the figure 1 shows an unfolded view of a carton according to the invention
• the figure 2 shows an enlarged view of area A
• the figure 3 represents a schematic view of equipment according to the invention.

Description of the box according to the invention

The box according to the invention consists of a cardboard blank (100) on which is glued a transparent plastic window (50).

The cardboard blank (100) is cut and grooved to present four side faces (10, 20, 30, 40) extended by upper legs (11, 21, 31, 41) and lower legs (12, 22, 32, 42) forming the upper and lower bottoms when the box is shaped. A side flap (13) allows the side faces to be closed by gluing.

On this cut blank (100) is glued a PVC or PET window, covering the main face (20) by a central zone (52) and partially covering the lateral faces (10, 30) by lateral zones respectively (41, 53 ).

The plastic sheet (50) is cold or hot grooved by grooves (54, 55) facilitating the folding of the plastic window, relatively rigid, during the shaping of the assembly after gluing on the blank cardboard-based.

The window (50) has, at the ends of each groove (54, 55), a rectangular cutout (57) extending from the peripheral edge of the window to the limit of the cutout formed in the cardboard blank. . The height of this cutout (57) is slightly greater than the width of the bonding surfaces (15, 25) where the plastic sheet (50) is superimposed on the cardboard blank (100). Typically, the height of the cutout (57) is between once and 1.1 times the width of this overlapping zone (15, 25), the width of which is typically of the order of 12 millimeters. The width of the cutout (57) is of the order of 1.5 millimeters for a window of small thickness, typically 3 millimeters.

Description of the equipment according to the invention

The equipment for the manufacture of such boxes comprises a vacuum conveyor belt (205) driving the continuous web (200) from an unwinder (201). The width of the width (200) corresponds to the width of the window.

A first station (210) comprises means for forming the alignments of cutouts, by consecutive transverse series. These cutouts have a height that is double the final cutout of a window (50), ie 20 to 40 millimeters.

These cuts can be formed by abrasive discs rotating at high speed, more than 50,000 revolutions per minute. They can also be formed by water jet cutting, laser or any other means.

This station operates synchronously with the scrolling of the width (200) to produce a line of cutouts (57) at regular pitches corresponding to the width of the window (50).

The abrasive disc is mounted on a carriage adjustable in depth to successively perform the cutting and the groove of the PVC window, and is synchronized with the advance movement of the reel, depending on the length of the window.

The speed of advancement of the web is controlled by a servomotor controlled by a programmable controller in order to determine the pitch between each.

The next station (220) performs the hot or cold grooving to form on the width (200) the grooved lines (54, 55) continuously. These lines pass through the longitudinal cuts made in the previous station (210).

Optionally, the making of the cutouts and the grooving can be done in one and the same station.

The width (200) thus cut and grooved then passes through a station (230) making a transverse cut to individualize the windows. These cuts pass through the middle of the alignments of longitudinal cuts.

It should be noted that the grooving station (220) can be located upstream or downstream of the cutting station (210).

Then, a receiving station (240) stacks the prepared windows and an unstacker collects them one by one to move them on a cardboard blank and perform the gluing.

Claims (7)

1. Method for producing a cardboard box comprising a rigid window made of a transparent material extending over at least two adjacent faces (10, 20, 30) of the box, comprising the following steps:

   - supplying a continuous width (200) of transparent rigid plastics material, the width of which corresponds to the width used for the window (50);

   - forming, in said continuous width (200), a succession of longitudinal cutouts (57) having a length between 20 and 35 millimeters and a width less than 3 millimeters, said cutouts being distributed longitudinally with a pitch corresponding to the length of the window (50) and laterally according to the widths of said adjacent faces

   - forming, on said continuous width (200), at least one longitudinal groove line which passes through the central longitudinal axis of said longitudinal cutouts

   - cutting said width (200), in order to individualize the windows (50), along a cross-sectional line passing through the middle of a row of longitudinal cutouts

   - applying one or more window pieces (50) to cardboard blanks, the adhesive on each of said one or more window pieces (50) being in contact with an associated solid fiberboard, and said groove lines being aligned with one of the groove lines of said associated fiberboard.
2. Method for producing a cardboard box comprising a rigid window (50) according to claim 1, characterized in that the step of forming said longitudinal cutouts is carried out by an abrasive disk.
3. Method for producing a cardboard box comprising a rigid window (50) according to the preceding claim, characterized in that the formation zone for said cutouts is heated.
4. Method for producing a cardboard box comprising a rigid window (50) according to claim 1, characterized in that dust and chips are sucked up in the formation zone for said cutouts.
5. Equipment for producing a cardboard box comprising a rigid window (50) made of a transparent material extending over at least two adjacent faces of the box, comprising:

   - a suction belt for moving a continuous width (200) of rigid transparent plastics material

   - a station for forming, in said continuous width, a succession of longitudinal cutouts having a length between 20 and 35 millimeters and a width less than 3 millimeters, said cutouts being distributed longitudinally with a pitch corresponding to the length of the window (50) and laterally according to the widths of said adjacent faces

   - a station for grooving said continuous width

   - a station for transversely cutting said continuous width along a cross-sectional line passing through the middle of a row of longitudinal cutouts

   - a station for applying one or more window pieces (50) to cardboard blanks, the adhesive on each of said one or more window pieces (50) being in contact with an associated solid fiberboard, and said groove lines being aligned with one of the groove lines of said associated fiberboard.
6. Equipment for producing a cardboard box according to the preceding claim, characterized in that said station for forming the longitudinal cuts comprises abrasive disks.
7. Equipment for producing a cardboard box according to claim 5, characterized in that it comprises a carriage which is adjustable in depth in order to alternately carry out the formation of the longitudinal cutouts and the grooving of the continuous width, said carriage being controlled by a programmable controller for synchronization with the feed movement of the continuous width, according to the length of the window (50).

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