Corrugated cardboard box with open-work flaps and set of blanks for obtaining same

1. A packaging box of polygonal section formed from at least two blanks of uncorrugated or corrugated cardboard sheet material, the at least two blanks comprising:

a first blank comprising a series of at least four main flaps terminated by a fixing tab, linked to each other by first fold lines parallel to each other, said series of at least four main flaps comprising two opposite flap(s), each having an opening arranged to authorize access for a user to the inside of the box, said series of at least four main flaps forming the external walls of the packaging box and being linked on one side to a series of flaps by second fold lines perpendicular to said first fold lines, said series of flaps forming the top of said packaging box, and

a second blank comprising a first central panel and four lateral second panels connected to said first central panel by third fold lines and connected together via flaps by fourth fold lines to form an external bottom tray for said packaging box,

wherein the first and second blanks are configured to form the packaging box by winding first and second blanks simultaneously around a first mandrel, the fourth fold lines being in contact and stretched on their whole length against and along the first fold lines by edges of said first mandrel with which they are in contact, so that the corner of the walls of said box and the corners of said bottom tray are formed by compression on each other,

wherein two panels are configured to be placed flat on opposite sides of a second mandrel,

wherein said second mandrel is configured to be lowered inside the packaging box, until it stops at the bottom, with said two panels parallel and in front of the two opposite main flaps of said first blank adjacent to said flaps having an opening, and

wherein the second mandrel is configured to be withdrawn upwards so as to obtain the packaging box with internal reinforcement on opposite walls formed by said flaps adjacent to said flaps having the opening.

2. The packaging box of claim 1 , wherein said main flaps having openings define a front wall and a rear wall, and wherein the packaging box further comprises:

a horizontal stiffening bar located proximate to a middle of a corresponding one of said openings in the at least one of said front wall and rear wall.

3. The packaging box of claim 1 , wherein the second blank comprises at least one of partially pre-cut portions and gluing points, wherein the first blank and the second blank are joined via the at least one partially pre-cut portions or gluing points, and wherein the joined first blank and second blank are configured to be separated by exerting a force perpendicular to the wall bearing said pre-cut portion or gluing point to be separated from.

4. The packaging box of claim 1 , wherein the at least four main flaps comprise front, rear and side walls separated from each other by intermediate walls to form an eight-sided packaging box with cut corners.

5. A method, comprising:

forming a packaging box from at least two blanks of uncorrugated or corrugated cardboard sheet material, namely a first blank to form the walls of the box and a second blank to form a bottom tray, each comprising panels connected together through vertical fold lines, wherein forming the packaging box includes winding the first and second blanks around a first mandrel simultaneously with the first and second blanks, the vertical fold lines of the second blank being in contact and stretched on their whole lengths against and along the vertical fold lines of the first blank by edges of said first mandrel with which they are in contact, so that the corner of the walls of said packaging box and the corners of said bottom tray are formed by compression on each other;

placing at least two reinforcing sheets flat on a second mandrel;

inserting the second mandrel with the at least two reinforcing sheets into the packaging box;

lowering the second mandrel and stopping the second mandrel at the bottom of the packaging; and

removing the mandrel from the packaging box such that the two reinforcing sheets remain inserted in the packaging box.

6. The method of claim 5 , wherein the packaging box comprises a front wall and a rear wall, each of said front wall and said rear wall comprising an opening arranged to authorize access for a user to the inside of the box, and wherein the method further comprises:

locating a horizontal stiffening bar proximate to a middle of a corresponding opening in the at least one of said front wall and rear wall.

7. The method of claim 5 , further comprising:

providing, on at least one of the at least two blanks, at least one of partially pre-cut portions or gluing points; and

joining the at least two blanks to each other via the at least one of partially pre-cut portions or gluing points, and separating the joined first blank and second blank by exerting a force perpendicular to the wall bearing said pre-cut portion or gluing point to be separated from.

8. The method of claim 5 , wherein forming the packaging box includes:

providing front, rear and side walls that are separated from each other by intermediate walls such that an eight-sided packaging box with cut corners is formed.

9. The method according to claim 5 , wherein the panels of the first blank are formed by at least four main flaps comprising two opposite flap(s), each having an opening arranged to authorize access for a user to the inside of the box, wherein said mandrel is lowered inside the packaging box, until it stops at the bottom, with said two reinforcing sheets parallel and in front of the two opposite main flaps of said first blank adjacent to said flaps having an opening, and

wherein the second mandrel is withdrawn upwards so as to obtain the packaging box with internal reinforcement on opposite walls formed by said flaps adjacent to said flaps having the opening.