Cardboard tray

A cardboard tray folded from an unfolded sheet of cardboard, which tray comprises:

• a bottom wall with a circumferential edge composed out of a number of straight edges;
• wall parts each arranged to a straight edge of the bottom wall;
• and
• first flange parts at least arranged to opposite wall parts along the circumferential edge, which first flange parts are arranged to an edge of said wall part opposite of, and preferably parallel to, the respective straight edge of the bottom wall;
• wherein the first flange parts comprise at least a first, a second and third elongate flange part section, which are connected parallel and along an elongate edge to each other,
• wherein, for each first flange part, the first elongate flange part section is arranged to a respective wall part, the second elongate flange part section is double folded against the first elongate flange part section, and the third elongate flange part section is connected parallel and along an elongate edge to the second elongate flange part section, and
• wherein for each first flange part the third elongate flange part section is adhered to the respective wall part on the inside of the cardboard tray and the second elongate flange part section is sloping downwards from the third elongate flange part section towards the first elongate flange part section, and the second elongate flange part section is configured to move to a horizontal position when a top seal foil under tension is applied to the first flange parts and, then subsequently, return to sloping downwards from the third elongate flange part section toward the first elongate flange part section.