Device for covering packaging boxes

A packaging box covering device for covering a free edge intermediate between an outside surface and an inside surface of a wall of a box, the device comprising one or more elements for folding a flap of a covering sheet around the intermediate edge so that the flap is made to cover the edge and then applying the flap to the inside surface of the wall;

• the folding elements comprising at least one wing rotatably mounted, with a return spring, on a pin attached to a support mobile at right angles to the wall, the device further comprising a guide recess in which the wing slides in a first closed configuration, the wing being driven in a straight line at right angles to the wall until said wing is outside the guide recess and rotationally, under the action of the spring about an axis parallel to the edge so as to fold the flap down against the inside surface of the wall.