An apparatus for forming containers fed with their side walls arranged in a flattened tubular configuration, comprising a device for opening the containers that is associated with abutment-retention elements for the abutment and retention of the containers in the open configuration and with transfer elements for transferring the open containers into respective variable-geometry receptacles of a conveyance line, the receptacles being suitable to move from a first open configuration for receiving the containers to a second closed configuration for conveying the containers to a subsequent treatment station.

A carton opening mechanism for use in opening knocked-down cartons has a carton storage magazine which has a discharge opening. The mechanism has a first suction face which is circumferentially spaced 120 degrees from the discharge opening of the magazine. The mechanism is mountable so as to locate the receiver compartment equidistant from the discharge opening and first suction face. A rotary transfer mechanism is mounted for rotation about the central axis and has a suction head formed with a transfer suction face. The transfer suction face is moves between, a first position in which it is directed toward the discharge opening and positioned to engage a wall of a carton blank located in the storage magazine and, a second position in which it is directed toward and disposed opposite the first suction face of a carton opening mechanism to press an opposite wall of the carton into engagement with the first suction face, and, a third position in which it is directed toward and disposed adjacent the entranceway of the receiver to deposit an open carton in a receiver compartment. The transfer mechanism then returns to the first position. A suction control mechanism is provided to generate a negative pressure at said transfer suction face when it is required.