Apparatus and method for applying cover sheets to ends, preformed into cross bottoms, of tube portions

A method for applying cover sheets to ends of tubular sections made of a plastic material, the ends having been preformed into cross-bottoms, wherein the ends preformed into cross-bottoms each have a first outer triangular area, a first inner triangular area, a second outer triangular area, a second inner triangular area and a central area, wherein, in a longitudinal bottom direction, the first inner triangular area is arranged between the first outer triangular area and the central area, and the second inner triangular area is arranged between the second outer triangular area and the central area, the method comprising operations of:

• a) transporting the tubular sections in a conveying direction, the longitudinal bottom direction of the cross-bottoms being in parallel to the conveying direction;
• b) transporting the cover sheets in the conveying direction;
• c) while the tubular sections are being conveyed, always placing one cover sheet on a cross-bottom in a deposit area, when one of the cross-bottoms passes the deposit area,
• wherein the method furthermore comprises supplying a gas with a mass flow ({dot over (m)}ges) to a hot gas device while the cover sheet is being applied, the hot gas device comprising a gas heater, a hot gas reservoir and a nozzle which configured to direct heated gas into the deposit area, and
• wherein:
• the gas is supplied to the hot gas device with an increased mass flow ({dot over (m)}ges), while the first inner triangular area of a cross-bottom passes the deposit area;
• the gas is supplied to the hot gas device with a reduced mass flow ({dot over (m)}1), while the central area of a cross-bottom passes the deposit area;
• and
• the gas is supplied to the hot gas device with an increased mass flow ({dot over (m)}ges), while the second inner triangular area of a cross-bottom passes the deposit area.