Device and method for top seal packaging

A top-seal wrapping device arranged to cover a top opening of a tray containing a wrapping target with a stretch film, and to weld the stretch film to a peripheral portion of the tray around the opening while thermally cutting the stretch film, comprising:

• a stretch mechanism arranged to stretch the stretch film;
• welding means for welding the stretch film to the peripheral portion of the tray;
• control means operatively coupled to said stretch mechanism for controlling the stretching of the stretch film by operating said stretch mechanism at least before said welding means welds the stretch film to the tray;
• cutting means for thermally cutting the stretch film at a cut portion;
• a heating body arranged to contact the peripheral portion of the tray surrounding the opening and contact the stretch film for welding the stretch film to the peripheral portion of the tray around the opening;
• a film winding portion arranged to wind up the stretch film after said cutting means cuts the stretch film,
• a film transporting mechanism arranged to transport the stretch film;
• and
• a lift mechanism arranged to lift the tray such that the tray is pushed against the film that is transported by said film transporting mechanism
• said control means controlling said stretch mechanism to stretch the stretch film before the tray contacts the stretch film, and further controlling said stretch mechanism to reduce tension of the stretch film after the tray contacts the stretch film and before the stretch film is welded to the tray.

A top-seal wrapping method for covering a top opening of a tray containing a wrapping target with a stretch film, welding the stretch film to a peripheral portion of the tray around the opening and thermally cutting the stretch film, comprising steps of:

• supplying a film by transporting the stretch film in a transporting direction to a position above the tray;
• welding the stretch film to the peripheral portion of the tray;
• stretching the stretch film in a direction crossing a direction in which the stretch film is transported at least before welding the stretch film to the tray;
• cutting the stretch film thermally at a cut portion;
• winding the remaining stretch film after the thermal cutting;
• and
• controllably stretching the remaining stretch film in a direction perpendicular to a direction in which the stretch film is wound up.