Laser sealing of packages

1. A device for welding multiple foils to one another for use in a packaging machine, the device comprising:

a laser that provides laser radiation; and

a clamping unit configured for applying pressure to the foils in a predetermined area as well as for conducting the laser radiation used for the purpose of welding to the predetermined area;

wherein the clamping unit comprises a sealing die top and a sealing die bottom, the sealing die top and the sealing die bottom being operable to clamp multiple foils, the sealing die top and sealing die bottom defining a sealed chamber when in a closed position, wherein the sealing die top includes a non-absorbing area and wherein the clamping unit further comprises a clamping plate moveable within a portion of the sealed chamber defined by the sealing die top and operable to clamp a cover foil and a lower foil to the sealing die bottom.

2. A device according to claim 1 wherein the clamping plate includes a non-absorbing area, and wherein the laser radiation is provided as a laser beam that is conducted through the non-absorbing area of the sealing die top and the non-absorbing area of the clamping plate to the foils.

3. A device according to claim 2 wherein the non-absorbing areas of the sealing die top and the clamping plate are transparent.

4. A device according to claim 1 wherein the device fixes the foils in position all around when sealing die top and sealing die bottom are in a closed position, and spaces the foils apart within the sealed chamber while a vacuum and/or a modified atmosphere is being generated.

5. A device according to claim 1 further comprising an optical system for accurately changing the orientation of the laser radiation.

6. A device according to claim 5 wherein the optical system comprises a power-operated, x-y positioning unit.

7. A device according to claim 6 wherein the optical system changes the orientation of the laser radiation to weld the foils together along a sealing seam having a contour.

8. A device according to claim 1 wherein the device is configured for heating a sealing profile for welding the foils by means of the laser.

9. A device according to claim 1 wherein the laser is a diode laser.

10. A device according to claim 1 wherein the device comprises a sealing station.

11. A device according to claim 1 wherein the device is configured to weld a cover foil and a lower foil together at a sealing seam, and wherein the device comprises a laser for cutting through at least the cover foil outside the sealing seam.

12. A device according to claim 11 wherein the laser used for welding and the laser used for cutting are the same.

13. A device according to claim 1 wherein the device is part of a deep-drawing packaging machine or of a tray sealer.

14. The device according to claim 1 wherein at least one of the sealing die bottom and the clamping plate includes a laser absorbing section or insert.

15. A method for use in a packaging machine for welding multiple foils to one another by means of a laser in a sealing station, the method comprising:

clamping a cover foil and a lower foil between a sealing die top and a sealing die bottom, the sealing die top and sealing die bottom defining a sealed chamber;

spacing the cover foil and the lower foil apart;

evacuating and/or gas flushing the sealed chamber;

pressing the foils together between the sealing die bottom and a clamping plate disposed within a portion of the sealed chamber defined by the sealing die top, the clamping plate moveable within the sealed chamber and having an area larger than the area of a sealing seam, and

welding the foils to one another along the sealing seam by means of radiation of the laser.

16. A method according to claim 15 further comprising heating at least one of the sealing die bottom or the clamping plate by the laser radiation.

17. A method according to claim 16 wherein, during the welding operation, the laser radiation is conducted from outside of the sealed chamber through a non-absorbing area of the sealing die top to the foils or to at least one of the sealing die bottom and the clamping plate.

18. A method according to claim 15 wherein, prior to opening the sealed chamber, the cover foil and/or the lower foil is/are cut through at least partially by means of a laser.

19. A method according to claim 18 wherein the laser used for welding and the laser used to cut are the same.

20. A method according to claim 15 wherein, during the welding operation, the laser radiation is conducted through a non-absorbing area of the sealing station to the foils or the unit.

21. The method according to claim 15 wherein said welding step comprises heating a laser absorbing section or insert of at least one of the sealing die bottom or the clamping plate with the laser.

22. A device for welding multiple foils to one another for use in a packaging machine, the device comprising:

a laser that provides laser radiation; and

a clamping unit configured for applying pressure to the foils in a predetermined area as well as for conducting the laser radiation used for the purpose of welding to the predetermined area;

wherein the clamping unit comprises a non-absorbing cover plate and a sealing die bottom, the non-absorbing cover plate and the sealing die bottom being operable to clamp multiple foils, the non-absorbing cover plate and sealing die bottom defining a sealed chamber when in a closed position, wherein the clamping unit further comprises a clamping frame moveable within a portion of the sealed chamber defined by the sealing die bottom and operable to clamp a cover foil and a lower foil to the non-absorbing cover plate; and

wherein the laser is operable to weld the foils together along a continuous sealing seam.

23. The device according to claim 22 wherein the clamping frame includes a laser absorbing section or insert.