Arrangement for continuous induction welding
AssigneeTetra Pak Holdings & Finance S.A.
InventorGert Holmstrom
Life of this patent
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Abstract
The invention relates to an inductive heating apparatus for carrying out a continuous weld along a moving web of laminated packing material (8). The apparatus includes two similar elongated metal plates (1) with two slots (2, 12). The metal plates (1) are arranged at some distance from one another and are connected electrically to one another and to an a.c. source (10). The laminated packing material (8) which is to be welded together is advanced between the two plates (1). Within the plates (1), pressure rollers (6) are arranged in a recess (5).
Claims24
An apparatus for the continuous induction welding along a moving web of laminated packing material including a metal layer and surface coatings of thermoplastic material, comprising:
- an inductor including a plurality of plates;
- means for supplying current to said inductor;
- a first slot in each of said inductor plates extending substantially along the length of said inductor plates and located asymmetrically with respect to the width of said plates;
- and
- a second slot in each of said inductor plates connecting said first slot to an outer edge of said plates.
An apparatus for the continuous welding of a moving web of laminated packing material, comprising:
- a first conductive plate including a first longitudinal slot extending substantially along the length of said plate and dividing said first plate into first and second conductors;
- a second conductive plate including a second longitudinal slot extending substantially along the length of said second plate and dividing said second plate into third and fourth conductors,
- an AC current source;
- and
- means for connecting said AC power source to said first and fourth conductors, said first, second, third, and fourth conductors being sequentially connected in series,
- said first and second plates being oriented to align said first and second longitudinal slots and said first and third conductors having a lesser resistance than said second and fourth conductors, whereby packing material moving between said first and second plates is welded between said second and fourth conductors.
An apparatus for continuous induction welding along a moving web of laminated packing material including a metal layer and surface coatings of thermoplastic material, comprising:
- an inductor having two parallel, conductive plates of uniform thickness, each plate including a longitudinal slot extending substantially along the length of each plate and located asymmetrically with respect to the width of said plates to form a narrow conductor and a wide conductor, said wide conductor being three times as wide as said narrow conductor and having a greater conductivity than said narrow conductor, and a transverse slot connecting said first slot to an outer edge of each plate, wherein said longitudinal and transverse slots of each plate are aligned;
- an AC power source;
- means for electrically connecting said power source in series with said conductive plates, wherein packing material moving between said two plates is sufficiently heated between said narrow portions of each plate to weld an edge of said packing material and said packing material moving between said wide portions of each plate is only minimally heated.
Dependencies are inferred from the claim text.