Patent ID: 7681496

Claim:
A strapping device to strap/loop materials to be packaged by means of packing strap ( 44 ) fitted with a protective layer ( 44 c ), said strapping device comprising: a sealing system to connect and seal to each other two superposed strap plies ( 44 a , 44 b ) of a loop of the packing strap, wherein the sealing system is a resistance welder fitted with at least two electrode members ( 35 a , 35 b ; 36 a , 36 b ) connected to a power source and at least one piercing portion for piercing the packing strap protective layer ( 44 c ) at one of the strap plies ( 44 a , 44 b ), the at least one piercing portion is a clamp element located adjacent to one of the at least two electrode members, wherein a preheating current of the resistance welder is applied to the packing strap fitted with the protective layer to lower an electrical resistance between the two superposed strap plies, wherein a welding current of the resistance welder which is substantially higher than the preheating current, is thereafter applied to the two superposed strap plies to connect/seal the two superposed strap plies, and wherein the clamp element provides an electrical path for the preheating element that is different from an electrical path followed by the welding current.