Patent ID: 7344616

Claim:
Method of welding two container walls of plastic film ( 1 , 2 ) on to a plastic tube ( 3 ) having a substantially circular cross-section, wherein the plastic tube ( 3 ) is arranged between two parallelly arranged plastic films ( 1 , 2 ), the two plastic films ( 1 , 2 ) being made to extend along the outer surface of the plastic tube ( 3 ) and to abut each other along a joint face ( 7 ) between two welding jaws ( 5 , 6 ) in an area ( 8 ) adjoining the plastic tube ( 3 ), and wherein the plastic films ( 1 , 2 ) are welded by means of the welding jaws ( 5 , 6 ) on to the outer face of the plastic tube ( 3 ) and welded together in the area ( 8 ) adjoining the plastic tube ( 3 ), wherein the plastic tube ( 3 ) is elastically deformed during welding by means of a compressive force applied by the welding jaws ( 5 , 6 ) to provide the outer face of the plastic tube ( 3 ) with two diametrically opposed plane portions ( 9 ) which each extends on both sides of the joint face ( 7 ) and substantially perpendicular thereto, where two welding jaws ( 5 , 6 ) are used, which are adapted to enclose the plastic tube ( 3 ) and the plastic films ( 1 , 2 ) when closed, in a cross-sectional view each welding jaw ( 5 , 6 ) having a curved welding area ( 11 ), characterised in that in a cross-sectional view each welding jaw ( 5 , 6 ) having a substantially linear welding portion ( 10 ) extending substantially perpendicular to the joint face ( 7 ) between the joint face ( 7 ) and each end of the curved welding area ( 11 ).