Patent ID: 8151851

Claim:
Welding apparatus for use in one-step welding to form a bag assembly comprising a bag and a tube in fluid communication with the bag, the welding apparatus comprising: first and second die members opposing one another and defining a space therebetween for receiving opposing sheets and a tube therebetween, the first and second die members including opposing respective first and second perimeter-welding electrodes adapted to weld the sheets together to define a perimeter-weld of the bag and opposing respective first and second tube-welding electrodes adapted to weld the sheets to the tube to define a tube-weld so that the tube is in fluid communication with the bag; a single source of high frequency energy electrically connected to the first and second perimeter-welding electrodes and the first and second tube-welding electrodes to produce a high frequency electric field between the perimeter-welding electrodes and the tube-welding electrodes; and dielectric material for reducing the strength of the high frequency electric field between the first and second perimeter-welding electrodes as compared to a strength of the high frequency electric field between the first and second tube-welding electrodes so that the sheets are welded to the tube and the sheets are welded together in a single welding operation; wherein the first and second tube-welding electrodes each have a circumferential-welding surface and opposite lateral-welding surfaces, and wherein a second dielectric material is provided having a selected thickness and a selected dielectric constant for reducing the strength of the high frequency electric field between the lateral-welding surfaces of the tube-welding electrodes as compared to the strength of the high frequency field between the circumferential-welding surfaces so that lateral-weld areas of the sheets are welded at generally the same rate as the tube and the sheets are welded together.