Apparatus for making bag assembly

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, 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, the first perimeter-welding electrode and first tube-welding electrode defining a first welding surface, and the second perimeter-welding electrode and second tube-welding electrode defining a second welding surface opposing the first welding surface;
• a single source of high frequency energy electrically connected to the first and second perimeter-welding electrodes and to 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 selectively disposed on the first welding surface such that the material is disposed on some but not all the first welding surface 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 at least a portion of 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.