Pulse welding method and welding tool for pulse welding for a medical pack formed as a bag
AssigneeFresenius Kabi Deutschland GmbH
InventorsGerald Wegner, Jorn Wittorf
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Abstract
The invention relates to a welding tool and a method for pulse welding films of plastic for medical packs formed as bags. The invention generally provides for the film material that has been plastified during welding, and is consequently free-flowing, to be specifically displaced by increasing the sealing surface area. The displaced film material can for instance compensate for dimensional and form tolerances. At the same time, however, the strength of the welded seam region, which adjoins the interior space of the bag, is not reduced.
Claims18
A welding tool for pulse welding a plastic film of a medical pack, said welding tool comprising a welding jaw having a sealing strip for clamping the film during welding thereof,
- wherein the sealing strip extends along the welding jaw and can be pressed onto the film,
- wherein the sealing strip comprises a sealing surface and inner and outer clamping regions that adjoin the sealing surface,
- wherein the sealing strip can be heated to plasticize that portion of the plastic film that adjoins the sealing surface, thereby forming a weld seam, and
- wherein the sealing surface comprises
- a plateau that protrudes from the sealing strip
- an inner peripheral region that extends between the plateau and the inner clamping region, and
- an outer peripheral region that extends between the plateau and the outer clamping region,
- wherein the inner and outer peripheral regions are depressed relative to the plateau,
- wherein, during welding, the inner and outer peripheral regions form closed cavities that are disposed between the plateau and the clamping regions and that receive plasticized plastic material that has been displaced as a result of film above said plateau having been melted.
A pulse welding method comprising using a welding tool for pulse welding a plastic film of a medical pack, wherein the welding tool comprises a welding jaw having a sealing strip for clamping the film during welding thereof, wherein the sealing strip extends along the welding jaw and can be pressed onto the film, wherein the sealing strip comprises a sealing surface and inner and outer clamping regions that adjoin the sealing surface, wherein the sealing strip can be heated to plasticize that portion of the plastic film that adjoins the sealing surface, thereby forming a weld seam, wherein the sealing surface comprises a plateau that protrudes from the sealing strip, an inner peripheral region that extends between the plateau and the inner clamping region, and an outer peripheral region that extends between the plateau and the outer clamping region, wherein the inner and outer peripheral regions are depressed relative to the plateau, wherein, during welding, the inner and outer peripheral regions form closed cavities that are disposed between the plateau and the clamping regions and that receive plasticized plastic material that has been displaced as a result of film above said plateau having been melted, said method comprising compensating for shape and dimensional tolerances, wherein compensating for the shape and dimensional tolerances comprises
- pressing the welding jaw of the welding tool to form a weld seam onto the film,
- clamping the film peripherally to form the closed cavities,
- maintaining the clamping region at a temperature that is cooler than the sealing surface, and
- causing the plateau to displace plasticized plastic material of the film at least laterally along the weld seam, thereby compensating for the shape and dimensional tolerances, and
- maintaining film thickness in an inner peripheral region of the weld seam.
Dependencies are inferred from the claim text.