| 摘要 |
<p>Method and apparatus employing radio frequency electric energy for heat sealing of laminated packaging materials (58, 60), particularly aseptic packaging materials, that include facing contiguous layers of thermoplastic material (84, 86), including first and second seal jaws (40, 56) having respective working surfaces (52, 54). The working surface (52) of the first seal jaw (40) is defined by a plurality of working faces of alternating layers of electrically conductive and electrically nonconductive materials (46, 48, 46', 48', 46''). Upon the application of RF energy across the electrically conductive layers (48, 48') of the first seal jaw (40), selective melting of the layers of thermoplastic material (84, 86) occurs, whereupon the contact pressure exerted by the seal jaws (40, 56) upon the layers of packaging material (58, 60) is assumed by the volume of nonmolten thermoplastic material disposed between the faces of the electrically nonconductive layers (46, 46', 46'') of the first seal jaw (40) and the working surface (54) of the second seal jaw (56), thereby causing the seal jaws (40, 56) to move toward each other by a limited amount by reason of deformation of the packaging material (58, 60). A seal of consistent and good uniformity is formed.</p> |
