| 摘要 |
<p>Two areas of thermoplastic- surfaced sheet material are heat-sealed by a reciprocable sealing jaw 13 and, as the jaw is retracted from the sheet material, a fluid medium is directed between the jaw and the adjacent sheet material to prevent the material following the return movement of the jaw. The jaw 13 may comprise two parallel heatable electrical resistance strips 15 and two fluid discharge holes 16 through which air or cooling water is continuously or intermittently supplied. Internal cooling ducts may be provided. In a form-fill-seal packaging machine, for forming a transverse seal, the jaw cooperates with a center-jaw either of the same type or non-heatable, and which may have a rubber working surface. A cutting knife may be recessed in a non-heatable counter-jaw. <IMAGE></p> |
