| 摘要 |
The present invention relates to a method and an apparatus in ultrasonic sealing of a tubular packaging material of non fibre multilayer structure displaying an overlap joint extending along the longitudinal direction of the tubular packaging material. The method entails that an ultrasonic horn with an elongate primary contact surface and an anvil with an elongate primary contact surface, these primary contact surfaces being disposed for cooperating transverse primary sealing of a tubular packaging material clamped between them, in a first step by means of the primary contact surfaces abut the material along a first elongate active primary contact surface, and that, in a second step, after a predetermined penetration into the packaging material has been achieved, the active primary contact surface is widened increasing the area cooperating for primary sealing on further penetration. The apparatus includes an ultrasonic horn with an elongate primary contact surface (3) and an anvil with an elongate primary contact surface (4) intended to cooperate with the primary contact surface of the ultrasonic horn for transverse primary sealing of a tubular packaging material (1) clamped between them, the actively cooperating primary contact surfaces (3, 4) in primary sealing displaying at least two levels of active primary contact surfaces (4.1, 4:2, 4:3) disposed, on abutment of the tubular packaging material, to enter into operative engagement in sequence, and the first abutting level (4:1) displaying a constant height throughout its entire extent, the level difference between the first abutting level (4:1) and the last abutting level (4:3) being less than the thickness (t) of the packaging material. |
