| 摘要 |
<p>The neck of a container of thermoplastic material, through which it has been filled, is flattened in the zone in which it is desired to make a welded joint. The flattening is effected so as to form two walls facing each other, jointed by two folds aligned at right angles to the proposed seam. The two walls are pressed together and relative, alternating motion between them is generated, whilst the pressure is maintained, for pref. at right angles to the direction of the neck. This heats up the zone of contact and causes a localised melting together. The relative motion is interrupted and the welding of the zones takes place during cooling. Used for sealing containers of thermoplastic material into which goods have been tipped in small or large quantities for conditioning under vacuum. Arrangement overcomes the difficulties arising from the need to control the degree of flow on the two faces brought together, which is further complicated by irregularities in thickness of the film.</p> |
