| 摘要 |
<p>The apparatus has an upper sealing arrangement comprising two sets of heat sealing bars (10, 11) and their support (12, 13), and a lower sealing arrangement comprising lower sealing bars (15, 16) and their support (17, 18). The lower sealing bars operate at a lower temperature than the upper sealing bars so as to seal only the inner layers of a bag together whereas the upper sealing bars can heat seal both the inner and outer layers of the bag together. An overlying protective sheet (20) of PTFE protects the heads (10, 11, 15, 16), and prevents any adherence to the neck of the bag. Perforation means (30) having a perforation bar (31) with a saw-tooth like series of projections along one edge is positioned between the upper and lower sealing bars.</p> |
