| 摘要 |
Plastic, esp. polyethylene, tube is transversely seam-welded at intervals to form bags, or linings for paper bags. Foil is passed continuously around a revolving drum-type rotor, being pressed against drum around part of the periphery by an endless belt. Drum carries radially adjustable welding heads running parallel to axis, pref. each comprising two welding blades with a perforator between them. |
