| 摘要 |
1,061,510. Seaming non-metallic sheet material. DAREX G.m.b.H. Jan. 31, 1966 [Feb. 10, 1965], No. 4223/66. Heading B5K. Apparatus for producing multipoint seals in packaging films comprises a sealing bar 2 of insulating material provided with spaced perforations 4 through which a resistance wire 6 is threaded so that spaced apart portions of the wire 6 extend on each surface of the insulating material. Preferably, the wire portions on each surface form a discontinuous straight, angled or open or closed curved line, e.g. rectangular, circular, oval or almost punctiform shapes. Several mutually offset discontinuous lines may be formed. The sealing bar may be convex in shape, Fig. 4 (not shown), springs 26 being used to maintain it in outwardly bowed shape. The insulating material of the bar 2 may be an asbestos cement strip, a temperature-resistant and possibly somewhat flexible plastic plate, a fibre fabric or a laminated fabric. The wire 6 may be made of chrome nickel having a diameter of 0À2-0À4 mm. and may be supplied via a transformer or via an impulse generator. Hard and soft polyvinyl chloride and shrinkable and non-shrinkable polyethylene and polypropylene films are specified. |
