发明名称 Method and apparatus for manufacturing sacks.
摘要 A method and apparatus are described for manufacturing cushion-shaped and/or bellows-shaped sacks, made of polyethylene or other heat-sealable material, obtained by superposing two films or sheets which are unwound from respective rolls and are submitted to a pair of longitudinal sealings to form the tube to be filled, and to a pair of transverse seals and an intermediate cut for closing, at the front and rear ends, the sacks obtained from said tube. According to the invention, the edges of at least one of said sheets are formed with at least one respective re-entrant fold (P2-P2 min ) whereby said edges will overlap, with a portion of their outer faces, corresponding portions of the inner face of the other sheet, or vice versa. When only one of said sheets is folded at the edges, the sealing of the overlapped end portions is effected by a single respective sealing bar (15-15 min ) acting on the outer face of the edges to be joined and having an opposite cold and possibly stationary contrasting member (16-16 min ). In order to concentrate the sealing heat only on the edge portions to be secured to each other, and to prevent said heat from reaching the sheet whose edges (P2-P2 min ) have been folded and acted upon by said stationary contrasting member (16-16 min ), preferably a strip of any suitable material, sufficiently flexible and of such a length as to co-extend with said sheets over the entire extent of the sealing bars, operates between the parts of said edge portions. As an alternative, both sheets are folded at their edges, and in this instance a double sealing can be effected on the superposed edges by pairs of sealing bars (15-115-15 min -115 min ).
申请公布号 EP0397099(A1) 申请公布日期 1990.11.14
申请号 EP19900108626 申请日期 1990.05.08
申请人 B.L. MACCHINE AUTOMATICHE S.P.A. 发明人 VETTORATO, NATALE
分类号 B31B19/36;B31B23/00 主分类号 B31B19/36
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