GB882222A - Improvements in or relating to machines for making paper and like bags - Google Patents

Abstract

882,222. Forming bag tubes. STRACHAN & HENSHAW Ltd. Sept. 2, 1960 [June 3, 1959], No. 19010/59. Class 94(2). Relates to tube-forming apparatus wherein a web of paper is folded about a former plate to form a tube and is forwarded to a cut-off position and consists in a nip-bar assembly comprising an upper and a lower roller 22, 23 with nip-bars or lands 26, 27 respectively, the roller being angularly adjustable relatively to each other to vary the peripheral lengths of contact of the lands which co-operate with each other to nip the paper tube after it has issued from the former plate. The land extends for substantially the full length of its roller and, in the embodiment shown, subtends an angle of approximately 60 degrees. The peripheral speed of the rollers is less than the travelling speed of the tube as imparted by rollers 14, 15 and when the tube is nipped between the lands a slack 28 is therefore caused in it of an amount governed by the length of contact of the lands, which may be varied between a maximum of 60 degrees of rotation of the rollers 22, 23 and a minimum of the smallest fraction of a degree which will produce practically only a line nip of the tube. A heater bar 20 rotates so that it moves upwards from below the paper tube in a path 21 slightly in advance of the forward edge 17 of the former plate 11 and forces the lower ply 13 against that edge and the upper ply 12 against the edge 19 of a breaker plate 18, both edges being serrated. The tube is then cut with the edges of the plies one in advance of the other, which facilitates the sealing of the end of the tube to form a bag. The slack 28 assists the cutting action and the relative angular adjustment of the rollers 22, 23 allows the correct amount of slack whether the tube is moving slowly, for a long bag, or quickly, for a short bag.