Patent GB-706860-A (GB)
Title: Bag bottom forming device
IPC: B31B29/00
Filed: 1951-06-29
Abstract: 706,860. Making paper bags. ST. REGIS PAPER CO. June 29, 1951 [Oct. 9, 1950], No. 15510/51. Addition to 677,256. Class 94 (2) In apparatus for forming bag bottoms wherein a succession of bag tubes is carried on a conveyer, tube and opener means are provided comprising suction devices operated in timed relationship with the conveyer to open opposed sides of the tube ends and spreader means are adapted to co-operate with the opened ends whilst in motion to form and fold the bag bottoms to shape. Tube end openers.-Flattened tubes are fed to a conveyer and carried forward in succession towards the end-opening mechanism by grippers 21, 22, Fig. 2, incisions 29 and folds 30 being formed and the ends 28a, 28b bent up in the meantime. The mechanism for opening a tube end comprises a pair of suction cups 33, 34, each carried by an endless conveyer 35, 36, Fig. 7, so arranged relatively that the opposed sides of the bag end are separated during motion. The conveyers also are inclined downwardly in the direction of suction so that the cups retain their position on the sides during the opening suction. Each cup conveyer carries two cups positioned so as to operate succeeding tubes. Fig. 6 shows the driving arrangements for the cup conveyers. The cups 33, 34 are carried by the chains 35, 36 which are driven by sprockets from the shafts 43, 44 driven through gearing 74, 75 from a shaft 65 driven from the main conveyer motor. The suction pipes 54,55 for the cups are supported from parts 56, 86 also rotatable through gearing 78 79, 87 from the same drive. The cups are pivotally mounted on arms 48, 49, and carry cam rollers 59, 60 which co-operate with guide rails 61, 62 longitudinally arranged beneath the chains 35, 36 so as to effect tilting of the cups at the appropriate times and thereby cause opening of the bag ends. The relationship between the position of the cups and the bag conveyers may be adjusted by a differential mechanism on the drive of the shaft 65, Bag end spreader mechanism.-After the bag end is opened, spreader unit is inserted into the end, Fig. 2e, and expanded to produce corner flaps 131,132. Fig. 2f. The unit is then released and withdrawn and the bag passed forward to be pasted and pressed. A number of spreader units each consisting of the mechanism shown in Fig 13, is carried on a pair of endless conveyer chains 92, 93, each unit being secured to the chains at diagonally opposite points 105, 106. and mounted on rollers which run along guide rails 109, 110. The driving wheels for the conveyers are arranged at the ends of the conveyers and each conveyer is displaced relatively to the other in the direction of run by the width of the spreader unit; the arrangement being such that when the unit reaches the end of the run on top of the conveyer it is lowered and then returned on the bottom run and vice versa whilst still maintaining the unit in a horizontal attitude. The flap forming operation is initiated during the lowering of the unit and release and withdrawal is effected when raised at the other end of the conveyer. Each unit comprises a pair of curved resilient spreader plates 138, 139 having flap forming and shaping ends 138c, 139c, the other extremities being upright and located in guide members 126, 127. The guide members are adjustable on supporting posts 118, 119, 146 so that the spreader plates 138, 139 may be accommodated to different sizes of bags. The top of the unit carries a resiliently mounted roller 145 which during the bottom run of the conveyer co-operates with a V-shaped channel guide 144a, 144b, 144c, Fig. 9, to firstly force the spreader plates 138, 139 in opposite directions and then withdraw them, thus completing the flap forming operation and allowing withdrawal of the unit from the bag end. The angularity of the V-shaped guide is adjustable by gear mechanism 155.