Patent GB-947746-A (GB)
Title: Rotary drum machines for making block-bottom bags
IPC: B31B29/00
Filed: 1962-05-29
Abstract: 947,746. Making block-bottom bags. BEMIS BRO. BAG CO. May 29, 1962 [May 29, 1961], No. 20590/62. Heading B5D. [Also in Divisions B2 and B8] While one pair of folds x (Fig. 23) of the gussets of a tubular blank T are held by grippers 7 on a drum rotating continuously on its shaft 21 (Fig. 4), the other folds y (Fig. 23) are turned back to the position of Fig. 24 by grippers 9 (Fig. 4) which turn on pivots 93 (Fig. 11) on the drum against the direction of rotation. Both sets of grippers 7, 9 are moved laterally into engagement with the gussets and, after they have gripped, are biased laterally outwards to stretch the flaps A, B (Fig. 23); the grippers 9 are also biased against the direction of rotation of the drum to stretch the side flaps C (Fig. 23). In the machine illustrated the side flaps C are subsequently turned in, and the flaps B, A pasted and turned over, to form the block-bottom shown incomplete in Fig. 26, as the tubular blanks are carried on the drum which finally delivers the ram to opposed conveying bands 609, 613 (Fig. 5). Opening tube-end A, B (Fig. 23).-As the tube blanks are fed by a pusher conveyer 11 (Fig. 5) towards the drum the leading ends, which have previously been slit at S (Fig. 23), are opened by pneumatic cups 281 (Fig. 5) carried on rotating arms 279. The leading gussets are then held open by guides 293, 295. The three sets of grippers 7, 9 carried by the drum of the machine illustrated are moved laterally inwardly to engage the opened gussets by levers 171 (Fig. 4) turned about pivots 173 on the drum by fixed cams 203R, 203L, 205R, 205L, engaging rollers 199, 201 on the levers. After the grippers have seized the gussets the levers 171 are turned sufficiently to cause springs 195 to pull the grippers outwardly to stretch the flaps A, B (Fig. 23). The jaws of the grippers are closed by pneumatic cylinders supplied with pressure air under the control of valves 155 (Fig. 5) carried by the drum and operated by cam surfaces 165. The grippers 9 are turned about their pivots 93 (Fig. 11) on the drum 1 by a gear 127 meshing with a sector 129 turned about a shaft 133 by an arm 147 (Fig. 5) carrying a roller 149 engaging a fixed cam 151. A spring 139 (Fig. 11) is interposed between the arm 147 and the sector 129. The jaws 115 of the gripper 9 are carried on the body of the gripper by a pivot 105 and are biased by a spring 118 so that, when the grippers 9 have been rotated about their pivots 93, the spring 118 applies tension to the side flaps C (Fig. 23). A pivoted creasing blade 305 (Fig. 5) defines the line D (Fig. 25) about which the flap B is folded. Folding in side-flaps C (Figs. 23 and 24).-A ball-ended plunger 329 (Fig. 5) holds down the flap B while reciprocating folders 321 (Fig. 13) fold in the side-flaps C. Pasting.-A pasting wheel 359 (Fig. 5), for applying the paste stripes P shown in Fig. 24 is lifted out of engagement with the drum 1 whenever a feeler (not shown) detects the absence of a blank on the drum. The pasting wheel 359 carries a cam 375 (Fig. 15) which normally acts through a roller 377 to depress a lever 379 about its pivot 381 against the bias of a spring 383. When however a solenoid 393 is operated by the feeler it holds a latch 385 in position to look the lever 379 so that the cam 375 serves to raise the pasting wheel 359. Folding flap B (Figs. 24 and 26).-The flap B is folded by blades 403 (Fig. 16) about a line D defined by the end of a creasing blade 401. The folding blades 403 are pivoted at 455 to an oscillating arm 457 and controlled by cams 485, 487, 477 to engage under the flap B, while it is in the position of Fig. 24, and then to raise it, push it about the creasing blade 401, and then press down upon it. The creasing blade 401 describes a closed curve under the control of cams 437, 439, 451. Folding flap A (Fig. 26).-The flap A is folded about a creasing blade 525 (Fig. 17) by blades 559 controlled by a cam (not shown) which provides a rapid movement of the blades from the position shown in broken lines in Fig. 17 to that shown in full lines. During these operations the folded flap B is held down by a shoe 507 operated by a pivoted hydraulic cylinder 503. The bags are subsequently carried under a rubber roller 601 pressed against the drum by a spring 607. Adjustments.-To permit operation on tubes of different widths the grippers 7, 9 are carried by spiders 37 (Fig. 4) which can be adjusted axially and angularly on the shaft 21. The jaws 9 can be adjusted on their shafts 93 (Fig. 11), and the guides 293, 295 (Fig. 5) can be adjusted laterally, as also can the various folding and creasing blades.