Patent GB-621049-A (GB)
Title: Method and means for opening bags
IPC: B65B43/34
Filed: 1946-05-02
Abstract: 621,049. Opening and distending bags. BETNER CO., B.C. May 2, 1946, No. 13309. Convention date, Aug. 8, 1945. [Class 94(i) [Also in Group XXX] A method of expanding gussetted bags of the square type from the flattened condition comprises opening the mouth of the bag and thereafter progressively expanding the body of the bag from the mouth to the bottom while restraining the bag walls in mutually rectangular relationship, initiating fold lines for the bag bottom by pneumatic pressure exerted within the bag concomitantly with the progressive expansion of the bag body and then completing the bag bottom by creasing the material of the bag along the initiated fold lines by positive compression. Bag magazine 110, Figs. 6 and 7, contains a supply of bags in the channel defined by guide plates 128 and brackets 114 the bags being pressed against fingers 154, 160, 172 by a moveable plate 130 which is connected to a freely hanging weight 142 by a chain 136 which passes over pulleys 138 and 140 A suction head 100, Fig. 1 is mounted on rods 102 and reciprocates horizontally, the foremost bag in the magazine is engaged by suction head 100 which moves backwards drawing with it the front wall 200 of the bag, Fig. 16, slipping the front wall and bottom 208 past the fingers 154 and 160. Fingers 160 then engage the rear wall 204 of the bag and fingers 172 remain in engagement with the lip 210, thus opening the mouth of the bag. Mounted on the forward end of the bag magazine is a pair of members 300, Figs. 6, 7 and 16. Each member is mounted to rock about an axis 302, a spring 304 tending to maintain the member in a horizontal position. When the foremost bag in the magazine is in the partially opened position shown in Fig. 16 any downward pressure on members 300, between their ends 300<SP>1</SP> and their axes 300 will tend to rock the members into a vertical position in which they enter the bag mouth giving it a rectangular configuration. A plunger 26, Fig. 1, dimensioned to fit closely the interior of the bag body, is connected by a bracket 24 to an elevator member 22 which reciprocates in a vertical passageway defined by guides 20. Movements of the suction head 100 and the plunger 26 are so synchronised that the descending plunger enters the partially opened mouth of a bag and forces down members 300 into the mouth to form it into a rectangular shape. The closeness of fit between plunger and bag ensures a substantial static pressure between the plunger nose and the bottom of the bag, augmented by a jet of air from the nose of the plunger, which expands the bag and initiates the fold lines of the bag bottom. Cartons are advanced on a conveyor (see Group XXX) mounted on platform 50, the intermittent movements of the conveyer being synchronised with the movements of the plunger to present a carton below the plunger at each of its downward movements. An opened bag is stripped by the plunger from the fingers 160, 172 and suction head 100 and is inserted in the carton, continued air pressure through the nose of the plunger stripping the bag from the plunger as the plunger ascends. A valve 600, Figs. 13 and 14, has a connection 602 to suction head 100 and a connection 604 to the suction side of air pump 606. The valve comprises a member 608, slidably mounted in a cylinder 610, and urged downwards by a spring 620. Before the suction head engages a bag wall a switch 652 is closed by a carton advancing on the conveyer. Solenoid 636 is energised, armature 634 is drawn downwards and member 608 is forced upwards by bell crank 628, thus covering port 616 and permitting suction to be applied to the suction head, this suction being sufficient to maintain member 608 in its uppermost position against the action of spring 620 when the suction head engages a bag wall. When the descending plunger strips the bag from the suction head, suction is broken, the spring 620 forces member 608 down uncovering port 616 and permitting a free flow of air through the pump 606 via pipe 28 to the nose of the plunger. A motor 400, Fig. 1, drives the pump 606 and, through gears 406, 412, 408, 418, a cam shaft 416. A follower 432 on bell crank 428 engages a cam on shaft 416 and controls, through rod 434, the horizontal oscillations of the suction head. Lever 450 is moved by follower 454 engaging cam 426 and operates, through gear segment 456, gears 458, 464, and 468 and rack 470, the elevator 22 and plunger 26.