Patent GB-1292821-A (GB)
Title: Improvements in and relating to a container forming machine
IPC: B31B3/32
Filed: 1969-10-15
Abstract: 1292821 Making gable top cartons TETRA PAK INTERNATIONAL AB 15 Oct 1969 [30 Oct 1968] 50741/69 Heading B5D [Also in Division B8] A machine capable of making cartons of two different sizes comprises an intermittently rotatable mandrel wheel 6 carrying two sets of mandrels 5 and 5<SP>1</SP> of different cross-sectional areas for receiving open-ended tubular blanks of polythene coated material. Arranged at indexing stops of the mandrel wheel 6 are a prefolder 7 for prefolding the bottoms, a hot air heater 8 and a pressure plate 10 for forming the carton bottoms after they have been folded by a plough (36, Fig. 1) extending anticlockwise from the heater 8. A suction gripper 11 transfers cartons 33 from the mandrels to a conveyer which intermittently moves the cartons 33 to another prefolder 14 for prefolding the tops of the cartons, and expander 15 and a filling unit 16, past stationary folding rods (114, Fig. 1) to a heating unit 17 and two compression blocks 18. The mandrel wheel rotates in steps of 360 degrees/n (where n is the number of mandrels in each set) and to change over from one set of mandrels to the other a single incremental rotation of 360 degrees/2n is carried out. In order to take up the stress exerted on the shaft of the mandrel wheel 6 by the pressure plate 10 a semicircular yoke 85, Fig. 5, placed around the shaft 54 of the mandrel wheel 6 is connected to a pneumatic cylinder 29, that operates the pressure plate 10, by rods 84. The pneumatic cylinder 29 and the rods 84 are resiliently mounted on the frame of the machine by rubber elements 87. The mandrel wheel 6 is connected to its driving shaft 54, Fig. 3, by connectors 65 which rotate with the shaft 54 and rest in connector seats 67 of a ring 63 connected to the hub 56 of the mandrel wheel 6. These connectors 65 are located in slots 66 in a disc 72 which is secured to the head 62 of the driving shaft 54, and are pressed into the connector seats 67 by a pressure plate 73; such an arrangement allows the mandrel wheel 6 to become disengaged from the driving shaft in the event of the mandrel wheel becoming overloaded. Two sets of connector seats 67 having an angular displacement of 30 degrees relative to each other to allow the change-over from one set of mandrels 5 or 5<SP>1</SP> to the other. When the mandrel wheel 6 is overloaded the pressure plate 73 is pushed by the connectors 65 away from the disc 72 and this movement is detected by a micro-interruptor or an air valve which actuates a pneumatic cylinder (70, Fig. 4) to cause a lever (71) to move the pressure plate 73 further away from the disc 72. The suction gripper 11 comprises a suction cup (37, Fig. 6) mounted on a pusher-rod (74) and connected through a valve (76) to a vacuumsource, the ambient atmosphere or alternatively a compressed air source. This valve is indirectly operated by the movements of the push-rod (74) through a unit (101) and adjustable vertically relative to the carton track 12 so that each carton is released by the suction cup (37) at the same time as, or immediately before, the carton contacts the track 12. The carton blank is pressed out from a sheet of polythene coated cardboard, provided with fold lines (103, Fig. 7) and its two longitudinal edges united in a longitudinal joint (104). The bottom end (35) of the carton blank (4) has two large rectangular flaps (105 and 106) and two smaller triangular areas (107 and 108) joined to the larger flaps (105, 106) through fold-back flaps (109 and 110). The top portion (113) of the carton blank is similar to the bottom end (35) although the dimensions of the various areas are different and sealing areas (112) which are designed to be brought together to form a flat fin are provided.