Patent GB-1137057-A (GB)
Title: Machine for the automatic controlled manufacture and output of plastics bags
IPC: B31B19/10
Filed: 1966-02-22
Abstract: 1,137,057. Making bags; seaming non- metallic sheet material. CENTRA ANSTALT. 22 Feb., 1966 [22 Feb., 1965; 20 Nov., 1965], No. 7662/66. Headings B5D and B5K. [Also in Divisions B8 and F2] Apparatus by which bags are made from a tubular web 2 of thermoplastic material comprises means for intermittently feeding and cutting the required length of material, and for sealing and delivering the bags. Drive.-In the embodiment shown a continuously rotating shaft 9 transmits the drive to a disc 10 carrying a pivot 11 eccentrically and adjustably mounted in a diametral slot in the disc 10 and connected through a link 12 and chain 12<SP>1</SP> to a roller 28. In an alternative embodiment, the drive is transmitted from the disc (10), Fig. 11 (not shown), by a rack (12) pivoted to the disc (10) at a point (11). A clutch, Figs. 12, 13 (not shown), connected to the roller 28, Fig. 1, is automatically engaged and disengaged to permit rotation in the forward direction only. A shaft coaxial with the roller 28 transmits the intermittent drive to the remaining parts of the machine. Cutting.-The tube 2 is drawn from a roll 1 through a flattening guide 5 by rollers 13-15 and is cut into suitable lengths by blades 18, 19 which may operate on a guillotine principle. The length of web drawn each time may be adjusted. The moving blade (18), Fig. 5 (not shown), which is preferably pivoted, is urged downwards by a spring (84) towards the fixed blade (19), the timing of the operation being controlled by a cam (81). Punches (20) may be provided to print on the web at this stage. The web may alternatively be cut by a sliding blade (100), Fig. 23 (not shown), mounted in an arm (105) driven, through a lever (101), by a cam (102). In this case a further cam (107) is provided to lift the blade (100) clear of the web on the return stroke of the blade. Forming the bag bottom.-The cut length of tube is fed by a conveyer 22, Fig. 1, between drums 25, 27 at one end of parallel conveyers 23, 24. Heated jaws 29, 30 controlled by thermocouples (71, 72), Fig. 9 (not shown), and operated by a cam (68) then seal the end of the length of tube which is to form the bottom of the bag, and on further feeding between the conveyers 23, 24, Fig. 1, the bag reaches a pair of cooling jaws 31, 32. The conveyers 23, 24 may comprise belts which prevent the heating jaws 29, 30 from actually touching the web 2, thereby preventing adhesion of the web to the jaws. Alternatively the conveyers 23, 24 may each comprise a pair of chains carrying between them plates (34), Fig. 6 (not shown), with slots to accommodate the heating or cooling jaws, but with a strip (33) of non-adhesive material to prevent adhesion of the web to the jaws. Air jets (93, 94), Fig. 22 (not shown), may be provided at the output end of the conveyers (23, 24) to facilitate detachment of the bag therefrom. Delivery.-On leaving the conveyers 23, 24, Fig. 1, the finished bags are fed on to a conveyer 35 which consists of a series of narrow parallel strips, between which the teeth of a comb-like stop 38 protrude. When the bag reaches the stop 38 the conveyer 35 is pivoted upwardly clear of the stop 38 about an axis 37, by means of a rod 40 linked to the disc 10. A suction carrier associated with the apparatus to which the bag is to be delivered lifts the bag from the conveyer 35. If a bag is not delivered correctly it is pushed off the end of the conveyer 35 by the following bag, after which the conveyer 35 is lowered again to the position shown, where the stop 38 becomes operative again.