Patent GB-1519713-A (GB)
Title: Method and and apparatus for manufacturing products of uniform size from a webof sheet material
IPC: B31B23/00
Filed: 1976-07-01
Abstract: 1519713 Seaming non-metallic sheet material; bag making apparatus M LINDQVIST 1 July 1976 [7 July 1975] 27383/76 Headings B5K and B5D Apparatus for forming articles 17, e.g. plastics bags, of uniform length by cutting and welding a web 10 of sheet material, comprises a vertically displaceable receiver 11 for receiving the formed articles 17; a trolley 14 reciprocable above the receiver 11 for feeding the web 10 downwardly and which is provided with means for cutting and welding the web to form the articles; and means for controlling the extent of movement of the trolley 14 to each side of a plane of symmetry A-A through the receiver 11. As shown in Fig. 1, the receiver 11 comprises a table 15 which carries a pallet 16 to receive the bags 17 produced. The table 15 is carried by an hydraulic piston and cylinder device 18 so as to be lowerable in step with the bags 17 piled thereon. The table is displaceable parallel to the direction of movement of the trolley 14 a short distance to either side of the plane A-A at predetermined intervals so as to subdivide the pile into individual layers each comprising a predetermined number of sacks so that outer surfaces of alternate layers are aligned. The trolley 14, Fig. 2, carries wheels 30 which run on rails 13 and is driven by a motor 31 via gearing in a housing 37 and which also drives a feed roller 32, co-operating with a free-floating support roller 33. As shown, in Figs. 4 and 6, the output shaft of the motor 31 carries a pinion 40 meshing with two gears 41, 42 freely rotatable trunnions 43, 44 in the trolley. Gears 45, 46 are are non-rotatably mounted on the trunnions 43, 44 and are co-operable with fixed racks 19, 20. The gears 45, 46 mesh with a gear 47 on the roller 32. Clutches 49, 50 are mounted on a swingable arm 48 which alternately locks the gear 41 to the trunnion 43 or the gear 42 to the trunnion 44, respectively, to drive the roller 32 in one direction only. Actuation of the arm 48 is governed by switches 21, 22, Fig. 1, which determine the ends of the path of movement of the trolley 14 and are adjustable in position. The trolley 14 is provided with reciprocable welding means 34 to form a seam 35 in the web 10 and reciprocable cutting means 36 to perforate or completely sever the bags from the web 10. The apparatus may operate to perform one weld and one cut at each end of the path of movement of the trolley 14 so that, in the pile 17, two superimposed seams at each side are separated, by an open end of an intermediate bag, Fig. 1A (not shown). Alternatively, the trolley may perform one complete reciprocation between each welding and cutting operation so that each bag is folded in half, Fig. 7 (not shown). In a further alternative, a full length of a bag is fed out whilst the trolley rests at an end position and welding and simultaneous spreading of the bag are effected as the trolley moves towards the opposite end position at which cutting is effected. In modifications (not shown), (a) the trolley is reciprocated by long-stroke hydraulic cylinders; (b) the racks are located along opposite longitudinal sides of the trolley and gears at both ends of the roller 32 co-operate with these racks, electromagnetic clutches being provided to alternately lock these gears to a driving shaft, (c) the roller 32 is driven by a reversible motor; (d) a further pair of welding means is located below the cutting means 36; (e) the table 15 is replaced by a bar mounted in a vertically displaceable rack and is removable when a desired number of sacks has been deposited thereon; and (f) the table 15 is replaced by and endless chain movable each time a predetermined number of bags have been deposited thereon.