Patent GB-904146-A (GB)
Title: Apparatus for the production of block bottom bags or sacks
IPC: B31B3/00
Filed: 1959-06-25
Abstract: 904,146. Making bags. OTT, K., [trading as HABRA-WERK WILHELM F. OTT]. June 25, 1959 [June 26, 1958; March 18, 1959], No. 21916/59. Addition to 813,217. Class 94(2). The invention of the parent Specification, which is essentially a succession of spreading plates comprised in apparatus whereby tubing is pushed over a pair of closed spreading plates, the length of tubing on the plates is cut off and sealed and the plates are advanced along guide bars and the movement used to cause their separation, so opening the tubing into a bag, is modified in that gripping jaws 107, 108 are combined with cutters 33a, 34a and welding jaws 24a, 25a in a unit which is vertically movable in line with a pre-opening mandrel 5 to feed tube lengths S to the spreading plates 6, 7. The unit comprises arms 112, 113 which can open and close about a common shaft 114 and the shaft is guided for vertical movement in bushings, 117, Fig. 10. The movement may be performed by a hydraulic cylinder 118, alteration of the stroke of the piston giving alteration in the bag length of tubing. Downward movement of the unit moves lever 122 which has a cam profile that interacts with a disc 121 so that the disc rotates in a direction to rotate a roller (not shown) on the disc shaft whereby tubing S, pre-opened by the mandrel 5, is pushed a suitable distance on to the spreading plates. Cam bars 109, 110 are moved towards and away from one another, about pivots 111, by any suitable means, not shown. Tubing entering the machine is directed by a guide plate in a vertical direction and between rollers 21 which move it over the pre-opening mandrel 5. The mandrel 5 is pear-shaped in cross-section and the advancing end of the tubing is cut obliquely, the longer edge being situated below the thicker side edge of the mandrel. Springs 106 at the upper end of the mandrel 5 assist in slightly opening the tube. The slightly opened tube S passes over the tip of the closed spreading plates 6, 7 which are brought to their position by a conveyer as described in the parent Specification and the cam bars 109, 110 are at their greatest distance apart, Fig. 5. In this starting position rollers 115, 116 on the gripping jaws 107, 108 are in recesses 119, 120 in the cam bars 109, 110. When the unit starts to move upwards the cam bars 109, 110 come together and, through the rollers 115, 116 on the ends of the same 112, 113, close the welding jaws 24a, 25a and the cutters 33a, 34a but the gripping jaws remain apart till the tube length for a bag has been cut off and heat-sealed so that the severed upper part is free to move upwards. On further upward movement of the unit the rollers 115, 116 run out of the recesses 119, 120 and the jaws 107, 108 grip the longitudinal welded edges 3, 4 of the tube, Figs. 7 and 8, current then being supplied to the welding jaws 24a, 25a The cam bars 109, 110 then swing outwards and the bag length of tube is pushed completely on to the spreading plates 6, 7 which then move one step further along their conveyer, the next pair of spreading plates taking their place. The feed rollers 21 may be intermittently rotated from the vertical movement of the unit through an arrangement of connecting-rods and crank arms with free wheel connections. Clamping strips may be situated on the welding jaws to feed the tubing upwards in addition to the action of the gripping jaws. Another modification to the parent invention comprises plates 6a, 7a, Figs. 4a, 4b, pivoted to the spreader plates 6, 7, which, in the Fig. 4b position, together form a backing plate in the bag and function as supporting means for the operation of gluing the end tabs described in the parent Specification, the separate guide plates mentioned therein thus being obviated. A third modification to closer spacing of the pairs of spreading plates on their conveyer, resulting in more compactness.