GB715781A - Improvements in or relating to the method and apparatus for making thermoplastic resin bags - Google Patents

Abstract

715,781. Making and filling bags. NYE, N. H. April 8 1952 No. 8932/52. Classes 94 (1) and 94 (2) [Also in Group VIII] In an apparatus for making bags from thermoplastic material a longitudinally folded strip of bag material is supplied from a roll 7 mounted on a vertical spindle 12. The strip is fed round a guide roller 22 and a stationary knife 24 separates the sides of the folded strip as it travels to the bag-making station. To move the strip through the various operations, a flat metal finger 33 extends between the opposed sides of the strip, and is supported on a bracket 34 whicn is attached to a reciprocating shaft 35 provided with a housing 37 and guard 38. The shaft 35 is attached to a cross head 40 carried on a slide 41, and through a link 44 and adjustable bell crank 45 which co-operates with a rotating cam disc 55, is reciprocated. The cutting and sealing device comprises an electrically heated flat wire 66, which is suspended vertically on a frame 72 and is spring-loaded to ensure correct tension at all times, The frame 72 is attached to a shaft 75 which is provided with a cam follower co-operating with a cam disc 78 to reciprocate the shaft 75 about its axis and cause rocking motion of the wire 66. A spring 79 secured to the shaft 75 and anchored to the housing 10 resiliently opposes the turning of the shaft and ensures that the wire 66 is returned to its cutting engagement with the strip. To hold the strip in position and to protect the wire 66 a pair of opposed pressure bars 82, having recesses in which the wire may be disposed, are respectively attached to two horizontal shafts 85 which are geared together and provided with reciprocatory rotary motion by means of a cam lever 87 which co-operates with a cam disc 89 to cause the pressure bars to move toward and away from each other. A spring 90 ensures the return of the bars to the open position Two opposed suction tubes 93 are respectively attached to two shafts 95, which are geared together, and are given a rocking motion through a cam follower 99 co-operating with a cam disc 100. A piston 106 in a cylinder 105 is connected to the cam disc 55 for reciprocatory motion and by this means suction is intermittently produced in the tubes 93 to grip the sides of the bag B, and open it for filling purposes. In operation, when the wire 66 and pressure bars 82 are in the starting position, Fig. 5, the finger 33 is moved forward against the previously sealed edge of the bag stock to the position shown in Fig. 6. The suction tubes 93 are then brought close together but leaving sufficient space for the finger to be returned to the position shown an Fig. 7, and the pressure bars are brought against the sheet and the wire 66 moved to cut and seal the adjacent edges of the material. The wire is then moved away from the sheet but the pressure bars continue to grip the sheet while the section tubes move apart to open the bag for filling Figs. 8 and 5. During the filling operation the bags are supported on a trough 110 which is supported on a bracket 111 attached to the reciprocating shaft 35. In this way the trough carries the bag from the cutting station to the filling station. For filling the bags a funnel, Fig. 10 (not shown), is carried by a pivoted lever and is movable through a small angle by means of a lever co-operating with a cam on the shaft 57.