| 摘要 |
716,783. Packaging - machines. RADO, L. April 5,1950, No. 8624/50. Class 94 (1) In a machine for producing thermoplastic containers, filled with liquid or paste, by flattening and welding together opposed walls of a length of filled tubing at spaced points, the filled tubing 9. Fig. 1, is fed between endless chains 1 and 2 passing over driving sprockets 3, 4 and 5, 6 and carrying jaws 7 and 8 respectively which are spaced apart along the chains by distances equal to the length of one container and move in registering relationship along the lower run 1a of the chain 1 and the upper run 2a of the chain 2. The jaws are guided by insulated members 10 and 11 which are so shaped that the jaws are progressively moved closer together to flatten the tube at spaced points, thereby displacing the filling from the areas where welding is to be effected. The jaws then move on to conductive portions 12, 13 of the guide members, whereby they are connected to a source of high-frequency current to effect the welding, the portions of the guide members immediately in advance of the portions 12, 13 being sloped inwardly so that the jaws are moved closer together to compensate for the softening of the walls of the tubing when it is heated. To avoid sparking, each jaw 7 is arranged to close a switch 15 in the electrical circuit after it has engaged the portion 12 and to open the switch before it leaves the portion 12. The construction of the jaws is shown in detail in Figs. 2-4, each jaw 7 comprising a central part 7a, slidable against the action of a spring 16 in a casing 17 engaging the guide 10, and insulated outer parts 7b, movable relative to the part 7a against the action of springs 7c which protect the softened areas of the tubing in contact with the filling. Each jaw 7 houses a slidable cutter 21 which is moved downwardly by a fixed cam 23 into a recess 24 in the co-operating jaw to sever each filled container from the tubing. The movement of the jaws towards one another is limited by insulated stops which may be adjustable, see Figs 5-7 (not shown), and each jaw 8 is fitted with flared guides 20, Fig. 8 (not shown), which engage the co-operating jaw 7 as the jaws move on to the adjacent runs of the chains to prevent relative longitudinal movement thereof. Before being fed to the apparatus of Fig. 1, the tubing 9 may be subdivided longitudinally by endless metal bands 25, 25a, Fig. 13, heated by electrical resistances 26 and driven at the same speed as the chains 1, 2, the bands being cooled by air jets 27 after they have effected the longitudinal welding of the tubing. |
