Patent GB-1083282-A (GB)
Title: Apparatus for the continuous capacitative welding of thermo-plastic films by means of high frequency currents
IPC: B29C65/00
Filed: 1964-08-13
Abstract: 1,083,282. Dielectric heating apparatus. Z. S. URBANIAK. Aug. 13, 1964 [Aug. 14, 1963 (2); Aug. 21, 1963; Aug. 23 (2)], No. 32997/64. Heading H5H. [Also in Division B5] Apparatus for the continuous welding of thermoplastic films by a high frequency electrical field and pressure comprises two electrodes 1, 2 arranged to grip between them films supported on a table 46 and which electrodes are each mounted on one end of a shaft 3, 4 respectively, mounted by bearings 5, 6 and 7, 8, respectively, in supports 33, 34 carried by levers 27, 28, 29, 30 connected by crossed pull-rods 35, 36 and acted on by coaxial rotating cams 40, 41 so that the electrodes 1, 2 simultaneously perform movements which are the mirror image of each other, one welding cycle comprising gripping the films by the electrodes 1, 2 which are then moved together with the films whilst the latter are welded, opening the electrodes and returning them to their original position.   Tubes 17, 18 are fixed around the shafts 3, 4 to form outer electrodes of coupling capacitors and are connected to a suitable source of current, Fig. 10 (not shown). The shafts 3, 4 are formed with tapered ends or knife edges 14 slidable in resilient guides 15 and leaf springs 16 slidable against fixed surfaces 25. Cooling air 19, 20 is supplied by pipes 21, 22 to the electrodes 1, 2. The electrodes 1, 2 may be provided with extensions 23, 24 and may rotate in a horizontal plane, as indicated by an arrow 9, and the whole system moves as indicated by arrows 10, 11, 12, 13. High-frequency current is supplied to the electrodes 1, 2 during the initial pulse of the move 10 to allow setting of the seal to take place during the remainder of this move. The levers 27, 28, 29, 30 are rotatable about parallel horizontal axes mounted inside a frame 26 rotatable in bearings 37, 38 about its vertical axis. The levers 27, 28 and 29, 30 are connected in pairs by links 31, 32 at one end and by the elements 33, 34 at the other end. The rods 35, 36 interconnect the two systems. The cam 40 engaged by a follower 42 controls the opening and closing of the electrodes and the cam 41 engaged by a follower 43 controls the movements of the electrodes in a horizontal plane. Return springs 44, 45 are provided. The table 46 comprises two superposed plates with a chamber in between to which air pipes 48, 50 are connected. The top plate is provided with holes 47, 51, the latter being drilled oblique to the surface in the direction of movement of the films. A central aperture 59 is provided right through the table 46 to accommodate the electrode 2. A blower 49 blows air through the pipe 50 and the holes 51 and sucks air through the holes 47, the pipe 48, a flow distributing block 52 and a pipe 56 to hold the films in contact with the table. The block 52 is provided with a shutter 57 rotatable with the shaft 58 on which the cams 40, 41 are mounted and closes an opening 54 by which the surrounding air enters the block 52. The shutter 57 closes the opening 54 during the move 11 so that the films adhere to the table 46 and are not conveyed by the electrodes 1, 2. An electronic control circuit is described, Fig. 9 (not shown).