Patent GB-1130840-A (GB)
Title: Dielectric heating apparatus
Inventor: SUTCLIFF ROBERT CLYDE
IPC: B65B51/22
Filed: 1967-06-29
Abstract: 1,130,840. Packaging between webs. EASTMAN KODAK CO. 29 June, 1967 [5 July, 1966], No. 30125/67. Heading B8C. [Also in Divisions B5 and H5] Apparatus for forming a succession of filled containers 67, Fig. 5, from superposed webs 70, 71 of plastics material comprises a wheel rim 17, Fig. 1, supported by a rotatable drive shaft 11 but electrically insulated therefrom by a mica insulator 15, a plurality of outwardly facing electrodes forming the periphery of the rim 17, a plurality of inwardly facing electrodes 50 each radially alignable with a co-operating outwardly facing electrode and drivable towards a mating position in which a container forming recess is defined between the co-operating electrodes during a portion of rotation of the wheel 10, and a plurality of inductors 40 coupled to the electrodes to form a tunable circuit, including the capacitive coupling between the electrodes, which is adapted to be energized by a power source 25 during said portion of rotation of the wheel 10 in order to produce dielectric heating and sealing of the webs 70, 71. The rim electrode 17 is energized from a high voltage plate 18 secured to rotate with the wheel 10 and electrically coupled through a slip ring 19 and brushes 20 to a non-rotatable plate 21 energized from a " hot " line 22 of a coaxial cable 23, which line 22 is supplied by a generator 25. The earthed outer cover of the cable 23 is secured to a non-rotatable plate 27 mounted on, but not electrically coupled to, the plate 21 and is electrically coupled by a slip ring and brush assembly 28 to earth a plate 29 electrically coupled to and mounted to rotate with the wheel 10. Each package forming station is constituted by a pair of cups 35 surrounded by rims 36 in the electrode 17 which is perforated by apertures 34 connected by conduits 33, 30 through a nozzle 32 to a vacuum source 31 to hold the webs 70, 71 in contact with the electrode 17. The inductors 40 and capacitors 41 are connected in series between the plates 18, 29 to rotate therewith. Each inductor 40 is tunable by a slotted plug 42 selectively positioned through a lock washer 43. Each pair of cups 35 is coupled to the plate 18 by a peripheral hoop 47 and each capacitor 41 is secured between hoops 46, 47. Straps 49 secure the hoop 46 to the coil 40 and support the plug 42 and the washer 43. Each electrode 50 comprises a cap mounted on a support 52 to rotate with the wheel 10 and is provided with rims 36 to co-operate with the rims 36 on the electrode 17. The electrodes 50 are closable by a cam drive assembly 54 selectively raisable and lowerable radially on a shaft 55 as the wheel 10 rotates by a cam follower 57 traversing a stationary annular track 58. Each electrode 50 also carries a cam follower 63 which engages a cam arrangement 62 biased towards the wheel 10 by springs 61, Fig. 5, to compress the electrodes 17, 50. The apparatus is used to form packets 67 comprising layers 72, 73, 74 sandwiched between the webs 70, 71 and at least one of which is a dental X-ray film sheet and are carried by an endless belt 75 tensioned by a spring 78. The compression exerted by the rims 36 on the webs 70, 71 weakens the webs and facilitates removal of each individual packet 67.