| 摘要 |
994,931. Seaming non-metallic sheet material. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. March 31, 1964 [April 3, 1963], No. 13130/64. Heading B5K. A device for welding together sheets 6, 7 at least one of which is manufactured of, or at least includes plastics, e.g. polypropylene, comprises an anvil 8 to support the sheets 6, 7 and a welding tip in the form of a ball 4, clamped a holder 9, which ball 4 moves relatively in a direction perpendicular to the anvil 8 at an ultrasonic frequency. As shown, electrical energy is supplied to windings 2 to cause the core of a transducer 1 to vibrate ultrasonically. The vibrations are transmitted by an amplitude transformer 3 to the ball 4 which is made of hardened steel and has a polished surface. The ball 4 preferably has a diameter not exceeding fifty times the thickness of the sheets 6, 7 to be welded and is clamped in a conical bore 14, Fig. 2, in a sleeve 13 by a cylindrical member 15 having a conical recess 16 and screwed into the sleeve 13. The length of the transformer 3 and the holder 9 measured from the radiating surface 5 of the transducer 1 to the contact area with the sheets 6, 7 is chosen to be equal to half a wavelength of the ultrasonic vibrations of the transducer 1. The sheets 6, 7 can be drawn over the anvil 8. In a modification (not shown) the ball-shaped welding tip is accommodated in the anvil 8 and the flat end of the transformer 3 directly contacts the sheets 6, 7. The apparatus may also be used to weld nylon fabrics to each other or to textile fabrics and two textile fabrics may be welded to each other with a plastics sheet sandwiched therebetween. |
