| 摘要 |
<p>729,742. Seaming non-metallic sheet material. ENGLISH ELECTRIC CO., Ltd. Feb. 13, 1953 [Nov. 19, 1951], No. 27055/51. Class 42 (1). [Also in Group XI] Thermoplastic material, such as polythene, which has a low power factor at frequencies employed in high-frequency dielectric heating apparatus, is welded by applying to the material a tool which is heated by electromagnetic induction so as to cause local softening of the material, the tool being subsequently cooled to solidify the material of the weld while maintaining the weld under sufficient pressure to cause adhesion. Two sheets of material may be welded together between a pair of opposed metal jaws, each arranged in the field of a work coil capable of being supplied with highfrequency energy; when the material is softened, the electrical supply is cut off and the jaws are cooled by cooling fluid such as water which is passed through ducts in the jaws close to the working surfaces, the material being maintained under sufficient pressure to cause adhesion.</p> |
