| 摘要 |
<p>875,886. Seaming non-metallic sheet materials. RADIO HEATERS Ltd., and SUMMERS & SONS Ltd., JOHN. Dec. 17, 1959 [Jan. 13, 1959], No. 1264/59. Class 42 (1). A method of sealing the inner thermoplastic layer 1, Fig. 2, of a container of laminated material formed of a thermoplastic and a metal layer comprises welding a strip 17, Fig. 3, of thermoplastic material to the two edges of the layer 1 by radio-frequency dielectric heating means, the strips 17 being arranged to overlie the seam 4 formed by overlapping edges of the outer metal layer 3. A lower electrode 8 with a shoulder 9 for accommodating the seam 4 cooperates with a pair of upper electrodes 10, 11 mounted rigidly or resiliently on a beam 12 which is carried by supports 13, 14, the support 14 being pivoted to permit the insertion of the container. The strip 17 is held against the electrodes 10, 11 by connecting an aperture 18 to a source of partial vacuum. The electrodes 10, 11, which have flat, convex or stepped welding faces, are lowered by means, e.g. pneumatic cylinders, acting on .the beam 12. Clamps 21, 22, 23 may be provided to flatten out any irregularity of the container and ensure even pressure between the electrodes during seaming.</p> |
