| 摘要 |
778,777. Seaming non - metallic sheet material. BUCHANAN MASH & CO., Ltd., and LEECH, C. H. March 4, 1955 [Jan. 1, 1954], No. 80/54. Class 42 (1). [Also in Group XI] A smooth seam is produced between two thermoplastic sheets, or an existing seam is smoothed, by means of a pair of smooth flat high-frequency electrodes which press the material at the seam to a thickness substantially equal to that of a single sheet of the material, the operative face of at least one of the electrodes having a covering sheet of flexible, low dielectric loss, heat resistant insulating material. As shown, Fig. 1, the overlapping edges of sheets 14, 15 are welded between electrodes 1, 2 having covering sheets 5, 6 of woven fabric made of " Terylene " (Registered Trade Mark) impregnated with a synthetic resin varnish or of woven glass fabric impregnated or coated with a silicone resin or silicone rubber. The apparatus is provided with means for pressing the electrodes together and an adjustable stop to prevent the electrodes approaching closer than about the combined thickness of the cover sheets and one of the sheets 14, 15. Instead of the sheets being overlapped as shown, they may previously have been seam welded face to face by an electrode which simultaneously trains off the waste material at the seam. The sheets are then opened out flat and the upstanding seam placed between electrodes 1, 2 which operate to smooth the existing seam. |
