| 摘要 |
866,063. Seaming non-metallic sheet materials. FARBWERKE HOECHST A.G. Dec. 9, 1957 [Dec. 7, 1956], No. 38248/57. Class 42 (1). A method of welding stretched foils of weldable thermoplastic material such as polythene wherein the surface portions of the regions to be welded are softened to a depth equal to about one-tenth to about one-half of the thickness of the foil and the surfaces of the foils remote from the surface portions to be softened are cooled by cooling rollers or by directing a cooling medium such as air to the surfaces. As shown, two foils 7, 8 are passed over a heating- bar 9, the foils being cooled by elements 10, 11 and pressed together by pressure rollers 12, 13 to form the welded joint and simultaneously advance the foils. Specifications 799,392, 799,823 and 801,031 are referred to. |
