| 摘要 |
1,128,087. Seaming non-metallic sheet material. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 18 Nov., 1966, No. 51845/66. Heading B5K. Apparatus for thermally welding and severing thermoplastic films, e.g. polyethylene films, comprises a welding device 10 and a welding base 11 engageable with each other to weld and sever thermoplastic films between them, the welding face of the device 10 being formed by a sheet 13 of heat-resistant non-sticking material stretched over an electrically heatable element 12 and having at least one side 15 sloping relative to the films and the welding face of the base 11 being formed by a sheet 14 of heat resistant non-sticking material which is supported in a non-elastic manner. Preferably, the sheets 13, 14 are made of glass-fibre reinforced polytetrafluoroethylene and a sheet 20 of this material is laid between the element 12, comprising an electrical resistance wire, and the body 16 of the device 10. As shown, both sides 15 of the sheet 13 slope relative to the films. The body 17 of the base 11 is made of metal or other hard material not deformed by by the pressures applied during welding and severing. The body 17 may be heated, e.g. by electrical heating elements therein or between the body 17 and the sheet 14 or by circulating a hot fluid through passages therein. Alternatively, the base 11 may be provided with means for cooling the body 17. The device 10 and the base 11 are movable towards and away from each other either manually or mechanically. |
