| 摘要 |
1,144,347. Seaming non-metallic sheet material. DUNLOP CO. Ltd. 4 July, 1966 [24 July, 1965], No. 31672/65. Heading B5K. At least two sheets comprising a fully crosslinked polyurethane composition are joined by assembling the sheets in contact with each other at the position of the desired joint and applying ultrasonic vibrations to the assembly at this position. The sheets are assembled in overlapping or abuttingrelationship and may be planar or shaped e.g. dished or cylindrical. The sheets may be in the form of an unreinforced film of a fully cross-linked polyurethane composition or a textile fabric, e.g. a woven fabric, a felt or a cord fabric containing little or no weft, coated with the polyurethane composition. The textile fabric may comprise natural or synthetic fibres, e.g. cotton, linen, nylon, regenerated cellulose, polyethylene terephthalate or natural or synthetic rubber. The polyurethane composition may be cellular or non-cellular. Methods of making the polyurethane composition are described. The ultrasonic vibrations are applied by a machine comprising a welding tip vibrated by a magnetostrictive or piezo-electric transducer, means for altering the amplitude of the vibrations of the welding tip, a support anvil for the sheets, and means for adjusting the distance between the anvil and the tip. The welding tip and the anvil may be shaped as rods, laths, rings, discs, sheets or combinations of these shapes. The thickness of the assembly at the position of the desired joint when the vibrations are applied is less, e.g. one-half, the normal thickness of the assembly. If the joint is a butt joint it may be covered by welding one or more strips of similar material over the joint. The invention is applicable to joining parts of containers, e.g. fuel tanks or flexible barges, flexible basins, inflatable articles, dinghies, pneumatic mattresses or protective cloths. |
