| 摘要 |
1,056,970. Heat shrinkable tubing. INTERNATIONAL STANDARD ELECTRIC CORPORATION. May 21, 1965 [May 22, 1964], No. 21595/65. Heading B5A. Heat shrinkable tubing is made by heating an extruded tube of crystalline polymeric material to at least its crystalline melting point at which temperature the material exhibits elastomeric properties, applying fluid under pressure to expand the tube to the required predetermined diameter as it is drawn through a die which extends through the heating and cooling chambers. The metal die 5 extends through a heating chamber 6 circulated by hot oil, a cooling chamber 7 and a rinsing chamber 8. Extruded tubing 2 of crystalline polymeric material, wrapped around by tape 4 from a reel 4a which acts as a carrier for the tubing, is continuously pulled through the metal tube 5 by a driven take-up reel 16 for the tape. Compressed air is applied to the tubing by a pump, one end of the tubing being attached to the pump while the other end is closed. In the heating chamber the tubing expands and since the internal pressure is maintained in the cooling and rinsing chambers the tubing sets at the expanded diameter, which is in fact equal to that of the metal tube minus the thickness of the carrier tape. The expanded tubing is coiled on a rotating table 11. The metal tube 5 is perforated so that hot oil enters it in the heating chamber to increase heat circulation, the oil being washed from the expanded tubing in the rinsing chamber. The tubing may be patterned by using a roughened or embossed carrier tape. The carrier tape may be in the form of an endless belt and may be of metal foil, fulric plastics or elastomeric coated material. The crystalline polymeric material may be produced by subjecting a crystalline polymer to irradiation, or may be chemically cross-linked polymers or mixtures of chemically cross-linked elastomers and crystalline polymers. Examples include P.T.F.E., polyethylene, polypropylene, P.V.C., P.V.D. and polyamides. |
