| 摘要 |
1,030,035. Extrusion dies; tubular film extrusion nozzles. E. I. DU PONT DE NEMOURS & CO. Aug. 4, 1964 [July 24, 1963], No. 30896/64. Headings B5A and B5B. A die for the extrusion of a tubular film of polytetrafluoroethylene comprises a mandrel having a divergent surface 12 remote from an a convergent surface 15 near the extrusion orifice 16, and a smoothly contoured intermediate area 14, and the die body 10 has an inner wall surface 13 having a convergence substantially the same as that of the surface 15 and being spaced therefrom a distance of 5 to 15 times the thickness of the extruded film. Polytetrafluoroethylene powder mixed with lubricant is forced through the die by a piston (not shown). An alternative apparatus is described for coating a wire by extrusion.
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