Device for biaxially-oriented stretching polytetrafluoroethylene hollow fiber membranes and method thereof

A device for biaxially-oriented stretching polytetrafluoroethylene hollow fiber membranes, comprising:

• a lubricant removing oven (5) and an adjoining tube blank heating oven (6) that are mounted in turn at an outlet end of an extrusion mould, wherein the lubricant removing oven (5) is configured to reach a temperature of 120˜300° C. to remove lubricant, and wherein the adjoining tube blank heating oven (6) is configured to heat further to 150˜360° C.;
• a core extension linearly extending from a core (3) of the extrusion mould into the lubricant removing oven (5) and partly into the tube blank heating oven (6), the core extension in the tube blank heating oven (6) increasing in diameter such as to form a bulked core (7) that is entirely positioned within the tube blank heating oven (6), wherein the bulked core (7) is configured to for traversely stretch a tube blank while positioned within tube blank heating oven (6);
• and
• a speed regulating guide wheel (9) mounted at the outlet of the tube blank heating oven (6), wherein the speed regulating guide wheel (9) is configured to be wound by and to longitudinally stretch the traversely stretched tube blank by adjusting the speed of the traversely stretched tube blank after leaving the bulked core and wherein the speed regulating guide wheel (9) is positioned under a bottom of the core extension.