Method for manufacturing large-sized optical fiber preform rod guide cone

The invention discloses a method for manufacturing a large-sized optical fiber preform rod guide cone. The method comprises the following steps: melting an optical fiber preform rod in a fiber drawing furnace; pulling the guide cone out and cooling to room temperature; scanning data of diameter change of the guide cone of the cooled optical fiber preform rod along the axial direction by using a laser diameter measuring instrument; drawing the shape of the guide cone according to the data scanned by the laser diameter measuring instrument; drawing a shape curve of a grinding tool which is complementary with the guide cone according to a drawn shape curve of the guide cone, and machining the outer surface of a basal body of the metal grinding tool with the curve; plating carborundum with granularity of 30-150 meshes and thickness of 2-8 mm on the surface of the basal body of the metal grinding tool to manufacture the grinding tool; grinding one end of a quartz socket tube by using the grinding tool to manufacture a conical head; butting the conical head against the quartz socket tube with a diameter which is not greater than the minimum diameter of the conical head on a welding lathe; drawing out a front cone.