Method for manufacturing tube-shaped silica glass product

This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for MANUFACTURE METHOD FOR SILICA GLASS OF TUBE TYPE earlier filed in the Korean Industrial Property Office on the Aug. 26, 1999 and there duly assigned Serial No. 35602/1999. A silica product, method and apparatus for manufacturing a tube-shaped silica glass product using a molded green body having a hollow rod structure. A molded green body having a hollow rod structure has a uniform outer diameter and has a bore having an inner diameter increasing gradually from one end to the other. When sintered in a vertically movable sintering furnace, a tube-shaped silica glass product having a longitudinal cross section distribution less than a tolerance limit may be obtained. Optical fiber manufactured using the silica glass tube according to the present invention may have a uniform longitudinal geometrical structure, thereby exhibiting superior transmission characteristics.