Abstract: The method, in which base material ingot 1 is heated and softened in an electric furnace 3, drawn with a pair of pinch roller 6 and 6, and elongated to make base material rod 7 having a smaller diameter than the ingot, features: forming either a roller groove 11 having a curvature radius which is larger than the outer diameter of the base material rod 7 or a V-shaped roller groove 11 having the cross section consisting of straight lines on the surface of the pinch roller 6 made of metal; nipping with the facing roller grooves 11 and 11 respectively formed on the surfaces of a pair of said pinch rollers 6 and 6; and drawing said base material rod.

Abstract: There is provided an elongation method of an optical fiber base material, by which a base material rod not requiring a process for modifying a bend from base material ingot is obtained. The method for elongating base material ingot to be a base material rod having a diameter smaller than before to manufacture an optical fiber base material, includes the steps of: elongating the base material ingot while controlling a control position so that a neck-down within a horizontal surface of the base material ingot is located at a target position; measuring a bending direction and a bending amount of an elongated base material rod; and adjusting the target position based on the result. In addition, it is preferable to adjust a position of a pendant portion of base material ingot in order to control the position of the neck-down to be the target position. For example, the position of the pendant portion may be moved in an XY direction, more particularly, in a direction in which the measured bend shows convexity.

Abstract: The method, in which base material ingot 1 is heated and softened in an electric furnace 3, drawn with a pair of pinch roller 6 and 6, and elongated to make base material rod 7 having a smaller diameter than the ingot, features: forming either a roller groove 11 having a curvature radius which is larger than the outer diameter of the base material rod 7 or a V-shaped roller groove 11 having the cross section consisting of straight lines on the surface of the pinch roller 6 made of metal; nipping with the facing roller grooves 11 and 11 respectively formed on the surfaces of a pair of said pinch rollers 6 and 6; and drawing said base material rod.

Abstract: There is provided an elongation method of an optical fiber base material, by which a base material rod not requiring a process for modifying a bend from base material ingot is obtained. The method for elongating base material ingot to be a base material rod having a diameter smaller than before to manufacture an optical fiber base material, includes the steps of: elongating the base material ingot while controlling a control position so that a neck-down within a horizontal surface of the base material ingot is located at a target position; measuring a bending direction and a bending amount of an elongated base material rod; and adjusting the target position based on the result. In addition, it is preferable to adjust a position of a pendant portion of base material ingot in order to control the position of the neck-down to be the target position. For example, the position of the pendant portion may be moved in an XY direction, more particularly, in a direction in which the measured bend shows convexity.

Abstract: A method for manufacturing a base material for an optical fiber, includes steps of: holding a bar material by a support member; and adjusting to reduce a difference between an axis of the bar material and a rotational axis of the support member. Furthermore, an optical fiber base material grasping apparatus for holding a bar material having an axis, includes: a support member having a center axis, the support member being rotatable around the center axis; and an adjusting mechanism for reducing a difference between the axis of the bar material and the central axis of the support member.

Abstract: A method for drawing a glass ingot comprises holding a vertically suspended glass ingot 5 at an upper end thereof, passing the ingot through a heating furnace 10 having upper and lower openings, and drawing the glass ingot while moving one end or both ends thereof, wherein a plurality of heating means 1 are provided along vertical directions in the heating furnace 10, and the temperatures of the respective heating means 1 are individually control to control a temperature distribution within the heating furnace 10.