Molding device and molding method for optical fiber preform

Patent metadata

Field	Value
Publication number	US-11970420-B2
Application number	US-202217806687-A
Country	US
Kind code	B2
Filing date	Jun 13, 2022
Priority date	Mar 30, 2022
Publication date	Apr 30, 2024
Grant date	Apr 30, 2024

Abstract

A molding device and a molding method for an optical fiber preform are provided. The molding device includes a rotating mechanism, an extrusion mechanism, and a cylinder mold that is of a cylindrical structure with two ends each having an opening. After a hollow cladding sleeve is obtained by rotating the cylinder mold through the rotating mechanism, a molten core glass is then reversely extruded into the cladding sleeve in the cylinder mold from bottom to top by the extrusion mechanism to prepare the optical fiber preform.

First claim

What is claimed is:

1. A molding device for an optical fiber preform, the molding device comprising a rotating mechanism, an extrusion mechanism, and a cylinder mold for preparing a hollow cladding sleeve, wherein the cylinder mold is of a cylindrical structure with two ends each having an opening, a corresponding one of two detachable plugging portions of the rotating mechanism is fitted with the opening, and the cylinder mold is rotationally connected to the rotating mechanism through the two plugging portions;
wherein the extrusion mechanism comprises a top die, an extrusion head and a bottom die, the top die is detachably connected to a first end of the two ends which is a top end of the cylinder mold vertically arranged, and the top die is formed with a through portion enabling a molten core glass inside the cladding sleeve to flow out; the extrusion head is located at a second end of the two ends which is a bottom end of the cylinder mold vertically arranged, and is provided with a feeding channel in communication with the cladding sleeve; the bottom die for pressing the molten core glass into the feeding channel is arranged at an inlet of the feeding channel; and a heat resisting cylinder is provided between the extrusion head and a bottom end of the cladding sleeve, and the heat resisting cylinder is formed with a flow guide channel for communicating the feeding channel and the cladding sleeve;
wherein the cylinder mold is connected to the rotating mechanism, and a heating jacket is arranged at a periphery of the cylinder mold;
wherein an end cylinder coaxial with the cylinder mold is arranged at an inner side of the cylinder mold, and an outer diameter of the end cylinder is matched with an inner diameter of the cylinder mold; and
wherein the cylinder mold is connected to the extrusion mechanism, an annular gasket coaxial with the cylinder mold is arranged at an inner side of the top end of the cylinder mold, the annular gasket has same inner and outer diameters as the end cylinder, and the top die abuts against the annular gasket.

2. The molding device for the optical fiber preform according to claim 1 , wherein an outer diameter of the heat resisting cylinder is matched with the inner diameter of the cylinder mold, and the flow guide channel and the cladding sleeve are coaxial and have same inner diameters.

3. The molding device for the optical fiber preform according to claim 2 , wherein an inlet end of the feeding channel is arranged downwards, the bottom die is of a groove-shaped structure having an opening facing upwards, and an open end of the groove-shaped structure is slidingly sleeved outside a peripheral side of the inlet end of the feeding channel in a vertical direction.

4. The molding device for the optical fiber preform according to claim 3 , wherein the inlet end of the feeding channel is of a tapered structure diminishing from bottom to top.

5. The molding device for the optical fiber preform according to claim 4 , wherein a profile of a narrow end of the tapered structure is matched with an inner cavity of the cylinder mold and is inserted into the inner cavity of the cylinder mold, and the narrow end of the tapered structure has a same inner diameter as the cladding sleeve.

6. The molding device for the optical fiber preform according to claim 5 , wherein the rotating mechanism comprises two driving shafts which are located at the two ends of the cylinder mold respectively and are provided coaxial with the cylinder mold; each of the two plugging portions comprises two annular flanges which are respectively provided on the cylinder mold and a corresponding one of the two driving shafts, and the two annular flanges are detachably and hermetically connected through an annular fastener.

7. A molding method for an optical fiber preform, the molding method comprising:
preparing: enabling a cylinder mold to pass through a heating jacket, connecting and fixing a first end of the cylinder mold to a first driving shaft of two driving shafts through a first annular fastener, and placing an end cylinder in the cylinder mold, turning on the heating jacket, performing heat preservation at 200-350° C. for 0.5-1 h, and placing a second driving shaft of the two driving shafts in an electric furnace for heat preservation at 200-350° C. for 0.5-1 h;
melting: melting cladding glass and core glass successively in a melting furnace, wherein the cladding glass is weighed quantitatively based on a core diameter of the optical fiber preform;
pouring the molten cladding glass: placing the cylinder mold with an opening at a second end of the cylinder mold facing upwards vertically after the first end of the cylinder mold is connected and fixed, pouring the molten cladding glass into the cylinder mold, taking out the second driving shaft, and connecting and fixing the second driving shaft to the second end of the cylinder mold through a second annular fastener;
rotating: maintaining the cylinder mold and the two driving shafts in a vertical state, and rotating the two driving shafts at a rotational speed of 3000 r/min, waiting for 5-10 s and laying the cylinder mold and the two driving shafts stably, continuing to keep the cylinder mold for heat preservation at 200-350° C., and turning off the heating jacket to enable the cylinder mold to be cool naturally after the cylinder mold is rotated for 3-60 min, wherein, upon rotation of the cylinder mold, a bottom die and an extrusion head are put into the electric furnace for heat preservation at 400-600° C. for 0.5-1 h in advance;
mounting an annular gasket and a heat resisting cylinder: dismounting the first annular fastener and the second annular fastener at two sides of the cylinder mold, taking out the cylinder mold and placing the cylinder mold horizontally, pushing a cladding sleeve to the first end of the cylinder mold to replace the end cylinder with the annular gasket and enabling the annular gasket align with the first end of the cylinder mold, cutting off a narrow portion of the cladding sleeve to ensure that two ends of the cladding sleeve are of opening structures; and placing the heat resisting cylinder in the second end of the cylinder mold, and then placing the cylinder mold as a whole in the electric furnace for heat preservation at 200-450° C. for 0.5-1 h;
mounting a top die, the extrusion head and the bottom die: taking out the bottom die from the electric furnace, pouring the molten core glass into the bottom die, taking out the extrusion head from the electric furnace and mounting the extrusion head on the bottom die, and taking out the cylinder mold and enabling the first end of the cylinder mold which is provided with the annular gasket to face upwards, placing the cylinder mold wholly and vertically, mounting the extrusion head at the second end which is a bottom end of the cylinder mold, and placing the top die at the first end which is a top end of the cylinder mold;
extruding: transferring the cylinder mold installed with the top die, the extrusion head and the bottom die to a hydraulic machine, turning on the hydraulic machine and setting an extrusion speed to be 0.4-5 mm/s; extruding the molten core glass reversely into the cladding sleeve stably; stopping extruding in response to observation through the top die that the molten core glass overflows; remaining a position of the hydraulic machine unchanged, waiting for 30-300 s and taking out the cylinder mold; and transferring the cylinder mold into the electric furnace to be annealed for 3-6 h, and cooling the cylinder mold to room temperature in the electric furnace; and
taking out a product: disassembling the cylinder mold and taking out the optical fiber preform.

Assignees

• Univ Jiliang China

Inventors

• Xu Shiqing
• Hua Youjie
• Li Bingpeng
• Tian Ying
• Huang Feifei
• Zhang Junjie
• Cai Muzhi
• Ye Renguang

Classifications

• C03B37/01274 Primary

  by extrusion or drawing · CPC title

• C03B25/02

  in a discontinuous way · CPC title

• C03B37/01268 Primary

  by casting · CPC title

• C03B37/01271 Primary

  by centrifuging · CPC title

• C03B37/01265

  starting entirely or partially from molten glass, e.g. by dipping a preform in a melt · CPC title