Device and method to protect OVD (outside vapor deposition) transmission screw

Abstract

The invention provides a device to protect an OVD (outside vapor deposition) transmission screw. The device comprises a spray lamp platform slidably mounted on a guide rail; the spray lamp platform isfitted with a plurality of spray lamps; a transmission screw corresponding to the spray lamp platform is provided with a screw protective cover that is provided with a plurality of air holes; nitrogen is introduced into the screw protective cover, and a positive pressure cavity is formed in the transmission screw; a temperature sensor and pressure sensor for controlling introduced flow of nitrogen are arranged in the screw protective cover. The levelness of the transmission screw is optimized; the outer diameter of a loose member is more uniform; scrapping rate due to thread diameter fluctuation in a drawing process is decreased, and fiber drawing yield is increased. In addition, the risk for preform cracking during the deposition process is decreased. By optimizing the levelness of the transmission screw, the spray lamp platform is at more uniform speed when moving back and forth; the density distribution of the loose member is more uniform, so that scrapping due to cracking that iscaused by nonuniform density of the loose member is decreased.

Description

technical field [0001] The invention belongs to the technical field of optical fiber preform manufacture and research and development, and in particular relates to a device and method for protecting an OVD drive screw. Background technique [0002] The OVD (Outside Vapor Deposition) process is currently one of the best processes for preparing low water peak or zero water peak single-mode optical fiber preforms. This process is widely used by mainstream optical fiber preform manufacturers at home and abroad. The mandrel prepared by OVD process is composed of core layer and optical cladding. [0003] The OVD process equipment mainly consists of three parts: chemical vapor phase reaction and deposition chamber, gas blowtorch and soot preform rotating mechanism. The OVD blowtorch system is usually designed with multiple sets of blowtorches. The core blowtorch and the blowtorch platform are installed directly under the preform through the screw rod under the platform. SiO prod...

AI Technical Summary

Problems solved by technology

However, under normal circumstances, due to the long screw rod, it is easy to deform in the high temperature environment of the deposition process. In addition, the deposition chamber is an acidic environment, and the SiO formed by the reaction 2 Particles are easily adsorbed on the surface of the transmission screw. Long-term use will lead to poor precision of the screw, resulting in uneven density distribution of loose bodies, easy cracking, large diameter differences, and even gas lines. In addition, it will also reduce deposition efficiency.

At the same time, the iron ions produced by the corrosion of the screw rod by the acid gas will volatilize under high temperature conditions, and will be carried by the airflow and penetrate into the optical fiber preform, which will affect the quality of the optical fiber preform, resulting in unqualified optical fiber preform and scrapping The rate increases, increasing the production cost of optical fiber preform

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