Research On Diameter Controlling Technic For Arbitrary Function In The Optical Fiber Drawing Process

It's regarded that the fibre loss and dispersion make a direct impact on system performance in fiber-optic communication systems.And the fiber's on-axis diameter changes have some effects on its loss and dispersion. So the precise control of its core diameter in the drawing process is essential to ensuring the stability of these optical characteristics.Moreover, to provide a certain optical fiber or fibre devices made by it with some special properties of dispersion,it is necessary to make its outer and core diameters change according to a certain curve along the axis,which means that fiber diameter control should be more precise in the fiber drawing process.At present the control section of the existing optical fiber drawing tower belongs to Mitsubishi FX2N series,and it can only be competent for the basic functions.However,for precise control of main traction speed, feed rate, the temperature of graphite oven and curing oven,considering conversion of an analog signal to a 11-bit digital signal,with 2¹¹ steps between specified levels,it can not meet a need of scheduled accuracy,especially which will cause more errors in speed control of electric motor,and directly lead to the bigger gap between diameter changing and curve.This paper researched improving the accuracy of control system by replaying the existing PLC with the one whose accuracy is currently the highest in the market.The quantized samples of an analogue data rise to 15-bit,so the accuracy of fiber diameter control is 16 times higher than that of the older PLC,and the new system could succeed in drawing a certain fiber with special properties of dispersion.In this paper, the main work as follows:To learn function of Siemens S7-300 PLC modules, and construct the new structure of PLC-based control module, which applies to the optical fiber tower.To study functions of configuration software STEP7, complete the ladder chart according to the system structure, and chieve logical control of equipments by PLC.To edit human-machine interface with configuration software WinCC, and write the functions of fiber diameter control with C-script, which could make optical fiber's outer diameter change according to arbitary curve along the axis.