High-Speed Glass Fiber Drawing from Heated and Softened Silica Preform in an Optical Fiber Draw Furnace

2012 ◽  
Vol 8 (1) ◽  
pp. 439-444
Author(s):  
Ho Sang Kwak ◽  
Dongjoo Kim ◽  
Kyoungjin Kim
Keyword(s):  
Optical Fiber ◽  
Glass Fiber ◽  
High Speed ◽  
Fiber Drawing

Analytic Study of Non-Newtonian Double Layer Coating Liquid Flows in Optical Fiber Manufacturing

2012 ◽  
Vol 224 ◽  
pp. 260-263 ◽  
Author(s):  
Kyoung Jin Kim ◽  
Ho Sang Kwak
Keyword(s):  
Optical Fiber ◽  
Glass Fiber ◽  
Double Layer ◽  
Optical Fibers ◽  
Newtonian Fluid ◽  
Liquid Flow ◽  
Analytic Study ◽  
Fiber Drawing ◽  
Drawing Speed ◽  
Layer Coating

In mass manufacturing of optical fibers, the wet-on-wet polymer resin coating is an efficient process for applying double layer coatings on the glass fiber. This paper presents an analytic study on the behavior of non-Newtonian polymer resins in the double layer coating liquid flow inside a secondary coating die of the optical fiber coating applicator. Based the approximations of fully developed laminar flow and the power law model of non-Newtonian fluid, the coating liquid flow of two immiscible resin layers is modeled for the simplified geometry of capillary annulus, where the surface of glass fiber moves at high fiber drawing speed. The effects of important parameters such as non-Newtonian fluid properties, the coating die size, and fiber drawing speed are investigated on the resin velocity profiles and secondary coating layer thickness.

Helium-Injection Cooling of Hot Silica Glass Fiber in Optical Fiber Manufacturing System

2012 ◽  
Vol 157-158 ◽  
pp. 1301-1304
Author(s):  
Dong Joo Kim ◽  
Il Seok Oh ◽  
Ho Sang Kwak ◽  
Kyoung Jin Kim
Keyword(s):  
Optical Fiber ◽  
Glass Fiber ◽  
Glass Fibers ◽  
Air Entrainment ◽  
Injection Rate ◽  
Fiber Drawing ◽  
Cooling Effectiveness ◽  
Drawing Speed ◽  
Cooling Unit ◽  
Fiber Manufacturing

In an optical fiber manufacturing process, glass fibers drawn from the heated silica preform in the furnace should be sufficiently cooled down close to ambient temperature. As the fiber drawing speed continues to increase for better manufacturing productivity, the glass fiber cooling becomes more difficult and the use of helium injection into the glass fiber cooling unit is required to greatly enhance the fiber cooling effectiveness. The present study numerically simulates the flowfield and heat transfer phenomena on the glass fiber cooling in order to investigate the effects of helium injection and fiber drawing speed on the fiber cooling effectiveness of glass cooling unit. The results found that the amount of air entrainment at the unit inlet is the significant factor that decides the cooling effectiveness by significantly lowering the helium purity in cooling gas. Also, at a given fiber drawing speed, there exists a critical helium injection rate and the fiber cooling does not improve any more, even if the helium injection rate increases above this critical value.

Thermal Transport and Flow in High-Speed Optical Fiber Drawing

1998 ◽  
Vol 120 (4) ◽  
pp. 916-930 ◽  
Author(s):  
Zhilong Yin ◽  
Y. Jaluria
Keyword(s):  
Optical Fiber ◽  
Thermal Transport ◽  
High Speed ◽  
Radiative Transport ◽  
Gas Velocity ◽  
Furnace Temperature ◽  
Fiber Drawing ◽  
Zonal Method ◽  
Optical Fiber Drawing ◽  
Purge Gas

The thermal transport associated with optical fiber drawing at relatively high drawing speeds, ranging up to around 15 m/s, has been numerically investigated. A conjugate problem involving the glass and the purge gas regions is solved. The transport in the preform/fiber is coupled, through the boundary conditions, with that in the purge gas, which is used to provide an inert environment in the furnace. The zonal method, which models radiative transport between finite zones in a participating medium, has been employed to compute the radiative heat transfer in the glass. The flow of glass due to the drawing process is modeled with a prescribed free-surface neck-down profile. The numerical results are compared with the few that are available in the literature. The effects of important physical variables such as draw speed, purge gas velocity and properties, furnace temperature, and preform diameter on the flow and the thermal field are investigated. It is found that the fiber drawing speed, the furnace temperature, and the preform diameter have significant effects on the temperature field in the preform/fiber, while the effects of the purge gas velocity and properties are relatively minor. The overall heating of the preform/fiber is largely due to radiative transport in the furnace and the changes needed in the furnace temperature distribution in order to heat the glass to its softening point at high speeds are determined.

Effects of Air Entrainment on Glass Fiber Cooling with Helium Injection in Optical Fiber Drawing

2013 ◽  
Vol 19 (8) ◽  
pp. 2215-2219 ◽  
Author(s):  
Dongjoo Kim ◽  
Il-Seok Oh ◽  
Ho Sang Kwak ◽  
Kyoungjin Kim
Keyword(s):  
Optical Fiber ◽  
Glass Fiber ◽  
Air Entrainment ◽  
Fiber Drawing ◽  
Optical Fiber Drawing

Viscous Dissipation Effects on the Coating Resin Flow Characteristics in High-Speed Optical Fiber Coating Process

2015 ◽  
Vol 656-657 ◽  
pp. 496-499
Author(s):  
Kyoung Jin Kim
Keyword(s):  
Optical Fiber ◽  
High Speed ◽  
Viscous Heating ◽  
Coating Process ◽  
Operational Parameters ◽  
Fiber Drawing ◽  
Temperature Dependent Viscosity ◽  
Fiber Coating ◽  
Drawing Speed ◽  
Modern Mass

Since the fiber drawing speed continues to increase in the modern mass manufacturing of optical fibers, the effects of viscous heating on the coating liquid flow could be significant in the capillary coating die of optical fiber coating applicator. Present study investigates the viscous coating resin flows in the micron-sized channel of coating die with temperature dependent viscosity. The computational results find the substantial temperature increase near the die wall and plug-like velocity distribution due to localized viscous heating. Also, final coating thickness is affected by the change of coating die diameter when the fiber drawing speed is high. Thus, the design of glass fiber coating process at high drawing speed requires careful consideration of several key operational parameters.

Silica Preform Neck-Down Shape and Glass Fiber Drawing in Optical Fiber Manufacturing Process

2012 ◽  
Vol 488-489 ◽  
pp. 748-752
Author(s):  
Kyoung Jin Kim
Keyword(s):  
Optical Fiber ◽  
Glass Fiber ◽  
Cooling Rate ◽  
Momentum Balance ◽  
Maximum Temperature ◽  
Cylindrical Shape ◽  
Fiber Drawing ◽  
Thin Glass ◽  
High Fiber ◽  
Fiber Manufacturing

The glass fiber drawing from the silica preform in a draw furnace is one of the important processes in a mass manufacturing system of optical fiber. When a preform of cylindrical shape is fed and heated in draw furnace and very thin glass fiber is pulled from the softened preform by applying a proper amount of draw tension, the preform experiences a drastic diameter change or neck-down shape. In this paper, neck-down shape formation and glass fiber drawing in heated preform is numerically modeled into one-dimensional formulation of momentum balance in order to examine the effects of the silica preform temperature such as the maximum temperature of preform and the cooling rate of glass fiber at high fiber drawing speed. The results show the typical shape of preform neck-down and the draw tension which is comparable to the industry value of approximately 100 g. Also, it is found that the axial location of glass fiber re-solidification sensitively depends on the cooling rate, while the draw tension is insensitive to the cooling rate of glass fiber.

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