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.

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.

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

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.

A Computational Investigation of Thermal Effects on Resin Coating Flows in an Optical Fiber Drawing System

2011 ◽  
Vol 110-116 ◽  
pp. 1080-1086
Author(s):  
Kyoung Jin Kim ◽  
Ho Sang Kwak ◽  
Jin Su Choi
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Thermal Effects ◽  
Resin Flow ◽  
Fiber Drawing ◽  
Coating Flows ◽  
Drawing Speed ◽  
Drawing System ◽  
Optical Fiber Drawing ◽  
Fiber Manufacturing

In manufacturing optical fibers, there has been intense research efforts of continually increasing fiber drawing speed to improve productivity. However, higher speed fiber drawing poses new challenge in many areas of optical fiber manufacturing. In this paper, thermal effects on coating resin flow in an unpressurized coating applicator are studied numerically. Present simulation results found that higher fiber drawing speed leads to severe viscous heating in coating resin flow and significant increase of resin temperature, which in turn leads to substantial viscosity decrease. These thermal effects profoundly alter the resin flow patterns and velocity profiles in the coating die and they should be considered in controlling the final coating thickness.

A Numerical Investigation of the Free Surface Flow During Optical Fiber Coating Process

2001 ◽  
Author(s):  
C. S. L. Liu ◽  
S. H.-K. Lee
Keyword(s):  
Contact Angle ◽  
Free Surface ◽  
Optical Fiber ◽  
Dynamic Contact Angle ◽  
Air Entrainment ◽  
Dynamic Contact ◽  
Coating Process ◽  
Coating Quality ◽  
Fiber Coating ◽  
Drawing Speed

Abstract Optical fiber has increasingly played a crucial role in the information transmission area nowadays. The elevated demand makes it necessary to manufacture high quality light-guide fibers that have proper mechanical properties to endure the stresses induced during installations and operations. Optical fiber coating process provides a protection layer to shield the fiber from surface abrasion and also to increase the fiber’s tensile strength. However, there are problems encountered during this process which reduce the coating quality. One of the major problems is air entrainment, which may lead to eccentrical or incomplete coating. Apparently, it is of great interest to study this problem to improve the coating quality. Many experimental studies have been performed on the dynamic contact angle, air entrainment velocity and their correlation with various parameters, such as the viscosity and the surface tension of coating materials, fiber drawing speed, etc. Nevertheless, how the coating flow affects the upper meniscus (directly related with dynamic contact angle and air entrainment) has not been intensively studied. Understanding of the effects is essential to improve the coating quality. To fulfill this requirement, the present work focused on investigating the relation of upper meniscus and fiber drawing speed. This is just the first part of the serial study on the optical fiber coating process. Firstly, a numerical code was developed with finite volume formulation. The results showed that the code had the capacity to deal with this free surface fluid flow problem. The simulated free surface shape was validated with experimental data available. The trend of the upper meniscus shape and dynamic contact angle developments at high drawing velocity was simulated. The results showed, as expected, that the dynamic contact angle would approach 180° with the increase of the fiber-drawing speed.

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
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