Optical fiber drawing die and drawing method therefor

Abstract

An optical fiber coating die is made such that an interfacial shear rate of the optical fiber to the resin coat is calculated in accordance with a pressure value of resin inside a coating cup, and the interfacial shear rate is in a range of −1.5×105 to 0 sec−1. Also, an optical fiber drawing die is made such that the interfacial shear rate of the optical fiber to the resin coat is calculated in accordance with a diameter of a coating resin, and the interfacial shear rate is in a range of range of −3×105 to 2×105 sec−1. By doing this, an optical fiber drawing die which can be used in an optical fiber drawing method so as to realize stable resin coating operation even in high-speed drawing operation and high productivity can be realized.

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       4 . An optical fiber drawing method for drawing an optical fiber using an optical fiber drawing apparatus, the optical fiber drawing apparatus comprising a first resin coating apparatus and a second resin coating apparatus, the first resin coating apparatus comprising a first optical fiber drawing die and a coating cup, the second resin coating apparatus comprising a second optical fiber drawing die, the method comprising the steps of: 
 forming the optical fiber comprising performing a drawing process on a raw material;    calculating an interfacial shear rate of the optical fiber to a first resin coat in accordance with a pressure value of a resin inside the coating cup;    forming a resin-coated optical fiber by applying the resin to the optical fiber using the first resin coating apparatus at the interfacial shear rate, the first optical fiber drawing die being characterized by the interfacial shear rate of the optical fiber to the resin being substantially in a range of −1.5×10 5  to 0 sec −1 ;    calculating a second interfacial shear rate of the optical fiber to a second resin coat in accordance with a diameter of the first resin coat; and    applying additional resin to the resin-coated optical fiber using the second resin coating apparatus, the second optical fiber drawing die being characterized by a second interfacial shear being substantially in a range of −3×10 5  to 2×10 5  sec −1 .    
   
   
       5 . An optical fiber drawing method for drawing an optical fiber using an optical fiber drawing apparatus, the optical fiber drawing apparatus comprising a resin coating apparatus for applying resin to an optical fiber using an optical fiber drawing die characterized by an interfacial shear rate of the optical fiber to a resin coat being substantially within a range of −1.5×10 5  to 0 sec −1  comprising the steps of: 
 forming the optical fiber by performing a drawing process on a raw material;    calculating the interfacial shear rate of the optical fiber to the resin coat in accordance with a pressure value of resin inside a coating cup; and    applying the resin coat using the optical fiber drawing die at the interfacial shear rate.    
   
   
       6 . A method for forming a resin coat on a resin-coated optical fiber using an optical fiber drawing die in a resin coating apparatus, the resin-coated optical fiber having a diameter of a coating resin, the optical fiber drawing die being characterized by an interfacial shear rate being substantially in a range of −3×10 5  to 2×10 5  sec −1 , the method comprising the steps of: 
 calculating the interfacial shear rate of the optical fiber to the resin coat in accordance with the diameter of the coating resin, and    applying the resin coat using the optical fiber drawing die at the interfacial shear rate.    
   
   
       7 . An optical fiber drawing die for use in a high drawing speed resin coating apparatus for forming a resin coat by applying a resin to an optical fiber formed by a drawing process, the apparatus comprising a resin coating cup, comprising: 
 a tapered section comprising at least one taper angle and a top face, the top face having an aperture through which the optical fiber is drawn, the resin from the resin coating cup being applied through the aperture in the top face while the optical fiber is drawn through, wherein the at least one taper angle is at least eight degrees;    an exit section adjacent the tapered section through which the optical fiber is drawn upon passing through the tapered section, the exit section comprising a cylindrical shape and an exit face, the cylindrical shape having a height and a diameter, the exit face having an exit aperture of dimension equal to the diameter, wherein the exit face is parallel to the top face; and    a length of the optical fiber drawing die extending from the top face to the exit face, wherein the length is at least eight times the diameter; and    wherein the at least one taper angle, the height, the diameter, and the length are dimensioned to produce an interfacial shear rate of the optical fiber to the resin coat in a range of −1.5×10 5  to 0 sec −1  for a drawing speed of the resin coating apparatus of at least 20 m/sec.    
   
   
       8 . The die of  claim 7 , wherein the interfacial shear rate is calculated in accordance with a pressure value of resin inside the resin coating cup.  
   
   
       9 . The die of  claim 7 , wherein the at least one taper angle is two taper angles, wherein one of the at least two taper angles is at least twenty degrees.  
   
   
       10 . An optical fiber drawing die for use in a high drawing speed resin coating apparatus for forming a resin coat by applying additional resin to a resin-coated optical fiber, comprising: 
 a tapered section comprising at least one taper angle and a top face, the top face having an aperture through which the resin-coated optical fiber is drawn, additional resin from the resin coating cup being applied through the aperture in the top face while the resin-coated optical fiber is drawn through;    an exit section adjacent the tapered section through which the resin-coated optical fiber is drawn upon passing through the tapered section, the exit section comprising a cylindrical shape and an exit face, the cylindrical shape having a height and a diameter, the exit face having an exit aperture of dimension equal to the diameter, wherein the exit face is parallel to the top face; and    a length of the optical fiber drawing die extending from the top face to the exit face, wherein the length is at least eight times the diameter; and    wherein the at least one taper angle, the height, the diameter, and the length are dimensioned to produce an interfacial shear rate of the resin-coated optical fiber to the resin coat in a range of −3×10 5  to 2×10 5  sec −1  for a drawing speed of the resin coating apparatus of at least 20 m/sec.    
   
   
       11 . The die of  claim 10 , wherein the interfacial shear rate is calculated in accordance with a diameter of a coating resin.  
   
   
       12 . The die of  claim 10 , wherien the at least one taper angle is one taper angle of at least eight degrees.  
   
   
       13 . The die of  claim 10 , wherein the at least one taper angle is two taper angles, wherein one of the two taper angles is at least five times greater than another one of the two taper angles, the greater taper angle being adjacent the exit section.