Back to results
US 5,106,400 AGranted
Casting core/clad glass preforms method and apparatus
AssigneeCorning Incorporated
InventorPaul A. Tick
Life of this patent
Estimating the term…
Abstract
Disclosed is a method of forming a glass preform from core and cladding glasses having low liquidus viscosities and narrow working ranges. A tube of liquid core glass is vertically situated in a vessel of liquid cladding glass. The tube extends to the bottom of the vessel where there is a stopper for preventing leakage of core glass. While both core and cladding glasses are at a temperature just above the liquidus temperature, the vessel is lowered into a coolant bath, thereby causing core glass to flow into the region vacated by the tube. The rate of withdrawing the tube from the vessel is sufficiently slow to provide laminar flow and yet fast enough to permit the resultant liquid core/clad composite to freeze before mixing occurs.
Claims35
A method of forming a glass optical fiber comprising the steps of
- flowing a column of liquid core glass into a cylindrically-shaped quantity of liquid cladding glass while both core and cladding glasses are at a temperature above their liquidus temperatures, said glasses being readily devitrifiable glasses selected from the group consisting of halides, chalcogenides, oxy-halides, lead silicates, phosphates and borates, which exhibit narrow working ranges, whereby a change in temperature of only a few degrees Centigrade is sufficient to change the glass from the liquid to the solid state, said cylindrically-shaped quantity having a given cross-sectional area,
- freezing said core and cladding glasses before the onset of crystallization and before said streams begin to mix, thereby forming a preform, the cross-sectional area of which is substantially equal to that of said given cross-sectional area, and thereafter
- drawing a fiber from said preform.
A method of forming a glass preform comprising the steps of
- flowing a column of liquid core glass into a quantity of liquid cladding glass while both core and cladding glasses are at a temperature above their liquidus temperatures, the step of flowing comprising providing a composite structure comprising a vessel having a tube therein, said vessel having a closed base at one end and an opening at the opposite end, said tube having first and second ends, said first tube end lying adjacent said base, said tube containing liquid core glass, a region within said vessel surrounding said tube containing liquid cladding glass,
- withdrawing said tube from said vessel, whereby incremental liquid preform regions are formed, each liquid preform region comprising liquid core glass surrounded by liquid cladding glass, the interface between said liquid core and cladding glass in said liquid preform region being well defined, the first formed liquid preform region being formed adjacent said base, each subsequently formed liquid preform region being formed on that side of the previously formed liquid region toward said opening, and
- freezing said core and cladding glasses before the onset of crystallization and before said streams begin to mix, the step of freezing comprising cooling that portion of said vessel adjacent said first formed incremental liquid preform region before said core and cladding glasses mix, and thereafter, cooling that portion of said vessel adjacent subsequently formed incremental liquid preform regions before the liquid core and cladding glasses of said subsequently formed liquid preform regions mix.
A method of forming a glass preform comprising the steps of
- disposing a column of liquid core glass in a vessel of liquid cladding glass having means for separating said core and cladding glasses,
- withdrawing said separating means from said vessel, whereby core glass comes into contact with said cladding glass, and
- freezing said core and cladding glasses.
A method of forming a glass article comprising the steps of
- providing a vessel having a base at one end and an opening at the opposite end, and a tube having first and second ends, said first tube end lying adjacent said base and said second tube end extending beyond said vessel opening, first and second glass melting containers being disposed in close proximity to said vessel,
- loading core glass into said first container,
- loading cladding glass into said second container,
- simultaneously positioning said vessel and said containers in a furnace, the temperature of which is sufficient to melt said core and cladding glasses in said containers,
- flowing said core and cladding glasses from said first and second containers into said tube and vessel, respectively,
- withdrawing said vessel from said furnace, said tube remaining stationary in said furnace, whereby a column of said liquid core glass flows from said first end of said tube and into said cladding glass,
- freezing said core and cladding glasses in said vessel to form a preform, and
- forming an elongated article from said preform.
5 more elements
Apparatus for forming a glass preform comprising
- a cladding glass vessel having a base at one end and an opening at the opposite end,
- means for heating said vessel,
- separating means in said vessel for retaining a column of liquid core glass and separating said core glass from said cladding glass,
- means for withdrawing said retaining means from said vessel, thereby gradually forming a liquid glass preform, and
- means for cooling said liquid preform.
2 more elements
Apparatus for forming a glass preform comprising
- a furnace having an opening in at least one end thereof,
- a cladding glass vessel disposed in said furnace, said vessel having a base at one end and an opening at the opposite end,
- a core glass tube having first and second ends, at least a portion of said tube disposed in said vessel with said second end of said tube adjacent said vessel base,
- means for preventing the flow of glass from the second end of said tube into said vessel when said second end of said tube is adjacent said vessel base,
- a container of coolant adjacent that end of said furnace having said opening,
- means for maintaining said tube in a stationary position in said furnace, and
- means for withdrawing said vessel from said furnace and immersing said vessel in said coolant, whereby a column of said liquid core glass flows from said tube and into said cladding glass, the composite of said liquid cladding and core glasses being frozen to form said preform.
4 more elements
Dependencies are inferred from the claim text.