Slit Heater Geometry for Glass Preform Furnace Arching
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Solution Overview
Problem
Aching occurs between the susceptor and the slit heater, or between the slit heater and the conductive member in glass preform heating furnaces, particularly when using inert gases like Ar, leading to improper heating and potential furnace damage.
Innovation Solution
The slit width of the slit heater is set to a specific ratio relative to the space between the slit heater and the susceptor, ensuring the maximum electric field in the slit space is greater than or equal to the electric field between the slit heater and the conductive member, effectively suppressing arching by increasing the slit width to 8×(D/N) or more for single-phase and 9×(D/N) or more for three-phase configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the power (voltage) applied to the cylindrical heater is raised to heat the furnace to a predetermined temperature, then the heating efficiency is improved, but arching occurs between the susceptor and the heater or between the heater and the conductive member
Solution Approach 1:
The patent changes the geometric parameters of the heater structure, specifically the slit width, to control the electric field distribution. By setting the slit width to 8×(D/N) or more (where D is the space between heater and susceptor, N is the number of slits), the maximum electric field in the slit space is increased to be greater than or equal to the electric field between the heater and conductive member, thereby suppressing arching while maintaining heating effectiveness
2Reliability
If the slit width of the slit heater is increased to suppress arching, then the reliability is improved, but the heating efficiency may be reduced
Solution Approach 1:
The patent optimizes the slit width parameter to a specific range (8×(D/N) or more) that balances arching suppression with heating efficiency. This parameter setting ensures that the electric field in the slit space is sufficiently strong to prevent discharge while maintaining adequate thermal radiation for effective heating
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively suppresses arching, ensuring stable heating and preventing furnace damage, allowing for successful optical fiber drawing by maintaining a sufficient slit width to reduce electric field strength and prevent discharge.
Implementation Method 1
a cylindrical heater (4) for heating is disposed so as to enclose a susceptor (3)
Implementation Method 2
the cylindrical heater 4 is enclosed with an insulator 5 so that the heat of the cylindrical heater 4 is not dissipated to the outside
Implementation Method 3
a cooling water passage or the like is provided so that the furnace body can be cooled
Implementation Method 4
an inert gas or the like, such as helium (He) gas, argon (Ar) gas, or nitrogen (N2) gas, is supplied into the furnace body 6 to prevent carbon components, such as the cylindrical heater 4 and the insulator 5, from being degraded due to oxidation
Data Source
AI summary
The present invention provides a glass preform heating furnace in which the occurrence of arching is suppressed. The glass preform heating furnace is equipped with a susceptor (3); a slit heater (4); an insulator; and a furnace body, wherein, in the case that the space between the slit heater (4) and the susceptor or between the slit heater (4) and the conductive member closest to the slit heater is D, that the maximum value of the electric field in this space is E1, that the number of the slits in the slit heater is N, that the slit width of the slit heater is S, and that the maximum value of the electric field in the slit space is E2, the values of D, N and S are set so that E1≧E2 is established.