Optical Fiber Preform Joint Structure to Prevent Rod Separation
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Solution Overview
Problem
The existing methods for manufacturing optical fiber glass preforms are prone to separation at the joint between the starting rod and the dummy glass due to applied loads during heating, especially when fluorine is doped in the starting rod, leading to potential damage.
Innovation Solution
The starting rod is fitted with a dummy glass that is integrally joined, with the dummy glass fitted into the starting rod to form a joint that minimizes separation, and the joint is processed to ensure a uniform stress distribution and reduce air bubbles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the starting rod and dummy glass are joined by conventional methods (pressing and reciprocating), then the joint can be formed, but separation occurs in the vicinity of the joint when load is applied during heating
Solution Approach 1:
The dummy glass is fitted into the starting rod, creating a nested structure where one component is inserted into the other. This nesting arrangement provides mechanical interlocking and distributes stress more effectively, preventing separation when load is applied during the heating process.
Solution Approach 2:
The starting rod and dummy glass are joined before the heating process begins. By performing the joining action in advance, the joint is already formed and stabilized before thermal loads are applied, preventing separation that would occur if joining were attempted during heating.
2Manufacturing precision
If fluorine is doped in the starting rod to form depressed portion, then the refractive index is reduced, but separation is likely to occur in the vicinity of the joint
Solution Approach 1:
The nested fitting structure provides mechanical reinforcement at the joint, compensating for the potential weakness introduced by fluorine doping. The interlocking geometry distributes stresses that would otherwise concentrate at the doped region, maintaining joint reliability despite the presence of fluorine.
3Productivity
If the dummy glass is hanged down and heated in a state where load is applied, then the optical fiber glass preform can be manufactured, but separation occurs at the joint
Solution Approach 1:
The joining of the dummy glass to the starting rod is performed as a preliminary action before the heating and load application steps. This ensures the joint is already formed and structurally sound before thermal and mechanical loads are applied during the manufacturing process, preventing separation while maintaining productivity.
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 method significantly reduces the likelihood of separation at the joint, even under applied loads, enhancing the stability and integrity of the optical fiber glass preform.
Implementation Method 1
an end face of the dummy glass (1) and an end face of the starting rod (2) are welded to each other
Implementation Method 2
a processing iron 8 is brought into contact with a connection portion 7 to level a large-diameter portion 7
Data Source
AI summary
Provided is an optical fiber glass preform in which a starting rod and a dummy glass are hardly separated from each other, and a method for manufacturing the glass preform. In the optical fiber glass preform, the dummy glass is fitted into one end of the starting rod, and a part of the dummy glass and the starting rod are surrounded by a clad glass. In the manufacturing method, at the time of connecting the starting rod and the dummy glass, a shape is adjusted in such a manner that an iron is brought into contact with a connection portion and is moved from a starting rod side toward a dummy glass side with appliance of a load.