Chamfered Spacer Supports Core Rod in Glass Tube

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Solution Overview

Problem

The existing methods for producing elongated glass components, such as optical fibers, face challenges with weight-related deformation of the core rod during the manufacturing process, leading to inconsistent diameters and potential breakage, especially as the length increases, due to gravitational forces.

Innovation Solution

The method involves using a spacer that rotates into a vertical position within a chamfered region of the cladding tube to support the core rod, distributing the weight more evenly and preventing deformation, allowing for longer glass components to be manufactured without the need for core rods of specific diameters or complex machining.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the core rod is supported at the bottom by a support rod or holding ring, then the core rod is prevented from slipping out of position, but the core rod deforms under its own weight leading to inconsistent outer diameter

Engineering Contradiction:
Improvecore rod outer diameter consistencyVSAvoidcore rod position stability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The support function is segmented into multiple points along the cladding tube length. Instead of a single bottom support, multiple spacers are distributed at different positions to support the core rod at multiple locations, preventing both deformation and slippage simultaneously

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spacers are pre-positioned inside the cladding tube before the core rod is inserted. This preliminary placement ensures the core rod is supported at the correct positions from the beginning of the assembly process, preventing both deformation and position instability

Inventive Principle:
Principle #10Preliminary action

2Productivity

If the length of the core rod is increased to produce longer glass components, then the productivity is improved, but the weight-related deformation and breakage risk increases

Engineering Contradiction:
Improveglass component lengthVSAvoidcore rod resistance to deformation and breakage
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The support system is segmented into multiple spacers distributed along the length of the cladding tube. This segmentation provides frequent support points that prevent the core rod from sagging or breaking under its own weight, enabling production of longer glass components with improved productivity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spacing between support points is optimized based on the core rod length and material properties. By adjusting the spacer distribution parameters, the system maintains adequate support frequency even for very long core rods, preventing deformation and breakage while enabling higher productivity

Inventive Principle:
Principle #35Parameter changes

3Reliability

If a negative pressure is applied to the gap between the core rod and cladding tube, then the core rod is held in position against gravitational forces, but the maximum pressure difference limits the effectiveness for long core rods

Engineering Contradiction:
Improvecore rod position stabilityVSAvoidpressure difference capability
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The single negative pressure system is segmented into multiple local support zones created by spacers distributed along the cladding tube. Each spacer creates a local support point that prevents core rod slippage without requiring high negative pressure, overcoming the pressure difference limitation for long core rods

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spacers act as intermediary elements between the core rod and cladding tube, providing mechanical support at multiple positions. This intermediary support system eliminates the need for high negative pressure by distributing the holding function across multiple physical contact points

Inventive Principle:
Principle #24Intermediary (Mediator)

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 approach reduces the risk of core rod deformation and breakage, maintains consistent dimensions, and enables the production of longer glass components with improved reliability and reduced manufacturing costs by evenly distributing the weight along the cladding tube.

Implementation Method 1

weight-related deformation of the core rod during the manufacturing process, leading to inconsistent diameters and potential breakage, especially as the length increases, due to gravitational forces

Methodology Applied
Scientific EffectGravitation: Gravitation

Implementation Method 2

The cladding tube and core rod are then heated while maintaining the vacuum, resulting in the cladding tube collapsing around the core rod

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 3

application of a negative pressure to the gap between the outer diameter of the core rod and the inner diameter of the cladding tube can counteract the gravitational forces acting on the core rod

Methodology Applied
Scientific EffectVacuum: Vacuum

Data Source

PatentEP3303234B1Method for inserting a core rod into an outer cladding tube with spacer
Publication Date: 2020.08.05 HERAEUS QUARZGLAS GMBH & CO KG
  • EP3303234B1 patent drawingFigure 1A~1D
  • EP3303234B1 patent drawingFigure 1E~2B
  • EP3303234B1 patent drawingFigure 3A~3D

AI summary

Methods for producing glass components and obtainted glass component, e.g. optical fiber preform. A method includes providing a cladding tube (110) with a longitudinal axis including a first and a second bore separated by a chamfered region (114); inserting a spacer (120) into the first bore; inserting a rod (130) into the first bore (116); moving the spacer (120) into the chamfered section (114), causing the spacer (120) to rotate within the chamfered region (114); and rotating the cladding tube (110) into a vertical orientation, whereby the spacer (120) is prevented from entering the second bore (118) and supports the rod (130). Each portion of the chamfered region has a height perpendicular to the longitudinal axis greater than the height of the second bore. The spacer has a length parallel to the longitudinal axis greater than the height of the second bore but less the distance between the deepest point of the bottom of the chamfered region and an intersection of the top of the chamfered region and the first bore.