Bell Shaft Thermal Shield for Glass Tubing Stability

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Solution Overview

Problem

Glass tubing manufacturing processes face challenges in maintaining dimensional stability, leading to excessive wall thickness variations and increased siding loss due to thermal fluctuations and mechanical perturbations, resulting in discarded products and increased manufacturing costs.

Innovation Solution

The implementation of a bell assembly with a thermal shield and a bell shaft made from platinum or platinum alloys, featuring an insulation layer and a refractory material, which reduces temperature variations across the bell shaft, thereby minimizing deflection and maintaining dimensional stability during the glass tubing production process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional bell assemblies are used without thermal shields, then the manufacturing process is simpler, but dimensional stability of glass tubing deteriorates due to thermal fluctuations

Engineering Contradiction:
Improvedimensional stabilityVSAvoidbell assembly structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

A thermal shield made of refractory material is introduced as an intermediary component between the bell shaft and the molten glass. This shield mediates the thermal interaction, protecting the bell shaft from direct exposure to thermal fluctuations while maintaining the structural simplicity of the overall assembly.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The bell assembly employs composite construction by combining different materials - the bell shaft is made of metal while the thermal shield is made of refractory material. This composite approach allows each component to be optimized for its specific function: structural support and thermal protection respectively, thereby improving dimensional stability without excessive complexity.

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If thermal shields with insulation layers are added to reduce temperature variations, then dimensional stability improves, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvewall thickness uniformityVSAvoidthermal shield structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The thermal shield is applied locally around the bell shaft in the critical zone where thermal fluctuations have the greatest impact on dimensional stability. The shield extends only to the necessary height to protect the bell shaft, rather than enveloping the entire assembly, thus providing effective thermal protection with minimal added complexity.

Inventive Principle:
Principle #3Local quality

3Reliability

If platinum or platinum alloy materials are used for bell shaft and bell head, then resistance to thermal variation improves, but manufacturing cost increases

Engineering Contradiction:
Improvethermal dimensional stabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The material composition parameter is changed from conventional metals to platinum or platinum alloys, which have superior resistance to thermal variation and corrosion. This parameter change improves reliability and thermal dimensional stability, particularly in the bell shaft and bell head components that are most exposed to thermal and chemical environments.

Inventive Principle:
Principle #35Parameter changes

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 solution significantly reduces siding loss and maintains dimensional stability, enhancing manufacturing efficiency and reducing the incidence of inclusion defects in the glass tubing, thus improving overall production quality and reducing costs.

Implementation Method 1

a thermal shield positioned around at least a portion of the outer surface and extending through the glass delivery tank... The thermal shield may include an outer cladding and an insulation layer positioned between the outer cladding and the outer surface of the bell shaft

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 2

The insulation layer of the thermal shield may be made from a refractory material. The refractory material can be substantially free from organic compounds.

Methodology Applied
Scientific EffectRefractory material properties: Refractory Material

Implementation Method 3

The bell head and the bell shaft are made from platinum or a platinum alloy... undesired movement of bells within delivery orifices of glass delivery tanks due to thermal variation across the bell assembly apparatuses during glass tubing production is reduced

Methodology Applied
Scientific EffectThermal expansion resistance: Thermal Expansion

Data Source

PatentEP3429969B1Glass tubing manufacturing apparatus
Publication Date: 2021.12.22 CORNING INC
  • EP3429969B1 patent drawingFigure 1A~1B
  • EP3429969B1 patent drawingFigure 1C~1D
  • EP3429969B1 patent drawingFigure 2

AI summary

A bell assembly for a glass tubing manufacturing apparatus includes a bell head and a support connected to the bell head. The support includes a bell shaft with an inner bore and an outer surface, and a liner positioned in the inner bore of the bell shaft. A thermal shield extends along the outer surface of the bell shaft and reduces temperature variation across a width of the bell shaft during glass tubing manufacturing.