Hollow Quartz Glass Ingot Cooling for Crack-Free Cutting

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Solution Overview

Problem

Continuous production of hollow quartz-glass ingots with large outside diameters and thick walls faces challenges in cracking during cutting, as existing methods fail to achieve homogeneous cooling, leading to elastic stress and subsequent cracking.

Innovation Solution

A continuous method involving active cooling of both internal and external surfaces of the ingot, using cooling gases, fluids, and radiation to reduce temperature differences and alleviate elastic stress, allowing for on-line cutting without severe cracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If continuous production of hollow quartz-glass ingots with large outside diameters and thick walls is implemented, then productivity and economic efficiency are improved, but cracking occurs during cutting due to elastic stress from non-uniform cooling

Engineering Contradiction:
Improvecontinuous production capabilityVSAvoidcrack-free cutting
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The cooling process is segmented into multiple independent cooling zones (first cooling zone with first cooling means, second cooling zone with second cooling means) that can be controlled separately. This allows different parts of the ingot to be cooled at different rates and to different temperatures, enabling the outer surface to be cooled more rapidly than the inner surface, thereby reducing elastic stress and preventing cracking during cutting while maintaining continuous production

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different cooling intensities are applied to different locations on the ingot surface. The first cooling means and second cooling means provide localized cooling zones with varying cooling capacities, creating non-uniform cooling patterns that reduce temperature gradients and elastic stress in critical areas, preventing cracks during cutting while maintaining high productivity

Inventive Principle:
Principle #3Local quality

2Productivity

If the ingot is cooled rapidly to increase production speed, then productivity is improved, but elastic stress increases causing cracking during cutting

Engineering Contradiction:
Improvecooling speedVSAvoidresistance to cracking
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The cooling system is divided into multiple independent cooling zones with controllable cooling intensities. By segmenting the cooling process, the system can apply moderate cooling rates in certain zones while maintaining overall high productivity, preventing excessive elastic stress accumulation that would cause cracking

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cooling means are designed to be adjustable and controllable during the cooling process. The cooling intensity can be dynamically modified to optimize the balance between cooling speed and stress reduction, allowing the system to adapt cooling rates to prevent cracking while maintaining efficient production

Inventive Principle:
Principle #15Dynamics

3Reliability

If batch processes are used to avoid cracking, then reliability is improved, but productivity and economic efficiency deteriorate

Engineering Contradiction:
Improvecrack-free productionVSAvoidcontinuous operation capability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The continuous production process is divided into multiple cooling zones that can be independently controlled, allowing each zone to manage stress development locally. This segmentation enables continuous operation while preventing the cracking that previously required batch processing, thereby maintaining both reliability and productivity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cooling process is designed as a continuous operation with multiple cooling zones working simultaneously along the ingot length. This continuous cooling action eliminates the need to stop production for batch processing, maintaining uninterrupted manufacturing while preventing cracks through controlled stress management

Inventive Principle:
Principle #20Continuity of useful action

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

The method effectively reduces elastic stress in the ingot, minimizing or eliminating cracking during cutting, enabling the economical production of large diameter, thick-walled hollow quartz-glass ingots with reduced tensile stress.

Implementation Method 1

cooling of the outer surface of the hollow quartz-glass ingot by convection and/or radiation

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

cooling of the outer surface of the hollow quartz-glass ingot by convection and/or radiation

Methodology Applied
Scientific EffectRadiation: Radiation

Data Source

PatentEP3656746B1Method and apparatus for cutting a hollow quartz glass ingot
Publication Date: 2024.06.05 HERAEUS QUARTZ UK LTD
  • EP3656746B1 patent drawingFigure 1
  • EP3656746B1 patent drawingFigure 2(A)~2(B)
  • EP3656746B1 patent drawingFigure 2(C)~2(D)

AI summary

The present invention relates to a continuous method for the production of hollow quartz-glass ingots 18 and an apparatus for said method, whereby the hollow quartz-glass ingots are drawn then actively cooled on the internal surface e.g. with water sprays 33 before being cut at cutting station 20.