Silica Glass Block Manufacturing Bubble Reduction

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Solution Overview

Problem

Conventional methods for manufacturing large silica glass blocks result in the formation of air bubbles due to unsatisfactory release of moisture and gases, leading to reduced quality and yield, and contamination from refractory bricks used in the furnace.

Innovation Solution

The method involves using silica raw material powder with specific purity and particle size, applying vibration to increase packing density, and employing a silica glass plate or molybdenum sheet to prevent direct contact with refractory bricks, along with a controlled furnace temperature and atmosphere program to remove moisture and gases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If silica raw material powder is directly charged into the fusing furnace through a raw material drum, then the charging process is simple, but multiple layers (stratified bubbles) are formed in the silica glass block

Engineering Contradiction:
Improvecharging process simplicityVSAvoidbubble formation in silica glass block
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

A hopper is introduced as an intermediary device between the raw material drum and the fusing furnace. The hopper receives powder from the drum and discharges it through a controlled outlet, preventing the powder from being blown about during charging. This intermediary structure eliminates stratified bubble formation while maintaining manufacturing simplicity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If the silica raw material powder is charged without compacting treatment, then the charging process is simple, but bubbles are directly formed from gaps in the powder

Engineering Contradiction:
Improvecharging process simplicityVSAvoidbubble formation from powder gaps
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

A compacting treatment is performed on the silica raw material powder before charging it into the fusing furnace. This preliminary action eliminates gaps between powder particles, preventing bubble formation during the subsequent melting process. The compacting is done using a simple pressing mechanism that maintains ease of manufacture while significantly improving manufacturing precision.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If the temperature is raised to 1750°C or higher in a single action to fuse the silica raw material powder, then the fusing process is efficient, but moisture and gases are not satisfactorily released and remain as air bubbles

Engineering Contradiction:
Improvefusing process efficiencyVSAvoidair bubble removal
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The fusing process is segmented into multiple stages with progressively increasing temperatures. The first stage removes moisture and gases at lower temperatures, while subsequent stages complete the fusing at higher temperatures. This segmentation allows efficient bubble removal without sacrificing overall fusing efficiency, as each stage is optimized for its specific purpose.

Inventive Principle:
Principle #1Segmentation

4Manufacturing precision

If the silica raw material powder is charged using a hopper with controlled discharge, then stratified bubble formation is prevented, but the charging process becomes more complex

Engineering Contradiction:
Improveprevention of stratified bubblesVSAvoidcharging device structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The hopper is designed with a localized controlled discharge outlet at its bottom, while the rest of the structure remains simple. This local quality enhancement (the controlled outlet) provides the necessary precision to prevent stratified bubble formation without requiring complex modifications to the entire charging device. The simplicity of the overall structure is maintained while achieving the desired manufacturing precision.

Inventive Principle:
Principle #3Local quality

5Manufacturing precision

If the silica raw material powder is compacted before charging, then bubble formation from powder gaps is prevented, but the manufacturing process becomes more complex

Engineering Contradiction:
Improveprevention of bubbles from powder gapsVSAvoidpowder compacting device
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The compacting device is designed with a simple pressing mechanism that applies localized pressure to the powder. Only the essential compacting function is implemented without complex auxiliary systems. This local quality approach (simple pressing) achieves the necessary prevention of bubble formation while keeping the device complexity minimal and the manufacturing process straightforward.

Inventive Principle:
Principle #3Local quality

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 significantly reduces bubbles within the silica glass block, improves its quality, prevents contamination, and enhances the yield by ensuring complete removal of impurities and gases.

Implementation Method 1

means for applying vibration to the silica raw material powder packed into said receptacle to raise the packing density

Methodology Applied
Scientific EffectVibration: Vibration

Implementation Method 2

heat 16 is applied by heating means 14 provided in an upper portion of the fusing furnace 10 to fuse the silica raw material powder 12

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 3

to fuse the silica raw material powder 12... A thus-obtained fused-state silica glass melt 12a

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 4

The fused-state silica glass melt 12a is cooled to produce a silica glass

Methodology Applied
Scientific EffectCooling: Cooling

Data Source

PatentEP2050724B1Method of manufacturing a silica glass block
Publication Date: 2014.08.27 HERAEUS QUARZGLAS GMBH & CO KG
  • EP2050724B1 patent drawingFigure 1
  • EP2050724B1 patent drawingFigure 2(a)~2(c)
  • EP2050724B1 patent drawingFigure 3(a)~3(b)

AI summary

The present invention refers to a method for manufacturing a silica glass block in which, by markedly reducing the bubbles within the silica glass block, the quality of a silica glass block can be improved, contamination of the silica glass block can be prevented, and the yield of the silica glass block can be improved. The method comprises: a preparing step for preparing a natural or synthetic silica raw material powder (12); a packing step for packing the silica raw material powder into a glass fusing furnace (10); a preheat treating step for preheat treating the silica raw material powder (12) packed into the fusing furnace (10); a fusing step for heating and fusing the heat preheat-treated silica raw material powder (12); and a cooling step for cooling a silica glass melt fused in the fusing furnace, and is characterized in that the silica raw material powder packed into the fusing furnace is closely packed in the packing step, to a packing density of no less than 1.4 g/cm3 and no more than 1.6 g/cm3, and an evacuation and a rare gas or H2 gas introduction treatment is performed in the preheat treating step.