Segmented Supplying Tube for Sheet Glass Manufacturing
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Solution Overview
Problem
Conventional methods for manufacturing sheet glass, such as the overflow down-draw process, face issues with rapid changes in molten glass flow rate and viscosity, leading to devitrification and bubble generation due to reduced or stopped flow speeds, which result in reduced quality and yield.
Innovation Solution
A supplying tube with a small diameter tube portion at the upstream, an expanded diameter tube portion in the middle, and a large diameter tube portion at the downstream, where the molten glass flows through the expanded tube portion to maintain a stable flow rate and reduce contact with platinum, thereby minimizing devitrification and bubble generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the supplying tube has a constant diameter, then the structure is simple, but the flow rate changes rapidly when temperature changes occur
Solution Approach 1:
The supplying tube is divided into three distinct sections with different diameters: a small diameter upstream section, an intermediate section with gradually expanding diameter, and a large diameter downstream section. This segmentation allows each section to serve a specific function in maintaining stable flow rate while managing the complexity of temperature control during sheet glass manufacturing.
2Temperature
If the temperature near the forming furnace is changed to adjust viscosity, then the viscosity can be adjusted appropriately, but the flow rate changes rapidly and takes long to reach steady state
Solution Approach 1:
Temperature control is applied locally to different sections of the supplying tube rather than uniformly. The small diameter upstream section and large diameter downstream section can have different temperature profiles, allowing viscosity adjustment without causing rapid flow rate changes throughout the entire tube. This local quality approach enables temperature adjustment while maintaining flow stability and reducing time to reach steady state.
3Duration of action of moving object
If the molten glass flow speed reduces or stops, then the contact time with platinum increases, but devitrification and bubble generation occur
Solution Approach 1:
The intermediate section of the supplying tube features a gradually expanding diameter rather than an abrupt change, creating a smooth curved transition. This curvature prevents flow separation and maintains continuous molten glass flow through the transition zone, ensuring adequate contact time with platinum for quality control while preventing devitrification and bubble generation that would occur with stagnant flow.
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 configuration stabilizes the flow rate and viscosity of molten glass, reducing the likelihood of devitrification and bubble generation, resulting in improved quality and yield of sheet glass, especially during temperature changes near the forming furnace.
Implementation Method 1
the molten glass passes through the expanded tube portion, thereby generating a flow that moves along the inner surface of the tube
Implementation Method 2
the flow rate of the molten glass supplied to the forming furnace is controlled by the viscosity of the molten glass in the small diameter tube portion
Data Source
AI summary
A supplying tube for a molten glass, which is placed in a downstream end portion of a supplying passage directing the molten glass flowing out of a melting furnace to a forming vessel in a forming furnace, has a small diameter tube portion which has a small flow passage area and is provided at an upstream side, and a large diameter tube portion which is provided at a downstream side of the small diameter tube portion and has a large flow passage area. An expanded diameter tube portion of which flow passage area gradually expands toward the downstream side is interposed between the small diameter tube portion and the large diameter tube portion. The small diameter tube portion, the expanded diameter tube portion, and the large diameter tube portion may be integrally and continuously connected to one another.