Glass Parison Low-Temperature Blowing for Uniform Container Walls
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Solution Overview
Problem
The standard container-forming process for soda-lime-silica glass results in inconsistent wall thickness and shape irregularities due to significant temperature gradients and rapid viscosity changes during the transformation of a glass gob to a parison and subsequent blowing into a container, leading to issues like cracked finishes and out-of-round shapes.
Innovation Solution
A low-temperature blowing process is employed where the expandable blow portion of the parison is brought to a forming viscosity between 107.5 Pa·s and 105.5 Pa·s and an isoviscous state, with temperature gradients across the tubular wall translating to a maximum viscosity difference of 102 Pa·s or less, allowing for controlled blow molding into a glass container.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional high-temperature blowing process is used, then glass can be easily formed, but temperature gradients and viscosity changes cause inconsistent wall thickness and shape irregularities
Solution Approach 1:
The patent applies parameter changes by reducing the blowing temperature from conventional high temperatures to a lower range of 650-750°C. This temperature reduction fundamentally changes the glass viscosity characteristics, allowing the glass to maintain more stable dimensional properties during the blowing process. The lower temperature parameter prevents excessive viscosity changes and temperature gradients that cause wall thickness inconsistency and shape irregularities in conventional processes.
Solution Approach 2:
The patent implements preliminary action by pre-heating the parison to a controlled temperature range (650-750°C) before the blowing operation. This preliminary thermal conditioning ensures the glass reaches an optimal viscosity state prior to forming, creating uniform temperature distribution throughout the parison wall. This pre-conditioning prevents sudden temperature gradients during blowing that would otherwise cause wall thickness variation and shape defects.
2Productivity
If rapid blowing is used to increase productivity, then production speed increases, but temperature gradients cause cracked finishes and out-of-round shapes
Solution Approach 1:
The patent changes the temperature parameter to a lower range (650-750°C) where glass viscosity is more stable and less sensitive to rapid deformation. This parameter modification allows the glass to accommodate faster blowing rates without developing excessive temperature gradients or undergoing uncontrollable viscosity changes, thereby preventing cracked finishes and out-of-round shapes even at increased production speeds.
3Ease of manufacture
If high-temperature processing is used, then glass flow is easier, but viscosity changes lead to process instability and container variances
Solution Approach 1:
The patent applies parameter changes by operating at a lower temperature range (650-750°C) where the glass viscosity is optimized for dimensional stability. At this lower temperature, the glass maintains sufficient formability while exhibiting reduced sensitivity to viscosity changes during the forming process. This parameter adjustment eliminates the trade-off between ease of manufacture and dimensional consistency that plagues high-temperature processing.
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 process instability and container variances by ensuring uniform glass flow and temperature consistency, minimizing defects such as cracked finishes and irregular shapes, while maintaining process stability and equipment precision.
Implementation Method 1
the expandable blow portion of the parison has been brought to a forming viscosity between 107.5 Pa·s and 105.5 Pa·s and also to an isoviscous state
Implementation Method 2
introducing a compressed gas into an interior parison cavity to thereby outwardly expand the expandable blow portion of the parison
Data Source
AI summary
A method of forming a glass container includes providing a glass parison having a tubular wall that includes an inside surface, which defines an interior parison cavity open at one axial end of the tubular wall, and an outside surface. The tubular wall includes an expandable blow portion that has a forming viscosity between 107.5 Pa·s and 105.5 Pa·s and is also in an isoviscous state. The glass parison is blow molded into a glass container by introducing a compressed gas into the interior parison cavity to thereby cause the expandable blow portion of the tubular wall to expand outwardly into a portion of a wall that defines the glass container.