Pressed 3D Glass Molding With Carbon Soot Lubrication
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Solution Overview
Problem
Forming thin, three-dimensional glass articles via pressing is challenging due to increased friction and viscosity when molten glass contacts tooling, requiring high pressing forces that can lead to defects like cracks, and process adjustments are impracticable.
Innovation Solution
A method and system that form a continuous layer of carbon soot on mold assembly surfaces via thermal decomposition of hydrocarbons to reduce friction, allowing for lower pressing forces and forming thin, 3D-shaped glass articles with varying thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If pressing force is increased to form thin glass articles, then the glass article can be formed with desired thickness, but the glass article develops defects such as cracks or microcracks
Solution Approach 1:
A solid lubricant layer is introduced as an intermediary substance between the glass and the press tooling surfaces. This lubricant layer reduces friction and allows the glass to be pressed to thinner dimensions without developing cracks or microcracks, thereby resolving the contradiction between achieving thin thickness and maintaining defect-free quality
Solution Approach 2:
The friction conditions at the glass-tooling interface are changed by applying a solid lubricant. This parameter change in surface properties enables lower pressing forces to achieve the same forming result, preventing glass defects while maintaining the ability to form thin articles
2Length of moving object
If pressing force is increased to overcome friction, then thin glass articles can be formed, but the pressing force significantly increases beyond practical limits
Solution Approach 1:
The solid lubricant acts as a mediator that reduces the frictional resistance between glass and tooling. This intermediary layer enables thin glass articles to be formed with significantly reduced pressing forces, making the process practically feasible
Solution Approach 2:
The high mechanical pressing force required to overcome friction is replaced by a chemical/physical solution - the solid lubricant reduces friction at the molecular level, substituting mechanical force with a lubrication mechanism
3Force
If glass viscosity is decreased to improve flow, then glass can be pressed more easily, but glass viscosity increases rapidly when cooled by contact with press tooling
Solution Approach 1:
The solid lubricant layer serves as a thermal barrier that reduces heat transfer from the glass to the tooling. This maintains higher glass temperature and lower viscosity during pressing, improving flow characteristics while preventing rapid viscosity increase from cooling
Solution Approach 2:
The solid lubricant is applied beforehand to the tooling surfaces to create a protective layer that prevents direct thermal contact between glass and tooling, cushioning against the rapid cooling effect that would increase viscosity
4Force
If time between gob formation and pressing is decreased to maintain low viscosity, then glass flow is improved, but process control becomes more difficult
Solution Approach 1:
The solid lubricant layer allows extended time between gob formation and pressing by maintaining favorable friction conditions throughout. This intermediary enables process flexibility without compromising glass flow or requiring precise timing control
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 significantly reduces pressing forces needed, enabling the formation of thin, 3D-shaped glass articles with large thickness variations and small curvatures, extending the process window and ensuring defect-free production.
Implementation Method 1
modifying the friction conditions between the gob and the press tooling by forming a continuous layer of (carbon) soot
Implementation Method 2
forming a continuous layer of carbon soot on mold assembly surfaces via thermal decomposition of hydrocarbons
Data Source
AI summary
A system for forming a glass article includes a mold assembly and a burner assembly. The mold assembly includes a mold body that defines an open cavity configured to receive a glass-containing material in a molten state. The mold assembly further includes a plunger configured to be actuated towards the mold body and into the open cavity to press the glass-containing material into a closed volume defined by the mold body and the plunger. The mold assembly further includes (i) first surfaces that define the closed volume and (ii) one or more pairs of second surfaces that make sliding contact when the plunger is actuated. The burner assembly is configured to form a solid lubricant on active surfaces of the mold assembly. The active surfaces include all the first surfaces and at least one second surface of each of the one or more pairs of second surfaces.