VIG Evacuation Head Ceramic Heater Uniform Temperature Profile
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Solution Overview
Problem
Vacuum insulating glazing (VIG) unit production faces challenges in achieving a better contact seal between the evacuation head and glass pane, enhanced evacuation tube seal, and maintaining tempered glass integrity during the manufacturing process, with existing technologies experiencing issues with temperature distribution and hermetic contact due to large evacuation head diameters and tungsten coil heaters.
Innovation Solution
A method involving a ceramic heating element with a smaller evacuation head diameter, temperature sensors, and a controlled heating profile to ensure a hermetic contact and efficient sealing of the evacuation tube tip, using a displaceable ceramic heating element to maintain uniform temperature and prevent thermal stress on tempered glass, while employing a compact evacuation head design with fins for improved thermal conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large evacuation head diameter is used, then the hermetic contact area with the glass pane is improved, but the temperature distribution becomes non-uniform and thermal stress on tempered glass increases
Solution Approach 1:
The patent applies local quality by using a smaller evacuation head diameter (20-40mm) concentrated at the critical sealing location rather than a large uniform head. This concentrates the hermetic contact where needed while limiting the heated area to prevent thermal stress on the tempered glass panes.
Solution Approach 2:
The patent changes the temperature parameter by implementing a controlled heating profile that raises the oven temperature to 150-300°C for sealing while maintaining the evacuation head temperature controlled to prevent excessive thermal stress. The heating element is activated only when the temperature difference exceeds a threshold (e.g., 10°C).
2Power
If a tungsten coil heater is used, then heating capability is provided, but temperature distribution uniformity deteriorates and thermal stress increases
Solution Approach 1:
The patent extracts the heating element from the traditional tungsten coil design and replaces it with a ceramic heating element. This extraction allows for more uniform heat distribution across the evacuation head surface while maintaining adequate heating power for sealing operations.
Solution Approach 2:
The patent uses a ceramic heating element (such as silicon nitride or aluminum nitride) which combines good thermal conductivity with uniform heat distribution properties. The ceramic material provides both the necessary heating power and improved temperature uniformity compared to tungsten coils.
3Manufacturing precision
If the evacuation head is heated to high temperature for sealing, then the seal quality is improved, but the tempered glass may lose its temper and strength
Solution Approach 1:
The patent applies local quality by concentrating the heating action only at the evacuation head contact area with the glass pane, rather than heating the entire glass surface. This localized heating achieves adequate seal quality while keeping the rest of the tempered glass below the temper loss temperature (typically below 200-300°C).
Solution Approach 2:
The patent implements continuous temperature monitoring and control during the sealing process. The heating element is activated only when the temperature difference between the oven and evacuation head exceeds a threshold (e.g., 10°C), maintaining continuous adequate seal heating while preventing overall glass temperature from reaching temper loss levels.
4Object-affected harmful factors
If a smaller evacuation head is used, then thermal stress on tempered glass is reduced, but the hermetic contact seal quality deteriorates
Solution Approach 1:
The patent changes the temperature parameter by implementing controlled heating during the sealing process. The heating element raises the evacuation head and glass contact area temperature to 150-300°C, which improves the hermetic seal quality by enhancing material flow and bonding, while the limited heated area (due to smaller head diameter) prevents excessive thermal stress on the tempered glass.
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 enhances the production of VIG units by achieving a better seal, reducing thermal stress on tempered glass, and improving the longevity of the glass panes through precise temperature control and a more uniform heat distribution, leading to improved energy efficiency and reduced manufacturing costs.
Implementation Method 1
the evacuation head 8 adapted to have a substantially hermetic contact to the glass pane face 1a; arranging the VIG unit and evacuation head 8 in an oven, the oven configured for heating and cooling according to a predetermined profile of oven temperatures T1; heating and cooling the oven according to the predetermined profile of oven temperatures T1 and compensating for a difference in temperature between the predetermined profile of oven temperatures T1 and a temperature T2 under the evacuation head 8 by activating the heating element 9
Implementation Method 2
using a displaceable ceramic heating element to maintain uniform temperature and prevent thermal stress on tempered glass, while employing a compact evacuation head design with fins for improved thermal conduction
Implementation Method 3
employing a compact evacuation head design with fins for improved thermal conduction
Data Source
AI summary
A method of producing a vacuum insulated glazing (VIG) unit comprising providing substantially parallel glass panes, a plurality of pillars, and a peripheral seal between the glass panes; providing an evacuation hole in a first glass pane for evacuating a void to a reduced pressure; covering the evacuation hole with an evacuation head comprising a heating element, the evacuation head having substantially hermetic contact to the first glass pane; arranging the glass panes, the plurality of pillars, the peripheral seal, and the evacuation head in an oven; heating the oven according to a predetermined profile of oven temperatures T1 and compensating for a difference in temperature between the temperatures T1 and a temperature T2 under the evacuation head by activating the heating element to increase the temperature T2 to equal the temperature T1; evacuating the void through the evacuation head after completion of the heating; and sealing the evacuation hole.