Vacuum Mold Shuttle System for Glass Forming Precision
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Solution Overview
Problem
Existing glass sheet forming systems face challenges in accurately forming hot glass sheets with compound curvature, leading to optical distortions due to buckling and uneven curvature, particularly in multi-stage forming processes where thermal expansion and contraction of equipment can affect precision.
Innovation Solution
A vacuum mold shuttle system with a three-stage forming station, utilizing a first upper mold with straight line elements for initial forming, followed by gravity sagging on a lower mold, and final press forming with a second upper mold, all controlled by a gas lift jet array and vacuum sources to achieve precise curvature and reduce distortions, while allowing for thermal movement adjustments through guide elements on the shuttle frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a multi-stage forming process is used to form hot glass sheets with compound curvature, then the curvature precision is improved, but thermal expansion and contraction of equipment affect positioning precision
Solution Approach 1:
The patent employs a dynamic positioning system where the mold support frame includes guide elements that allow controlled movement relative to the shuttle frame. This dynamic arrangement compensates for thermal expansion and contraction by permitting the mold to shift position slightly in response to temperature changes, maintaining positioning precision throughout the multi-stage forming process
Solution Approach 2:
The system changes the physical state and parameters of the glass sheet through controlled heating and cooling cycles during the multi-stage forming process. By carefully managing temperature parameters at each stage, the system achieves precise compound curvature while accounting for thermal effects on equipment dimensions
2Device complexity
If vacuum sources are mounted directly on the shuttle frame, then the vacuum system is simplified, but thermal expansion affects vacuum alignment
Solution Approach 1:
The vacuum sources are mounted on the shuttle frame but connected to the mold through flexible vacuum conduits rather than rigid direct connections. This dynamic connection allows the vacuum system to accommodate thermal expansion and contraction of the shuttle frame while maintaining proper vacuum alignment with the mold openings
Solution Approach 2:
The patent uses flexible vacuum conduits or bellows-like structures to connect the vacuum sources on the shuttle frame to the mold. These flexible connections can expand and contract with temperature changes, maintaining vacuum integrity and alignment without requiring complex rigid positioning mechanisms
3Stability of the object's composition
If guide elements constrain the mold support frame completely, then positioning stability is improved, but thermal expansion is restricted causing stress
Solution Approach 1:
The guide elements are designed to provide constrained stability in the primary operating directions while allowing controlled movement in directions affected by thermal expansion. This dynamic constraint system maintains positioning stability during forming operations while accommodating thermal growth, preventing stress buildup in the mold support frame
4Manufacturing precision
If a three-stage forming process is used, then compound curvature precision is improved, but cycle time increases
Solution Approach 1:
The three-stage forming process is designed to operate continuously without interruption between stages. The shuttle system maintains vacuum hold on the glass sheet throughout all three stages, allowing sequential forming operations to proceed without releasing and re-grabbing the workpiece, thereby reducing cycle time while maintaining precision
Solution Approach 2:
The system performs preliminary heating and positioning actions before each forming stage to minimize the time required during actual forming. The glass sheet is pre-heated to the appropriate temperature and the molds are pre-positioned, allowing the three stages to proceed rapidly with minimal idle time between operations
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 system effectively reduces optical distortions and achieves precise compound curvature in glass sheets by controlling thermal expansion and contraction, enabling efficient and accurate formation of hot glass sheets with reduced cycle time through coordinated movement of molds and vacuum control.
Implementation Method 1
at least one vacuum source mounted on the shuttle frame near the end of the beam opposite the end including the mold support frame support surface
Implementation Method 2
selectively drawing a vacuum at the downwardly facing surface of the mold
Implementation Method 3
A gas lift jet array may be located below the plane of conveyance to supply upwardly directed lift jets for lifting the glass sheet upwardly from the roll conveyor to the first upper mold
Implementation Method 4
a conveyor from which the first upper mold receives the glass sheet, including a heated chamber
Implementation Method 5
allowing for thermal movement adjustments through guide elements on the shuttle frame
Data Source
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AI summary
A vacuum mold shuttle system in a glass sheet forming system includes a vacuum mold mounted on a support frame. A shuttle frame including a pair of generally parallel elongate beams for receiving and supporting the mold support frame thereon. A vacuum source is mounted on the shuttle frame near the end of the beams opposite to the end supporting the mold, a conduit and coupling port for releasably connecting the mold to the vacuum source. At least one guide element is mounted on the support surface of one of the beams for receiving and fixing the position of the mold support frame relative to the shuttle frame to align and prevent movement of the mold support frame with respect to the shuttle frame in any direction as the mold support frame is supported thereon.