Glass Sheet Bending Vacuum Control for Cloth Mark Prevention
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Solution Overview
Problem
Existing glass bending methods often result in image distortion (cloth marks) due to uneven suction timing across vacuum chambers, leading to prolonged suction pressure on certain areas of the glass sheet.
Innovation Solution
A method and apparatus where suction holes are grouped into at least two groups, with negative pressures lowered at different timings to maintain appropriate pressure ranges, ensuring even bending and preventing cloth marks. The apparatus includes a supporting frame, a mold with suction holes, and a vacuum control unit to manage pressures, allowing for controlled suction and release to prevent distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If suction timings are shifted across different vacuum chambers to enable gradual glass sheet formation, then the glass sheet can be formed progressively from specific portions, but the total suction time becomes excessively long causing through-the-glass image distortion (cloth marks)
Solution Approach 1:
The suction holes are divided into multiple groups (first group, second group, third group) that operate at different timings. This segmentation allows progressive formation of the glass sheet while controlling the duration of suction pressure applied to each region, preventing cloth marks by ensuring that previously suctioned regions are released before completing the formation of other regions
Solution Approach 2:
The vacuum chambers are prepared with predetermined suction timings before the bending process begins. The control unit is configured to activate and deactivate vacuum chambers in a specific sequence, ensuring that regions are suctioned and released in advance of other regions to prevent excessive pressure duration that causes distortion
2Productivity
If high negative pressure is applied to all vacuum chambers simultaneously for efficient glass sheet bending, then the bending process is completed quickly, but cloth marks occur due to prolonged suction pressure on already formed portions
Solution Approach 1:
The suction pressure is made dynamic rather than static. Different vacuum chambers are activated and deactivated at different timings during the bending process. The control unit dynamically adjusts which chambers are under negative pressure at any given moment, allowing the system to maintain high productivity while preventing cloth marks through timed pressure variation
Solution Approach 2:
The vacuum chambers operate in periodic cycles of activation and deactivation. Each chamber follows a timed sequence where it applies negative pressure for a specific duration corresponding to the formation of its region, then releases pressure before other chambers complete their suction. This periodic action enables efficient bending while preventing excessive pressure duration
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 effectively prevents cloth marks by managing suction pressures across the glass sheet, ensuring even bending and reducing the risk of image distortion, particularly in regions with black ceramic paste layers.
Implementation Method 1
a vacuum forming step for providing a negative pressure through a plurality of suction holes formed on the forming surface so that the shape of the pressed glass sheet is bent along the forming surface of the mold
Implementation Method 2
a heating step for heating the glass sheet to soften the glass sheet
Data Source
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AI summary
It is an object of the present invention to provide a method for bending a glass sheet which can appropriately prevent cloth mark due to suctioning. The present invention is characterized by a method for bending a glass sheet comprising a heating step for heating a glass sheet to soften the glass sheet, and a bending step for bending the heated and softened glass sheet to have a predetermined shape, wherein the bending step comprises a step of pressing the heated and softened glass sheet, whose edges are supported by a supporting frame, against a forming surface of a bending mold opposed to the supporting frame, and a vacuum forming step for providing a negative pressure through a plurality of suction holes formed on the forming surface so that the shape of the pressed glass sheet is bent along the forming surface of the mold, and wherein in the vacuum forming step, the plurality of suction holes are grouped into at least two groups, and the raised negative pressures for the respective groups are lowered at different timings.